Re: Feynman's Light Clock

Den 04.05.2025 20:42, skrev LaurenceClarkCrossen:

Feynman thought that time ran faster in higher gravity because his light
clock in a rocket ship ran faster the faster it accelerated. The light
flashes bounced from end to end.

No. Clocks don't run faster "in higher gravity".
Proper clocks are not affected by acceleration or gravitation.
Proper clocks always run at their proper rate.
And there is no such thing as a working "light clock". :-D

 Source: The Feynman Lectures on Physics Vol. II Ch. 42: Curved Space
https://www.feynmanlectures.caltech.edu/II_42.html
SEE FIGURE Fig. 42–17.A clock at the head of an accelerating rocket ship
appears to run faster than a clock at the tail.

Yes.
But the acceleration (and thus the 'gravitation') is the same in
the 'head' and 'tail' of the rocket.
There is no "higher gravity" in the 'head' compared to the 'tail'.
Let the proper acceleration of the rocket be a,
let the clock in the front be C1 and the clock in the back be C2.
Let d be the distance between the clock.
C is the speed of light in vacuum.
Let an inertial frame K(t,x)  be instantly co-moving
with the rocket when clock C1 and C2 show τ₁=0 and τ₂=0 respectively.
Let the t = 0 at the same instant.
The light that leaves C1 at the time t = 0, will hit C2
at the time t ≈ d/c. The speed of c2 in K will then be v ≈ ad/c.
Since the speed of C1 was 0 when the light was emitted,
C2 will measure the light to be Doppler shifted  by the factor
D ≈ (1 + v/c) ≈ (1 + ad/c²)
So the rate difference between the clocks is
  dτ₁/dτ₂ = (1 + ad/c²) or (dτ₁-dτ₂)/dτ₂ = ad/c².
Note that the difference in the gravitational potential
between C1 an C2 is ad.
Δf/f = (difference in gravitational potential)/c² = ad/c²

 He said that time would also run faster because all processes, such as
your heartbeat, would run faster.

In physics "time" is what clocks show.
There is no alternative to this definition.
https://paulba.no/pdf/Clock_rate.pdf

 Of course, now relativists say the opposite about GPS clocks:
Less gravity = faster clocks.

Nonsense.
It is the difference in the gravitational potential that
causes the apparent rate difference.
Gravitational potential =  - GM/r
If  r₁ is the radius of Earth and r₂ is the radius of GPS orbit,
the gravitational potential difference is:
  - GM/r₂ -(-GM/r₁) = GM(1/r₁-1/r₂)
Δf/f = (GM/c²)(1/r₁-1/r₂)  Note: this is the gravitational term.
The kinematic term must be added to get the rate of a clock
in GPS orbit.
The rest is gobbledegook.

 Then is it warranted to conclude from the rate of clocks that time
itself (all processes) changes?
 No. Clearly, it is not.
 Relativists now will say that atomic clocks are better than light
clocks, so we can judge by them.

"Light clocks"! Good grief!

 The clock's rate is only one process, so it cannot be equated to the
rate of time.
 This proves that if you have at least an 85 IQ and actually use it, you
are more intelligent than Einstein and his followers.

I think you have proved that you are not among those who have
at least an 85 IQ.
--
Paul
https://paulba.no/