What causes an accelerated clock to record less events

[james fairclear]

TL;DR

What causes an accelerated clock to record less events

A clock is set up to continuously broadcast its indicated time via radio waves to non accelerating observers in different inertial frames of reference.

The clock is accelerated and its tick rate is observed to decrease by all observers relative to the tick rates of their local clocks. Its indicated time is lagging progressively behind the times indicated on the clocks of the observers. This is a real non-reversible observer-independent effect. Less events are recorded by the accelerated clock.

Is the accelerated clock recording less events than the observer clocks due to time literally flowing at a reduced rate in its inertial frame of reference or is there a physical explanation at the level of quantum events for this observation?

To my knowledge there is no evidence for the material existence of a time medium that physically flows at different rates. The definition of time in Physics is simply "that which is measured by clocks" which I take to mean a quantity of events (e.g. Caesium atoms between states) observed to be simultaneous with another quantity of events (e.g. a train passing between all the points on a station platform).

Einstein seems to take the same view stating "If we wish to describe the motion of a material point, we give the values of its co-ordinates as functions of the time. Now we must bear carefully in mind that a mathematical description of this kind has no physical meaning unless we are quite clear as to what we understand by “time.” We have to take into account that all our judgments in which time plays a part are always judgments of simultaneous events.".

What really is causing this actual reduction in the frequency of atomic transitions? Even if we consider that in the accelerated frame time flows more slowly there still has to be a physical explanation as to what causes time to flow more slowly and how the reduced flow of time interacts with quantum particles to reduce the quantity of quantum events.

 

[PeroK]

There is no "physical" cause. Spacetime has a four dimensional Minkowski geometry. That means that time isn't the absolute quantity you assume. The measured frequency of a cesium clock does not change in its own rest frame. The difference in general is due to a difference in elapsed time along the worldliness of each clock. This is not a mechanical or quantum mechanical effect.

 

[Ibix]

The clock is accelerated and its tick rate is observed to decrease by all observers relative to the tick rates of their local clocks.

No, only for frames that regard its velocity as increasing. Some frames will see its velocity initially decrease, and hence its tick rate increase. Note also that the observers may need to correct for the changing Doppler factor.

Is the accelerated clock recording less events than the observer clocks due to time literally flowing at a reduced rate in its inertial frame of reference or is there a physical explanation at the level of quantum events for this observation?

The accelerated clock does not have an inertial frame of reference - it is accelerating, so there is no inertial frame in which it is more than instantaneously at rest.

The physical explanation is quite simple if you look at it geometrically. Clock ticks measure out "interval" which is the Minkowski equivalent of distance. An inertial clock measures one second along its worldline between the 3d "surface" its inertial rest frame calls "now" and the 3d surface it calls "now" one second later. The accelerating clock does not follow the same shaped path as inertial clocks - it should not be surprising that the analogue of distance is not the same along this path as it is along the inertial clocks' paths.

So, in short, the answer is that it is pretty much the same as the reason why a straight line between two points and a curved line between the same two points do not have the same length.

 

[FactChecker]

TL;DR Summary: What causes an accelerated clock to record less events

A clock is set up to continuously broadcast its indicated time via radio waves to non accelerating observers in different inertial frames of reference.

The clock is accelerated and its tick rate is observed to decrease by all observers relative to the tick rates of their local clocks. Its indicated time is lagging progressively behind the times indicated on the clocks of the observers. This is a real non-reversible observer-independent effect. Less events are recorded by the accelerated clock.

Is the accelerated clock recording less events than the observer clocks due to time literally flowing at a reduced rate in its inertial frame of reference or is there a physical explanation at the level of quantum events for this observation?

Acceleration is an unnecessary (and distracting) complication. This same question could be asked about any clock in a relatively moving IRF. Wouldn't it be strange if the exact same slow-down were observed in ALL physical processes no matter how small (subatomic), large (orbiting planets), complicated (mechanical clocks), or simple (charged particles in linear accelerators)? Suppose you dream up a reason for one or two of them. Then you have to explain why they all give the exact same slow-down. The intuitive reason is that time itself has appeared (to an outside observer) to change.

Always remember that the slow-down is being observed by comparing two clocks, one at the start of the timing and one at the end of the timing, in widely separated locations of the observing IRF. The synchronization of the separated clocks is key. This is the problem of relativity of simultaneity.

 

[james fairclear]

Is it your view then that time is a physical medium that literally flows at different rates affecting clocks?

 

[james fairclear]

When you say that it is due to a difference in elapsed time is it your view then that time is a physical medium that literally flows at different rates affecting clocks?

 

[Ibix]

Is it your view then that time is a physical medium that literally flows at different rates affecting clocks?

No. That would be silly.

 

[FactChecker]

Is it your view then that time is a physical medium that literally flows at different rates affecting clocks?

There is no "flow of time". There is just the disagreement about how clocks in widely separated locations should be synchronized.

 

[PeterDonis]

The OP question has been answered, and the answers do not need any further repetition.

Thread closed.