The Nature of Time

[Lorentz Jr]

1 minute ago, swansont said:

There’s a reason why we use “t=0” rather than “now”

What's the reason? At the point in time when I set a clock to zero, t=0 corresponds to "now".

1 minute ago, swansont said:

You appear to have a fundamental misunderstanding of the rules of speculations

Please enlighten me, swanson. So far, your comments have been just as vague as iNow's.

[Lorentz Jr]

1 minute ago, iNow said:

Which is just moving the goalposts. 

Ah, "moving the goalposts". I've seen that expression on this forum before. Never with any explanation of what the goalposts are or how they've been moved, only as little one-line "zingers", as though quoting that catch phrase somehow proves anything.  🙄

[iNow]

3 minutes ago, Lorentz Jr said:

Ah, "moving the goalposts". I've seen that expression on this forum before. Never with any explanation of what the goalposts are or how they've been moved, only as little one-line "zingers", as though quoting that catch phrase somehow proves anything. 

I can explain it for you, but I can’t understand it for you (that was a zinger!)

https://rationalwiki.org/wiki/Moving_the_goalposts

[Lorentz Jr]

38 minutes ago, iNow said:

“Now” you’re just making stuff up. 

Well, I don't want to get into another flame war with another senior poster by pointing out that "Now you’re just making stuff up" is a perfect example of "not a single word of supporting logic or evidence", or the fact that a phrase means something doesn't imply that someone isn't using it for empty rhetorical purposes, so ... thanks for chatting, guys. Have a nice day.

Edited January 9, 2023 by Lorentz Jr

[Markus Hanke]

11 hours ago, mistermack said:

Yes, but if you do that, you are assuming a clock

You are also assuming a ruler when you draw out your 3D coordinate system. 

12 hours ago, mistermack said:

and that clock is essentially no difference to the system you are modelling

Yes, it is different - that’s what I’ve been attempting to demonstrate in that graphic I provided earlier. A clock provides an additional degree of freedom that uniquely specifies the evolution of the system. It’s extraneous information that removes the ambiguity inherent in a 3D-only graph of your system. Mathematically speaking, a time axis is orthogonal to each of the three space axes, so time “information” is linearly independent from the spatial hypersurface. 

You do not seriously propose that we can just do away with time in all our physics models and expect it to still work out correctly, do you? Surely you can see that this doesn’t work.

12 hours ago, mistermack said:

a physical change in 3 dimensions

If all the available dimensions are spatial in nature, and there is no other external information, how will there be “change”? 

[geordief]

7 hours ago, iNow said:

see. Please tell me where exactly in our universe we can measure “now.

I can't suggest how to measure it but my  idea is that the "nows"(or "thens) are everywhere  with one to each fleeting frame of reference.

I don't think we can just say that "now does not exist"(even if for a sentient entity that "now" is incredibly  composite and inferred).

 

All the "nows" have to be related and no one "now"  is any different from another "now" as far as I can see.

 

They are only "now" in their own frame of reference  and their duration (what could be measured) is perhaps non existent  except insofar as their relationships with neighbouring "nows"  can be quantified.

 

Yes GPS  does stand out (ie the conceptual breakthrough of the space'time continuum) but I do wonder if there nay have been other conceptual breakthroughs in the past

 

What,I wonder might have been the first perception that gave rise to the concept of time for example?

Or is a  concept   of time just hardwired  into existence including sentient existence?

[studiot]

10 hours ago, iNow said:

Please elaborate. 

As far as light is concerned, how long does it take for light to travel from A to B ?

 

7 hours ago, Lorentz Jr said:

What's the reason? At the point in time when I set a clock to zero, t=0 corresponds to "now".

No necessarily.

Think hard about this before you respond reactively.

This occurs because there is no absolute time.

[geordief]

7 minutes ago, studiot said:

 

This occurs because there is no absolute time.

Does "absolute" mean the opposite of "defined relatively" in this context?

The same (or closely related) idea as that there is no preferred frame of reference in relativity?

[studiot]

Just now, geordief said:

Does "absolute" mean the opposite of "defined relatively" in this context?

The same (or closely related) idea as that there is no preferred frame of reference in relativity?

I mean quite simply that I can set the watch on my wrist to zero any 'point in time' I want.

But GMT will not be zero at that point, even though my watch is 'in' the frame of GMT.

 

When you have more than one frame the t = 0 and t' = 0 may not coincide.

We usually consider the case of them coinciding to make calculations easy.

[Genady]

1 hour ago, geordief said:

What,I wonder might have been the first perception that gave rise to the concept of time for example?

The first such perception might be a perception that something has changed.

[geordief]

13 minutes ago, studiot said:

But GMT will not be zero at that point, even though my watch is 'in' the frame of GMT

If "GMT" is refined to represent just one event  at one location and time in Greenwich,and that event is non-composite(something perhaps like the decay of a single particle or -if such exists-a single quantum fluctuation)  could it be said that ,in its own  frame of reference only that a point called zero could be identified(but not measured)?

18 minutes ago, Genady said:

The first such perception might be a perception that something has changed

Maybe it would have to be a sequence of changes,not just a binary one.(connecting the dots )

[Genady]

8 minutes ago, geordief said:

Maybe it would have to be a sequence of changes,not just a binary one.(connecting the dots )

Maybe, but why. Any one-step change seems to have all that's needed for giving rise of concept of time.

[geordief]

10 minutes ago, Genady said:

Maybe, but why. Any one-step change seems to have all that's needed for giving rise of concept of time.

The one-step change would have to have its context.

Maybe that would provide a concept of quantifiable time whereas the one-step  change would be less significant.(in practice I can't see any sentient being being aware of a one-step change without a context in the background)

 

I wonder what would be the most primitive creatures with a body clock or equivalent. 

Does ,for example a virus measure time in any sense?

[Genady]

41 minutes ago, geordief said:

The one-step change would have to have its context.

Maybe that would provide a concept of quantifiable time whereas the one-step  change would be less significant

I don't think that the very first concept of time needs to be a quantifiable time. That could come later.

'Something' in the 'change of something' is the context.

45 minutes ago, geordief said:

I wonder what would be the most primitive creatures with a body clock or equivalent. 

I can't connect a body clock with the concept of time. The concept rises with a perception of change.

[geordief]

7 minutes ago, Genady said:

 

I can't connect a body clock with the concept of time. The concept rises with a perception of change.

The human body clock has to perceive  changes  in brightness,doesn't it?

It must have sensors  in the body to facilitate the perception.(the eyes,I expect)

 

And the first living creatures  developed sensors  too I may have heard.

[Genady]

3 minutes ago, geordief said:

body clock has to perceive  changes

to sense, not to perceive

[geordief]

3 minutes ago, Genady said:

to sense, not to perceive

It has to process the input from the sensors.

 

Is that different to perceiving?

[Genady]

5 minutes ago, geordief said:

It has to process the input from the sensors.

 

Is that different to perceiving?

Yes, it is:

Quote

As verbs the difference between perceive and sense

 is that perceive is to see, to be aware of, to understand while sense is to use biological senses: to either smell, watch, taste, hear or feel.

(Perceive vs Sense - What's the difference? | WikiDiff)

[swansont]

12 hours ago, Lorentz Jr said:

What's the reason? At the point in time when I set a clock to zero, t=0 corresponds to "now".

 “now” is not well-defined for anyone else, unlike t=0. 

 

12 hours ago, Lorentz Jr said:

Please enlighten me, swanson. So far, your comments have been just as vague as iNow's.

Speculations does not mean anything goes. While one may introduce a speculation (if they follow the rules of the speculation section), responses need to be established science . We are limited to following relativity.

[iNow]

4 hours ago, studiot said:

As far as light is concerned, how long does it take for light to travel from A to B ?

You responded to my request for elaboration with a question. That's a bit rude, TBH. Your question strikes me as irrelevant to the point I made, but I surely am missing something.

Will you please elaborate further (about your actual point, not with some Socratic method of questioning) to help us close this gap in our mutual understanding?

[studiot]

1 hour ago, iNow said:

You responded to my request for elaboration with a question. That's a bit rude, TBH. Your question strikes me as irrelevant to the point I made, but I surely am missing something.

Will you please elaborate further (about your actual point, not with some Socratic method of questioning) to help us close this gap in our mutual understanding?

My apologies if you have truly not heard of this before.

https://www.wtamu.edu/~cbaird/sq/2014/11/03/why-is-time-frozen-from-lights-perspective/

[swansont]

3 minutes ago, studiot said:

My apologies if you have truly not heard of this before.

https://www.wtamu.edu/~cbaird/sq/2014/11/03/why-is-time-frozen-from-lights-perspective/

“Time is not frozen from light's perspective, because light does not have a perspective.”

So one can’t provide an answer to “As far as light is concerned, how long does it take for light to travel from A to B ?”

[studiot]

Or one can say zero time ?

[Mordred]

1 hour ago, studiot said:

Or one can say zero time ?

That just leads to a whole range of misconceptions. It's better and more accurate to simply point out that anything moving at c isn't an inertial frame of reference. Hence follows a null geodesic.

[swansont]

2 hours ago, studiot said:

Or one can say zero time ?

That implies there is an equation with a solution that is zero. But there is no equation.