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Enter the Relativity Challenge
An anonymous reader writes "Any slashdotters wanna pick up a lazy 25,000 Euros? All you have to do is explain Einstein's theory of relativity in a five minute multimedia presentation. The Pirelli Group have laid down this 'Relativity Challenge' to anyone as part of the International Year of Physics. Entries close on 31 March 2005."
"A Man has got to know his limitations."
I found mine in Physics 21 when we hit Relativity. I just flat out don't get it. I can do the math, and get the right answers, but I couldn't truly explain it.
"As God is my witness, I thought turkeys could fly." A. Carlson
Einstein's work was already in very simple laymen's terms. I don't know what the point is in trying to make it into braindead powerpoint.
I've had enough abrasive sigs. Kittens are cute and fuzzy.
...just remember that PowerPoint is not "multimedia."
Yeah, right.
Explain females to the slashdot crowd in 4 minutes, and I'll give the winner a copy of Duke Nukem Forever
Don't forget that this is the "SPECIAL Relativity Theory" - not the "GENERAL" one...
I found is in Relativity and FTL(faster than ligth) FAQ http://www.physicsguy.com/ftl/
This explanation explain relativity in context with the faster than light travel. Needs elementary math and explains lucidly why the time dilation occurs. Highly recommened.
When you are courting a nice girl an hour seems like a second. When you sit on a red-hot cinder a second seems like an hour. That's relativity. -Einstein
I don't think it can be said much better.
The best relativity resource I've found is an in-depth online book called "Reflections on Relativity". Be warned, it's the real deal; read it slowly and carefully. Intro calculus should suffice to get you through chapter one (which took me about two weeks spare time in the evening to read and digest), after that it gets tougher, although I'm finding the subjects don't build on each other so much after that so you can skip something you can't follow and keep going. (On the other hand, I only just finished Chapter 2, of 9.)
:-)
About the only thing I can tell you, short of linking the book as I did or quoting it more extensively than Slashdot will allow, is that nearly everything physics fanboys think they know is wrong. Don't rely on Star Trek for your physics, get the real deal; it'll only take as much time as a few episodes of Star Trek and you'll feel much better about your expanding horizons
You can't just wave it off saying the one that experienced the accelleration will have their clock slow down. If you want to calculate how much less one person aged, you go by how long (time and distance) they were travelling at that speed. For example, if I accellerate to 0.999999c in about a year (I think that's about 1g accelleration) and travel 10 light-years and back, then 24 years will have passed on Earth (20 travel + 4 for accelleration), but I will have aged only about 4. If I undergo the same accelleration but travel 10,000 light-years and back, then 20,004 years will have passed on Earth, but I will still have aged only about 4. The accelleration didn't make time pass more slowly, it was the period while I was tavelling at high speed that made it pass more slowly. Take both examples together and the one would seem to have 4 years pass and the other would seem to have 19,984 years pass, even though they experienced the same accellerations.
This also leads to an absurd result from my point of view. I will have only seen 2 years go by, but I will have travelled 20,000 light-years. From my point of view I would have been travelling 10,000 times the speed of light. How can this be?
I think it has to do with contraction. Lorentz contraction is one thing I haven't understood, how you can measure the length of something that is going nearly the speed of light? Apparently, when you are going nearly the speed of light, everything else contracts in the direction of your travel. For instance, if you were going a certain speed and passed a meter stick, it would appear to be only 1 millimeter long, although a stationary observer by the meter stick would see it as 1 meter long.
Now as for how fast you are going, that is all relative as well. If I take off from earth and accellerate to 0.999999c for about a year and travel 10 light-years, I don't think I'm going 10 light years. Space and the galaxy will seem to contract along the direction of my motion. When I get 10 light-years in space, it will appear to me like I have travelled a much shorter distance.
Here's a more concrete example. Let's say that I pass Earth going at velocity V, which slows down time for me to 1/10th normal. Then I travel to a space buoy that you have measured from earth as 10 light years away. Not only will I reach that buoy in about a year, but I will think I have travelled much less than 1 light-year because space along my direction of motion has contracted. During that time, an earth-based observer thinks 10 years have passed. The reason that his clock doesn't appear to slow down for me is because I don't think he's travelling that fast. To me, he has travelled much less than 1 light-year because space contracted and I think it was in 1 year, so he is travelling much slower than the speed of light and subject only to minor relativistic effects.
From this explanation. Twin A stays on Earth and Twin B sets off in a spaceship going 0.995 c (time and space will dilate to 1/10th). He reaches a point C that is 9.995 light-years away and heads back at the same speed. Let's assume accelleration is instantaneous. When Twin B leaves earth, both twins agree their clocks read zero. When Twin B reaches point C, Twin A sees that his clock reads 10 years and Twin B's clock reads 1 year. Twin B thinks his clock reads 1 year and Twin A's clock reads 0.1 year. As soon as he turns around, Twin A still thinks B's clock reads 1 year and his clock reads 10 years, but Twin B thinks his clock reads 1 year and Twin A's clock reads 19.9 years. It all depends on your frame of reference, and the accelleration changes that.
Personally, I don't think I will ever understand it. I think it's all philosophical because it is dependant on definitinitions. What does "observe" mean. What is "simultaneous"? Until you start studying special relativity, these terms are pretty easy to understand. I think physicists should come up with new words to describe these relativistic concepts and not use "observe" and "simultaneous" anymore in physics discussions. I have a special relativity textbook and the book contradicts itself on the meaning of those words in the first few chapters.
How stuff works in Einstein's theory of special relativity? is a good starting point for the contesters.
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