On Friday, January 24, 2025 at 10:29:03 PM UTC-7 Brent Meeker wrote:
On 1/24/2025 5:06 PM, Alan Grayson wrote:
On Friday, January 24, 2025 at 2:21:43 PM UTC-7 Jesse Mazer wrote:
On Fri, Jan 24, 2025 at 4:04 PM Alan Grayson <[email protected]> wrote:
On Friday, January 24, 2025 at 10:41:45 AM UTC-7 Jesse Mazer wrote:
On Fri, Jan 24, 2025 at 8:53 AM Alan Grayson <[email protected]> wrote:
On Thursday, January 23, 2025 at 11:46:46 PM UTC-7 Brent Meeker wrote:
That's exactly what my diagram shows. Didn't you look at it?
Brent
Sure, I looked at it but I prefer text, and I forgot you're a deaf mute.
And NO, I didn't know that frame transformations can invert time
relations. Let's forget it. I forgot you prefer your riddles. Grade C- . AG
The point that the LT can change the order of events with a spacelike
separation is one I also talked about many times on the previous thread,
for example at
https://groups.google.com/g/everything-list/c/vcrAzg4HSSc/m/knVuCxHFAwAJ
where I wrote: "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." Likewise in
https://groups.google.com/g/everything-list/c/gbOE5B-7a6g/m/MwKDuJM-AQAJ
where I wrote: "Do you understand that when people talk about the
relativity of simultaneity in the context of the car/garage problem, they
are referring not just to events which are actually simultaneous in some
frame, but also the fact that different frames can disagree about the
time-ordering of events with a spacelike separation (i.e. neither event is
in the past or future light cone of the other event)? The events A and B I
was talking about earlier are not simultaneous in either the car frame or
the garage frame (at least not with the numerical values for rest lengths
and relative velocity given by Brent), but they happen in a different order
in the two frames, and the relativity of simultaneity is key to
understanding how that's possible, in Newtonian physics where all inertial
frames agree about simultaneity there could be no disagreement about the
order of any events."
Brent has made this point in the past as well, for example at
https://groups.google.com/g/everything-list/c/gbOE5B-7a6g/m/WcxkopmjAAAJ
where he wrote: "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."
Did you really not remember any of these discussions, or did you just
misunderstand the meaning of "invert time relations" to be something
different than the idea that two events A and B with a spacelike separation
can have a different time-order in different frames?
Of course I recall, but I haven't had time to research the issue, such as
why the frames in the problem are, or might be, spacelike separated. AG
Frames have no specific location, they are coordinate systems covering all
of spacetime, so it doesn't make sense to say *frames* can be spacelike
separated.
*Right. I was skeptical about what I wrote, when I wrote it. OTOH, since
EVENTS can be spacelike separated, I don't see any such events in this
problem. For example, the ends of the car aren't spacelike separated;
neither are the ends of the garage. If Brent weren't a failing teacher of
SR, he would specify what he means. I am in no mood to guess his meaning.
AG*
*You mean you just want to keep trolling Jesse. Brent*
*No. Of course not. All your education, but in the final analysis, when it
comes to teaching SR, you're a worthless, insulting prick. Jesse uses text,
and I find it very useful. Jesse; hold up on your posts while I catch up.
AG *
It's pairs of points in spacetime, or equivalently pairs of local physical
events occuring at each point (like the event of the back of the car
passing the entrance of the garage vs. the event of the front of the car
reaching the back of the garage), that can be spacelike separated. 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). For any two such
points/events A and B with a spacelike separation, you can always find some
frames where A occurs before B and other frames where B occurs before A,
that's something that can be derived from the Lorentz transformation
equations.
Jesse
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