Are you sure....I mean absolutly, one hundred percent sure, that empty space is not a myth

[Mitch Bass]

I'm asking members of this society this question although its been almost a year since I last was active...i assure you...what i was getting at has been streamlined and revamped...I am goibg to stop this because i realize i am not following protocol so...

[Strange]

What do you mean by "empty space"?

 

In reality, there is no perfect vacuum and so space is never truly empty. And at the quantum level, there are always particles appearing and disappearing. Space is always full of fields, such as the electromagnetic field or the Higgs field.

[ydoaPs]

I'm asking members of this society this question although its been almost a year since I last was active...i assure you...what i was getting at has been streamlined and revamped...I am goibg to stop this because i realize i am not following protocol so...

Do you mean spacetime sans any matter or do you mean a true vacuum in a universe containing matter? Either way, the answer is: neither are real.

[John Cuthber]

I know enough about quantum mechanics to know that, at the exact moment you asked that question, I was in possibly in empty space (by any sensible definition).

Feel free to disprove this assertion.

[Theoretical]

Space itself is something.

https://en.m.wikipedia.org/wiki/Metric_expansion_of_space

"Distances increase as more spacetime fills in between galaxies"

[Strange]

Space itself is something.

https://en.m.wikipedia.org/wiki/Metric_expansion_of_space

"Distances increase as more spacetime fills in between galaxies"

 

That is just a metaphor (and a rather poor one). If you follow the "spacetime" link in that sentence, it says that spacetime is a mathematical model (not a "thing").

[Theoretical]

That is just a metaphor (and a rather poor one). If you follow the "spacetime" link in that sentence, it says that spacetime is a mathematical model (not a "thing").

The Wikipedia article gives the OP models and metaphors.

 

This topic is extensive. Another area is frame dragging,

https://en.m.wikipedia.org/wiki/Frame-dragging

[TheGeckomancer]

I'm asking members of this society this question although its been almost a year since I last was active...i assure you...what i was getting at has been streamlined and revamped...I am goibg to stop this because i realize i am not following protocol so...

 

There is no way to be SURE of this without scanning every inch of the universe.

[ydoaPs]

There is no way to be SURE of this without scanning every inch of the universe.

Why?

[hoola]

it seems logical that the universe may have once consisted of a true void, not even space. Space, and all that goes along with it may be the current state of a mathematical structure held in place with a durable sub-logic that evolved from prior states. IOW, time must have preceded space as space needed "time" to evolve...although it is interesting to think that from the first tick of time, the observed structures were rather inevitable in their form....how many universes can a void spit out? It seems it could spit out trillions, but how many have a "durable substructure"; what we call logic? Following that thinking, there could be a short shelf life on all but a few, maybe just one...I see once again it's amusing to think that some of the gamma ray bursters that have no detectable source are nascent universes in deep space that disintegrate due to in part, to these unstable (short-lived) sub-logics, but can "deliver the goods" long enough to have a measurable effect in our universe, as the thing fizzles out. I would imagine a larger component of the odd GRBs are from identical logic structures to ours, but our existing universe interferes with them in gestation from physical proximity, allowing for a selective pressure in the void environment for only one universe at "time" to be extant...pretty lucky for us if true. So it seems that the odd GRBs could have two main types..

Edited December 5, 2015 by hoola

[KipIngram]

I'm going to go out on a limb here - this is a notion that just occurred to me in the past few days, but it has a "right feel" to it. I don't think spacetime really exists as an entity unto itself. What you have is "stuff." Lots of words for that; events, objects, particles, fields, etc. Things that do, in some way, have their own reality. Spacetime is a framework that we've invented that lets us organize our perception of the "stuff" in a useful, sensible way. Without the "stuff" there's nothing to organize and no need to invent the framework.

 

So spacetime arises from the relationships among events. So asking if "empty space" exists anywhere is really asking if there are places in our framework with no "stuff" associated. I don't really know the answer to that, but I lean toward no - like Strange said above, we find virtual particle activity pretty much everywhere.

[JohnLesser]

I'm asking members of this society this question although its been almost a year since I last was active...i assure you...what i was getting at has been streamlined and revamped...I am goibg to stop this because i realize i am not following protocol so...

''Empty'' space can be viewed two different ways, a perfect vacuum or a void. If we could remove EVERYTHING from space leaving an empty volume with no physicality in it, then we must presume that empty space exists.

[KipIngram]

''Empty'' space can be viewed two different ways, a perfect vacuum or a void. If we could remove EVERYTHING from space leaving an empty volume with no physicality in it, then we must presume that empty space exists.

 

I'm not sure that's a valid concept - in order to perceive the space, at the very least the perceiver would have to be in the volume. Carrying on my thought from above, I think "empty space" would be what we perceive when there are no other entities for us to perceive.

[JohnLesser]

 

I'm not sure that's a valid concept - in order to perceive the space, at the very least the perceiver would have to be in the volume. Carrying on my thought from above, I think "empty space" would be what we perceive when there are no other entities for us to perceive.

I assure you a void and a perfect vacuum are valid concepts. The observer would not observe anything but experience ''darkness'' in a perfect vacuum or a void because of the obvious that there is no light. However the observer can determine there is still space by having the ability to move limbs

 

I am sure empty space ''exists'' but the problem would be how to empty that space.

[imatfaal]

I assure you a void and a perfect vacuum are valid concepts. The observer would not observe anything but experience ''darkness'' in a perfect vacuum or a void because of the obvious that there is no light. However the observer can determine there is still space by having the ability to move limbs

 

I am sure empty space ''exists'' but the problem would be how to empty that space.

 

It doesn't. Even empty space is full of spontaneously appearing particle/anti-particle pairs; alternatively we could say that even empty space is permeated by a field and there is a zero-point energy. We can even measure the "pressure" that this exerts by placing two plates very close to each other - this is one heuristic explanation of the casimir effect

[KipIngram]

I assure you a void and a perfect vacuum are valid concepts. The observer would not observe anything but experience ''darkness'' in a perfect vacuum or a void because of the obvious that there is no light. However the observer can determine there is still space by having the ability to move limbs

 

I am sure empty space ''exists'' but the problem would be how to empty that space.

 

But as soon as you move your limbs you are filling the space. The pieces of you count as stuff. But even without moving, you are in that universe. Even neglecting virtual particles it's now not an empty space.

[JohnLesser]

 

It doesn't. Even empty space is full of spontaneously appearing particle/anti-particle pairs; alternatively we could say that even empty space is permeated by a field and there is a zero-point energy. We can even measure the "pressure" that this exerts by placing two plates very close to each other - this is one heuristic explanation of the casimir effect

A common misconception, if the space is defined to be empty, then why are you ''filling'' the space with matter? We have definition to avoid confusion, a void is empty of all matter.

 

But as soon as you move your limbs you are filling the space. The pieces of you count as stuff. But even without moving, you are in that universe. Even neglecting virtual particles it's now not an empty space.

You are the one placing things in a void, may i suggest you check the definition of a void.

[imatfaal]

A common misconception, if the space is defined to be empty, then why are you ''filling'' the space with matter? We have definition to avoid confusion, a void is empty of all matter.

 

This is a physics forum - nature trumps definition. You can define space as to be empty and you have created a non-physical environment whereas in reality even the deepest void has virtual particles/zero-point energy field. We will often assume that space is empty as we don't care about a tiny number of virtual pairs (ie when dealing with planetary orbits) - but if you are dealing with the small scale and talking about the vacuum then you must not ignore the reality of the situation.

[Sriman Dutta]

An absolute empty space is purely hypothetical. It doesn't exist.

Almost everywhere there are photons and the presence of even a single photon would break the notion of EMPTY SPACE.

[Strange]

 

This is a physics forum - nature trumps definition. You can define space as to be empty and you have created a non-physical environment whereas in reality even the deepest void has virtual particles/zero-point energy field.

 

 

I don't know. There are zero energy solutions to the Einstein Field Equations (the Milne model, for example) that consist of an empty space-time. These are useful to understand how space-time behaves in various different situations. They are "unphysical" in the sense of not representing the universe we live in, but they are valid physical thought experiments.

[imatfaal]

 

 

I don't know. There are zero energy solutions to the Einstein Field Equations (the Milne model, for example) that consist of an empty space-time. These are useful to understand how space-time behaves in various different situations. They are "unphysical" in the sense of not representing the universe we live in, but they are valid physical thought experiments.

 

Exactly what I was getting at this section "We will often assume that space is empty as we don't care about a tiny number of virtual pairs (ie when dealing with planetary orbits)" but when you are dealing with EFE you are - perforce - dealing with the large scale and you can safely not care about the tiny interactions. This is where GR falls down - it works brilliantly on the large scale but there is no crossover to the microscale, there is no harmonious link up with qm/qft ; discussions of the void as completely empty space are necessarily dealing with the small scale and thus must engage with the quantum world. And as we are talking about fields as well then there is always the Higgs field to think about

[JohnLesser]

 

This is a physics forum - nature trumps definition. You can define space as to be empty and you have created a non-physical environment whereas in reality even the deepest void has virtual particles/zero-point energy field. We will often assume that space is empty as we don't care about a tiny number of virtual pairs (ie when dealing with planetary orbits) - but if you are dealing with the small scale and talking about the vacuum then you must not ignore the reality of the situation.

Virtual means they do not exist physically, also you can not change definition to suit or it leads to global confusion. The definition of a void is space completely empty of everything, putting things in makes it no longer a void.

 

This is a science forum! may I suggest you get your definitions correct

[imatfaal]

Virtual means they do not exist physically, also you can not change definition to suit or it leads to global confusion. The definition of a void is space completely empty of everything, putting things in makes it no longer a void.

 

This is a science forum! may I suggest you get your definitions correct

 

You do realise we can measure them? And the philosophical void empty of everything does not exist.

[JohnLesser]

 

You do realise we can measure them? And the philosophical void empty of everything does not exist.

If you can measure them, why refer to them as virtual?

 

You say a void empty of everything does not exist, what then do you propose is left if we could remove all the matter from a volume of space?

 

Take note I said all the matter.

[imatfaal]

If you can measure them, why refer to them as virtual?

 

You say a void empty of everything does not exist, what then do you propose is left if we could remove all the matter from a volume of space?

 

Take note I said all the matter.

 

Particle/Antiparticle Pairs come into existence and vanish very quickly - they are a fluctuation that shouldn't happen according to classical physicals but must happen according to quantum field theory.

 

Classically we can remove everything from space (the classical vacuum) - but this is a approximate situation as you will always have blackbody photons, and quantum field fluctuations. Even in a toy universe with no matter and no radiation you will still have pairs popping into existence - a zero point energy