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
