2002-6-14 Here is the results of a Google search on Time dilation and Twin paradox.
http://www.google.com/search?q=%22time+dilation%22+%22twin+paradox%22&site=s wr&hl=en&lr=&ie=UTF8&oe=UTF8 So far, of the ones I read, they all seem to agree as you said, that the effects are independent of direction. The twin paradox was raised in an attempt to use symmetry and time dilation to show that Special Relativity was inconsistent. Here is the paradox: Jane travels in a straight line at a relativistic speed v to some distant location. She then decelerates and returns. Her twin brother Joe stays at home on Earth. Joe observes that Jane's on-board clocks (including her biological one), which run at Jane's proper time, run slowly on both outbound and return leg. He therefore concludes that she will be younger than he will be when she returns. On the outward leg Jane observes Joe's clock to run slowly, and she observes that it ticks slowly on the return run. So will Jane conclude that Joe will have aged less? And if she does, who is correct? According to the proponents of the paradox, there is a symmetry between the two observers, so, using relativity, each will predict that the other is younger. This cannot be simultaneously true for both so, if the argument is correct, relativity is wrong. From: http://www.phys.unsw.edu.au/~jw/twin.html ----- Original Message ----- From: "Joseph B. Reid" <[EMAIL PROTECTED]> To: "U.S. Metric Association" <[EMAIL PROTECTED]> Sent: Friday, 2002-06-14 14:28 Subject: [USMA:20401] Re: Fwd: Re: Yesterday's Star Trek on BBC 2 > I think that Bill Potts in USMA 20399 has made the wrong assumption that A > is stationary and that B is moving. That is contrary to the basic > postulate of relativity that there is no such condition as stationary; > there is only motion relative to each other. > > >John: > > > >I believe you have that one wrong. The slowing of the local clock as one > >approaches the speed of light is independent of the direction of travel. > > > >The only problem with respect to the twins is that a really enormous amount > >of energy would be required to carry out the experiment. However, the > >traveling twin would indeed be younger than the stay-at-home one. > > > >The twin traveling close to the speed of light would not, of course, be > >aware of the slowing of the clock. That slowing is only as "viewed" from a > >stationary vantage point. > > > >Bill Potts, CMS > >Roseville, CA > >http://metric1.org [SI Navigator] > > > >> -----Original Message----- > >> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On > >> Behalf Of kilopascal > >> Sent: Thursday, June 13, 2002 21:03 > >> To: U.S. Metric Association > >> Subject: [USMA:20398] Re: Fwd: Re: Yesterday's Startrek on BBC 2 > >> > >> > >> 2002-06-13 > >> > >> This reminds me of the common belief that if out of a pair of > >> twins, one who > >> travels in space and another who remains on earth, the returning traveller > >> will find his twin who remained behind older looking. This is > >> known as the > >> twin paradox. But, as we know, nature abhors paradoxes, so the way the > >> SCI-FI writers have presented it is wrong. > >> > >> As Joe pointed out, the observer (Twin remaining on Earth) (A) > >> will observe > >> his twin in space (B) ageing less as his clock is running slower > >> as he moves > >> away at the speed of light. The common belief is that when B returns to > >> Earth, he is noticeably younger. The truth is, that as the ship turns > >> around and moves back towards the earth at the speed of light, > >> the opposite > >> occurs. B's clock now appears to move faster than on earth and B's age > >> catches up to that of A on the Earth. When B steps off the ship, > >> he is the > >> same age as his brother. The only difference will be the normal > >> ageing that > >> took place because the trip would have consumed some time. Thus time is > >> conserved and nature remains in balance. > >> > >> John > >> > >> > >> > >> > >> > >> > >> ----- Original Message ----- > >> From: "Joseph B. Reid" <[EMAIL PROTECTED]> > >> To: "U.S. Metric Association" <[EMAIL PROTECTED]> > >> Sent: Thursday, 2002-06-13 20:57 > >> Subject: [USMA:20396] Re: Fwd: Re: Yesterday's Startrek on BBC 2 > >> > >> > >> > Madan wrote in USMA 20395: > >> > > >> > >Few months back, I had an argument with my friend > >> > >about the time travel and back to the future concept. > >> > > > >> > >He said that we will be in same time, if we travel > >> > >in the speed of light. > >> > >My argument is this > >> > >1. even if our spaceship is to move a few meters, > >> > > it is going to take atleast few picoseconds. > >> > >2. its going to take few minutes to make a sandwich. > >> > > > >> > >The duration taken to do something is called time. > >> > > > >> > >Is the concept of 'time' a real thing like distance, > >> > >electricity, etc or just a virtual thing. > >> > > > >> > >Madan > >> > > >> > > >> > As long as we stay on earth there is no problem. Two persons > >> at the same > >> > place can set their clocks to agree. It is when they try to compare the > >> > time when they are moving apart that things get complicated. Michelson > >> and > >> > Morley tried to find the speed by which we are moving through > >> the ether in > >> > which light waves travel. They failed. Einstein theorized > >> that if A and > >> B > >> > are moving apart at high speed, A will observe that B's > >> surroundings have > >> > shrunk and his clock seems to be running slow to compensate and > >> thus keep > >> > the apparent speed of light around B constant. At the same time, B > >> > observes that A's surroundings have shrunk and A's clock is > >> running slow. > >> > Hence the relativity or reciprocity of the situation. If C is midway > >> > between A and B, he will observe that A's clock and B's clock are > >> > synchronized. > >> > > >> > Joseph B.Reid > >> > 17 Glebe Road West > >> > Toronto M5P 1C8 Tel. 416 486-6071 > >> > > >> > > >> > > Joseph B.Reid > 17 Glebe Road West > Toronto M5P 1C8 Tel. 416 486-6071 >
