Time Dilation

[Koh]

I've just been reading up on the theory of Time Dilation, and found it quite interesting.  I'm no science major, but the fact that we've basically delved into the concept of time travel, even if it's only one way, intrigues me.


As a sort of summary, Time Dilation occurs when an object is moving faster relative to another stationary or slower moving object.  The closer the faster object's speed reaches the speed of light, the more time dilation occurs.  There were a few experiments performed, the most popular being the atomic clock experiment, the information of which is provided on the above link.

This is basically a theory on one way time travel, in that if one were to constantly move at such high speeds compared to everyone else on Earth for X period of time, they'd go into the future by Y amount of time, while Z amount of time has passed for those on Earth, where Y < Z - X.

Has anyone heard of this theory before?  What are your thoughts on it?

[Gors]

I've heard about it and yeah, basically time passes quicker the more you're near speed of light.

Unfortunately, if anything were to move on such speed of 30,000 km/s (which means it'd go around the earth three times in just 4 seconds), the attrition caused by air would be so much that it would literally burn it into dust.

Interestingly, as you said, time passes quicker when you're near speed of light, but what if you can achieve a faster speed, such as black holes, whose gravitational force is so high that not even light, with its massive speed, can't overcome it? If there were two people, A and B, near a black hole, and B decided to enter it, A would see him entering slowly until B has touched the hole's boundary, where he is automatically sucked by gravity. The image of the last moment of B entering the hole will stay visible for A, while becoming reddish in hue (a phenomenon known as Redshift; which is the visual equivalent of the Doppler Effect, that weird distortion you hear in sound when a car in movement is playing a sound). As for B, he will not be able to see A anymore as the light reflecting off from A will be all distorted with the massive gravitational force, but if he could, he would be able to see A withering and dying almost instantly, as well as seeing Earth end, and other weird oddities. Time inside the black hole passes absurdly fast, and even if B survived in there, he wouldn't be able to leave it or send any data out from the hole, being trapped in a point of no return (also known as Event Horizon). Which is unfortunate, because if someone could enter a black hole and send data from it, we would be able to know how a black hole behaves from inside, which would solve a shitton of science's current problems and unsolved physics questions.

[Raccoon Sam]

Funny thing – you're not the center of the universe! We're all on earth, and earth is constantly spinning a solid 1040 miles per hour. Not only that, but earth is also moving at 67 062 miles per hour around the sun.
So technically we're all always moving pretty fuckin' fast. So if you go to the moon or just fly to space and stay still for a bit, you'll have experienced time dilation. Not because you're literally moving at blazing speeds, but because everyone else is.

[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.

[Gors]

Adding to that, even if we are moving fast for spinning with the Earth around the Sun, it really doesn't compare to the speed of light. Let's remember that it's 30,000 km per second, not hours. It's just really too fast.

I think that this, allied to the fact that satellites are installed really far from us, is what gives out that weird delay in TV news, when an announcer is talking with another who is in a different place: the signals take time to reach the satellite and be directed to the target person, but I'm not so sure. Feel free to correct me if I'm wrong.

[Rosencrantz]

Really, I think those delays are more due to system processing rather than signal transmission. Anything that's wireless uses some sort of radio spectra, and radio is electromagnetic radiation (aka. light), so those signals are definitely moving at the speed of light. The delay probably comes in because a) the transmitters from on-site cameras and microphones need to convert and transmit everything to a radio wavelength tansmission, b) the satellites collecting the transmissions need to process then redirect the transmissions to an off-site receiver, and c) the receiver has to convert everything back to a readable audio/video format for the news stations to interpret. All of that does take quite a bit of computing to make work.

[Gors]

I really like how things are made to work, it's really mesmerizing that we, as humans, were able to create such stuff. It's astonishing.

[TomGuycott]

You guys are too smart for me.