Simultaneous events and Einstein's absolute time
in [Relativity]
|
From: Androcles on 1 Feb 2010 07:44 "Paul B. Andersen" <paul.b.andersen(a)somewhere.no> wrote in message news:hk6f58$1v4f$1(a)news01.tp.hist.no... > Good grief! :-) > > I and my wife are two persons who eat dinner once a day. > My wife and I are synchronized so that the events "she eats dinner" > and "I eat dinner" occur at the same time and place. The simple question > is, are these simultaneous events per Einstein's theory? > > If I tell you that I started eating dinner three years before my wife, > do you now say dinner eaten by my wife an me are no longer > simultaneous events, and do you now agree that there was insufficient > information to determine the answer to the simple question above? > Did she go shopping at Alpha Centauri and eat fewer dinners than you while she was gone? Did she email you as many birthday cards as you emailed to her? Just think, you've saved money on taking her to dinner, according to Einstein's theory. She can buy herself new shoes with it, but according to Newton you are heading for a divorce for missing her birthday. Had she been counting the Earth's revolutions for her clock she'd be calling you cheapskate idiot -- and be right. Then we'd see how good your grief is.
From: PD on 1 Feb 2010 13:27 On Jan 31, 8:47 am, DSeppala <dsepp...(a)austin.rr.com> wrote: > In his theory of relativity, Einstein includes implicit use of > absolute time. This makes his notion of simultaneous events undefined > for many scenarios. Here's a simple example that demonstrates the > problem. > > Let there be two identical devices that emit a pulse once a second. > I'll call these devices PL1 and PL2. Let these two devices have zero > relative velocity, and be at the same coordinate on the x-axis, and be > synchronized such that they each emit pulses at the same time. > The simple question is, each time they emit a pulse are these > simultaneous events per Einstein's theory? I presume most will say > yes. But with Einstein's theory, the answer is indeterminate. There > is not enough information given to answer that question. > For those who think that answer is wrong we add a third identical > device along the x-axis to the right of PL1 and PL2. I'll call this > device PR1. Now let there be an inertial frame moving along the x- > axis relative to these devices. Let this frame turn on PL1 and PR1 > simultaneously and let the velocity and distances be such that these > simultaneous events in the moving frame occur one second apart in the > rest frame of these devices. Now per Einstein, when each pulse is > generated from PL1 and PR1 the moving frame observer says these events > occur simultaneously. Do the rest frame observers say these events > occur simultaneously? I presume most in this group would say no. > Those events are not simultaneous, they occur one second apart as > measured in the rest frame. They are simultaneous in the moving frame and not simultaneous in the pulsers' rest frame. What's the problem? > If anyone thinks that is the correct answer, we go back to our > original two devices PL1 and PL2. If I tell you PL2 was turned on and > started emitting pulses one second after PL1 started emitting pulses, One second after PL1 in which frame? > do you now say pulses emitted from PL1 and PL2 are no longer > simultaneous events, as you did for PL1 and PR1? And do you now > agree that there was insufficient information to determine the answer > to the first question in this posting? No. > Einstein in his theory of relativity actually implicitly > includes a notion of absolute time in each problem, and there seems to > be an implicity redefinition of that in problems like the twins > problem and other problems. > David Seppala > Bastrop TX
From: Igor on 1 Feb 2010 13:27 On Jan 31, 9:47 am, DSeppala <dsepp...(a)austin.rr.com> wrote: > In his theory of relativity, Einstein includes implicit use of > absolute time. This makes his notion of simultaneous events undefined > for many scenarios. Here's a simple example that demonstrates the > problem. > > Let there be two identical devices that emit a pulse once a second. > I'll call these devices PL1 and PL2. Let these two devices have zero > relative velocity, and be at the same coordinate on the x-axis, and be > synchronized such that they each emit pulses at the same time. > The simple question is, each time they emit a pulse are these > simultaneous events per Einstein's theory? I presume most will say > yes. But with Einstein's theory, the answer is indeterminate. There > is not enough information given to answer that question. > For those who think that answer is wrong we add a third identical > device along the x-axis to the right of PL1 and PL2. I'll call this > device PR1. Now let there be an inertial frame moving along the x- > axis relative to these devices. Let this frame turn on PL1 and PR1 > simultaneously and let the velocity and distances be such that these > simultaneous events in the moving frame occur one second apart in the > rest frame of these devices. Now per Einstein, when each pulse is > generated from PL1 and PR1 the moving frame observer says these events > occur simultaneously. Do the rest frame observers say these events > occur simultaneously? I presume most in this group would say no. > Those events are not simultaneous, they occur one second apart as > measured in the rest frame. > If anyone thinks that is the correct answer, we go back to our > original two devices PL1 and PL2. If I tell you PL2 was turned on and > started emitting pulses one second after PL1 started emitting pulses, > do you now say pulses emitted from PL1 and PL2 are no longer > simultaneous events, as you did for PL1 and PR1? And do you now > agree that there was insufficient information to determine the answer > to the first question in this posting? > Einstein in his theory of relativity actually implicitly > includes a notion of absolute time in each problem, and there seems to > be an implicity redefinition of that in problems like the twins > problem and other problems. > David Seppala > Bastrop TX Absolute time and a finite speed of light are contradictory concepts. Therefore, since it's easy to demonstrate that light has a finite speed, absolute time cannot exist.
From: Ste on 1 Feb 2010 18:44 On 1 Feb, 18:27, Igor <thoov...(a)excite.com> wrote: > > Absolute time and a finite speed of light are contradictory concepts. > Therefore, since it's easy to demonstrate that light has a finite > speed, absolute time cannot exist. The same arguments (whether true or not) can also be made from the existence of a finite speed of sound.
From: artful on 1 Feb 2010 22:29
On Feb 2, 10:44 am, Ste <ste_ro...(a)hotmail.com> wrote: > On 1 Feb, 18:27, Igor <thoov...(a)excite.com> wrote: > > > > > Absolute time and a finite speed of light are contradictory concepts. > > Therefore, since it's easy to demonstrate that light has a finite > > speed, absolute time cannot exist. > > The same arguments (whether true or not) can also be made from the > existence of a finite speed of sound. Nope .. because the speed of sound is frame dependant |