Ballistic Theory, Progress report...Suitable for 5yo Kids
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From: george@briar.demon.co.uk on 15 Sep 2005 08:10 jgr...(a)seol.net.au wrote: > George Dishman wrote: > > <jgreen(a)seol.net.au> wrote in message > > news:1126564087.777831.76000(a)g43g2000cwa.googlegroups.com... > > > > > > George Dishman wrote: > > >> <jgreen(a)seol.net.au> wrote in message > > >> news:1126405408.815651.120520(a)f14g2000cwb.googlegroups.com... > > >> > > > >> > Jeff Root wrote: > > >> >> Jim Greenfield replied to Jeff Root: > > >> ... > > >> > > > The earth rotates, revolves (sun), > > > the milky way galaxy spins (probably on more than one axis), has > > > motion ref > > > other galaxies, globular clusters probably move ref each other......... > > > the entire visible universe may be a unit moving ref other unseen > > > 'parts' of the infinity. > > > So we/you have no idea what the net motion of train or track is. > > > (and never will :-( ) > > > > To the person on the car, the car is not moving but > > the Earth, Sun, galaxies and clusters are moving. > > You speak about "net motion" as if it had some other > > meaning but it just means combining several, for > > example combining the motion of the galaxies relative > > to the Sun to that of the Sun relative to the railcar > > to get the motion of the galaxies relative to the > > railcar. > > The old chestnut! Jim, you introduced it with your talk of Archimedes on the ship. Why bring it up if you dislike it? You need to try to be consistent if you want this conversation to go anywhere. > If I could plot the center of the universe, with a > good enough computer, FoRs become redundant, because ALL calculations > to be made from there. :-( Unless you are suggesting light always travels at c relative to the centre of the universe, the concept of a "center of the universe" is irrelevant. As you know current models do not have a centre. We can 'plot the Earth' so the 'center of the universe' is redundant as 'ALL calculations can be made from the Earth. We can 'plot the railcar' so the 'center of the Earth' is redundant as ALL calculations can be made from the car. A few lines below this you said exactly the same thing: > It doesn't matter whether we consider train or earth moving; just > reverse paths. Make your Mind up Jim. > > >> > Rubbish! Read above again to realise that he IS mistaken- and I can > > >> > prove it! Cut a hole in the floor, and where before the train rider was > > >> > SURE that the beam is vertical, he actually finds out that he was > > >> > mistaken/WRONG, when he sees the beam MISS the eaths centre (flat > > >> > earth) > > >> > > >> We went over this many times Jim but you seem to > > >> have forgotten it all. In the scenario where the > > >> train is moving, the Earth is moving sideways > > >> (inertial motion) with the centre directly below > > >> at the moment the light is emitted so he also > > >> expects the light to miss the centre. > > > > > > If he expects the light to have its path altered (miss the center), > > > then he also knows that it is travelling a longer path (diagonal). > > > > In the first situation, the light moves vertically > > from the ceiling to the floor and through the hole. > > It goes on to hit the centre of the Earth which is > > directly below at all times. In the second scenario, > > the light moves vertically from the ceiling to the > > floor and through the hole. > > No. From the instant photon leaves bulb, it is going to miss earth > center. Pay attention Jim, I said "In the first situation" which is where the train isn't moving along the track so the light does hit the centre. > Hole in floor hasn't much to do with anything- all I was trying > to show is that photon path is altered by train motion, and travels a > longer (diagonal) path through the universe, whether the passenger is > aware of that, or not. > > > At that moment, the > > centre of the Earth was directly below the hole but > > moving sideways. The light goes on vertically > > downwards but the Earth has moved to the side by > > the time the light gets to where the centre was so > > it misses. > > It doesn't matter whether we consider train or earth moving; just > reverse paths. Exactly my point. Now apply that to both your scenarios. > > > If he still thinks it will take the same time to reach the floor, then > > > ergo it is travelling FASTER along the diagonal- UNLESS apriori his > > > speed measurer (clock) has been tweaked. This is what AE did, and > > > afraid to say, you as well > > > > Why should the fact that the Earth was moving in the > > second scenario cause the speed of the light between > > the ceiling and the floor to change? > > Smack for Jeff! > He says .... I'm not going to comment on Jeff's posts, you switch back and forth between different situations so much I can't guess whether he was taling of the Galilean version, SR, Ritz or what. If you raise consistent questions we will be able to give consuistent answers. So far I haven't seen Jef make any significant errors and I commented on any ambiguity I saw. > the clocks of passenger (pa) and platform observer (po) are > operating together. So with train moving, pa stops his watch when beam > hits floor, and so does po. Po has measured a longer path from > emmission point. IIff c is the same along both paths, more time must > show on po's clock, and therefore photon took longer time (both clocks > identical, remember) according to po. I maintain that both will read > the same Maintain all you like, it doesn't happen in practice. > , as the longer path was traversed at a higher speed. > Although claims to the contrary abound, where are these "thousands" of > measurements from various sources? Apart from high energy > establishments, where a ruler is not a distance, but a time interval, When muons generated by cosmic rays reach the ground, the ruler is the height of the atmosphere. > and time is interprted as a distance travelled by emr, WHERE are the > experiments? Binaries seem to be the only references, I have told you over and over again, the Sagnac effect which is used in devices around the world and is seen in many other disciplines. > and sure as eggs, > the distances to them, frequencies, periods, wavelengths etc are ALL > derived from data which apriori(new word- hope its spelt right!) Two words, "a priori". > assumed c=c+v, and frequency and wavelengths altered as per SR/GR > dogma. > > <snip> > > No, [whoever] reckoned there was no way you could > > tell even if you _could_ see out because saying > > "the ship is moving through the sea" and "the sea > > is moving past the ship" are equivalent descriptions > > of the same relative motion. > > > > > A sudden stop would have told him there was a > > > change in his velocity, but did the ship hit a reef (was already in > > > motion, or did it accellerate( assuming he didn't know fore from aft)? > > > > Yes, we know acceleration can be detected (in SR > > or deviation from freefall in GR). > > I am not referring to acceleration- ... Yes you are, you said "A sudden stop would have told him there was a change in his velocity.." and a change in velocity is an acceleration. Try to produce a consistent argument Jim. > ONLY velocity. Remember, the pa > fell asleep. This is important, and goes back to our discussions on > doppler (trains) > Detecting acceleration is a given (?), it is the v under discussion. > > > > > He needed 'Jim's Motion Detector'. This consisits of a monochromatic > > > light source (set single frequency/wavelength) and a filter which will > > > allow ONLY that frequ to pass through, the two being constructed in the > > > same frame. Because c'=c+v, Arch will know when his motion has changed > > > from that in which the Detector was assembled, when the filter blocks > > > the beam- the frequency has altered! > > > > It won't work since all the components move together, > > any Doppler shift cancels. Only relative motion produces > > a change. > > But there IS relative motion; the port! No Jim, you said "This consists of a monochromatic light source .... and a filter ... the two being constructed in the same frame." If they are in the same frame, there is no relative motion. Try to produce a consistent explanation Jim. > and acceleration has taken > place since (but not continuing). This is a wooden boat, George. I can > point the filter at a source elsewhere (back in port). THAT is the > signal which is blocked due to the changed motion ref port. You see, I > do have a machine to detect my motion, without MYSELF seeing out; I > just watch the filter, and note when signals are blocked. I deduce what > is happening (happened), and that is what pa should do, in order to > avoid being mistaken. > > > > > Now NASA "knows" this, because they have to alter their filters (read > > > radio receivers) when the motion of space craft ref earth > > > alters........ but the AE component subscribes the phenomenon to magic! > > > > Different thing, that is relative motion so obviously > > there is Doppler. In fact the Doppler measured by > > NASA matches the SR formula anyway so confirms SR. > > Doppler is NOT a cause, it is an EFFECT. Yes, it is an effect caused by _relative_ motion and you said "motion of space craft ref earth" whereas your detector had the source and the filter "in the same frame". <snip> > > Nope. Speed is defined as distance as measured divided > > by time as measured. He measures the distance and > > measures the time and divides and that gives the correct > > value of speed as per the definition. If you don't like > > the definition, lobby to have the dictionary changed. > > That would also rewrite every book on physics of course > > so I don't think you will succeed. until you do, I will > > stick with the usual formula. > > It will happen! ... No it won't, speed wil always be defined as the measured distance divided by the measured time. <snip> > > > Well, we are stuck, because as Henri points out (and I have asked for > > > experimental evidence since whenever), experiments as to c'=c+v or > > > otherwise have NEVER been done! > > > > Oh dear Jim, you're not having a good day. Haven't you > > seen Henri's long threads on binary stars? De Sitter > > pointed out that this was a test of light from a moving > > source in 1913, the same year that Sagnac performed his > > experiment. You know perfectly well that the Sagnac > > experiment measures the speed of light from a source on > > a rotating platform because we discussed it at length > > over last Christmas. That experiment has been done > > thousands of times and there are commercial devices using > > it every day. > > Well how this?? > Think on the scenario for Lorentz contraction due to velocity. No Jim, instead of everyone having to think about what you want, how about you think about what I said for a change and you stop saying the test has never been done when I have shown you commercial devices that do that test all the time they are working. > Engine driver shines a beam back down the moving (forward)train. As the > rear is coming on to meet the beam, he deduces that the train has > shrunk, as c was the same as for a stationary train. The guard shines > his beam forward; as the engine is going AWAY FROM the beam, HE deduces > that the train has STRETCHED. > Nothing happens to the train!!!!!!!!!!! BOTH are victims of illusion, > and when doing their calculations later, should realise that their > motion DID NOT CEASE when their respective flashes were sent. > AE first mistake: c=c+v > " second : not spotting LTs selective signage The fact that you cannot comprehend SR is not an argument against it. SR says the train was not stretched but that our method of measurement will show a different value depending on whether the ruler is moving past the train (or vice versa - they're the same thing) or at rest next to it. The cause is simple geometry but understanding that appears to be beyond you. Whatever the reason, writing arguments against some wierd stretching of the train to try to disprove SR is pointless when SR says nothing of the kind happens. George
From: george@briar.demon.co.uk on 15 Sep 2005 08:33 jgr...(a)seol.net.au wrote: > Jeff Root wrote: > > Jim Greenfield replied to Jeff Root: < big snips - only answering points relevant to me > > > Clocks are not self-altering. Clocks are not altered by > > moving relative to an observer. What is altered is the > > relationship between the observer and what he is observing. > > When that relationship is altered, the measurements will > > be different. > > Well George says we set the clocks going, go to the pub, and then come > back and read the results. I fear you are confused as to what he/you > understand SR to be, ... Nope, Jeff said exactly what I have said many times, a perfect clock produces the same number of ticks per unit of proper time regardless of motion. It is the relationship (angle) between the proper time of one clock and that of another that produces the difference in rate, again exactly as Jeff said. > > > The animation as sent to me (have you actually SEEN it?) > > > > No, but George explained it well. > > So you are arguing strongly in support of something you haven't seen? No, he is saying that he understood my explanation of why I wrote it the way I did. Perhaps you should have listened to what I said then you might understand too. He doesn't need to see the animation to know what I was trying to do, that's what he told you: > > You don't understand what the animation shows. You don't > > understand *why* the clocks are not synchronized. You > > don't understand what the animation is intended to show. > > > > Even after George explained it to you again. > > Attn George! > I first realised the mistake in the diagrams sent you ref SR from "Time > Magazine" while watching a glowing insect flying around in pitch > darkness. It dawned on me, that if my eyes didn't swivel, neck turn, or > gravity appraise me of the vertical, I would have no idea of the > motion, if any, of that bug. Look at the po! If he was in the dark, HE > would have no more idea of what was happening to the ray in the > carriage, than would the pa. On a coal dark night, his conclusion would > be exactly that of the pa, who were HE in the dark, ALSO wouldn't know > what the photon was doing. The whole scenario is based on SELECTIVE > INFORMATION GIVEN THE OBSERVERS. Speed is defined as the distance divided by the time. All he needs to know is that the light travelled in a straight line from source to detector. He mesures the straight line distance and the time and divides and that is the end of the question, he has his measured speed. You can give him all the extra information in the universe but it won't make the slightest difference because no other information can be used in the equation v = d / t. > Similarly for a moving train: does it only shrink for those with good > sight, and not for the blind, or only when the lights are on? > And what if I use some other communication , other than light? If I > string a wire the length of the train, and send a 'tap' down/up the > wire, will I find evidence of contraction (or stretching if the guard > does it)??? Measure the length of a straight piece of string with a ruler parallel to the string and you get one value. Lay the ruler at an angle to the string and draw lines perpendicular to the ruler to the ends of the string and you get a different number. Use two ruler, one parallel and one at an angle and you get two different values at the same time for the same piece of string, obviously it hasn't shrunk. The same mechanism in 4D explains why the length of the train is different depending on whether the instruments are moving past it or not, so your gibbering on about things shrinking is of no interest to anyone. George
From: Jeff Root on 15 Sep 2005 14:33 George replied to Jim: >> Smack for Jeff! >> He says .... > > I'm not going to comment on Jeff's posts, you switch > back and forth between different situations so much > I can't guess whether he was talking of the Galilean > version, SR, Ritz or what. None of the above. I never said what Jim claimed I said. -- Jeff, in Minneapolis
From: Jeff Root on 15 Sep 2005 14:57 Jim Greenfield wrote: > Smack for Jeff! > He says the clocks of passenger (pa) and platform > observer (po) are operating together. I never said any such thing. -- Jeff, in Minneapolis
From: Jeff Root on 15 Sep 2005 15:42
George Dishman replied to Jim Greenfield: >> >> He needed 'Jim's Motion Detector'. This consisits of a >> >> monochromatic light source (set single frequency/wavelength) >> >> and a filter which will allow ONLY that frequ to pass through, >> >> the two being constructed in the same frame. Because c'=c+v, >> >> Arch will know when his motion has changed from that in which >> >> the Detector was assembled, when the filter blocks >> >> the beam- the frequency has altered! >> > >> > It won't work since all the components move together, >> > any Doppler shift cancels. Only relative motion produces >> > a change. >> >> But there IS relative motion; the port! > > No Jim, you said "This consists of a monochromatic light source > ... and a filter ... the two being constructed in the same frame." George, He meant that the monochromatic light source and the filter were both constructed in the same reference frame. Like, the same factory. What he described is an extremely limited version of a common radio navigational aid. -- Jeff, in Minneapolis |