jamesfairclear

Can I then consider the angular momentum of the electron to be an invariant quantity (like c) such that it will be the same value regardless of whether the body is relatively stationary on Earth or moving away from Earth at 0.99c?

Would you expect the quantity (the speed) of angular momentum to vary?

Considering an atom within a rigid body, does the angular momentum of an electron within the atom vary when the body is put in motion?

By relatively stationary I mean that the detector is for example on Earth at a location on the equator and the emitter is receding at a velocity v along the equator. It is of course a principal of SR that the speed of light is invariant but my interest is in finding experimental evidence of this invariance measured with a receding light source.

GPS supports the invariance of light speed in a given IFOR but not for a receding light source. I wouldn't agree that performing experiments in a single IFOR necessarily confirms the behaviour in multiple IFORs especially when we can already confirm that one property of light (the wavelength) behaves differently with a receding light source.

I don't doubt the mathematics. My interest is in finding experimental evidence to substantiate that light from a receding light source travels at c to a relatively stationary destination. Have you come across such an experiment?

It should work ok. The light source is set in motion at a constant speed S and then illuminated at a distance D from a relatively stationary detector. The illumination of the light source could either be triggered by coinciding with a relatively stationary device at distance D or via an onboard clock that calculates distance D. Thus we know exactly when the light source has travelled a distance D from the detector (t1) and the clock at the detector begins measuring time from that moment. Theoretically the one way speed of light is the same as the 2 way speed. However there has been a lot of debate about this over many years. I am specifically interested in measuring the speed of light from a receding light source. We know that the motion of the receding light source affects the wavelength of light received at a relatively stationary destination but I am looking for any experiments that have conclusively proven that it does not affect the speed of propagation. That is a interesting point. However I would have thought that the only potential issue would be extremely minimal doppler shift which probably wouldn't be sufficient for there to be any audible artefacts. Any variation from c of the speed of the radio waves reaching the car aerial would be insignificantly small to make any audible difference.

Thank you for your response. Your assumptions are correct. One could envisage an experiment whereby a light source is set in motion at a constant speed S and then illuminated at a distance D from a relatively stationary detector. A clock at the detector measures the time it takes the Doppler redshifted light to arrive from distance D in order to establish its speed. Are you aware of an experiment of this type that has explicitly measured the speed of Doppler redshifted light emitted from a receding light source?

My understanding is that Doppler redshifted light received at a relatively stationary destination from a receding light source is still deemed to be travelling at the same speed of c as light arriving from a relatively stationary source. Has this been experimentally verified and if so how?

There is a sequence of events counted by each clock. The clock itself cannot detect anything between each event because there is nothing to detect. Equally a human observer cannot detect anything between each event but can elect to assume notionally that there is an imaginary interval between events and characterise it as a flow of time even though there is nothing that can actually be observed. The alternate interpretation does not preclude making reference to Time for the sake of convenience. Thus we can refer to a measurement of 10 seconds or N events for a given observation. The alternate interpretation differs in that it proposes a different model substituting Time with a quantity of events. As previously stated the alternate interpretation is evidenced by any of the copious experiments that have substantiated Time Dilation. For example taking an atomic clock up in an aircraft , flying around the globe, returning to its starting point comparing its reading to that of a stationary clock located at the starting point. The difference in the readings substantiates that motion reduces the quantity of events.

This alternative interpretation is evidenced by the same evidence that substantiates Time Dilation in SR.

The notion of Time is a measurement of a quantity of events and an event cannot be undone. Thus the notional arrow of time can only be in one direction.

The sequence of events in the experiment is:

No. SR predicts that time dilates in a moving inertial frame of reference. This experiment can be interpreted as either substantiating Time Dilation or substantiating a reduction in the frequency of events. All calculations relating to Time dilation remain the same except that time is substituted with a relative Frequency of Quantum Events. Atomic clocks are highly predictable in that the decay events they count are highly predictable but significantly decay events are not totally predictable. Thus 2 atomic clocks side by side in the same stationary location will count very slightly differing numbers of events.

The experiment is done without making any assumptions about time. The numbers displayed on each clock are the numbers of decay events registered in the experiment. The numbers are tied to quantities of events not time and do not change arbitrarily.

You state "When you observe an elementary particle come into existence and then decay, you have observed an interval in time" No. You have only actually observed an elementary particle come into existence and then decay. If you had a clock running you could add that you observed further events being 2 ticks of the clock which you could choose to characterise as an interval of 2 seconds. You state "When you feel ordinary gravity holding you down, then this happens because of the principle of extremal ageing". No. The process of biological ageing is currently thought to be linked to free radicals. You state "When a photon gets frequency-shifted along a radial trajectory towards Earth, then this happens only because the spacetime manifold has a time dimension - this is as real as space, because without the time dimension, there would be no tidal gravity (the Weyl tensor vanishes identically in 1,2,3 dimensions). " You state "On a more direct level, we know from experiment and observation beyond any reasonable doubt that the world has local Lorentz invariance as a fundamental symmetry - which would of course not be possible if time wasn’t part of spacetime. So saying time is real, but denying that it is a geometric dimension within spacetime, is both physically and mathematically meaningless." These are both issues of terminology. Einstein famously characterised time as a 4th dimension but the label spacetime is really just a convenient way of describing a region of space along with its local gravitational field. Remember I am substituting the notion of time with relative frequency of quantum events (Rq) such that all calculations of trajectories will remain the same.

All that is required is to bring the clocks together such that a difference between the readings can be observed. The atomic clocks are instruments that count decay events of Cesium 133 atoms very accurately. So the clocks measure quantities of events. An arbitrary number of decays has been designated to represent 1 second of time. Perhaps you can elucidate?

The sequence of events is: 1. Synchronise clock A and Clock B in a given location at rest 2. Set clock A in motion 3. Move clock A back to the location of Clock B 4. Read the displays of both clocks The sequence of events using taps or clocks is: 1. Synchronise clock A and Clock B in a given location at rest 2. Set clock A in motion 3. Move clock A back to the location of Clock B 4. Read the displays of both clocks No steps have been left out. This is how copious such experiments have been done.

Ok to clarify the point we substitute the clock with a dripping tap. In the case of the moving tap we record 50 drips and in the case of the relatively stationary tap we record 100 drips. Again you can choose to explain the difference in the number of events by stating that time has slowed down for the moving tap. You state without any substantiation that "There’s no physical mechanism in play that could cause this". How do you conclude this? I could equally state that there is no physical mechanism in place to cause time to slow down. Einstein stated that Time must slow down in order to satisfy the equations without offering any explanation as to the underlying processes or substantiating the existence of time as a medium that is capable of slowing down. My postulation of a Relative Frequency of Quantum events between inertial frames of reference is not yet a detailed description of the underlying processes but is more specific than simply stating that Time slows down and is substantiated by the observational evidence that fewer atomic decays occur in a moving atomic clock than in a relatively stationary atomic clock. You bring the clocks to a given location and observe the values displayed on their respective displays. How is this relying on time in the experiment? Multiple highly accurate atomic clocks are tested to remain synchronous in a single inertial frame of reference and the experiment is repeated sufficiently to obtain accurate results.

You bring the clocks to a given location and observe the values displayed on their respective displays.

In an experiment with 2 atomic clocks where 1 clock is in motion relative to the other we observe fewer events occurring in the moving clock. We can interpret this observation as a slowing down of time for the moving clock. However the actual direct observation from countless experiments is that fewer events have occurred for the moving clock.

Thank you for your response. By Quantum events I mean any change of state of quantum particles such as momentum, radioactive decay and other related events that might influence decay We can detect some quantum events such as radioactive decay but to my knowledge not the events that give rise to decay We know from observations that quantum events (e.g. decay) are influenced by motion but we don't yet know why. One could propose that kinetic energy of a macro object inhibits the kinetic energy of its constituent quantum particles within the quantum space. The term I have used should be "Relative Speed" not "Relative Inertia" My point about clocks not being special is simply that it is not just clocks that slow down as a consequence of relative motion but all events in the moving inertial frame of reference. Length is a measurable property of one observable object with reference to another (ruler) whereas time is solely a notion that cannot be observed. Although length contraction is a predicted consequence of SR to my knowledge it remains contentious and has not been directly measured and thus I have not yet attempted to address length contraction but if it is real then I would expect it to be a related effect of a reduction in quantum events. Thank you for your response. I think terminology can get in the way of clarity. My definition of a Quantum event includes literally anything that may occur in the quantum space to cause a change in the energy of the local system. I would view a change in state as an event. On the assumption that for example radioactive decay of a quantum particle is influenced by the velocity of another quantum particle then we can predict that a reduction in the average velocity of quantum particles in a system will cause a reduction in the frequency of decay events. If we then observe a reduction in the frequency of decay events when we set an atomic clock in motion we can then propose a connection between its speed and a reduction in the average velocity of its constituent quantum particles which in turn gives rise to a reduction in the frequency of decay events As you say Time is a common parameter in Maths and Physics. My point is that Time is not something that can be observed and is best thought of as an imaginary interval between events. 60 ticks of a clock is most succinctly described as 60 events but is more convenient to describe as a minute of time.

A "Lifespan" could be described using the notion of time as 100 years or in terms of a quantity of events as 100 Earth revolutions around the sun. Either way the lifespan occurs and does not void my conclusion. I think an answer I gave to another comment was mistakenly linked to your comment!

Physics defines time as "that which is measured by clocks". It doesn't follow that something exists simply because you define it, you need to be able to observe it. I can define a unicorn as a horse with a single horn but that doesn't substantiate its existence. How do you conclude that time is a dimension or even that it exists without being able to observe it?

Time in physics From Wikipedia, the free encyclopedia Time in physics is defined by its measurement: time is what a clock reads.[