 | | Relativity Question
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| If a ship travels for 5 light years at .5c, for whom will the trip take 10 years? The occupants or an observer outside the ship? Jude (24 years ago, 7-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| (...) heh. depending who you ask. for the dude in the ship, the _world_ is moving at .5c, and so the world is aging slower. (btw, it's not a 1/x ratio, I think it's closer to a 1/x^2, but highschool was a long time ago...). For the people on earth, (...) (24 years ago, 7-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| (...) Let me rephrase the question: If a man travels on a ship away from earth for 5 light years at .5c, then returns to earth at .5c, who will have aged 20 years, the occupant or his twin who stayed on earth? Jude (24 years ago, 7-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| (...) laf. That's the paradox. I think we won't know until we try it. I've seen physicists get cross eyed thinking about it. Some say that _no_ time will pass at all! But again, this is what I remember from highschool, and my memory isn't that good (...) (24 years ago, 7-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| (...) As I understand it, the time dilation will occur for the occupant of the fast-moving ship, who will experience dilation relative to the stationery observer. The traveler won't notice the slowing of time, since everything in his frame of (...) (24 years ago, 7-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| (...) I dunno. Who is undergoing the acceleration? ;) James (24 years ago, 7-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| (...) no, he's right, it's terrible. :) (24 years ago, 7-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| (trimmed out .space - they don't care!) (...) but isn't that the whole point of relativity? who's moving and who's standing still? (24 years ago, 7-Nov-00, to lugnet.off-topic.geek)
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| (...) Hi, let's do some math. IIRC T = t/(sqrt(1 - (v/c)^2) where T: time elpased for stationery observer t: time elapsed for moving observer v: velocity of moving observer c: speed of light assuming minimal acceleration. T = 11.5 yrs. Experiments (...) (24 years ago, 7-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| Hi. | | Let's see what I can remember. | |> > On Tue, Nov 07, 2000 at 08:41:38PM +0000, Jude Beaudin wrote: |> > > Let me rephrase the question: |> > > If a man travels on a ship away from earth for 5 light years at .5c, |> > > then returns to earth (...) (24 years ago, 7-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| (...) Using this formula someone else posted: T = t/(sqrt(1-(v/C)^2)) The amount of time experienced by the twin that stays behind would be 26.67 Years. This sounds right. The longer he was gone, and/or the closer to the speed of light (C) that he (...) (24 years ago, 7-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| (...) Well, I usually like to consider myself the Lorenz Reference Point of the universe, so it's anyone who's accelerating relative to me! Seriously, I see what you're saying--to the person in the ship, the "stationary observer" (which, by the way, (...) (24 years ago, 7-Nov-00, to lugnet.off-topic.geek)
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| (...) I think the answer is that we'll all grow old faster by stressing ourselves out trying to solve this. :-) Don't forget that the Theory of Relativity is just that, a theory. Also, it's based on the assumed constant of the speed of light. The (...) (24 years ago, 7-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| (...) Everyone is moving. (24 years ago, 7-Nov-00, to lugnet.off-topic.geek)
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| | | | | | Re: Relativity Question
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| Jude Beaudin <shiningblade@home.com> wrote in message news:G3o9HE.KBB@lugnet.com... (...) 10 (...) moving (...) twin (...) The twin on Earth will be (much) older than the twin who boarded the spacecraft. Assuming the twin on Earth and the twin (...) (24 years ago, 7-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| (...) Everything in science is a theory. But Relativity is a working theory -- its various effects (time dilation, etc.) have actually been proven with high-speed jets, atomic clocks, and so on. Paul Davidson (24 years ago, 8-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| (...) Right. The theory of *gravity* is just a theory. (24 years ago, 8-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| (...) 8^) Certainly, but one of the two parties is moving relative to the inertial reference frame and one is not. Am I correct in thinking that the occupant of the ship will experience Doppler Shift of light while the "stationary" observer will (...) (24 years ago, 8-Nov-00, to lugnet.off-topic.geek)
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| (...) Yeah, everyone is moving, but the important thing is how people are moving in relation to each other. That's why it's called the theory of Relativity. Adrian -- www.brickfrenzy.com (24 years ago, 8-Nov-00, to lugnet.off-topic.geek)
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| (...) Does this mean once a person is travelling at a particular velocity (e.g. .99c), he will not feel any further time dilation effects if he is no longer accelerating? IOW, is time dilation only experienced during acceleration? Jude (24 years ago, 8-Nov-00, to lugnet.off-topic.geek)
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| (...) Um, actually, it's the Law of Gravity. It's been proven (at least the basic aspects) over and over enough times that you can accept it as a Law. "I know this defies the Law of Gravity...but I never studied law" -Bugs Bunny -Sean The Wascally (...) (24 years ago, 8-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| (...) The actual slowing takes place during acceleration, but it will persist at the slowed rate once acceleration ceases, lasting until the traveler drops back into the other (apparently stationary) inertial frame. Dave! (24 years ago, 8-Nov-00, to lugnet.off-topic.geek)
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| (...) Maybe. I don't understand it well enough. Lemme think about the headlights thing.... For someone standing on earth, light is moving away at about 300,000km/sec. Then, say we have a spaceship, moving at half the speed of light relative to (...) (24 years ago, 8-Nov-00, to lugnet.off-topic.geek)
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| Just looked this up in Britannica Online. (Search for "time dilation"). Acceleration definitely plays into it. *All* clocks in non-accelerating motion relative to an observer run slow by his/her frame of reference. (Thus potentially causing (...) (24 years ago, 8-Nov-00, to lugnet.off-topic.geek)
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| (...) Not quite sure what you mean by "inertial" and "noninertial," since as you point out previously *everyone* is moving. However, within a local inertial frame the Doppler shift of light can be identified to be of a particular character (I don't (...) (24 years ago, 8-Nov-00, to lugnet.off-topic.geek)
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| (...) However, some are moving in a certain way as to make it indistuigishable as to who is moving. i.e. me moving away from the universe is equivalent to universe moving away from me. (...) The equations are equivalent no matter what inertia frame (...) (24 years ago, 8-Nov-00, to lugnet.off-topic.geek)
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| (...) Well, thanks for throwing a monkey wrench into it for me. How do the famous de-synchronized clocks fit into this? Obviously one of them slowed down relative to the other. Do we infer that the ground-based clock decelerated sufficiently to (...) (24 years ago, 8-Nov-00, to lugnet.off-topic.geek)
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| (...) Yeah, that's what I don't get, as well. The terms "inertial" and "noninertial" come from the britannica article, and they mean "non-accelerating motion" and "accelerating motion". But I'm not sure how to tell which is which without an absolute (...) (24 years ago, 8-Nov-00, to lugnet.off-topic.geek)
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| (...) acceleration _is_ absolute - you can measure it, you can tell when your speed is constant. you _cannot_ tell what that speed really is though. not without a point of reference. (...) if the earth started accelerating, everyone and everything (...) (24 years ago, 8-Nov-00, to lugnet.off-topic.geek)
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| (...) observer (...) Acceleration is bad ju-ju, since it isn't accounted for in special relativity. It's only in General Relativity that we get gravity thrown into the mix, and that's taught in grad school. However, from a strictly special (...) (24 years ago, 8-Nov-00, to lugnet.off-topic.geek)
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| (...) Ahh. Ok, that makes me feel better about things. :) (...) Yes, that makes much sense. (24 years ago, 8-Nov-00, to lugnet.off-topic.geek)
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| (...) basic (...) The only Law of Gravity is that it exists. Many *theories* of gravity of been used to explain it, Relativity being one of the most recent (prior to that, Isaac Newton's was used). Paul Davidson (24 years ago, 9-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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| Paul Davidson <tinman@direct.ca> wrote in message news:G3qGAn.LCs@lugnet.com... (...) That is a misleading statement. General relativity explains and reliably *predicts* the observed behavior of matter far better than anything that came before it. (...) (24 years ago, 10-Nov-00, to lugnet.off-topic.geek, lugnet.space)
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