These hypothetical particles can travel faster than the speed of light

Since the Theory of General Relativity, the speed of light has a fixed value and it is impossible to exceed it, but some scientists disagree with that. For them, some hypothetical particles, such as tachyons, could travel so fast that it would take a lot of effort and energy to slow them down.

What is the speed of light?

Before understanding how tachyons could be faster than light – if they exist – and what would be the consequences of this in the universe, it is necessary to review some concepts of Albert Einstein’s General Relativity. After all, it was from her that the idea of ​​tachyons was conceived.

According to Einstein (and the many experiments that tested his theory) the speed of light is 299,792,458 km/s, regardless of the frame of reference. This means that if you are in a spaceship at near the speed of light and you turn on a flashlight, the beam of light emitted by it will still be at the speed of light relative to you. That in itself is amazing, but that’s not all.

Want to catch up on the best tech news of the day? Access and subscribe to our new youtube channel, Canaltech News. Every day a summary of the main news from the tech world for you!

Einstein’s theory also shows us that space and time are a single entity, simply called “space-time”. They cannot be separated, and this implies that a journey through space is also a journey through time, and vice versa. This creates some curious effects, which have indeed been confirmed by science. One of these effects is that time passes faster for a stationary person, while it passes slower for a moving person (to put it simply).

Illustration of NASA’s Probe B spacecraft, which proved space-time distortion in Earth’s orbit (Image: Reproduction/NASA)

In 1972, physicist Joseph C. Hafele and astronomer Richard E. Keating performed a test to see if this effect was true. They put atomic clocks on jet planes that circumnavigated the Earth in opposite directions. At the end of the experiment, the clocks on the two planes, and a third clock that remained in Washington, showed differences on the order of hundreds of nanoseconds.

Another important effect is that anything that affects space — such as distortions caused by the gravity of a massive object — will also affect time. For example, Earth’s gravity causes space-time to have a “dragging” effect, as demonstrated by NASA’s 2004 Probe B probe.

Finally, physicists consider it impossible to surpass the speed of light for a simple reason: anything with mass, even particles like protons, neutrons and electrons, would have to gain infinite mass to reach the “forbidden” speed of light. The reason is that as you approach that speed, the mass of an object becomes almost infinite, as does the energy needed to accelerate it. And, also according to Einstein, mass and energy are intrinsic (photons of light have no mass).

But what does all this have to do with tachyons? Well, everything — as we’ll see below.

Is it possible to travel faster than the speed of light?

Illustration of an astronaut traveling in a spaceship at the speed of light (Image: Reproduction/NASA)

Officially, we cannot travel faster than light except particles in a medium other than a vacuum, such as water. But there are scientists who decided to propose some ideas that contradict Einstein’s postulate, without violating the laws of known physics — which is important when it comes to a scientific hypothesis. This is the case for tachyon proponents.

First presented in a 1967 scientific paper entitled “Possibility of particles faster than light”, by physicist Gerald Feinberg, tachyonic particles would emerge from a quantum field with “imaginary mass”, or anti-mass. Why is it important? Remember that mass and energy are intrinsic? To overcome light, it is necessary to work “in reverse”.

In simpler terms, add energy and impulse to common particles (protons, neutrons, electrons, etc.) and they accelerate. add energy and boost
in tachyons, and they slow down. That’s right, to slow down a tachyonic matter, we would have to apply energy. The speed of light is the lower limit of a tachyon, that is, they could never be slower than 299,792,458 km/s.

If a tachyon has zero energy, their speed will be infinite, and they could cross the universe instantly. Take gas, for example—if it’s made of bradions (the name the tachyon theory gives to ordinary particles), it will cool as it expands and the particles slow down; but a tarchy gas heats up when it expands and its particles accelerate, until reaching infinite velocity. At that point they cease to exist.

To date, the Tarchyons have not been detected. Physicists attribute some explanations to this, such as the fact that it is impossible to detect something that fast with our sensors, which operate within the limits of the speed of light. But maybe there are ways to detect them, because if they have “anti-mass” it means they still have some energy associated with mass.

If true, they must have some gravitational effect, then it’s possible that highly sensitive detectors could find them. Another method of detection may arise from its very nature faster than light, but this is really correct, these particles would bring us some… bizarre consequences.

What happens when you travel faster than light?

If tachyons exist, the universe could be faced with paradoxes as complex as the famous grandfather paradox—if a time traveler went back in time and killed his grandfather, the traveler could never have been born. And if he wasn’t born, his time travel wouldn’t be possible either. If he has not traveled back in time, the grandfather has not been killed, then the traveler is born. So he travels back in time, and… well, you’ve already “get the idea”.

In the case of tachyons, the problem is similar because, for some observers, tachyons travel backward in time. As an example, the figures below show a tachyon at certain events and observers at different points in space-time. Event A is the sending of a signal through a tachyon and event B is the receipt of that signal.

If this signal is traveling at the speed of light, or slower, all observers in the different frames agree that event A happened before B. But if this signal is carried by a tachyon and therefore moves faster than In light, there will be frames of reference that say the signal was received before it was sent. So, to an observer in this picture, the particle has traveled backward in time.

The animation illustrates concurrency; the white lines move from past to future in the respective frames (green coordinate axes), highlighting the events that occur in them (Image: Playback/Acdx/Relativity of Simultaneity Animation/Wikimedia Commons)

The image may “deceive” your judgment and suggest that the correct view is in the frame where the speed is less than that of light. But one of the fundamental postulates of special relativity is that the laws of physics must be the same in all frames of reference. In other words, all points of view, no matter where you are in spacetime, are valid. If tachyons can violate causality and move backward in time relative to one frame of reference, it can do so in all of them.

Another way of looking at the problem is with a tachyon being emitted by a spacecraft pilot named Alberto to a receiver on Earth named Estevão. The tachyon signal will move faster than the light in Alberto’s frame of reference, but it will go backward in time in Estevão’s frame of reference. So Estevão sends a response that moves faster than light in his frame of reference, but backwards in time in Alberto’s frame of reference.

In this situation, Alberto could receive the response before sending the original signal. If that response signal says “send no signal”, Alberto will obey by not sending. Thus, Stephen would receive nothing, and would have nothing to respond to. Stephen will never send the signal that says “send no signal”, and events happen in the same way as in the grandfather’s paradox.

For now, light is the fastest sprinter in the universe (Image: Reproduction/twenty20photos/Envato)

Thus, tachyons not only violate causality in all structures, they also open the door to serious logical paradoxes. There are suggestions for how these paradoxes can be avoided. The simplest thing is that tachyons don’t exist, but that takes the fun out of it. So, we can propose that observers in different frames cannot tell the difference between the emission and absorption of tachyons.

Another suggestion is that tachyons are not like any other particle we know and don’t interact with anything, and can never be detected or observed (we hope that’s true, as we spare future physics students the paradoxes caused by these particles, if they do. proven one day). So, Alberto could never send a tachyon to Estevão, as there is no way to produce or control them.

Leave a Comment