Why is there something instead of nothing?

[Melthadora]

I had this thought which bugs me:

"If absolutely nothing existed, reality wouldn't exist either. Therefore, absolute nothingness cannot be real. And thus, something has to exist."

Thoughts? Can it stand as a logical statement?

Why do you think there might be something instead of nothing?

Edited August 30, 2020 by Melthadora

[joigus]

Hi. Welcome. Very old question, but very difficult to answer nonetheless. So I'm going to get hold of some visual aids found on the web.

Nothingness is quite easy to picture in your mind. Maybe we get that picture from our hours of sleeping without dreams. I don't know. But,

The picture of the closest thing to nothingness that we can build from physics is not a featureless scenario. It's more like this:

Or, more diagramatically, like this:

A perpetual struggle of opposites annihilating each other. It just isn't just nothing. What it suggests is that what we call "nothing" is more like this ephemeral tug of war between ephemeral somethingnesses (virtual particle-antiparticle pairs). Nothing (in a poetic picture derived from serious physics) is a struggle between opposites in which nobody wins. At some point in the past, somebody won (why that was so is still an enigma; I don't like the word "mystery".)

The status of the theory so far is that something like this sea of opposites annihilating each other must have fell downhill some kind of modulating field (inflaton field) 13 point something billion years ago, generating real particles and filling the universe with structure. That's called inflationary model of the universe.

I hope that helps, but it's been a long time since Leibniz set that question to nowadays. So the story has become more involved.

[Eise]

2 hours ago, Melthadora said:

"If absolutely nothing existed, reality wouldn't exist either. Therefore, absolute nothingness cannot be real. And thus, something has to exist."

I am not a physicist, but in A Universe from Nothing, Lawrence Krauss says that "Nothingness" is unstable. The "Nothingness" that joigus talks about is the 'emptiest' we can reach in our universe. Nothingness in our universe is a bit like a water surface: it can be in complete rest when simply looking at it, but zooming in, you will see molecules bouncing in each other, some of them escaping the surface, some others (or the same) caught at the surface.

So a "Nothingness" still less then absolute vacuum in our universe would be unstable, and could produce the Big Bang. However, somehow the laws of nature should somehow exist, i.e there must be a road from absolute nothingness to our universe.

[Melthadora]

Woah, Joigus! Thank you for the info. The visual aid looks amazing, too. How can I look up the math behind it? I'd love to dive into some hard science, and not only play around with logic and philosophy (I hope that my level is enough to understand the equations!) 

So, judging from the above, nothingness is a system of somethings that keep cancelling each other out. So, even if it's nothingness for all technical purposes, it still isn't absolute absence of everything. So, the question still stands: Why?

I asked philosopherai.com - it's a great ai you can ask about anything. It suggested that, if absolutely nothing existed, the concept of reality wouldn't exist either, and so my statement is false (yep, the ai is that good!). But if the nature of reality itself goes beyond mere concepts, the ai's answer is the one that doesn't stand. I wonder which of both is it.

3 hours ago, joigus said:

The status of the theory so far is that something like this sea of opposites annihilating each other must have fell downhill some kind of modulating field (inflaton field) 13 point something billion years ago, generating real particles and filling the universe with structure.

Are there any theories about why that sea fell downhill?

And now I wonder about why entropy exists in the first place. And why it's expanding. Maybe the universe is filled with small nothings that keep exploding. (I'm getting random here, I know).

1 hour ago, Eise said:

I am not a physicist, but in A Universe from Nothing, Lawrence Krauss says that "Nothingness" is unstable. The "Nothingness" that joigus talks about is the 'emptiest' we can reach in our universe. Nothingness in our universe is a bit like a water surface: it can be in complete rest when simply looking at it, but zooming in, you will see molecules bouncing in each other, some of them escaping the surface, some others (or the same) caught at the surface.

So a "Nothingness" still less then absolute vacuum in our universe would be unstable, and could produce the Big Bang. However, somehow the laws of nature should somehow exist, i.e there must be a road from absolute nothingness to our universe.

This is an interesting addition to joigus' post. I like your simile about the water. 

You could say that what I actually wonder about is how the laws of universe came into existence, indeed.

I need to look up that book. Thanks!

Edited August 30, 2020 by Melthadora

[joigus]

12 minutes ago, Melthadora said:

So, the question still stands: Why?

Good question, but very difficult to answer. Part of the key to that could be related to the observation that Eise has introduced and you so cleverly have caught on to:

31 minutes ago, Eise said:

However, somehow the laws of nature should somehow exist, i.e there must be a road from absolute nothingness to our universe.

This sets the stage for the famous question of meta-laws: Were the laws of physics already there before the big bang, or did they appear along with everything else? Answering that or setting the question properly (if we can ever do it) will probably get us closer to trying to answer your question. So far, what we've got is this kind of parametrisation of the problem (the inflationary model).

One should also ask what "there" and "then" or "before" really mean, as space-time is supposed to have appeared along with matter. The misleading aspect of the picture that I linked to before is that it seems to suggest an extended background (especially in time). It should be conceived of as something of Planckian dimensions (very, very small). And what about time? I don't know. There are several things about inflation I can't quite wrap my head around. To me, overall, it all looks a little bit contrived to be entirely satisfactory. Another major concern of modern theoretical physics is the emergence of time. The potential energy "down which the vacuum fell" does not live in space-time, but in the inflaton-field configuration space. But physicists that work on inflationary models do use a pre-big-bang time as a background for it. Somehow, you must be able to define a sequence of events.

19 minutes ago, Melthadora said:

Are there any theories about why that sea fell downhill?

Sorry, my word "sea" was not very fortunate. It would be better described as a Planckian-small bundle of fields, I suppose.

Well, there are models, all under the name of "inflationary model" something or other; not to explain, but at least to model what must have happened. Basically you put quantum field theory (this theory of particle-antiparticle formation and annihilation) on the background of a field of potential energy. If you set the curve correctly*, you can model much of what must have happened to give rise to the universe as we know it. Inflationary models seem to be particularly good at explaining the seeds of inhomogeneity that gave rise to clusters and superclusters that today are galaxies and clusters and superclusters of galaxies.

I must warn you that some very no-nonsense physicists are not completely happy about inflationary ideas. One notable example is Neil Turok.

The best source for learning about these things that I know of is Leonard Susskind's online lectures (Stanford). There's also Lawrence Krauss, that Eise suggested.

------------------------------------

In answer to:

1 hour ago, Melthadora said:

I'd love to dive into some hard science, and not only play around with logic and philosophy (I hope that my level is enough to understand the equations!) 

It depends a little bit on how familiar you are with differential calculus, vectors, power series, things like that.

There are many confusing aspects, I know. I'm leaving many questions unanswered. I'm not sure I've done a good job of making it more understandable.

*"Model the curve correctly" means it must look something like this (take a look at the graph):

At the bottom down of the curve is where the big bang is supposed to have started. "Previous" to that, there is a very prolonged phase of "slow roll", as it's called.

[MigL]

For simple to understand and easy to read sources, you can't beat the original.
The Inflationary Universe, Alan Guth, 1997

[joigus]

Yes, that's true. The theory has changed since then, but not substantially, and the original motivations are probably introduced better by the original author.

[studiot]

20 hours ago, Melthadora said:

I had this thought which bugs me:

"If absolutely nothing existed, reality wouldn't exist either. Therefore, absolute nothingness cannot be real. And thus, something has to exist."

Thoughts? Can it stand as a logical statement?

Why do you think there might be something instead of nothing?

One way to approach a difficult problems is to break it down into small steps ie substitute a series of lesser questions in this case.

So we have

How many ways can something exist ?   I suggest a great many.

How many ways can nothing exist ?   I suggest at most one.

So the substutute question becomes

Statistically why are we suprised that something exists ?

[Eise]

18 hours ago, Melthadora said:

So, judging from the above, nothingness is a system of somethings that keep cancelling each other out. So, even if it's nothingness for all technical purposes, it still isn't absolute absence of everything. So, the question still stands: Why?

Because of the uncertainty principle. One of its forms says that in a process energy and time cannot be defined precisely together. But from that follows that an absolute vacuum cannot exist, because you would now the exact energy: 0. So for short times particles can pop into existence, and pop out again. This is what you see in joigus' animation. We know these processes are real, because otherwise we cannot explain the exact spectroscopic lines we see; and then there is the vacuum pressure that can be measured in the Casimir Effect.

18 hours ago, Melthadora said:

You could say that what I actually wonder about is how the laws of universe came into existence, indeed.

Then you are not alone. The laws of nature are useful abstractions, i.e. abstract descriptions, of natural processes. The only thing we can say about nature is that obviously there are regularities, otherwise the formulation of any law of nature would be impossible. But how to apply the idea of regularity when we talk about a one-time event, like the big bang? How can we derive, from a situation of nothingness, that there are (will be?) regularities, and even stronger, that they can be described by our present laws of nature?

 

Edited August 31, 2020 by Eise

[studiot]

1 hour ago, Eise said:

Because of the uncertainty principle. One of its forms says that in a process energy and time cannot be defined precisely together. But from that follows that an absolute vacuum cannot exist, because you would now the exact energy: 0. So for short times particles can pop into existence, and pop out again. This is what you see in joigus' animation. We know these processes are real, because otherwise we cannot explain the exact spectroscopic lines we see; and then there is the vacuum pressure that can be measured in the Casimir Effect.

This is a good explanation of the animation. And also of our universe as we know it. Sure.

But not, in my opinion, a good example to quote in relation to a deeper question such as this one that ranges more widely.

Energy, for instance, in not a 'thing' at all, but a fictional concept, convenient to our paricular presentation of Physics.

Time and its nature is an even more inscrutible concept that has seen many lengthy discussion threads since the inception of SF and way back before.

We should examine the questions,

In order for something to exist does it need somewhere for it to exist and somewhen for it to exist?

Relativity has shown that this condition is not necessary - we have also discussed this at great length here.

 

[Eise]

56 minutes ago, studiot said:

This is a good explanation of the animation. And also of our universe as we know it. Sure.

And it was only meant as that: a simple description of the quantum vacuum in our universe. Nothing more.

1 hour ago, studiot said:

Energy, for instance, in not a 'thing' at all, but a fictional concept, convenient to our paricular presentation of Physics.

That's why I said 'particles pop into and out of existence'. 

[studiot]

Another complication for the OP to consider is

What do you mean by  'is'  ?

Can something 'exist' whether we have discovered it or not ?

It is possible (in fact that is the way we construct them today) to construct the entire number system from nothing.

That is repeated copies of the empty or null set.

 

[joigus]

I wish to clarify first that the animation is not mine.  

Also correct my grammatical mistakes:

23 hours ago, joigus said:

must have fell fallen downhill

The first occurrence that I know of in the history of physics that something like the concept of changing physical laws appeared in physics was due to Dirac. He made the observation that different ratios of the most natural physical parameters in the universe (number of protons, size of cosmic horizons, number of photons, leptons, fundamental constants, like Newton-Cavendish' famous G, etc.) were very simple powers of a number the order of 10⁴⁰. So Dirac thought something like "maybe all these constants are not really constants, but are related to the age of the universe by some simple power law and they are changing with cosmic time". Then the idea fell out of favour and something like that kind of reasoning has seen a re-birth, mainly possibly spurred by Alan Guth and followers.

The question of meta-laws (using words I've heard to Lee Smolin) I think is a very interesting one. It is not inconceivable that Planck's constant may have been nearly zero at the starting point, or G_Newton had assumed a much bigger value in the past, etc. Who knows. Guth's inflationary idea, when you think about it, is a kind of revival of something very similar in a perhaps more tractable version. In that case it's the vacuum in quantum field theory that plays the role of changing parameter, monitoring most everything else, in particular the Hubble expansion parameter. My feeling is that Guth has captured something quite right about how it all must have started to give rise to the big bang of which we're seeing the remnants in the sky. In particular, quantum fluctuations must have played a very important role, being essential to the seeding of inhomogeneities that gave rise to cluster, supercluster, and galaxy formation. So I generally agree with what Eise has explained about uncertainty and I think it complements very well the points I have let loose. It's the uncertainty principle in combination with the choice of a convenient vacuum that gave rise to the structure. Until a better idea is found, it seems to work pretty well.

The problem of the "when", that Studiot has brought up, is something that worries me particularly (the "where" worries me a little bit less), because you always seem to need a parameter to deploy all the physics as a sequence of events. When we're assuming Planckian scales in the spacial sections of space time, does it really make sense to talk about eternal inflation or slow roll? That's why the question of emerging time is so important. The only way I can think of that something like this could be achieved is by deriving time from a metric in field space, which is what I tried to suggest in the thread "What is time?" @Markus Hanke didn't seem to agree with me or see very clearly what I meant. And I tend to take Markus' disagreement very seriously. But that's another story and belongs in other thread.

-------

PD.:

I kind of have an idea of what this timeless scenario (from which a time can be derived that could make mathematical sense) may be derived from, but it's embryonic and very mathematical, and this is probably not the right medium for it.

I will also have to pass on the fine philosophical/mathematical points that Studiot suggests, for the time being (and important though they may be) as I don't feel qualified to talk about them. The idea of constructing something from nothing still boggles my mind. I'll try and think more about it. I suppose everything depends on what is nothing and what is something.

[studiot]

Another point to take into consideration is the difference between the virtual particles suggested and real (material) particles is the with virtual particles the end result is always zero ie the always sum to zero, depending upon  properties under consideration.

[joigus]

1 hour ago, studiot said:

Another point to take into consideration is the difference between the virtual particles suggested and real (material) particles is the with virtual particles the end result is always zero ie the always sum to zero, depending upon  properties under consideration.

Good point. The best explanation I can think of comes from classical relativistic mechanics, and it foreshadows the need for a quantum field theory, including "messenger particles" and vacuum polarization.

1) Classically, you cannot have a massive particle emit a photon

2) Classically, you cannot have a pair of particles appear from the vacuum

Proof:

1) Particle at rest goes to particle + photon

From conservation of momentum:

\[\left(m,0,0,0\right)=\left(E,p,0,0\right)+\left(p,-p,0,0\right)\]

\[m=E+p\]

From Einstein's energy-momentum relation:

\[\Rightarrow E^{2}-p^{2}=E^{2}+p^{2}+2Ep\Rightarrow\]

So that,

\[p^{2}=-Ep\Rightarrow\]

So either,

\[p=0\] (the particle does not decay)

or else,

\[p=-E\]

Impossible, as we've assumed p>0

2) Particle-antiparticle pairs (from the vacuum)

\[\left(0,0,0,0\right)=\left(E,p,0,0\right)+\left(E,-p,0,0\right)\]

\[2E=0\]

So E is zero, which is again impossible.

---------------

There are more examples, but they all go to prove that particles that are produced at one point and annihilated at another are a mathematical impossibility from the classical POV. In the case of the massive particle sending a photon out, you need another charged particle coming nearby and absorbing that photon so that the uncertainty principle allows the intermediate particle go unnoticed. The closer both charged particles are, the more efficient this exchanging mechanism is, so that the force must decrease with the distance. If you think about it, it makes sense that it be an inverse square law. In the case of vacuum polarization, it is required that the pair disappears soon enough that the UP allows you to, again, get away with it (UP).

These particles that appear at one point and disappear at another are what in quantum field theory corresponds to so-called "internal legs" of the Feynman diagrams. You can and must use them, they appear in the space-time picture as intermediate steps in the evolution of the overall quantum states, but they are ephemeral presences, doomed to be turned back into the vacuum or absorbed by real particles sooner rather than later.

Edited August 31, 2020 by joigus
minor addition

[studiot]

8 minutes ago, joigus said:

but they are ephemeral presences, doomed to be turned back into the vacuum or absorbed by real particles sooner rather than later.

And, of course, if there are real particles to do the absorbing there is not 'nothing', by definition.

[joigus]

Yes, you're right. But I do have lots of problems with the concept of nothing, because whenever I try to think about it, it's from some kind of somethingness.  

Following the current cosmological models, this quantum vacuum had to go through the slope of the inflaton field, and it had to have cooled before re-heating for billions upon billions of "years" (e⁵⁰ plus e-foldings) so...

Is the inflaton nothing? And the quantum vacuum?

I don't know. I wouldn't even know how to get started trying to answer that kind of question. None of that seems like nothing to me. It's so similar to something that only someone who's an real expert about the something/nothing characterisation would be able to tell the difference.  

[joigus]

1 hour ago, joigus said:

e⁵⁰ plus e-foldings)

Sorry, 50 e-foldings, not e⁵⁰, meaning the universe multiplied its size by e (=2.718...) 50 times (at least).

https://arxiv.org/pdf/1405.5538.pdf

Edited August 31, 2020 by joigus

[MigL]

I think we had better first define a common meaning of "nothing'.

One example has already suggested by joigus, Studiot and Eise.
Classically, an absence of particles could be considered 'nothing', as a field is just a value at each point in space.
But quantization tells us that that field will have excitations which are virtual if less than a quantum of action, and real if more.
IOW, with QM, a field is more than just values at different points, but gives rise to virtual or real particles; and is definitely not 'nothing'.

Now, I like the idea that there is no background stage ( absolute frame ? ) on which events unfold, and lean towards the concepts espoused by GR and LQG; there is no 'background stage', it is all fields on fields ( even space-time is a geometric field ).
So the concept of 'absolute nothingness' becomes meaningless once QM is accounted for, as it can never exist.

[joigus]

Ok, but suppose that the naive idea of this "nothing" approached by mentally picturing the removal of things that happen to be there into nonexistence does not ultimately make sense. It's not about getting hold of these things (a planet here, a giant star there) and taking them somewhere else; it's more like snapping your fingers and decreeing that they never were. That's not an operation that you can do, or even think of doing.

I think you guys know me by now. I'm very mathematically minded. I always try to write the equations we know to work and have them tell me something, suggest something to me. Not because I think I'm good at maths, but because I trust the equation more than my words or concepts. At some time in the past I read a book by George Gamow that quoted Dirac as saying "the equation knows best". I think that's one of the most brilliant thoughts in physics that's ever been formulated. Whenever you find conflict, you must stick to the equation and try to make sense of it.

Right now, what the equations seem to suggest is that there is no simple formulation of "nothing". So, "what's the next best thing?", my question would go.

And the most plausible next thing is either the remote-past "nothing" (quantum vacuum confined to a Planckian-size bubble, rolling down a hill, with no real particles) or huge extensions of interstellar space, devoid of matter, in the remote future, if the picture of the accelerated expansion of the universe is correct. Right there you've got two different pictures of "nothing". How can that be?

So my conclusion would be: I'm puzzled by the fact that we can so easily conceive this nothingness (or we think we can: close your eyes and think of nothing), and yet the universe doesn't let us even get closer to it, or make sense of it. Different versions of nothingness or incremental approaches to it just doesn't add up in my mind.

I also like the idea of ridding ourselves of the background. I'm sorry I'm not all that familiar with LQG. Although some of the ideas are attractive to me. It's the discretization of ST that I don't like.

[joigus]

On 8/30/2020 at 12:57 PM, Melthadora said:

"If absolutely nothing existed, reality wouldn't exist either. Therefore, absolute nothingness cannot be real. And thus, something has to exist."

I suppose I agree with this, in some way, and I also think it goes deep. +1

My phrasing of it would be, "there's always something."

[MigL]

2 hours ago, joigus said:

I'm sorry I'm not all that familiar with LQG. Although some of the ideas are attractive to me. It's the discretization of ST that I don't like.

You might not like it, but if you are comfortable with GR, and consider space-time geometry, the 'field', which we call the gravitational field, then, quantizing gravity implies quantizing that field to get a quantum field theory.
IOW, quantizing the space-time geometry by making it discrete.

What did you think would be quantized in a quantum field theory of gravity ?

[joigus]

42 minutes ago, MigL said:

You might not like it, but if you are comfortable with GR, and consider space-time geometry, the 'field', which we call the gravitational field, then, quantizing gravity implies quantizing that field to get a quantum field theory.
IOW, quantizing the space-time geometry by making it discrete.

What did you think would be quantized in a quantum field theory of gravity ?

I no longer think a quantum theory of gravity is likely to happen. Not the canonical way, and not with Feynman diagrams and renormalization the traditional way. Maybe a more topological language for QFT/gravitation has to be developed. I do believe that the holographic principle partially grasps something very surprising about gravitation. My own intuition guided by comments, lectures, reflections and papers of other physicists is that something very fundamentally different happens at Planck's scales that must be interpreted in some new way, maybe that the interior of a very small region of space-time no longer makes sense. Or maybe the distinction interior/exterior becomes fuzzy at that scale...

But I'm old enough and battered by experience enough to accept whatever proves to be a better solution. If it just so happened that discreteness for space-time works better, so be it. I hope it's within my lifetime.

Edited August 31, 2020 by joigus

[StringJunky]

2 hours ago, joigus said:

I suppose I agree with this, in some way, and I also think it goes deep. +1

My phrasing of it would be, "there's always something."

Would it be feasible to say that the pre-BB the universe was in a sub-quantum state and therefore not measurable, so essentially, nothing measurable existed then. What I'm suggesting is that sub-quantum is the nearest thing to nothing that can exist because virtual particles only exist briefly in combination.

[joigus]

24 minutes ago, StringJunky said:

Would it be feasible to say that the pre-BB the universe was in a sub-quantum state and therefore not measurable, so essentially, nothing measurable existed then. What I'm suggesting is that sub-quantum is the nearest thing to nothing that can exist because virtual particles only exist briefly in combination.

This is actually, IMO, an outstanding question, because I haven't the faintest idea how you would apply the principles of the quantum theory of measurement to the vacuum. I don't suppose you can do that. Certainly, as there were no real particles, only those ephemeral virtual states, how did something actually happen? Nothing would qualify as an observer or as an apparatus.

Decoherence is not it, IMO, because I don't know of any instance in which the vacuum can be argued to bring about decoherence and thereby qualifying as producing a measurement. This is a part of the quantum theory of measurement that's slipped into oblivion: the problem of the pointer positions. What physical tag says that something, and not something else, has actually happened? What tips the arrow?

If anybody knows of any answer to that I would be the first to thank them, because I've longed to know for more than 20 years. It was very frequently referred to in the old papers and books about measurement, but no longer is.

Old papers and books:

https://press.princeton.edu/books/hardcover/9780691641027/quantum-theory-and-measurement

Edited August 31, 2020 by joigus
addition