Jack and Jill are the same age. Jack leaves earth on a spaceship at 0.5c. Jill waits one year then sends a radio message (message goes at speed of light) to Jack telling him to return. Jack upon receiving the message returns immediately to earth. How much younger is Jack than Jill?
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Anonymous2007-03-02 12:29 ID:3SCLYgwE
speed of light isn't constant ;_;
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Anonymous2007-03-02 12:39 ID:gnGh3T1J
14 months.
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Anonymous2007-03-03 0:26 ID:Pn8NtJaH
gamma = 1/sqrt(1-0.5^2) = 2/sqrt(3)
Jack gets the message after he goes 1 light year, ie. after 2 years. He takes another 2 years to go back. So from his perspective 4/gamma = 3.46 years passed. Difference in age is 4 - 4/gamma = 0.54 years.
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FrozenVoid2007-03-03 14:30 ID:AQuvFQk0
Their ages don't change.I don't believe in this whole relativistical time dilation non-sense.
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Anonymous2007-03-07 14:05 ID:7mE+epxD
Spaceships are the secret to eternal youth!
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Anonymous2007-03-08 12:51 ID:xjlWkXyA
>>4
So Jack can change velocity from 0.5c to -0.5c in a negligible amount of time?
Good thing science isn't a democracy. There's enough proof that contradicts what you believe to soundly prove you wrong.
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Anonymous2007-03-12 0:02 ID:XNa7ZB4J
dude, physics are too subjective... just forget about and assume Jill is legal...
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Anonymous2007-03-12 4:01 ID:9HURC1wi
>>5
I believe in it only if light is a real limit. If people find a way to accelerate past the speed of light (impossible now, cause you'd need a negative mass but I dunno) then I don't think they will be travelling back in time.