Time Dilation

[Rosencrantz]

Hi hello I'm an engineer and this is my fortè.

Time dilation has a pretty interesting formula, but I'd say it's easy to grasp: the new time experienced equals T/sqrt(1-(v^2)/(c^2)). Basically, you're taking how fast an object is going, you square it, you divide it by the speed of light squared, then you take this number and subtract it from 1. Then you just root this number, and divide your base time constant by it. ~Simple~

But here's the kicker: it's all referential. It should be noted that time dilation felt is between two points: a reference "ground" and a reference "moving object". Like Sam said, everything in the universe is in motion. Everything. However, when we're talking dilation, we're getting into relativity. An object is moving fast in reference to another object. A car can drive at 60mph in reference to the Earth. We can complicate the issue by asking how fast that car is moving in reference to the Sun, but the kicker is that scientists and engineers (mostly engineers) don't like complicating math to begin with. So when we defined time dilation, we defined it in such a way that we can use celestial bodies (Earth) as baseline points for calculations.

So, when we refer to time dilation, we're talking about how much time is distorted *from a reference point*. The original time T in the equation I laid out could be how long it takes to count out 20 seconds on Earth, or maybe it could be how long it takes to count out 20 seconds on the Moon, or how long it takes to count out 20 seconds on some unidentified planet within the Andromeda Galaxy. It flat-out doesn't matter, because you're considering that this "time" is from a grounded point, and you assume this body is sitting still. The time distortion on a moving object would result directly in how fast this object is moving in reference to the grounded point.

Why can we do this? Suppose one car is moving at 65mph down a road, and suddenly a speeding car flies right past it (same road) at 120mph. We know both cars are moving, but to the person at the "grounded" point in the 65mph car, they will perceive that the car flying past them is moving forward at 55mph in reference to themselves. So to the 65mph car, the 120mph car is only moving at 55mph. I could go on and on about vectors and stuff like that (and stuff like how the two cars will perceive each other when moving in ~opposite~ directions), but I just wanted to illustrate why we can just use stuff like Earth referencing.

Also, we can safely say it's more than just theory. When astronomers launched a few satellites into orbit, they eventually began to notice that onboard clocks were moving too slow in reference to the clocks on Earth. Sure enough, when they calculated how fast these satellites were moving in orbit to get the correctional dilation value I mentioned above, plugging in their results fixed the problem!

Of course, the speed of light is considered a universal speed limit, and judging by that equation, we can probably assume that moving at the speed of light will very likely make time stop entirely for the object moving at that speed. The equation's going to be imperfect if we can prove that something can move faster than light, but that's for future study.