According to current physics, is vacuum still something or nothing?

  • #1
Before that, Lawrence Kraus stated "Empty space is a boiling, bubbling brew of virtual particles that pop in and out of existence in a time scale so short that you can't even measure them" . After reading https://www.physicsforums.com/insights/physics-virtual-particles/ especially this statement "In particular, in a vacuum particles are nowhere created or destroyed, not even in the tiniest time interval", we can somehow conclude that vacuum is indeed nothing as creation out of nothing never happened and at the same time we can infer vacuum is neither created nor destroyed because it is simply nothing. But if space and particles are always there, what is there at the "time zero" or before Big Bang happened? Is there any particular conflict between this statement "In particular, in a vacuum particles are nowhere created or destroyed, not even in the tiniest time interval" and the whole Big Bang theory?
 

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  • #2
PeroK
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"Nothing" is not a particular helpful word in this context. The question is what is the (mathematical) model of the vacuum? In cosmology, the vacuum has a vacuum energy (dark energy) which appears in the Friedmann equation.

But, even the vacuum of Newtonian physics is time and empty space. It's a question then of whether you define space and time by themselves as "nothing". That's metaphysics, IMO.
 
  • #3
"Nothing" is not a particular helpful word in this context. The question is what is the (mathematical) model of the vacuum? In cosmology, the vacuum has a vacuum energy (dark energy) which appears in the Friedmann equation.

Interesting, assuming if the universe is not finite but unbounded but instead infinite, are dark energies everywhere?

But, even the vacuum of Newtonian physics is time and empty space. It's a question then of whether you define space and time by themselves as "nothing". That's metaphysics, IMO

Sorry, correct me if I'm wrong but isn't time relative that time is only possible only if there are existences such as gravity, electromagnetic rays, etc.?

Empty space with no time, everything, etc. will be absolute nothing. In fact, this is basically the absolute nothing that philosophers talked about. In reality, this will be of course impossible. So, we will understand that there is no such thing as nothing but only something. But is this scenario possible before the Big Bang event happened? But back to the previous statement "In particular, in a vacuum particles are nowhere created or destroyed, not even in the tiniest time interval", is there no conflict between this statement and the BB theory?
 
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Sorry, correct me if I'm wrong but isn't time relative that time is only possible only if there are existences such as gravity, electromagnetic rays, etc.?

Empty space with no time, everything, etc. will be absolute nothing. In fact, this is basically the absolute nothing that philosophers talked about. In reality, this will be of course impossible. So, we will understand that there is no such thing as nothing but only something. But is this scenario possible before the Big Bang event happened?
These are metaphysical arguments. You may define spacetime as "absolutely nothing". But, from a mathematical point of view, we can have different empty spacetimes: different numbers of dimensions, different underlying geometry etc.

But back to the previous statement "In particular, in a vacuum particles are nowhere created or destroyed, not even in the tiniest time interval", is there no conflict between this statement and the BB theory?
The BB theory doesn't say how our universe was "created", for want of a better word. It's a model of how our universe evolved from a very early time.

IMO, "before the BB" doesn't make sense until you specify the model you are using to extend the BB theory to include something "before".

IMO, these questions are so far beyond our everyday intuition that ultimately the mathematical model is all you have: or, at least, you have to lean very heavily on it. QM is already like that.

You may have missed my post the other day quoting Roger Bacon (1214-94):

Mathematics reveals every genuine truth, for it knows every hidden secret and bears the key to every subtlety. Whoever then has the effrontery to study physics while neglecting mathematics should know from the start that he will never make his entry through the portals of wisdom.
 
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  • #7
phinds
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... Lawrence Kraus stated
Kraus is a very entertaining pop-sci presenter and a great promoter of physics among the general public but should not be taken too seriously when you are reading his pop-sci books.
 
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  • #8
These are metaphysical arguments. You may define spacetime as "absolutely nothing". But, from a mathematical point of view, we can have different empty spacetimes: different numbers of dimensions, different underlying geometry etc.


The BB theory doesn't say how our universe was "created", for want of a better word. It's a model of how our universe evolved from a very early time.

IMO, "before the BB" doesn't make sense until you specify the model you are using to extend the BB theory to include something "before".

IMO, these questions are so far beyond our everyday intuition that ultimately the mathematical model is all you have: or, at least, you have to lean very heavily on it. QM is already like that.

You may have missed my post the other day quoting Roger Bacon (1214-94):

Mathematics reveals every genuine truth, for it knows every hidden secret and bears the key to every subtlety. Whoever then has the effrontery to study physics while neglecting mathematics should know from the start that he will never make his entry through the portals of wisdom.

Ok, I respect your opinions.

Kraus is a very entertaining pop-sci presenter and a great promoter of physics among the general public but should not be taken too seriously when you are reading his pop-sci books.

Agreed. That's why I immediately questioned his statement regarding universe coming out from nothing.
 
  • #9
phinds
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@wonderingchicken I have been puzzled by the tenor of your posts. I think @sophiecentaur hit the nail on the head when he said.
A lot of your recent posts suggest you would rather speculate about fringe stuff than get the basics straight.

You really would do well to learn some basic physics before you try to take on more complicated questions.
 
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  • #10
I have been puzzled by the tenor of your posts. I think @sophiecentaur hit the nail on the head when he said.
sophiecentaur said:
A lot of your recent posts suggest you would rather speculate about fringe stuff than get the basics straight.
You really would do well to learn some basic physics before you try to take on more complicated questions.

Are you saying I should learn by myself rather than asking questions here? No problem actually. There are many other places where I can learn physics.

Even asking a mere question makes some people overthinking, paranoid and take the negative side rather than the positive. 🤦‍♂️
 
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  • #11
phinds
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Are you saying I should learn by myself rather than asking questions here?
Absolutely not. This is a great place to ask questions. What I am saying is that you are asking questions that are beyond where your physics education gives you the wherewithall to fully understand the answers. I'm saying study the basics before jumping into complicated issues. A lot of the questions you are asking will be answered along the way.
 
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  • #12
sophiecentaur
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Even asking a mere question makes some people overthinking, paranoid and take the negative side rather than the positive.
There are two types of question. One is based on something that the questioner has clearly done some work on and the other type is just casting straws in the wind. Just take a look at a few random threads that have survived for a few pages of posts. They are usually based on well considered questions and they tend to get constructive answers.

You really shouldn't be surprised at the reception you've been getting. Read the statements about the purpose and rules of PF.
 
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  • #13
Absolutely not. This is a great place to ask questions. What I am saying is that you are asking questions that are beyond where your physics education gives you the wherewithall to fully understand the answers. I'm saying study the basics before jumping into complicated issues. A lot of the questions you are asking will be answered along the way.

There are two types of question. One is based on something that the questioner has clearly done some work on and the other type is just casting straws in the wind. Just take a look at a few random threads that have survived for a few pages of posts. They are usually based on well considered questions and they tend to get constructive answers.

You really shouldn't be surprised at the reception you've been getting. Read the statements about the purpose and rules of PF.

Then, this question remained unanswerable and thus can only be speculated with no definite answer?

So, so far, we are actually not sure whether vacuum with no gravity, time, electromagnetic fields, everything, etc. can be qualified as absolute nothing or something so we just leave it like that?
 
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  • #14
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So, so far, we are actually not sure whether vacuum with no gravity, time, electromagnetic fields, everything, etc. can be qualified as absolute nothing or something so we just leave it like that?
That kind of vacuum (no gravity, EM field, time e.t.c) can be qualified as absolute nothing imo, however in our universe, vacuum is not defined that way. In our universe vacuum contains at least gravity or EM field, because by definition that's how a point in our universe is defined, it is a point where gravity waves or EM waves have reach it at some time in the past.
 
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  • #15
That kind of vacuum (no gravity, EM field, time e.t.c) can be qualified as absolute nothing imo, however in our universe, vacuum is not defined that way. In our universe vacuum contains at least gravity or EM field, because by definition that's how a point in our universe is defined, it is a point where gravity waves or EM waves have reach it at some time in the past.
Yes, a vacuum with no time, gravity, everything, etc. is basically absolute nothing that the philosophers talked about but of course in reality, this is impossible. There are always gravity and EM fields everywhere so there is no such thing as absolute nothing in reality.

Which means, somehow in my opinion, Democritus got it a little bit, should I say, "right" when he said "Nothing exists except atoms and empty space; everything else is opinion." But instead of atoms, those are actually EM and gravity fields and various fundamental/elementary particles. So, somehow both nothing, regardless whether it is absolute or relative it doesn't matter, and something "depends" on each other.
 
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  • #16
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That kind of vacuum (no gravity, EM field, time e.t.c) can be qualified as absolute nothing imo, however in our universe, vacuum is not defined that way. In our universe vacuum contains at least gravity or EM field, because by definition that's how a point in our universe is defined, it is a point where gravity waves or EM waves have reach it at some time in the past.
Spacetime does not emerge from the current theories of EM or gravity. Spacetime is the underlying physical and mathemetical background, which must be presumed to "exist", in order for the theories of EM and GR to be stated.

QFT, likewise, starts with the assumption that there is an underlying spacetime on which the quantum fields may be defined.
 
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  • #17
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Spacetime does not emerge from the current theories of EM or gravity. Spacetime is the underlying physical and mathemetical background, which must be presumed to "exist", in order for the theories of EM and GR to be stated.

QFT, likewise, starts with the assumption that there is an underlying spacetime on which the quantum fields may be defined.
So you are trying to tell us that even that kind of vacuum is not absolute nothing but it is a portion of spacetime?
 
  • #18
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So you are trying to tell us that even that kind of vacuum is not absolute nothing but it is a portion of spacetime?
Define "absolute nothing". It's definitely part of spacetime. The Schwarzschild black hole, although it's not a model of our universe, is a vacuum solution to the EFE. It's mathematically distinguishable from flat Minkowski space, as it is curved. And, if you introduced a single test particle, you would see the physical difference.

To say that both are "absolute nothing" makes no mathematical or physical sense.
 
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  • #19
Define "absolute nothing". It's definitely part of spacetime. The Schwarzschild black hole, although it's not a model of our universe, is a vacuum solution to the EFE. It's mathematically distinguishable from flat Minkowski space, as it is curved. And, if you introduced a single test particle, you would see the physical difference.

To say that both are "absolute nothing" makes no mathematical or physical sense.

Absolute nothing, for the sake of discussion, is empty space which also known as vacuum or void without dimensions and geometries, time, gravity, EM fields, everything, etc.

What experiments out there that have validated the existence of Schwarzschild black hole and Minkowski space?
 
  • #20
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Absolute nothing, for the sake of discussion, is empty space which also known as vacuum or void without dimensions and geometries, time, gravity, EM fields, everything, etc.
If I say, for the sake of argument, that a plate with no food on it is "nothing", then is an empty plate nothing?

These are metaphysical questions and can lead nowhere - not on a science forum.
 
  • #21
If I say, for the sake of argument, that a plate with no food on it is "nothing", then is an empty plate nothing?

No. The plate itself isn't nothing. That's what people usually called as relative nothing. But if we started with the assumption/hypothesis that the universe is finite but unbounded, the "stuff" that serves as the background for the finite but unbounded universe is either nothing or something. From mathematical point of view, I'm not sure if the background is nothing or something. But if the background is infinite which means have no physical size/boundary, indivisible and devoid of any properties, the closest representation will be absolute nothing. But if the background is not nothing but something, that simply means the universe is infinite as a whole because usually people defined universe as everything that exist.

These are metaphysical questions and can lead nowhere - not on a science forum.

So, we arrived at a conclusion that there can be no single definite answer to the question because people defined things differently according to different contexts.
 
  • #22
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So, we arrived at a conclusion that there can be no single definite answer to the question because people defined things differently according to different contexts.
No, because "absolute nothing" isn't a thing in physics - it's not a well-defined term.
 
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  • #23
No, because "absolute nothing" isn't a thing in physics - it's not a well-defined term.
As vacuum without time, gravity, dimensions and geometries, energies, everything, etc., which is basically absolute nothing, is impossible in reality, I agreed there is no such thing in physics. But only remained as a hypothetical scenario.
 
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As vacuum without time, gravity, dimensions and geometries, energies, everything, etc., which is basically absolute nothing, is impossible in reality, I agreed there is no such thing in physics. But only remained as a hypothetical scenario.
It's the words that have no well defined meaning.
 
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  • #25
It's the words that have no well defined meaning.
I think your point is, for example, the phrase "there be (there is) nothing" is internally contradictory, excludes itself. The fact of asking this question is already something and supposing something. Therefore absolute nothingness is impossible.

Is that what you mean?
 

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