Author Topic: what is the definition of the universe?  (Read 7717 times)

Udayana

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Re: what is the definition of the universe?
« Reply #25 on: May 18, 2022, 12:06:16 PM »
...

You started this thread on the "definition of the universe" - confirming the existence or not of whatever you end up defining is a separate activity.
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Udayana

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Re: what is the definition of the universe?
« Reply #26 on: May 18, 2022, 12:07:54 PM »
You mean like the Multiverse?

What multiverse?
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ProfessorDavey

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Re: what is the definition of the universe?
« Reply #27 on: May 18, 2022, 01:18:58 PM »
... Genesis starts with the creation ''In the beginning'' not ''before the beginning''
But as the writers of genesis will have considered both before and beginning as time-related terms then ''before the beginning'' would make no sense as the beginning is a term that means "has no before".

But this is again linked to a simplistic view of time as somehow a constant and only going in one direction.

Walt Zingmatilder

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Re: what is the definition of the universe?
« Reply #28 on: May 18, 2022, 01:41:11 PM »
But as the writers of genesis will have considered both before and beginning as time-related terms then ''before the beginning'' would make no sense as the beginning is a term that means "has no before".

But this is again linked to a simplistic view of time as somehow a constant and only going in one direction.
Not really, since there is no attempt at stating anything happens before.

I think the real issue is defining the universe as infinitely old and yet wanting the luxury of there effectively being no such thing as ''old'' because time doesn't go in one direction.

Is time not constant for the observer measuring time? Is time not constant on clocks?

ProfessorDavey

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Re: what is the definition of the universe?
« Reply #29 on: May 18, 2022, 01:51:58 PM »
Not really, since there is no attempt at stating anything happens before.
My point exactly - the writers of the bible, not unreasonably given their complete lack of understanding of the universe, don't address what happened before the beginning. Of course they don't as their mindset would consider "before the beginning" to be oxymoronic.

Yet, however, they completely fail to address where this god of theirs came from.

ProfessorDavey

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Re: what is the definition of the universe?
« Reply #30 on: May 18, 2022, 01:57:04 PM »
I think the real issue is defining the universe as infinitely old and yet wanting the luxury of there effectively being no such thing as ''old'' because time doesn't go in one direction.
You really do struggle with this concept, don't you Vlad - so wrapped up in simplistic and traditional human-centric thinking.

Try this one - image a completely circular running track. Where is the beginning?, where is the end of that track? Is it infinite given that you could theoretically keep running around it forever and never come to the end. If there are two runners, which one is in front and which is behind.

Is time not constant for the observer measuring time?
No

Is time not constant on clocks?
No

Walt Zingmatilder

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Re: what is the definition of the universe?
« Reply #31 on: May 18, 2022, 02:00:05 PM »
My point exactly - the writers of the bible, not unreasonably given their complete lack of understanding of the universe, don't address what happened before the beginning. Of course they don't as their mindset would consider "before the beginning" to be oxymoronic.

Yet, however, they completely fail to address where this god of theirs came from.
We can discuss that on the christian thread.

At the moment though the role of time in describing the universe is not settled among physicists with many verging on saying that time is irrelevent.

I don't feel in a position to define time, do you?

Walt Zingmatilder

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Re: what is the definition of the universe?
« Reply #32 on: May 18, 2022, 02:05:55 PM »
You really do struggle with this concept, don't you Vlad - so wrapped up in simplistic and traditional human-centric thinking.

Try this one - image a completely circular running track. Where is the beginning?, where is the end of that track? Is it infinite given that you could theoretically keep running around it forever and never come to the end. If there are two runners, which one is in front and which is behind.
So is this your description of the universe ?
We know, for instance that they are not running backwards. Their direction is always forwards.

ProfessorDavey

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Re: what is the definition of the universe?
« Reply #33 on: May 18, 2022, 03:23:14 PM »
I don't feel in a position to define time, do you?
No - but it is you who describe matters relating to time in a manner that seems to presume that time is uni-directional and constant. In implying those assumptions then you do seem to be defining what time is. I don't presume such definitional matters.

ProfessorDavey

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Re: what is the definition of the universe?
« Reply #34 on: May 18, 2022, 03:27:31 PM »
So is this your description of the universe ?
No - merely an analogy to explain how things can be rather more complicated than they first appear.

We know, for instance that they are not running backwards. Their direction is always forwards.
No we don't - in my analogy let's now assume that we have two objects moving around that circular track. How do you know whether they are moving forwards or backwards - you don't except by providing your own assumptions on directionality, which may be wrong. And whether one appears to be moving forwards or backwards is completely defined by the perspective of the observer. 

jeremyp

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Re: what is the definition of the universe?
« Reply #35 on: May 18, 2022, 03:53:42 PM »
And yet I recall you once suggested that the universe ''Just is''.
No, I suggested it was at least as likely as "God just is" which is your position. At least we have evidence that the universe exists.

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Walt Zingmatilder

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Re: what is the definition of the universe?
« Reply #36 on: May 18, 2022, 04:36:33 PM »
No - merely an analogy to explain how things can be rather more complicated than they first appear.
And that, it seems is as far as it goes
Quote
No we don't - in my analogy let's now assume that we have two objects moving around that circular track. How do you know whether they are moving forwards or backwards - you don't except by providing your own assumptions on directionality, which may be wrong. And whether one appears to be moving forwards or backwards is completely defined by the perspective of the observer.
And what evidence do you have that this is how the universe is constituted as a circle. Who do you suppose can observe the universe in the way you suggest.
Surely the scientific measure of directionality in the universe is entropy.

Walt Zingmatilder

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Re: what is the definition of the universe?
« Reply #37 on: May 18, 2022, 04:46:46 PM »
No, I suggested it was at least as likely as "God just is" which is your position. At least we have evidence that the universe exists.
No ''God just is'' is not my position and God satisfies the criteria for sufficient reason for the universe which is the opposite of the universe just is. A definition of the universe would have to surely include what it is about the universe that makes it necessary and necessary for it's own existence. And that's why we have to get to grips with what the universe is. The universe existing doesn't actually answer these questions and is just another form of ''The universe just is''.

Dicky Underpants

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Re: what is the definition of the universe?
« Reply #38 on: May 18, 2022, 06:42:41 PM »

Surely the scientific measure of directionality in the universe is entropy.

Well, life has been ignoring the 2nd Law of thermodynamics for millions of years - presumably because the earth is an open system, taking in energy all the time. I'm no physicist or biologist, but we have no evidence that Life is going to stop its 'progress' in gaining complexity (unless Mr Putin and his cronies put an end to it). If this is the case, entropy should eventually be reversed as life takes over the whole universe. Will the entropy of the rest of the universe win out in trillions upon trillions of years?

Some of the speculations of physicists and cosmologists strike me as utterly futile, except as thought experiments which could never be verified. I once heard Patrick Moore on Parkinson's show suggest that in the infinity of the universe, a little green man in a studio billions of miles away might well be simultaneously having an interview on a talk show like the one he was on.
I would have thought the concept of 'simultaneity' (since Einstein) had no meaning whatsoever over such vast distances, so this was an absurd suggestion.
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Le Bon David

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Re: what is the definition of the universe?
« Reply #39 on: May 18, 2022, 07:33:44 PM »
Hmmmm You've never struck me as a ''potential things'' sort of guy. These are things which, I take it there is no evidence for. That seems like a departure for you.

The multiverse, really? Can that be demonstrated? Is that scientific?
The multiverse may not exist.  This local presentation may be all there is. We dont know.
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ProfessorDavey

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Re: what is the definition of the universe?
« Reply #40 on: May 19, 2022, 09:23:15 AM »
No ''God just is'' is not my position and God satisfies the criteria for sufficient reason for the universe which is the opposite of the universe just is.
But Vlad, you continually fail to define god in a sufficiently robust manner to come close to determining whether that definition satisfies the criteria for sufficient reason. So how on earth you can conclude it satisfies those criteria is quite beyond me.

But also a judgement that something exists because it has to exist (not that this has come close to being demonstrated for god) is pretty well an argument that that thing "just is" - so you do seem to be terribly confused.

And we've discussed this concept, and its corollary of necessary entity, perviously. The notion that something could have sufficient reason and/or be a necessary entity doesn't mean it does have those features. All sorts of things could be claimed to be of that nature - the argument only gains traction when there are no other explanations that do not require that entity to exist that are credible, or further that all other explanations have been demonstrated to be false. So in the context of the universe we need to ask the question - are there credible explanations for the universe that do not require god and the answer is, of course there are - many of them, plenty of which are imbued with the levels of evidence that is completely lacking for god.

But we can go further - this seems to be based on the premise that somehow there must be a necessary entity or sufficient reason, in other words that the universe could not, theoretically, not exist. That claim seems to lack credence - just because the universe actually exists doesn't mean that theoretically it must exist. I used a child/parents analogy previously and will state it again. If I exist then my parents must have existed (they are necessary entities) - but that does not mean that my parents theoretically could not have existed - of course they could, and it would mean that I wouldn't exist either.

Dicky Underpants

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Re: what is the definition of the universe?
« Reply #41 on: May 19, 2022, 09:47:41 AM »
Could an expert on entropy step forward please?
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ProfessorDavey

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Re: what is the definition of the universe?
« Reply #42 on: May 19, 2022, 09:52:17 AM »
And what evidence do you have that this is how the universe is constituted as a circle.
I'm not proposing evidence for curvature of the universe - that isn't the point of my analogy. The point is to demonstrate that it is easy to get beyond the simplistic notion of unidirectional and constancy and into the world of infinity (in the context of no beginning or end) and further to demonstrate that the notion of forwards and backwards are often observer based biases.

But of course there is credible theoretical evidence that the universe is constituted in this manner:

https://en.wikipedia.org/wiki/Shape_of_the_universe

Who do you suppose can observe the universe in the way you suggest.
Err physicists - as indicated in the article.

Udayana

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Re: what is the definition of the universe?
« Reply #43 on: May 19, 2022, 01:05:24 PM »
Could an expert on entropy step forward please?

Not an expert, but willing to look at any questions.
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Nearly Sane

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Re: what is the definition of the universe?
« Reply #44 on: May 19, 2022, 01:31:23 PM »
Could an expert on entropy step forward please?
I used to be an expert on entropy but I am completely uncertain now.

Dicky Underpants

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Re: what is the definition of the universe?
« Reply #45 on: May 19, 2022, 01:59:20 PM »
Not an expert, but willing to look at any questions.
Well, perhaps you could amplify something on the matter I raised. Life, it appears, is ignoring entropy, presumably because the earth is in an 'open system' and continually drawing in energy. However, I presume life cannot ignore the 2nd law of thermodynamics forever, and eventually life must end along with the universe? I realise this may be a very simplistic way of looking at things, and with deference to the Prof, seems like a nod to viewing time as linear.
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Dicky Underpants

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Re: what is the definition of the universe?
« Reply #46 on: May 19, 2022, 02:00:54 PM »
I used to be an expert on entropy but I am completely uncertain now.
The old clockwork running down, eh?
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Le Bon David

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Re: what is the definition of the universe?
« Reply #47 on: May 19, 2022, 02:29:18 PM »
The old clockwork running down, eh?
Tick to....

Udayana

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Re: what is the definition of the universe?
« Reply #48 on: May 19, 2022, 02:53:03 PM »
Well, perhaps you could amplify something on the matter I raised. Life, it appears, is ignoring entropy, presumably because the earth is in an 'open system' and continually drawing in energy. However, I presume life cannot ignore the 2nd law of thermodynamics forever, and eventually life must end along with the universe? I realise this may be a very simplistic way of looking at things, and with deference to the Prof, seems like a nod to viewing time as linear.

Yes, you're correct. Life, on earth, exists in an open system - one where energy and matter can enter and leave. As life is "self-organising" it becomes more ordered, so may appear to ignore the 2nd law, but of-course as it functions - ie. consuming, excreting, moving, thinking and so on, it participates in an increase, overall, of entropy in the system as a whole - and in the eventual (hypothetical) "heat death" of the universe.

Though this fits in well with our perception of time "flowing" only forwards, we can't actually derive that from considering the 2nd law and entropy. 
 
« Last Edit: May 19, 2022, 02:58:54 PM by Udayana »
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ProfessorDavey

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Re: what is the definition of the universe?
« Reply #49 on: May 19, 2022, 03:08:45 PM »
Yes, you're correct. Life, on earth, exists in an open system - one where energy and matter can enter and leave. As life is "self-organising" it becomes more ordered, so may appear to ignore the 2nd law, but of-course as it functions - ie. consuming, excreting, moving, thinking and so on, it participates in an increase, overall, of entropy in the system as a whole - and in the eventual (hypothetical) "heat death" of the universe.

Though this fits in well with our perception of time "flowing" only forwards, we can't actually derive that from considering the 2nd law and entropy.
Some stuff on this here:

https://en.wikipedia.org/wiki/Entropy_as_an_arrow_of_time#Cosmology

So I guess a fundamental question would be whether time is really directional, or appears to be due to its relationship with entropy. But also what would happen to time were we to reach complete steady state equilibrium whereby entropy no longer increases - would time stop.

Interesting conjecture on whether time would reverse if the universe stopped expanding and started to contract.