On 4/6/22 12:22 PM, Richard Livingston wrote:
>
> What myself and others have been trying to get you (Mike Fontenot)
> to understand is that the acceleration of the observer does not actually
> change anything about the distant twin.
It's not clear what that statement even MEANS. Obviously, the distant
twin (she) doesn't suddenly feel like she's getting younger. At each
instant in her life, her brain is in a state that is different from all
of her other brain states. Nothing can change those states. But the
accelerating observer DOES conclude that she instantaneously gets
younger when he instantaneously changes his velocity in the direction
away from her. And so, FOR HIM, she ACTUALLY gets younger. All
perpetually-inertial observers disagree with him about her getting
younger when he instantaneously changes his velocity, but they also all
disagree among themselves about what her current age is when the
accelerating observer changes his velocity. And FOR EACH OF THEM, she
ACTUALLY has the current age they compute. That's just the way special
relativity IS ... different observers disagree, they all think they are
right, and none of them is wrong!
What is really new, though, in my latest results, is the fact that the
accelerating observer can assemble an array of clocks (and attending
"helper friends" (HF's)), which give him a "NOW" that extends throughout
all space (analogous to what Einstein did for inertial observers). And
THAT guarantees that the accelerating observer's conclusions about the
home twin's age are fully MEANINGFUL to him. His conclusions agree with
the CMIF simultaneity method, which means that the CMIF simultaneity
method is the only correct simultaneity method.
[[Mod. note -- I think you're mistaken in a couple of places:
1. An accelerating obserer ("he") does not (or to be pedantic, should
not, if he is doing physics correctly) conclude that the distant twin
("she") instantaneously gets younger when he instantaneously changes
his velocity in the direction away from her. Rather he concludes
that her age coordinate in inertial reference frame #2 (after his
velocity change) < her age coordinate in inertial reference frame #1
(before his velocity change). But these are two DIFFERENT inertial
reference frames, with DIFFERENT time coordinates. Attributing
physical meaning to a comparison between DIFFERENT inertial frame's
time coordinates is no more valid than (say) attributing physical
meaning to the difference between 2022 (the current year on Earth
in the Gregorian calendar) and 4720 (the current year on Earth in
the Chinese calendar). If I install new calendar software on my
computer, I don't suddenly get 4720-2022 years younger or older for
any sensible meaning of "younger" or "older". :)
2. What does it mean to say a time coordinate is "physically meaningful"?
I would argue that it means that you can write the laws of physics
in a sensible form in terms of that time coordinate. So, what would
(say) Newton's 2nd law look like using the CMIF time coordinate of
an accelerating observer? Ick, not nice at all. Or how about Maxwell's
equations? Or even something very simple like the radioactive decay
law
N_atoms(t) = N_atoms(0) * exp(-lambda*t)
for a fixed lambda. Again, not nice at all if "t" on the left-hand
side and "t" on the right-hand-side are the time coordinate of different
inertial frames.
The fact that these and other laws of physics don't have a sensible
form when written in a mixture of different time coordinates (such
as CMIF times for accelerating observers) is, I would argue, prima
facie evidence that such a mixture of time coordinates is *not*
physically meaningful.
3. You write that "the CMIF simultaneity method is the only correct
simultaneity method". But this begs the question of how to define
"correct". There are other ways of doing distant clock synchronization
which differ from Einstein synchronization (e.g., slow (adiabatic)
clock transport, which gives a different synchronization result
for each choice of the inertial reference frame in which the clock
transport is "slow").
[That is, suppose we are at (fixed) position A in some inertial
reference frame F0, and set a (gedanken) ideal clock M to match
our A clock. Then we transport M at velocity v << c to some
other (fixed) position B a distance d away in this same inertial
reference frame F0. This takes a time d/v. Since M's Lorentz
time Lorentz time dialation factor is quadratic in v (for v << c),
the accumulated time dialation effect on effect on M's clock
by the time M arrives at B is linear in v, and hence can be
made arbitrarily small by choosing v small enough (and waiting
long enough for M to arrive at B). Then when M (eventually)
arrives at B, we set B's clock to M's reading.
This defines the "slow clock transport" clock synchronization
scheme.
The interesting -- and slightly counterintuitive -- thing is
that if we observe this entire process from some other inertial
reference frame F1 which is moving (along the A-B direction)
with respect to our original inertial reference frame F0, and
use F1's definition of "slow motion", then it turns out that
we'll get a *different* clock synchronization.]
Can you point to a law of physics which specifically picks out
Einstein synchronization as "correct" and other synchronizations
as "incorrect"? If not, what basis do we have for saying that
one of these is "correct".
-- jt]]