SR and a lightbulb
in [Relativity]
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From: Inertial on 11 Jan 2010 23:09 "Henry Wilson DSc" <..@..> wrote in message news:deonk5ppbljekfu3meoog3m3tpi2b53hta(a)4ax.com... > On Tue, 12 Jan 2010 12:22:18 +1100, "Inertial" <relatively(a)rest.com> > wrote: > >> >>"Paul B. Andersen" <paul.b.andersen(a)somewhere.no> wrote in message >>news:hifdd4$m3u$1(a)news01.tp.hist.no... > >>> >>> Of course! >>> It's pretty stupid to think that after a century >>> of scrutiny, a scenario can be found where SR >>> predicts two different outcomes of the same scenario. >> >>Thanks paul .. nicely put. pretty much what I was saying .. current does >>not flow in the circuit instantly (ie if it did, that would mean the >>information about the circuit being completed would have to travel >>instantly >>from one end of the connection to the other). And at the speed of >>connection/disconnection the scenario put forward, there would not be time >>for a light bulb to glow anyway. > > Listen you pair of dopey bastards, the current doesn't have to flow > immediately. Didn't say it did > Paul has written irrlevant bullshit. Don't you have any idea of > practical physics. BAHAH .. you wouldn't know physics if it hit you in the head. > All that is required is a signal that the contacts are adjacent. Fine .. such a signal would arrive at the bulb at the same time > The message > can be amplified to cause the light to flash at any time. So you're changing the scenario now. That's fine .. it still doesn't refute SR > That doesn't alter the fact that the contacts are adjacent in only ONE > frame. They are adjacent in every frame. The two sets are not adjacent at the same TIME in every frame. However, any signal going from the contacts to the bulb (or whatever you are replacing it with) will arrive at the same time in every frame (or in none if not constructed correctly). So you've still to show how this would show SR is not self-consistent or predicts contradictory results.
From: Paul B. Andersen on 12 Jan 2010 09:26 On 12.01.2010 03:47, Henry Wilson DSc wrote: > On Tue, 12 Jan 2010 12:22:18 +1100, "Inertial"<relatively(a)rest.com> wrote: > >> >> "Paul B. Andersen"<paul.b.andersen(a)somewhere.no> wrote in message >> news:hifdd4$m3u$1(a)news01.tp.hist.no... > >>> >>> Of course! >>> It's pretty stupid to think that after a century >>> of scrutiny, a scenario can be found where SR >>> predicts two different outcomes of the same scenario. >> >> Thanks paul .. nicely put. pretty much what I was saying .. current does >> not flow in the circuit instantly (ie if it did, that would mean the >> information about the circuit being completed would have to travel instantly >>from one end of the connection to the other). And at the speed of >> connection/disconnection the scenario put forward, there would not be time >> for a light bulb to glow anyway. > > Listen you pair of dopey bastards, the current doesn't have to flow > immediately. Paul has written irrlevant bullshit. Don't you have any idea of > practical physics. You have a funny idea of what is practical physics, Ralph. I can tell you that transmission of short pulses on a transmission line (any wire is a transmission line) is very practical physics indeed. I have practical experience with sub ns pulses on transmission lines. Have you? Blazingly obvious not! > All that is required is a signal that the contacts are adjacent.The message > can be amplified to cause the light to flash at any time. No contacts are adjacent when the light bulb flashes. When the information that one end makes contact reaches the light bulb, there is no contact. The only way this information can reach the light bulb is in the form of a short pulse on the wire, and this pulse cannot go faster than light. Any kind of amplification could only delay it. So we have one pulse from each side, and the light bulb would flash whether or not they reach the light bulb simultaneously. (Of course no light bulb would flash for such a short pulse, but you could make a fast detector which made the bulb flash. Here you can put your amplifier.) > That doesn't alter the fact that the contacts are adjacent in only ONE frame. You probably mean that the contacts are adjacent simultaneously in only one frame. That is correct. But the information (pulses) would reach the light bulb simulatneously in all frames. Of course! This is a single event. Either the pulses reach the bulb simultaneously, or they don't. It can't be but one opinion about that. "Ends make contact" are _two_ separate events. Whether or not these are simultaneous is a matter of opinion. The simultaneity of two separate events is an abstraction with no physical consequences. A (more or less) arbitrary definition of a concept can't have physical consequences. And this is what I showed in my posting. But that is way beyond your capabilities, so you will never understand it. Which you now have demonstrated. Again. Thanks. Again. -- Paul http://home.c2i.net/pb_andersen/
From: Edward Green on 18 Jan 2010 19:54 On Dec 29 2009, 9:39 pm, dk <dakalami...(a)sci.ccny.cuny.edu> wrote: > Hi to all, > > Consider the following scenario: > > In frame S thare are two points, x1 and x2, a distance L apart. There > are wires running from these two points such that x1 and x2 are > connected to the '+' and '-' terminals of a battery in S. Now, > image a lightbulb device with straight segments of wire extending from > each of its terminals. The lightbulb device, in frame S', is moving > with velocity v parallel and very close to the x axis of frame S. An > observer in S notices that the lightbulb momentarily flashes as it > passes by the x1-x2 region. This S observer correctly concludes that > the length of the wire segments of the lightbulb device added up to > exactly length L, since the lightbulb flashed, implying that the > endpoints of those wires simultaneously coincided with x1 and x2, > respectively, in S---Otherwise the circuit would not be complete and > the lightbulb would not flash. However, since the observer in S will > measure a length L for the lightbulb device, an observer at rest in S' > will have to measure a proper length L' that is greater than L. > Therefore, in frame S', the endpoints of the lightbulb device never > coincide with x1 and x2 and the circuit never completes. How does the > observer in S' explain the objective fact of the lightbulb flashing? Capacitance.
From: Edward Green on 18 Jan 2010 20:00
On Jan 7, 7:35 pm, Darwin123 <drosen0...(a)yahoo.com> wrote: > On Dec 29 2009, 10:17 pm, dlzc <dl...(a)cox.net> wrote:> On Dec 29, 7:46 pm, dk <dakalami...(a)sci.ccny.cuny.edu> wrote: > > > > I should have mentioned that it is assumed > > > that the wires on the lightbulb device are > > > insulated and only at their endpoints is the > > > conductor exposed so as to make contact with > > > x1 and x2 in frame S. > > > Draw a diagram. How are the wires oriented wrt the x axis? > > > Next, wires have inductance. Only in a fantasy world does the light > > "flash". > > I would like to add: > "Wires have an inductance. therefore the signal traveling from switch > to light bulb has to move slower than the speed of light. you have to > include the propagation time of the electric power once the circuit is > complete. Most of the signal upon completing the circuit will actually > move slower than the speed of light. Plus the fact that the filament > needs time to heat. > To facilitate the discussion, assume that the signal moves from > switch to light bulb at the speed of light, and that the light bulb > heats up "instantly." Also include the propagation time of the light > from bulb to observers." Methinks you assume too much. It's precisely details like the distributed capacitance and inductance of the wires which will account for a possible flash in the frame in which the circuit is never completed simultaneously. Hell ... you could get a light bulb to flash, given enough wire, if you never completed the circuit in any frame. |