faster than light speed travel

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

Associate Professor of Physics, Oklahoma State University

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Mario Borunda does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

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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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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.

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Can anything travel faster than the speed of light?

Does it matter if it's in a vacuum?

In 1676, by studying the motion of Jupiter's moon Io, Danish astronomer Ole Rømer calculated that light travels at a finite speed. Two years later, building on data gathered by Rømer, Dutch mathematician and scientist Christiaan Huygens became the first person to attempt to determine the actual speed of light, according to the American Museum of Natural History in New York City. Huygens came up with a figure of 131,000 miles per second (211,000 kilometers per second), a number that isn't accurate by today's standards — we now know that the speed of light in the "vacuum" of empty space is about 186,282 miles per second (299,792 km per second) — but his assessment showcased that light travels at an incredible speed.

According to Albert Einstein 's theory of special relativity , light travels so fast that, in a vacuum, nothing in the universe is capable of moving faster. 

"We cannot move through the vacuum of space faster than the speed of light," confirmed Jason Cassibry, an associate professor of aerospace engineering at the Propulsion Research Center, University of Alabama in Huntsville.

Question answered, right? Maybe not. When light is not in a vacuum, does the rule still apply?

Related: How many atoms are in the observable universe?

"Technically, the statement 'nothing can travel faster than the speed of light' isn't quite correct by itself," at least in a non-vacuum setting, Claudia de Rham, a theoretical physicist at Imperial College London, told Live Science in an email. But there are certain caveats to consider, she said. Light exhibits both particle-like and wave-like characteristics, and can therefore be regarded as both a particle (a photon ) and a wave. This is known as wave-particle duality.

If we look at light as a wave, then there are "multiple reasons" why certain waves can travel faster than white (or colorless) light in a medium, de Rham said. One such reason, she said, is that "as light travels through a medium — for instance, glass or water droplets — the different frequencies or colors of light travel at different speeds." The most obvious visual example of this occurs in rainbows, which typically have the long, faster red wavelengths at the top and the short, slower violet wavelengths at the bottom, according to a post by the University of Wisconsin-Madison . 

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When light travels through a vacuum, however, the same is not true. "All light is a type of electromagnetic wave, and they all have the same speed in a vacuum (3 x 10^8 meters per second). This means both radio waves and gamma rays have the same speed," Rhett Allain, a physics professor at Southeastern Louisiana University, told Live Science in an email.

So, according to de Rham, the only thing capable of traveling faster than the speed of light is, somewhat paradoxically, light itself, though only when not in the vacuum of space. Of note, regardless of the medium, light will never exceed its maximum speed of 186,282 miles per second.

Universal look

According to Cassibry, however, there is something else to consider when discussing things moving faster than the speed of light.

"There are parts of the universe that are expanding away from us faster than the speed of light, because space-time is expanding," he said. For example, the Hubble Space Telescope recently spotted 12.9 billion year-old light from a distant star known as Earendel. But, because the universe is expanding at every point, Earendel is moving away from Earth and has been since its formation, so the galaxy is now 28 billion light years away from Earth.

In this case, space-time is expanding, but the material in space-time is still traveling within the bounds of light speed.

Related: Why is space a vacuum?

So, it's clear that nothing travels faster than light that we know of, but is there any situation where it might be possible? Einstein's theory of special relativity, and his subsequent theory of general relativity, is "built under the principle that the notions of space and time are relative," de Rham said. But what does this mean? "If someone [were] able to travel faster than light and carry information with them, their notion of time would be twisted as compared to ours," de Rham said. "There could be situations where the future could affect our past, and then the whole structure of reality would stop making sense."

This would indicate that it would probably not be desirable to make a human travel faster than the speed of light. But could it ever be possible? Will there ever be a time when we are capable of creating craft that could propel materials — and ultimately humans — through space at a pace that outstrips light speed? "Theorists have proposed various types of warp bubbles that could enable faster-than-light travel," Cassibry said.

But is de Rham convinced?

"We can imagine being able to communicate at the speed of light with systems outside our solar system ," de Rham said. "But sending actual physical humans at the speed of light is simply impossible, because we cannot accelerate ourselves to such speed.

"Even in a very idealistic situation where we imagine we could keep accelerating ourselves at a constant rate — ignoring how we could even reach a technology that could keep accelerating us continuously — we would never actually reach the speed of light," she added. "We could get close, but never quite reach it."

Related: How long is a galactic year?

This is a point confirmed by Cassibry. "Neglecting relativity, if you were to accelerate with a rate of 1G [Earth gravity], it would take you a year to reach the speed of light. However, you would never really reach that velocity because as you start to approach lightspeed, your mass energy increases, approaching infinite. "One of the few known possible 'cheat codes' for this limitation is to expand and contract spacetime, thereby pulling your destination closer to you. There seems to be no fundamental limit on the rate at which spacetime can expand or contract, meaning we might be able to get around this velocity limit someday."

— What would happen if the speed of light were much lower?

— What if the speed of sound were as fast as the speed of light?

— How does the rubber pencil illusion work?

Allain is similarly confident that going faster than light is far from likely, but, like Cassibry, noted that if humans want to explore distant planets, it may not actually be necessary to reach such speeds. "The only way we could understand going faster than light would be to use some type of wormhole in space," Allain said. "This wouldn't actually make us go faster than light, but instead give us a shortcut to some other location in space."

Cassibry, however, is unsure if wormholes will ever be a realistic option.

"Wormholes are theorized to be possible based on a special solution to Einstein's field equations," he said. "Basically, wormholes, if possible, would give you a shortcut from one destination to another. I have no idea if it's possible to construct one, or how we would even go about doing it." Originally published on Live Science.

Joe Phelan is a journalist based in London. His work has appeared in VICE, National Geographic, World Soccer and The Blizzard, and has been a guest on Times Radio. He is drawn to the weird, wonderful and under examined, as well as anything related to life in the Arctic Circle. He holds a bachelor's degree in journalism from the University of Chester. 

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March 9, 2021

Breaking the warp barrier for faster-than-light travel

by University of Göttingen

If travel to distant stars within an individual's lifetime is going to be possible, a means of faster-than-light propulsion will have to be found. To date, even recent research about superluminal (faster-than-light) transport based on Einstein's theory of general relativity would require vast amounts of hypothetical particles and states of matter that have 'exotic' physical properties such as negative energy density. This type of matter either cannot currently be found or cannot be manufactured in viable quantities. In contrast, new research carried out at the University of Göttingen gets around this problem by constructing a new class of hyper-fast 'solitons' using sources with only positive energies that can enable travel at any speed. This reignites debate about the possibility of faster-than-light travel based on conventional physics. The research is published in the journal Classical and Quantum Gravity .

The author of the paper, Dr. Erik Lentz, analyzed existing research and discovered gaps in previous 'warp drive' studies. Lentz noticed that there existed yet-to-be explored configurations of space-time curvature organized into 'solitons' that have the potential to solve the puzzle while being physically viable. A soliton—in this context also informally referred to as a 'warp bubble'—is a compact wave that maintains its shape and moves at constant velocity. Lentz derived the Einstein equations for unexplored soliton configurations (where the space-time metric's shift vector components obey a hyperbolic relation), finding that the altered space-time geometries could be formed in a way that worked even with conventional energy sources. In essence, the new method uses the very structure of space and time arranged in a soliton to provide a solution to faster-than-light travel , which—unlike other research—would only need sources with positive energy densities. No exotic negative energy densities needed.

If sufficient energy could be generated, the equations used in this research would allow space travel to Proxima Centauri, our nearest star, and back to Earth in years instead of decades or millennia. That means an individual could travel there and back within their lifetime. In comparison, the current rocket technology would take more than 50,000 years for a one-way journey. In addition, the solitons (warp bubbles) were configured to contain a region with minimal tidal forces such that the passing of time inside the soliton matches the time outside: an ideal environment for a spacecraft. This means there would not be the complications of the so-called 'twin paradox' whereby one twin traveling near the speed of light would age much more slowly than the other twin who stayed on Earth: in fact, according to the recent equations both twins would be the same age when reunited.

"This work has moved the problem of faster-than-light travel one step away from theoretical research in fundamental physics and closer to engineering. The next step is to figure out how to bring down the astronomical amount of energy needed to within the range of today's technologies, such as a large modern nuclear fission power plant. Then we can talk about building the first prototypes," says Lentz.

Currently, the amount of energy required for this new type of space propulsion drive is still immense. Lentz explains, "The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter. The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors." He goes on to say: "Fortunately, several energy-saving mechanisms have been proposed in earlier research that can potentially lower the energy required by nearly 60 orders of magnitude." Lentz is currently in the early-stages of determining if these methods can be modified, or if new mechanisms are needed to bring the energy required down to what is currently possible.

Provided by University of Göttingen

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Scientists Believe Light Speed Travel Is Possible. Here’s How.

A functioning warp drive would allow humans to reach the far ends of the cosmos in the blink of an eye.

White and his team in LSI’s Houston laboratory were conducting research for the Defense Advanced Research Projects Agency, or DARPA, and had set up these particular experiments to study the energy densities within Casimir cavities, the mysterious spaces between microscopic metal plates in a vacuum. The data plot indicated areas of diminished energy between the plates, which caused them to push toward each other as if trying to fill the void. This is known as negative vacuum energy density, a phenomenon in quantum mechanics called, appropriately enough, the Casimir effect . It’s something that’s helping scientists understand the soupy physics of microscale structures, which some researchers hope can be applied to energy applications that are more practical, such as circuits and electromechanical systems.

But White noticed that the pattern of negative vacuum energy between the plates and around tiny cylindrical columns that they’d inserted in the space looked familiar. It precisely echoed the energy pattern generated by a type of exotic matter that some physicists believe could unlock high-speed interstellar travel. “We then looked, mathematically, at what happens if we placed a one-micron sphere inside of a four-micron cylinder under the same conditions, and found that this kind of structure could generate a little nanoscale warp bubble encapsulating that central region,” White explains.

That’s right—a warp bubble. The essential component of a heretofore fictional warp drive that has for decades been the obsession of physicists, engineers, and sci-fi fans. Warp drive, of course, is the stuff of Star Trek legend, a device enclosed within a spacecraft that gives the mortals aboard the ability to rip around the cosmos at superhuman speed. To the lay sci-fi fan, it’s a “black box”—a convenient, completely made-up workaround to avoid the harsh realities of interstellar travel. However, after decades of speculation, research, and experimentation, scientists believe a warp drive could actually work.

To emphasize: White didn’t actually make a warp bubble. But the data from his study led to an aha moment: For the first time, a buildable warp bubble showed promise of success.

Warp technology’s core science is surprisingly sound. Though the specific mechanics of an actual device haven’t been fully unpacked, the math points toward feasibility. In short, a real-life warp drive would use massive amounts of energy, which can come in the form of mass, to create enough gravitational pull to distort spacetime in a controlled fashion, allowing a ship to speed along inside a self-generated bubble that itself is able to travel at essentially any speed. Warp drives popped up in fiction intermittently for several decades before Star Trek creator Gene Roddenberry plugged one into the USS Enterprise in 1966. But Miguel Alcubierre, PhD, a Mexican theoretical physicist and professed Star Trek enthusiast, gave the idea real-world legs when he released a paper in 1994 speculating that such a drive was mathematically possible. It was the first serious treatment of a warp drive’s feasibility, and it made headlines around the world. His breakthrough inspired more scientists to nudge the theoretical aspects of warp drive toward concrete, practical applications.

“I proposed a ‘geometry’ for space that would allow faster-than-light travel as seen from far away, essentially expanding space behind the object we want to move and contracting it in front,” Alcubierre says. “This forms a ‘bubble’ of distorted space, inside of which an object—a spaceship, say—could reside.”

Physicists tend to speak in relative terms. By injecting the sly qualifier “as seen from far away,” Alcubierre might sound like he’s describing the galactic equivalent of an optical illusion —an effect perhaps similar to driving past a truck going the opposite direction on the highway when you’re both going 60 miles an hour. Sure feels like a buck-twenty, doesn’t it? But the A-to-B speed is real; the warp effect simply shortens the literal distance between two points. You’re not, strictly speaking, moving faster than light. Inside the bubble, all appears relatively normal, and light moves faster than you are, as it should. Outside the bubble, however, you’re haulin’ the mail.

.css-2l0eat{font-family:UnitedSans,UnitedSans-roboto,UnitedSans-local,Helvetica,Arial,Sans-serif;font-size:1.625rem;line-height:1.2;margin:0rem;padding:0.9rem 1rem 1rem;}@media(max-width: 48rem){.css-2l0eat{font-size:1.75rem;line-height:1;}}@media(min-width: 48rem){.css-2l0eat{font-size:1.875rem;line-height:1;}}@media(min-width: 64rem){.css-2l0eat{font-size:2.25rem;line-height:1;}}.css-2l0eat b,.css-2l0eat strong{font-family:inherit;font-weight:bold;}.css-2l0eat em,.css-2l0eat i{font-style:italic;font-family:inherit;} THOUGH THE SPECIFIC MECHANICS OF AN ACTUAL DEVICE HAVEN’T BEEN UNPACKED, THE MATH POINTS TOWARD FEASIBILITY.

Alcubierre’s proposal had solved one of the initial hurdles to achieving warp speeds: The very idea clashes with Einstein’s long-accepted theory of general relativity, which states that nothing can travel faster than the speed of light, but it doesn’t preclude space itself from traveling faster than that. In fact, scientists speculate that the same principles explain the rapid expansion of the universe after the Big Bang .

While concluding that warp speed was indeed possible, Alcubierre also found that it would require an enormous amount of energy to sustain the warp bubble. He theorized that negative energy—the stuff hinted at by White’s experimentation with Casimir cavities—could be a solution. The only problem is that no one has yet proved that negative energy is real. It’s the unobtanium of our spacefaring imaginations, something researchers only believe to exist. In theory, however, this unknown matter may be sufficiently powerful that future warp drive designers could channel it to contract spacetime around it. In conceptual drawings of warp-capable spacecraft , enormous material rings containing this energy source surround a central fuselage. When activated, it warps spacetime around the entire ship. The more intense the warping, the faster the warp travel is achieved.

Of course, it’s not that simple. Physicist José Natário, PhD, a professor at the Instituto Superior Técnico in Lisbon, wrote his own influential paper about the mathematical feasibility of warp drives in 2001. However, he is concerned about practical conundrums, like the amount of energy required. “You need to be able to curve spacetime quite a lot in order to do this,” he says. “We’re talking about something that would be much, much more powerful than the sun.”

Alcubierre is similarly skeptical that his theoretical ideas might ever be used to develop a working warp drive. “In order to have a bubble about 100 meters wide traveling at precisely the speed of light, you would need about 100 times the mass of the planet Jupiter converted into negative energy, which of course sounds absurd,” he says. By that standard, he concludes, a warp drive is very unlikely.

Physicists love a challenge, though. In the 29 years since Alcubierre published his paper, other scientists have wrestled with the implications of the work, providing alternative approaches to generating the energy using more accessible power sources, finding oblique entry points to the problem, and batting ideas back and forth in response to one another’s papers. They use analogies involving trampolines , tablecloths, bowling balls, balloons, conveyor belts, and music to explain the physics.

They even have their own vocabulary. It’s not faster-than-light travel; it’s superluminal travel, thank you. Then there’s nonphysical and physical—a.k.a. the critical distinction between theoretical speculation and something that can actually be engineered. (Pro tip: We’re aiming for physical here, folks.) They do mention Star Trek a lot, but never Star Wars . Even the scruffiest-looking nerf herder knows that the ships in Star Wars use hyperdrive, which consumes fuel, rather than warp drives, which don’t use propulsive technology but instead rely on, well, warping. They’re also vague about details like what passengers would experience, what gravity is like on board since you’re carrying around boatloads of energy, and what would happen if someone, say, jumped out of the ship while warping. (A speculative guess: Nothing good.)

Such research isn’t typically funded by academic institutions or the DARPAs and NASAs of the world, so much of this work occurs in the scientists’ spare time. One such scientist and Star Trek enthusiast is physicist Erik Lentz, PhD. Now a researcher at Pacific Northwest National Laboratory in Richland, Washington, Lentz was doing postdoctoral work at Göttingen University in Germany when, amid the early, isolated days of the pandemic, he mulled the idea of faster-than-light travel. He published a paper in 2021 arguing that warp drives could be generated using positive energy sources instead of the negative energy that Alcubierre’s warp drive seemed to require.

“There are a number of barriers to entry to actually being able to build a warp drive,” Lentz says. “The negative energy was the most obvious, so I tried to break that barrier down.”

He explored a new class of solutions in Einstein’s general relativity while focusing on something called the weak-energy condition, which, he explains, tracks the positivity of energy in spacetime. He hit upon a “soliton solution”—a wave that maintains its shape and moves at a constant velocity—that could both satisfy the energy-level challenge and travel faster than light. Such a warp bubble could travel along using known energy sources, though harnessing those at the levels needed are still far beyond our capabilities. The next step, he notes, may be bringing the energy requirements for a warp drive to within the range of a nuclear fusion reactor.

A fusion-powered device could theoretically travel to and from Proxima Centauri , Earth’s nearest star, in years instead of decades or millennia, and then go faster and faster as power sources improve. Current conventional rocket technology, on the other hand, would take 50,000 years just for a one-way trip—assuming, of course, there was an unlimited fuel supply for those engines.

“IF YOU COLLIDE WITH SOMETHING ON YOUR PATH, IT WOULD ALMOST CERTAINLY BE CATASTROPHIC.”

Like Alcubierre’s original thesis, Lentz’s paper had a seismic impact on the warp drive community, prompting yet another group of scientists to dig into the challenge. Physicist Alexey Bobrick and technology entrepreneur Gianni Martire have been particularly prolific. In 2021, they released a paper theorizing that a class of subliminal warp drives, traveling at just a fraction of light speed, could be developed from current scientific understanding. While that paper essentially argued that it’s perfectly acceptable to walk before you can run, they followed it up with another theory earlier this year that describes how a simulated black hole , created using sound waves and glycerin and tested with a laser beam, could be used to evaluate the levels of gravitational force needed to warp spacetime. The duo coded that breakthrough into a public app that they hope will help more quickly push theoretical ideas to practical ones. Though the team is waiting for the technology to clear a peer review stage before releasing details, the app is essentially a simulator that allows scientists to enter their warp-speed equations to validate whether they’re practical.

“When somebody publishes a warp metric for the first time, people say, ‘Okay, is your metric physical?’” Martire says. The answer to that question—whether the metric has practical potential or is strictly theoretical—is hard to establish given the challenges of testing these hypotheses. That determination could take six to eight months. “Now we can tell you within seconds, and it shows you visually how off you are or how close you are,” he says.

While useful, the app will speed up the preliminary math only for future researchers. Galaxy-sized challenges remain before we ever experience turbocharged interstellar travel. Alcubierre worries in particular about what may happen near the walls of the warp bubble. The distortion of space is so violent there, he notes, that it would destroy anything that gets close. “If you collide with something on your path, it would almost certainly be catastrophic,” he says.

Natário mulls even more practical issues, like steering and stopping. “It’s a bubble of space, that you’re pushing through space,” he says. “So, you’d have to tell space ... to curve in front of your spaceship.” But therein lies the problem: You can’t signal to the space in front of you to behave the way you want it to.

His opinion? Superluminal travel is impossible. “You need these huge deformations that we have no idea how to accomplish,” Natário says. “So yes, there has been a lot of effort toward this and studying these weird solutions, but this is all still completely theoretical, abstract, and very, very, very, very far from getting anywhere near a practical warp drive.” That’s “very” to the power of four, mind you—each crushing blow pushing us exponentially, excruciatingly further and further away from our yearned-for superluminal lives.

Ultimately, the pursuit of viable high-speed interstellar transportation also points to a more pressing terrestrial challenge: how the scientific community tackles ultra-long-term challenges in the first place. Most of the research so far has come from self-starters without direct funding, or by serendipitous discoveries made while exploring often unrelated research, such as Dr. White’s work on Casimir cavities.

Many scientists argue that we’re in a multi-decade period of stagnation in physics research, and warp drive—despite its epic time horizons before initial research leads to galaxy-spanning adventures—is somewhat emblematic of that stagnation. Sabine Hossenfelder, a research fellow at the Frankfurt Institute for Advanced Studies and creator of the YouTube channel Science Without the Gobbledygook , noted in a 2020 blog post that physics research has drifted away from frequent, persistent physical experimentation to exorbitant infusions of cash into relatively few devices. She writes that with fewer experiments, serendipitous discoveries become increasingly unlikely. Without those discoveries, the technological progress needed to keep experiments economically viable never materializes.

When asked whether this applied equally to warp drive, Hossenfelder sees a faint but plausible connection. “Warp drives are an idea that is not going to lead to applications in the next 1,000 years or so,” she says. “So they don’t play a big role in that one way to another. But when it comes to the funding, you see some overlap in the problems.”

So, despite all the advances, the horizon for a warp drive remains achingly remote. That hasn’t fazed the scientists involved, though. A few years ago, while teaching in France, White visited the Strasbourg Cathedral with his wife. While admiring its 466-foot-tall spire, he was struck by the fact that construction began in 1015 but didn’t wrap up until 1439—a span of 424 years. Those who built the basement had no chance of ever seeing the finished product, but they knew they had to do their part to aid future generations. “I don’t have a crystal ball,” White says. “I don’t know what the future holds. But I know what I need to be doing right now.”

Eric Adams is a writer and photographer who focuses on technology, transportation, science, travel, and other subjects for a wide range of outlets, including Wired, The Drive, Gear Patrol, Men's Health, Popular Science, Forbes, and others.

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Tachyons: Facts about these faster-than-light particles

Tachyons are not just the stuff of science fiction.

What is a tachyon?

Tachyons and time travel, tachyons paradoxes, tachyons. could we ever detect them, the power of imagination in science, additional information.

Traveling faster than light and time-travel could be real for tachyons. If one thing science fiction excels at, it's allowing us to marvel at the breaking of the physical laws of the universe. We watch and read in wonder as the warp engines of the starship Enterprise push it to beyond the speed of light, or as Barry or Wally  —  whoever is carrying the name of the Flash at the time  —  does the same in no more than a pair of yellow boots. 

Likewise, we enjoy tales of adventurers like the Doctor, or Doc Brown, using weird seemingly antiquated machinery to violate the laws of causality. What if there was a fundamental particle that could do all these things? Moving faster than light like the Flash, and traveling back through time without the need for a TARDIS or a Delorian or yellow boots. 

That’s a tachyon. But make no mistake, these particles aren’t just the idling's of science fiction writers. Tachyons are the stuff of "hard" science. 

Related: What would happen if the speed of light was much lower?  

Tachyons are one of the most interesting elements arising from Einstein’s theory of special relativity . The 1905 theory is based on two postulates, nothing with mass moves faster than the speed of light ( c ), and physical laws remain the same in all non-inertial reference frames. A significant consequence of special relativity is the fact that space and time are united into a single entity; spacetime. That mean’s a particle’s journey through speed is linked to its journey through time. 

The term "tachyon" first entered scientific literature in 1967, in a paper entitled " Possibility of faster-than-light particles " by Columbia University physicist Gerald Feinberg. Feinberg posited that tachyonic particles would arise from a quantum field with “imaginary mass” explaining why the first populate of special relativity doesn’t restrain their velocity.

This would lead to two types of particles existing in the universe ; bradyons that travel slower than light and compose all the matter we see around us, and tachyons traveling faster than light, according to the University of Pittsburgh . One of the key differences between these particle types is as energy is added to bradyons, they speed up. But, with tachyons, as energy is taken away, their speed increases. 

One of the most important and meaningful results from Einstein’s theory of special relativity is the establishing universal speed limit of c ; the speed of light in a vacuum. 

Einstein suggested that as an object approaches c its mass becomes near-infinite, as does the energy required to accelerate it. This should mean that nothing can travel faster than light. But, imagine an anti-mass particle like a tachyon, its lowest energy state would see it speeding at c . But, why would this lead to backward time travel?

That all hinges on the concept that puts the "relative" into "special relativity."

A common tool used to explain special relativity is the spacetime diagram. 

Spacetime is filled with events ranging from the cosmically powerful and violent, like the supernova explosion of a distant star, or the mundane, such as the cracking of an egg on your kitchen floor. And these are mapped onto the spacetime diagram. This diagram shows as a particle whizzes through spacetime, it traces out a worldline that maps its progress.

Also filling spacetime are observers, each of whom has their own reference frame. These observers may see the events that fill spacetime occurring in different orders. Observer 1 may see event A, the supernova, occur before event B the egg crack. Observer 2 however may see event B happening before event A. 

Each event has a light cone associated with it. If event B falls within the lightcone of event A then the two could be causally linked. The supernova could have knocked the egg off the kitchen counter  —  or maybe the falling breakfast item caused the complete gravitational collapse of a dying star, somehow. That’s because in the light cone a signal traveling slower than light can link the events. The edges of the light cone represent the speed of light. Linking an event outside the light cone with one inside it requires a signal that travels faster than light.

If event A is in the light cone and event B is outside it, then the supernova and egg-related tragedy can't be causally related. But, a tachyon traveling at a speed greater than the speed of light could violate causality by linking these events. 

To see why this is a problem, consider it like this. Image event A is the sending of a signal, and event B is the receiving of that signal. If that signal is traveling at the speed of light, or slower all observers in different reference frames agree that A preceded B.

But, if that signal is carried by a tachyon and thus moves faster than light, there will be reference frames that say the signal was received before it was sent. Thus, to an observer in this frame, the tachyon traveled backward in time.

One of the fundamental postulates of special relativity is that the laws of physics should be the same in all non-accelerating reference frames. That means if tachyons can violate causality and move backward in time in one reference frame, it can do it in them all.  

To see how this leads to problems called paradoxes, consider two observers, Stella aboard a spacecraft orbiting Earth, and Terra based on the surface of the planet. The two are communicating by sending messages with tachyons. 

This means that if Stella sends a signal to Terra which moves faster than light in Stella’s frame but backward in time in Terra’s frame. Terra then sends a reply as ordered which moves faster than light in her frame but backward in time in Stella’s frame, Stella could receive the reply before sending the original signal. 

What if this response signal from Terra says "do not send any signals"? Then Stella does not send the original signal, and Terra then has nothing to respond to and never sends the tachyon signal that says "don’t send any signals." 

So not only do tachyons violate causality in every frame they open the door to severe logical paradoxes.

There are suggestions as to how these paradoxes could be avoided. Of course, the most simple solution is that tachyons don’t exist. 

A less draconian suggestion is that observers in different reference frames can’t tell the difference between the emission and absorption of tachyons. 

That means a tachyon traveling back in time could always be interpreted as a tachyon moving forward in time because receiving a tachyon from the future always creates the same tachyon and sends it forwards in time.

Another suggestion is that tachyons aren’t like any other particle we know of, in that they don't interact and can never be detected or observed. Meaning that the tachyon communication system used by Stella and Terra in the above example can’t exist. 

Along similar lines, other researchers say that tachyons can’t be controlled. The receipt and emission of tachyons just happen at random. Thus, there’s no way to send a tachyon with a causality violating message. 

Aside from the fact that like other particles, they are likely incomprehensibly tiny, because tachyons always travel faster than light it isn’t possible to detect one on its approach. That’s because it’s moving faster than any associated photons. 

After it passes, an observer would see the image of the tachyon split into two distinct images. These would show it simultaneously arriving in one direction and disappearing in the opposite direction.

If detecting tachyons, at least of their approach, with light is out of the picture, is there another way we could detect these faster than light particles?

Possibly. Tachyons are proposed to have an "anti-mass" but this still constitutes mass energy. That means these particles should still have some gravitational effect. It’s possible highly sensitive detectors could spot this effect.

An alternative detection method could arise from their faster-than-light nature.

While the speed of light in a vacuum c is a universal speed limit, particles have been made to travel faster than light in other mediums. When electrically charged particles are accelerated up to and beyond the speed of light in certain mediums like water, they release a form of radiation called Cherenkov radiation, according to the International Atomic Energy Agency .

That means that if tachyons are electrically charged, one way of detecting them would be measuring Cherenkov radiation in the near-vacuum of space. 

What tachyons really demonstrate is the importance of imagination in our ongoing quest to understand the universe. They may not exist, and if they do we may have no hope of ever measuring one.

But what our technology can’t capture, our minds can. We can consider the possibility of a particle that journeys back through time and what that says about the nature of time, and the Universe, and the events that fill them.

In an interview with George Sylvester Viereck published in " The Saturday Evening Post " in 1929, Albert Einstein is believed to have said: "Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world."

•  Discover more about Tachyons with this informative YouTube video . 
•  Explore the possible experimental evidence for the existence of tachyons with George Mason University .  
•  Find out how Cherenkov radiation works with this video from Fermi Lab .  

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Robert Lea is a science journalist in the U.K. whose articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space, Newsweek and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University. Follow him on Twitter @sciencef1rst.

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Three ways to travel at (nearly) the speed of light.

Katy Mersmann

1) electromagnetic fields, 2) magnetic explosions, 3) wave-particle interactions.

One hundred years ago today, on May 29, 1919, measurements of a solar eclipse offered verification 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.

One of NASA’s jobs is to better understand how these particles are accelerated. Studying these superfast, or relativistic, particles can ultimately help protect missions exploring the solar system, traveling to the Moon, and they can teach us more about our galactic neighborhood: A well-aimed near-light-speed particle can trip onboard electronics and too many at once could have negative radiation effects on space-faring astronauts as they travel to the Moon — or beyond.

Here are three ways that acceleration happens.

Most of the processes that accelerate particles to relativistic speeds work with electromagnetic fields — the same force that keeps magnets on your fridge. The two components, electric and magnetic fields, like two sides of the same coin, work together to whisk particles at relativistic speeds throughout the universe.

In essence, electromagnetic fields accelerate charged particles because the particles feel a force in an electromagnetic field that pushes them along, similar to how gravity pulls at objects with mass. In the right conditions, electromagnetic fields can accelerate particles at near-light-speed.

On Earth, electric fields are often specifically harnessed on smaller scales to speed up particles in laboratories. Particle accelerators, like the Large Hadron Collider and Fermilab, use pulsed electromagnetic fields to accelerate charged particles up to 99.99999896% the speed of light. At these speeds, the particles can be smashed together to produce collisions with immense amounts of energy. This allows scientists to look for elementary particles and understand what the universe was like in the very first fractions of a second after the Big Bang. 

Download related video from NASA Goddard’s Scientific Visualization Studio

Magnetic fields are everywhere in space, encircling Earth and spanning the solar system. They even guide charged particles moving through space, which spiral around the fields.

When these magnetic fields run into each other, they can become tangled. When the tension between the crossed lines becomes too great, the lines explosively snap and realign in a process known as magnetic reconnection. The rapid change in a region’s magnetic field creates electric fields, which causes all the attendant charged particles to be flung away at high speeds. Scientists suspect magnetic reconnection is one way that particles — for example, the solar wind, which is the constant stream of charged particles from the Sun — is accelerated to relativistic speeds.

Those speedy particles also create a variety of side-effects near planets.  Magnetic reconnection occurs close to us at points where the Sun’s magnetic field pushes against Earth’s magnetosphere — its protective magnetic environment. When magnetic reconnection occurs on the side of Earth facing away from the Sun, the particles can be hurled into Earth’s upper atmosphere where they spark the auroras. Magnetic reconnection is also thought to be responsible around other planets like Jupiter and Saturn, though in slightly different ways.

NASA’s Magnetospheric Multiscale spacecraft were designed and built to focus on understanding all aspects of magnetic reconnection. Using four identical spacecraft, the mission flies around Earth to catch magnetic reconnection in action. The results of the analyzed data can help scientists understand particle acceleration at relativistic speeds around Earth and across the universe.

Particles can be accelerated by interactions with electromagnetic waves, called wave-particle interactions. When electromagnetic waves collide, their fields can become compressed. Charged particles bouncing back and forth between the waves can gain energy similar to a ball bouncing between two merging walls.

These types of interactions are constantly occurring in near-Earth space and are responsible for accelerating particles to speeds that can damage electronics on spacecraft and satellites in space. NASA missions, like the Van Allen Probes , help scientists understand wave-particle interactions.

Wave-particle interactions are also thought to be responsible for accelerating some cosmic rays that originate outside our solar system. After a supernova explosion, a hot, dense shell of compressed gas called a blast wave is ejected away from the stellar core. Filled with magnetic fields and charged particles, wave-particle interactions in these bubbles can launch high-energy cosmic rays at 99.6% the speed of light. Wave-particle interactions may also be partially responsible for accelerating the solar wind and cosmic rays from the Sun.

Download this and related videos in HD formats from NASA Goddard’s Scientific Visualization Studio

By Mara Johnson-Groh NASA’s Goddard Space Flight Center , Greenbelt, Md.

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What If You Traveled Faster Than the Speed of Light?

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When we were kids, we were amazed that Superman could travel "faster than a speeding bullet." We could even picture him, chasing down a projectile fired from a weapon, his right arm outstretched, his cape rippling behind him. If he traveled at half the bullet 's speed, the rate at which the bullet moved away from him would halve. If he did indeed travel faster than the bullet, he would overtake it and lead the way. Go, Superman!

In other words, Superman's aerial antics obeyed Newton's views of space and time : that the positions and motions of objects in space should all be measurable relative to an absolute, nonmoving frame of reference [source: Rynasiewicz ].

In the early 1900s, scientists held firm to the Newtonian view of the world. Then a German-born mathematician and physicist by the name of Albert Einstein came along and changed everything. In 1905, Einstein published his theory of special relativity , which put forth a startling idea: There is no preferred frame of reference. Everything, even time, is relative.

Two important principles underpinned his theory. The first stated that the same laws of physics apply equally in all constantly moving frames of reference. The second said that the speed of light — about 186,000 miles per second (300,000 kilometers per second) — is constant and independent of the observer's motion or the source of light. According to Einstein, if Superman were to chase a light beam at half the speed of light, the beam would continue to move away from him at exactly the same speed [source: Stein , AMNH.org ].

These concepts seem deceptively simple, but they have some mind-bending implications. One of the biggest is represented by Einstein's famous equation, E = mc², where E is energy, m is mass and c is the speed of light.

According to this equation, mass and energy are the same physical entity and can be changed into each other. Because of this equivalence, the energy an object has due to its motion will increase its mass. In other words, the faster an object moves, the greater its mass. This only becomes noticeable when an object moves really quickly. If it moves at 10 percent the speed of light, for example, its mass will only be 0.5 percent more than normal. But if it moves at 90 percent the speed of light, its mass will double [source: LBL.gov ].

As an object approaches the speed of light, its mass rises precipitously. If an object tries to travel 186,000 miles per second, its mass becomes infinite, and so does the energy required to move it. For this reason, no normal object can travel as fast or faster than the speed of light.

That answers our question, but let's have a little fun and modify the question slightly.

Almost As Fast As the Speed of Light?

We covered the original question, but what if we tweaked it to say, "What if you traveled almost as fast as the speed of light?" In that case, you would experience some interesting effects. One famous result is something physicists call time dilation , which describes how time runs more slowly for objects moving very rapidly. If you flew on a rocket traveling 90 percent of light-speed, the passage of time for you would be halved. Your watch would advance only 10 minutes, while more than 20 minutes would pass for an Earthbound observer [source: May ]

You would also experience some strange visual consequences. One such consequence is called aberration , and it refers to how your entire field of view would shrink down to a tiny, tunnel-shaped "window" out in front of your spacecraft. This happens because photons (those exceedingly tiny packets of light) — even photons behind you — appear to come in from the forward direction.

In addition, you would notice an extreme Doppler effect , which would cause light waves from stars in front of you to crowd together, making the objects appear blue. Light waves from stars behind you would spread apart and appear red. The faster you go, the more extreme this phenomenon becomes until all visible light from stars in front of the spacecraft and stars to the rear become completely shifted out of the known visible spectrum (the colors humans can see). When these stars move out of your perceptible wavelength, they simply appear to fade to black or vanish against the background.

Of course, if you want to travel faster than a speeding photon, you'll need more than the same rocket technology we've been using for decades.

In a March 2021 paper published in the journal Classical and Quantum Gravity , astrophysicist Erik Lentz of the University of Göttingen in Germany proposed the idea of rearranging space-time to create a warp bubble, inside which a spacecraft might be able to travel at faster-than-light speeds.

Speed of Light FAQ

Is there anything faster than the speed of light, how fast is the speed of light in miles, why is "c" the speed of light, what is the speed of light on earth, lots more information, related articles.

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• American Museum of Natural History. "A Matter of Time. " Amnh.org. (Feb. 16, 2022) https://www.amnh.org/exhibitions/einstein/time/a-matter-of-time
• Brandeker, Alexis. "What would a relativistic interstellar traveler see?" Usenet Physics FAQ. May 2002. (Feb. 16, 2022J) http://www.desy.de/user/projects/Physics/Relativity/SR/Spaceship/spaceship.html
• Carl Sagan's Cosmos. "Travels in Space and Time." YouTube. Video uploaded Nov. 27, 2006 (Feb. 16, 2022 ) https://www.youtube.com/watch?v=2t8hUaaZVJg
• Hawking, Stephen. "The Illustrated Brief History of Time. " Bantam. 1996. (Feb. 16. 2022) https://bit.ly/367UGpZ
• EurekAlert! "Breaking the warp barrier for faster-than-light travel. " Eurekalert.org. March 9, 2021. (Feb. 16, 2022) https://www.eurekalert.org/news-releases/642756
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Will Humans Ever Go Faster Than Light?

Why can't we travel faster than the speed of light find out what complications arise as physicists explore light speed..

Einstein’s special theory of relativity governs our understanding of both the flow of time and the speed at which objects can move. In special relativity, the speed of light is the ultimate speed limit to the universe. Nothing can travel faster than it. Every single moving object in the universe is constrained by that fundamental limit.

Speed of Light and Sound

This isn’t something like the speed of sound . Early scientists wondered if we could ever go faster than that speed, not because of some fundamental rule of the universe, but because we didn’t know if our engineering and materials science capabilities could withstand the extreme turbulence generated by moving at such speeds. But everyday objects already surpass the speed of sound. For example, the crack of a whip is caused by the tip creating a sonic boom as it travels faster than the sound speed.

Read More: Is There a Particle That Can Travel Back in Time?

The problem with trying to surpass the speed of light is that as you go faster, the more kinetic energy you have. But relativity tells us that energy is the same as mass, so the faster you go the more massive you become (and yes, this means that a moving baseball has more mass than one standing still, but that’s a tiny effect).

As you approach the speed of light, your mass balloons up to infinity. The closer you get to the speed of light, the more out of control your mass becomes. With higher masses, you must push yourself harder to accelerate, and you quickly find yourself in a position where it would take an infinite amount of energy to overcome light speed.

Exploring Light Speed

This isn’t just a matter of clever engineering or figuring out some trick – this is built into the fabric of the universe.

That said, there are proposals out there for designing specialized devices that could supposedly overcome this limit without outright breaking relativity. These concepts work because special relativity is a law of local physics: It tells you that you can never measure nearby motion going faster than light speed.

For example, a wormhole could send you to a distant destination faster than you could go traveling normally through space, even though you could travel down the wormhole as slowly as you want. The “ Alcubierre drive ” is essentially a warp drive, deforming spacetime near you so that it can pull you forward as fast as you want to go – even faster than light – without once even firing a rocket.

Read More: Black Holes Are Accelerating The Expansion Of The Universe, Say Cosmologists

Negative Mass and Backward Time Travel

But these fanciful ideas suffer from two drawbacks. For one, to function they each require the use of some exotic form of matter, namely matter that has negative mass . Negative mass is truly weird. If you were to drop a ball of negative mass, it would fly up. If you kicked the ball, it would roll in the opposite direction, and so on. It would completely break everything we know about movement and momentum, and we have absolutely no examples of negative mass existing in our universe. Without negative mass, you can’t build a wormhole or a warp drive.

Second, the ability to go faster than light automatically permits backward time travel. As soon as you concoct methods to cheat the speed of light, you can set up scenarios where signals (or spaceships) can return to their origin point before they departed. This sets up all sorts of messy causality-violating situations and paradoxes, like dropping off a bomb to destroy your spaceship before it’s departed – but unless it departs, the bomb never gets delivered.

Read More: What Is the Grandfather Paradox of Time Travel?

Is Faster Than Light Travel Possible?

Since causality seems kind of important in our universe, with the past staying safely in the past and causes always preceding effects, violating that aspect of reality also seems like a no-go.

The speed of light limit is baked into the most fundamental relationship in the universe: the relationship between space and time as expressed through special relativity. Every single time we test that theory, we are also testing every other aspect of the theory, including its limitations of light speed. And special relativity is perhaps one of the most well-tested theories in all of science. For over a century, it has stood strong.

This isn’t to say that someday in the far future, humanity couldn’t concoct some new theory of physics that completely rewrites our understanding of speed, space, time and causality. Which makes it impossible to outright rule out faster-than-light travel. But for now it seems like we, and everything else in the universe, is permanently stuck in the slow lane.

Read More: Why Can't We Reverse the Arrow of Time?

Article Sources:

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review them for accuracy and trustworthiness. Review the sources used below for this article:

Britannica. Special relativity

Britannica. Speed of light

Britannica. Speed of sound

Quanta Magazine. Physicists Create a Holographic Wormhole Using a Quantum Computer

Phys.org. What is the Alcubierre "warp" drive?

NASA.gov. Negative Mass in Contemporary Physics

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Faster-than-light ‘warp speed’ interstellar travel now thought to be possible

I n another example of how truth is often stranger than fiction, scientists have taken a significant step towards turning the sci-fi concept of "warp drives" into a feasible reality.

According to Einstein's theory of relativity , going faster than the speed of light is off-limits in the real world. For this reason, warp drives, like the one powering spaceships in Star Wars and other science fiction movies, have always been firmly in the realm of imagination -- until now.

New research, led by Dr. Jared Fuchs from Applied Physics and published in the prestigious Classical and Quantum Gravity journal, presents a new solution to one of the long-standing challenges in realizing warp drive technology.

Traditional warp drive concept

The traditional sci-fi concept of a warp drive involves distorting spacetime in a very specific way: compressing it in front of the ship and expanding it behind.

In theory, this would allow the ship to effectively travel faster-than-light without actually exceeding the speed limit locally.

However, previous studies of this idea suggested that it would require exotic forms of matter with "negative energy density."

Understanding negative energy density

In our everyday experience, energy is always positive. Even in a vacuum, there is a small amount of positive energy called the " vacuum energy " or "zero-point energy."

This is a consequence of the Heisenberg uncertainty principle in quantum mechanics , which states that there are always fluctuations in the energy of a system, even at the lowest possible energy state.

The existence of negative energy density is highly speculative and problematic within the framework of known physics. The laws of thermodynamics and the energy conditions in general relativity seem to prohibit the existence of large amounts of negative energy density.

Some theories, such as the Casimir effect and certain quantum field theories, do predict the existence of small amounts of negative energy density under specific conditions. However, these effects are typically very small and confined to microscopic scales.

New approach to warp drive technology

This is where the new study comes in. Applied Physics researchers identified a new way in which warp technology might one day be possible. The team introduced the concept of a "constant-velocity subluminal warp drive" aligned with the principles of relativity.

The new model eliminates the need for exotic energy, using instead a sophisticated blend of traditional and novel gravitational techniques to create a warp bubble that can transport objects at high speeds within the bounds of known physics.

"This study changes the conversation about warp drives," said lead author Dr. Fuchs. "By demonstrating a first-of-its-kind model, we've shown that warp drives might not be relegated to science fiction."

Warp factory: Enabling warp drive spacetimes

The team's theoretical model for a new type of warp bubble uses traditional and innovative gravitational techniques, made possible with their publicly-available tool Warp Factory .

This solution enables the transportation of objects at high but subluminal speeds without the need for exotic energy sources. This can be achieved by engineering warp drive spacetimes to gravitate like ordinary matter, which is a first-of-its-kind solution.

"Although such a design would still require a considerable amount of energy, it demonstrates that warp effects can be achieved without exotic forms of matter ," added Dr. Christopher Helmerich, co-author of the study. "These findings pave the way for future reductions in warp drive energy requirements."

No g-forces for passengers

Unlike in planes or rockets, passengers in a warp craft experience no g-forces. This is a stark contrast to some sci-fi fantasies. The team's research shows how we might construct such a craft using regular matter.

"While we're not yet packing for interstellar voyages, this achievement heralds a new era of possibilities," explained Gianni Martire, CEO of Applied Physics. "We're continuing to make steady progress as humanity embarks on the Warp Age."

Dawn of faster-than-light travel?

The team at Applied Physics is now focused on addressing these challenges as they continue to refine their models and collaborate across disciplines and institutions to turn this once-fantastical dream into reality.

As we stand on the threshold of a new era in space exploration, the prospect of warp drives becoming a reality tantalizes us more than ever. With each new discovery and breakthrough, we inch closer to the stars and the boundless possibilities that await us in the vast expanse of the cosmos.

As humanity begins the chase for faster-than-light travel, perhaps using warp drives, we can only imagine the incredible adventures and revelations that the universe has in store for us.

The full study was published in the journal Classical and Quantum Gravity .

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A new physics-defying theory describes the effects of faster-than-light travel

Extended special relativity describes how the universe would look if you broke the speed of light..

Chris Young

Black hole concept with deep universe galaxy

gremlin/iStock  

Scientists from the University of Warsaw in Poland and the National University of Singapore are pushing the limits of relativity with a new theory called the “extension of special relativity,” a report from Science Alert reveals.

The new theory combines three time dimensions with a single space dimension (“1+3 space-time”), providing an alternative, mind-bending scenario to the three spatial dimensions and one time dimension we all know.

The scientists’ new study suggests that objects may be able to go faster than the speed of light without completely shattering our current laws of physics.

Ultimately, it describes how observations made by “superluminal” observers — observers traveling faster than the speed of light — may appear.

Extended special relativity

The new study , published in the journal Classical and Quantum Gravity , builds on previous work on these theoretical superluminal observers by some researchers on the project.

In their new work, they posited that superluminal perspectives could help to link quantum mechanics with Einstein’s special theory of relativity for a unified theory of quantum gravity . “There is no fundamental reason why observers moving in relation to the described physical systems with speeds greater than the speed of light should not be subject to it,” explained physicist Andrzej Dragan from the University of Warsaw in Poland.

The research team’s new model describes superluminal objects as resembling a particle that expands like a bubble through space, allowing it to ‘experience’ several different timelines in the process.

“Even so, the speed of light in a vacuum would remain constant even for those observers going faster than it,” the Science Alert report explains, “which preserves one of Einstein’s fundamental principles – a principle that has previously only been thought about in relation to observers going slower than the speed of light (like all of us).”

Importantly, the scientists argue that superluminal objects require descriptions within the field theory framework, meaning their extended special relativity should be logically consistent with past models. “This new definition preserves Einstein’s postulate of constancy of the speed of light in vacuum even for superluminal observers,” Dragan said. “Therefore, our extended special relativity does not seem like a particularly extravagant idea.”

A ‘feat worthy of the Nobel Prize’

The researchers aim to carry out more work to better understand the implications of their 1+3 space-time model. However, their initial analysis suggests that the particles of the Universe could all have incredible properties under the rules of extended special relativity.

“The mere experimental discovery of a new fundamental particle is a feat worthy of the Nobel Prize and feasible in a large research team using the latest experimental techniques,” explained physicist Krzysztof Turzyński, from the University of Warsaw.

“However, we hope to apply our results to a better understanding of the phenomenon of spontaneous symmetry breaking associated with the mass of the Higgs particle and other particles in the Standard Model, especially in the early Universe.”

Study abstract:

We develop an extension of special relativity in 1+3 dimensional spacetime to account for superluminal inertial observers and show that such an extension rules out the conventional dynamics of mechanical point-like particles and forces one to use a field-theoretic framework. Therefore we show that field theory can be viewed as a direct consequence of extended special relativity.

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