[DoctorBeaver (OP)]

Gawd! I owe her an apology.

I remember your saying that she had a PhD in particle physics.

It is OK - she often gets mistaken for a 'bloke' and doesn't generally hold a grudge - in fact I think she quite enjoys revealing that she is in fact a large lesbian lady (doesn't half knock the religious bunnies off their stride in debates)

I can imagine!  []

[yor_on]

Lightarrow:)
thanks.

I checked it out after you wrote and you are definitely correct.
I just looked at it out of the aspect of FTL.
Thats the problem with not having a good grounding in 'basic physics' I presume.
no matter how 'hungry' one are:)


Especially the way you set up and explained your equation/formula.
It's very refreshing to see it like that.
It makes it that much easier to put into context.

---
Lost DB?
To me you seem to 'find yourself' rather quickly:

[lightarrow]

Lightarrow:)
thanks.

You're welcome! For completeness, I have added a little consideration to that post.

[lyner]

yor_on

But if I choose to see photons 'particle-wise' and then question the way they will act if so?
Then that also works as far as I know.
It is not forbidden, is it?

Not 'forbidden' but I should say that you can't demand an answer in those terms. I don't know of a way to explain diffraction (photons, electrons or anything) if you don't take the wave approach. Likewise, I don't see an explanation can be made without thinking about waves here, either.
Why do you want to 'insist'? Standing up in a hammock is not the best way to make love, either.

I could get on my hobby horse here and say "how can you describe something like a photon unless you specify its characteristics in more depth than just calling it a particle?" If you can do that, then you may come up with the answer yourself.

[yor_on]

SC

I would say that it goes back to what we call matter and light?
And my own desire to understand it, same as yours I guess:)
You say that you are happy with a wave approach, and I agree that it makes a lot of phenomena more easily understood.
Like red shift when climbing up a gravity well. or tunneling.

But I am matter, and so are you, and I see waves every day, but that's not me.
To me there is a difference, so I want to see how far I can get it together:)

It's my mind game, it keeps me from getting bored, and let me discuss with interesting people what I find the most fascinating subject ever, spacetime.

Be warned (s)he who starts to think will easily find it becoming a habit.
Ah, sort of?

And its better than discussing your new car, don't you agree:)

[DoctorBeaver (OP)]

I'm lost  []

Where? Ah, yes, if you knew it, you wouldn't be lost... []

I got lost when BEC was mentioned

Bose Einstein Condensate. Is a cloud of extremely cold atoms, prepared and confined specifically, through which light propagates at a cyclist's speed. It's quite similar to the fact light travels at lower than c in glass or water.

I think there's more to it than that. What about the Pauli Exclusion Principle? Don't the fermions in a BEC behave like bosons? That's a point - does the particles' spin change in a BEC?

I'm at a sort-of halfway house with BEC (as with a lot of other things). I've read and understand the low level stuff but I can't understand the mathematical treatments that explain it in depth. I wish there was a site that explained things in more depth but in idiot language (if that's possible).

[lyner]

But I am matter, and so are you, and I see waves every day, but that's not me.

There you go again!
If the electrons inside you were not waves, as well, then why don't they fall into the nuclei of their atoms?

You have to open your mind, `Grasshopper' or you will never come to terms with this stuff.

[yor_on]

Yes Sempai

That is in fact a very good question.
If someone would like to do a 'take on it' from a 'particle' perspective I'm all ears.
(quite handy when it comes to flying)

Otherwise I will have to think...
A lot....

--------

But I never said that waves shouldn't be counted in, have I?
If I left that impression, I didn't mean it.

What I am unhappy with is explaining matter as waves and then leave it there.
It reminds me of alchemy in where you define numerous imaginative properties to objects and then from some lofty perspective say 'as above so under'.
It may describe relations better but it does not take a grip on what is the difference between matter and light.
I can't walk through a window pane.

(well I can, but not without breaking it:)
But I am trying to see what unify light with matter.
Like momentum
And spacetime geometry/geodesics.

[lightarrow]

Bose Einstein Condensate. Is a cloud of extremely cold atoms, prepared and confined specifically, through which light propagates at a cyclist's speed. It's quite similar to the fact light travels at lower than c in glass or water.

I think there's more to it than that. What about the Pauli Exclusion Principle? Don't the fermions in a BEC behave like bosons? That's a point - does the particles' spin change in a BEC?

I'm at a sort-of halfway house with BEC (as with a lot of other things). I've read and understand the low level stuff but I can't understand the mathematical treatments that explain it in depth. I wish there was a site that explained things in more depth but in idiot language (if that's possible).

I tell you as I've (perhaps) understood it: at "normal" densities and temperatures the wavefunctions describing the atoms don't "overlap" in a significant way and so different atoms can be considered as "independent" on each other; every atom is a single entity. At very high densities and very low temperatures (see also Heisenberg principle and tunnel effect) those wavefunction can overlap so much that single atoms become indistinguishable; at that moment a couple, or even a large number of atoms becomes an only quantum system, which total spin is the sum of its constituents spins, so an even number of atoms will have an integer spin and so will become a boson. Now many of these bosons can condense in a single quantum state, that is, a single macroscopic particle. Now you have exquisitely quantum properties in a macroscopic object, not in a single very little particle.

[DoctorBeaver (OP)]

Grazie, Alberto. I actually managed to understand that!

[yor_on]

I 'cut and pasted' this together before, just to try to remember myself how 'it' worked.
And now I share it with you:)

"
The Pauli exclusion principle is a quantum mechanical principle formulated by Wolfgang Pauli in 1925.
In contrast to bosons, which have Bose-Einstein statistics, only one fermion can occupy a quantum state at a given time.
Three types of particles from which ordinary matter is made—electrons, protons, and neutrons—are all subject to it.
In the Standard Model there are two types of elementary fermions: quarks and leptons.
In total, there are 24 different fermions; 6 quarks and 6 leptons, each with a corresponding antiparticle.

The Pauli exclusion principle helps explain a wide variety of physical phenomena.
One such consequence of the principle is the elaborate electron shell structure of atoms.
And of the way atoms share electron(s) - thus variety of chemical elements and of their combinations (chemistry).
An electrically neutral atom contains bound electrons equal in number to the protons in the nucleus.
Since electrons are fermions, the Pauli exclusion principle forbids them from occupying the same quantum state.
So electrons have to "pile on top of each other" within an atom.

Bosons are particles which obey Bose-Einstein statistics.
And in contrast to fermions which obey Fermi-Dirac statistics, they can occupy the same quantum state.
Thus, bosons with the same energy can occupy the same place in space.
Therefore bosons are often force carrier particles while fermions are usually associated with matter.
Although the distinction between the two concepts (Boson/Fermions) isn't clear cut in quantum physics.
The observed elementary bosons are all gauge bosons: photons, W and Z bosons and gluons.

A Bose–Einstein condensate (BEC) is a state of matter of bosons confined in an external potential and cooled to temperatures very near to absolute zero (0 K, −273.15 °C, or −459.67 °F). Under such conditions, a large fraction of the atoms collapse into the lowest quantum state of the external potential, at which point quantum effects become apparent on a macroscopic scale.

The result of the efforts of Bose and Einstein is the concept of a Bose gas, governed by the Bose–Einstein statistics.
Which describes the statistical distribution of identical particles with integer spin, now known as bosons.
Bosonic particles, which include the photon as well as atoms such as helium-4, are allowed to share quantum states with each other.
Einstein demonstrated that cooling bosonic atoms to a very low temperature would cause them to fall (or "condense") into the lowest accessible quantum state, resulting in a new form of matter. "

Taken from those three
http://en.wikipedia.org/wiki/Fermions
http://en.wikipedia.org/wiki/Boson
http://en.wikipedia.org/wiki/Bose-Einstein_condensate

and for a description of the phenomena of BEC fluids.
http://en.wikipedia.org/wiki/Bose-Einstein_condensate#Discovery

[DoctorBeaver (OP)]

yor-on - very helpful. Thank you.