The real twin paradox.
in [Relativity]
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From: Sue... on 27 Nov 2007 12:55 On Nov 27, 11:51 am, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > Sue... says... > > > > >On Nov 26, 4:22 pm, stevendaryl3...(a)yahoo.com (Daryl McCullough) > >wrote: > >> However, > >> a precise enough clock (atomic clock, for instance) > >> would notice a difference. If you left one atomic > >> clock at Big Ben, and carried the other one with > >> you to New York, then when you get back to Big Ben, > >> there will be differences in the elapsed times on > >> the two atomic clocks. > > >There were no clocks in motion. The proper time intervals > >were taken from views of the clocks that never left > >their stations in London and New York. > > You are making no sense whatsoever. Proper time is time > along a spacetime path. It has nothing to do with "views > of clocks". <<A clock in a moving frame will be seen to be running slow, or "dilated" according to the Lorentz transformation. The time will always be shortest as measured in its rest frame. The time measured in the frame in which the clock is at rest is called the "proper time". >> http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/tdil.html 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? Sue... http://en.wikipedia.org/wiki/Proper_time > > -- > Daryl McCullough > Ithaca, NY
From: colp on 27 Nov 2007 13:14 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. > 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.
From: colp on 27 Nov 2007 13:34 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, http://en.wikipedia.org/wiki/Time_dilation
From: colp on 27 Nov 2007 14:03 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.
From: colp on 27 Nov 2007 14:08
On Nov 28, 4:32 am, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > colp says... > > > > >On Nov 27, 9:51 am, stevendaryl3...(a)yahoo.com (Daryl McCullough) > >wrote: > >> SR doesn't say *anything* about the frame of reference of an > >> accelerated twin. It only talks about how things work within > >> a single inertial coordinate system. If the twins are accelerating, > >> then they are not in an inertial coordinate system. > > >The original thought experiment that I described in the OP (that Dirk > >quoted) does talk about inertial coordinate systems. What happened when > >the twins are accelerating and decellerating doesn't affect the > >paradox. > > Well, that's completely incorrect. Why is that? > You only think that because you haven't actually done a calculation. Wrong. The calculation is not relevant to the argument. |