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How Does Light Travel?

Ever since Democritus – a Greek philosopher who lived between the 5th and 4th century’s BCE – argued that all of existence was made up of tiny indivisible atoms, scientists have been speculating as to the true nature of light. Whereas scientists ventured back and forth between the notion that light was a particle or a wave until the modern era, the 20th century led to breakthroughs that showed us that it behaves as both.

These included the discovery of the electron, the development of quantum theory, and Einstein’s Theory of Relativity . However, there remains many unanswered questions about light, many of which arise from its dual nature. For instance, how is it that light can be apparently without mass, but still behave as a particle? And how can it behave like a wave and pass through a vacuum, when all other waves require a medium to propagate?

Theory of Light to the 19th Century:

During the Scientific Revolution, scientists began moving away from Aristotelian scientific theories that had been seen as accepted canon for centuries. This included rejecting Aristotle’s theory of light, which viewed it as being a disturbance in the air (one of his four “elements” that composed matter), and embracing the more mechanistic view that light was composed of indivisible atoms.

In many ways, this theory had been previewed by atomists of Classical Antiquity – such as Democritus and Lucretius – both of whom viewed light as a unit of matter given off by the sun. By the 17th century, several scientists emerged who accepted this view, stating that light was made up of discrete particles (or “corpuscles”). This included Pierre Gassendi, a contemporary of René Descartes, Thomas Hobbes, Robert Boyle, and most famously, Sir Isaac Newton .

Newton’s corpuscular theory was an elaboration of his view of reality as an interaction of material points through forces. This theory would remain the accepted scientific view for more than 100 years, the principles of which were explained in his 1704 treatise “ Opticks, or, a Treatise of the Reflections, Refractions, Inflections, and Colours of Light “. According to Newton, the principles of light could be summed as follows:

• Every source of light emits large numbers of tiny particles known as corpuscles in a medium surrounding the source.
• These corpuscles are perfectly elastic, rigid, and weightless.

This represented a challenge to “wave theory”, which had been advocated by 17th century Dutch astronomer Christiaan Huygens . . These theories were first communicated in 1678 to the Paris Academy of Sciences and were published in 1690 in his “ Traité de la lumière “ (“ Treatise on Light “). In it, he argued a revised version of Descartes views, in which the speed of light is infinite and propagated by means of spherical waves emitted along the wave front.

Double-Slit Experiment:

By the early 19th century, scientists began to break with corpuscular theory. This was due in part to the fact that corpuscular theory failed to adequately explain the diffraction, interference and polarization of light, but was also because of various experiments that seemed to confirm the still-competing view that light behaved as a wave.

The most famous of these was arguably the Double-Slit Experiment , which was originally conducted by English polymath Thomas Young in 1801 (though Sir Isaac Newton is believed to have conducted something similar in his own time). In Young’s version of the experiment, he used a slip of paper with slits cut into it, and then pointed a light source at them to measure how light passed through it.

According to classical (i.e. Newtonian) particle theory, the results of the experiment should have corresponded to the slits, the impacts on the screen appearing in two vertical lines. Instead, the results showed that the coherent beams of light were interfering, creating a pattern of bright and dark bands on the screen. This contradicted classical particle theory, in which particles do not interfere with each other, but merely collide.

The only possible explanation for this pattern of interference was that the light beams were in fact behaving as waves. Thus, this experiment dispelled the notion that light consisted of corpuscles and played a vital part in the acceptance of the wave theory of light. However subsequent research, involving the discovery of the electron and electromagnetic radiation, would lead to scientists considering yet again that light behaved as a particle too, thus giving rise to wave-particle duality theory.

Electromagnetism and Special Relativity:

Prior to the 19th and 20th centuries, the speed of light had already been determined. The first recorded measurements were performed by Danish astronomer Ole Rømer, who demonstrated in 1676 using light measurements from Jupiter’s moon Io to show that light travels at a finite speed (rather than instantaneously).

By the late 19th century, James Clerk Maxwell proposed that light was an electromagnetic wave, and devised several equations (known as Maxwell’s equations ) to describe how electric and magnetic fields are generated and altered by each other and by charges and currents. By conducting measurements of different types of radiation (magnetic fields, ultraviolet and infrared radiation), he was able to calculate the speed of light in a vacuum (represented as c ).

In 1905, Albert Einstein published “ On the Electrodynamics of Moving Bodies ”, in which he advanced one of his most famous theories and overturned centuries of accepted notions and orthodoxies. In his paper, he postulated that the speed of light was the same in all inertial reference frames, regardless of the motion of the light source or the position of the observer.

Exploring the consequences of this theory is what led him to propose his theory of Special Relativity , which reconciled Maxwell’s equations for electricity and magnetism with the laws of mechanics, simplified the mathematical calculations, and accorded with the directly observed speed of light and accounted for the observed aberrations. It also demonstrated that the speed of light had relevance outside the context of light and electromagnetism.

For one, it introduced the idea that major changes occur when things move close the speed of light, including the time-space frame of a moving body appearing to slow down and contract in the direction of motion when measured in the frame of the observer. After centuries of increasingly precise measurements, the speed of light was determined to be 299,792,458 m/s in 1975.

Einstein and the Photon:

In 1905, Einstein also helped to resolve a great deal of confusion surrounding the behavior of electromagnetic radiation when he proposed that electrons are emitted from atoms when they absorb energy from light. Known as the photoelectric effect , Einstein based his idea on Planck’s earlier work with “black bodies” – materials that absorb electromagnetic energy instead of reflecting it (i.e. white bodies).

At the time, Einstein’s photoelectric effect was attempt to explain the “black body problem”, in which a black body emits electromagnetic radiation due to the object’s heat. This was a persistent problem in the world of physics, arising from the discovery of the electron, which had only happened eight years previous (thanks to British physicists led by J.J. Thompson and experiments using cathode ray tubes ).

At the time, scientists still believed that electromagnetic energy behaved as a wave, and were therefore hoping to be able to explain it in terms of classical physics. Einstein’s explanation represented a break with this, asserting that electromagnetic radiation behaved in ways that were consistent with a particle – a quantized form of light which he named “photons”. For this discovery, Einstein was awarded the Nobel Prize in 1921.

Wave-Particle Duality:

Subsequent theories on the behavior of light would further refine this idea, which included French physicist Louis-Victor de Broglie calculating the wavelength at which light functioned. This was followed by Heisenberg’s “uncertainty principle” (which stated that measuring the position of a photon accurately would disturb measurements of it momentum and vice versa), and Schrödinger’s paradox that claimed that all particles have a “wave function”.

In accordance with quantum mechanical explanation, Schrodinger proposed that all the information about a particle (in this case, a photon) is encoded in its wave function , a complex-valued function roughly analogous to the amplitude of a wave at each point in space. At some location, the measurement of the wave function will randomly “collapse”, or rather “decohere”, to a sharply peaked function. This was illustrated in Schrödinger famous paradox involving a closed box, a cat, and a vial of poison (known as the “ Schrödinger Cat” paradox).

According to his theory, wave function also evolves according to a differential equation (aka. the Schrödinger equation ). For particles with mass, this equation has solutions; but for particles with no mass, no solution existed. Further experiments involving the Double-Slit Experiment confirmed the dual nature of photons. where measuring devices were incorporated to observe the photons as they passed through the slits.

When this was done, the photons appeared in the form of particles and their impacts on the screen corresponded to the slits – tiny particle-sized spots distributed in straight vertical lines. By placing an observation device in place, the wave function of the photons collapsed and the light behaved as classical particles once more. As predicted by Schrödinger, this could only be resolved by claiming that light has a wave function, and that observing it causes the range of behavioral possibilities to collapse to the point where its behavior becomes predictable.

The development of Quantum Field Theory (QFT) was devised in the following decades to resolve much of the ambiguity around wave-particle duality. And in time, this theory was shown to apply to other particles and fundamental forces of interaction (such as weak and strong nuclear forces). Today, photons are part of the Standard Model of particle physics, where they are classified as boson – a class of subatomic particles that are force carriers and have no mass.

So how does light travel? Basically, traveling at incredible speeds (299 792 458 m/s) and at different wavelengths, depending on its energy. It also behaves as both a wave and a particle, able to propagate through mediums (like air and water) as well as space. It has no mass, but can still be absorbed, reflected, or refracted if it comes in contact with a medium. And in the end, the only thing that can truly divert it, or arrest it, is gravity (i.e. a black hole).

What we have learned about light and electromagnetism has been intrinsic to the revolution which took place in physics in the early 20th century, a revolution that we have been grappling with ever since. Thanks to the efforts of scientists like Maxwell, Planck, Einstein, Heisenberg and Schrodinger, we have learned much, but still have much to learn.

For instance, its interaction with gravity (along with weak and strong nuclear forces) remains a mystery. Unlocking this, and thus discovering a Theory of Everything (ToE) is something astronomers and physicists look forward to. Someday, we just might have it all figured out!

We have written many articles about light here at Universe Today. For example, here’s How Fast is the Speed of Light? , How Far is a Light Year? , What is Einstein’s Theory of Relativity?

If you’d like more info on light, check out these articles from The Physics Hypertextbook and NASA’s Mission Science page.

We’ve also recorded an entire episode of Astronomy Cast all about Interstellar Travel. Listen here, Episode 145: Interstellar Travel .

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56 Replies to “How Does Light Travel?”

“HOW DOES LIGHT TRAVEL?”

it travels lightly. 😀

Light doesn’t exist. This is an observation from light’s point of view and not ours. Traveling at the speed of (wait for it) light, absolutely no time passes between leaving it’s source and reaching it’s destination for the photon. This means, to the photon hitting your retina, it is also still on that star you are observing 10 light years away. How is this possible? Maybe John Wheeler was right when he told Richard Feynman that there is only one electron in the universe and it travels forward in time as an electron, then back in time as a positron and every electron we see is the same electron.

MY QUESTION IS: Whether light is a wave , particle or both.. where does it get the energy to move through space/time. In other words is the energy of light infinite? Does it continue on without lose of energy…..forever…….

I believe that Special Relativity says that the energy of light is infinite due to the very fact it has no mass. E=MC^2

In reverse, this is also why something with mass to begin with. If accelerated toward the speed of light, will see their mass and gravity increase to infinite points as they near relativistic speed (it actually starts around 95% with a steep upward curve from there), with a relative slowing to a stop of time.

Join the discussion

Light and the universe are only illusions that are formed in our minds via technology that sends information from the simulation program we’re living in. That information comes in the form of invisible wavelengths that includes wavelengths that we perceive as light. The visible retinas in our eyes are like tiny video screens where these particles are arranged into patterns that form into all the various objects we think are real objects. This information is also converted into thoughts within our minds which are like computer processors that process that information.

We are living in a computer simulation that is much more advanced than anything the characters in the program have built according to the information called the Beast.

Brad,…So You’re suggesting that “life” as we know and call it “is some kind of retro-virus” or “bio-intelligent format” heaped upon a perceived “set of accepted data sets” that are not in sync with each other in most cases with exception to Math 94% of the time….Even then it can vary which suggests Your idea would mean we all live in a fairy tale. That is what you suggest,…right?……

Brad has watched the Matrix too many times.

Correction: Even gravity doesn’t slow light down. Light (EM radiation of any wavelength) always travels at speed c, relative to any local inertial (Lorentz) frame. It could also be noted that the wavelength of an EM wave is not a characteristic of that wave alone; it also depends on the state of motion of the observer. You might even say, “One man’s radio wave is another man’s gamma ray.”

Light actually “slows down” every time it has to travel through anything but a vacuum. Look up Cherenkov radiation to see what happens when light initially travels faster than it can through a particular substance, like water. Light speed is not constant when traveling through any medium except pure vacuum. In fact that is why your pencil looks bent when you drop it in a glass of water. Light bends to find it’s fastest path through any medium, and it slows down in that medium.

if all you scientist could ever get it in your pie brain that there is no time, no light speed, no warping space, no black holes for the purpose of moving through space quickly, no smallest no biggest when it comes to space and that all of everything has always been in existence but not necessarily as it is now. you will never find the smallest because if it exist it has an inside, and you will never find the end of space because it is infinite.

What are you smoking?

The article started out nicely, but I lost interest as mistakes began to appear. First Einstein did not “propose” the photoelectric effect. The photoelectric effect was first observed by Heinrich Hertz in 1887. Einstein used the idea of photons to explain the photoelectric effect and derive the photoelectric equation. Also, Max Plank had already derived the blackbody distribution, by assuming that electromagnetic energy of frequency f could only be emitted in multiples of energy E=hf, by 1900. Einstein’s paper on the photoelectric effect was published in his “miracle” year of 1905. The photoelectric effect has nothing to do with black body radiation.

Einstein did not coin the name “photons” for light quanta, as stated in this article. This term was first used by Arthur Compton in 1928.

I have to say that I do not know what the author of the article means when he says ” calculating the wavelength at which light functioned” in reference to Louis-Victor de Broglie. Louis de Broglie used the dual nature of light to suggest that electrons, previously thought of as particles, also had wave characteristics and used this notion to explain the Bohr orbits in the hydrogen atom.

I gave up on the article after seeing these errors. I’m afraid I have a low tolerance for sloppy writing.

Oh, it’s BCE now, “Before the Common Era” BC has worked for 2000 years but now the PC police have stepped in so as not to offend who? Some Muslims?

mecheng1, you must be very young. BCE has been in used in academia for decades. It’s nothing “new”, just out of your circle of knowledge.

Decades??? Really?? How does that compare to 2000 years?

Only in Euro-centric texts have your assertions been true, McCowen. The rest of the world not influenced by Christianity have used their own calendars and a “0” year or a “year 1” from which to reckon the passage of time, largely based on their own religions or celestial observations.

Over the last century or so, through commerce, most of the world has generally accepted the use of a Western calendar (or use it along with their own for domestic purposes, like we here in the US still use Imperial units of measure that have to be converted to metric for international commerce). So, we are in a “common era” insofar as non-Christian societies are incorporating the Gregorian Calendar and the generally-accepted “year 1” established by that calendar (which is supposed to be the year of Jesus’s birth, but it probably isn’t according to current scholarship). Besides, the Gregorian calendar is an improved derivative of the Roman calendar – even the names of the months come from the Romans.

In short, it is more accurate, as well as respectful, to go with BCE in these global times.

Where is the information carried on a photon hitting my eye(s), or cluster/group/pack of photons hitting my eyes(s), that I see as other distant galaxies and planets going around stars?

That’s the mystery, isn’t it? Even in scattering, light remains coherent enough to convey an enormous amount of information.

Since the miniscule equal masses with opposite charges, that make up the photon structure, interact at 90 degrees, this induces a spin (a finding from the 80’s by the LANL plasma physics program) which creates a centrifugal force that counterbalances the charge attraction of the opposite charges. This establishes a stable structure for energies less than 1.0216 MeV, the pair-formation threshold, separating these “neutrino” sub-components by a specific distance providing wavelengths varying with photon energy. This composite photon propagates transversely at c/n, the speed of light divided by the index of refraction of the material traversed. In spite of the mass being defined as zero, for convenience in calculating atomic masses, there is actually an infinitesimal but non-zero mass for the photon that is required for calculations that describe its properties.

Tim, you poor guy! You have a discombobulated brain! Everything you wrote is just gibberish.

i would like to know the temperature in a black hole…maybe absolute zero? is absolute zero the moment that time stop?

I think the temp inside a black hole would be extremely high since temperature seems to increase with mass. Comparing absolute zero to time stopping is very interesting though. To the observer they would appear the same.

Theoretically there is no temperature in a black hole from any observer POV because time is stopped. Although JALNIN does bring up that point, and he also brings up the point of increasing mass corresponding to increasing energy. Everything in Hawking and Einstein’s equations though, suggest that any energy would be absorbed back by the singularity, so there wouldn’t be any heat. In fact it should be infinitely cold. But time is no more, so technically no heat or energy is emitted anyway from any observers POV. Yet recent images of black holes from Chandra show that they emit powerful Gamma Jets along their spin axis just like Neutron stars, and Pulsars. BTW edison. The accretion disk can reach temperatures of 20MN Kelvin on a feeding SM black hole (quasar). NASA just published an article on it through the Chandra feed a while back.

Light doesn’t travel, it just IS. It is we, the condensed matter, that travels, through time.

Oh really? Is this just your imagination/illusion or you have published a paper on it?

So you don’t believe you travel through time?

I wish I understood just a portion of I just read, love sicence so bad BUT, sighs

It would be easier to understand if it wasn’t pure gibberish written by someone with no science background.

I have two “mind-bending relativity side effects” to share. At least they are mind-bending to me.

1) Light travels the same speed relative to all particles of mass, regardless of how those particles move relative to each other:

I can conceptualize this if we are only talking about two mass-particles/observers and the examples I’ve seen always involve only two observers. But if you have many mass-particles/observers, how does the space-time seem to know to adjust differently for all of them. I am sure i am understanding this correctly as it is a basic concept of special relativity and nobody seems to bring this issue up. But it “bends my mind” when i try to include more than two observers. Maybe you can help.

2) General Relativity’s (“GR”) prediction that the big bang started with “Infinite” energy and now the universe appears to have finite mass energy and Regarding the first effect: How can something infinite turn into something finite? Is the answer that at that early in the universe, quantum takes over and GR’s prediction of infinite mass-energy at the start of the universe is just wrong?

I need to correct a typo in my previous comment. Where i say “i am sure am understanding this correctly” I meant to include the word NOT. so it should read “i am sure am NOT understanding this correctly” Mark L.

Mark,….I think you’re understanding it just fine from the standpoint of multiple observers, The point might be that in space, the density of “emptiness” or “lack of emptiness” might be impacted from one area of observation to another by an observer who’s perceptions are not equal but not being taken into consideration by each observer. ( an example if I may?) If you were to use a Clear medium which is oil based beginning with 5 gallons of mineral spirits in a large barrel and keep adding 5 gallons of thicker clear oil and then heavy grease and stop with using a clear heavy wax,…what happens is you end up with a barrel of clear fluid that begins with a floating substrate but the liquid begins to keep floating and the heaviest stuff goes to the bottom,…You end up with a sort of solid tube of clear fluids which if you could keep them in shape here on the earth, “you could observe them” from several positions, #1. the fluid end #2, the less fluid part, #3, the semi solid part #4. the seemingly solid part #5. the almost solid part & #6. the solid part……all of which would be transparent….You could then shine a laser through all of it and perhaps do that again from different places and see what happens at different angles…..I think what happens as a result would be, an observer would end up be influenced as per his or her ideas thusly because of the quasi-nature of what the density of space is at the point of space is where the observation is made. just a guess.

All Special Relativity really says about light is that it appears to move at the same rate from any observer POV. There are other more advanced rules relating to light speeds. One of them is the implication of infinite energy in a photon because of the fact it’s mass-less, therefore it can move at the maximum rate a mass-less particle or wave can (not necessarily that it does) Later when the electron was discovered (also mass-less particle or wave), it was also found to conform to the rules of special relativity.

As far as the big bang, there are a lot of cracks in that theory, and many different ones are beginning to dispute some of the common ideas behind the “Big Bang” as well as “Inflationary Cosmology”. Honestly though, both standard and quantum physics applied, and yet both went out the window at the same time at some point. That’s what all the theories really say. At some point, everything we know or think we know was bunk, because the math just breaks down, and doesn’t work right anymore.

i think until there is an understanding of the actual “fabric” of space itself, the wave vs particle confusion will continue. another interesting article recently was the half integer values of rotating light. planck’s constant was broken? gravity? a bump in the data? lol these are interesting times.

There’s no fabric.

Tesla insists there is an aether, Einstein says not. Tesla enjoyed far less trial and error than Einstein. The vast majority of Tesla’s projects worked the first time around and required no development or experimentation. I’ll go with Tesla; there is an aether as a fabric of space.

http://weinsteinsletter.weebly.com/aether.html

Maybe Special Relativity is not correct? 🙂

Feynman said unequivocally that QED is NOT a wave theory. In fact, the math only looks like Maxwell’s wave function when you are looking at a single particle at a time, but the analogy breaks down as soon as you start looking at the interactions of more than one, which is the real case. There’s no light acting alone, but always an interaction between a photon and some other particle, an electron, another photon, or whatever. He said “light is particles.” So the question re: how can light travel through a vacuum if it’s waves is a nonsensical question. There are no collapsing wave functions in light. There’s only probabilities of position that look like waves on a freaking piece of paper. Even calling light properties as “wavelengths” is nonsensical. Light comes in frequencies, i.e., the number of particles traveling tightly together. Higher frequency is more energy because it’s more particles (E=MC[squared]). “Wavicles” is pure bullshit.

I don’t agree with the John Wheeler theory that there is only one electron since the computer I am using was built by ion implantation and uses a very large number of them simultaneously to function.

Black holes don’t stop or slow light, if they even exist. A black hole could phase shift light, which is why we see things emitting xrays and call them black holes….but they could be something else too.

Photons have no mass but they do have energy. Energy and mass are transformable into each other. Gravity works on energy as well as mass. As massive particles approach the speed of light their measurable mass increases to infinity. But since energy is equivalent to mass, why doesn’t the photon, which has energy, not seem to have infinite mass?

NO other wave travels thru a vacuum? what about radio?

Radio waves are a specific frequency range of light.

Technically speaking, radio waves are emitted at various frequencies that share the same space time as light. They are not however light. They’re modulated electrons. Modulated photons certainly can be used to carry a vast amount of information a great distance. It cannot do it any faster or better than a radio wave though. Both electrons and photons are mass-less, therefore they both conform to the rules of Special Relativity in the same way. Both travel at the speed of light.

I just don’t understand is it a particle of a wave? It seems like it behaves like wave and sometimes like particle and in some situations is like a what ever you are going to call it.

So, the logical idea would to have formula Photon_influence * weight_for_particle + Wave_influence * weight_for_wave

Make it more compact.

This article is good but the title is bad as by the end we still weren’t told how light travels through space. Also, there are some historical mistakes as already pointed out. Now for my contribution: I think that light and Gravity have a lot in common; for one – an atom’s electrons transmit light and an atom contains the tiny heavy place that knows everything there is to know about gravity, that is, the nucleus. Light and Gravity are both related to the same entity, the atom. Unfortunately, we, still cannot grasp how what’s heavy brings about gravitation. For those of you with a creed for new ideas go to: https://www.academia.edu/10785615/Gravity_is_emergent It’s a hypothesis…

Gravity and light are infinite, like space and time… Mind the concept that there are waves within waves, motions within motion, vibrations within vibration, endless overtones and universal harmony…

From this article, I have “And in the end, the only thing that can truly slow down or arrest the speed of light is gravity”

Doesn’t light slow down in water and glass and other mediums. I was only a Physics minor, but I do remember coivering this though way back in the early 80’s. And in my quick checking online, I found the following.

“Light travels at approximately 300,000 kilometers per second in a vacuum, which has a refractive index of 1.0, but it slows down to 225,000 kilometers per second in water (refractive index = 1.3; see Figure 1) and 200,000 kilometers per second in glass (refractive index of 1.5).”

Were they saying something else here. I did like the article.

Photons are not massless, but their mass is incredibly small even compared to a proton or neutron. So, by Einstein’s E=MC^2, the energy required for a photon to move is greatly reduced, but photons do have mass and are affected by gravity. If photons had no mass at all, then gravity would have no affect on them, but gravity does. Gravity bends light and can change it’s course through space. We see that in the actual test first performed to prove Einstein’s theory buy observing the distorted placement of stars as their light passes near the sun observed during an eclipse. We can also see it through gravitational lensing when viewing deeps space objects. And the fact that there are black holes that are black because light cannot escape it’s gravity. So photons do have mass, be it miniscule, and with that their propagation with light waves through space will eventually run out of energy and stop. but this would probably require distances greater to several widths of our universe to accomplish. Light from the furthest reaches of the universe are not as bright, or as energetic, as they are at anyplace between here and their origins. That reduction in their energy is also attributed to Einstein’s equation and the inverse square law, where the intensity of light is in relation to the inverse square of the distance. That proves that light looses energy the further it travels, but it still moves at the speed of light. As light looses energy, it doesn’t slow the light wave.

It has been proven that more energetic light does in fact travel slightly faster. You can find the experiments done with light that has traveled billions of light years, the more energetic is in fact faster over a number of seconds, around 10 -15 or so. As people encounter this information, they see that many accepted theories can now be debunked.

The point of the article is nothing new; light acts like a particle AND a beam. So when you sit behind a closed door and someone shines a light on the door, the light will engulf the door and wave through and around the edges, the particle does not just bounce straight back. You can focus a beam of light on an object, but it will sneak though the corners and underneath the door, through any opening,. And yes, light travels forever. It is a constant, that cannot be sped up. We can slow it down by focusing it through prisims or crystals. But it still is traveling at 186,000/MPS.and that speed does not change. So, that is why we can see the outer edge of the universe: 13,8B light years away *the time that it takes for light to travel in one year, is one light year. So, it has taken 13,8B light years for the light of other galaxies to get here, so those galaxies could be gone by now, since it took so long to reach us, We are truly looking back in time as we see the light emitted from those galaxies and stars.

It propagates through the quantum mish-mash know as the aether . . .

If light is a particle and particles have mass why does not the mas increase with it speed?

Wow…there are errors in the article, yes…the enthusiasm demonstrated by all the comments is encouraging…but when I read these comments, I am a bit dismayed at the lack of understanding that is evident in most of them…confusing energy and intensity and wavelength…confusing rest mass and inertial mass…not to mention some off-the-wall hypotheses with no experimental evidence to support them. There are some great primers out there…books, documentaries, podcasts (like Astronomy Cast). Good luck!

Precisely correct. Sci-fi rules basic physics, which reflects on the poor education system. Pity.

First time I heard about A. A. and his theory about light I really didn’t like him. Why? Because light was the the fastest thing in the universe and there is no other thing faster than the light. Later, when I have red about angular speed I have asked my self if you have linear and angular speed and both of them are speeds how that will result in the maximum speed. Since then, I have not had a chance to get right answer.

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How Does Light Travel Through Space? Facts & FAQ

Last Updated on Mar 15 2024

Light is such a fundamental part of our lives. From the moment we’re born, we are showered with all kinds of electromagnetic radiation, both colorful, and invisible. Light travels through the vacuum of space at 186,828 miles per second as transverse waves , outside of any material or medium, because photons—the particles that make up light—also behave as waves. This is referred to as the wave-particle duality of light.  

• What Is Light?

The wave-particle duality of light simply means that light behaves as both waves and particles . Although this has been long accepted as fact, scientists only managed to observe both these properties of light ¹ simultaneously for the first time in 2015.

As a wave, light is electromagnetic radiation—vibrations, or oscillations, of the electric and magnetic fields. As particles, light is made up of little massless packets of energy called photons ¹ .

• What Are Light Waves?

Waves are the transference of energy from one point to another. If we dropped a pebble into a small pond, the energy that the impact creates would transfer as a ripple, or a wave, that travels through the surface of the water, from one water particle to another, until eventually reaching the edge of the pond.

This is also how sound waves work—except that, with sound, it’s the pressure or vibrations of particles in the air that eventually reach our ears.

Unlike water and sound, light itself is electromagnetic radiation—or light waves—so it doesn’t need a medium to travel through.

• What Are Transverse Waves?

Light propagates through transverse waves. Transverse waves refer to a way in which energy is transferred.

Transverse waves oscillate at a 90-degree angle (or right angle) to the direction the energy is traveling in. An easy way to picture this is to imagine an S shape flipped onto its side. The waves would be going up and down, while the energy would be moving either left or right.

With light waves ¹ , there are 2 oscillations to consider. If the light wave is traveling on the X axis, then the oscillations of the electric field would be at a right angle, either along the Y or Z axes, and the oscillations of the magnetic field would be on the other.

• Can Anything Travel Faster Than Light?

The simple answer to this question is no, as far as we know at this time, nothing can go faster than the speed of light ¹ . Albert Einstein’s special theory of relativity states that “no known object can travel faster than the speed of light in a vacuum.”

Space and time don’t yet exist beyond the speed of light—if we were to travel that fast, the closer we get to the speed of light, the more our spatial dimension would shrink, until eventually collapsing.

Beyond this, the laws of physics state that as an object approaches the speed of light , its mass would become infinite, and so would the energy it would need to propel it. Since it’s probably impossible to create an infinite amount of energy, it would be difficult for anything to travel faster than light.

Tachyon, a hypothetical particle, is said to travel faster than the speed of light. However, because its speed would not be consistent with the known laws of physics, physicists believe that tachyon particles do not exist.

• Final Thoughts

Light travels through space as transverse, electromagnetic waves. Its wave-particle duality means that it behaves as both particles and waves. As far as we know, nothing in the world travels as fast as light.

• https://phys.org/news/2015-03-particle.html
• https://www.nature.com/articles/ncomms7407
• https://www.wtamu.edu/~cbaird/sq/2017/07/20/is-the-reason-that-nothing-can-go-faster-than-light-because-we-have-not-tried-hard-enough/
• https://www.physics.brocku.ca/PPLATO/h-flap/phys6_1f_1.png
• https://science.nasa.gov/ems/02_anatomy

Featured Image Credit: NASA, Unsplash

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About the Author Cheryl Regan

Cheryl is a freelance content and copywriter from the United Kingdom. Her interests include hiking and amateur astronomy but focuses her writing on gardening and photography. If she isn't writing she can be found curled up with a coffee and her pet cat.

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What is the speed of light?

Light is faster than anything else in the known universe, though its speed can change depending on what it's passing through.

The universe has a speed limit, and it's the speed of light. Nothing can travel faster than light — not even our best spacecraft — according to the laws of physics.

So, what is the speed of light? 

Light moves at an incredible 186,000 miles per second (300,000 kilometers per second), equivalent to almost 700 million mph (more than 1 billion km/h). That's fast enough to circumnavigate the globe 7.5 times in one second, while a typical passenger jet would take more than two days to go around once (and that doesn't include stops for fuel or layovers!). 

Light moves so fast that, for much of human history, we thought it traveled instantaneously. As early as the late 1600s, though, scientist Ole Roemer was able to measure the speed of light (usually referred to as c ) by using observations of Jupiter's moons, according to Britannica . 

Around the turn of the 19th century, physicist James Clerk Maxwell created his theories of electromagnetism . Light is itself made up of electric and magnetic fields, so electromagnetism could describe the behavior and motion of light — including its theoretical speed. That value was 299,788 kilometers per second, with a margin of error of plus or minus 30. In the 1970s, physicists used lasers to measure the speed of light with much greater precision, leaving an error of only 0.001. Nowadays, the speed of light is used to define units of length, so its value is fixed; humans have essentially agreed the speed of light is 299,792.458 kilometers per second, exactly.

Light doesn't always have to go so fast, though. Depending on what it's traveling through — air, water, diamonds, etc. — it can slow down. The official speed of light is measured as if it's traveling in a vacuum, a space with no air or anything to get in the way. You can most clearly see differences in the speed of light in something like a prism, where certain energies of light bend more than others, creating a rainbow.

— How many moons does Earth have ?

— What would happen if the moon were twice as close to Earth?

— If you're on the moon, does the Earth appear to go through phases?

Interestingly, the speed of light is no match for the vast distances of space, which is itself a vacuum. It takes 8 minutes for light from the sun to reach Earth, and a couple years for light from the other closest stars (like Proxima Centauri) to get to our planet. This is why astronomers use the unit light-years — the distance light can travel in one year — to measure vast distances in space.

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Because of this universal speed limit, telescopes are essentially time machines . When astronomers look at a star 500 light-years away, they're looking at light from 500 years ago. Light from around 13 billion light-years away (equivalently, 13 billion years ago) shows up as the cosmic microwave background, remnant radiation from the Big Bang in the universe's infancy. The speed of light isn't just a quirk of physics; it has enabled modern astronomy as we know it, and it shapes the way we see the world — literally.

Briley Lewis (she/her) is a freelance science writer and Ph.D. Candidate/NSF Fellow at the University of California, Los Angeles studying Astronomy & Astrophysics. Follow her on Twitter  @briles_34 or visit her website  www.briley-lewis.com .

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How to travel at (nearly) the speed of light.

One hundred years ago, on May 29, 1919, measurements of a solar eclipse offered proof for Einstein’s theory of general relativity. Even before that, Einstein had developed the theory of special relativity, which revolutionized the way we understand light. To this day, it provides guidance on understanding how particles move through space — a key area of research to keep spacecraft and astronauts safe from radiation.

The theory of special relativity showed that particles of light, photons, travel through a vacuum at a constant pace of 670,616,629 miles per hour — a speed that’s immensely difficult to achieve and impossible to surpass in that environment. Yet all across space, from black holes to our near-Earth environment, particles are, in fact, being accelerated to incredible speeds, some even reaching 99.9% the speed of light.

Scientists suspect magnetic reconnection is one way that particles are accelerated to nearly light speed. This illustration depicts the magnetic fields around Earth, which snap and realign, causing charged particles to be flung away at high speeds. Find out all three ways that this acceleration happens .

Image Credit: NASA

What Is a Light-Year?

An image of distant galaxies captured by the NASA/ESA Hubble Space Telescope. Credit: ESA/Hubble & NASA, RELICS; Acknowledgment: D. Coe et al.

For most space objects, we use light-years to describe their distance. A light-year is the distance light travels in one Earth year. One light-year is about 6 trillion miles (9 trillion km). That is a 6 with 12 zeros behind it!

Looking Back in Time

When we use powerful telescopes to look at distant objects in space, we are actually looking back in time. How can this be?

Light travels at a speed of 186,000 miles (or 300,000 km) per second. This seems really fast, but objects in space are so far away that it takes a lot of time for their light to reach us. The farther an object is, the farther in the past we see it.

Our Sun is the closest star to us. It is about 93 million miles away. So, the Sun's light takes about 8.3 minutes to reach us. This means that we always see the Sun as it was about 8.3 minutes ago.

The next closest star to us is about 4.3 light-years away. So, when we see this star today, we’re actually seeing it as it was 4.3 years ago. All of the other stars we can see with our eyes are farther, some even thousands of light-years away.

Stars are found in large groups called galaxies . A galaxy can have millions or billions of stars. The nearest large galaxy to us, Andromeda, is 2.5 million light-years away. So, we see Andromeda as it was 2.5 million years in the past. The universe is filled with billions of galaxies, all farther away than this. Some of these galaxies are much farther away.

An image of the Andromeda galaxy, as seen by NASA's GALEX observatory. Credit: NASA/JPL-Caltech

In 2016, NASA's Hubble Space Telescope looked at the farthest galaxy ever seen, called GN-z11. It is 13.4 billion light-years away, so today we can see it as it was 13.4 billion years ago. That is only 400 million years after the big bang . It is one of the first galaxies ever formed in the universe.

Learning about the very first galaxies that formed after the big bang, like this one, helps us understand what the early universe was like.

This picture shows hundreds of very old and distant galaxies. The oldest one found so far in GN-z11 (shown in the close up image). The image is a bit blurry because this galaxy is so far away. Credit: NASA, ESA, P. Oesch (Yale University), G. Brammer (STScI), P. van Dokkum (Yale University), and G. Illingworth (University of California, Santa Cruz)

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Warp drives: Physicists give chances of faster-than -light space travel a boost

Associate Professor of Physics, Oklahoma State University

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The closest star to Earth is Proxima Centauri. It is about 4.25 light-years away, or about 25 trillion miles (40 trillion km). The fastest ever spacecraft, the now- in-space Parker Solar Probe will reach a top speed of 450,000 mph. It would take just 20 seconds to go from Los Angeles to New York City at that speed, but it would take the solar probe about 6,633 years to reach Earth’s nearest neighboring solar system.

If humanity ever wants to travel easily between stars, people will need to go faster than light. But so far, faster-than-light travel is possible only in science fiction.

In Issac Asimov’s Foundation series , humanity can travel from planet to planet, star to star or across the universe using jump drives. As a kid, I read as many of those stories as I could get my hands on. I am now a theoretical physicist and study nanotechnology, but I am still fascinated by the ways humanity could one day travel in space.

Some characters – like the astronauts in the movies “Interstellar” and “Thor” – use wormholes to travel between solar systems in seconds. Another approach – familiar to “Star Trek” fans – is warp drive technology. Warp drives are theoretically possible if still far-fetched technology. Two recent papers made headlines in March when researchers claimed to have overcome one of the many challenges that stand between the theory of warp drives and reality.

But how do these theoretical warp drives really work? And will humans be making the jump to warp speed anytime soon?

Compression and expansion

Physicists’ current understanding of spacetime comes from Albert Einstein’s theory of General Relativity . General Relativity states that space and time are fused and that nothing can travel faster than the speed of light. General relativity also describes how mass and energy warp spacetime – hefty objects like stars and black holes curve spacetime around them. This curvature is what you feel as gravity and why many spacefaring heroes worry about “getting stuck in” or “falling into” a gravity well. Early science fiction writers John Campbell and Asimov saw this warping as a way to skirt the speed limit.

What if a starship could compress space in front of it while expanding spacetime behind it? “Star Trek” took this idea and named it the warp drive.

In 1994, Miguel Alcubierre, a Mexican theoretical physicist, showed that compressing spacetime in front of the spaceship while expanding it behind was mathematically possible within the laws of General Relativity . So, what does that mean? Imagine the distance between two points is 10 meters (33 feet). If you are standing at point A and can travel one meter per second, it would take 10 seconds to get to point B. However, let’s say you could somehow compress the space between you and point B so that the interval is now just one meter. Then, moving through spacetime at your maximum speed of one meter per second, you would be able to reach point B in about one second. In theory, this approach does not contradict the laws of relativity since you are not moving faster than light in the space around you. Alcubierre showed that the warp drive from “Star Trek” was in fact theoretically possible.

Proxima Centauri here we come, right? Unfortunately, Alcubierre’s method of compressing spacetime had one problem: it requires negative energy or negative mass.

A negative energy problem

Alcubierre’s warp drive would work by creating a bubble of flat spacetime around the spaceship and curving spacetime around that bubble to reduce distances. The warp drive would require either negative mass – a theorized type of matter – or a ring of negative energy density to work. Physicists have never observed negative mass, so that leaves negative energy as the only option.

To create negative energy, a warp drive would use a huge amount of mass to create an imbalance between particles and antiparticles. For example, if an electron and an antielectron appear near the warp drive, one of the particles would get trapped by the mass and this results in an imbalance. This imbalance results in negative energy density. Alcubierre’s warp drive would use this negative energy to create the spacetime bubble.

But for a warp drive to generate enough negative energy, you would need a lot of matter. Alcubierre estimated that a warp drive with a 100-meter bubble would require the mass of the entire visible universe .

In 1999, physicist Chris Van Den Broeck showed that expanding the volume inside the bubble but keeping the surface area constant would reduce the energy requirements significantly , to just about the mass of the sun. A significant improvement, but still far beyond all practical possibilities.

A sci-fi future?

Two recent papers – one by Alexey Bobrick and Gianni Martire and another by Erik Lentz – provide solutions that seem to bring warp drives closer to reality.

Bobrick and Martire realized that by modifying spacetime within the bubble in a certain way, they could remove the need to use negative energy. This solution, though, does not produce a warp drive that can go faster than light.

[ Over 100,000 readers rely on The Conversation’s newsletter to understand the world. Sign up today .]

Independently, Lentz also proposed a solution that does not require negative energy. He used a different geometric approach to solve the equations of General Relativity, and by doing so, he found that a warp drive wouldn’t need to use negative energy. Lentz’s solution would allow the bubble to travel faster than the speed of light.

It is essential to point out that these exciting developments are mathematical models. As a physicist, I won’t fully trust models until we have experimental proof. Yet, the science of warp drives is coming into view. As a science fiction fan, I welcome all this innovative thinking. In the words of Captain Picard , things are only impossible until they are not.

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Does Light Travel Forever?

Most recent answer: 01/23/2013

Hi Raja, Good question. First, let's think about why sound does not travel forever. Sound cannot travel through empty space; it is carried by vibrations in a material, or medium (like air, steel, water, wood, etc). As the particles in the medium vibrate, energy is lost to heat, viscous processes, and molecular motion. So, the sound wave gets smaller and smaller until it disappears. In contrast, light waves can travel through a vacuum, and do not require a medium. In empty space, the wave does not dissipate (grow smaller) no matter how far it travels, because the wave is not interacting with anything else. This is why light from distant stars can travel through space for billions of light-years and still reach us on earth. However, light can also travel within some materials, like glass and water. In this case, some light is absorbed and lost as heat, just like sound. So, underwater, or in our atmosphere, light will only travel some finite range (which is different depending on the properties of the material it travels through). There is one more aspect of wave travel to consider, which applies to both sound and light waves. As a wave travels from a source, it propagates outward in all directions. Therefore, it fills a space given approximately by the surface area of a sphere. This area increases by the square of the distance R from the source; since the wave fills up all this space, its intensity decreases by R squared. This effect just means that the light/sound source will appear dimmer if we are farther away from it, since we don't collect all the light it emits. For example, light from a distant star travels outward in a giant sphere. Only one tiny patch of this sphere of light actually hits our eyes, which is why stars don't blind us! David Schmid

(published on 01/23/2013)

Follow-Up #1: How far does light go?

Light just keeps going and going until it bumps into something.  Then it can either be reflected or absorbed.  Astronomers have detected some light that has been traveling for more that 12 billion years, close to the age of the universe.   

Light has some interesting properties.   It comes in lumps called photons.  These photons carry energy and momentum in specific amounts related to the color of the light.  There is much to learned about light.   I suggest you log in to our website and type  LIGHT into the search box.   Lots of interesting stuff there.

To answer your previous question "Can light go into a black hole?" ,  the answer is yes.

(published on 12/03/2015)

Follow-Up #2: less than one photon?

Certainly you can run the ouput of a single-photon source through a half-silvered mirror, and get a sort of half-ghost of the photon in two places. If you put ordinary photon detectors in those places, however, each will either detect zero or one. For each source photon, you'll get at most one of the detectors to find it. How does the half-ghost at the other one know whether it's detectably there or not? The name of that mystery is "quantum entanglement". At some level we don't really know the answer.

(published on 02/04/2016)

Follow-Up #3: stars too far away to see?

Most stars are too far for us to see them as individual stars even with our best telescopes. Still, we can get light from them, mixed with light from other stars. If our understanding of the universe is at all right, there are also stars that once were visible from here but now are outside our horizon so no light from them reaches us. It's probable that there are many more stars outside our horizon than inside, maybe infinitely more. It's hard to check, however, what's happening outside our horizon! It's even hard to define what we mean by "now" for things outside the horizon.

(published on 07/22/2016)

Follow-Up #4: light going out to space

Certainly ordinary light travels out to space. That's how spy cameras and such can take pictures of things here on the Earth's surface.

(published on 09/01/2016)

Follow-Up #5: end of the universe?

We don't think there's any "end" in the sense of some spatial boundary. Unless something changes drastically, there also won't be an end in time. The expansion looks like it will go on forever. So that wouldn't give a maximum range.

(published on 03/26/2017)

Follow-Up #6: seeing black holes

In principle a well-aimed beam would loop around the outside of the black hole and return to Earth. There aren't any black holes close enough to make this practical. Instead the bending of light by black holes is observed by their lensing effect on light coming from more distant objects.

The amazing gravitational wave signals observed from merging black holes provide even more direct and convincing proof that black holes exist and follow the laws of General Relativity.

(published on 01/29/2018)

Follow-up on this answer

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A Groundbreaking Scientific Discovery Just Gave Humanity the Keys to Interstellar Travel

In a first, this warp drive actually obeys the laws of physics.

If a superluminal—meaning faster than the speed of light—warp drive like Alcubierre’s worked, it would revolutionize humanity’s endeavors across the universe , allowing us, perhaps, to reach Alpha Centauri, our closest star system, in days or weeks even though it’s four light years away.

However, the Alcubierre drive has a glaring problem: the force behind its operation, called “negative energy,” involves exotic particles—hypothetical matter that, as far as we know, doesn’t exist in our universe. Described only in mathematical terms, exotic particles act in unexpected ways, like having negative mass and working in opposition to gravity (in fact, it has “anti-gravity”). For the past 30 years, scientists have been publishing research that chips away at the inherent hurdles to light speed revealed in Alcubierre’s foundational 1994 article published in the peer-reviewed journal Classical and Quantum Gravity .

Now, researchers at the New York City-based think tank Applied Physics believe they’ve found a creative new approach to solving the warp drive’s fundamental roadblock. Along with colleagues from other institutions, the team envisioned a “positive energy” system that doesn’t violate the known laws of physics . It’s a game-changer, say two of the study’s authors: Gianni Martire, CEO of Applied Physics, and Jared Fuchs, Ph.D., a senior scientist there. Their work, also published in Classical and Quantum Gravity in late April, could be the first chapter in the manual for interstellar spaceflight.

POSITIVE ENERGY MAKES all the difference. Imagine you are an astronaut in space, pushing a tennis ball away from you. Instead of moving away, the ball pushes back, to the point that it would “take your hand off” if you applied enough pushing force, Martire tells Popular Mechanics . That’s a sign of negative energy, and, though the Alcubierre drive design requires it, there’s no way to harness it.

Instead, regular old positive energy is more feasible for constructing the “ warp bubble .” As its name suggests, it’s a spherical structure that surrounds and encloses space for a passenger ship using a shell of regular—but incredibly dense—matter. The bubble propels the spaceship using the powerful gravity of the shell, but without causing the passengers to feel any acceleration. “An elevator ride would be more eventful,” Martire says.

That’s because the density of the shell, as well as the pressure it exerts on the interior, is controlled carefully, Fuchs tells Popular Mechanics . Nothing can travel faster than the speed of light, according to the gravity-bound principles of Albert Einstein’s theory of general relativity . So the bubble is designed such that observers within their local spacetime environment—inside the bubble—experience normal movement in time. Simultaneously, the bubble itself compresses the spacetime in front of the ship and expands it behind the ship, ferrying itself and the contained craft incredibly fast. The walls of the bubble generate the necessary momentum, akin to the momentum of balls rolling, Fuchs explains. “It’s the movement of the matter in the walls that actually creates the effect for passengers on the inside.”

Building on its 2021 paper published in Classical and Quantum Gravity —which details the same researchers’ earlier work on physical warp drives—the team was able to model the complexity of the system using its own computational program, Warp Factory. This toolkit for modeling warp drive spacetimes allows researchers to evaluate Einstein’s field equations and compute the energy conditions required for various warp drive geometries. Anyone can download and use it for free . These experiments led to what Fuchs calls a mini model, the first general model of a positive-energy warp drive. Their past work also demonstrated that the amount of energy a warp bubble requires depends on the shape of the bubble; for example, the flatter the bubble in the direction of travel, the less energy it needs.

THIS LATEST ADVANCEMENT suggests fresh possibilities for studying warp travel design, Erik Lentz, Ph.D., tells Popular Mechanics . In his current position as a staff physicist at Pacific Northwest National Laboratory in Richland, Washington, Lentz contributes to research on dark matter detection and quantum information science research. His independent research in warp drive theory also aims to be grounded in conventional physics while reimagining the shape of warped space. The topic needs to overcome many practical hurdles, he says.

Controlling warp bubbles requires a great deal of coordination because they involve enormous amounts of matter and energy to keep the passengers safe and with a similar passage of time as the destination. “We could just as well engineer spacetime where time passes much differently inside [the passenger compartment] than outside. We could miss our appointment at Proxima Centauri if we aren’t careful,” Lentz says. “That is still a risk if we are traveling less than the speed of light.” Communication between people inside the bubble and outside could also become distorted as it passes through the curvature of warped space, he adds.

While Applied Physics’ current solution requires a warp drive that travels below the speed of light, the model still needs to plug in a mass equivalent to about two Jupiters. Otherwise, it will never achieve the gravitational force and momentum high enough to cause a meaningful warp effect. But no one knows what the source of this mass could be—not yet, at least. Some research suggests that if we could somehow harness dark matter , we could use it for light-speed travel, but Fuchs and Martire are doubtful, since it’s currently a big mystery (and an exotic particle).

Despite the many problems scientists still need to solve to build a working warp drive, the Applied Physics team claims its model should eventually get closer to light speed. And even if a feasible model remains below the speed of light, it’s a vast improvement over today’s technology. For example, traveling at even half the speed of light to Alpha Centauri would take nine years. In stark contrast, our fastest spacecraft, Voyager 1—currently traveling at 38,000 miles per hour—would take 75,000 years to reach our closest neighboring star system.

Of course, as you approach the actual speed of light, things get truly weird, according to the principles of Einstein’s special relativity . The mass of an object moving faster and faster would increase infinitely, eventually requiring an infinite amount of energy to maintain its speed.

“That’s the chief limitation and key challenge we have to overcome—how can we have all this matter in our [bubble], but not at such a scale that we can never even put it together?” Martire says. It’s possible the answer lies in condensed matter physics, he adds. This branch of physics deals particularly with the forces between atoms and electrons in matter. It has already proven fundamental to several of our current technologies, such as transistors, solid-state lasers, and magnetic storage media.

The other big issue is that current models allow a stable warp bubble, but only for a constant velocity. Scientists still need to figure out how to design an initial acceleration. On the other end of the journey, how will the ship slow down and stop? “It’s like trying to grasp the automobile for the first time,” Martire says. “We don’t have an engine just yet, but we see the light at the end of the tunnel.” Warp drive technology is at the stage of 1882 car technology, he says: when automobile travel was possible, but it still looked like a hard, hard problem.

The Applied Physics team believes future innovations in warp travel are inevitable. The general positive energy model is a first step. Besides, you don’t need to zoom at light speed to achieve distances that today are just a dream, Martire says. “Humanity is officially, mathematically, on an interstellar track.”

Before joining Popular Mechanics , Manasee Wagh worked as a newspaper reporter, a science journalist, a tech writer, and a computer engineer. She’s always looking for ways to combine the three greatest joys in her life: science, travel, and food.

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Warp drives: Physicists investigate faster-than-light space travel

The closest star to Earth is Proxima Centauri. It is about 4.25 light-years away, or about 25 trillion miles (40 trillion kilometers). The fastest ever spacecraft, the now- in-space Parker Solar Probe will reach a top speed of 450,000 mph. It would take just 20 seconds to go from Los Angeles to New York City at that speed, but it would take the solar probe about 6,633 years to reach Earth’s nearest neighboring solar system.

If humanity ever wants to travel easily between stars, people will need to go faster than light. But so far, faster-than-light travel is possible only in science fiction.

In Issac Asimov’s Foundation series , humanity can travel from planet to planet, star to star or across the universe using jump drives. As a kid, I read as many of those stories as I could get my hands on. I am now a theoretical physicist and study nanotechnology, but I am still fascinated by the ways humanity could one day travel in space.

Some characters – like the astronauts in the movies “Interstellar” and “Thor” – use wormholes to travel between solar systems in seconds. Another approach – familiar to “Star Trek” fans – is warp drive technology. Warp drives are theoretically possible if still far-fetched technology. Two recent papers made headlines in March when researchers claimed to have overcome one of the many challenges that stand between the theory of warp drives and reality.

But how do these theoretical warp drives really work? And will humans be making the jump to warp speed anytime soon?

Compression and expansion

Physicists’ current understanding of spacetime comes from Albert Einstein’s theory of general relativity . General relativity states that space and time are fused and that nothing can travel faster than the speed of light. General relativity also describes how mass and energy warp spacetime – hefty objects like stars and black holes curve spacetime around them. This curvature is what you feel as gravity and why many spacefaring heroes worry about “getting stuck in” or “falling into” a gravity well. Early science fiction writers John Campbell and Asimov saw this warping as a way to skirt the speed limit.

What if a starship could compress space in front of it while expanding spacetime behind it? “Star Trek” took this idea and named it the warp drive.

In 1994, Miguel Alcubierre, a Mexican theoretical physicist, showed that compressing spacetime in front of the spaceship while expanding it behind was mathematically possible within the laws of General Relativity . So, what does that mean? Imagine the distance between two points is 33 feet (10 meters). If you are standing at point A and can travel one meter per second, it would take 10 seconds to get to point B. However, let’s say you could somehow compress the space between you and point B so that the interval is now just one meter. Then, moving through spacetime at your maximum speed of one meter per second, you would be able to reach point B in about one second. In theory, this approach does not contradict the laws of relativity since you are not moving faster than light in the space around you. Alcubierre showed that the warp drive from “Star Trek” was in fact theoretically possible.

Proxima Centauri here we come, right? Unfortunately, Alcubierre’s method of compressing spacetime had one problem: it requires negative energy or negative mass.

A negative energy problem

Alcubierre’s warp drive would work by creating a bubble of flat spacetime around the spaceship and curving spacetime around that bubble to reduce distances. The warp drive would require either negative mass – a theorized type of matter – or a ring of negative energy density to work. Physicists have never observed negative mass, so that leaves negative energy as the only option.

To create negative energy, a warp drive would use a huge amount of mass to create an imbalance between particles and antiparticles. For example, if an electron and an antielectron appear near the warp drive, one of the particles would get trapped by the mass and this results in an imbalance. This imbalance results in negative energy density. Alcubierre’s warp drive would use this negative energy to create the spacetime bubble.

But for a warp drive to generate enough negative energy, you would need a lot of matter. Alcubierre estimated that a warp drive with a 100-meter bubble would require the mass of the entire visible universe .

In 1999, physicist Chris Van Den Broeck showed that expanding the volume inside the bubble but keeping the surface area constant would reduce the energy requirements significantly , to just about the mass of the Sun. A significant improvement, but still far beyond all practical possibilities.

A sci-fi future?

Two recent papers – one by Alexey Bobrick and Gianni Martire and another by Erik Lentz – provide solutions that seem to bring warp drives closer to reality.

Bobrick and Martire realized that by modifying spacetime within the bubble in a certain way, they could remove the need to use negative energy. This solution, though, does not produce a warp drive that can go faster than light.

Independently, Lentz also proposed a solution that does not require negative energy. He used a different geometric approach to solve the equations of general relativity, and by doing so, he found that a warp drive wouldn’t need to use negative energy. Lentz’s solution would allow the bubble to travel faster than the speed of light.

It is essential to point out that these exciting developments are mathematical models. As a physicist, I won’t fully trust models until we have experimental proof. Yet, the science of warp drives is coming into view. As a science fiction fan, I welcome all this innovative thinking. In the words of Captain Picard , things are only impossible until they are not.

The People’s Spaceship: NASA, the Shuttle Program, and Public Engagement after Apollo

Why do pictures of Earth taken from the Moon show a black sky with no stars?

Oleg Kononenko reaches a record-setting 1,000 days in space

Boeing starliner launches nasa astronauts on mission to the iss.

What Is Polaris Dawn? The upcoming SpaceX mission, explained

Why Boeing’s Starliner launch is an important milestone for commercial spaceflight

SpaceX adds tourism offering to website

Astronauts have a surprising ability to gauge distances in space

What happens if someone dies in space?

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Hubble will change how it points, but NASA says 'great science' will continue

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The Hubble Space Telescope in orbit in 1999, just after a servicing mission by astronauts. NASA hide caption

The Hubble Space Telescope is suffering the kinds of aches and pains that can come with being old, and NASA officials say they’re shifting into a new way of pointing the telescope in order to work around a piece of hardware that’s become intolerably glitchy.

Officials also announced that, for now, they’ve decided not to pursue a plan put forward by a wealthy private astronaut who wanted to go to Hubble in a SpaceX capsule, in a mission aimed at extending the telescope’s lifespan by boosting it up into a higher orbit and perhaps even adding new technology to enhance its operations.

“Even without that reboost, we still expect to continue producing science through the rest of this decade and into the next,” Mark Clampin , director of the astrophysics division in NASA’s science mission directorate, told reporters in a teleconference on Tuesday.

Because of atmospheric drag, the bus-sized telescope is slowly drifting down towards Earth. If nothing is eventually done to raise it up, it will likely plunge down into the atmosphere and mostly burn up in the mid-2030’s.

Private mission to save the Hubble Space Telescope raises concerns, NASA emails show

That’s one reason why NASA was so interested when Jared Isaacman, who has previously gone to orbit in a SpaceX capsule, suggested mounting a mission to Hubble as part of a series of technology demonstration spaceflights he has planned.

NASA and SpaceX jointly worked on a feasibility study to see what might be possible for Hubble. The telescope has been in orbit since 1990 and was last repaired 15 years ago, by astronauts who went up in NASA’s space shuttles, which are now museum exhibits.

NASA’s Clampin told reporters that “after exploring the current commercial capabilities, we are not going to pursue a reboost right now.”

He said the assessment of Isaacman’s proposal raised a number of considerations, including potential risks such as “premature loss of science” if Hubble accidentally got damaged.

NASA officials stressed that Hubble’s instruments are healthy and the telescope remains incredibly productive.

“We do not see Hubble as being on its last legs,” said Patrick Crouse , project manager for the Hubble Space Telescope at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We do think it's a very capable observatory and poised to do exciting things.”

But it will have to do those exciting things with a new way of operating the system it uses for pointing at celestial objects.

That’s because officials have abandoned their efforts to use a glitchy gyroscope that has repeatedly forced the telescope to suspend science and go into “safe” mode in recent months.

Hubble’s pointing system is so precise, NASA says it is the equivalent of being able to keep a laser shining on a dime over 200 miles away for however long Hubble takes a picture – up to 24 hours. This system has long relied on using three gyroscopes at a time.

Now, though, to avoid having to use the sketchy gyro, NASA says Hubble will shift into a one-gyroscope mode of operation, a contingency plan that’s been around for years.

“After completing a series of tests and carefully considering our options, we have made the decision that we will transition Hubble to operate using only one of its three remaining gyros,” Clampin said. “Operationally, we believe this is our best approach to support Hubble science through this decade and into the next.”

The scattered stars of the globular cluster NGC 6355, that resides in our Milky Way, seen in this image from the Hubble Space Telescope ESA/Hubble & NASA, E.Noyola, R. Cohen hide caption

Using only one healthy gyroscope, and keeping one in reserve as a backup, will let the telescope continue to return gorgeous images of the universe, with some limitations. Hubble will be less efficient, for example, and it won’t be able to track moving objects that are close to Earth, within the orbit of Mars.

But Clampin said that “most of the observations it takes will be completely unaffected by this change.”

Astronomers still clamor to use Hubble, with proposals for what to observe far exceeding the available telescope time.

The launch of the James Webb Space Telescope in 2021 did not render Hubble obsolete, as the two telescopes capture different kinds of light.

NASA's Voyager 1 spacecraft is talking nonsense. Its friends on Earth are worried

Eventually, NASA will have to decide what to do about Hubble, given that some of its large components would survive re-entering the Earth’s atmosphere. The space agency has long considered sending up some kind of mission that would control its descent and ensure that any Hubble rubble would safely fall into an ocean.

Adding such a propulsion unit would mean that NASA could also boost Hubble’s orbit, enabling it to live longer and take advantage of whatever instruments continued to work. But NASA’s Clampin suggested that there is time to consider options.

“Our latest prediction is that the earliest Hubble would re-enter the Earth's atmosphere is the mid-2030s,” he said. “So we are not going to be seeing it come down in the next couple of years.”

• Hubble Space Telescope

In a Different Light

Astronomers use light and the different wavelengths or colors at which it radiates to uncover the mysteries of the universe. Each point, or pixel, in an astronomical image may represent temperature, a wavelength of light, or the intensity of the signal. Each color brings into view an otherwise invisible universe.

VISIBLE & INFRARED

Mystic Mountain

Revealing the Difference Between Visible and Infrared Light: These images of Mystic Mountain – a pillar of gas, dust, and newborn stars in the Carina Nebula – show how observations taken in visible and infrared light reveal different details of an object.

Visible Light

Human eyes can see only a small portion of the range of radiation given off by the objects around us. We call this wide array of radiation the electromagnetic spectrum, and the part we can see “visible light.”

By only seeing visible light, we miss out on the information conveyed by other types of radiation. Other Earth creatures can see some of the spectrum we are blind to. Certain fish, bullfrogs and snakes, for instance, can see infrared radiation, which helps them find prey through murky water or in the dark. Butterflies and some species of birds can see ultraviolet light, which helps them identify certain markings on mates.

When it comes to cosmic objects, key information is revealed by different portions of the electromagnetic spectrum. Telescopes are designed to capture different portions of this spectrum, providing more information than the human eye could detect on its own. The Hubble Space Telescope can detect a portion of infrared and ultraviolet wavelengths as well as visible light.

Because our atmosphere blocks or partially absorbs certain wavelengths, Hubble’s position 320 miles above Earth’s surface puts it in a location where it can capture details of objects that would be difficult or impossible for ground-based telescopes to observe.

Hubble has also worked in concert with other telescopes, combining its observations with those of wavelengths observed by other space telescopes. In these cases, the combined or contrasting images provide more information about the object than either image could alone.

Infrared Light

The short wavelengths of visible light make them prone to bumping into particles in their path, scattering the light and blocking it from progressing. Infrared-light wavelengths are longer and more likely to slip between particles. In space, this allows infrared wavelengths to penetrate all but the densest regions of dust. By viewing infrared light, we can essentially look through cosmic clouds of gas and dust to the objects behind and within them. Infrared light is also emitted by warm material too dim to glow significantly in visible light, and can allow us to see those objects.

Seeing infrared light is the only way to view many cosmic objects. As the light from the universe’s most distant galaxies travels through space, it’s stretched by the expansion of space. By the time the light reaches Earth, that stretching process has transformed short wavelengths of visible and ultraviolet light into the longer wavelengths of infrared light. Only telescopes that can detect infrared light can see those faraway galaxies.

Visible & infrared

Eagle Nebula

Many will recognize this popular image of a portion of the Eagle Nebula, but there's also a lesser-known second image that reveals more about this cosmic landscape. Move the slider from left to right to reveal the image in visible and infrared light.

Many will recognize this popular image of a portion of the Eagle Nebula, but there's also a lesser-known second image that reveals more about this cosmic landscape. The famous visible-light image shows 5-light-year-tall pillars of cold hydrogen gas laced with dust, where stars are being born. Radiation from nearby stars, located off the top of the image, illuminate the pillars and heat the gas, which evaporates into space as streamers from the tips of the pillars. In the second Hubble image, infrared light flows through the clouds, revealing a vast number of the stars both past the nebula and blazing to life within it. Note the bright, newborn stars now obvious in the tops of the pillars in the infrared image.

Lagoon Nebula

Hubble's visible-light image (left) of the Lagoon nebula reveals colorful swirls and dark pillars of gas and dust. The telescope's near-infrared image unveils stars within the cloud as well thousands of background stars.

In the visible-light image, the Lagoon Nebula is a nearly impenetrable cloud of gas and dust. Buried in its center is a hint of a monster-sized young star 200,000 times brighter than the Sun whose radiation is carving and shaping the nebula around it. Infrared light penetrates the nebula to unveil that blazing star, known as Herschel 36, as well as the myriad of background stars behind the nebula and many that were cloaked in its dust.

Carina Nebula Pillar

Hubble's visible-light image (left) of the Carina Nebula holds small bright dots that hint at the stars forming within. The telescope's near-infrared image (right) reveals these stars in all of their brilliant glory.

This pillar in the Carina Nebula hides newborn stars in its depths, cloaked in layers of gas and dust. In the visible-light image, we get a hint of what’s inside. Thin puffs of material and wispy clouds appear to sprout from a dark notch in the pillar’s center – a jet of matter being flung into space by a newborn star. The infrared image reveals both the star and its 10-light-year-long jet, which is pouring into space at around 850,000 miles per hour.

GOODS North

The GOODS North image includes one of the earliest objects ever observed – GN-z11, seen as it was 13.4 billion years in the past. The distant galaxy’s light arrives in our corner of the universe after having been stretched by its trip across the expanding universe into infrared wavelengths. Because this light has been traveling for so long, it shows us the galaxy as it was just 400 million years after the Big Bang. This video zooms into the GOODS North image starting with its location in the sky and ending with our infrared glimpse of GN-z11.

Ultraviolet Light

High-energy ultraviolet radiation is mostly blocked by Earth’s atmosphere – and that’s good for us, since we can’t survive too much of it. But because we can’t see it, we’re missing out on some spectacular cosmic phenomena, including light from the hottest and youngest stars embedded in local galaxies, and auroras that glow on the outer planets of our solar system. Ultraviolet observations can also help us determine the composition of the atmospheres of planets beyond our solar system.

Hubble's visible-light image (left) of Saturn reveals the planets rings and atmospheric cloud bands. The telescope's ultraviolet view (right) pulls out more detail in the planets ring system, while showcasing a bright atmospheric cloud band (seen in yellow) near the planet's equator.

The bands circling Saturn in these images are actually haze and cloud layers, composed of different particles of gas. Here both the visible and ultraviolet images of Saturn are portrayed in false colors to make differences stand out. Some particles reflect ultraviolet light more than visible light, causing parts of Saturn to appear brighter in the ultraviolet than the visible. These images show how certain gases are more prominent in the lower atmosphere than the upper, and vice versa. Only by combining and comparing these different images, in a set such as this one, can researchers interpret the data and better understand the planet.

Auroras are caused by high-energy particles that travel along a planet's magnetic poles, where they excite atmospheric gases and cause them to glow. On Earth, the particles collide with oxygen and nitrogen gases to give off visible light in multiple shimmering colors. On the outer planets, they interact with hydrogen-heavy atmospheres, causing an ultraviolet light show visible to Hubble – as in this time-lapse series of images of ultraviolet auroras shimmering at Jupiter's north pole.

Comet Impacts on Jupiter

In 1994, the pieces of the shattered comet Shoemaker-Levy 9 plunged into Jupiter while Hubble watched. In images taken in visible light (left), the impact areas appear as relatively faint smudges scattered over the southern hemisphere of the gas planet. The ultraviolet image of Jupiter (right), however, shows the large quantities of UV-absorbing dust spreading high in the atmosphere following the impacts. Because the fine particles are easier to see in ultraviolet light, this image gives us a clearer picture of the comet residue and materials thrown from Jupiter’s lower atmosphere into the upper atmosphere by the impact. The dark dot near the top of the ultraviolet image is Jupiter's moon Io.

Hubble Ultra Deep Field (2014)

Astronomers captured ultraviolet light with Hubble to provide this more-comprehensive 2014 version of its Hubble Ultra Deep Field image, which had previously consisted of visible- and infrared-light observations taken between 2003–2009. This image contains all three wavelengths: visible, infrared and ultraviolet.

Ultraviolet light comes from the hottest, largest and youngest stars. By observing ultraviolet light, scientists can see which galaxies are forming stars and where the stars are forming within those galaxies.

Ultraviolet and visible light from the farthest galaxies is stretched into infrared light as it travels across the expanding universe. But for a distance extending from about 5 billion to 10 billion light-years – showing galaxies from the period when most of the stars in the universe were born – ultraviolet-light observations are key.

Collaborations with Other Telescopes

Telescopes often specialize in specific wavelengths of light. The infrared-studying Spitzer Space Telescope, the Chandra X-ray Observatory spacecraft, and the National Radio Astronomy Observatory on Earth are examples of observatories with this targeted focus. Hubble has worked in concert with other telescopes to create images of cosmic objects that incorporate a wide range of wavelengths, each image a piece of a puzzle that eventually reveals a complete view of the object and conveys unique information about the processes taking place.

The Crab Nebula

This composite image of the Crab Nebula – loops of gas and debris cast off by the explosive death of a star, energized by a compressed stellar core called a neutron star at its heart – was created by combining the data from five telescopes, spanning nearly the entirety of the electromagnetic spectrum. The red, radio-light view shows how the neutron star’s “wind” of charged particles energizes the nebula, causing it to emit radio waves. The yellow, infrared image highlights the glow of dust particles absorbing ultraviolet and visible light. The green Hubble image offers a visible-light view of hot filamentary structures throughout the nebula. The blue, ultraviolet image and purple, X-ray image show the effects of an energetic cloud of electrons driven by the rapidly rotating neutron star at the nebula’s center.

Visible & Radio

Hubble's visible-light image (left) of Hercules A is superimposed with the radio wavelength view (right) of the galaxy revealing powerful jets ejected by the supermassive black hole at the galaxy's core.

This visible-light image from Hubble shows a seemingly ordinary elliptical galaxy surrounded by other, smaller galaxies. But in that galaxy’s center lies a black hole as massive as 2.5 billion suns. The gravitational energy and fast rotation of the supermassive black hole is creating enormous jets, focused by magnetic fields, that are 1.5 million light-years long and far surpass the size of the galaxy they emanate from. The jets are made of high-energy plasma beams, subatomic particles and magnetic fields shot at nearly the speed of light from the vicinity of the black hole. Because they emit radio waves, they’re invisible to the human eye and Hubble, but fill the combined radio and visible-light image. Hercules A is one of the brightest extragalactic radio sources in the entire sky.

Visible & X-ray

Supernova Remnant 0509-67.5

Hubble's visible-light image (left) of the supernova remnant known as SNR 0509-67.5 is a delicate sphere of expanding gas and dust. The composite visible and X-ray image (right) reveals the X-ray glow of material heated by the blast wave.

This bubble is a supernova remnant – what’s left of a star that exploded nearly 400 years ago. As the blast from the explosion expands, the ejected material travels outward at more than 11 million miles (17.7 million km) per hour. In the visible-light image taken by Hubble, the glowing pink shell is created when the supernova blast wave compresses and expands the surrounding gas. In the combined visible-light and X-ray image, we also see the soft green and blue hues of material that has been heated to millions of degrees until it glows in X-rays.

Hubble Science Highlights

Learn about Hubble's scientific discoveries.

Monster Black Holes are Everywhere

Hubble found that supermassive black holes lie at the heart of nearly every galaxy.

Studying the Outer Planets and Moons

Hubble’s systematic observations chart the ever-changing environments of our solar system's giant planets and their moons. about the history of Glenn Research Center.

Exploring the Birth of Stars

Hubble’s near-infrared instruments see through the gas and dust clouds surrounding newborn stars.

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Impact & Benefits

Hubble's mission is to capture observations of the universe, but its technology would alter life on the ground in unique and unexpected ways.

Hubble Discoveries

Hubble has changed our understanding of the universe and transformed the study of astronomy.

Hubble at Home Activities

Find your Hubble birthday image, take interactive tours, play games, and explore the universe with Hubble.

Hubble E-Books

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Time may be an illusion created by quantum entanglement

The true nature of time has eluded physicists for centuries, but a new theoretical model suggests it may only exist due to entanglement between quantum objects

By Karmela Padavic-Callaghan

31 May 2024

Where does time come from?

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Time may not be a fundamental element of our physical reality. New calculations add credence to the idea that it emerges from quantum entanglement , in which two objects are so inextricably linked that disturbing one disrupts the other, no matter how distant they are.

The mathematician who worked out how to time travel

“For centuries, time has entered physics as an essential ingredient that is not to be questioned. It is so deeply rooted in our conception of reality that people thought…

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State Machines, Light Switches, and Space Travel with Stateless and .NET 8

State machines are so integral to software development that they often seem invisible to developers. They are used so frequently yet abstracted away through APIs and syntax that many developers don’t directly deal with them. However, we’d like to.

At their core, state machines are systems with finite inputs and deterministic pathways. While they can be complex, the basic structure of nodes and vertices makes them more approachable than they may initially seem.

In this post, I’ll guide you through the process of building two state machines using the .NET library Stateless . We’ll also discuss effective strategies for incorporating state machines into your code.

Getting Started with Stateless

To start using Stateless , you’ll need to install the latest version of the package using NuGet.

From here, you will use the StateMachine class to define the state object and the triggers that mutate the machine’s state.

The example used in the Stateless documentation is that of a phone.

You’ll notice that the StateMachine has two generic arguments: one for the state and the other for the trigger. These types can be any .NET type, but they’re enum types in this sample.

Let’s build something closer to how I recommend using Stateless.

The Light Switch State Machine Example

This example shows a Widget class that always has a deterministic state of being On or Off . The trigger for our Widget is to Press . While we could implement the state machine as we did previously, I recommend encapsulating state machines within a class.

Why? It’s much easier to consume these class instances and have the machine’s state exposed through properties and interactions to exist as a method call. In the “real world,” we typically don’t understand the internal behavior of the abstractions we interact with; we only observe the outcome of our interactions.

In the case of this implementation, Stateless is managing the state of our Widget , and we know it will be consistent with the behavior we define in the constructor.

Let’s see it in action!

This is a neat technique, but admittedly simple. Let’s go to space next.

Space Travel with State Machines

A challenging concept when working with state machines is managing the state. Luckily, with Stateless, extracting, storing, and rehydrating state is straightforward.

Let’s create a state machine to travel through our solar system.

We’ve done a few things with this state machine that are more complex than our Widget example.

• The initial state of our StateMachine can be set at instantiation time through the constructor.
• There are two triggers of In and Out , both of which can be fired through matching methods.
• The constructor defines how travel can occur from one planet to another, with the Sun and Pluto being re-entry nodes. (You can’t leave the solar system).
• Each transition calculates the distance between two bodies, regardless of the state change.

Let’s do some space travel!

Running the application, we get the sample output.

Neat! What about seeing our travel path?

Graphing your State Machines

At any point in time, you can use the UmlDotGraph static class in the Stateless library to output the graph to a string value.

Our light switch sample produces the following DotGraph that can be turned into an SVG.

These visualizations can be helpful for documentation or diagnosing issues when exceptions occur in the state machine.

Stateless is a very cool library worth checking out. It can add the necessary structure to otherwise complex workflows. I highly recommend encapsulating the StateMachine class within a container class; otherwise, you’ll be dealing with some unwieldy APIs.

A slew of APIs not covered in this post can help you determine if an action can be executed, what next steps are permitted, and error handling for unhandled triggers. It is a well-thought-out library, and I hope you try it.

As always, thanks for reading and sharing my posts. Cheers.

About Khalid Abuhakmeh

Khalid is a developer advocate at JetBrains focusing on .NET technologies and tooling.

Blazor HTML Forms, Submitting, and Antiforgery Tokens

James Webb Space Telescope discovers 717 ancient galaxies that flooded the universe with 1st light

93% of the newfound galaxies that Webb spotted had never been seen before.

The James Webb Telescope (JWST or Webb) has unveiled hundreds of ancient galaxies that could be among the first members of the universe — a leap from only a handful that were previously known to exist at the time.

As early as 600 million years after the Big Bang , these very young galaxies flaunted complex structures and clusters of star formation, a new study reports. The study is part of an international collaboration called the JWST Advanced Deep Extragalactic Survey (JADES), which gathered a month's worth of observations from two tiny patches in the sky: One in the Ursa Minor constellation and another in the direction of the Fornax cluster . Within this region were over 700 newly discovered young galaxies that reveal with the cosmos looked like in its earliest

"If you took the whole universe and shrunk it down to a two hour movie, you are seeing the first five minutes of the movie," Kevin Hainline, an assistant research professor at the Steward Observatory in Arizona and a lead author of the new study, said while announcing the discovery on Monday (June 5) at the 242nd meeting of the American Astronomical Society being held in Albuquerque and online. "These are the galaxies that are starting the process of making the elements and the complexity that we see in the world around us today."

These new findings shed light on how the first galaxies and stars formed, creating the rich catalog of elements observed in the universe today .

Related: James Webb Space Telescope (JWST) — A complete guide

In those five minutes alone, which marks the universe to be between 370 million and 650 million years old, Hainline's and his colleagues studying Webb's data found 717 young galaxies — which turns out to be higher than previous predictions — with all of them already spanning thousands of light-years, sporting complex structures, and birthing stars in multiple clusters. 

"Previously, the earliest galaxies we could see just looked like little smudges. And yet those smudges represent millions or even billions of stars at the beginning of the universe," Hainline said in a statement . "Now, we can see that some of them are actually extended objects with visible structure."  

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Together, the two regions used in this study are referred to as GOODS-South, an acronym for The Great Observatories Origins Deep Survey , and have been extensively studied by nearly all major space telescopes, including Hubble , the Chandra X-Ray Observatory and NASA's now-retired Spitzer .

Despite this previous scrutiny, 93% of the newfound galaxies that Webb spotted during JADES had never been seen before.

"What we were seeing before were just the brightest, most extreme examples of bright galaxies in the early universe," Hainline said during his presentation on Monday. "Now we are really probing down to more normal, everyday galaxies in a turbulent young universe."

Precisely how that chaotic, very dusty environment cleared up to become the transparent cosmos we see today has long been debated. A leading theory is that this phase of evolution of the universe, called the Epoch of Reionization , occurred some 400,000 years after the Big Bang, when the first generation of stars — thought to be 30 to 300 times our sun's mass and millions of times more bright — formed and flooded the opaque universe with its first light . 

That ultraviolet starlight reionized the universe by splitting its abundant hydrogen atoms into protons and electrons, a process that lasted until one billion years after the Big Bang. However, few astronomers say outflows from supermassive black holes , similar to the one that resides in the heart of our Milky Way, could have triggered the escape of ultraviolet radiation from galaxies and thus played a more important role in cosmic evolution than previously thought.

Now, a second team from the JADES program that has been studying galaxies that existed between 500 to 850 million years after the Big Bang, or between five to eight minutes of the two-hour movie describing the universe, thinks it has an answer to the long-standing question.

"In this next scene of the universe, we are starting to actually see the impact of galaxy formation on the composition of the large scale universe," Ryan Endsley, a postdoctoral researcher at the University of Texas who led the second study, said at the news conference on Monday. "Galaxies in the very early universe were just far more chaotic in general in how they formed stars."

Endsley's team studied the signs of star formation in those very early galaxies, which provided insight into how starlight ionized the gas within those galaxies. The team found that one in six galaxies at the time showed extreme line emissions in the galaxy's spectra, a feature that atoms ionized by starlight radiate when they have cooled down and combined with other molecules.

Those emission lines are evidence that early galaxies were actively birthing stars, which then pumped "torrents of ultraviolet photons" into their respective galaxies. This way, the universe's early stars became the main drivers of cosmic reionization, Endsley said.

"These extreme emission lines are actually relatively common in the very early universe," he said during his presentation. "Almost every single galaxy that we are finding shows these unusually strong emission line signatures indicating intense recent star formation," he added in the statement. "These early galaxies were very good at creating hot, massive stars."

 —  James Webb Space Telescope spies earliest complex organic molecules in the universe

—   James Webb Space Telescope spots huge galactic protocluster in the early universe (photo)

 —   Why do some James Webb Space Telescope images show warped and repeated galaxies?

From the same emission lines, Endsley's team also inferred that galaxies in the early universe birthed stars in short bursts followed by quiescent periods.

"All of a sudden you would have tens of suns worth of solar masses being assembled all at once in these early galaxies," Endsley told reporters at the news briefing on Monday. "That's really important for our understanding of how reionization happened because these hot massive stars were very efficient producers of these ultraviolet photons that we needed in order to ionize all the hydrogen in the early universe." 

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: [email protected].

Sharmila Kuthunur is a Seattle-based science journalist covering astronomy, astrophysics and space exploration. Follow her on X @skuthunur.

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• rod "As early as 600 million years after the Big Bang, these very young galaxies flaunted complex structures and clusters of star formation, a new study reports. The study is part of an international collaboration called the JWST Advanced Deep Extragalactic Survey (JADES), which gathered a month's worth of observations from two tiny patches in the sky: One in the Ursa Minor constellation and another in the direction of the Fornax cluster. Within this region were over 700 newly discovered young galaxies that reveal with the cosmos looked like in its earliest." JADES is getting interesting. The Cosmos in its Infancy: JADES Galaxy Candidates at z > 8 in GOODS-S and GOODS-N, https://arxiv.org/abs/2306.02468, 04-June-2023. "We present a catalog of 717 candidate galaxies at z>8 selected from 125 square arcminutes of NIRCam imaging as part of the JWST Advanced Deep Extragalactic Survey (JADES)." My observation. No metal free gas or the pristine gas from postulated BBN is seen that is said to fill the early universe, dust is reported in JADES paper and more study to show metallicity. Cosmology calculators show light-time of some 13 Gyr or a bit more for z=8.0 and age of universe at z=8, 0.646 Gyr. Some other discussions on forums about JADES too and metal content, https://forums.space.com/threads/james-webb-space-telescope-spies-earliest-complex-organic-molecules-in-the-universe.61665/ Reply
• Atlan0001 Still waiting to see the precursor Milky Way at 600 million years after the Big Bang and the Milky Way's whole evolutionary, revolutionary, light trail from there, then, to here, now. I would be willing to bet if a ship could travel fast enough it would trail the Milky Way from here, now, clear to the horizon there, then, at a distance from the ship of about 10 to 13 billion-odd light years (oops a circling around). Or maybe it couldn't actually (so no bet). Probably it wouldn't, couldn't, hold . . . couldn't stay . . . the course, into such a tight, and ever tighter and tighter, turning curvature it would have to take into that vortex to keep the Milky Way's light time history trail of crumbs lined up in the rearview mirror. The ship would literally be tossed, thrown, sideways into gravity's outland infinity and out of the Milky Way's spacetime universe altogether into some other. Actually, where it would end up in any case. Reply

Atlan0101 said: Still waiting to see the precursor Milky Way at 600 million years after the Big Bang and the Milky Way's whole evolutionary, revolutionary, light trail from there, then, to here, now. I would be willing to bet if a ship could travel fast enough it would trail the Milky Way from here, now, clear to the horizon there, then, at a distance from the ship of about 10 to 13 billion-odd light years (oops a circling around). Or maybe it couldn't actually (so no bet). Probably it wouldn't, couldn't, hold . . . couldn't stay . . . the course, into such a tight, and ever tighter and tighter, turning curvature it would have to take into that vortex to keep the Milky Way's light time history trail of crumbs lined up in the rearview mirror. The ship would literally be tossed, thrown, sideways into gravity's outland infinity and out of the Milky Way's spacetime universe altogether into some other. Actually, where it would end up in any case.

rod said: My observation. No metal free gas or the pristine gas from postulated BBN is seen that is said to fill the early universe, dust is reported in JADES paper and more study to show metallicity.

Atlan0101 said: Still waiting to see the precursor Milky Way at 600 million years after the Big Bang and the Milky Way's whole evolutionary, revolutionary, light trail from there, then, to here, now.

rod said: However, redshifts of 1.4 or larger, in GR math (cosmology calculators will demonstrate this), show space expanding faster than c velocity and comoving radial distances so far away, we cannot observe them today on Earth.

• Atlan0001 If the Big Bang Horizon blows, spews, nothing but microcosmic photons, nothing but light, at the speed of light and time, then it is no wonder that the universe is loaded down with light streams running macrocosmic light time histories down every corridor and around every corner of it. All light time history crossroads won't reach to every single crossroad point of a 4-dimensional chessboard multiverse regardless of some thinking we should be capable of observing all of it, all of the multiverse universe, all at once at a every center-0-point of it . . . most especially a centric Earth so centrically divine in the universe. Since we observe our universe 1-dimensionally, even stretching to 2-dimensionality, they say that that single-sided 2-dimensional map, flattened cones of light time histories, is the whole territory mapped, if not the whole territory itself observed and observable. We observe no more than a local-relative finite part of it . . . and even then, the only current, concurrent, horizon observable is the Horizon we are quantum entangled in and with ("spooky action at a distance"). Few have minds stretched far enough to realize that the map can never be, and will never be, the territory. And, though the collapsed constant of Horizon uses the infinitely vast resource of the infinity of universes closed up to it, in it, behind it, beyond the Horizon, influentially creatively, it is no more or less than the Planck / Big Bang / Black Hole Horizon. And it isn't any 40-billion light years away. The collapsed constant (the cosmological constant (/\/)) -- the absolute collapse of Complexity and Chaos in Horizon -- is and will be a collapse 14-billion light years, 14-billion years both past (into future) and future (into past), away from 0-point center anywhere and everywhere in infinity . . . and that every 0-point center is quantum entangled in and with (per Einstein's mind's eye trip to the Horizon, and per Hawking's "Grand Central Station" -- and Station clock, exactly the same place just viewed, pictured, differently). It doesn't go away from point of collapse, neither as the Planck Horizon down and in, nor as the Big Bang Horizon up and out, one and the same constant of collapsing, collapsed, Horizon of Complexity and Chaos down and in and up and out. ----------------------------- "Brevity may the soul of wit, but repetition is the heart of instruction." -- Gen. George S. Patton, Jr. Reply
• rod Other sites reporting on the 717 *early galaxies* and JADES. JAMES WEBB SPACE TELESCOPE UNCOVERS HUNDREDS OF GALAXIES IN EARLY UNIVERSE, https://skyandtelescope.org/astronomy-news/james-webb-space-telescope-uncovers-hundreds-of-galaxies-in-early-universe/ "There’s a lot more to be gleaned from the JADES sample as JWST continues its observations, such as a better understanding of the galaxies’ shapes and sizes. In addition, while stars (and associated dust) dominated the press conference, these galaxies’ central black holes are waiting their turn for center stage. “I think that there are some really exciting examples of active supermassive black holes that people didn't necessarily expect to exist in this very early episode of the universe,” Endsley says. “It is something we really need to start taking into consideration as we move forward.” In the meantime, JWST has already painted a chaotic picture of the universe’s earliest years." As I said before, JADES is getting interesting. The Cosmos in its Infancy: JADES Galaxy Candidates at z > 8 in GOODS-S and GOODS-N, https://arxiv.org/abs/2306.02468, 04-June-2023. "We present a catalog of 717 candidate galaxies at z>8 selected from 125 square arcminutes of NIRCam imaging as part of the JWST Advanced Deep Extragalactic Survey (JADES)." My observation. No metal free gas or the pristine gas from postulated BBN is seen that is said to fill the early universe, dust is reported in JADES paper and more study required apparently to show metallicity. Cosmology calculators indicate light time of some 13 Gyr or a bit more for z=8.0 and age of universe at z=8, 0.646 Gyr. At some point, BB cosmology must show that such gas clouds postulated in theory, were indeed in nature. This includes H in the CMBR, He, and pristine gas clouds for the cosmic dark ages postulated in BB model before Population III stars formed, including showing Population III stars as real, not just simulation models. Using my telescopes, I can see the Galilean moons moving around Jupiter. I am waiting for the definitive paper and report showing the pristine gas clouds that are considered metal free. JADES is not showing this yet apparently. Reply

rod said: "Still waiting to see the precursor Milky Way at 600 million years after the Big Bang and the Milky Way's whole evolutionary, revolutionary, light trail from there, then, to here, now." Atlan0101, as I understand Big Bang cosmology, the large redshift *galaxies* are much smaller sizes and masses than M31 I see in my telescopes. The tiny evolved into the big over more than 13 Gyr in cosmology :) However, redshifts of 1.4 or larger, in GR math (cosmology calculators will demonstrate this), show space expanding faster than c velocity and comoving radial distances so far away, we cannot observe them today on Earth. Hence, we do not know how any of these *early tiny galaxies* evolved along their comoving radial distances (or even if any still exist out there, far, far away). Something I find commonly not pointed out to the public IMO, at least not clearly.

• Unclear Engineer I think the distinction between what we are seeing now, from Earth, and where the objects that emitted that light are now, gets confused with where those objects were when they emitted the light we are seeing now. Because we think we can see what is now microwave radiation emitted back at the time when atoms formed and allowed photons to travel freely through space, it seems that we should be able to detect radiation that was emitted later in time than 13.4 billion years ago, when the microwave background is thought to have been released. The potential catch in that idea is whether the atomic hydrogen blocked photons of various wavelengths to the extent that they would have blocked our view from here and now. The popular media gets that all messed up, talking about how the "dark ages" before stars developed were caused by "hydrogen fog" until the hydrogen was reionized (back to the state assumed before the CMBR was released, which was another reason photons from then aren't visible to us here and now). Yes, the universe is thought to have expanded greatly between the times the CMBR was released and the times that the stars reionized the hydrogen. But, realistically, what photons of what wavelengths should be visible to us now here on Earth from the processes that were occurring between the formation of hydrogen atoms and the formation of stars to reionize those hydrogen atoms? That is what we really want to be able to "see" with out telescopes, which will need to be able to see a very wide range of electromagnetic wave frequencies to cover that period of time, when the wavelengths were stretched by a factor up to than 1,100 between the time of emission and the time we are trying to observe them now. Reply
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How to experience life on the International Space Station

WHAT YOU NEED TO KNOW:

• Run time is approximately 45 minutes (35 minutes of which are in VR).
• The experience is accessible to those who are 8 years of age or older.
• Tickets: $45 to $50 for adults, $35 to $40 for students, $25 to $30 for kids ages eight to 12.

A new, first-of-its-kind, virtual reality experience is blasting off this summer at the Kravis Center for the Performing Arts. It's a space odyssey where you explore a virtual 3D replica of the International Space Station (ISS). Space Explorers: THE INFINITE boldly connects you with 360-degree cameras, so you can see exactly what the astronauts experience. Last weekend, I invited my bestie's twins, Enza and Alexa, from Jupiter and headed to a preview of the immersive exhibit.

We grabbed from a conveyor belt our virtual reality headset called an Oculus, which gets its information from a floor with green dots laid out in a ballroom. Felix Lajeunesse, chief creative officer of Felix & Paul Studios, is the attraction's director.

"So, that is really a giant tracking floor," Lajeunesse said. "It is made for us to be able to identify precisely where people are inside of the space, so that you have a perfectly tracked and fluid experience as you explore the International Space Station."

I explained to him how disoriented I was when I first put on the headset.

"So you know, it's black, and I'd like having trouble keeping my balance, because I'm not quite used to it yet," I said. "Is that something that's common for people?"

Lajeunesse told me it takes a brief moment to adjust.

"A lot of people that come here have never done a virtual reality experience in their lives, and so the first time they put it on, they need to first start walking," he said. "Sometimes it's a big leap for people but after first step, second step, you feel completely comfortable."

How do you avoid bumping into each other?

For 30 minutes you look for orbs and activate them to get a 360 video experience.

"Every time you actually activate a luminous orb, you see a scene that was filmed in space," Lajeunesse said. "Every time that scene is finished, there's an object that appears and you can play with that object in microgravity."

There are 60 different orb experiences. It's sort of like a "Choose Your Own Adventure" book.

"It's exactly like that. You sort of walk around the International Space Station in any order you want, you go anywhere you want, and you discover those luminous orbs," Lajeunesse said. "You activate them and they reveal a 3D 360 cinematic VR scene that was filmed in space on board the real space station by the crew."

"You and I will probably will never go to space. And so far, so little people went really to space. So, I think this experience is really the closest you'll get to ever go into space," added Myriam Achard, chief of new media partnerships and PR at PHI. "Maybe the future generations will. There will be more people going go into space."

All the astronauts who worked on the project have experienced the virtual reality experience.

What is the overview effect?

"To be in this experience to have the sense of presence of being fully immersed in that environment makes them feel like they're going back to where they live," Lajeunesse said. "So, it's a pretty profound emotional experience for them."

"But this experience, recreates really, you know, some astronaut that came to the infinite in Montreal or in Houston," Achard said. "When they removed the VR headset, some of them were crying, because they said you draw us back. I said, goosebumps so I think what we were able to create is really like is incredible."

When you first come into the experience, you see these displays with astronauts that served on the ISS during the project.

"Those are the crew members, the astronauts that participated to the creation of the experience both as protagonist and as the onboard production crew, because they were on space and we were on the ground," Lajeunesse said.

The experience lasts 30 minutes then you make your way into a chair with your headset on. I was uncertain on how to sit but I eventually did it and felt "safe."

What does a hurricane look like from space?

"And then once you're safe sitting in your chair, we show you the finale of the show, which is a spacewalk, the first ever spacewalk that was filmed in cinematic virtual reality with two astronauts in the vacuum of space, as they were doing a repair missions on the outside of the ISS," Lajeunesse said.

"We've never seen something like that. We've never experienced something like that," Achard said.

As for the twins, Enza and Alexa, what did they think?

"It was fun!," they said in unison.

"I liked how it looked like we were in space," Enza said.

Space Explorers at the Kravis Center

What do you want me to Shine A Light on? What are you most proud of where you live? Email me at [email protected] .

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