It's the new year, and I'm really really sad we have to had more than 200 exchanges for this obvious mf troll.... we are the everything list, a mailing list which exists for almost 30 years, I was 17 years old when I discovered it, and now the only discussion left is alan Grayson and cosmin stupid... what a disgrace it is ? Anyway happy new year to you all, even to the trolls.
Le mar. 31 déc. 2024, 22:31, Jesse Mazer <[email protected]> a écrit : > > > On Tue, Dec 31, 2024 at 12:57 AM Alan Grayson <[email protected]> > wrote: > >> >> >> On Monday, December 30, 2024 at 1:03:20 PM UTC-7 Jesse Mazer wrote: >> >> On Sat, Dec 28, 2024 at 1:51 AM Alan Grayson <[email protected]> wrote: >> >> >> >> On Friday, December 27, 2024 at 10:05:51 PM UTC-7 Jesse Mazer wrote: >> >> >> >> On Friday, December 27, 2024, Alan Grayson <[email protected]> wrote: >> >> >> >> On Friday, December 27, 2024 at 6:48:56 PM UTC-7 Jesse Mazer wrote: >> >> On Fri, Dec 27, 2024 at 4:58 PM Alan Grayson <[email protected]> wrote: >> >> On Friday, December 27, 2024 at 9:16:39 AM UTC-7 Jesse Mazer wrote: >> >> On Friday, December 27, 2024, Alan Grayson <[email protected]> wrote: >> >> On Thursday, December 26, 2024 at 9:39:41 PM UTC-7 Jesse Mazer wrote: >> >> On Thursday, December 26, 2024, Alan Grayson <[email protected]> wrote: >> >> On Thursday, December 26, 2024 at 2:56:04 PM UTC-7 Jesse Mazer wrote: >> >> On Thursday, December 26, 2024, Alan Grayson <[email protected]> wrote: >> >> On Thursday, December 26, 2024 at 3:26:41 AM UTC-7 Alan Grayson wrote: >> >> On Thursday, December 26, 2024 at 12:12:43 AM UTC-7 Jesse Mazer wrote: >> >> On Wednesday, December 25, 2024, Alan Grayson <[email protected]> >> wrote: >> >> On Wednesday, December 25, 2024 at 5:14:21 PM UTC-7 Jesse Mazer >> wrote: >> >> On Wednesday, December 25, 2024, Alan Grayson <[email protected]> >> wrote: >> >> *Why do refer to transformations that don't preserve time ordering? IIUC, >> such transformations only occur when assuming motion faster than light. * >> >> >> No, that’s not correct. Motion faster than light would be required if >> there was a claim of causal influence between events with a spacelike >> separation; but there’s no such claim here; in both Brent’s example and >> mine, if we consider the event A of the back of the car passing the front >> of the garage and the event B of the front of the car reaching the back of >> the garage, there is a spacelike separation between those events, and >> neither event has a causal influence on the other. >> >> >> *I'm asking a general question. Why do you refer to failure of time >> ordering? What was the point you thought you were making? AG* >> >> >> Because as you previously agreed, the question of whether the car fits >> reduces to the question of whether the event A = back of car passes front >> of garage happens before, after, or simultaneously with the event B = front >> of car reaches back of garage. Since these events have a spacelike >> separation in both Brent’s and my numerical examples, in relativity >> different frames can disagree on their order, that’s the whole reason we >> say frames disagree on whether the car fits. >> >> >> *As I recall, you were writing about the failure of TIME ordering, and >> this would mean violation of causality, not what we're discussing on this >> thread. AG * >> >> >> You either recall incorrectly or misunderstood at the time, but >> disagreement about the time ordering of two events A and B does NOT imply >> any violation of causality; it just implies the spacetime interval between >> A and B is spacelike, but normally this is combined with the assumption >> that there are no causal influences between events with a spacelike >> separation. >> >> Do you understand what the spacetime interval is? If I gave you the >> difference in time coordinates T = tB - tA for the two events along with >> the difference in position coordinates X = xB - xA, would you know how to >> calculate the spacetime interval and judge whether it is timelike, >> spacelike or lightlike? >> >> >> >> >> *But if so, you're not within the postulates of SR, which is what this >> discussion is about. So what point do you think you're making? AG* >> >> *Re: paradox: Assume there's an observer located in the garage. This >> observer is in the garage frame. This observer sees the car easily fit in >> the garage. Imagine another observer riding in the car. This observer is in >> the car frame and observes being in the garage but never fitting in the >> garage. What are the observations when the two observers pass each other, >> in juxtaposed positions?* >> >> >> I’ve asked this before, but by “see” do you mean in terms of when the >> light from different events reaches their eyes, or something more abstract >> like a computer animation they create of when events occur in their frame, >> once they have measured the time and position coordinates of all events >> using local readings on rulers and clocks at rest relative to themselves? >> >> >> *Nothing more abstract. One observer sees the car sticking outside the >> back of garage, the other sees it inside, when both are juxtaposed. * >> >> >> You didn’t quite answer my question—you are just talking about what they >> see with their eyes, right? >> >> >> *I used the word "see". Is this not clear enough? AG* >> >> >> >> Not entirely, since it’s routine in relativity problems to use words >> differently from everyday speech, for example in ordinary speech when you >> talk about “observing” some event we are usually talking about visual >> sight, but in relativity talking about what someone “observes” always >> refers to how things happen in the coordinates of their frame, not to >> visual sight. >> >> >> >> If so, there is no disagreement between observers passing through the >> same point in spacetime about whether the car fits in a visual sense. >> >> >> *Really? So if the garage is 10' long in rest frame, * >> >> >> Do you mean 10’ in the garage’s rest frame? As I said before, just using >> “rest frame” without specifying a particular object is unclear. >> >> >> *I appreciate your thoroughness but here I just left out "its", as in >> "... 10' long in its rest frame", and I think you should have easily >> inferred my meaning. AG * >> >> >> Given that you had recently objected to my use of the phrases “car’s rest >> frame” and “garage’s rest frame” and hadn’t acknowledged my response about >> how this is a standard way of speaking in relativity, I didn’t think it was >> safe to assume that. It would help if you would acknowledge when something >> I’ve said has led you to revise a view, even on something minor like >> terminology, otherwise I don’t know when a given point needs to be >> re-litigated. The recent discussion about how we can talk about events that >> are spacelike separated without implying any faster than light causal >> influence is another example; do I need to keep arguing that or does the >> fact that you dropped that discussion mean you concede the point? >> >> >> Could you please address my comment above so I know if we’re in >> disagreement on these points? >> >> >> *I don't object to your terminology. As I stated, if I had included "its" >> in my statement, there would have been no ambiguity about terminology. And >> as far as I can recall, I never objected to the use of your quoted >> statements about rest frames. AG* >> >> >> You objected multiple times in the last few days to my terminology where >> "car's rest frame" refers to the frame where the car is at rest (i.e. it >> has position coordinates that don't change with time) and the garage is >> moving (so the garage is Lorentz-contracted in the car's rest frame), while >> "garage's rest frame" symmetrically refers to the frame where the garage is >> at rest and the car is moving (so the car is Lorentz-contracted in the >> garage's rest frame). For example in the post at >> https://groups.google.com/g/everything-list/c/vcrAzg4HSSc/m/XZrHB-IdAwAJ >> I said: >> >> "In garage rest frame, garage has length 20 and car has length 25/1.25 = >> 20. In the car rest frame, the garage has length 20/1.25 = 16 and the car >> has length 25.” >> >> And you responded: >> >> "OK, assuming car is moving, but I wouldn't call that "in the car rest >> frame" since you have garage length as contracted. AG" >> >> Then at >> https://groups.google.com/g/everything-list/c/vcrAzg4HSSc/m/mFVsDGUtAwAJ >> you responded by imagining “the rest frame” referred to some imaginary >> initial conditions that were never part of the problem I described, >> conditions where both the car and garage were at rest relative to each >> other: >> >> “IMO, the rest frame is defined as the initial conditions in this problem >> when the car isn't moving, and is longer than the garage. When the car is >> moving, we have been calling the other two frames, simply the car frame and >> the garage frame.” >> >> Then at >> https://groups.google.com/g/everything-list/c/vcrAzg4HSSc/m/1AWAOHA4AwAJ >> you again objected to the standard terminology in which “car’s rest frame” >> just refers to the frame where the car is at rest in the sense of having a >> fixed position coordinate, even if it is moving relative to the garage: >> >> “No one uses "rest frame" when describing the results in either frame >> when the car is moving. You introduced that terminology recently, claiming >> it is standard. AG” >> >> Then just yesterday at >> https://groups.google.com/g/everything-list/c/vcrAzg4HSSc/m/O12FCXvmAwAJ >> you again objected to this standard terminology: >> >> “What could be the meaning of "rest frame" associated with "garage"? I >> don't have a clue. Shall we consult Webster's Dictionary?” >> >> >> *I was being sarcastic. Not to be taken at face value. AG * >> >> >> The Webster’s dictionary comment was sarcastic, but ‘What could be the >> meaning of “rest frame” associated with “garage”?’ didn’t seem to be a >> sarcastic question, especially since it echoed your confusion in the other >> comments I quoted. >> >> >> >> >> >> So it would be helpful to know if you're willing to accept that my use of >> "car's rest frame" and "garage's rest frame" is the standard way of talking >> among physicists, or if you still object. >> >> >> *Instead of haggling over this issue, and possibly taking some of my >> comments out of context, we agree that when using the LT from either frame, >> the car or garage length in that frame has not changed from its initial >> condition, 12' or 10', respectively.* >> >> >> I don’t know what you mean by “its initial condition.” Do you just mean >> its length its own rest frame? Or do you think it’s essential to the >> problem that we imagine some initial condition where both are at rest >> relative to each other, and then the car is accelerated? If so I would >> definitely object to that, the term “car’s rest frame” has no such >> implications, it would have exactly the same meaning if we assumed the car >> and garage have had a fixed relative velocity for an infinite time prior to >> the car passing through the garage. >> >> >> * At that point it was agreed that car cannot fit in garage because of >> length considerations. Consequently, following that agreement, I calculated >> using the LT, that the car fits or not -- fits in garage frame, doesn't fit >> in **car frame -- based solely on length considerations. **If the car >> can't fit from its frame when v = 0, it can't fit for any v > 0, since the >> garage gets even shorter. I think you and Brent believe it can't fit in car >> frame due to disagreement about simultaneity, whereas I use length >> contraction to reach the same conclusion. * >> >> >> I didn’t use any word like “because” or talk about the best conceptual >> explanation, I just said that the question of whether the car fits in some >> frame is *equivalent* to the question of the order of the events A and B in >> that frame. It is of course also equivalent to the question of whether the >> length of the car is shorter, greater, or equal to the length of the garage >> in that frame. Equivalent here just means logical equivalence, ie the truth >> value of the statement “the car doesn’t fit in this frame” is guaranteed to >> be the same as the truth-value of “B happens before A in this frame” and >> *also* the same as the truth-value of “the car is longer than the garage in >> this frame”; it’s impossible in either relativity or classical physics for >> one of these statements to be true while another one is false, or vice >> versa. Do you agree they are equivalent in that sense? >> >> >> Could you address my question here about whether you agree that, given >> the clarification that I am talking about logical equivalence in the sense >> I discussed above, the question of whether the car fits is completely >> equivalent to question of the order of the events A="back of car passes >> front of garage" and B="front of car reaches back of garage"? >> >> >> *I apologize for being so dumb, but whereas I'm comfortable using >> relative lengths of car and garage to determine fitting or not, I don't >> really understand that the reversal of time order, of event B preceding >> event A, is equivalent to car not fitting in garage.* >> > > OK, but are you making an effort to understand? In general do you > actually want to understand what relativity says about these matters, or do > you just want to score a rhetorical "win" for your own arguments? If you're > interested in understanding rather than winning then you can't just stick > by whatever way of thinking is most comfortable for you, or most conducive > to your argument. > > *Concerning those videos, two which were reviewed on this MB, one by Brent >> and one by you, they falsely claim to show that from the car frame, the car >> really does fit in the garage.* >> > > I watched the video and I never saw him make the false claim that the pole > (which takes the place of a car in that video) fits in the garage in the > pole's own frame. If you disagree, can you point to a time index in the > video where he says this, or a time index in the first video where he says > the car fits in the garage in the car's frame? > > > >> * This is what one expect to show if the disagreement of the frames is >> the cause of the paradox, but apparently it isn't, and the disagreement >> about simultaneity alone is sufficient to resolve the paradox. This is what >> I am trying now to understand. AG* >> >> >> *And we agree it can fit from the pov of the garage frame, since the >> car's length contracts. So what are we arguing about is this; does the >> disagreement about fit constitute an objective fact and thus a paradox? AG* >> >> >> >> >> >> >> *What could be the meaning of "rest frame" associated with "garage"? I >> don't have a clue. Shall we consult Webster's Dictionary? As for my >> numerical example, I suggest you do the arithmetic, and if you don't get my >> prediction, I will concede the argument. AG * >> >> >> *Yeah, use 12' and 10' for the lengths of the car and garage respectively >> when at rest (which means no motion of car). Then using the LT determine >> how fast the car must be moving to contract the car's rest length to >> .000001' from the pov of the garage frame. Then place the car in the center >> of garage, and recognize how easily it fits (by any method of your choice). >> Now, from the pov of the car frame, and the speed of the car previously >> calculated, calculate the contracted length of the garage, and place the >> car at the center of the garage. Does the front of the car extend beyond >> the rear of the garage, whereas previously it did not? No need to worry >> about what "seeing" means in this comparison.* >> >> >> It’s critical that you specify if by “see” you are talking about what >> light signals are reaching their eyes at that point, or if you are talking >> about the coordinates they assign to front and back of car and garage at >> simultaneous moments in their own frames; the answer will be completely >> different depending on what you mean. If you are just talking about visual >> seeing, I can do that, but just be aware that most of the usual textbook >> equations of relativity including length contraction are *not* intended to >> address visual appearances. >> >> Jesse >> >> >> *Let's forget about "seeing" in these scenarios since I agree it >> unnecessarily complicates the analyses. I will go back to your post with my >> question marks and try to resolve as much as possible. However, I don't >> think we can resolve anything in these discussions, for this reasonaaaaa. I >> proposed a scenario where from the garage frame the car fits with ease, >> whereas from the car frame it fails to fit and in fact easily extends >> beyond the rear end of garage. I conjecture that your response will be that >> different frames give different measurements, so there's nothing >> particularly noteworthy about this situation, and it certainly doesn't >> amount to a paradox. This result concerning fitting or not can easily be >> concluded without any arithmetic. Is my conjecture about your response >> correct? AG* >> >> >> Sure, if we are talking about local measurements in each frame rather >> than visual seeing, I see no paradox in the fact that they disagree on the >> time order of the spacelike separated events A=“back of car passes front of >> garage” and B=“front of car passes back of garage” and therefore disagree >> on fitting. >> >> >> *In the example I posted, the frames disagree on fitting, and AFAICT >> there's nothing to suggest a disagreement on the time order of events. In >> fact, what you claim doesn't seem physically impossible in either frame. >> Can you show me EXACTLY how you reached this conclusion, without referring >> to one of your other posts? It seems that you pulled that conclusion out of >> the preverbial hat. AG* >> >> >> You can easily just look at the times of events in either Brent’s >> numerical example or mine to see the two frames disagree on the order of >> the two events I keep bringing up, A=“back of car passes front of garage” >> and B=“front of car reaches back of garage”. In my example, A and B happen >> simultaneously at t = 0 in the garage frame, while in the car frame B >> happens at t’ = -15, which is before the time when A happens in the car >> frame at t’ = 0. >> >> And isn’t it obvious that if some frame says that B happens before A, >> meaning the front of the car reaches the back of the garage before the back >> of the car has yet entered the front of the garage, then that’s equivalent >> to the statement that in that frame the car doesn’t fit, whereas in a frame >> where A happens before B or simultaneously with it, the car does fit in >> that frame? >> >> This is one of the most basic aspects of analyzing the problem that we’ve >> talked about over and over, and you’ve previously agreed to, I don’t >> understand why there’s be any confusion here. >> >> >> *Your memory is in error. I never agreed to that. * >> >> >> Yes you did! See our discussion at >> https://groups.google.com/g/everything-list/c/gbOE5B-7a6g/m/B15IG50SAQAJ >> where I was responding to your previous comment at "I haven't thought about >> ordering", and I said the following: >> >> "You haven't thought about it?? Disagreement about the ordering of these >> two specific events (due to differences in simultaneity) is what Brent and >> I have both been emphasizing as the fundamental resolution of the paradox, >> have you not even understood that this is central to what we are arguing, >> and considered in an open-minded way whether or not it makes sense? >> >> >> *As I think I posted, I don't understand the argument that disagreement >> about simultaneity resolves the paradox. This is surely the standard >> alleged solution, but using the LT and length contraction, I seem to get a >> paradox if we assume disagreement about fitting is the cause of the >> paradox. You claim time-ordering shows the car can't fit. This is my >> conclusion using length contraction, whiich seems simpler. So, our >> disagreement of the resolution apparently has nothing to do with whether >> the car fits from its frame, since we're in agreement that it does not. AG * >> >> >> No, I wasn’t talking about the best way to understand or explain why the >> car doesn’t fit, I was just talking about logical equivalence. But as I >> have said elsewhere, an analysis of relativity of simultaneity is needed >> conceptually if you want to answer the *separate* question “given that >> different frames disagree about whether the car fits, how can we avoid the >> conclusion that they must disagree in their predictions about local >> physical facts?” >> >> >> If you don't see why the ordering of these two events is considered >> equivalent to the question of fitting, consider a simpler classical >> scenario where everyone agrees about simultaneity and length. A car is >> passing through a covered bridge, and we are observing it in a side view >> with the car driving from left to right, so the front of the car begins to >> disappear from view under the bridge as soon as it passes the left end of >> the bridge, and begins to re-emerge into view as soon as it passes the >> right end of the bridge. Would you agree in *this* scenario, if the back of >> the car disappears from view on the left end before the front of the car >> emerges into view on the right end, that means for some time the car was >> fully hidden under the covered bridge, meaning it "fit" inside? And would >> you likewise agree that if the front of the car starts to emerge from view >> on the right end before the back of the car has disappeared from view on >> the left end (say it's a very short covered bridge and the car is a stretch >> limo), so there was never a time when the car was fully obscured from view >> by the covered bridge, that means the car did *not* fit inside?" >> >> >> *I'm not sure. I have to think about this some more. Why can't we just >> stick to lengths? AG * >> > > You could at least ask some questions about whatever is puzzling you > rather than just avoiding the subject by switching to exclusive talk about > length. Remember, this is a purely classical scenario, no tricky issues of > length contraction or simultaneity. Classically, if we have an 18-foot long > limousine driving through a covered bridge that's only 6 feet wide, and > you're watching from the side with the limousine moving left to right, are > you genuinely unsure about whether you'll see the front of the limousine > poke out of the right side of the covered bridge BEFORE or AFTER the back > of the limousine first disappears behind the left side of the covered > bridge? If the front didn't poke out from behind the right side of the > covered bridge until AFTER the back disappeared behind the left side, that > would mean there was some period of time where the 18-foot limousine was > wholly obscured from view behind the 6-foot covered bridge, which doesn't > make a lot of sense geometrically. > > Jesse > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/d/msgid/everything-list/CAPCWU3LmnZWN-EFizPhqRimjTdn9%2Bqr8N61KyZ9sgmV15Xv9KA%40mail.gmail.com > <https://groups.google.com/d/msgid/everything-list/CAPCWU3LmnZWN-EFizPhqRimjTdn9%2Bqr8N61KyZ9sgmV15Xv9KA%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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