SR and a lightbulb
in [Relativity]
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From: Androcles on 9 Jan 2010 02:09 "Anti Vigilante" <antivigilante(a)pyrabang.com> wrote in message news:hi98gn$m0g$2(a)news.eternal-september.org... > On Fri, 08 Jan 2010 10:16:20 -0800, eric gisse wrote: > >> PD wrote: >> >>> On Jan 7, 3:42 pm, ..@..(Henry Wilson DSc) wrote: >>>> On Thu, 7 Jan 2010 12:55:33 -0800 (PST), PD >>>> <thedraperfam...(a)gmail.com> wrote: >>>> >>>> >I'll be a little more precise: At the instant when the motion of the >>>> >front of the pole stops as it hits the back wall of the barn, what >>>> >happens to the motion of the back of the pole? >>>> >>>> It stops instantly as well. Reality doesn't rely on what humans see. >>>> >>>> >>> I am SO happy that you gave this response. This gives me the chance to >>> ask you a few questions. >> [...] >> >> >>> 1. You claim that the back end stops instantly, but that this is a >>> reality we cannot see. If you cannot see it, how do you know that it >>> happens? What method of truth checking are you using to determine the >>> truth value of the claim that the back end stops instantly. (PLEASE >>> PLEASE PLEASE tell me that you rely on common sense for this.) >> [...] >> >>> 2. Since science uses observation to check the truth of claims, but you >>> believe that reality is not revealed by observation, is it your claim >>> that science is in general a waste of time, since that is not how >>> reality is determined? If so, then why diddle around on sci.*.*, if you >>> believe that the whole business of how science works is just bogus to >>> begin with? (PLEASE PLEASE PLEASE tell me that what you do is science >>> and what scientists do is not science.) >> >> Sorry Paul, but Henri has explained this one to me. >> >> "No, but they are so stupid I'm laughing my bloody head off at their >> posts. Haven't laughed so much in years." >> >> Henri knows he is not doing science, as Henri can't be bothered to do >> simple things like publish his work (which he has talked about doing for >> a decade) or make concrete, falsifiable predictions with his theory >> (which he wants me to do FOR HIM). But rather he enjoys the game of >> laughing at what people like you and me tell him, which is fine with me >> since that goes both ways. >> >> >>> 3. By what physical process does the back end of the rod become aware >>> that the front end of the rod has stopped, at the very instant that the >>> front end of the rod stops? What signal travels at infinite speed from >>> the front of the rod to the back of the rod to inform the back of the >>> rod that it should stop? And by what fundamental interaction does this >>> signal travel at infinite speed? (PLEASE PLEASE PLEASE tell me it's the >>> Wilson Infinite Communication Speed Interaction [WICSI] that you >>> believe that people should be investigating.) >> [...] > > It's worse. If c+v is possible In hypothetical sentences introduced by 'if' and referring to past time, where conditions are to be deemed 'unfulfilled', the verb will regularly be found in the pluperfect subjunctive, in both protasis and apodosis. -- Donet, "Principles of Elementary Latin Syntax"
From: train on 9 Jan 2010 09:38 On Jan 9, 5:08 am, "Inertial" <relativ...(a)rest.com> wrote: > "train" <gehan.ameresek...(a)gmail.com> wrote in message > > news:0e6f25f8-9184-43ca-9aa6-91a3da418ed6(a)e27g2000yqd.googlegroups.com... > > > > > > > On Jan 8, 5:49 am, "Inertial" <relativ...(a)rest.com> wrote: > >> "train" <gehan.ameresek...(a)gmail.com> wrote in message > > >>news:7c9ad0f4-b028-4949-9a3f-305fc195c68c(a)e37g2000yqn.googlegroups.com.... > > >> > On Jan 8, 4:13 am, eric gisse <jowr.pi.nos...(a)gmail.com> wrote: > >> >> ..@..(Henry Wilson DSc) wrote: > >> >> > On Thu, 7 Jan 2010 12:55:33 -0800 (PST), PD > >> >> > <thedraperfam...(a)gmail.com> > >> >> > wrote: > > >> >> >>On Jan 7, 2:41 pm, ..@..(Henry Wilson DSc) wrote: > >> >> >>> On Thu, 7 Jan 2010 06:54:28 -0800 (PST), PD > >> >> >>> <thedraperfam...(a)gmail.com> > >> >> >>> wrote: > >> >> >>> >On Jan 6, 6:29 pm, ..@..(Henry Wilson DSc) wrote: > > >> >> >>> >This has nothing to do with what humans see. This is a matter of > >> >> >>> >whether the barn door strikes the pole or not, which can be > >> >> >>> >recorded > >> >> >>> >with or without humans present. > > >> >> >>> >Now: At the time when the front of the pole hits the back wall of > >> >> >>> >the > >> >> >>> >barn, what happens to the back end of the pole AT THAT INSTANT? > > >> >> >>> At any particular instant...or if time diesn't even exist ...the > >> >> >>> two > >> >> >>> ends of the pole are separated by the same absolute spatial > >> >> >>> interval. > > >> >> >>I'll be a little more precise: At the instant when the motion of the > >> >> >>front of the pole stops as it hits the back wall of the barn, what > >> >> >>happens to the motion of the back of the pole? > > >> >> > It stops instantly as well. Reality doesn't rely on what humans see. > > >> >> Really? Instantly? > > >> >> [...] > > >> > We this is indeed the point. Can anything travel faster than light? > >> > When the pole hits the back of the barn door and stops instantly, > > >> Which means its a pretty tough barn door :) > > >> > the > >> > impact has to be transmitted through the pole atom by atom. Can this > >> > happen faster than the speed of light? In classical mechanics yes > > >> It usually happens at what is usually called the speed of sound for that > >> material .. the speed that such compression 'information' is transmitted > >> through the material. > > >> If this immovable barn door is trying to travel through the rod (from the > >> moment of collision) at faster than the speed of sound in that rod, it > >> will > >> cause catastrophic damage to the rod, as its back end tries to plough on > >> forwards and compress the rod faster than it can handle. > > >> This effect is the same in principle whether SR or classical mechanics.. > > >> > In SRT if you follow it, you will have two effects The instant the > >> > pole stops, > > >> You mean the instant the front end of it stops. In the pole frame, the > >> back > >> end is blissfully unaware that its front end has crashed into a > >> carelessly > >> closed barn door. > > >> > the length contraction disappears, atom by atom along the > >> > length of the pole > > >> Yes .. as those atoms get slowed down > > >> > at the speed of light. > > >> Well. it all depends on what happens to the various bits of the rod. Its > >> certainly not going to be good for it. Certainly the information (in SR) > >> cannot get to the back end of the rod FASTER than the speed of light. it > >> would probably get there at the maximum of the speed of sound in that > >> material, and the speed of the barn wrt the rod (ie either the > >> compression > >> wave thru the rod gets to the back of the rod first, or the barn door > >> itself > >> does :)) > > >> > as the stopping of the pole also takes place at the speed of light > >> > atom by atom. > >> > The pole will then pop right out of the front of the Barn Door. > > >> More likely it will compress and shatter under the stress. We're > >> assuming a > >> very strong barn door here. > > >> > All > >> > this for the farmer watching the pole fly through the barn door at > >> > close to the speed of light. > > >> Life is pretty dull on a farm .. you need al lthe entertainment you can > >> get. > > > Well well, so reality for the rod is now limited by the speed of > > sound. > > I did not say that. Just that the compression information cannot travel > thru the rod faster than that speed. OK > > However, the door itself can go smashing thru the rod faster than the speed, > destroying the rod along the way Destruction travelling faster than sound? > > > A fine pickle we have > > here. > > Do we want to do a pickle in the barn scenario now? Hold the pickle > > > Anyway Inertial you're cool. > > > What if the barn doors are electrified? Then will the speed of > > electricity pass through the rod faster than sound? > > Yes. Depending on what you mean by speed of electricity .. and whether the > rod is a conductor or not. Do you mean the speed of electon drift, or how > fast the em travels. Both are less than c .. and you could walk faster than > the electorn drife rate of a conductor EM of course. > > > But I digress. I would like to know what you think of the question - > > is the light bulb on > > only when you see it is on or before? It is important and relevant. > > Given that we have a definition of simultaneity, and we have a finite speed > for light, then we certainly can have a light being on before we see it (and > it being off when we do see it). 'Seeing it' is not the issue here. > > As a general question though, it does highlight what we think of as 'now' as > opposed to what is really 'now'. When you look at someone walking down the > street and say hello to them, you think you are talking to them as they are > now . .but you are actually seeing them as they were some time ago, and > hearing them from an even longer time ago. In reality, you are along in > your 'now' .. at ant given time, nothing event that exists at the same time > as you in the universe can have any effect on you at that time, and you > likewise you cannot have any effect on those events. Of course, events from > before then can have an effect on you .. and the events now can have an > effect on you later etc. To simply .. events that happen at 'close enough' > to the 'same time' but separated in space cannot have a cause and effect on > each other (the more technical and accurate relationship between such events > is saying that they are space-like separated)/ > > Back to the scenario that we have here .. the claim is that the light does > not come on at all in one frame but does in another .. which SR does not > claim, and which is absolute nonsense as frames are only references for > taking measurement of the same events. And event either happens or it does > not. I will let our jury here decide that one. However for the rest of your statements I say - exactly I agree. >but you are actually seeing them as they were some time ago, and > hearing them from an even longer time ago Yes yes but here is the clincher - can I know, by calculation, if I know the distance to the person who said hello at the time of his saying hello, the time in my frame at which he said hello and the time in his frame in which he said these words -and the direct linear relationship between those two times? There has to be. Please do not say the relationship is indeterminate. T However
From: dlzc on 9 Jan 2010 12:59 Dear Henry Wilson: On Jan 8, 10:15 pm, ..@..(Henry Wilson DSc) wrote: > On Fri, 8 Jan 2010 06:55:59 -0800 (PST),dlzc<dl...(a)cox.net> wrote: .... > >Remove the bulb, and replace it with an LED. > >Still no way to get the signal to flow as > >close to c as to be convincing. > > >If it lights, it lights for all frames. > > The contacts never meet in any frame except > that which sees them both moving away in > opposite directions at the same speed. Because light from the ends don't arrive at your eyes at the same instant, you think that means something important. If the circuit is closed long enough, the light lights for all frames. And SR allows you to calculate what all inertial observers will see, and more importantly, what the moving circuit "sees". > So the light flashes in that frame but is > not seen by any other observer because it > cannot happen in any other frame. > > Isn't SR great? It is pretty slick, and your Doctorate of Scatology degree isn't doing you any good. David A. Smith
From: eric gisse on 9 Jan 2010 15:40 Anti Vigilante wrote: [...] > It's worse. If c+v is possible then that front signal may reach the back > a long time after the front stops. This suggests that c+v has > relativistic features as well. Something that is quite interesting. Mh-hmm. This is the repeatedly mentioned 'bunching' that is not observed but repeatedly discussed. Henri 'escapes' this problem by babbling bullshit about extinction which manages to conspire to make everything look like relativity is true. > > >
From: Androcles on 9 Jan 2010 20:02
"eric gisse" <jowr.pi.nospam(a)gmail.com> wrote in message news:hib6j8$ri5$1(a)news.eternal-september.org... > ..@..(Henry Wilson DSc) wrote: > >> On Sat, 09 Jan 2010 12:40:44 -0800, eric gisse <jowr.pi.nospam(a)gmail.com> >> wrote: >> >>>Anti Vigilante wrote: >>>[...] >>> >>>> It's worse. If c+v is possible then that front signal may reach the >>>> back >>>> a long time after the front stops. This suggests that c+v has >>>> relativistic features as well. Something that is quite interesting. >>> >>>Mh-hmm. >>> >>>This is the repeatedly mentioned 'bunching' that is not observed but >>>repeatedly discussed. Henri 'escapes' this problem by babbling bullshit >>>about extinction which manages to conspire to make everything look like >>>relativity is true. >> >> There are molecules throughout space. If a degree of extinction DID NOT >> occur, it would be hard to explain why. > [...] |