Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: yor_on on 14/09/2010 20:40:08
-
"The coldest temperature in space is about 3°K above absolute zero. This is defined as the Cosmic Background (or Microwave Background) Radiation that was first detected by Penzias and Wilson using the Holmdel Horn Antenna in New Jersey, USA in 1965. This radiation quite literally is the echo of the Big Bang. Assuming you're measuring the temperature of pure space, or an area in which there is no matter that could absorb the sun's radiation and thereby heat up, the temperature would be -459° Fahrenheit, -273° Celsius, or 0° on the Kelvin scale."
So whatever space is, its certainly cold enough to become something boson-like?
-
Do you mean BEC-like (Bose-Einstein condensate?) Bosons are particles that, unlike most matter we see every day, can stack on top of each other without a problem. For example, in an atom there are a limited number of slots for fermions per energy level, so that if you keep adding electrons, they fill out higher and higher energy levels. If these electrons behaved like bosons, the could all sit in the same lowest energy level without bumping each other out.
A BEC is the thing you can make by cooling bosons down enough that they all essentially sit in the same quantum state. If that's your question, then no, I don't think a vacuum is like a BEC, since a BEC is made up of real particles, while the vacuum isn't.
-
Space is something right?
It has properties too, what ever it is we see it as having a distance f.ex. We also say that it's cold. Now, the discussion of coldness seems to make possible some remarkable transformations in both matter and light, they all become 'boson-like' right?
Should we stop there? To say that space have nothing to do with it?
Are we sure?
Weird stuff huh :) What about times arrow, when a condensate becomes? Does it disappear?
And how can light be 'stored' in that condensate? Does the condensate in some manner becomes the 'light' at that time? And what differs a condensate from space? Does it have any parts resembling an atom at all? Isn't the reason we call it a 'super-atom' more the way it behaves as an entity, also knowing and expecting that it still will transform back into singular atoms as soon as we warm it up?
But you're right, thats not a vacuum, if there is some resemblance then it need some other transformation to become one, and there time is my suspect :)
I really need to get it straight, huh :)
Awh ...
==
And yes Bose Einstein, not Boise Einstein :)
Sh*, another thingie to clean up somewhere..
Senility my middle name ::))
-
It has properties too, what ever it is we see it as having a distance f.ex. We also say that it's cold. Now, the discussion of coldness seems to make possible some remarkable transformations in both matter and light, they all become 'boson-like' right?
Temperature has nothing to do with defining bosons. A boson is a kind of particle that's basically defined by the fact that they can occupy the same states as each other. The other kind of particle is a fermion, which can't do so. If we all drove Boson cars, we wouldn't have to worry about parking spots, since we could all park in the same spot at the same time. Sadly, we drive Fermion cars, so once you occupy a spot, I have to park elsewhere. Temperature doesn't come into this definition.
The BEC is what happens when you cool a Boson gas down enough that nearly all the particles go into the same low-energy state. If you do the same with a Fermionic gas, this won't happen.
A Boise-Einstein condensate is what happens when you make one of those in Idaho.
-
Nope, we transform fermions to bosons, well as I understands it. Granted that it's not all fermions we can do that (the same way) with, but that may just be the way the puzzle goes. For example "A fermionic condensate is similar to the Bose-Einstein condensate but composed of fermions. The Pauli exclusion principle prevents fermions from entering the same quantum state, but a pair of fermions can behave as a boson, and multiple such pairs can then enter the same quantum state without restriction." Fermionic condensates. (http://en.wikipedia.org/wiki/State_of_matter#Bose-Einstein_condensates)
and BEC - condensates. (http://www.spacedaily.com/news/physics-04n.html)
So, yes JP, you're right.
And no JP, you're wrong :)
So what, I contain multitudes :)
Heh.
-
You had to go there. :)
I was hoping to ignore Fermions acting like Bosons, since that gets complicated. You're right--they can behave like Bosons in certain cases, but I'm almost certain that you can't just can't cool down any old bunch of Fermions and get them to behave like a BEC.
Anyway, space isn't particles, so I don't think it will behave like Fermions or Bosons. Particles floating around in space will, but space itself won't. (The virtual particles popping in/out of space are Fermions of Bosons, but since they're virtual, I don't think they can condense either.)
-
Well yes JP, I agree. But it all comes back to time for me. Space is so weird, think of it like me and you'll see why. That matter have a distance might be explained by it's 'matter' and have to take 'place' according to the Pauli exclusion principle, which in reality just are a 'acknowledgment' of the way 'reality' seems to treat matter and so something more of a 'archetype', meaning something we (through experimentation today) take for granted as an 'absolute truth', similar to the way we accept that one and one will make two.
But space?
Why does it have a distance?
-
Space is something right?
Something in what sense?
I agree with JP that space isn't particles, and in fact, I'd say that space isn't something but somewhere; space isn't made out of something, which is where you seem to be heading towards (or if you prefer, what you seem to be heading towards).
But it is interesting that you ask "Why does it have distance?", for what is distance, and what is distance made out of?
-
I'm unsure what you mean by "space." Do you mean the vacuum of outer-space? Or do you mean the dimensions of space?
The vacuum is simply where there isn't anything (or much), which is why it's cold. There's nothing to excite.
The spatial dimensions have distance for the same reason that the temporal one does: metrics.
-
Well, to me space is both. It's a vacuum in that we define it as 'empty' and it contain 'distances' meaning that even though not being anything measurable in a normal sense, except through its absence, it still exists and have an extension in SpaceTime. As for it being something, it's for example the place where we expect inflation to take place as well as the place for such strange phenomena as the Rindler effect, aka virtual photons becoming observable due to velocity. So to me it is 'something'? Even though I don't know exactly what.
==
And yes LeeE, that's a very good question :)
What is distance?
-
Space is something right?
Something in what sense?
I agree with JP that space isn't particles, and in fact, I'd say that space isn't something but somewhere; space isn't made out of something, which is where
Absolutely, that is the reason we refer to it as "Space/Time".
The too concepts can't be defined one without the other.
...............Infy, AKA; Ethos
-
Well, as i said I don't know what it is :)
Just that it contain 'distances' and allows for a lot of strange phenomena, even when containing 'nothing'.
And if you don't agree to that be more precise in where you think I'm wrong please. I know that it's a part of our universe already :)
-
That's like saying coldness is something, I suppose. When something cools it's because energy is leaving the object. Not because it's gaining something else. In the same way, the vacuum of space is what remains when matter (& energy) aren't there.
Also, calling the dimension of space the same as the vacuum of space is like calling coldness the same as temperature, isn't it?
-
Yep, as it is a 'nothing' according to what we observe 'normally' with exception taken to those those experiments proving 'virtual photons' and/or 'vacuum energy' it have no 'moving parts'. Without those there can't be a temperature, and neither can we prove any 'normal', for us visible, photons existing. So a light quanta 'traveling' in space will need an interaction with matter to exist, as far as I understands it?
-
So there could be tons of light out there interacting with things other than normal matter, huh?
-
Now that's a good one :)
But it depends on how you look at light.
Let's assume that virtual photons, vacuum energy, and 'ordinary photons' are expressions of the same thing, only times arrow forcing us to differentiate between them. Then let us assume that they 'travel' and also can, weird thought :), be a field, as they seem to be when defining it as a vacuum energy. If so, sure, immeasurable amounts of light might exist 'hidden' inside what's not there, aka the vacuum.
Let's now change our premises somewhat and decide that for light to exist you need an interaction, like us seeing it, and that without that it don't 'exist' at all. Then nope, whatever we see and act on will need to be a relation. And looking at it that way nothing 'exists' on its own. Then it's only in its interactions we can observe that light 'existing'. And then a 'field' starts to make more sense too, as a field could naively be seen as being everywhere, having no movable 'parts' except when acted upon.
But? I don't know. Radiation in form of waves etc is one possibility. We say that waves don't need a conductor, meaning that they can travel in a 'nothing' like deep space, and as light intrinsically is timeless, not lose its energy until in its interaction.
Maybe.