Time Stops at the Speed of Light
According to Einstein’s Theory of Special Relativity, the speed of light can never change—it’s always stuck at approximately 300,000,000 meters/second, no matter who’s observing it. This in itself is incredible enough, given that nothing can move faster than light, but it’s still very theoretical. The really cool part of Special Relativity is an idea called time dilation, which states that the faster you go, the slower time passes for you relative to your surroundings. Seriously—if you go take a ride in your car for an hour, you will have aged ever-so-slightly less than if you had just sat at home on the computer. The extra nanoseconds you get out of it might not be worth the price of gas, but hey, it’s an option.Of course, time can only slow down so much, and the formula works out so that if you’re moving at the speed of light, time isn’t moving at all. Now, before you go out and try some get-immortal-quick scheme, just note that moving at the speed of light isn’t actually possible, unless you happen to be made of light. Technically speaking, moving that fast would require an infinite amount of energy.
Alright, so we just finished agreeing that nothing can move faster than the speed of light—right? Well… yes and no. While that’s technically still true, at least in theory, it turns out that there’s a loophole to be found in the mind-blowing branch of physics known as quantum mechanics.Quantum mechanics, in essence, is the study of physics at a microscopic scale, such as the behavior of subatomic particles. These types of particles are impossibly small, but very important, as they form the building blocks for everything in the universe. I’ll leave the technical details aside for now (it gets pretty complicated), but you can picture them as tiny, spinning, electrically-charged marbles. Okay, maybe that’s kind of complicated too. Just roll with it (pun intended).So say we have two electrons (a subatomic particle with a negative charge). Quantum entanglement is a special process that involves pairing up these particles in such a way that they become identical (marbles with the same spin and charge). When this happens, things get weird—because from now on, these electrons stay identical. This means that if you change one of them—say, spin it in the other direction—its twin reacts in exactly the same way. Instantly. No matter where it is. Without you even touching it. The implications of this process are huge—it means that information (in this case, the direction of spin) can essentially be teleported anywhere in the universe.
Light is Affected by Gravity
But let’s get back to light for a minute, and talk about the Theory of General Relativity this time (also by Einstein). This one involves an idea called light deflection, which is exactly what it sounds like—the path of a beam of light is not entirely straight.Strange as that sounds, it’s been proved repeatedly (Einstein even got a parade thrown in his honor for properly predicting it). What it means is that, even though light doesn’t have any mass, its path is affected by things that do—such as the sun. So if a beam of light from, say, a far off star passes close enough to the sun, it will actually bend slightly around it. The effect on an observer—such as us—is that we see the star in a different spot of sky than it’s actually located (much like fish in a lake are never in the spot they appear to be). Remember that the next time you look up at the stars—it could all just be a trick of the light.