Did you know that time slows down at higher speeds?
On Sunday afternoon as we drove home from church, Jess and one of the young men were having a conversation about time and the speed of light and what makes one age. I piped up from the back seat, "Haven't you heard about that experiment where two guys start out the same age. One goes up in a space ship, then comes back years later to find out the other guy on earth is old?" I remembered the experiment, but I didn't remember exactly what it was illustrating. "Do you get it?" I asked, hoping I had made a point without really making one. Jess chimed in, "I get what you are saying, but what is the principle behind it?" After a long pause, an attempt at an answer, "It's got something to do with time see..." I had to say, "I'm not exactly sure. I can't remember."
Well, with a little jog of the memory and a little research, here we go:
The experiment of which I was recalling is called the twin paradox. Two men start out on earth, one (Bob) stays on earth while the other (Jim) gets in a spaceship and flies around for a while. When Jim comes back from his space travels to meet Bob, Bob has aged much more than Jim has, "You've got crows feet!" Jim says to Bob.
picture and more info here
While this experiment seems counterintuitive, it has been supported by atomic clocks taken on airplanes. Atomic clocks brought back to land after a flight are atomically slower (the change is fractions of a millisecond) when compared to an atomic clock that stayed on earth.
This slowing can be explained by special relativity (think E=mc2) and is quite complex (think equation upon equation and a discussion about inertial reference frames). The easiest way I can explain it is that while the twin is in the spaceship he accelerates when traveling, while the twin at home is constantly at rest. This acceleration causes time to slow down and thus, less aging. That is the answer in it's simplest terms. If you are interested in more (and believe me there is quite a bit more, I've been sifting through it for quite some time now) see here.
So, who needs the fountain of youth? Hop on a spaceship!
3 comments:
Excellent, BP Science Tuesday, excellent indeed.
Now, tell me what you can about length and speed. Isn't there something similar that explains that the measurement of length and/or height gets skewed as we move faster?
I'm really enjoying these BP science posts.
I own a book that delves into the subject and manages to give both a simple but complete explanation of relativity and the principles behind it. It doesn't look like much on the cover, but at only about 200 (small) pages it has some nice diagrams and straightforward explanations. I highly recommend it (The answer to Jo's question can be found there).
"The title?", you ask.
It's Relativity Simply Explained, by Martin Gardner ISBN 0486293157.
While reviewing past science tuesdays I came across this diagram once again... so perfect. I almost feel like I'm back in high school physics, which is pretty amazing because I never took high school physics :).
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