[dentstudent (OP)]

Here may be some innocent questions....

Can we make an absolute vacuum?

My understanding of absolute zero is that it can only be achieved in the absence of any particles (you know, everthing), thus the total absence of energy. Is it possible to combine these two to create absolute zero?

[DoctorBeaver]

There must also be a total absence of energy.

According to QM there is no such thing as absolute nothingness. Even a seeming vacuum is teeming with virtual particles that are created spontaneously and then annihilate each other.

You may have heard of the Casimir effect, which relies on vacuum energy.

This all means that there cannot be any such thing as a total vacuum so, consequently, absolute zero can't be achieved.

[dentstudent (OP)]

Can it be done on a sub-atomic scale (this is the smallest thing I can think of - I'm sure there's smaller!)? If you can make a space smaller than anything can fit into it, virtual or not, then there must be an absence of energy?

[DoctorBeaver]

String theory points to strings being the smallest "things". These are of the order of 10^-33cm. In the case of closed strings (loops) there is obviously a gap in the middle (like a doughnut or polo mint) but whether it is totally empty or contains something...

I've not come across any literature that says there is anything within the loops, but maybe 1 of the physicists here can enlighten us.

[Soul Surfer]

Absolutes are always difficult things and there is very little difference between a very good vacuum and an absolute vacuum and very cold and absolute zero

It depends what sort of vacuum you are talking about.  The classical vacuum could in theory be absolute when there are no particles in it so if I built a conducting box in deep intergalactic space where there is about one atom per cubic metre and did not catch that atom it would be a pretty good vacuum particle wise the conducting box would screen out the cosmic microwave background radiation and if I cooled the box down to a few millionths of a degree above absolute zero using cryogenics and adiabatic demagnetisation it will be pretty well there for a while but the difference betwennthat and the intergalactic space that was there would be very small.

Now if it was a quantum mechabnical vaccuum you have to consider all the potentialities at high energy in the space and it looks like a roiling furnice if you look for short enough periods of time!

[DoctorBeaver]

Now if it was a quantum mechabnical vaccuum you have to consider all the potentialities at high energy in the space and it looks like a roiling furnice if you look for short enough periods of time!

I think that's what I said - sort of(ish)

[another_someone]

String theory points to strings being the smallest "things". These are of the order of 10^-33cm. In the case of closed strings (loops) there is obviously a gap in the middle (like a doughnut or polo mint) but whether it is totally empty or contains something...

I've not come across any literature that says there is anything within the loops, but maybe 1 of the physicists here can enlighten us.

But if you have a region of space devoid of anything, how do you measure it?  The moment you try and measure nothing, you have to have something to measure it with, so it is no longer nothing.

[another_someone]

Absolutes are always difficult things and there is very little difference between a very good vacuum and an absolute vacuum and very cold and absolute zero

Does this not rather depend upon your baseline.

Based of STP, we can get very close to absolute zero temperature and pressure; but if you take the core of a star, even STP is looking fairly close to absolute zero; while iof your baseline is intergalactic space, then getting 'very close' to absolute zeroes becomes more challenging.

[dentstudent (OP)]

String theory points to strings being the smallest "things". These are of the order of 10^-33cm. In the case of closed strings (loops) there is obviously a gap in the middle (like a doughnut or polo mint) but whether it is totally empty or contains something...

I've not come across any literature that says there is anything within the loops, but maybe 1 of the physicists here can enlighten us.

But if you have a region of space devoid of anything, how do you measure it?  The moment you try and measure nothing, you have to have something to measure it with, so it is no longer nothing.

Does this mean that even if it were possible to have absolute zero, that it could never be measured, and hence can never be proven to have existed?

(sorry - and what is STP? I only know it as an oil additive! er, space, time something?)

[DoctorBeaver]

Measuring it would certainly present a slight problem  []

STP = Standard Temperature & Pressure

[lightarrow]

Absolutes are always difficult things and there is very little difference between a very good vacuum and an absolute vacuum and very cold and absolute zero

The first is very different from the second. According to some theories, the difference in energy density between vacuum and absolute vacuum could be responsible to the huge Dark Energy, which accelerate the universe's expansion.

[JimBob]

Moderator's Note: This topic was split into two topics and is discussed in an alternative form in "What is non-space and can an absolute Vacuum exist?" In "New Theories"

[gfellow]

Absolutes are always difficult things and there is very little difference between a very good vacuum and an absolute vacuum and very cold and absolute zero

The first is very different from the second. According to some theories, the difference in energy density between vacuum and absolute vacuum could be responsible to the huge Dark Energy, which accelerate the universe's expansion.

Is it possible to create an absolute vacuum? It is an interesting speculation, and I have enjoyed reading contributors who have posted on this thread.
Absolute vacuums undoubtedly have a profound impact on the behavior of the universe, and I believe that in the not-too-far future it will be possible that absolute vacuums will transition from the merely theoretical to an observational level.

It seems reasonable to assume that absolute vacuums are not empty space, but volumes devoid OF space.
Within such volumes temperature and time would not exist. The external universe does not like this, and borrowing a phrase from Benedict Spinoza, "Nature abhors a vacuum."
How does the universe express abhorrence? It implodes upon the AV in an attempt to equalize the pressure.
What is the nature of such an implosion? It is gravitational - which is interesting because it gives us a tantalizing hint of gravity in action without a corresponding quantity of mass.
What proofs can one point to that the implosion is gravitational? Consider a cup of stirred coffee. The differential of high pressure towards the side of the cup in contrast with the low pressure center produces a miniature distortion in space time, and a lump of orbiting cream will swirl around the center, obeying Kepler's second law of planetary motion, a clear hint that pressure differences contain a gravitational component.

It will be demonstrated that under special circumstances matter can configure itself to allow the existence of absolute vacuums, or non-space. This can occur in a high energy plasma imbued with a dynamo effect.
I predict that in an experiment where a gravitational sensor is placed in the vicinity of a z-pinch discharge, the plasma will exhibit an incremental increase in the force of gravity that otherwise cannot be accounted for.   

[yor_on]

There is this strange possibility of 'negative energy' to virtual particles'. So maybe if you could create a state where the 'negative energy' would take out the 'positive energy' you would have a 'space' without 'energy'. Not that I think it's possible myself but?