[Bill S (OP)]

Time and Classical and Quantum Mechanics: Indeterminacy vs. Discontinuity   Peter Lynds

https://arxiv.org/ftp/physics/papers/0310/0310055.pdf

I’ve had this on my external HD for well over a decade, and have decided to read it, or delete it.  Available time being what it is, I’ll have to take it in bits; so please have patience.

On the subject of a static interval of time, Lynds says:

Regardless of how small and accurate the value is made however, it cannot indicate a precise static instant in time at which a value would theoretically be precisely determined, because there is not a precise static instant in time underlying a dynamical physical process. If there were, all physical continuity, including motion and variation in all physical magnitudes would not be possible, as they would be frozen static at that precise instant, remaining that way. Subsequently, at no time is the relative position of a body in relative motion or a physical magnitude precisely determined, whether during a measured time interval, however small, or at a precise static instant in time, as at no time is it not constantly changing and undetermined.

In QM, a quantum is precise and indivisible, but processes that follow the rules of QM progress via a succession of quanta.  Could it be reasoned that time progresses via a succession of individually static instants?

Lynds thinks not.  He says:

We begin by considering the simple and innocuous postulate: ‘there is not a precise static instant in time underlying a dynamical physical process.’ If there were, the relative position of a body in relative motion or a specific physical magnitude, although precisely determined at such a precise static instant, would also by way of logical necessity be frozen static at that precise static instant. Furthermore, events and all physical magnitudes would remain frozen static, as such a precise static instant in time would remain frozen static at the same precise static instant. (Incidentally, the same outcome would also result if such a precise static instant were hypothetically followed by a continuous sequence of further precise static instants in time, as by their very nature a precise static instant in time does not have duration over interval in time, so neither could a further succession of them. This scenario is not plausible however in the first instance, as the notion of a continuous progression of precise static instants in time is obviously not possible for the same reason).

How logical is the reasoning, here?  Consider this:  “a precise static instant in time does not have duration over interval in time,”

What this seems to say is that an instant in time has no duration.  Theoretically, one might argue that something can exist for a period of no time; but on a practical level, that makes no sense.  Surely, if something has no temporal duration, it does not exist in time, and since it is time we are considering, that makes little sense.

[alancalverd]

Semantics.

A point on a line has no length. A point on a timeline has no duration. What's the problem?

[yor_on]

Well. according to Einstein time is a local definition, is it not?
So, from where would one then define those 'instants'?

Take your choice

[Bill S (OP)]

A point on a line has no length. A point on a timeline has no duration. What's the problem?

I have no problem with either of those, in principle.  However, in practice, can you show me a point that has no length, but is still there?

Similarly, a point on a timeline that is defined as having no duration may be theoretically valuable, but both the timeline, and the point are mathematical tools.  What would be a physical example?

[Bill S (OP)]

So, from where would one then define those 'instants'?

That's one of the things I hope to glean from the article.  My own feeling is that it would have to be one's own RF.  That leaves the questions:
If the "instants" are different in different RFs, how can they all be of zero duration? 
If they are all of the same duration, how do they differ from one another?
If they don't differ, what does that say about the local definition of time?

[yor_on]

That's a pretty good question Bill.
Pick a choice

A "absolute 'galactic' frame"
Or no 'absolute frame'?

If there is none, how would you go about defining those instants?
Is there a way to make them 'fit' a 'whole universe' in some objective sense, instead of local definitions?

[yor_on]

The point is actually important to me
It's Alice in wonderland

You turn it around and then?
Because logic tells me that all 'instants' are the same, just as 'c' is
Well, my logic then :)

A instant becomes a clock when repeated, as defined locally
==

If you think of it, a lot of our definitions are expected to be 'objective' although they are made as local measurements/experiments. We define repeatable experiments as those that you can repeat under similar circumstances, anywhere and at any time. It doesn't state anything about what the 'universe' should be seen as, just that the experiments done should be repeatable.

[Bill S (OP)]

A instant becomes a clock when repeated, as defined locally

I'm OK with that, but, is Lynds?

  (Incidentally, the same outcome would also result if such a precise static instant were hypothetically followed by a continuous sequence of further precise static instants in time, as by their very nature a precise static instant in time does not have duration over interval in time, so neither could a further succession of them.

[yor_on]

Well, I'm as always of two minds :) What one can note is there is some prerequisite you have to accept to discuss it. It goes out from a notion of a whole universe in where those 'instants' either may exist, or not. That's not the 'instants' Relativity speaks of, as they must be observer dependent. So whose 'instants' should we take as a given? It's a fundamental to me, this first question. Presuming that there is a isotropic homogeneous universe, and from that also presume that what holds at one place and time will hold at another, you come down to a principle in where 'instants' should be of a same duration, if they exist. It's the idea of a 'flow' relative 'quanta of time' that's discussed as far as I get it, right?

[Bill S (OP)]

Well, I'm as always of two minds

I envy people who have two!  I have only one, and I think that's wearing out. 

Getting busy here, but I hope to think about your comments while doing other things.

[Bill S (OP)]

As I said above, I think the only “instants” we can consider are those in own RFs; but in terms of the reasoning of Lynds, this still leaves the questions in #4 unanswered.

I think the presumption that we inhabit an isotropic homogeneous universe is essential to much cosmological thinking, and that the presumption that what holds at one place and time will hold at another, follows from that. 

Does that mean that Lynds should have been more specific about the provenance of his instants?

[Bill S (OP)]

It is not necessary for time to “emerge” and “congeal” out of the “quantum foam” and highly contorted space-time geometry’s present preceding Planck scale (Gh/c 3 ) 1/2 just after the big bang (new inflationary model), as has often previously been tentatively hypothesized.  Continuity would be present and naturally inherent in practically all initial quantum states and configurations, rather than a specific few, or special one, regardless of how microscopic the scale.

What would it mean, for time to “emerge” and “congeal”?

Emergence is change, change requires time, so time would have to precede the emergence of time; which makes no sense.

What is “uncongealed” time?   Could it be time without direction? 

How could that be identified as time?

[yor_on]

I think of 'emergence' in one way more Bill. To me it means something new, as in not expected. And the question there is whether this is true? Either there exist 'jumps/emergence' or it's just us not finding the right way to follow the chain leading to a 'emergence'.

There I wonder :)

[Bill S (OP)]

So, can you have "emergence" that does not involve change?

[yor_on]

No

Not as I think about it anyway, if you remember a common example of a emergence is water becoming ice, having new and unexpected properties. But the question there would be if that is due to our lack of understanding. I don't know, in some way it connects to whether time is a 'flow' or 'instants', to me at least. It's the same principal question of how things work with a 'flow' then representing a more Newtonian universe in where cause and effect is traceable. And where 'instants' then would be 'jumps'

[Bill S (OP)]

Obviously, “emergence” has various shades of meaning, so if by the emergence of time, we mean that time becomes visible after being concealed, or comes to prominence, after fulfilling only a minor role; then it is quite justifiable to talk of time emerging.  However, talking of time emerging in a scenario in which there was previously no time, is a cat of a different colour.

[jeffreyH]

Things happen. We call these events. We can compare one event with another. One may be a projectile and the other the readout on a clock. Ultimately, we are comparing one change against another.

[yor_on]

Alan made a good point I suspect. We use mathematics as the tool describing the universe, but the mathematics often use dimensionless 'points' in quantum logic, well, as it seems to me. Although each of us see and measure a possibly infinite universe having dimensions we can 'move' inside, that doesn't really tell us what someone 'outside' this universe would see looking at 'it'.

the way around it using quantum logic is then to think of it as 'waves' in a 'field', If you do that the 'field' becomes our universe, and another question should become, is such a field 'contained' in some manner?  If it is, what 'contain it'. As a slightly outrageous notion, presume that what we call 'dimensions' from an inside all are 'illusions', and that the logic creating the tangible universe we see might be 'time' :)

But that's not enough, you also need cause and effect

[Bill S (OP)]

Things happen. We call these events. We can compare one event with another. One may be a projectile and the other the readout on a clock. Ultimately, we are comparing one change against another.

While this is, undoubtedly true, it doesn't address the question whether/how something might "emerge" if time were not available to facilitate the change.

Nor does it address the question of something emerging from nothing.

[Bill S (OP)]

Alan made a good point I suspect. We use mathematics as the tool describing the universe, but the mathematics often use dimensionless 'points' in quantum logic, well, as it seems to me.

   
As I have said before, I acknowledge the use of these tools in maths, and respect those with facility in their use.  However, I’m not holding my breath while waiting for someone to demonstrate a physical example of a dimensionless point. 

Although each of us see and measure a possibly infinite universe having dimensions we can 'move' inside, that doesn't really tell us what someone 'outside' this universe would see looking at 'it'.

I assume you are not using “universe” meaning everything that exists.

As a slightly outrageous notion, presume that what we call 'dimensions' from an inside all are 'illusions',

I would say there’s nothing outrageous about that, as long as you acknowledge that the “illusions” are part of the reality of our Universe.

…and that the logic creating the tangible universe we see might be 'time'

Only if you regard time as an entity independent of anything else.

But that's not enough, you also need cause and effect

Why?