The Secrets of Quantum Physics BBC4

[Gordon]

Different ways of illustrating the same ideas (nice to hear from Clauser and Aspect):

https://www.youtube.com/watch?v=STF0moww_zQ

Thanks for that - there are many more like it and I found this one particlularly good an explaining what JaK was doing!! As you say, good to hear it all from some of the Big Names of QM themselves.

https://www.youtube.com/watch?v=BFvJOZ51tmc

[ardcarp]

Yes thanks, ff. Once you get over the Wham Bam of the opening sequence, it explains things (as far as they can be explained) very clearly...especially having seen the Jim AlK programme twice through beforehand.

The only thing that puzzled me was the assertion that we would not have today's electronic gismos 'without Quantum Mechanics'. I assumed our digital computers were fairly earthbound, and indeed the programme did say that The Quantum Computer (that could instantly explore many possibilities at once) was in the future.

(BTW does anyone else have a family that thinks you're becoming a Quantum freak? )

[ardcarp]

I heard a nice quote on R4 at some stage today...

Any fool can think outside the box, but it takes a genius to invent a new box to think inside.

[Or words to that effect.]

[Richard Tarleton]

a Quantum freak? )

A Quantum Bohr, even?

And thank you Gordon for that great link. A glimmer of understanding! It's a funny thing, I was able to watch it straight through, following the arguments being set out by brilliant men sitting calmly in comfortable chairs. I don't know, television these days seems to impose a sort of hyperactivity on presenters. The only hyperactivity in this programme came from that bloke in the floppy bow tie giving the lecture near the end. No confusing analogies.

I liked Alan Aspect's observation at the end, that with quantum mechanics you could [I paraphrase] either just do equations, sticking to the mathematics, and be happy if they work, or you could look for analogies in the observable world around us, in which case there will always be something strange. Perhaps that was the problem with Jim's analogies, they just got in the way - but then television these days doesn't seem to like talking heads, there has to be something to look at.

[french frank]

And thank you Gordon for that great link. A glimmer of understanding! It's a funny thing, I was able to watch it straight through, following the arguments being set out by brilliant men sitting calmly in comfortable chairs. I don't know, television these days seems to impose a sort of hyperactivity on presenters. The only hyperactivity in this programme came from that bloke in the floppy bow tie giving the lecture near the end. No confusing analogies.

I wondered about that. Obviously there was an element of 'popularising' (not necessarily bad) in the BBC Four film, biut I wonder whether the audience actually slips through the gap of the 'simplified' version and the complexity of the subject. I found the YouTube versions more enlightening (and, as I said, I have NO physics at all and little maths).

[aeolium]

Thanks for that - there are many more like it and I found this one particlularly good an explaining what JaK was doing!! As you say, good to hear it all from some of the Big Names of QM themselves.

https://www.youtube.com/watch?v=BFvJOZ51tmc

Thanks for that wonderful link, Gordon (and your other very helpful posts on this subject). I found it much clearer to follow than JaK with his confusing analogies, though I'm a great admirer of JaK's programmes. It was interesting that near the end someone remarked about Bohr's belief in the value of ideas going back to the Buddha and Lao Tzu to try to understand the 'wholeness' or complementarity of things, and that earlier in the clip someone linked Bohr's ideas with those of Kant re the knowability of "the thing in itself". Perhaps a philosophical approach is needed as much as a scientific one in these complex matters.

[Serial_Apologist]

Thanks for that wonderful link, Gordon (and your other very helpful posts on this subject). I found it much clearer to follow than JaK with his confusing analogies, though I'm a great admirer of JaK's programmes. It was interesting that near the end someone remarked about Bohr's belief in the value of ideas going back to the Buddha and Lao Tzu to try to understand the 'wholeness' or complementarity of things, and that earlier in the clip someone linked Bohr's ideas with those of Kant re the knowability of "the thing in itself". Perhaps a philosophical approach is needed as much as a scientific one in these complex matters.

As I've mentioned on this forum before, the (for me) still great Alan Watts dealt with the analogies with Eastern spiritual traditions in several of his later works, particularly in "Psychotherapy East and West", which went several distances into this subject and beyond its own putative title as long ago as 1961.

[Gordon]

Thanks for that wonderful link, Gordon (and your other very helpful posts on this subject). I found it much clearer to follow than JaK with his confusing analogies, though I'm a great admirer of JaK's programmes. It was interesting that near the end someone remarked about Bohr's belief in the value of ideas going back to the Buddha and Lao Tzu to try to understand the 'wholeness' or complementarity of things, and that earlier in the clip someone linked Bohr's ideas with those of Kant re the knowability of "the thing in itself". Perhaps a philosophical approach is needed as much as a scientific one in these complex matters.

Quite so!! As Alain Aspect says, just do the maths and all is well - it "works" ie conformity with nature as seen through measurement and experiment - the famous adage "shut up and just compute!" - the philosophising belongs to a different scale and perhaps we should not trying to impose our scale on that of the particles. Einstein was more a philosopher which of course got him thinking towards relativity so we should not knock it. There is a balance between the formalism of maths on the one hand and the insights that come from thinking on the other [those gloves again] - complementarity?

From #92: The only thing that puzzled me was the assertion that we would not have today's electronic gismos 'without Quantum Mechanics'.

It's not just computers as Brian Green says [his book is very good BTW]. All goes back to understanding electrons in solids ie electrical conductors which then leads to SEMI-conductors that are the basis of transistors [invented in 1948 at Bell Labs in the US] and microchips that comprise billions of them. Also radio - aerials are means by which electrons rushing about in a carefully shaped conductor can cause the emission of a radio wave [photons with energies consistent with frequencies in the radio spectrum] - and vice versa, the wave captured at a receiver aerial and turned back into rushing electrons.

Strange things electrons in atoms - being negatively charged why don't they just fall into the positive proton as a result of electrical attraction? How do the electrons keep of each others' way in a cloud of charge aound the nucleus - is it just that they are mutually repulsive? A certain Pauli proposed an Exclusion Principle that appears to work that says no two electrons in the same system can occupy the same quantum state. How do they know that - do they communicate [imagine commuter type particles: "I say old chap, is that seat taken?]. Other particle types don't do that - why?

[JFLL]

Why 'the secrets of quantum physics', btw? I get the feeling that Secrets of ... , in the titles of TV programmes, now seems to refer to any subject not likely to be mentioned in a tabloid newspaper.

[Gordon]

Why 'the secrets of quantum physics', btw? I get the feeling that Secrets of ... , in the titles of TV programmes, now seems to refer to any subject not likely to be mentioned in a tabloid newspaper.

Yes, it's as if the behaviour in the sub-atomic world is some how reprehensible and that the programme will "dig the dirt" and expose some malpractice!

Headline: "Electrons to be prosecuted for non-disclosure of expenses!". Public inquiry.

Met Police officer to Electron: "Can you account for your movements between setting out for the House and getting there?" Electron: "Well, it's like this officer, it's a case of mistaken identity, it was my entangled partner and I have no idea where he is but of you find him you'll find he tells lies".

Headline: "Scandal of Electron's blaming absconded accomplice - police baffled".

BTW: anyone interesed in exploring some of the mathematics involved in QM could do worse that read this, it's quite well written:

http://www.amazon.co.uk/Quantum-Mechanics-The-Theoretical-Minimum/dp/024100344X

[ardcarp]

I am often the first to complain about trendy presentation and ditto presenters, but I have to say that in the case of Quantum physics, ordinary mortals like me need a load of analogies and visual props even to glean a smattering of the subject. And to be fair, Jim did stress that no analogy is a perfect representation. Looking forward to tonight's prog.

A Quantum Bohr, even?

Fermi la bouche.

[clive heath]

mmm.... Not sure about quantum effects relevant to normal radio transmission which I always understood to be Maxwellian Physics but am prepared to be corrected !" The band gaps in a metal's band structure are not important for low energy physics, since they are too far from the Fermi level."

[Gordon]

mmm.... Not sure about quantum effects relevant to normal radio transmission which I always understood to be Maxwellian Physics but am prepared to be corrected !" The band gaps in a metal's band structure are not important for low energy physics, since they are too far from the Fermi level."

Yes I wasn't being careful!! I didn't mean that aerials are quantum devices that behave strangely. QM enabled a better understanding of what happens to electrons in conductors, that's all, and I mentioned radio because it is still an electromagnetic phenomenon with photons as the associated "particle" - in this case the energy level in the photons is a lot less than light simply because of the large frequency difference. A photon is a "quantum" object but only interacts with matter in the QM sense when at high energy.

The "wave" is released from the transmitter aerial without electrons jumping bands but because of the accelerating charges of groups of loose electrons - charge - flowing in the aerial's metal conductors. A laser does produce an EM wave/photon flow by making electrons jump about but in a co-ordinated fashion so that the light is coherent.

[ardcarp]

...maybe the 'aether' needs to be reconsidered (even if it has been proved conclusively not to exist).

[clive heath]

One of the videos makes the point that the entangled photons ( in JA-K's experiment ) or electron substitutes in the Stern-Gerlacht version cannot be seen as independent objects and so almost by definition whatever the one turns out to be, the other is determined although not pre-determined. This is a tricky concept but no more so than the fact mentioned earlier that negative electrons do not fall into the attracting positive nucleus but exist in orbits defined by the very quantum ideas that were used to explain the emission spectra of hot metals.

One video used sheets of polaroid that I remember using in Physics classes. It occurred to me that you could entertain yourself with a laser pen and various domestic objects e.g. polaroid sun-glasses, sheer stockings etc. Watch this space.