A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: Peter Webb on 4 Mar 2010 05:36 >> I'm not denying it. I'm saying experiments that involve acceleration >> are the realm of GR (as I understand it), and that acceleration is the >> cause of "real" time dilation. We're talking about SR, and therefore >> we cannot be talking about any experiment that involves acceleration. >> >> ________________________________ >> It is true that you cannot devise an experiment whereby two clocks are >> together and then separated without at least one of them experiencing >> acceleration at some point; that unfortunately is a mathematical fact, >> not a physical one. > > No .. you can do that without acceleration. But it involves multiple > clocks. > > Well, I put it to you that acceleration is the second derivative of position ..... There is one way you can get close. You could have clock circling the earth in a plane, and flying past some reference clock fixed to the earth, and compare times when they are close. Unfortunately though it could be argued correctly that the flying clock is actually accelerated more, because it circles the earth faster, effectively the additional centrifugal force reduces the measured force of g in the plane, and I suspect that the nett effect is the opposite to that predicted by SR - a very slight increase in the rate at which time passes. I could be wrong. However, I stress that these effects of GR are typically many orders of magnitude lower than those from SR, and it is obviously very hard to design experiments which even show the GR effects, the SR ones are so dominant, and now a standard part of engineering. I am sure you are aware that GPS satellites have to compensate for both SR and GR. It is interesting though that these are for vastly different reasons. SR causes the effects you would expect on the accuracy of the clocks, but GR's effect is mostly not through time dilation but rather through directly affecting the orbit of the satellite.
From: Ste on 4 Mar 2010 05:41 On 4 Mar, 02:14, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > >> > If you had, > >> > you'd also have found out that *creationists* (who you've oddly chosen > >> > to commandeer in your support) also make this argument, and yet Popper > >> > later recanted this criticism. In fact I seem to remember that the > >> > page I linked to on talk.origins also mentioned this. And yet you > >> > claim to know all about evolution and all about the arguments of > >> > creationists. > > >> Let me get this straight. You seem to think that you had some evidence > >> which > >> was linked to page published on anewsgroup I don't subscribe to ... > > > I gave you the bloody link the other day Peter. And I've given it > > again at the top of this post. > > It does not address the tests of falsifiability of evolution that I gave. > And the link you provided is not to Lakatos, its just some random person. This is the only point worth responding to. The link was not to Lakatos. It was a link to a page which talked about Popper's criticism of Darwin. You complained that you didn't believe me and didn't have access to the newsgroup, and I pointed out that the page was not on a newsgroup, it was a web page, the link to which I've repeatedly posted.
From: Peter Webb on 4 Mar 2010 05:50 SR specifically predicts that if one twin travels away at high speed and returns, they will have aged less than the stay at home twin. This prediction of SR is completely independent of any subsequent predictions of GR concerning time dilation due to acceleration, which in any event is even more negligible. It is a direct consequence of time dilation. You said you believed SR. Do you believe that as a result of the time dilation predicted by SR that if one twin traveled away from earth at 0.9c for a year, bounced of some disant trampoline and returned to the earth for another year, the twin on the rocket will have aged less due to the time dilation predicted by SR? If you do not, then you do not believe SR. If you do, explain how the fact that one twin is older is due to "propogation delays". Do you even know what you believe? *Inability to learn*
From: Ste on 4 Mar 2010 05:54 On 4 Mar, 09:39, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > news:8984b4b4-92e9-466a-ad51-20e6b4e815bc(a)u9g2000yqb.googlegroups.com... > On 3 Mar, 22:23, "Inertial" <relativ...(a)rest.com> wrote: > > > > > > > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > >news:64d02f70-01e4-44a5-a5ab-41429bf37f71(a)q15g2000yqj.googlegroups.com... > > > > I'm sure I said something about the ludicrous assertions that some > > > people here have made about the conceptual basis of SR. That is, > > > assertions that verge on meaningless, like "rotation into time" as an > > > explanation for length contraction. Or even observed time dilation (in > > > SR) being "real" as opposed to merely a function of propagation > > > delays. But none of this fundamentally challenges SR. > > > Time dilation isn't anything to do with propagation delays .. they do NOT > > cause time dilation. It IS real in that it has been measured > > experimentally. > > > Your denial of reality is another trademark of a crackpot. > > I'm not denying it. I'm saying experiments that involve acceleration > are the realm of GR (as I understand it), and that acceleration is the > cause of "real" time dilation. We're talking about SR, and therefore > we cannot be talking about any experiment that involves acceleration. > > ________________________________ > It is true that you cannot devise an experiment whereby two clocks are > together and then separated without at least one of them experiencing > acceleration at some point; that unfortunately is a mathematical fact, not a > physical one. No, it is a physical fact. > However, you can make the contribution of acceleration "vanishingly small", > by designing thought experiments where the accelerations are very low and > slow. Sending a rocket to another star is one such example. Not really, because if the total acceleration is small, then so is the speed. > You now appear to be claiming that you *don't* believe the twins will be > different ages due to simple time dilation in SR, which means you *don't* > agree that SR is correct. > > So, yet again, like the uber-crank you are, you have completely changed your > story. > > Yesterday you believed in the predictions of SR. Now you say you don't. > > Its called *inability to learn*. <yawn>
From: Jerry on 4 Mar 2010 07:15
On Mar 4, 2:12 am, Ste <ste_ro...(a)hotmail.com> wrote: > I pay attention. It's just that I've been asking for weeks for an > explanation for this assertion that time slows down in SR above and > beyond the "apparent" effect due to propagation delays, and all I keep > getting in return is a bald assertion that this is the case, even > though I've made it quite clear that I do not find this bald assertion > believable. This has been brought up to you before, but you have -not- paid attention. Consider muons traveling at high speed in a circular path, as for instance in the g-2 experiment. The measured lifespan of muons in this scenario is much greater than that of stationary muons. This effect is consistent with relativistic predictions. Yet the "average" propagation delay that exists between an observer standing beside the ring and the circulating muons must be zero. Jerry |