Post by LaurenceClarkCrossenPost by LaurenceClarkCrossen"It is obviously ridiculous to claim that "time itself" changes
because a clock changes. Clocks used in satellites are always
atomic clocks with precision one to 1E15 or better.
They _never_ change their rate due to change of altitude
or speed or anything else-
Atomic clocks don't change with gravity.
Nothing affects the rate of a _proper_ clock. It always run at
it's proper rate, advancing one second per second.
"Time dilation" doesn't mean that a clock has changed its rate."
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According to the European Space Agency, atomic clocks run faster in
space: "Einstein’s principle details how gravity interferes with time
and space. One of its most interesting manifestations is time dilation
due to gravity. This effect has been proven by comparing clocks at
different altitudes such as on mountains, in valleys and in space.
Clocks at higher altitude show time passes faster with respect to a
clock on the Earth surface as there is less gravity from Earth the
farther you are from our planet." -
https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration/
Research/Clocks_gravity_and_the_limits_of_relativity
And: "The NIST experiments focused on two scenarios predicted by
Einstein's theories of relativity. First, when two clocks are subjected
to unequal gravitational forces due to their different elevations above
the surface of the Earth, the higher clock—experiencing a smaller
gravitational force—runs faster." -
https://www.nist.gov/news-events/news/2010/09/nist-pair-aluminum-atomic-clocks-reveal-einsteins-relativity-personal-scale
The quotations above are not written by scientists, it is news
written by journalists who don't know what they are talking about.
I quote from your last reference:
"Scientists have known for decades that time passes faster
at higher elevations — a curious aspect of Einstein's theories
of relativity that previously has been measured by comparing
clocks on the Earth's surface and a high-flying rocket."
What does this mean?
Note that "clocks on the Earth's surface" will be synchronous with UTC.
Consider the following:
UTC is the coordinate time used in the non-rotating Earth centred
frame of reference (ECI-frame). Coordinate time is NOT proper time!
Given two satellites in circular orbit around the Earth.
Satellite A has the orbital time half a sidereal day measured in UTC.
Satellite B has the orbital time 1h 32m 37s measured in UTC.
Let t be the UTC-coordinate time of the satellite,
Let τ be the proper time of a clock in the satellite.
We then have: (according to GR, but experimentally verified)
Satellite A: dτ/dt = (1 + 4.4647e-10)
Satellite B: dτ/dt = (1 - 2.8411e-10)
Does this mean that according to GR,
the time in satellite A runs faster than time on Earth's surface?
Does this mean that according to GR,
the time in satellite B runs slower than time on Earth's surface?
Shouldn't it run faster?
Imagine you are in one of the satellites with no windows.
You have an atomic clock ticking out seconds as defined by SI.
Has it even any meaning to ask if your time runs faster
or slower than does time on the Earth?
Of course not.
Your clock runs at its proper rate, and advances one second
per second, neither your clock nor your pulse are affected of your
position in the universe, or your distance to the Earth or Sun
or the Andromeda galaxy, or your speed relative to anything.
You are weightless in a closed room, and nothing outside
that room can affect you in any way.
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But lets revert to satellite A for moment.
The orbital time of the satellite is:
Measured with UTC: 43082.045250000 s
The proper orbital time: 43082.045269235 s
(This is experimentally confirmed.)
The difference between the proper orbital time
and the orbital time measured by coordinate time in
the ECI frame is 19.235 μs.
This difference is often called "time dilation".
Which is a misnomer, no time is "dilated".
Clocks and thus "time" always run at their normal rate,
and advance a second per second.
Post by LaurenceClarkCrossenI agree that it is obviously ridiculous to claim time itself changes
because a clock changes. However, the ESA does just this in the above
quote.
You lied when you said, "Atomic clocks don't change with gravity."
You lied when you said, "They _never_ change their rate due to change of
altitude or speed or anything else-"
Nether I nor the scientists at ESA lied.
Some journalists trying to explain news about experiments
"lied" because they don't know better.
What GR say is not a matter of opinion, it is a matter of fact.
GR say that clocks always run at their proper rate.
Those who claim otherwise don't know GR.
--
Paul
https://paulba.no/