Le lun. 27 janv. 2025, 21:15, Jesse Mazer <[email protected]> a écrit :
> > > 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"? It seems like you're just coming up with an > interpretation in retrospect to avoid acknowledging you were wrong, 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) > What a farce, do you really expect he will acknowledge anything? Especially being wrong? 🙃 > > 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/CAPCWU3J1vc23uk0S_5WdGf8Q3qF0gj_Tg3HAFQnx0Vh%2B5_Bo7g%40mail.gmail.com > <https://groups.google.com/d/msgid/everything-list/CAPCWU3J1vc23uk0S_5WdGf8Q3qF0gj_Tg3HAFQnx0Vh%2B5_Bo7g%40mail.gmail.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/CAMW2kAqT61XdLHea7HHufu7cixat4kAiQC1XJg-XrWJhMhih3g%40mail.gmail.com.
