[jeffreyH]

We need time to see how fast things happen. Time is not a cause and has no effects. It can be affected by velocity. This is however a non local effect. Local time is always a constant.

[alancalverd]

Relativistic light shift always results in a redshift

Not true. The Pound-Rebka experiment shows a blue shift in one direction, red in the other.

[yor_on]

Chiral, keep on thinking
you're a gentleman, and a deep thinker.

Explore is what we do
Then we die :)

[chiralSPO (OP)]

Hi All, there is some great discussion here--and I will contribute to it more when I have gotten some answers from a friend who knows more about cosmology than I do! In the mean time, I noticed that this thread kinda went off on a tangent, so I have taken the liberty of splitting it here. Apologies, if there are relevant posts in the bit that I removed....

[jeffreyH]

I have been thinking about relativistic gamma in relation to this.

[jeffreyH]

I have been thinking about relativistic gamma in relation to this.

Since a time value of positive infinity can never be reached we never have a relativistic gamma value at 1. This ties into conservation of energy.

[Bogie_smiles]

I don’t want to appear to be discouraging. We do know for a fact that the quantification of time uses some form of clock, and we know that the rate that a clock measures the passing of time is affected by the relative acceleration of that clock vs some presumed rest clock.

Unfortunately there is no absolute space in which to place our rest clock, and so there is no absolute measure of time. Therefore, time is relative to conditions of local energy density set up by differences in gravitational potential, relative motion, and/or applied forces between two clocks in relative motion. The conditions of each clock in relative motion are therefore different.

I don’t see how you can get to anything fundamental in regard to a time increment from those circumstances, so I personally settle for the concept that time simply passes, but the measure of the rate that time passes is relative to the differing conditions in which our clocks are located.

On the bright side, maybe there is some fundamental increment of energy based on some foundational minimum background energy level. If such an energy level could not be reduced below this as yet unknown natural limit, and if we could place our rest clock there, maybe all other frames could be compared to that clock.

Is see the thread is revived, and the members have taken it in a couple of directions since the OP_, I have been reflecting on the topic, and on what I contributed earlier, and thought it wouldn’t hurt to add to my earlier reply.

I’ve revised my thinking beyond where I said, “I don’t see how you can get to anything fundamental in regard to a time increment from those circumstances…”

Actually, after coming back to the topic, I can hypothesize a circumstance where any two events that are separated in time and space can be reconciled to a given instant of time in a third frame of reference. A clock in that frame of reference would be in motion relative to the points in space and time where the two given events occur, and the frame would be identified by invoking the concept of the “simultaneity of relativity”.

It is a little complicated, and quite alternative, and off on another tangent, so I’ll simply say this for what it is worth: The moving point in space (the new frame of reference from which the two given events are seen to be occurring simultaneously) is a continual point of reference from which time is synchronized for those two events.

From that moving third frame of reference, any increment of time on a clock in that moving third frame could be considered fundamental relative to the two given events, given the application of the concept of the simultaneity of relativity.

If you can see that line of reasoning, then you might see that there is a point in space and time, relative to any set of two events, where there is an absolute increment of time passing relative to the two specific events. The concept can be applied to any two events, but the frame of reference containing the point in space and time from which absolute time is associated with each set of events would be unique.

So I would amend my \earlier statement to say that though there is no general absolute space and time, if you isolate any two events, there is a frame of reference where there is a time increment that is absolute for each unique set of events.



Edit: I should have ended this post with this explanation … If you turn around the concept of the relativity of simultaneity in your mind, it can become the concept of the simultaneity of relativity, and when you go there, you might be able to see that not even the absence of absolute time and space is absolute. This might be an unwelcome tangent in a thread in this sub-forum.


Edit 2
A further explanation of what is going on with the act of turning around the concept of the relativity of simultaneity:

When discussing the relativity of simultaneity, you are addressing the occurrence of one event that has two or more observers in different locations relative to the location of the event. The idea is that any two observers in separate locations will not observe the event simultaneously.

What I mean by “turning that around” is that you are addressing two (or more) events and finding a location relative to those two events that makes them seem to be occurring simultaneously. That location is what I call the third frame and it is any inertial frame where an observer would report that that the two separate events appeared to occur simultaneously.

[jeffreyH]

The problem with relativistic gamma is that it can't be applied in terms of velocity since here it is related to a ratio. I need to think this through in terms of expansion of the universe. It would make more sense related to frequency somehow. This is the problem with not thinking things through.

[Bogie_smiles]

One conclusion I am contemplating is that time is not fundamental in regard to the rate that it is measured to be passing on a given clock, because various changes will affect the rate that the clock will measure the passing of time. For example, if that clock is moved from location to location (accelerated/decelerated relative to the home conditions), or if the local conditions at the home location of the clock change relative to the original conditions, the clock will measure the passing of time at different rates.

[Bogie_smiles]

However, though the local conditions can be variable, in an environment where the conditions are constant, the rate that time would be measured to pass would be constant. That brings me to the conclusion that there is a fundamental aspect to time, which is that time will continually pass in any environment, in spite of the fact that the local conditions can affect the rate that time is perceived to be passing.

[Colin2B]

One conclusion I am contemplating is that time is not fundamental in regard to the rate that it is measured to be passing on a given clock, because various changes will affect the rate that the clock will measure the passing of time. For example, if that clock is moved from location to location (accelerated/decelerated relative to the home conditions),

No, the real problem is the other way round. The moving clock ticks at a constant rate (the fundamental time if you like), it is the other clocks (whether considering themselves at rest or moving) that measure that clock’s time as different to their own. Each clock records its own proper time as it moves along its worldline. So, the “various changes” do not “affect the rate that clock is measuring the passing of time” only the rate that other clocks measure it.

[Bogie_smiles]

No, the real problem is the other way round. The moving clock ticks at a constant rate (the fundamental time if you like), it is the other clocks (whether considering themselves at rest or moving) that measure that clock’s time as different to their own. Each clock records its own proper time as it moves along its worldline. So, the “various changes” do not “affect the rate that clock is measuring the passing of time” only the rate that other clocks measure it.

Thank you Colin2B.
Then if I have a very accurate clock in my pocket, no matter where I take it, I will not be able to tell if it is ticking faster or slower as I move from one energy density level to another, i.e., from a valley to a mountain top. It will simply tick away at its own "proper" time, and I will be none the wiser that synchronized clocks, when separated as they are moved to other environments, will not agree, until I compare them when they come back together.

The old adage holds true that a person with one watch always knows what time it is, but a person with two watches is never really sure .

[alancalverd]

Not quite. If you separate a pair of identical clocks, move one to a different gravitational potential, and exchange time signals between them, each sees the other as running at a different rate. No need to bring them back together.