Simultaneous events and Einstein's absolute time
in [Relativity]
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From: PD on 3 Feb 2010 20:09 On Feb 3, 12:39 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 3 Feb, 17:03, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 2, 9:31 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 2 Feb, 19:07, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 2, 10:51 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > On 2 Feb, 13:15, Igor <thoov...(a)excite.com> wrote: > > > > > > > On Feb 1, 10:29 pm, artful <artful...(a)hotmail.com> wrote: > > > > > > > > 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 > > > > > > > And sound requires a medium. > > > > > > And light requires a medium - we call it "empty space". > > > > > And if this is how you want to define "medium" -- anything that > > > > carries a transmission of any description -- then there is no > > > > argument. But once again, this is not the connotation that physicists > > > > had associated with "medium" when there was much fuss about whether > > > > light was carried in a medium. > > > > As far as I'm concerned, space is to light what air is to sound. > > > In a very simplified and overly vague sense, this is certainly true. > > The problem then comes in assuming that because the statement is true > > in the vague sense, then it is true in the detailed sense. This is, of > > course, where it breaks down. > > > The statement is similar to saying that mammals are just like > > reptiles. When asked to defend the statement, one could say "They are > > both vertebrates. They both are tetrapods." Those statements are > > undeniably true, and yet it is just as undeniably false that mammals > > are just like reptiles. > > I agree. There is a difference between recognising the common or > analogous properties of two things, and going too far and being unable > to see or accept any differences. > > The important thing here is simply that both light and sound have > finite propagation times, and if that finite propagation time is used > as the basis of saying that simultaneity is relative But that is not the basis at all. What is important for the relativity of simultaneity is that the speed of the signal is the same in all reference frames. This is true for light and not true for sound, and this is why the speed of sound provides no rationale for the relativity of simultaneity. You may be noticing a problem with blind guesswork on your part. > and there is no > absolute timeframe, then it seems to me that the finite speed of sound > provides the same basis for that hypothesis. > > The reason I compare the two however is because, in fact, the finite > speed of sound was *never* used as a basis for that argument, partly > because it is possible to see something before you hear it, and so > that is the necessary common sense proof that events *really do* > happen before they are heard with the ears. > > The problem with light is that, as yet, there is nothing that goes > faster, and so it's very difficult to employ evidence against the > reasoning that events happen no sooner than they are detected (which > is relative to perspective). > > However, I like to go around this by saying *let us suppose* that > there is something that goes faster than light, This can certainly be supposed. One would then ask whether such a thing would violate the known laws of physics. It turns out that there are causality implications. You may want to look up "tachyons". > and this once again > allows us to suppose that events happen in an absolute timeframe and > that events 'actually happen' at a time interval that is different > from when they are detected by way of light. > > As I believe you said on a previous occasion, "that is not science", > because it supposes a mechanism of transmitting information which does > not exist in the real world, No, I did not say that or imply it. > but it is my view that this dogmatic and > minimalist approach to science that is actually hindering progress, > because it locks people into thinking that "nothing happens until you > observe it", when in fact this was precisely the view that Einstein > strongly argued *against*.
From: Ste on 3 Feb 2010 20:46 On 4 Feb, 01:09, PD <thedraperfam...(a)gmail.com> wrote: > On Feb 3, 12:39 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > As far as I'm concerned, space is to light what air is to sound. > > > > In a very simplified and overly vague sense, this is certainly true. > > > The problem then comes in assuming that because the statement is true > > > in the vague sense, then it is true in the detailed sense. This is, of > > > course, where it breaks down. > > > > The statement is similar to saying that mammals are just like > > > reptiles. When asked to defend the statement, one could say "They are > > > both vertebrates. They both are tetrapods." Those statements are > > > undeniably true, and yet it is just as undeniably false that mammals > > > are just like reptiles. > > > I agree. There is a difference between recognising the common or > > analogous properties of two things, and going too far and being unable > > to see or accept any differences. > > > The important thing here is simply that both light and sound have > > finite propagation times, and if that finite propagation time is used > > as the basis of saying that simultaneity is relative > > But that is not the basis at all. > What is important for the relativity of simultaneity is that the speed > of the signal is the same in all reference frames. This is true for > light and not true for sound, and this is why the speed of sound > provides no rationale for the relativity of simultaneity. > You may be noticing a problem with blind guesswork on your part. Do you have any experimental evidence for the contention that the speed of light as measured is the same in all reference frames and in all directions?
From: artful on 3 Feb 2010 20:59 On Feb 4, 11:55 am, Ste <ste_ro...(a)hotmail.com> wrote: > On 3 Feb, 22:25, artful <artful...(a)hotmail.com> wrote: > > > > > > > On Feb 4, 5:39 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > The important thing here is simply that both light and sound have > > > finite propagation times, and if that finite propagation time is used > > > as the basis of saying that simultaneity is relative > > > That is not the basis > > > > and there is no > > > absolute timeframe, then it seems to me that the finite speed of sound > > > provides the same basis for that hypothesis. > > > No .. because the speed being finite is not the basis > > > > The reason I compare the two however is because, in fact, the finite > > > speed of sound was *never* used as a basis for that argument, partly > > > because it is possible to see something before you hear it, and so > > > that is the necessary common sense proof that events *really do* > > > happen before they are heard with the ears. > > > No .. nothing to do with that at all > > > > The problem with light is that, as yet, there is nothing that goes > > > faster, and so it's very difficult to employ evidence against the > > > reasoning that events happen no sooner than they are detected (which > > > is relative to perspective). > > > You are confused about what RoS means. It is not (just) about visual > > appearance. > > > > However, I like to go around this by saying *let us suppose* that > > > there is something that goes faster than light, and this once again > > > allows us to suppose that events happen in an absolute timeframe > > > It wouldn't > > > > and > > > that events 'actually happen' at a time interval that is different > > > from when they are detected by way of light. > > > It has nothing to do with detecting with light > > > > As I believe you said on a previous occasion, "that is not science", > > > because it supposes a mechanism of transmitting information which does > > > not exist in the real world, but it is my view that this dogmatic and > > > minimalist approach to science that is actually hindering progress, > > > because it locks people into thinking that "nothing happens until you > > > observe it", when in fact this was precisely the view that Einstein > > > strongly argued *against*. > > > its not that its not science .. its that you have no idea what you are > > talking about and it is unrelated to the physics of SR > > Ian Paisley's shown his face in another guise again: "No, no, no, > no..." Perhaps you should stop saying so many things that are wrong. If you understood the subject about which you were posting at such length, you wouldn't waste so much of it with the nonsense that is incorrect. Especially s what you have said has already been explained to you as wrong. Its just a monumental waste of time on your behalf. Now .. if you are wanting to learn, now that you know what aspects of what you have said are wrong, then perhaps you should begin be looking the correct statements .. or asking what is correct.
From: artful on 3 Feb 2010 21:04 On Feb 3, 3:06 am, Jerry <Cephalobus_alie...(a)comcast.net> wrote: > On Feb 1, 5:44 pm, 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. > > You are confused by a serious PUN. > > There exists a demonstrable maximum possible speed of > communications, designated "c". This constant "c" is a fundamental > parameter in the specification of the geometric properties of > spacetime. Since this constant "c" is finite, absolute time does > not exist, assuming that our universe is correctly described by > this geometric model. To STE: Please note that it is not just the finiteness (as you were implying) .. but ALSO that it is a (universal) CONSTANT that has the consequent that time is absolute. Light could travel with a finite speed (but not a universally constant one) as it does in (say) emission theory, and that would be compatible with absolute time. The same is so for naive ether theories, where the speed is finite, but not the same in all frames of reference. However, those theories do not correctly model reality (ie they are not valid models). Do you see the difference?
From: PD on 3 Feb 2010 21:39
On Feb 3, 7:46 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 4 Feb, 01:09, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 3, 12:39 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > As far as I'm concerned, space is to light what air is to sound. > > > > > In a very simplified and overly vague sense, this is certainly true.. > > > > The problem then comes in assuming that because the statement is true > > > > in the vague sense, then it is true in the detailed sense. This is, of > > > > course, where it breaks down. > > > > > The statement is similar to saying that mammals are just like > > > > reptiles. When asked to defend the statement, one could say "They are > > > > both vertebrates. They both are tetrapods." Those statements are > > > > undeniably true, and yet it is just as undeniably false that mammals > > > > are just like reptiles. > > > > I agree. There is a difference between recognising the common or > > > analogous properties of two things, and going too far and being unable > > > to see or accept any differences. > > > > The important thing here is simply that both light and sound have > > > finite propagation times, and if that finite propagation time is used > > > as the basis of saying that simultaneity is relative > > > But that is not the basis at all. > > What is important for the relativity of simultaneity is that the speed > > of the signal is the same in all reference frames. This is true for > > light and not true for sound, and this is why the speed of sound > > provides no rationale for the relativity of simultaneity. > > You may be noticing a problem with blind guesswork on your part. > > Do you have any experimental evidence for the contention that the > speed of light as measured is the same in all reference frames and in > all directions? Absolutely. http://www.math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html You'll find that this contains a listing of a good number (though certainly nowhere near exhaustive) of published papers on experimental evidence of the above. |