Jesse, he will *never* acknowledge anything... that will go on forever, this list is already dead because of that.
Le mar. 28 janv. 2025, 22:03, Alan Grayson <[email protected]> a écrit : > > > On Tuesday, January 28, 2025 at 1:37:33 PM UTC-7 Jesse Mazer wrote: > > On Tue, Jan 28, 2025 at 3:12 PM Alan Grayson <[email protected]> wrote: > > On Tuesday, January 28, 2025 at 11:37:54 AM UTC-7 Jesse Mazer wrote: > > On Tue, Jan 28, 2025 at 10:16 AM Alan Grayson <[email protected]> wrote: > > On Tuesday, January 28, 2025 at 7:28:08 AM UTC-7 Jesse Mazer wrote: > > On Tue, Jan 28, 2025 at 12:52 AM Alan Grayson <[email protected]> wrote: > > On Monday, January 27, 2025 at 10:24:41 PM UTC-7 Alan Grayson wrote: > > On Monday, January 27, 2025 at 8:45:32 PM UTC-7 Jesse Mazer wrote: > > On Mon, Jan 27, 2025 at 8:24 PM Alan Grayson <[email protected]> wrote: > > On Monday, January 27, 2025 at 4:46:07 PM UTC-7 Alan Grayson wrote: > > On Monday, January 27, 2025 at 1:15:05 PM UTC-7 Jesse Mazer wrote: > > On Mon, Jan 27, 2025 at 3:01 PM Alan Grayson <[email protected]> wrote: > > On Monday, January 27, 2025 at 12:54:57 PM UTC-7 Jesse Mazer wrote: > > On Mon, Jan 27, 2025 at 8:32 AM Alan Grayson <[email protected]> wrote: > > On Sunday, January 26, 2025 at 9:02:01 PM UTC-7 Jesse Mazer wrote: > > On Sun, Jan 26, 2025 at 10:23 PM Alan Grayson <[email protected]> wrote: > > On Sunday, January 26, 2025 at 9:13:54 AM UTC-7 Jesse Mazer wrote: > > On Sun, Jan 26, 2025 at 1:54 AM Alan Grayson <[email protected]> wrote: > > On Saturday, January 25, 2025 at 11:25:53 PM UTC-7 Brent Meeker wrote: > > On 1/25/2025 10:13 PM, Alan Grayson wrote: > > On Saturday, January 25, 2025 at 9:06:18 PM UTC-7 Brent Meeker wrote: > > On 1/25/2025 6:34 PM, Alan Grayson wrote: > > On Saturday, January 25, 2025 at 6:47:22 PM UTC-7 Jesse Mazer wrote: > > On Sat, Jan 25, 2025 at 8:07 PM Alan Grayson <[email protected]> > wrote: > > On Monday, December 9, 2024 at 2:01:28 PM UTC-7 Brent Meeker > wrote: > > > > > Nothing odd about dilation and contraction when you know its cause. > > But what is odd is the fact that each frame sees the result > > differently -- that the car fits in one frame, but not in the other -- > > and you see nothing odd about that, that there's no objective reality > > despite the symmetry. AG > > The facts are events in spacetime. There's an event F at which the > front of the car is even with the exit of the garage and there's an > event R at which the rear of the car is even with the entrance to the > garage. If R is before F we say the car fitted in the garage. If R is > after F we say the car did not fit. But if F and R are spacelike, then > there is no fact of the matter about their time order. The time order > will depend on the state of motion. > > Brent > > Jesse; it's the last two of Brent's sentences that I find ambiguous. What > does he mean? > > What about them do you find ambiguous? > > He's just saying that if there's a spacelike separation between the events > F and R (as there was in his numerical example), then you can find a frame > where R happens after F (as is true in the car frame where the car doesn't > fit), and another frame where F happens after R (as is true in the garage > frame where the car does fit). > > *What does he mean by "But if F and R are spacelike, then there is no > fact of the matter about their time order."? (What you wrote above?) * > > Brent writes > Yes. Just what Jesse wrote above. It means the two events > were so close together in time and distant in space that something would > have to travel faster than light to be at both of them. > > *More important I just realized that in the frame of car fitting, the > events F and R aren't simultaneous, so how does one apply disagreement on > simultaneity when one starts with two events which are NOT simultaneous? AG* > > Brent writes > That's why you should talk about events being > spacelike...the relativistic analogue of simultaneous. > > *I'd like to do that. BUT if the Parking Paradox is allegedly solved by > star**ting in the garage frame where the car fits, the pair of events > which define fitting are not spacelike since they occur at different > times! * > > You didn't read the definition of "spacelike" that I wrote above. You > want everything fed to you in tiny bites of knowledge which you forget > eight lines later, so the questions start all over again. > > Brent > > > *I read it, but didn't like it. Big difference. Maybe you should stop > trying to read my intentions. You may be smart, but reading my intentions > is way above your pay grade. How could two events with the same time > coordinate be referred as "so close together". Moreover, in all discussions > of solutions to the paradox, events that are simultaneous in one frame, are > shown not simultaneous in another frame. This being the case, the two > events of the car fitting in garage frame are simply NOT simultaneous! > Also, Jesse seems to be referring to different events than the ones you > refer to. So there's a muddle IMO. As a teacher, your preferred method is > to intimidate students. Grade now D+. AG * > > > Why do you think I am referring to different events? I referred to the > same events F and R that Brent did (F is the event of the front of the car > coinciding with the garage exit, R is the event of the rear of the car > coinciding with the garage entrance). > > If you don't like Brent's verbal explanation, I also gave you a > mathematical definition of "spacelike separation" in two recent posts on > the "Brent on Parking Paradox" thread at > https://groups.google.com/g/everything-list/c/QgVdhXi3Hdc/m/KC2lIKyrDQAJ > and > https://groups.google.com/g/everything-list/c/QgVdhXi3Hdc/m/FF7TpbG-DQAJ > -- "If you know the distance x and time interval t between the two > points/events in the coordinates of any inertial frame, to say they are > spacelike separated just means that x > ct (and an equivalent definition is > that neither point is in the past or future light cone of the other one)". > Since I explicitly referred to a time interval t between the two events, if > you had paid attention to that you would have known not to say "the pair of > events which define fitting are not spacelike since they occur at different > times". > > Jesse > > > *Yes, you defined spacelike separation, but without specific numbers for > events, one cannot automatically claim two events are spacelike separated. > Same goes for fitting in garage frame. I wasn't sure that all pairs of > events in garage where car fits are spacelike separated. And sometimes I > haven't caught up with your posts so I seem like I can't remember. And > occasionally I do forget what someone posted. AG* > > > I was responding to your statement "the pair of events which define > fitting are not spacelike since they occur at different times", one doesn't > need any specific coordinates to see that this statement is wrong because > it suggests spacelike separated events can't occur at different times. If > you hadn't read my definition or didn't remember it, fine. > > > *I meant above that I needed all the coordinate values to determine if two > events are spacelike separated; the time coordinates are not enough. AG * > > > I gave you both x and t coordinates for F and R in my last message, see > below. Or when you say "I meant above that I needed all the coordinate > values", is "above" referring to your original comment "the pair of events > which define fitting are not spacelike since they occur at different > times", i.e. are you saying that when you wrote that, what you really meant > was just that Brent hadn't provided the coordinates or R and F? Or would > you acknowledge that when you wrote that you were misunderstanding the > notion of spacelike separation? > > > I was referring to my original comment. I didn't misunderstand what > spacelike separation means. I don't recall what Brent posted. AG > > > Then why did you make the definitive sounding statement "the pair of > events which define fitting are NOT SPACELIKE since they occur at different > times", rather than something more open-ended like "you haven't given the > coordinates for the pair of events which define fitting, so although those > events could be spacelike separated you haven't given enough info to > demonstrate that"? > > > *I was left with the last recollection / impression when you gave an > example of simultaneous event which were spacelike separated.* > > > So when you made the statement "the pair of events which define fitting > are not spacelike since they occur at different times", you *were* thinking > that spacelike separation required the events to be simultaneous, even if > you corrected that error later? > > > *Yes. A long long time ago, on a galaxy far far away, I knew the > definition of spacelike separated. Later, in our discussions. temporarily > confused it with timelike separated. But when you used a sufficient > condition, that the events are simultaneous -- not the necessary condition, > that all coordinates must be applied, the former sufficient condition > temporarily stuck in my mind. Hence, my incorrect statement which I later > corrected. AG * > > > > * Then when I considered it further, I realized I needed all the > coordinates to make that assertion. As for Brent, as I recall, he didn't > give any coordinates, just the claim as an approximation. FWIW, the car > parking paradox reminds me of the S cat scenario, where S proved that a > superposition of alive and dead when the box is closed, cannot imply the > cat is alive and dead simultaneously. In a post here, I showed why a > superposition cannot be interpreted that way because of the infinitely many > bases for a system in Hilbert Space. In this problem, on relativity, > although I accept that different frames can make different measurement due > to relative motion,such as for E and B fields, the same car that can fit > and not fit, albeit at different times, seems a bridge too far. If I am > right, I can't say exactly what's wrong with relativity. It's a work in > progress. AG* > > > it seems like you're just coming up with an interpretation in retrospect > to avoid acknowledging you were wrong, > > > *I didn't use the word "wrong", but I clearly corrected my error. Why > isn't that enough for you? AG* > > > You seemed to be claiming you hadn't made an error at all in your original > comment, when you said above "I was referring to my original comment. I > didn't misunderstand what spacelike separation means". That was the post > that bugged me because it seemed like you were trying to say you understood > what spacelike meant all along, if you acknowledge you did misunderstand > what spacelike separation meant but later corrected the error, that would > be enough for me. > > > > *CORRECTION OF TYPOS IN CAPS:* > *Now I can't recall what "original comment" I was referring to.* > > > Just review that comment thread above, I had said: > > 'Or when you say "I meant above that I needed all the coordinate values", > is "above" referring to your ORIGINAL COMMENT "the pair of events which > define fitting are not spacelike since they occur at different times" ...?' > > And you replied: > > 'I was referring to my original comment. I didn't misunderstand what > spacelike separation means.' > > So, I assume the "original comment" was the one I had referred to where > you said "the pair of events which define fitting are not spacelike since > they occur at different times" > > > * I can say that all along I knew WHAT **s**pacelike separated means, > even if IT was temporarily subliminal.* > > > What was your understanding of what it meant? Your comment about timelike > separation below might indicate you still have some confusion about it, see > my reply. > > > > * In any event, you can and should be assured, that I am not trying to > deceive you or anyone, My time is too valuable to do that. Nor would I, > even if I had infinite time. AG * > > > > rather than accurately remembering/describing what you meant at the time. > (In general you never seem to acknowledge you were wrong about any > significant assertion you make concerning relativity, like with > your earlier claim the LT sometimes give different coordinates than what's > actually measured in a given frame, which you seem to have just dropped > rather than acknowledging any flaw in your argument) > > > *On that point, I am still not convinced the LT does what you claim. I was > planning to come back to that issue. I have to review why I thought that. > AG * > > > *I recall my doubts about your interpretation of the LT. It has to do with > length contraction and time dilation. The LT gives a result which isn't > reproduced in the target frame of the transformation. IOW, an observer in > the target frame doesn't notice (or measure) length contraction and time > dilation. AG* > > > But if you use the LT to transform into a "target frame" where an object > has a velocity of zero (like the rod in your earlier example), the LT > doesn't *predict* any time dilation or length contraction of the object in > that frame, that's what I told you repeatedly > > > *We agree. If the relative velocity is zero, the LT doesn't predict time > dilation or length contraction, but it does for velocity not zero. AG* > > > When you say "the relative velocity", the velocity of what relative to > what? When I said "a 'target frame' where an object has a velocity of zero" > I was referring to the velocity of the object in the coordinates of the > target frame, is that the same velocity you're referring to when you talk > about a "relative velocity" that can be zero or nonzero? > > > > > and then showed you explicitly with the numerical example involving the > rod at > https://groups.google.com/g/everything-list/c/ykkIYDL3mTg/m/giZVF9PpDQAJ > which you didn't reply to. You just keep repeating the same false claim > about what the LT predicts without addressing the counterarguments or > giving any calculations or argument of your own as to why *you* imagine the > LT predicts time dilation or length contraction of an object in the > object's own frame (apart from some sketchy argument you tried to make > involving GPS satellites which I addressed at > https://groups.google.com/g/everything-list/c/ykkIYDL3mTg/m/ximYgKzKDAAJ > ) > > > *In reply to your last question above; since you and others claim the LT > gives the results of what the target frame will actually measure, as > calculated from the source frame using the LT, I must include length > contraction and time dilation in those MEASUREMENTS. Numerical examples are > unnecesary in this case. AG* > > *When the relative velocity is not zero, the LT "predicts" time dilation > and length contraction, at least that's what every book or teacher of > relativity claims. But the target frame never measures this result,* > > > Again, if "relative velocity" means the velocity of the object in the > coordinates of the target frame, then if the object has a nonzero velocity > in the target frame (say a target frame where an object like a clock or rod > is moving at 0.8c), of course observers who are using *that* frame can > measure the length contraction/time dilation of the object, why would you > think otherwise? > > > *Because that's what every text and teacher of relativity say! An observer > in a moving frame as measured from a rest frame, does not perceive lengths > and times changed, whereas the observer in the rest frame using the LT does > observe this. There are formulas in SR to calculate these observations from > the pov of the frame doing the measuring. AG* > > > If on the other hand you are specifically imagining a "target frame" where > the object has zero coordinate velocity, i.e. the object's own frame (as > you were imagining in the previous discussion), then you are apparently > using "relative velocity" in a different way than I was, or maybe just > conflating different meanings without realizing what you're doing. > > > *I use v as in the gamma function. Do you know that that v is? The LT is > applied in a relative rest frame, observing a moving frame, and the moving > frame is what I call the target frame. In that frame, an observer cannot > measure or be aware of the time dilation and length contraction as measured > from the frame doing the measuring, which I call the source frame. You have > a different opinion that every text and teacher of relativity has. AG * > > > Let's just stick to your terminology of "source frame" and "target frame", > all the stuff about arbitrarily designating one frame as the "relative rest > frame" and calling the other the "moving frame" is the non-standard > terminology I've complained about which sometimes leads to verbal confusion > (for example in the earlier example with the Earth and the rod, if the > Earth has velocity zero in the source frame and the rod has velocity zero > in the target frame, it would be standard terminology to call the source > frame 'the Earth's rest frame' and the target frame 'the rod's rest frame', > so it can confuse things to try to designate just one of those frames as > 'THE relative rest frame'). And note that if we want to talk about the > length contraction or time dilation of some specific *object* like a rod, > we have to know the object's velocity in the source frame and the target > frame, there is no general rule that one of the two frames you use in the > LT has to be the object's own rest frame. Let's say we are talking about > measuring the length of a rod, and that v_rs is the velocity of the rod as > measured in the source frame, and v_rt is its velocity as measured in the > target frame. > > In your statement above about observers in the target frame not being > aware of the length contraction that was measured in the source frame, are > you assuming that v_rt = 0? If so, then my earlier comment can be rewritten > as: 'But if you use the LT to transform into a "target frame" where an > object has v_rt = 0 (like the rod in your earlier example), the LT doesn't > *predict* any time dilation or length contraction of the object in that > frame, that's what I told you repeatedly'. > > You responded with: 'We agree. If the relative velocity is zero, the LT > doesn't predict time dilation or length contraction, but it does for > velocity not zero. AG' > > But if "the relative velocity" in your comment refers not to v_rt but to > the relative velocity of the target frame and the source frame (the v that > appears in the Lorentz transform), then we are talking about different > things. And I definitely would *not* agree with a claim that the LT always > predicts we will observe length contraction of an object in the target > frame whenever the v that appears in the LT is nonzero: > > > *So the LT doesn't predict length contraction measurement in the target > frame.* > > > It depends on what specific object we are talking about, and what its > velocity is in the target frame. If we are talking about an object that has > v_rt = 0 in the target frame, it doesn't predict any length contraction of > *that* object in the target frame. > > * So what the hell are we arguing about? * > > > Your incorrect claim that there is a conflict between what the LT predicts > about the target frame and what is measured in the target frame. > > > *The LT doesn't do what you claimed it does; tell us, or PREDICTS, what > the target frame will MEASURE. AG* > > > That's just an empty assertion with no reasoning to back it up. If you > think my previous statement somehow supports it, you must have some basic > misunderstanding of what I wrote -- what I said was that for an object with > v_rt = 0, the LT predicts the object will have its MAXIMUM length in the > target frame, NOT be contracted, and measurements in the target frame would > match this prediction. If you think there is *any* scenario involving > inertial frames (not non-inertial coordinate systems like GPS) where LT's > prediction about the target frame doesn't match what's measured in the > target frame, please give at least some minimal details of what scenario > you are imagining (like the rod/Earth scenario), specifying the velocity of > the *object* in the target frame (like v_rt for the rod) separately from > the relative v between the two frames being related by the LT*.* > > > *All along you've claimed the LT predicts what is actually measured in the > target frame. Now you deny this, claiming it's just my empty assertion > without any reasoning to back it up. No way. I know what you've been > claiming all along -- that the LT tells us what is measured in the target > frame. It does NOT! AG* > > > > if v is nonzero but v_rt = 0, so the target frame is the object's rest > frame, then the LT predicts *no* length contraction of the rod in the > target frame, instead it predicts the rod will have its maximum length > (called its 'rest length' or 'proper length') in the target frame. That's > what I showed explicitly with the numerical example of the rod whose length > EXPANDED when going from the source frame (where it had nonzero velocity > v_rs) to the target frame (where it had v_rt = 0, i.e. the target frame was > the rod's own rest frame) at > https://groups.google.com/g/everything-list/c/ykkIYDL3mTg/m/giZVF9PpDQAJ > which you never responded to. > > Jesse > > > *When I asked Brent if the target frame of an LT measurement could detect > time dilation in its frame, IN THE TARGET FRAME, his reply was that it > measures ONE TICK PER SECOND; IOW no time dilation! Same presumably goes > for length contraction; not measureable in target frame. AG * > > > You'd have to specify the post so I can see the context, but I would > assume Brent was talking about a clock at rest in the target frame, i.e. > v_rt = 0. > > > *Yes. AG* > > So this would match what I told you above--if an object is at rest in the > target frame then THE LT DOES NOT PREDICT ANY LENGTH CONTRACTION/TIME > DILATION OF THAT OBJECT IN THE TARGET FRAME, so there is NO CONFLICT with > the fact that measurements of that object in the target frame will show no > length contraction/time dilation. > > > *But you claimed that the LT gives us what is measured in the target > frame, and I claimed it does not. Now you agree with me, but deny your > original claim. Just to be clear, the target frame is moving wrt the source > frame which is doing the measurement of length contraction and time > dilation. AG * > > > 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/79c0613c-70bd-4af8-8079-82c4dbdc06a8n%40googlegroups.com > <https://groups.google.com/d/msgid/everything-list/79c0613c-70bd-4af8-8079-82c4dbdc06a8n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- 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/CAMW2kAr%2Brd2FiT0-JrK0oR41Pfz-RyFzXKtvmjhNNL%3DO%2BRj%3DqQ%40mail.gmail.com.
