Can We Travel Faster Than Light?

The hypothesis of particles whose speed exceeds that of light (tachyons) has been proposed, but their existence would violate causality and would involve time travel. The scientific consensus is that they don't exist. Physicists' current understanding of space-time comes from Albert Einstein's theory of general relativity.

General Relativity

states that space and time are merged and that nothing can travel faster than the speed of light. General relativity also describes how mass and energy deform space-time: heavy objects such as stars and black holes curve space-time around them.

This curvature is what you feel as gravity and the reason why many space heroes worry about “getting stuck” or “falling” into a gravity well. Early science fiction writers John Campbell and Asimov saw this deformation as a way to circumvent the speed limit. It's true that in special relativity, nothing can move faster than light. But special relativity is a local law of physics. Or in other words, it's a local law of physics.

That means that you will never, ever see a rocket fly next to your face faster than the speed of light. The universal speed limit, which we commonly call the speed of light, is fundamental to the functioning of the universe. It's difficult to visualize this if you've never heard of it before, but scientists have discovered that the faster you go, the more your spatial dimension decreases in the forward direction and the slower your watch works when viewed by an outside observer. In other words, space and time are not a fixed background in which everything happens the same way as always. Instead, space and time can be warped and bent.

If you look at the equations that are at the heart of Einstein's theories of relativity, you'll discover that, as you approach the speed of light, your spatial dimension in the forward direction decreases to nothing and your clock slows down to a stop. A frame of reference with zero width and no progression over time is really a frame of reference that doesn't exist. Therefore, this tells us that nothing can go faster than the speed of light, for the simple reason that space and time don't really exist beyond this point. Because the concept of speed requires measuring a certain amount of distance traveled in space over a certain period of time, the concept of speed doesn't even physically exist beyond the speed of light. In fact, the phrase “faster than light” has no physical meaning. It's like saying darker than black.

You could say that maybe Einstein's theories of relativity are wrong. However, there is now so much evidence that supports relativity that, if it's wrong, it will have to be wrong to a small extent that doesn't change these basic principles. The restriction that nothing can travel faster than light isn't as limiting as it seems. A more precise statement of the principle would be that nothing can travel locally faster than light. This means that, in fact, we can acquire effective speeds faster than light if we use non-local scales.

For example, if there are wormholes, you can use one to take direct access from Earth to the North Star. Compared to a little bit of light that traveled from Earth to the North Star and didn't go through the wormhole, you would have been traveling faster. In other words, you would have arrived at the North Star first. This is allowed because you never locally exceeded the speed of light. If a different beam of light were sent from Earth to the North Star and went through the wormhole with you, there's no way you could run faster than him.

As another example, there are some distant stars in the universe that are moving away from each other at a speed greater than the speed of light. This is allowed because it is not a local speed. This would indicate that it would probably not be desirable to make a human travel faster than the speed of light. However, let's say that you can somehow compress the space between you and point B so that the interval is now just one meter. In theory, this approach doesn't contradict the laws of relativity, since you don't move faster than light in the space around you. In this case, space-time expands, but material in spacetime continues to travel within the limits of the speed of light.

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. The most obvious visual example of this occurs in rainbows, which tend to have long and fast red wavelengths at the top and the shortest and slowest violet wavelengths at the bottom, according to a publication by the University of Wisconsin-Madison (opens in a new tab). Keep in mind that objects start closer than the time it takes for light to travel between them, light is redshifted due to the expansion of space, and the two galaxies end up much farther apart than the path of light that travels through the photon exchanged between them. However, according to Cassibry, there is something else to consider when talking about things that move faster than the speed of light. Like raisins in a loaf of raisin dough, all galaxies in the Universe see other galaxies moving away from them, and more distant raisins (or galaxies) seem to be moving away at a faster rate.

Allain is also sure that going faster than light is far from likely, but, like Cassibry, he pointed out that if humans want to explore distant planets, it may not be necessary to reach those speeds. The restriction that nothing can move faster than light only applies to the movement of objects through space. Allain is also sure that going faster than light is far from likely but he pointed out that if humans want to explore distant planets it may not be necessary to reach those speeds. The concept behind this idea is simple: instead of trying to break through physical barriers like reaching speeds greater than the speed of light, we can use non-local scales such as wormholes or curved spacetime for our advantage. By doing so we can effectively travel faster than what was previously thought possible without actually breaking any laws or principles. In conclusion we can say with certainty that nothing can move locally faster than the speed of light. However there are ways we can acquire effective speeds greater than what was previously thought possible by using non-local scales such as wormholes or curved spacetime for our advantage.