The real twin paradox.
in [Relativity]
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From: colp on 27 Nov 2007 18:03 On Nov 28, 8:40 am, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > In article <6ed33a22-9b96-4304-967b-7e1b359c0...(a)d27g2000prf.googlegroups.com>, > colp says... > > > > > > >On Nov 28, 4:24 am, stevendaryl3...(a)yahoo.com (Daryl McCullough) > >wrote: > >> colp says... > > >> >Because an observer on the ground sees the satellites in motion > >> >relative to them, Special Relativity predicts that we should see their > >> >clocks ticking more slowly (see the Special Relativity lecture). > > >> You don't know what you are talking about. Relativity > >> is not about what this or that observer *sees*. > > >I was quoting the the following page: > >http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html > > >So what you are saying is that Ohio State university does not know > >what it is talking about. > > Do you know the difference between a mathematical *derivation* > and a pop science description? A mathemaitcal derivation is an abstract symbolic represenatation of the relationships which are the essence of the idea, while a pop science desciption is an interpretation of the idea in common language. "Special relativity predicts that we should see their clocks ticking more slowly" is a correct description of GPS sattelites, if we separate GR & SR effects. > That page is *not* a rigorous > derivation, it's a layman's introduction to the subject. You > can't deduce anything about the consistency of relativity from > a popular science article. Yes you can, so long as the article accurately represents the original ideas. > > It's as if you tried to solve some mystery about the life of > Julius Caesar by studying a picture book about him written > for eight-year olds. Straw man.
From: colp on 27 Nov 2007 18:29 > And while he uses as reference the wiki page on time dilation (http:// > en.wikipedia.org/wiki/Time_dilation), the following page in the same > wiki (http://en.wikipedia.org/wiki/Twin_paradox) explains in detail > the twin paradox You are supporting my original argument by quoting that page. The specific example on that page uses the same formula and methodology as I used when I showed Dirk's error in the OP. The specific example only uses the Lorentz factor for calculating time dilation of the travelling twin. It makes no distinction between the outbound and return legs, as oppoed to Dirk who treats the two legs differently.
From: bz on 27 Nov 2007 16:41 colp <colp(a)solder.ath.cx> wrote in news:65ada6bc-78dc-4c10-a9e7-fb28f87d0983(a)i12g2000prf.googlegroups.com: > On Nov 27, 11:49 pm, bz <bz+...(a)ch100-5.chem.lsu.edu> wrote: >> colp <c...(a)solder.ath.cx> wrote >> innews:c3ae81ae-9ac0-4842-afb0-78ddd999b1bc(a)s6g2000prc.googlegroups.com: > <snip> >> >> He said [quote] >> >> Then gamma = 1/square-root(1-(4/5)^2) = 1/square-root(9/25) = 5/3. >> >> [unquote] >> >> So, he is using exactly the formula you asked about. >> >> > Yes, gamma is 5/3 for v = 4/5 c using my formula. >> >> >> now if you take velocity away from ... as positive and toward ... as >> >> negative, your other great mystery will be cleared up. >> >> > Oh really? >> >> Really. > > If you think that the mystery is cleared up, then why is it necessary > to use t' = gamma (t - vx/c^2) to calculate time dilation? > > According to Wikipedia: > > delta t = gamma delta t0 > > Where delta t0 is the time interval between two colocal events (i.e. > happening at the same place) for an observer in some inertial frame > (e.g. ticks on his clock), > and delta t is the time interval between those same events, as > measured by another observer, inertially moving with velocity v with > respect to the former observer, They expect you to understand that the Delta T (CHANGE in T) must be added sometimes and subtracted sometimes, depending on whether you are closing with the source or going away from it. Notice that they say [quote] Delta_t_0 is the time interval between two colocal events (i.e. happening at the same place) for an observer in some inertial frame (e.g. ticks on his clock), Delta t, is the time interval between those same events, as measured by another observer, inertially moving with velocity v with respect to the former observer, v, is the relative velocity between the observer and the moving clock [unquote] velocity. Not speed. Speed has no direction. velocity does. > http://en.wikipedia.org/wiki/Time_dilation > -- bz please pardon my infinite ignorance, the set-of-things-I-do-not-know is an infinite set. bz+nanae(a)ch100-5.chem.lsu.edu
From: Sue... on 27 Nov 2007 22:39 On Nov 27, 1:35 pm, bz <bz+...(a)ch100-5.chem.lsu.edu> wrote: > "Sue..." <suzysewns...(a)yahoo.com.au> wrote innews:e35a303c-4fce-4358-a6c7-3aac59e49677(a)b40g2000prf.googlegroups.com: > > > Does that mean that when I saw Big-Ben moving away from me > > I could have calculted its proper time and my > > egg would have been perfect, instead of overdone? > > If you have left someone in London and you tell them, from your ship that > is moving near c, when you want them to start boiling and stop boiling the > eggs, you better apply the right corrections, or the eggs won't be done > when you get home. I didn't know you went for balut. Actually it is London that is moving. My ship is stationary. But that may offer opportunty to better explain why I use two *types* of clocks. With colp's scenario my atomic clocks only slow as a result of earth's gravity. The Fizeau moving media light clocks only slow as a result of free-space dielectric moving between the mirrors. If your formula doesn't agree with one clock, then pick another. There are four to choose from. (Two clocks on the massive planet at mid point are not included but could be) It is not likely to be popular with the sci-fi fans because the presence of two clock types makes it difficult to argue that a cooking egg or a dividing cell could know which type to look at. The PoR says they will look at the atomic clocks because rain does not take longer to reach the ground simply because it is viewed as a longer diagonal path from a moving car. Sue... In the subatomic realm, all bets are off because 377 ohm media only exist when something radiates. (or is it the other way 'round? I think Feynman says it is both ways. http://en.wikipedia.org/wiki/Path_integral_formulation > > -- > bz >
From: harry on 28 Nov 2007 04:40
"colp" <colp(a)solder.ath.cx> wrote in message news:a32da81e-30d8-4242-811e-d233128dfc71(a)s36g2000prg.googlegroups.com... > On Nov 27, 9:55 pm, "harry" <harald.vanlintelButNotT...(a)epfl.ch> > wrote: >> "colp" <c...(a)solder.ath.cx> wrote in message >> >> news:3f691012-f547-4146-8a75-b3796fcc60f9(a)s8g2000prg.googlegroups.com... >> >> >> >> > On Nov 27, 1:05 am, "harry" <harald.vanlintelButNotT...(a)epfl.ch> >> > wrote: >> >> One last attempt ... >> >> >> "colp" <c...(a)solder.ath.cx> wrote in message >> >> >>news:81a29c49-6048-4f2d-87fd-b59380b5dd98(a)b40g2000prf.googlegroups.com... >> >> >> > On Nov 25, 5:54 am, stevendaryl3...(a)yahoo.com (Daryl McCullough) >> >> > wrote: >> >> >> colp says... >> >> >> >> >The point is that a paradox exists due to the time dilation >> >> >> >expected >> >> >> >by SR. >> >> >> >> No, there is no paradox in the sense of contradiction. >> >> >> > The contradiction between SR prediction ant reality is described >> >> > below: >> >> >> > This thought experiment is like the classic twin paradox, but in >> >> > this >> >> > experiment both twins leave earth and travel symmetric return trips >> >> > in >> >> > opposite directions. >> >> >> > Since the paths taken by the twins in this experiment are symmetric, >> >> > they must be the same age when they meet on their return to earth. >> >> > In this experiment the twins maintain constant observation of each >> >> > other's clocks, from when they depart until they return and find >> >> > that >> >> > their clocks tell the same time. >> >> >> Sure. >> >> >> > Special relativity says that each twin must observe that the other's >> >> > clock is running slow, and at no time does special relativity allow >> >> > for an observation which shows that the other clock is running fast. >> >> >> There is no need for that, and this has been explained to you from the >> >> very >> >> start. >> >> > What has been explained from the very start? >> >> That there is no need for an observation that "shows that the other clock >> is >> running fast". > > The fact that SR pedicts that such an observation can be made is part > of the paradox. Ignoring the observation means ignoring the paradox. No, SRT doesn't really predict such an observation, see below. >> And you overlooked the illustration that I prepared specially >> for you: > > I read it, but I could not see the point that you were trying to make. It's a similar paradox, about a "lacking" observation that is based on a misunderstanding. Understand that one and you will understand your own paradox. Harald |