Pure Vacuum can exist? True or False?

[rainman]

Can a Pure Vacuum or a perfect vacuum exist in our universe? If so, is that what existed before the Big Bang? Also, is a pure vacuum...absolute nothingness...necessary in order for matter/energy to move? For example, if a photon moves...must it move into pure vacuum? or is it possible for matter and energy and matter/energy to move into each other's location without dislodging the current occupant of that location?

[Pandaemoni]

Can a Pure Vacuum or a perfect vacuum exist in our universe? If so, is that what existed before the Big Bang? Also, is a pure vacuum...absolute nothingness...necessary in order for matter/energy to move? For example, if a photon moves...must it move into pure vacuum? or is it possible for matter and energy and matter/energy to move into each other's location without dislodging the current occupant of that location?

No. There will still be vacuum fluctuations.

The Big Bang was not an explosion in space that filled it with stuff, it was an explosion of space and stuff. "Before the big bang" doesn't even work, because there is no time applicable to the universe other than that which the Big Bang created. The Big Bang created all the space and all te time that we know of.

[John Connellan]

No. There will still be vacuum fluctuations.

But surely the definition of "fluctuation" indicates that there might be times where a point in space will be momentarily, vacuum?

Or is there a law which states that the zero point energy is never actually zero?

[StrangerInAStrangeLa]

-=-

Define vacuum.

[Rav]

It is amazing how fashionable it has become to discuss this topic. It's certainly been a favorite of mine I think someone is eventually going to get irritated though if this topic pops up in every science forum simultaneously, as it seems to be in danger of doing. Anyway...

As far as I am concerned a pure vacuum can't exist. This is because I am convinced that space is a fabric of some kind, which means that if a vacuum contained space and nothing else, it wouldn't be empty. It would be full of space.

This is why I keep saying that the idea of a vacuum is only useful so far as it relates to the absence of something in particular rather than the absence of absolutely everything.

[John Connellan]

As far as I am concerned a pure vacuum can't exist. This is because I am convinced that space is a fabric of some kind, which means that if a vacuum contained space and nothing else, it wouldn't be empty. It would be full of space.

I dont think that's the definition of vacuum though is it? That would just be "nothing"

[Rav]

I dont think that's the definition of vacuum though is it? That would just be "nothing"

Exactly. Sort of. It's more correct to say that it wouldn't be anything than it is to say that it would be nothing.

[GeoffP]

But surely the definition of "fluctuation" indicates that there might be times where a point in space will be momentarily, vacuum?

Seems reasonable. Perhaps it's how you define the space in question. I think both you and Pand are right, but from different perspectives. Like Fisherian and Wrightian evolution.

[John Connellan]

Exactly. Sort of. It's more correct to say that it wouldn't be anything than it is to say that it would be nothing.

Well, vacuum is not nothing. It is still comprised of space in it's 3 dimensions. "Nothing" would be what is outside our universe.

[Rav]

Well, vacuum is not nothing. It is still comprised of space in it's 3 dimensions.

Indeed. This is more or less what I argued myself. You can't define a vacuum as the absence of absolutely everything because then it wouldn't be a vacuum. It wouldn't be anything.

"Nothing" would be what is outside our universe.

I apologize for being so pedantic, but this is important. Your statement should be rephrased like this: There isn't anything outside of our universe. You wont find "nothing" anywhere. It doesn't exist. There is no such thing.

Please forgive me for bending my own rule in order to demonstrate why it is important to follow it :P

[DRZion]

Is there any way to produce some kind of interference so that quantum fluctuations do not arise?

[quantum_wave]

This topic is getting popular as Rav points out. And I like to put my 2 cents in as well.

I just wrote a post over in Pseudoscience that included a mention of de Sitter. He did a solution to the EFEs where he took out all matter. Since the discussion is here, and not very many read my posts in Pseudoscience, here is the part about de Sitter: "I guess if de Sitter was still around he would still be taking the mass out of alternative cosmologies to see what makes them tick. This post compares what he would find if he took the mass out of [an unknown cosmology]. Remember that one solution to the EFEs was de Sitters massless expanding geometry. In GR, the geometry of spacetime originated with the same event that accounts for the presence of matter and energy in the universe. In other words when he took the mass out of the fabric of spacetime we are left with geometry where space and time are coupled and space is being added without upsetting the geometry.

Of course that was just a thought experiment that follows the logic of GR where mass warps spacetime but spacetime itself is independent of the presence of mass."

That sort of says what spacetime is without matter, i.e. empty spacetime. It is a solution to Einstein's field equations that points out that the geometry of spacetime is what makes the inertial connection between all objects of mass and exists whether there is any mass or not.

[Bizza]

Sorry to interject here, but when did "Space" or "Time" ever become a "fabric"? Without mass/matter, there is no such thing as 'reference points' (important for observing "change"= "time"). "Space" is somewhat of a semantic word used to describe what we can't detect, yet! Because of this, I truly don't believe there is, nor ever was a "pure vacuum".

It is based on the most basic presmise that;
"Something cannot come from nothing". (Even in near-Planck limits, but never within).
If this is so, then there must always be (and has been) "something" for all eternity and this leads one to logically conclude that "nothingness" (aka "pure vacuum") is not possible, let alone fathomable.

Just a thought.

[Dywyddyr]

Sorry to interject here, but when did "Space" or "Time" ever become a "fabric"?

Isn't spacetime the fabric that's distorted by matter?

It is based on the most basic presmise that;
"Something cannot come from nothing".

Yup.
With the laws of physics as they are now.

If this is so, then there must always be (and have been "something" for all eternity

So not necessarily.

[Bizza]

Isn't spacetime the fabric that's distorted by matter?

That's the misconception (in my view). How can something that has no fabric at all (like "spacetime") be "warped"? It's the actual matter within (the undetected existents) that are warped and thus, the concept of "time" and "space".

[Dywyddyr]

That's the misconception (in my view). How can something that has no fabric at all (like "spacetime") be "warped"? It's the actual matter within (the undetected existents) that are warped and thus, the concept of "time" and "space".

Um, isn't gravity explained as warping of spacetime BY matter?

[Bizza]

Um, isn't gravity explained as warping of spacetime BY matter?

We don't even know what "gravity" is. It is suspected that it may be the mythical Boson, but even THAT is still "matter". So where does the absence of matter leave the so called "fabric" of "space" and "time"?

[Dywyddyr]

We don't even know what "gravity" is.

Correct, but one explanation is given above.

It is suspected that it may be the mythical Boson, but even THAT is still "matter".

The Higgs?

So where does the absence of matter leave the so called "fabric" of "space" and "time"?

Flat and undistorted.

[quantum_wave]

We don't even know what "gravity" is. It is suspected that it may be the mythical Boson, but even THAT is still "matter". So where does the absence of matter leave the so called "fabric" of "space" and "time"?

That leaves us with one version of a de Sitter universe, one of many solutions to the field equations which are part of GR which is the current consensus cosmology.

Correct, but one explanation is given above.


The Higgs?


Flat and undistorted.

And the Higgs field is the source of matter where I think the Higgs boson decays into the fundamental particles with mass. I guess that would mean that in the standard model of particle physics the missing Higgs boson would have mass that is imparted to the particles as it decays.

[Bizza]

Correct, but one explanation is given above.
The Higgs?

Maybe the Higg's Boson, perhaps? But at the end of the day, when you mention "gravity", we must understand what it is first. We just don't know, but it is there and very detectable. What we use to detect this IS 'location or proximity = "space"' within 'changes in reference points = "time"'. Please, don't get me wrong, because I've been discussing this with the best of them and even they get frustrated by questions like this.

If you think about it, "time" is a "fundamental unit" of measure (measured from physical matter like the Caesium atom). Not a fabric of any kind whatsoever. "Space" is also just the absence of something or a geometrical construct (mathematically) of that absence.

At the end of the day, matter/mass is KING in this universe and everything else (including "Energy") are the measures of these existents.

I know it's radical, but that's just my 2 cents.

Flat and undistorted.

Or "nothing"?