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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: Yesterday at 14:27:55 »

Small enough to be mathematically treated as one for the task at hand.

I love math, I just don't want it to be confused with physics.

You can’t lie with math.  But it greatly aids obfuscation. 

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: Yesterday at 13:14:23 »

A point is not a "something". It is by definition infinitesimal, and therefore smaller than any "thing".

Infinitesimal is by definition: “an indefinitely small quantity; a value approaching zero.” My thinking is that if it is a quantity, and not zero, it must be something, but I am neither a mathematician or a physicist.

Experience teaches that trying to forge any kind of link between this sort of mathematical concept and the “real world” leads nowhere.  Possibly a “put-down” type answer like:

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

Where does it go from there?  Perhaps try saying what the “problem” is.  It’s always good to answer a question.

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?

No reply.  This is not an isolated example; which makes me wonder if I am asking a pointless question?

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 15/12/2018 23:09:37 »

Just like a millimeter is the gap between the jaws of a caliper gauge.

How small does something have to be to be a point rather than an object?

Are changes not events?

I really appreciate your taking a break from more pleasurable activities to answer possibly tedious questions.  Thanks.

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 15/12/2018 22:50:05 »

Distance is the separation of points, not objects.

I can see that it is the separation of points, but isn't it also the separation of objects, places etc?  E.g. is there not a distance between London and Cambridge?

Time is the separation of events.

Are changes not events?

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Science Experiments / Re: Finally created my Perpetual Motion Machine

« on: 15/12/2018 18:13:05 »

Eureka!  TNS presents perpetual motion!

Just follow the links from:

https://www.thenakedscientists.com/forum/index.php?topic=32581.0

No! Wait! That requires input from an idiot to click on the links.

Back to the drawing-board.

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 15/12/2018 15:50:16 »

Time and space are one thing.  Time lacks a preferred moment in the exact same way that space lacks a preferred location. 

I’ll have to ponder that a bit. My initial reaction is to wonder if it is just space that in influenced by relative motion, gravity etc. and that time – our measuring “instrument” – has to adjust to accommodate that change.

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 15/12/2018 15:41:33 »

If there were no calipers, that mm would have no meaning.
If there were no objects, distance would have no meaning.
If there were no change, time would have no meaning.

https://medium.com/the-physics-arxiv-blog/quantum-experiment-shows-how-time-emerges-from-entanglement-d5d3dc850933

Time is an emergent phenomenon that is a side effect of quantum entanglement, say physicists. And they have the first experimental results to prove it.

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 15/12/2018 13:14:47 »

Alan, that's a good one to keep in mind for next time the question of the possible quantization of time rears its head.
It doesn't address the question of where any fraction of a second could come from if there were no time.

My feeling is that when we talk about time/timelessness, what we are really talking about is change/changelessness. Time is what we call the measure of that change.  If there were no change, we would not be able to take measurements, so a measurement system would be extraneous. 

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 15/12/2018 12:56:52 »

The view is called eternal time, not tenseless time.

I tend to avoid the term "eternal time" because eternity and time are completely different concepts.  That's something which has probably been "flogged to death" elsewhere, without any resolution.   

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 14/12/2018 23:33:27 »

Yes, otherwise your body would not decompose.

Of course, it’s not as simple as that.  If I’m a solipsist, does my body decay when I die?

The answer to that must depend on several possible factors. They are all philosophical, so I’ll not list them. Suffice to say that I would opt for “no”.

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 14/12/2018 19:40:30 »

I don't buy the flow bit

That would seem to suggest “tensless” time, which I think equates, roughly, to John McTaggart’s “B series”. Have you read his “The Unreality of Time”?  It was a bit philosophical, not to mention pedantic, even for me. 

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 14/12/2018 19:30:23 »

That makes good sense to me.  My sticking point was that Phyti seemed to find a few milliseconds without time.

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 14/12/2018 18:41:55 »

How could the Universe have a frame rate if time didn’t exist?

The mind requires a few milliseconds to register sensory input, which can be the duration of your snapshot.

Where would the few milliseconds come from if time didn’t exist?

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 14/12/2018 18:11:57 »

Each physicist can see his own clock and the other’s with no time delay for information transfer.

If light speed is finite, there must be a time delay, which alters perception. Without a delay you can’t measure distance.

Of course, your comment is correct, but you seem to have overlooked the fact that this was a thought experiment.

….. which may not be the case.

Not the case

Could we be on the same page?

Time is not a causal factor. The time of an event is recorded after the event occurs, after awareness of the event. It's an historical account for a multitude of purposes.

Recall that I was trying to make sense of Barbour’s “Platonia”. 

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 13/12/2018 23:40:33 »

A few questionable lines.

Possibly some lines become more "questionable" when taken out of context.

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 13/12/2018 11:28:24 »

Areas of land are not points.

And analogies are not perfect representations of the things with which they are compared. I would rather not get into a discussion of the nature of points here.  I’m still waiting for clarifications elsewhere. I’m not going to suggest that continued waiting is “pointless”.

I know, this is somehow a discreet model where there is a concept of successive instants.  I find that contradictory, but that's me.

It’s certainly not just you, but it’s another of those subjects that seem to be interminable.

How can a snapshot be observed at any other time than the time of the snapshot?

I think the main thrust of Barbour’s reasoning was that there is no “time of the snapshot”.  The illusion of time is added by the observer.  I had (have) trouble with this because if there is no time before the observation is made, how can it be made?

That is well put.  I agree with that more than you know.

Thanks. This is probably not the place for it, but I would love to hear more about your ideas on that. Possibly another thread.  What would be the best question to ask to evoke an appropriate response?

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 12/12/2018 23:11:07 »

Unfortunately the adoption of digital information processing has led to many similar misconceptions, including the redefinition of a circle as 360 straight lines

I think Edwin Abbot beat them to that "definition" of a circle.

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 12/12/2018 23:06:05 »

Two events separated by space but not time are termed 'simultaneous', not 'contiguous'.

Precisely. Remember that I was trying to grasp Barbour’s idea of “Platonia” as illustrated by the “snapshot” concept. I was trying to get away from the semantics to see if that would help. It didn’t.

That would be the same point then.

Not necessarily. Two areas of land are said to be contiguous if they share a common boundary.  Two of Barbour’s snapshots would be contiguous if their borders were together, but none of this sheds any light on the “mechanism” by which a timeless array of snapshots can become sequential without time in which to make that change.

  I don't see how there could be a 'snapshot' without there being a time to which the snapshot corresponds.

Exactly.  I felt there must also be a specific time in which each snapshot was observed. I couldn’t equate that with the timelessness of “Platonia”.

I have photos taken of me, but all of them were taken at some moment in time.

I suspect the analogy was not intended to be taken that far. 

The usual term is 'mind', which is is not the 'brain',

Barbour’s term, not mine.

If time doesn't exist, then there would be no meaning to my age, or the velocity of this here rock.  Of course time exists.

It’s some years since I read “The End of Time”, but that was roughly the point I was at when I reached the end; with the proviso: Of course time exists, in our Universe.

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 12/12/2018 19:59:00 »

This is not possible.

That was my initial reaction.  I’ve explained, above, why I didn’t leave it at that.

If a rock were to roll in a series of discrete jumps you would need to apply an infinite force for an infinitesimal time, first forward and then backward, to make it do so.

I tried a few simpler “thought experiments”, but they all raised the same question as yours.  How could they work in a timeless Universe? 

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 12/12/2018 19:47:34 »

As points, you can discuss such geometric relations as their separation and such.

Separation in space is a related, but rather different, issue. It was “separation” in time I was trying to understand.

Not sure what contiguous events are.  Points are not usually described as being contiguous.

I interpreted “contiguous” as having nothing by which they are separated.  We were talking earlier about the events of birth and death.  Obviously, these are not contiguous, in normal circumstances. Using the “snapshot” idea I was trying to imagine a situation in which it would be possible to have “snapshots” that didn’t exist in time, but could be “interpreted” sequentially by the brain; using “unreal” time.  It didn’t make sense to me, but Barbour is a professional and I an ill-informed amateur, so I was trying to follow his reasoning.

OK, so you're talking about quanta of time, sort of like frames of a movie.  Somehow I suspect our brains don't process reality at the frame rate of the universe, if there is any such thing.

Another of my stumbling blocks.  How could the Universe have a frame rate if time didn’t exist?