Einstein's laws of general relativity have many practical and theoretical applications within the realm of space-time. One particularly neat thought experiment I encountered was the supporting theory that you would actually age at a slower rate if you were to travel at speeds closer to that of light, as described in the following link.
http://www.einstein-online.info/spotlights/Twins
Assuming two humans were born at [approximately] the same time on Earth and one takes off in a rocket travelling any substantial fraction of the speed of light and the other twin stays behind, the idea is that the one who returns will have aged, say, a few years, while the one remaining aged about 40 years. At first you might be inclined to argue this is a paradox because Einstein's law say that motion is relative so that from the travelling twin's perspective, the other one is moving away from her at the near the speed of light. After all, external clocks appear slower when you're moving by them at substantial speeds due to time dilation. In the first link below, Carl Sagan explains in a different light the presence of the apparent Doppler red and blue shift effects at super high velocities within this aging thought experiment. He mentions that if both twins were wearing watches, they would be ticking at the same rate according to the respective owner of it. However, since the travelling one is going so much faster, she is not always an inertial observer and the effects of gravity are not as strong like for the one left on Earth, whose speed is too insignificant to .
For example, if I were hurtling through space at .95 the speed of light, then from my frame of reference everything outside of my rocket will be appearing to move at that very high speed as well. But to me, my watch still ticks at the same rate it did since I left. If a beam of light were travelling next to me, it would appear slower than usual. Thus since the speed of light is constant, the only explanation for it looking slower to me is that time itself had to slow down. I can't tell of course while this is happening, because it's all relative, but time on Earth will have been going at a faster rate throughout this trip because it is smaller in relation to light's velocity. This thought experiment is extremely hard to grapple with, thus corrections and comments are more than welcome.
http://www.youtube.com/watch?
http://www.pbs.org/wgbh/nova/einstein/hotsciencetwin/
Other relevant links on space-time, gravitational lensing, and relativity:
http://www.spacetimetravel.org/tompkins/tompkins.html
http://www.spacetimetravel.org/tompkins/node7.html
http://www.nap.edu/jhp/oneuniverse/motion_40-41.html#section
Your post is a great look into the theory of relativity as we have learned about it in class, and you did a nice job summarizing the ideas in an understandable way. Your discussion brings time dilation into conversation, where clocks that are moving will report times that are slower than stationary ones. This is due to the nature of spacetime, where time slows at higher speeds of the reference frame relative to another reference frame. This was an exciting and informative explanation of these concepts, awesome job!
ReplyDeleteI think you did a very good job explaining the theory of relativity considering how difficult it is to understand this concept. Your diagrams definitely helped to understand that the closer your speed it is to the speed of light, then the slower your clocks will move. Of course, this is hard to grasp since everything is relative. I think it is so interesting that the person moving close to the speed of light will see their time as normal, but a person moving slower will see their clocks as moving way faster.
ReplyDeleteI agree that you did an awesome job explaining the theory of relativity. I think it would be interesting to learn more about the very subtle implications of the differences in time that exist on earth and the implications that they might have for reality.
ReplyDeleteI agree with the others, you did explain this fairly well. As I learned from a video on youtube talking about general relativity, the closer an object reaches the speed of light, time moves slowly. And when an object reaches the speed of light time stops completely. However, I didn't quite get the last two diagrams you showed. A bit more explanation would be great.
ReplyDeleteHere is the link to the video I was referring to: http://www.youtube.com/watch?v=ev9zrt__lec the video is kind of long but it explains everything in great detail. It also includes time dilation as well
ReplyDeleteI think this is a very interesting topic you picked out, and you explained it in a very simple to understand way. The more I try to make sense of this theory, the more perplexing it gets. The fact that the closer you get to the speed of light the slower time gets correlates with the fact that light can show us what happened billions of years ago. This shows that at the speed of light information is not affected by time and will remain forever unchanged. However, I wonder if this is also true for more massive objects. It is even more confusing to think about why time seems to slow down when get closer to the speed of light. For someone observing you moving very fast, time is passing slower by you, but for you time is still behaving normally. The thing I am confused about is whether or not you would still experience 40 years worth of time passing by, and therefore be able to do 40 years of work but only age a couple of years.
ReplyDeleteIn response to eri's post, I believe that you would not be able to do 40 years worth of work while only aging a couple of years, because from your frame of reference, only a couple of years went by. Think about it in terms of your watch, it would tick at the same rate, so your days would feel like the standard amount of time as they would on earth. However, on earth, time would be going "faster" relative to you.
ReplyDeleteWhat I'd be interested in knowing is if you would age a couple of seconds slower if you were born and then spent your entire life traveling at 60 mph in a car.
This is a well explained post on how time is relative. It's interesting to think that we could potentially evade aging through travelling at different speeds through time. It is also kind of strange to think that while one person is on the earth aging at one speed and another person is travelling closer to the speed of light that to each of them their own time does not appear any differently.
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