Liquid Helium II the superfluid (part 6 Second sound)

[bazanv12]

They found out over 50 years ago, and I found out just 20 minutes ago.. I wonder what other thigs I don't know...

[johny260]

how much heat can you put in it?

[KellerDude4]

Imagine sticking your tongue on that container. You'd be pretty sorry.

[kowalityjesus]

damnit this is what americans should be concerned with.

[TheCryptore]

why doesn't the glass become sueprfluid too?

[Zantorc]

@TheCryptore Superfluidity in solids is only a theoretical possibility and would require temperatures many oders of magnitude smaller. In addition glass would not have the necessary quantum mechanical properties to become superfluid. Superfluidity is due to the atoms forming a Bose-Einstein condensate, which has only been observed in helium and clusters of a few thousand rubidium atoms.

[TheCryptore]

@Zantorc oh thank u! so only gasses can become superfuild? so no solid state can reach the superfluid?

[Zantorc]

@TheCryptore Not necessarily. Superfluidity in anything other than liquid helium requires cooling below 0.000001 degree K. A 'supersolid' is solid but at the same time superfluid. There is some evidence to suggest that the cooled rubidium atoms are crystaline and therefore supersolid. A supersolid may have been seen for the first time in 2004 in helium crystals - it's still the subject of debate. Macroscopic quantum phenomena like this are not just weird, but weirder than you can imagine.

[Zantorc]

@Zantorc Continued... When it comes to supersolids the jury is still out, but the evidence is mounting that they exist. In such a supersolid atoms in the superfluid state would lose individual identity. They would behave as a single entity. Each superfluid atom would be at the same position as every other superfluid atom.

[m9kuhn]

@Zantorc which would mean that the atoms themselves are not moving on the molecular and they have reached absolute zero right?

[Zantorc]

@m9kuhn Not sure I understand your question. The atoms in a superfluid or supersolid would all be in the ground state. But the ground state doesn't have zero energy. As you lower the temperature more atoms go into the ground state. Because they are in the same state it is impossible to distinguish them. We are not used to think about objects being in more than one place at the same time but that is literally what happens and it gives rise to all these phenomena.

[m9kuhn]

@Zantorc what i ment was at absolute zero do the electrons stop moving around the protons as if they were frozen as well, which would make a super solid

[Zantorc]

@m9kuhn No even at a basic level that would violate quantum mechanics. As you localise the position of an electron to a smaller and smaller space you must increase its momentum (and therefore velocity), from the Heisenberg uncertainty principle.

[TheCryptore]

@Zantorc WOW hey can I have ur contac such skype or msn I would really like to learn more about this! if u want!

[KristenZych]

4:00 dramatic pan

[mwdub02]

the guy said it is ""reversible in the thermodynamic sense""..........then at the end he said'" irreversible"". he has confused me...cause it cannot be both rev and irrev.

[Zantorc]

@mwdub02 Regard He II below the lambda point as composed of 2 fluids:

1)A superfluid fluid with perfect flow reversible in the thermodynamic sense.

2)A normal fluid with irreversible flow.

Just below the lambda point most of the liquid is composed of normal fluid at absolute zero it would consist of only superfluid. The ratio depends on only temperature and it's a dynamic equilibrium (think of an atom sometimes belonging to the superfluid and later the normal fluid - not as being fixed forever).

[Zantorc]

...cont When it flows out of the beaker with the porous bottom, its only the superfluid which flows out. But the normal fluid left behind is still below the lambda point so it must adjust its ratio to be partly superfluid (which then immediately flows out). When the temperature is very low it flows out more rapidly because most of the liquid wants to be in the superfluid state.

[AlemitoFilms]

I thought supercunductivity was one of the strangest things that could be observed by naked eye, now I've changed my mind! Great explenation!

[Zantorc]

@AlemitoFilms Superconductivity and superfluidity are closely related - they're both Bose-Einstein condensates. In a sense superconductivity can be regarded as superfluidity for electron pairs

[povilas84]

This is best educational video I have seen so far. Its quite detailed and yet very entertaining. Thanks a lot for putting it here.

[blakespower]

this is what they should be teaching in public schools. Not crap about Rocks and Global warming

[SPINNICUS]

Brilliant

[ndeplume08]

Truly fantastic! If only all scientific discovery and explanation was made this clear and understandable.

[solaris10user]

What a fantastic video series !

[ale86itn]

Thanks to all of you.

[Zantorc]

Shouldn't we be thanking you? As you can see I cleaned the audio and video slightly (and got the synchronisation right). If you'd like a copy let me know.

[ale86itn]

My thanks to you for your message. I would be happy to have a copy - but not now. My computer whiz grandson Brett (bmatulis) is now helping U.S. students at Diving & Oceanography at South Caicos.He wiil eventually get in touch with you, Sir. -..As regards myself, I am a half blind computer dummy.Best regards.

[LizzyAston]

this was amazing bruv

[artrasa]

Very interesting videos, great presentations.

[raachaell]

fantastic :D