SR and a lightbulb
in [Relativity]
|
From: Androcles on 8 Jan 2010 13:17 "Henry Wilson DSc" <..@..> wrote in message news:t12ek51l9gi3vdeg87l58ct6e1k2bv59si(a)4ax.com... > On Fri, 8 Jan 2010 04:50:36 -0000, "Androcles" > <Headmaster(a)Hogwarts.physics_r> > wrote: > >> >>"Henry Wilson DSc" <..@..> wrote in message >>news:lbadk5tiq3l4cpnagmft2rnivbl3jmo1io(a)4ax.com... >>> On Fri, 8 Jan 2010 01:51:50 -0000, "Androcles" >>> <Headmaster(a)Hogwarts.physics_r> >>> wrote: >>> >>>> >>>>"eric gisse" <jowr.pi.nospam(a)gmail.com> wrote in message >>>>news:hi5pqa$ibd$2(a)news.eternal-september.org... >>>>> ..@..(Henry Wilson DSc) wrote: >>>>> >>>>>> On Thu, 7 Jan 2010 12:55:33 -0800 (PST), PD >>>>>> <thedraperfamily(a)gmail.com> >>>>>> wrote: >>>>>> >>>>>>>On Jan 7, 2:41 pm, ..@..(Henry Wilson DSc) wrote: >>>>>>>> On Thu, 7 Jan 2010 06:54:28 -0800 (PST), PD >>>>>>>> <thedraperfam...(a)gmail.com> >>>>>>>> wrote: >>>>>>>> >On Jan 6, 6:29 pm, ..@..(Henry Wilson DSc) wrote: >>>>>> >>>>>>>> >This has nothing to do with what humans see. This is a matter of >>>>>>>> >whether the barn door strikes the pole or not, which can be >>>>>>>> >recorded >>>>>>>> >with or without humans present. >>>>>>>> >>>>>>>> >Now: At the time when the front of the pole hits the back wall of >>>>>>>> >the >>>>>>>> >barn, what happens to the back end of the pole AT THAT INSTANT? >>>>>>>> >>>>>>>> At any particular instant...or if time diesn't even exist ...the >>>>>>>> two >>>>>>>> ends of the pole are separated by the same absolute spatial >>>>>>>> interval. >>>>>>> >>>>>>>I'll be a little more precise: At the instant when the motion of the >>>>>>>front of the pole stops as it hits the back wall of the barn, what >>>>>>>happens to the motion of the back of the pole? >>>>>> >>>>>> It stops instantly as well. Reality doesn't rely on what humans see. >>>>> >>>>[...] >>>>> >>>>> [...] >>> >>> Gawd! It's quiet in here... >> >>I'm chatting with Gisse. > > the why don't you answer his [...] I did, I said "[...]" right back at him to be agreeable. I could have contradicted him with <snip> or [snip], but that might have started a flame war.
From: Androcles on 8 Jan 2010 15:02 "eric gisse" <jowr.pi.nospam(a)gmail.com> wrote in message news:hi7spl$p4q$4(a)news.eternal-september.org... > 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.) [...] >> >> 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.) > [...]
From: Inertial on 8 Jan 2010 19:08 "train" <gehan.ameresekere(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. However, the door itself can go smashing thru the rod faster than the speed, destroying the rod along the way > A fine pickle we have > here. Do we want to do a pickle in the barn scenario now? > 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 > 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.
From: YBM on 9 Jan 2010 00:36 Henry Wilson DSc a �crit : > On Fri, 8 Jan 2010 09:29:26 -0800 (PST), PD <thedraperfamily(a)gmail.com> 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: >>>> 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: >>>>>> No, relativity does NOT say that. The OP thought that relativity says >>>>>> that, but he was incorrect. His error was precisely the one I just >>>>>> pointed out. >>>>> You only pointed out that humans perceive a distorted view of reality because >>>>> of their reliance on light, which travels at a finite speed. >>>> I pointed out that there was no internal contradiction in relativity, >>>> which you claimed there was, and which the OP thought was there too, >>>> both of you erroneously. >>> there is no internal contradiction in much of Earth centrism either...or 'flat >>> Earthism'.... >>> >> But you said there WAS an internal contradiction in relativity and >> this example pointed it out. And that was wrong. >> But instead of admitting that your claim of internal contradiction was >> wrong, you say SR is wrong anyway. > > SR is consistent to a point...... consistently wrong.......then it breaks down. Chicken, chicken, chicken! You are a chicken, Ralph Rabbidge.
From: Androcles on 9 Jan 2010 01:09
"Henry Wilson DSc" <..@..> wrote in message news:9d4gk5l0viq77uacrapp78arrr84sm18dh(a)4ax.com... > On Fri, 8 Jan 2010 18:17:53 -0000, "Androcles" > <Headmaster(a)Hogwarts.physics_r> > wrote: > >> >>"Henry Wilson DSc" <..@..> wrote in message >>news:t12ek51l9gi3vdeg87l58ct6e1k2bv59si(a)4ax.com... >>> On Fri, 8 Jan 2010 04:50:36 -0000, "Androcles" >>> <Headmaster(a)Hogwarts.physics_r> >>> wrote: > >>>>>>>> It stops instantly as well. Reality doesn't rely on what humans >>>>>>>> see. >>>>>>> >>>>>>[...] >>>>>>> >>>>>>> [...] >>>>> >>>>> Gawd! It's quiet in here... >>>> >>>>I'm chatting with Gisse. >>> >>> the why don't you answer his [...] >> >> I did, I said "[...]" right back at him to be agreeable. >>I could have contradicted him with <snip> or [snip], >>but that might have started a flame war. > > How about a [...]! > That has him stumped. He never replies to it, he agrees with it, it is one of his favourite phrases. |