On 12/10/2024 2:21 PM, Alan Grayson wrote:
On Tuesday, December 10, 2024 at 1:46:37 PM UTC-7 Brent Meeker wrote:
On 12/10/2024 1:33 AM, Alan Grayson wrote:
On Monday, December 9, 2024 at 4:54:34 PM UTC-7 Brent Meeker wrote:
On 12/9/2024 3:24 PM, Alan Grayson 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
Since the car's length can be assumed to be arbitrarily
small from the
pov of the garage, why worry about fitting the car in garage
perfectly,
and then appealing to difference in spontaneity to prove no
direct
contradiction between the frames? It seems like a foolish
effort to
avoid a contradition, when one clearly exists. AG
What's the contradiction?
The contradiction is precisely this; assuming the initial rest
state is that the length of the car is larger than the length of
the garage, we get the *car* *never fitting* in the garage from
the pov of the car, and the *car* *fitting* in the garage from
the pov of the garage. The car can't fit *and* not fit in the
garage.
You think that because you have not carefully defined "fit", which
does require reference to simultaneity.
I defined "fit" to mean the car's length in any frame is *less* than
the garage's length. AG
Wrong!
The former result is easy to see, since the car's motion shrinks
the garage's length, so the car, initially longer than the
garage, can never fit inside the garage.
Within the cars reference frame.
Yes. AG
The latter result follows from the fact that from the pov of the
garage, the car's length shrinks, and for a sufficient velocity,
it will shrink enough to fit in the garage. Further, the issue of
simultaneity is a non-issue,
No it is the essential issue. The car (or the garage) don't
actually undergo some physical shrinkage.
Yes. It's all about appearances, or so it seems.
No, it's all about measurements and simultaneity.
And yet, physicists claim the LT gives the actual measurements in one
frame, using the measurements in another frame. AG
If they did they wouldn't keep their dimensions in their own
frame. So it is a question of measurement and simultaneity.
Why then do physicists agree that the distance to Andromeda will be
immensely shortened if a traveler's velocity is close to c? Never a
mention of simultaneiry in this case. AG
Because they're not concerned with two events, just with the duration of
the trip. In this case you must consider two events: One when the front
of the car is adjacent to the exit of the garage and the other when the
rear of the car is adjacent to the entrance of the garage. If these two
events are spacelike relative to one another then there is a reference
frame in which they are simultaneous.
Brent
Brent
since measurements of the front and back end of the car occur in
the car's frame, and since the car never fits in the garage, such
measurements can never be made when the car perfectly fits in the
garage, or even loosely, since this condition never occurs. In
summary, I think I've done for relativity, what Bertrand Russell
did for Cantor's set theory; proving the existence of a
contradiction. AG
Brent
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