[Bill S (OP)]

Sorry; I couldn't resist the initial question.  It's really infinity I'm after, but discussions about nothing tend to be linked.

Infinity finds its way into many threads, causes a distraction, then fades away, usually, with no semblance of resolution.  Questions about infinity are often linked to questions about time and about nothing.

I propose asking a few questions, in the form of a poll, which may help to ameliorate the situation.  Each question requires only a yes/no answer, but hopefully these would be accompanied by some thoughts.   

1.  Is infinity a number?

2.  Is eternity a length of time?

3.  Is it possible to define Cantor’s “absolute infinity”?

4.  If there had ever been (absolutely) nothing, could there be something now?   

5.  Could there be change without time?

[alancalverd]

1. No

2. no

3. read Cantor

4. there obviously is something now, so the question is meaningless

5. there would certainly be no notion of time without change

[jeffreyH]

Alan's number 5 hits the nails on the head. Change never stops. We assume heat death will mean no change. What if there is no heat death of the universe? What if it is just not possible? I agree with Alan's 1 and 2. Cantor I have no knowledge of. I don't believe there was ever nothing.

[PmbPhy]

Q1.  Is infinity a number?

A1. No.

Q2.  Is eternity a length of time?

A2. No.

Q3. Is it possible to define Cantor’s “absolute infinity”?

A3. No.

Q4. If there had ever been (absolutely) nothing, could there be something now?   

A4. Yes

Q5. Could there be change without time?

A5. No.

[yor_on]

As for 3.

It's a very important question, and quantum mechanics defining a Planck scale seems very related to it, to me that is. Also the idea of many paths co-existing, as well as its opposite, the idea of a infinite, or at least undefined, amount of 'universes' branching at any observed outcome, only one apparent 'per observer'. They all go back to that question, and most interesting is the one about what happens under or close to that Planck scale.

5. change is 'time'', can't get one without the other. Causality is something added to that idea, giving us a commonly agreed on universe.

4. I don't know, wish I did. But, it depends on how you define it too, take 'Cantor's infinity' as a example. Or any of the other ideas above, what is the state of 'the instant' before a outcome? Does it belong to a arrow, or is it separated from it?

1. is meaningless, to me that is, and it's taken me some time to decide on that one. Alternatively, use any of the arguments above to define a 'infinity'.

2. Eternity? As ill defined as 'infinity' to me, doesn't tell me a thing. The 'instant in between' before that outcome, is that existing a 'eternity'?
=

don't get stuck on the arrows linearity for 2. Just assume opposites, a arrow, as contrasted to what is not a arrow. If you think of it from a arrow, then 'splitting eternity' from that, you just defined the arrow as the primary reason. That's not correct, both are as important and can be seen as a symmetry possibly, balancing out into a universe. Well, maybe

Or think of in terms of 'observer dependencies', giving both a equal 'local' importance. Then you will get both your 'infinity', as well as 'eternity' on one side, the arrow on the other. But they are meaningless to me anyway. I can't comprehend what they should mean from that side, only from 'inside' a universe.

[Bill S (OP)]

Thanks for the responses, hopefully there will be more to come.  As soon as I have a few spare minutes I will come back to the thread.

[dlorde]

4. There can't 'be' nothing, and it can't exist. 'Nothing' is an abstract concept of negation. Colloquial language makes it appear otherwise (e.g. "there's nothing in the box"), but generally refers to absence of certain types of stuff. A box that really had nothing inside wouldn't really be a box, because its sides would be touching each other.

To make a Hackenthorpe Vacuum: Take a bottle containing an ordinary vacuum, and suck all the vacuum out...

[yor_on]

As always, wish I was perfectly sober here. Dlorde, you just make a perfectly consistent defense for a container.

[Bill S (OP)]

3. read Cantor

Alan, I accept full responsibility for the unhelpful nature of this response.  My mistake was trying to make this question amenable to a yes/no answer.  As a non-mathematician I have struggled with much of Cantor’s work, but I think I have grasped the basics; particularly, I think I have a fair understanding of his thoughts on “absolute” infinity.  What I was really looking for was the thoughts of other posters about this. 

4. there obviously is something now, so the question is meaningless

“there obviously is something now,”  No question about that.
“so the question is meaningless”  I don’t accept that the question is meaningless.  Perhaps I need to rephrase it.
Given that there is something now, can there ever have been nothing?

There would seem to be three possible answers to this:  1. Yes   2. No and 3. Don’t know.  Any one of these would benefit from a bit embellishment.

5. there would certainly be no notion of time without change

I would not argue with that, but it’s a “sociologist’s” response: it’s an answer, but not to the question that was asked.
Could there be change without time?

[yor_on]

nope. no change no time. You measure it.
(and as always, locally)

[Bill S (OP)]

Alan's number 5 hits the nails on the head.

Jeffrey, I agree; shame it was not quite the right nail.  Can we go back to “Could there be change without time?”
I too have grave doubts about heat death.  I think it has to do with something Heisenberg said.

[Bill S (OP)]

A3. No.

Pete, I appreciate clear, concise answers like this, but I would be interested to know why you say “no”.

A4. Yes

How could that be?

[Bill S (OP)]

Yor_on, as so often happens with your posts, I read this one and thought: I’m sure he’s saying something significant here, I’m just not certain I know what it is.  I’m going to have to read it again and give it some thought.

[chiralSPO]

Regarding time and change:

We can think of a more generalized change as the partial derivative of some characteristic of the universe (or any system) with respect to some parameter. ∂something/∂time is one of the most common meaning of change, but we could chose many other parameters, such as position, temperature, pressure, composition etc. We could discuss the fundamentality of these parameters, but then again, how fundamental is time?

Can there be time without change? Sure, even if ∂something/∂time = 0, that doesn't mean that there is no time, it's just not relevant to that "something". For instance, think of all the parameters that are conserved in Newtonian physics and thermodynamics--as far as the total momentum of the universe is concerned, time is meaningless.

Causality gives time its directionality, and entropy is the proof.

[Bill S (OP)]

Dlorde; “Though shalt not with semantics round enmesh me……..”  With apologies to Omar Khayyam.
“There can't 'be' nothing, and it can't exist………… A box that really had nothing inside…..” No comment.

Go on! Answer the questions, in spite of yourself.   []

Seriously; I would value your answers.

BTW, I agree, in general, with your definition of nothing, and would like to say more about it, but at this point it would introduce thread drift, so I will come back to it later.  Prod me if I forget. 

[dlorde]

Go on! Answer the questions, in spite of yourself.   []

OK, here's my take:

Q1.  Is infinity a number?

A1. No.

Q2.  Is eternity a length of time?

A2. No.

Q3. Is it possible to define Cantor’s “absolute infinity”?

A3. Not as far as I know. He's supposed to have identified it with God, but I don't know how he defined 'God', and we can't ask him because he's dead. However, it's possible he did define God and left a record somewhere.

Q4. If there had ever been (absolutely) nothing, could there be something now?   

A4. Invalid/meaningless question. There can't 'be' nothing. Redefine 'nothing' as 'empty' (zero energy) spacetime for this question, and I'd say 'yes' (e.g., I'm told that the energy of matter & radiation, etc., is balanced by the 'negative' energy of gravity, resulting in an overall zero energy for our universe).

Q5. Could there be change without time?

A5. No. Change either requires or defines time.

[Bill S (OP)]

There can't 'be' nothing. Redefine 'nothing' as 'empty' (zero energy) spacetime

Perhaps I should reword the question:

If there had ever been a complete absence of anything, definable or otherwise by us, could there be anything now?

I would certainly not choose to redefine 'nothing' as 'empty' (zero energy) spacetime.  I suspect you would point out that spacetime is something.

[dlorde]

Perhaps I should reword the question:

If there had ever been a complete absence of anything, definable or otherwise by us, could there be anything now?

Same answer as before - it's a meaningless question. There can't 'be' a complete absence of anything - time itself is meaningless without spacetime.

[Bill S (OP)]

There can't 'be' a complete absence of anything

OK, Dlorde, over to you.  If absolutely everything ceased to exist, what term would you use to describe that.  This is a thought experiment, so don't point out either that that couldn't happen, or that if it did you wouldn't be around to describe it.

[dlorde]

If absolutely everything ceased to exist, what term would you use to describe that.

Meaningless. How would you describe it?

If an irresistible force meets an immovable object, what happens? Just a thought experiment, so don't point out that it couldn't happen  []