Philosophy Now Forum

Hi Folks,

I have a little problem with the above. Here's the situation as I understand it.

We only know probabilities of outcomes of quantum events. This is not a failing of ours but a feature of the natural world. It is all we will ever know.
If we arange an experiment such that the outcome is two particals one with up spin and the other is down spin ( perfectly feasable ), then if we dislocate the fist partical from the second ( in theory many hundreds of light years. Then when we measure the the spin of the first we know the spin of the second. The assertion is that the particles in the experiment only make their mind up which state they are in upon being measured. Thus the dislocated particle assumes it's spin as a result of a distant measurement potentially violating the information speed limit of light.

I have no problem with all of the above except what evidence do we have to support the decission being made only at the time of measurement?

All experimental evidence suggests that this is the case. Every Bell test experiment has been interpreted as favouring pure quantum theory over Einstein's realist explanation.

Hello Rortabend.

Thanks, but what experiments, what is the bell test to which you refer?
I can't concieve of a test that will show that the decision is only made when you make the measurement. What principle must be employed?


Regards

Hi folks,
Glad this came up because I'd like some understanding.
What is the proposed experiment? That we can have a particle that can exist in either one spin state or the other? We can then separate the spin states into two particles that we can send a long, long, long way away? The assumption is what? That they are still one particle in the sense that if you alter the spin state of one the other must change(and why this assumption)? And if so then there must be a faster than light transfer of information? How could we prove this without a means to violate the 'speed of light' in the first place?
a_uk

Hi Rortabend,
Whats Einstein's realist explanation? Whats 'pure quantum theory', that the world is made of discrete particles?
a_uk

Does empty space have an existence independent of the matter within it? Einstein said no. In his universe, there can be no space without matter. Quantum physicists, to my understanding, say that the "uncertainty principle" allows for spontaneous, though fleeting, creation and destruction of fundamental particles from empty space. So, is empty space really "empty" at all? Or, is it an ocean seething with creation and destruction of subatomic particles?
First make a definition of Existence. For something to exist it has to be observed... something has to know it is there (I go to a deeper definition that a particle could know another's existence). This paradox could in itself clear up you question because the very fact you ask is something there, you put something there; but maybe you would call that semantics.
Einstein never believed in quantum mechanics as it has been proved. He believed there was "hidden variables" that we cannot find, but exist all the same (just because we don't see it; doesn't mean it isn't there). Maybe you would say this agrees totally with my previous statement: it does not. There are subtle differences in the math that allow one to define existence through measurement (some call it statistical approach, but that too deviates at some deeper mathematical level). The essential difference being that Einstein believed there was an underlying mechanism that gave rise to the statistics, even if we couldn't observe this mechanism. That is all I will say for the moment on measurement and existence.
Another approach is the quantum cosmologist's approach. Take the universe as a whole and make it homogeneous (apart from any large bodies such as planets and stars). Then we will find that on average there is a temperature of 2.9 Kelvin throughout space; the remnants of the big bang (the universe has slowly cooled as it has expanded from the time it came to existence [existence comes in again; I think this is a very important word to define; without anthropomorphism]) Matter is a funny thing when it get to small scales; it is not as we would know it, something 'hard'... we prefer to talk about energy; this is the view you expressed above - things popping into and out of existence through the uncertainty principle.
There is the question of length scales in the previous statement. This is very important. If we bring together the two ideas of measurement, and looking at a certain length scale (to find if something is there or not there we need to know how to 'look' at it),.. you could even talk about quarks, or strings, or even superstrings if you want,.. it makes no difference. The question you need to ask yourself is how small can this "space" you talk of be? If you talk of Planets and stars and gravity,.. then you can, quite rightly, talk of independent space in between them (I give this as a thought example and not one to pick at with the subtleties of gravitational interaction),... if you talk of fundamental particles such as electrons and alike, you cannot talk of empty space,... maybe there is a smaller scale in which you can again talk of empty space,... it all depends on the interaction of observation we are talking about: Neutrinos are very had to detect,.. and hence, you can probably talk of a lot of empty space when looking at it from a neutrino's point of view. Maybe when we get to the length scale of superstrings.. everything is so jumbled up that there is just a big mess of existence everywhere.
Another small point is that we are talking about a local measurement to find if space is empty. It is not good to work in spatial dimensions; it is not wrong; but it will lead to complications when trying to really understand quantum interactions (you will be left with the idea that things pop into and out of existence and you will end up with metaphysical paradoxes).

RachelAnn,

Please don't take this the wrong way but you are the fith post on this thread and you have monumentally change the subject. I had hoped to engage on a simple succinct problem i have myself. I would be delighted to correspond with you over some of the MANY question you pose later when i have more time. I am a littel frustrated and feel your many questions warranted it's own thread and is possibly a distraction from my pointed question.

Regards

Got it - understood!!

hi Diomedes71,

Diomedes71 wrote:...We only know probabilities of outcomes of quantum events. This is not a failing of ours but a feature of the natural world. It is all we will ever know.

I always think this description understates in some way what it describes, i.e. we know things about Matter to 99.999999999999% probability(is twelve about right?), I'll take that bet against there being a spaghetti noodle monster anyday(although, no offense your noodleness, you know how these meat-based products think.)
a_uk

Hi Folks

All experimental evidence suggests that this is the case. Every Bell test experiment has been interpreted as favouring pure quantum theory over Einstein's realist explanation.

I'm waiting on Rortabend, it seems he has something to contribute ( or she ) .... not likely .....

x

RachelAnn wrote

Does empty space have an existence independent of the matter within it? Einstein said no

Consensus would seem to indicate yes. If i understand u correctly.

So, is empty space really "empty" at all? Or, is it an ocean seething with creation and destruction of subatomic particles?

Yes it's a sea particles having momentary existence before recombining with there antiparticle. Again this is consensus opinion and it explains why blackholes aren't black and actually slowly evaporate(very).

So, is empty space really "empty" at all? Or, is it an ocean seething with creation and destruction of subatomic particles?

I'm alone right now ..do i exist?

He believed there was "hidden variables"

I also favour some kind of hidden variable interpretation of Q.M. There are several equally valid interpretations of Q.M. one of which is Hidden variable interpretation, it was sunk for a while but i reasantly heard it had life back in it. The standard interpretation which provokes all the hooraaa! is called the Copenhagen interpretation and it is the one which questions alot of our assumptions about reality.. aka.. 2 slit exp, spooky stuff, Schrodingers cats.. etc.
Actually those are facts but the Copenhagen interpretation is most shaking to our reality. It essentially accepts full implications of uncertain events and all it's consequences

Matter is a funny thing when it get to small scales; it is not as we would know it, something 'hard'...

YES YES YES YES YES .. you do have a deep understanding of things. The late great Richard Feynman couldn't have put it better. Though he did put it well. My take - Do you really think things are made of ping pong balls?

maybe there is a smaller scale in which you can again talk of empty space,...

Forgeting the popping in and out of existence bit - space is real - it is the fabric upon which we have our show. It eminated from the Big Bang every bit as much as the stuff of stars. It is it which is expanding and reddening distant galaxy light.

you will be left with the idea that things pop into and out of existence and you will end up with metaphysical paradoxes).

Theory has it that things do pop in and out of existence. What is the paradox?

phew.....

Hi Rortabend,
Whats Einstein's realist explanation? Whats 'pure quantum theory', that the world is made of discrete particles?

Einstein's realist explanation of quantum entanglement is that there are hidden variables which explain why when we measure one particle, the other has to have a different value. In other words, the act of measuring one particle doesn't determine the value of the other, it's just that we unbeknownst to us there are variables that mean they have to have these values. The 'pure' quantum explanation I referred to is that of the Copenhagen interpretation which allows action at a distance. So when we measure one particle it really does determine the value of the other particle, no matter how far away it is. This violates the principles of classical mechanics which is what Einstein was worried about, hence the hidden variables (realist) explanation.

Thanks, but what experiments, what is the bell test to which you refer?

Bell tests are attempts to decide between hidden variable explanations of entanglement (Einstein's realism) and the 'pure' quantum explanation (Copenhagen interpretation). As I said before, all of these experiments are thought to favour the 'pure' quantum explanation. Hence, despite what Einstein said, the quantum world is not the world of classical mechanics.

Rortabend (He)

Rortabend,

OH MY GOD, GOD DOES PLAY DICE !

thanks for the pointer to the bell experiments. Just read wiki's take about bell inequalities and the EPR paradox.

I don't know what this means for me, for a long time I have strongly believed in the hidden variables ideas. But as Richard Feynman said if your theory disagrees with observation of nature.... Your theory is wrong.!

Regards.

I don't think that EPR and quantum mechnics generally tells us anything - it's totally the wrong approach. Why look for the smallest thing? It's like some religiously inspired superlativism that goes unquestioned.

And why be suprised that the cause and effect relations operating on the classical level don't apply? As I've often said - it's pointless applying the logical principles of the existing universe to explain the origin of the universe. Cause and effect do not apply because time, space, energy and matter - and therefore the possibility of cause and effect, came into existence in that moment.

I think there's a similar thing going on here. We apply the concepts of the classical scale universe to explain the quantum, and end up with a probabilistic understanding - whereas, I'm inclined to think that applying our conceptual framework is simply nonesensical.

Are we able to look beyond our conceptual framework? Only insofar as we can accept the universe doesn't have a cause. I say it, but find it intellectually unsatisfying, and impossible to reconcile with that which I can know - that which is explained by the conceptual framework of the existing universe.

The project, to reconcile quantum and classical, I think is misconcieved. The scientific project should be improvement of our understanding of the relations of classical scale reality, and applying that to provide for human and environmental welfare.

Hi Mark

Why look for the smallest thing?

Simply because it is in our nature to be curious about the world around us. In any bigger sense you might as well ask - Why get out of bed?

I understand and agree that the quantum world is difficult to reconcile with the macro scale and in it's self I have no problem with it. But I am curious to ask why is it so difficult to reconcile the differences, even though that is not the central theme of my poser here.

Critically the EPR tells us that physical reality is not determined until the measurement is made and that any counter part reliant on it's properties consistency will assume the corect properties no matter how far away the counter part to the experiment is.

Regards