A barrier that prevents anything with mass from moving speed of light It doesn’t just represent the limits of engineering or the failure of the imagination. As expressed by , it is baked into the very laws of the universe. Einstein’s Special Theory of Relativity.
Let’s say we want to start traveling faster than the speed of light. You start by resting and fine-tuning yourself a little. Because of the mass, the nudge has to overcome a bit of inertia to move it forward, but it does in the end. For example, light a rocket and launch it.
Related: Why is the speed of light the same?
But once it leaves the launch pad, it doesn’t stop. It has a super-advanced engine that you can keep pushing and keep accelerating. At speeds much slower than the speed of light, it all makes sense. You get the same amount of acceleration and speed boost every time you start the engine.
But as you approach the speed of light, strange things start to happen. Putting the same amount of energy into the engine results in less and less acceleration, resulting in less cost-effective speed. Despite pushing the engine to extremes, you find yourself slowly approaching the speed of light, but never reaching it. At some point, you realize that to reach the speed of light, you have to put an infinite amount of energy into the engine, but it doesn’t.
The problem here is that energy is mass, given by E = mc^2. The faster you move, the more kinetic energy you get. As we approach the speed of light, the mass becomes infinite, so reaching the speed of light requires infinite rocket power.
However, these rules apply to objects whose mass begins below the speed of light. Like light itself, massless objects automatically move at the speed of light, never slowing down or accelerating. In 1967, based on decades of research, physicist Gerald Feinberg proposed a new class of particles: objects with “imaginary mass.” (Here “imaginary” refers to the mathematical term for the square root of -1.) These particles are Tachyon,right I never have It travels slower than the speed of light. In fact, they are forced to exceed the speed of light all the time, making it as difficult to slow down to it as it is to try to accelerate to it.
Feinberg was not the first to consider faster-than-light particles, but he was the one who coined our term. einstein After playing around with ideas, I discovered that such particles violated the central rule of the universe: causality.
Cause-and-effect relationships are very basic and underlie everything we understand about how the universe works. Simply put, it is a state of causality in which the cause must come before the effect. You have to text before your phone rings, you have to put cheese in your mouth before you eat, and so on.
But tachyons can break causality. To understand how, let’s set up a little thought experiment.i’m sitting on earth while on an epic adventure in space. I want to send a tachyon signal, so I activate the tachyon transmitter and send a message.
From my point of view, tachyons are moving away from me faster than the speed of light. So far, so good.
If you stand perfectly still, eventually the tachyons will arrive in less time than the light will. You won’t see a tachyon coming until it passes by, but it’s still not a big deal. If you point your telescope at me, you will receive a tachyon before I press the button and see the image I am sending. Just curious, but still no big deal.
The problem arises when it starts to move. In relativity, from your point of view, you are stationary while the Earth appears to be receding. This causes a time delay. From your point of view, everything in the universe slows down, including my button presses. In fact, if you’re moving fast enough, you can receive my tachyon and send a reply before I hit the button in the first place. You can send the signal in time.
Once you can send signals into the past, you can play many fun games of contradiction. You can message back to prevent grandparents from seeing each other. This means that you will never exist, but you must exist to go back in time to prevent your grandparents from meeting. You can even destroy your past self.
And since we don’t live in a universe where these contradictions and violations of causality occur, it seems unlikely that tachyons exist.
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