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Is the reason that nothing can go faster than light because we have not tried hard enough?
Category: Physics
Published: July 20, 2017
By: Christopher S. Baird, author of The Top 50 Science Questions with Surprising Answers and physics professor at West Texas A&M University
No. The universal speed limit, which we commonly call the speed of light, is fundamental to the way the universe works. It is difficult to visualize this if you have never heard about it before, but scientists have found that the faster you go, the more your spatial dimension in the forward direction shrinks and the slower your clock runs when viewed by an external observer. In other words, space and time are not a fixed background on which everything takes place in the same way it always does. Instead, space and time can warp and bend.
If you look at the equations which are at the core of Einstein's theories of relativity, you find that as you approach the speed of light, your spatial dimension in the forward direction shrinks down to nothing and your clock slows to a stop. A reference frame with zero width and with no progression in time is really a reference frame that does not exist. Therefore, this tells us that nothing can ever go faster than the speed of light, for the simple reason that space and time do not actually exist beyond this point. Because the concept of "speed" requires measuring a certain amount of distance traveled in space during a certain period of time, the concept of speed does not even physically exist beyond the speed of light. In fact, the phrase "faster than light" is physically meaningless. It's like saying "darker than black."
You might say that maybe Einstein's theories of relativity are wrong. However, there is so much evidence now supporting relativity that, if it is wrong, it will have to be wrong in a small way that does not change these basic principles.
The restriction that nothing can travel faster than light is not as limiting as it seems. A more accurate statement of the principle would be, "nothing can locally travel faster than light." This means that we can indeed acquire effective speeds faster than light if we use non-local scales. For instance, if wormholes exist, you could use one to take a shortcut from earth to the North Star. Compared to a bit of light that traveled from earth to the North Star and did not go through the wormhole, you would have been traveling faster. In other words, you would have reached the North Star first. This is allowed because you never locally exceeded the speed of light. If a different beam of light was sent from earth to the North Star and did go through the worm hole with you, there is no way you could outrun it. As another example, there are some distant stars in the universe that are moving away from each other at a speed faster than light. This is allowed because it is not a local speed.