The Secrets of Quantum Physics BBC4

[vinteuil]

I just don't know what the Copenhagen interpretation of quantum mechanics is.

... now you can find out :

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

Always happy to help...

[vinteuil]

I was so busy trying to work that out that I missed why the totals needed to less than 2 to prove Einstein was right and Bohr wrong- or was it the other way round - and why 2? .

.

Yes, RT, I struggled with those analogies too! And the four totals that JaK said came to >2 included one that was a negative figure I thought, so should have resulted in a total <2, i.e. Einstein and not Bohr was right!

... not sure whether this might help?

http://en.wikipedia.org/wiki/Bell%27s_inequality

[aka Calum Da Jazbo]

as i recall [a risky statement these days] the minus number was subtracted not added so that it was in fact added not subtracted so the total was >2 .... i'll get me gloves...

very much enjoyed the programme ... more please!

[french frank]

In the cards analogy, I didn't understand the possibility of both cards being the same colour. Was it significant? I understand that 'gloves' have two possible properties - left or right; and the coins are either heads or tails. So was that just to show that, in the case of a real pack of cards, anything can happen if there has been some 'rigging' of the test? And that was what Einstein thought?

[teamsaint]

In the cards analogy, I didn't understand the possibility of both cards being the same colour. Was it significant? I understand that 'gloves' have two possible properties - left or right; and the coins are either heads or tails. So was that just to show that, in the case of a real pack of cards, anything can happen if there has been some 'rigging' of the test? And that was what Einstein thought?

I think that the card game was to prove that, unless you conduct tests under very special circumstances, in this case deciding the rule after the event, you cannot be sure that the rule/situation/observation hasn't altered the outcome.

It would seem that the the physicists have either decided that observation does alter outcomes, or that they cannot prove that it doesn't.

Or have I missed all the points here completely?!

[french frank]

I think that the card game was to prove that, unless you conduct tests under very special circumstances, in this case deciding the rule after the event, you cannot be sure that the rule/situation/observation hasn't altered the outcome.

But wasn't the rule decided after the event - and there was still no random result, so it did seem to be supporting Boehr's theory (even though the colours were the same - so I assume that was not really relevant?).

[teamsaint]

But wasn't the rule decided after the event - and there was still no random result, so it did seem to be supporting Boehr's theory (even though the colours were the same - so I assume that was not really relevant?).

oh yes. I think I'll have to watch it again !! or next weeks episode.
( the thrust of the programme in any case ,as per those on screen quotes, was that Boehr was "right" wasn't it?)

Incidentally, the programme seemed to make rather less of the observation effect than other things I have seen, although clearly it did cover it.
here's Jim again.

https://www.youtube.com/watch?v=A9tKncAdlHQ

[french frank]

I shall certainly watch it again. I see Dr Graham Farmelo also contributed - author of the biography of Paul Dirac (The Strangest Man) which I must read again. At least the biographical bits were easy to understand :-)

[ardcarp]

It would seem that the the physicists have either decided that observation does alter outcomes, or that they cannot prove that it doesn't.

Or have I missed all the points here completely?!

That seems to be about it. Strange that if you're driving along the M5 you and all your fellow motorists are perceiving 3 lanes, tarmac, crash barriers, etc, but that they might all not be there during a quiet moment.

It's interesting that NASA relies entirely on good old fashioned Newtonian physics to get a satellite into an exact orbit around a tiny comet squillions of miles away...and it works.

I think I'm missing the point too.

[vinteuil]

That seems to be about it. Strange that if you're driving along the M5 you and all your fellow motorists are perceiving 3 lanes, tarmac, crash barriers, etc, but that they might all not be there during a quiet moment.


:

... and that, m' lud, concludes the case for the defence.

[Pabmusic]

Let me add something that is not strictly to do with quantum physics, but I think there's a connexion.

Everything we see, hear, feel, taste or touch is actually an illusion. Our brains receive information from all the stimuli receptors and our brains then make sense of it all (this is the 'information theory' point we talked of some months ago). So that our perception of reality is actually a model constructed by our brains making assumptions. We never (so it seems) visualise what we actually experience.

(I think the programme was great - can't wait till the next one.)

[ardcarp]

There once was a fellow from Deal
Who said that pain just isn't real.
When I sit on a pin
And it pierces my skin
I dislike what I fancy I feel.

[Pabmusic]

There once was a fellow from Deal
Who said that pain just isn't real.
When I sit on a pin
And it pierces my skin
I dislike what I fancy I feel.

[french frank]

About the gloves and the coins - don't they in fact prove Einstein right, not Boehr? I can't how the card analogy works.

If you have a coin, with a heads and tails, and split it down the middle, one half has the 'head-ness' and the other has the 'tails-ness'. If you spin the bit with the heads, it's bound to fall on its heads side because it doesn't have a tails - or it does, but that's on the other bit which which has a tails but not a heads. Spin both and they will fall, respectively, heads and tails. [The gloves have a 'right-ness' and 'left-ness'.] When the coin is 'whole' it could fall on either side but once it's separated it will fall on both sides when you spin it. Doesn't that make Einstein right?

Or have I missed the point too?

[Don Petter]

About the gloves and the coins - don't they in fact prove Einstein right, not Boehr? I can't how the card analogy works.

If you have a coin, with a heads and tails, and split it down the middle, one half has the 'head-ness' and the other has the 'tails-ness'. If you spin the bit with the heads, it's bound to fall on its heads side because it doesn't have a tails - or it does, but that's on the other bit which which has a tails but not a heads. Spin both and they will fall, respectively, heads and tails. [The gloves have a 'right-ness' and 'left-ness'.] When the coin is 'whole' it could fall on either side but once it's separated it will fall on both sides when you spin it. Doesn't that make Einstein right?

Or have I missed the point too?

My head's spinning ...