- #1
grantcallaway
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Hi all,
Please forgive my simplistic understanding on this, as I am a novice with an interest in Science, but I have the following question:
I've been reading a book on Einstein, and here's the stuff I get:
Speed is relative since there is nothing to "fix" a grid to which we know to be absolutely at rest. The speed of light is constant relative to anything, no matter how fast it is going, and this causes time to slow down at higher speeds relative to the observer. But my book only seems to explain this as related to only one observer (a light clock made by shining a laser across a train carriage, and comparing the distance the light travels according to the peson inside the carriage as opposed to the distance light travels relative to an observer standing on a platform).
So supposing I am the observer, and Tracy flies off into space at near the speed of light for say 50 years relative to me (which would be say 25 years relative to her). Assume we were both 30 when she left. When she returns, I would now be 80, but she would only be 55, right?
But then what happens from HER perspective? To her, I am the one moving, so in the time she ages 25 years, I would appear to have aged 12.5 years? So to me, I'm 80 and she's 55, but to her, she's 55 and I'm 42?
Alternatively, if we are certain that Tracy is the one actually moving, then surely speed becomes absolute?
Anyway - was wondering if you could shed some light? (Pardon the pun)
Please forgive my simplistic understanding on this, as I am a novice with an interest in Science, but I have the following question:
I've been reading a book on Einstein, and here's the stuff I get:
Speed is relative since there is nothing to "fix" a grid to which we know to be absolutely at rest. The speed of light is constant relative to anything, no matter how fast it is going, and this causes time to slow down at higher speeds relative to the observer. But my book only seems to explain this as related to only one observer (a light clock made by shining a laser across a train carriage, and comparing the distance the light travels according to the peson inside the carriage as opposed to the distance light travels relative to an observer standing on a platform).
So supposing I am the observer, and Tracy flies off into space at near the speed of light for say 50 years relative to me (which would be say 25 years relative to her). Assume we were both 30 when she left. When she returns, I would now be 80, but she would only be 55, right?
But then what happens from HER perspective? To her, I am the one moving, so in the time she ages 25 years, I would appear to have aged 12.5 years? So to me, I'm 80 and she's 55, but to her, she's 55 and I'm 42?
Alternatively, if we are certain that Tracy is the one actually moving, then surely speed becomes absolute?
Anyway - was wondering if you could shed some light? (Pardon the pun)