[phyti39]

There was nothing (a physical universe), then one came into existence. Since the elements (energy or matter) had no prior existence, they can't be used to bootstrap themselves into exixtence.

When you say the bolded above, do you mean there was a physical universe? because it seems to me a physical universe isn't nothing.

If you mean instead that there wasn't a physical universe (i.e. there wasn't anything at all, so no causes or reasons), then you seem to be contradicting yourself - if something cannot come into existence without a cause/reason (i.e. the elements (energy or matter)... can't be used to bootstrap themselves into existence), and there is something now, then it follows that there can't have been nothing (no cause or reason).

I'm puzzled...

Should have put "no" in place of "a". Nothing to me is literally "no thing", no matter, no energy, no physical laws. These things had to be introduced somehow. They do not bring themselves into existence. The "big bang" states the universe starts from a singularity, and even assigns an age. That just replaces one question with another.

[phyti39]

There was nothing (a physical universe), then one came into existence.

That's not known at this point. The Big Bang theory cannot be used to trace back to t = 0 but to only a short time after that. Therefore we cannot say what came before that time. There is a theory called the Pre-Big Bang theory which uses string theory to address some of those scenarios.

Since the elements (energy or matter) had no prior existence, they can't be used to bootstrap themselves into exixtence.

We don't know that either. There are particles which do "bootstrap themselves into existence". In fact many particles do that. There's a whole slew of them in particle physics which have been seen in the lab merely "popping into existence" from the inertial energy which is already there.

Quantum fluctuations, virtual particles, etc. result from energy and processes already in place. Prior to the "big bang" or whatever, that could not be the case, unless you propose a 'forever' universe.

[Ethos_]

Quantum fluctuations, virtual particles, etc. result from energy and processes already in place. Prior to the "big bang" or whatever, that could not be the case, unless you propose a 'forever' universe.

Frankly, that's exactly what I'd propose. I'll explain:

If our universe once sprang up within nothingness, as a few might suggest, it is quite likely it can happen again. The question is; How do we understand this nothingness from which our universe first came into existence?

There are those that will contend that nothing lies outside our present universe. In fact, they will suggest that there simply is no outside at all. If that's the case, and our universe is finite in both size and age, it came to being within an region that did not formerly exist. And that logic simply does not make any sense at all. If that region didn't exist, nothing could arise within it.

If the Big Bang is an accurate understanding of our universal evolution, we still can only go back to a very short time after this initial event. I therefore suggest that because space is here now, it has always been. And our local Big Bang is just that, a local event within an infinite cosmos of both size and age.

Nothingness is, IMHO an impossibility!

[Bill S (OP)]

Much earlier, I said:

“Dlorde; ……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.”

I tend to write my notes as though I were trying to explain points to someone else.  In this instance that was the case, so please excuse the style.  These are my thoughts on nothingness from a few years ago.

 I suggest a visualisation exercise.  For the sake of the exercise, we will assume the correctness of a number of theoretical positions: First, the Big Bang itself; secondly, that before the Big Bang, there was nothing and, thirdly, that inflation caused the infant universe to expand extremely quickly.  Now for the mental image: The Universe appears, out of nothing.  It inflates rapidly to the size of a beach ball.  Freeze the scene at this point and describe what you see in your mind’s eye.  Do not bother too much with the appearance of the Universe, it is the image of “nothingness” that is of interest.   

    All the people I have asked to undertake this exercise have described a sphere of light, surrounded by blackness which extends (some qualify this with such words as “presumably”) to infinity in every direction.  There is a second part to the exercise.  Now imagine two universes coming into existence simultaneously.  Freeze the action at the same point, and describe what you see.  The picture that emerges from those who have undertaken the exercise is of two spheres of light, separated by blackness, and surrounded by infinite blackness.  Two points need to be addressed here.  One is: does the second mental image really describe two objects with nothing between them?   The other must be: is this what nothing looks like?   

    If we talk of two runners, for example, finishing a race with nothing between them, we mean they are so close together that it is almost impossible to separate them.  Obviously, this is a figurative use of the term, because, unless they are actually in physical contact at all possible points, which is very unlikely, there will be at least a small amount of space between them.  Strictly, then, can we talk of two things having nothing between them if there is any sort of gap between them?  We might argue that there is nothing in that gap, but the gap itself must be space, and space, as relativity tells us, is something in its own right.  This must lead us to reason that if our two imagined universes have nothing between them, then they must be contiguous, with maximum surface contact.  This must prompt us to question the nature of the nothingness surrounding both the pair of universes, and the earlier single universe.  If we cannot have a space between them with nothing in it and justifiably call this “nothing”; how can we have space around our universe, or universes, and call that “nothing”?  This brings us to the second question: “is this what nothing looks like?”  The answer must be “no”, because nothing cannot look like anything.  Where does this leave us?  I believe it leaves us having to acknowledge that we cannot actually visualise nothing.  Many popular science books assure us (and rightly so) that we cannot visualise a fourth dimension of space, let alone the ten, or more, dimensions required by string theory, because we have no experience upon which to base such a visualisation.  In the same way, I suspect that our life experience prevents us from forming a mental picture of nothing, because we have never experienced it, either first hand, or through someone else’s description of it.  Our nearest experience is of “empty” space, so when we try to visualise nothingness, we use empty space, as a convenient substitute.  If space has ever been a suitable substitute image for nothingness, it certainly is not now, because, according to quantum theory it is far from empty.  Of course, there may be mystics somewhere who can visualise “nothing”.  Perhaps Fred Alan Wolf could find us a yogi who could do this.  The possibility must not be ruled out, but for the vast majority of us the fourth spatial dimension and “nothing”, together with the moment of creation of the Universe, will probably remain concepts we can acknowledge only intellectually, but never actually visualise.

As usual, I would appreciate comments/criticism.

[chiralSPO]

I think this thought experiment might be invalid because it requires the observer to be outside the beach ball universe(s). So you are already starting with a contradiction.

In the case of the two universes: I think this is an argument for considering more than just spatial dimensions. If there are multiple universes, and each is spatially all-encompassing, then they must either occupy the same space or have entirely different coordinate systems. By introducing even one additional dimension (one plus the three spatial and one temporal dimensions we are familiar with), these two universes can exist throughout all of 4D spacetime and still not have any overlap or contact.

[dlorde]

It seems to me a multiverse must consist of some meta-spacetime, particularly models that have universes 'continually' popping into existence and existing in 'parallel'. Whether this meta-fabric is a multidimensional view of the spacetime our universe is part of, or something different, it can't be nothing (because it spawns, or has spawned, universes).

If our universe is the only one and is finite, then it has no outside; it is all there is, and if you keep travelling 'straight' (a geodesic?) you never come to an edge, but may eventually revisit the vicinity of your starting point (if that is meaningful, given the time it would take and the ongoing expansion).

Just speculating...

[yor_on]

Multiverses are an abstraction, so are time without change. Both are important questions philosophically, to me at last. If you believe in the possibility of mutltiverses, do you also believe in the possibility of pure properties? That something to its nature can have a property that defines it?

I usually use linking 'c' to a clock, asking about that clock, ('c') split into Plank scale, one 'light step' at one 'Planck time', when I wonder about that one. Did that 'frozen instant' of one 'Planck step' also meant that we stopped its clock? (locally defined naturally, you can never get away from the observer and so such a experiment would be very hard to prove anything by, as the observers clock won't stop, and the observer defines the experiment.)

But let us assume that we by splitting 'c' into Planck scale also (locally defined) stop its 'clock'. Would you now define it as the property of that 'clock' still exist there?

Also, if we define a 'emergence' of something, to new properties that does not follow from what we know and can theorize about its constituents behavior before?
=

Also it becomes a question of the scale we use, if you think it's possible.

both questions are about properties, and if they are something more than just a idealization. If they are, what would that make a 'multiverse'?

[Bill S (OP)]

There are times when I wonder which is the more interesting when posting in these threads.  Is it the science, or the psychology?

The three responses so far all raise points that would be valid if my post were actually about multiple universes.  In fact, the post was about “nothing”; the single and double universes were introduced simply to illustrate different aspects of considering nothingness.

[yor_on]

It's the most exacting branching out of science Bill. We will build a whole wood here

[phyti39]

  All the people I have asked to undertake this exercise have described a sphere of light, surrounded by blackness which extends (some qualify this with such words as “presumably”) to infinity in every direction.  There is a second part to the exercise.  Now imagine two universes coming into existence simultaneously.  Freeze the action at the same point, and describe what you see.  The picture that emerges from those who have undertaken the exercise is of two spheres of light, separated by blackness, and surrounded by infinite blackness.  Two points need to be addressed here.  One is: does the second mental image really describe two objects with nothing between them?   The other must be: is this what nothing looks like?   
...
If space has ever been a suitable substitute image for nothingness, it certainly is not now, because, according to quantum theory it is far from empty.

You have identified the ambiguous words, "nothing" and "space".
If space has properties that are altered by the presence of mass as in gravity, and quantum fluctuations as in the casimer effect, then space, although invisible, has a form or structure. Nothing, being total absence of any thing, would have no properties. It would not have extent or measurement.
The figure of speech, "I see nothing" is more correctly "I do not see any thing".
A miniature universe embedded in a space would not be visible to an outside viewer.
With two, neither would be aware of the other. If the space of each merged then you would have one bigger universe.
The blackness has to be defined as "nothing" or "space".

My exercise would be to turn off photon production, and asking people what they imagine.

[PmbPhy]

You have identified the ambiguous words, "nothing" and "space".

Why do you say that they're ambiguous? To me they certainly aren't. They have very precise meanings even if space cannot be precisely defined. I.e. see http://users.wfu.edu/brehme/space.htm

Like time and matter-energy, it is not possible to define space in terms of simpler physical entities. Space simply exists. It can be defined only in terms of its properties. Those properties are what we call geometry.

The term nothing simply means the absence of matter, something that does not exist, the absence of all magnitude or quantity; also zero, nothingness or nonexistence.

If space has properties that are altered by the presence of mass as in gravity, and quantum fluctuations as in the casimer effect, then space, although invisible, has a form or structure.

Well stated.

Nothing, being total absence of any thing, would have no properties. It would not have extent or measurement.
The figure of speech, "I see nothing" is more correctly "I do not see any thing".

Seems okay to me.

A miniature universe embedded in a space would not be visible to an outside viewer.

I'm not quite clear what you mean by "miniature universe" since you're speaking of it in a way that is inconsistent with what our own universe is; our universe is not embedded in a space and can't even be though of as being so.

[phyti39]

You have identified the ambiguous words, "nothing" and "space".

Why do you say that they're ambiguous? To me they certainly aren't. They have very precise meanings even if space cannot be precisely defined. I.e. see http://users.wfu.edu/brehme/space.htm

Like time and matter-energy, it is not possible to define space in terms of simpler physical entities. Space simply exists. It can be defined only in terms of its properties. Those properties are what we call geometry.

The term nothing simply means the absence of matter, something that does not exist, the absence of all magnitude or quantity; also zero, nothingness or nonexistence.

If space has properties that are altered by the presence of mass as in gravity, and quantum fluctuations as in the casimer effect, then space, although invisible, has a form or structure.

Well stated.

Nothing, being total absence of any thing, would have no properties. It would not have extent or measurement.
The figure of speech, "I see nothing" is more correctly "I do not see any thing".

Seems okay to me.

A miniature universe embedded in a space would not be visible to an outside viewer.

I'm not quite clear what you mean by "miniature universe" since you're speaking of it in a way that is inconsistent with what our own universe is; our universe is not embedded in a space and can't even be though of as being so.

You know the necessity of good defintions, but Bill uses them with vague and uncertain meanings. The "miniature universe" is used as he presents it, being just as vague. The better his defintions, the less the participants can speculate!

[PmbPhy]

You know the necessity of good defintions, but Bill uses them with vague and uncertain meanings. The "miniature universe" is used as he presents it, being just as vague. The better his defintions, the less the participants can speculate!

I wasn't aware of that.

Bill. Is that true?

[Bill S (OP)]

For the sake of the exercise, we will assume the correctness of a number of theoretical positions: First, the Big Bang itself; secondly, that before the Big Bang, there was nothing and, thirdly, that inflation caused the infant universe to expand extremely quickly.

The reason I included these assumptions was to avoid speculation about where the “universe/s” might have come from; what their nature might be, or anything else about them.  The exercise was about “nothing”, and the perception of “nothing”.