I don't know if there is enough knowledge acquired yet about Bose-Einstein condensates to answer my question, but here it goes....

From what I have read about the subject, I understand that the atoms in such a condensate appear to occupy the same space.

If this is so, is there a limit to the number of atoms that can occupy that same space?
How would this affect the actual matter density of the element in question?

There is enough information and the number of atoms able to occupy the same space, it would appear, is infinite (whatever that means).

Density-wise it might be a really good way to think about the universe before the Big Bang and Inflation.

Are you implying that if we were to cool off a really high amount of atoms into a bose-einstein condensate, we could increase mass infinitely leaving the volume to a near zero, therfore creating a gravitational singularity?

Wow. That's an interesting thought.

I could picture that being used in a sci-fi piece explaining how an advanced civilization manages to build their power sources. Just feed a large enough amount of matter into a condensate until it eventually is big enough to start eating it's own environment with gravity.

Of course, the near-zero temperature would need to be maintained, and that would be pretty tough in something as energetic as a black hole. (It also begs the question, does a black hole evaporate faster when it's hotter? We know it evaporates more and more quickly as it shrinks, and that probably equates to heat somehow.)

(Yes, I know this post probably belongs in the Sci-Fi subject area, but this was where it fit. )

m

This is weird and confusing.

Isn't it true that protons, neutrons, and electrons, being fermions, cannot form a Bose-Einstein Condensate as they prohibited by the Pauli exclusion principle from occupying the same quantum state? - and that only bosons can do this.

Ok, I found something in Wikipedia:

"Particles composed of a number of other particles (such as protons, neutrons or nuclei) can be either fermions or bosons, depending on their total spin. Hence, many nuclei are in fact bosons. So even though the main three massive subatomic particles i.e. the proton, neutron, and electron are all fermions, it is possible for a single element such as helium to have some isotopes that are fermions (e.g. 3He) and other isotopes that are bosons (e.g. 4He). (3He) is composed of one neutron and two protons [PNP]. Likewise, the deuteron (2H), which is composed of one proton plus one neutron [NP] is a boson, while the triton (3H), which is composed of two neutrons plus one proton [NPN] is a fermion. The deuterium atom composed of three fermions (proton+neutron+electron)is a fermion, while its nucleus [NP] when separated from the electron is a boson."

It's still confusing though!

Well fermions would create a fermionic condensate
While bose-einstein is called a bosonic condensate
Which both share similar properties

http://en.wikipedia.org/wiki/Fermionic_condensate

So, MrBiGG78, Dan Summons' statement, below, is wrong?

"No analogous phenomenon occurs for two or more fermions, which are prohibited by the Pauli exclusion principle from occupying the same quantum state"

Dan Summons, Physics Undergrad Student, UOS, Souhampton

Red ... follow this link:
http://en.wikipedia.org/wiki/Fermionic_condensate

To address the original question ... yes in theory one could create a black hole this way. You might, however, run into a few significant engineering issues on the way there.

I'm far from being a particle physicist (I just read a lot) and I never implied that Dan Summons is wrong...


Here is the excerpt I would refer to...

"It is far more difficult to produce a fermionic superfluid than a bosonic one, because the Pauli exclusion principle prohibits fermions from occupying the same quantum state. However, there is a well-known mechanism by which a superfluid may be formed from fermions. This is the BCS transition, discovered in 1957 by John Bardeen, Leon Cooper and Robert Schrieffer for describing superconductivity. These authors showed that, below a certain temperature, electrons (which are fermions) can pair up to form bound pairs now known as Cooper pairs. As long as collisions with the ionic lattice of the solid do not supply enough energy to break the Cooper pairs, the electron fluid will be able to flow without dissipation. As a result, it becomes a superfluid.
"

Cooper pairs are bosonic in nature and therfore the Pauli exclusion principle doesn't apply anymore. Therefore, at sufficiently low temperature and high pair density, the pairs may form a Bose-Einstein condensate.

Thanks for the link MrBiGG78 & DA. I don't mean to flog this, but at first sight, some of the available info looks contradictory. I think I have it at last (don't I?): the fermions first form Cooper pairs, then these are able to form a condensate.

In some cases what you will find redewenur is that multiple fermions can bind themselves into a collection that is bosonic.

So the condensate isn't the fermions but rather the bosonic bound state of the fermions.

Yes, I think I got that at last DA. It gets around the Pauli exclusion principle. Thanks.

Thanks again, MrBigg, for your help.

It's not always that the nature of the info is difficult to understand, but when relatively new research is involved, some articles are obsolete (and therefore seem contradictory). As for Dan Summons, it seems that he was right, but what he said was misleading since he made no mention Cooper pairing. This may be because it wasn't achieved until 2003.

Wow, google your name and you might find yourself quoted on a physics forum!

(Yes, original answer was posted 2001 or something like that....back when i was an undergrad)

It's an honour to have you drop by.

All,
This is my first post so please go easy on me .
Anyhow,
I was thinking that we could really use several concepts here to
create a very nice energy cell; let me know what you think.
Take two BEC's grow them quite large - you will get (I think, this is all brainstorming) at some point a "soft singularity" something that acts like what Steven Hawking calls a black hole, but is not black (SH's black holes do radidate, and eventually evaporate), but more like a pinched off area of space time. (again I'm referencing his Brief History of Time, old but I think has good ideas.) Given that you make two of opposite spin (even a BEC has a spin right? (not sure), can keep them close, the virtual particle pairs they generate and absorb (if they act like SH says singularities do) would hopefully be of opposite charges. And there you have it, a very nice battery with anode and cathode. Now all you need is a way to take advantage of the current flow or whatever energy is cycling through this system. Hmmf. Sure would beat fusion which we know is hard to create here on Earth. I figure its a subtler approach, and sometimes they can be best. I know this is way way out there, but hey maybe some of you can lend a hand?
Thanks!
-Amnion

P.S.
Also if BEC's have a quantum state/spin, perhaps we can entangle them like photons and get some energy flow going with two of them perhaps entangled at "90 degree" angles, sort of like polarized light? Hmmf.

The amount of energy currently required would make this remarkably inefficient as an energy cell.

Have you looked at the investment required to cool something down to, essentially, absolute zero?

I didn't before, but thanks for that insight, it helps me think more clearly. Looking at this idea as its taking shape, it seems like its something further off, but I think as it comes closer to reality, we will find that it not so hard to do, but I agree, we will have to build towards this goal, no invention goes from nonexistence to existence without using others' ideas.
Right now laser/evaporative cooling allows us to reach BEC's, superatoms, liquid helium, and other liquid gases get us to BES's, superfluids. IMHO the best place to cool something at the moment is to start this sort of project on the dark side of the moon, or in deep space. These places are always very cold, which is a good start. Then we make it colder via the use of lasers/evaporative cooling, and soon via methods that we haven't thought of yet. Besides, if you are playing with a super high energy reactor, it might be wise to experiment far from Earth, you don't want this going wrong in our backyard. Maybe the Moon is too close, but we don't have the technology right now to jump to a far space and back, so I guess we will have to create our "lab" somewhere on the moon or at first Antarctica.
-A

Amnion: "the best place to cool something at the moment is to start this sort of project on the dark side of the moon...so I guess we will have to create our "lab" somewhere on the moon"

Remembering, of course, that the moon has day and night, and that there is no permanent 'dark side'.

Amnion: "..dark side of the moon, or in deep space. These places are always very cold, which is a good start.."

I think you'd be surprised how warm (in a relative sense) these places are. If you put a thermometer is deep space and allowed it to cool (this would take a really long time), and kept it isolated from all sources of light and background radiation, you'd find it would never read cooler than 2.7K.

The first Bose-Einstein Condensate (1995) had a temperature less than 100 billionths of a degree above absolute zero (100 billionths of a degree kelvin) i.e. a lot colder than outer-space!

Thanks,
D.

Amnion certainly has a point, though, in that the temperature gradient would be small. Would there be vast difference in energy requirements between the following:

(1) Cooling a mass in deep space from 2.7K to 0.2K

(2) Cooling the same mass on Earth from room temperature, to room temperature minus 2.5K

How much energy would it take to get the required quipment and energy source to whatever location in order to be able to engage in such a cooling venture?

Deep space does not grow lasers and containment vessels.

It is an idea for a century well into the future ... not this one.

Yes, DA, it won't happen tomorrow; but I intended the question to be hypothetical and to serve soley as a basis for discussing a key point: the temperature gradient.

I'll simplify the question, and reverse it, to avoid confusion:

Would it still require 4.1855 joules (1 calorie) to raise the temperature of 1g of water (ice) from, say, 1.7K to 2.7K, or is the physics different at close to absolute zero?

I don't think the physics is different but the amount of effort required gets larger in that it only takes the passing gamma ray photon, potentially, to make a mess of things.

One thing lost will be the shielding of the Van Allen belts and the atmosphere.

But I truly don't know how significant that would be.

Good points everyone! I hope we can keep this thread going in some form. For now, lets just say we want to create a BECS. ("BECSingularity, and by that I guess I mean a gentle way to create a region of infinite curvature of space-time). Again, I'm just going out there, so please feel free to add correction/input of any kind. So, do do this we need a VERY cold place with say a very strong magnetosphere. Hmm...I can think of one possible place, Jupiter, its got this HUGE magnetosphere and its pretty cold in places... Another place I suppose would be in the Oort belt, but hey, that's really far away. I'm not sure, but if we can haul some junk out somewhere cold and shielded, I think we could start some really cool experiments. Maybe instead of worrying so much about hauling mass, we can use some Newman machines to make what we need, when the nanomachines get there. In any case, first one to create BEC of critical mass should definitely get a cookie, and a Nobel prize to boot!
Later,
Amnion

Amnion, on the face of it, the topic is stepping well into the realms of science fiction. We can safely say that, as far as practicalities are concerned, we're talking about, if not the impossible, then the extremely improbable. (Anyway, I think nanobot von Neumann machines would be more useful )

Nevertheless, it is interesting to consider where in the solar system one might find temperatures close to 2.7K without going too far from the sun. Obviously, lower temperatures would be easier to find at greater distances from the sun; but lets look at some options:

Amnion: "...I can think of one possible place, Jupiter, its got this HUGE magnetosphere and its pretty cold in places..."

No, not Jupiter; it radiates too much heat.

The other gas giants and their moons may also be radiating too much heat.

Amnion: "I'm not sure, but if we can haul some junk out somewhere cold and shielded"

"Shielded" could mean in a penumbra, right? Maybe somewhere relatively nearby like an asteroid in the asteroid belt - especially one that's not rotating. At least it would be unlikely to radiate much heat, and would be far from other heat sources (except for the sun).

If not, you might consider the Kuiper belt. More accessible than the Oort Cloud - just down the road by comparison - and it must be pretty chilly.

@redewenur - Correct, we are getting into the realm of "Science Fiction". However, in my mind science fiction is a way for us to describe possibilities. From what I've observed, the more popular and long lived a science fiction idea (think meme, natural selection of the truth) the higher probability of the idea becoming "reality". The difficult part is knowing the time frame in which they will come to pass. The prediction of future events seem to obey Heisenberg's uncertainty principle in that if we know more certainly What is going to happen, the When gets harder to pinpoint, and conversely, knowing that "something" important is going to happen at a certain time limits our ability to determine the nature of that event . If you view the theory of zero point energy generators, its been passed around quite a bit. Because of the greater frequency of such a concept in the human consciousness on this planet, I believe that we are coming closer (on a logarithmic scale) to the realization of what was formerly science fiction.
To talk about ZPG's, I'm sure that when the time is right, we will find the right dark, cold place to build our apparatus.
-A

Thats very interesting. So are you implying that this new form of matter can never exist, nor has existed anywhere in our universe?

That it's only a temporary result of our human experiments in a low temp laboratory in trying to achieve the hyper-theoretical absolute zero?
No more super heavy (black hole type) of dense atom clusters, and other semi-science fiction ideas?
Shame, ....if true I'm really dissapointed.

--------------------
"You will never find a real Human being - even in a mirror." .....Mike Kremer.
.

It does seem that the coldest place in the universe is in a lab on this planet.

But I'm not sure that is necessarily the only condition under which a Bose Einstein condensate can be created.

It is just the only one of which are currently aware.

Time will tell.