Gonzalo asked:

David Bohm as I understand is an advocate of the Copenhagen school of quantum physics
interpretation. He mentioned that he found himself surprised when Jiddu Krishnamurti stated, in on of
his books, that the observer is the observed. Now, Bohm says that in quantum physics he has
witnessed this phenomena. Could you please explain how this (the observer is the observed) might
translate into quantum physics and how this ties in with Krishnamurti's statement? Also, in Lee
Smolin's book The Life of the Cosmoshe says that in order to understand Quantum Physics and
Relativity one needs to appreciate the influence of Leibniz, Gottfried Wilhelm on them in this regard.
Could you please tell me how he influenced the way we look at science today?

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This whole area is a very controversial one, so keep in mind that any definite answer I give you will be
agreed with by some and disputed by others. That being said, first, the Copenhagen school may have
been Bohm's early position but I do not think it was his later one. That school was a very cautious one
in interpreting QM, and basically took a very positivist attitude. That is, Bohr was very careful never to
commit himself to definite statements going beyond the observed results of experiments: electrons,
photons, wave-functions, etc., were what was observed in the lab, and the rest was speculation. But
one problem was with the phenomenon of instantaneous action at a distance, that is, when
"entangled" particles become disentangled; another related problem was with the phenomenon of
decoherence, the collapse of the wave-function. The Copenhagen school was content (by and large)
to note the events. Bohm wanted to explain them, and in doing so, he conceived a brilliant theory
which accounts for action at a distance, at the price of hypothesizing a kind of carrier wave for it,
which has never been observed. No one really knows what to do with this theory; it works but it
effectively violates Occam's Razor. As far as I know it's pretty much ignored today.

The stuff about Krishnamurti relates to the phenomenon of decoherence. When a coherent system is
observed, it collapses from an indefinite state which is the superposition of a number of possible
states, into one state. So everyone for a long time was asking just what "observation" was, and many
people (including Bohm) felt that since observation requires an observer, that implied that mind or
consciousness was intimately bound up with the universe, forcing it, in effect, to become definite.
Well, zowie, right? The death-knell of that idea happened quite recently, actually, when people started
fooling around with quantum computing, and noticed that when they tried to build computers that
needed superposed states to calculate, they went and decohered all by themselves... annoying, you
went out for a cup of tea and wanted to come back to find some huge problem solved and the thing
had just collapsed on its own, no observer necessary. Ugh. Well, it turned out that a physicist (among
others) named Mulhauser ("The End of a Quantum Romance") had predicted that decoherence didn't
really require an observer, just anysort of interaction from the outside onto the coherent state, and it
would go poof. So much for mind as integral to the universe, Krishnamurti, etc., we're back to the old
uncaring physical world. Now the above might be how (and I haven't read that particular book) Smolin
was referring to Leibniz (aside from the fact that he invented calculus independently of and
simultaneously with Newton). Leibniz' monads were a kind of mental substance supposedly
underlying matter. But as I say, that viewpoint is now outdated.

Actually, as I understand it, the contemporary picture of decoherence is more complex. Consider that
any state is a wave-function, then the question becomes not only why a wave-function collapses, but
why most wave-functions collapse into one(or a few) rather more definite wave-functions. What's
special about the state we normally look around and see, and call the real world, which is, after all,
just one set of wave-functions that is selected by that collapse? Why that set? I don't know the
answer to that, offhand, but I think that it has to do with just settling on the state with maximum
probability... but that's just speculation on my part. Then we might ask, why collapse at all? I don't
know the answer to that either. However, there have been some extremely interesting experiments,
very recently, in which it turns out that there is a fine structure to the wave-function well beyond what
people thought was possible, which may indicate some kind of dynamic events there that we're just
beginning to understand. Perhaps collapse has to do with interference effects and what we call the
stable state is a kind of interference pattern. All speculation on my part, don't get excited; I'm probably
wrong. Anyway, that's my viewpoint, in an extremely small nutshell, but you'll still find lots of
wrangling about what it all means and how consciousness fits into it all.

Steven Ravett Brown

I could only answer the question about Leibnitz, and then I am speculating somewhat as I haven't
read Smolin. I can see two possible influences. Firstly, Leibnitz invented (co-invented with Newton?)
the calculus. Probably more important, though, was Leibnitz's Principle of Sufficient Cause, which QM
seems to violate, but which also seems to be a necessary presupposition of science. It says (from
memory) that every event has a cause sufficient to explain it. Some quantum events don't. Yet it is
hard to see what science is, if it is not the search for the (generalised) causes of all events.

Tim Sprod