Mr. AG, read the f.....g name of the list. Le sam. 8 févr. 2025, 22:50, Alan Grayson <[email protected]> a écrit :
> > > On Saturday, February 8, 2025 at 2:08:05 AM UTC-7 Quentin Anciaux wrote: > > AG, what your thought experiment highlights is not a dichotomy in the > definition of the paradox, but rather a fundamental difference between > simultaneity-dependent contradictions and frame-dependent measurements in > relativity. > > 1. Why simultaneity matters in the original paradox > > The original paradox only appears when people assume there’s a universal > "at the same time" across both frames. > > Once we apply relativity of simultaneity, we see that each frame has its > own internally consistent timeline, resolving the contradiction. > > 2. Why spatial juxtaposition doesn’t create a paradox > > The observers at the midpoint are not measuring simultaneity-dependent > events, they are measuring spatial lengths, which are inherently > frame-dependent. > > There is no expectation in SR that two observers from different frames > must agree on length measurements—even if they occupy the same location in > space at a given moment. > > 3. Space and time are similar but not interchangeable > > Yes, spacetime diagrams treat space and time symmetrically in some > respects, but SR does not make space and time fully interchangeable. > > Time has an asymmetric role in causality (events in the past can influence > the future, but not vice versa), while space does not. > > This asymmetry means that disagreements in simultaneity lead to apparent > contradictions if misunderstood, while disagreements in spatial > measurements do not—because SR already accounts for them via length > contraction. > > 4. Your thought experiment is just a different way of looking at length > contraction > > The observer in the garage frame sees the car fitting, because in their > frame, the car is contracted. > > The observer in the car frame sees the car not fitting, because in their > frame, the garage is contracted. > > These are not "contradictory" observations, just different frame-dependent > measurements—exactly like time dilation or velocity-dependent mass. > > The original paradox relied on a false assumption of absolute > simultaneity—hence why simultaneity "resolves" it. > Your thought experiment doesn’t introduce a new paradox—it just reinforces > how relativity treats space and time differently and why length > contraction, like time dilation, is not paradoxical, just unintuitive. > > Quentin > > Hope this discussion about well known facts for about 120 years will end > and we can return to everything-list purposes. > > > Yeah, it's done, provided philosophical issues are excluded from "list > purposes". If you recall, Brent was insistent that in the context of the > paradox, there is no objective reality. This means, if anything, that the > results of SR are appearances, or just appearances, or mere appearances. > Resutls depend upon the frame of reference of observers, so there's no > problem if they're contradictory. OTOH, since clocks in the GPS system > experience measurable delays due to SR effects, its results surely seem > objectively real. But we can just toss that issue under the rug, as > "philosophy".and go on to "legitimate" list purposes, which exclude obvious > foundational issues which were not completely resolved in 1905. Included in > subjects which pass your test include arguments against frequentist > probability in QM because some probabilities are so small, they can't be > realized in the lifetime of the universe. DId it ever occur to you that > these unrealized probabilities might be the result of wf solutions that > extend infinitely in space and time? Have you noticed that the tails of > these wf's extend infinitely in time and space? Ignoring that, what is your > alleged solution; the MWI. Did it ever occur to you that at every > T-intersection, there is a countable set of outcomes for every turn, in > fact for any turn anywhere, by anything, including the common ant, the > multitude of species of flying insects. and prairie dogs whenever they look > around for predators? This is the foolishness you apparently endorse as > "list-purposes". What you apparetly prefer are non-interacting worlds, the > probability of each is indeterminate. And even on that single turn at any > intersection, you can't even explain how the sum of probabilites of a > countable set of outcomes can equal unity. In summary, IMO, you have a > self-serving view of the legitimate content of list purposes. AG > > > Le sam. 8 févr. 2025, 08:55, Alan Grayson <[email protected]> a écrit : > > > > On Thursday, February 6, 2025 at 2:23:45 PM UTC-7 Alan Grayson wrote: > > On Thursday, February 6, 2025 at 5:28:34 AM UTC-7 Quentin Anciaux wrote: > > AG, this is the closest you’ve come to an actual discussion, so I’ll give > you a straight answer. > > Your question boils down to whether simultaneity alone is enough to > resolve the paradox, or if there's still an issue when two observers, > co-located in space but in different frames, observe contradictory outcomes. > > Why Simultaneity Resolves the Paradox: > > 1. The "paradox" only exists if you expect a single, universal answer to > the question, "Does the car fit?"—which would require a preferred frame of > reference. But SR explicitly denies the existence of such a frame. > > > 2. Simultaneity isn’t just a technicality—it’s fundamental to how events > are ordered in each frame. In the garage frame, the car is fully inside at > one moment because simultaneity in that frame aligns the back entering and > the front still inside. In the car frame, simultaneity shifts, meaning by > the time the back enters, the front has already exited. The disagreement is > built into SR itself. > > Addressing Your "Co-Located Observers" Thought Experiment: > > You suggest that if two observers are spatially co-located but in > different frames, they would observe contradictory facts. But this is where > you’re making an error. > > 1. Frame membership matters: Each observer is still bound to their own > frame’s simultaneity rules. Just because they are momentarily at the same > point in space does not mean they share the same perception of simultaneity > or event ordering. > > > 2. Contradictory observations are expected, not paradoxical: In > relativity, observers in different frames frequently measure different > physical quantities for the same event (lengths, time intervals, etc.). > This is no different. The garage observer measures the car fitting because > their simultaneity rules allow it. The car observer measures it not fitting > because their simultaneity rules say otherwise. Each observer’s measurement > is internally consistent in their own frame—so there’s no contradiction > within SR. > > > 3. Would additional observers change anything? > No. Additional observers in each frame will confirm their own frame’s > version of events, reinforcing the idea that simultaneity dictates > different conclusions. There is no paradox because neither frame’s > measurement is "more real" than the other. > > The mistake is assuming that because two observers are momentarily > co-located, they must agree on event sequences. They do not. Their velocity > relative to each other still dictates their simultaneity slicing of > spacetime, and that’s what resolves the paradox. > > If you truly accept that simultaneity is relative and that SR allows for > frame-dependent measurements, then you should see why "fitting and not > fitting" is not a contradiction but a natural consequence of relativity. > > If you still think there’s a paradox, then ask yourself: what fundamental > assumption are you making that requires a single absolute answer to "Does > the car fit?" Because that’s where the actual mistake lies. > > Quentin > > > FWIW, I wasn't seeking to prove in this thought experiment that there's an > absolute answer to whether the car fits. In fact, I was alleging the > opposite, that with juxtaposed observers at the midpoint of the garage, the > car fits in one frame, and doesn't fit in the other. What I was alleging is > that this result seems curiously similar to the paradox when using "at the > same time" erroneously, whereas in this thought experiment only"same space" > is involved, not same time. AG > > > What this thought experiment shows is curious *dichotomy *concerning the > definition of the paradox. As long as it's assumed fitting and not fittling > occur at the same TIME, a "timely" form of juxtaposition, we have a paradox > (ostensibly resolved by the disagreement about simultaneity). But when > SPACE is juxtaposed, it's *not* considered a paradox. You'll note that in > the spacetime diagrams we have one dimension of time and one of space, > which have similar properties, albeit not identical. We also know that > given the initial condition, the car never fits from car's frame of > reference, and for a sufficient velocity, it will fit from the garage's > frame of reference. So the model of the spatial juxtapostion of the > observers at the halfway point in garage makes sense. AG > > > > Le jeu. 6 févr. 2025, 11:36, Alan Grayson <[email protected]> a écrit : > > > > On Wednesday, February 5, 2025 at 4:23:46 PM UTC-7 Alan Grayson wrote: > > On Wednesday, February 5, 2025 at 3:37:31 PM UTC-7 Quentin Anciaux wrote: > > AG, the fact that your only response is to repeat "PRICK" like a broken > record says everything about your inability to engage in actual discussion. > > > FWIW, we can engage in a rational discussion if you would cease making > accusations about my motives and state of mind. I've reviiewed some of your > earlier explanations of the alleged paradox, and your more or less constant > complaint that I downplay the role of simultaneity in the resolution. While > I admit that my initial proposed solution was mistaken -- that length > contraction was alone sufficient to resolve the paradox -- I still fail to > see why simultaneity does the trick. I say this because all it does is show > that fitting and not fitting cannot occur "at the same time". But once it's > acknowleged that each frame in SR has its own set of clocks, not > synchronized with the clocks in some other frame, the concept "at the same > time" is meaningless. So, if you agree so far, the question becomes whether > fitting and not fitting "at different times" remains a paradox to resolve. > Although, "at the same time" is meaningless, it's possible to imagine the > car midway within the garage, and two juxtaposed observers, one in each > frame, which observe the car fitting and not fitting, now NOT simultaneous, > but spatially co-located. Can this mean another form of the paradox is > alive and well, since each observer has contradictory observations (where > additional observers are added where necessary to confirm the > observations)? Although SR allows measurement to be frame dependent, why > isn't this stuation* essentially identical *to the one which requires > simutaneity arguments to allegedly resolve? AG > > -- > > 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/997c5736-cf45-482b-9511-2cccdc7a1b48n%40googlegroups.com > <https://groups.google.com/d/msgid/everything-list/997c5736-cf45-482b-9511-2cccdc7a1b48n%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/986b5bd9-7547-417a-b396-7797414ee9aen%40googlegroups.com > <https://groups.google.com/d/msgid/everything-list/986b5bd9-7547-417a-b396-7797414ee9aen%40googlegroups.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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