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"Veritasium" (YT) - "The Big Misconception About Electricity" ?

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SiliconWizard:
So do photons have a mass anyway? :popcorn:

TimFox:
Here is a summary of further work on the time dilation experiment:  from https://www.physicsforums.com/threads/a-g-kelly-and-his-criticism-of-relativity.371910/

"No. Certain internet kooks, including someone named A.G. Kelly, have produced reanalyses of the Hafele-Keating data[Hafele 1972] in an attempt to disprove relativity. This is just silly, because the experiment was reproduced four years later to much better precision,[Reisse 1976,Williams 1976] and again in a 25th-anniversary reenactment. The GPS system depends on general relativity, so any time you use a GPS receiver, you're reproducing relativistic time dilations of the type seen by Hafele and Keating.[Ashby 2003]

Hafele and Keating, "Around the world atomic clocks:predicted relativistic time gains," Science 177 (1972) 166.

Hafele and Keating, "Around the world atomic clocks:observed relativistic time gains". Science 177 (1972) 168.

R.A. Reisse, "The Effects of Gravitational Potential on Atomic Clocks as Observed With a Laser Pulse Time Transfer System," University of Maryland Ph.D. dissertation (May, 1976).

R.E. Williams, "A Direct Measurement of the Relativistic Effects of Gravitational Potential on the Rates of Atomic Clocks Flown in an Aircraft," University of Maryland Ph.D. dissertation (May, 1976).

C. Alley, "Proper Time Experiments in Gravitational Fields with Atomic Clocks, Aircraft, and Laser Light Pulses," in Quantum Optics, Experimental Gravity, and Measurement Theory, eds. Pierre Meystre and Marlan O. Scully, Proceedings Conf. Bad Windsheim 1981, Plenum Press, New York, 1983, ISBN 0-306-41354-X, pp. 363–427. This is available online and gives a summary of Reisse and Williams' dissertations.

Ashby, "Relativity in the Global Positioning System," http://www.livingreviews.org/lrr-2003-1  "

As is typical with scientific progress, an initial interesting experimental result is retried in later years with better equipment to see if it stands up.

aetherist:

--- Quote from: TimFox on February 27, 2022, 10:34:36 pm ---Here is a summary of further work on the time dilation experiment:  from https://www.physicsforums.com/threads/a-g-kelly-and-his-criticism-of-relativity.371910/

"No. Certain internet kooks, including someone named A.G. Kelly, have produced reanalyses of the Hafele-Keating data[Hafele 1972] in an attempt to disprove relativity. This is just silly, because the experiment was reproduced four years later to much better precision,[Reisse 1976,Williams 1976] and again in a 25th-anniversary reenactment. The GPS system depends on general relativity, so any time you use a GPS receiver, you're reproducing relativistic time dilations of the type seen by Hafele and Keating.[Ashby 2003]

Hafele and Keating, "Around the world atomic clocks:predicted relativistic time gains," Science 177 (1972) 166.

Hafele and Keating, "Around the world atomic clocks:observed relativistic time gains". Science 177 (1972) 168.

R.A. Reisse, "The Effects of Gravitational Potential on Atomic Clocks as Observed With a Laser Pulse Time Transfer System," University of Maryland Ph.D. dissertation (May, 1976).

R.E. Williams, "A Direct Measurement of the Relativistic Effects of Gravitational Potential on the Rates of Atomic Clocks Flown in an Aircraft," University of Maryland Ph.D. dissertation (May, 1976).

C. Alley, "Proper Time Experiments in Gravitational Fields with Atomic Clocks, Aircraft, and Laser Light Pulses," in Quantum Optics, Experimental Gravity, and Measurement Theory, eds. Pierre Meystre and Marlan O. Scully, Proceedings Conf. Bad Windsheim 1981, Plenum Press, New York, 1983, ISBN 0-306-41354-X, pp. 363–427. This is available online and gives a summary of Reisse and Williams' dissertations.

Ashby, "Relativity in the Global Positioning System," http://www.livingreviews.org/lrr-2003-1  "

As is typical with scientific progress, an initial interesting experimental result is retried in later years with better equipment to see if it stands up.

--- End quote ---
Thanx for thems links. I will have a read & get back, but will take time.
I might be familiar with all of thems, i used to read all of that stuff.
Ashby i remember invokes some peculiar kind of Sagnac Effect.
GPS disproves time dilation. However there are certain aspects of GTR that are supported by atomic clocks at altitude in the lab & on nearby hills. I have a theory re that (naturally).

TimFox:
The final reference in that post gives a detailed mathematical description of the operation of GPS, using relativity.
You may enjoy the equations.  Eq. 19 gives a calculation for a 7 parts in 1010 correction due to motion, which is about 104x higher than the uncertainty in modern cesium clocks.

Further down in the paper, we have this interesting historical note:

"There is an interesting story about this frequency offset. At the time of launch of the NTS-2 satellite (23 June 1977), which contained the first Cesium atomic clock to be placed in orbit, it was recognized that orbiting clocks would require a relativistic correction, but there was uncertainty as to its magnitude as well as its sign. Indeed, there were some who doubted that relativistic effects were truths that would need to be incorporated [5]! A frequency synthesizer was built into the satellite clock system so that after launch, if in fact the rate of the clock in its final orbit was that predicted by general relativity, then the synthesizer could be turned on, bringing the clock to the coordinate rate necessary for operation. After the Cesium clock was turned on in NTS-2, it was operated for about 20 days to measure its clock rate before turning on the synthesizer [11]. The frequency measured during that interval was +442.5 parts in 1012 compared to clocks on the ground, while general relativity predicted +446.5 parts in 1012. The difference was well within the accuracy capabilities of the orbiting clock. This then gave about a 1% verification of the combined second-order Doppler and gravitational frequency shift effects for a clock at 4.2 earth radii."

And don't forget the muons!  For example, see  https://hal.archives-ouvertes.fr/hal-02531926/document

aetherist:

--- Quote from: SiliconWizard on February 27, 2022, 10:33:24 pm ---So do photons have a mass anyway? :popcorn:

--- End quote ---
Yes photons have mass. Everything has mass (except gravity), koz everything is made of photons, photons are the fundamental building block of the universe.
It’s a bit off topic re the Veritasium gedanken, but not really, koz everything affects everything. But here goes.
Photons are an excitation (vibration)(spin) & annihilation of aether. This annihilation propagates through the aether at the speed of light (of course).
So in that sense a photon is a hole, that moves continuously.
Aether flows in to replace the lost aether.
The acceleration of the aether inflow is what gives us the gravitational force. Accelerating aether accelerates particles & bodies etc that are in the aether.
The converse gives us inertia, ie inertial mass. Accelerating particles are resisted by the aether.
EM radiation too has mass. EM radiation is not made of photons, but is radiated by photons, it is a part of photons.

A free photon (eg light) is trapped in one dimension, it propagates at c in a straight line.
A semi-confined photon (eg an electon) is trapped in two dimensions, it propagates at c on a surface.
A confined photon (eg an electron) is trapped in three dimensions, it loops at c in a small volume.

Electrons & other elementary particles give us atoms etc.
But i dont believe that an electron is a hard little nut that orbits a nucleus. In fact i doubt that a nucleus exists. I prefer that an atom is a molecule of sorts (made up of alpha particles for the heavier elements).

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