

Quantum Suicide - sabhishek
http://science.howstuffworks.com/quantum-suicide.htm/printable

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mxh
Does the Copenhagen Interpretation strike anyone else as eerily like lazy
evaluation?

My other thought is that once you're doing 'thought experiments', you've
become rather unmoored from science as I understand it: Observation,
Hypothesis, Prediction, Experiment, and so forth. Hopefully, the 'thought
experiments' will lead to something testable.

~~~
rms
Thought experiments can reveal profound results beyond what current
instruments are capable of measuring.

In 1935, Einstein and friends published a thought experiment that basically
said "Well if all this quantum theory is true, then locality can't possibly be
a principle." It turns out that locality isn't actually a principle of physics
and now we have entanglement, Einstein's "spooky action at a distance."

~~~
mxh
To the extent that thought experiments suggest real experiments, they are
indeed valuable. I disagree that they can 'reveal ... results', however. For
instance, Einstein's thought experiment was designed to 'prove' that QM was
wrong. Obviously, that result was incorrect.

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joeguilmette
haha quantum physics may as well be chinese to me. the only explanation that
has _ever_ made the least bit of sense is that cartoon with the old man super
hero talking about light particles.

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majimojo
Nice movie plot for Jet Li perhaps, but they don't actually explain how to
kill yourself in all universes. So, unless you're a cat or Solid Snake, you
can get out of that box now.

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curi
They have no clue what they are talking about. For example this:

 _This is the same case with quantum suicide. When the man pulls the trigger,
there are two possible outcomes: the gun either fires or it doesn't. In this
case, the man either lives or he dies. Each time the trigger is pulled, the
universe splits to accommodate each possible outcome_

Universes do not split like that. That would mean many universes were being
created from nothing every instant. What actually happens is there are
_already_ infinitely many "universes" and they _become different_. And not one
per outcome, but in proportion to the probability of outcomes.

~~~
angryprofessor
>Universes do not split like that. That would mean many universes were being
created from nothing every instant. What actually happens is there are already
infinitely many "universes" and they become different. And not one per
outcome, but in proportion to the probability of outcomes.

It's not the writers of the article who have no clue. It's quantum physicists
themselves.

In the Copenhagen interpretation of QM, a conscious observer induces wave
collapse (a random process). In this interpretation, there are no other
worlds. In Wave Collapse/Many Worlds, a parallel universe is created in which
wave collapse occured but gave a different outcome.

There are different interpretations of QM (e.g. bohmian mechanics or
GRW/stochastic collapse) which don't have this problem. If you are interested
in QM, I strongly suggest looking these theories up. But Copenhagen QM (the
theory in most textbooks) does have this problem.

The reporter did an adequate job of explaining the consensus view. The problem
is really that the consensus view can allow for nonsense such as what was
described in the article.

~~~
curi
_In Wave Collapse/Many Worlds, a parallel universe is created in which wave
collapse occured but gave a different outcome._

That is incorrect. Many Worlds does not say universes are created all the
time, it says they already exist and become differentiated.

BTW all the other interpretations are ridiculous attempts to avoid facing
counter-intuitive facts. See, for example, David Deutsch's speech at the
recent Everett conference
[http://www.philosophy.ox.ac.uk/misc/everett/Deutsch%20-%20Ap...](http://www.philosophy.ox.ac.uk/misc/everett/Deutsch%20-%20Apart.wmv)

~~~
hugh
<i>That is incorrect. Many Worlds does not say universes are created all the
time, it says they already exist and become differentiated.</i>

Actually there's no real consensus on that point, even among many-worlds
theorists. Some folks suggest that universes "split", others suggest that they
"become differentiated", and a third set of folks say that they do something
which isn't really properly described by either of the above options. Deutsch
has one of the more widely publicised many-worlds interpretations, but it's
not the only one out there, and it's not necessarily the most widely accepted.

~~~
curi
I don't really care what views are popular, (though MWI is popular among top
experts to whom it matters), I care which views are true. So what matters to
me is which proponents say things that _make sense_ and give good explanations
and arguments. Deutsch does, including a powerful and concise argument in
chapter 2 of his book. When someone gives a reasonable counter argument then I
will reconsider, but that has not happened.

And, of course, Deutsch isn't the only example of the MWI side making more
sense. Here is another source:

<http://www.hedweb.com/manworld.htm>

Edit: If you can give a non-ridiculous summary of any other interpretation, go
ahead...

~~~
angryprofessor
Some of the many worlds variants make sense. I prefer bohmian mechanics (I can
reason about it better), but I have no objection to MW. Ultimately I don't
care one way or the other: the predictions for MY universe are the same,
whether or not it is unique or one amoung many.

However, the point I was making is that most physicists believe in wave
collapse. The writer of the article was simply providing a reasonably good
summary of QM with wave collapse. According to Q1 of your article, this is
still a mainstream belief except amoung string theorists, apparently. I agree,
it's almost certainly wrong. But that's not yet a mainstream position.

As for other non-ridiculous interpretations, just look at bohmian mechanics or
GRW. Bohmian mechanics postulates that particles exist and are guided by the
wave function. The testable physical predictions are identical to many worlds.
GRW makes different physical predictions (possibly testable in the near
future), but the theory makes sense as well.

~~~
curi
There are two varieties of bohm interpretation:

one says that there are "hidden variables". what this means is all particles
store information, from the start of existence, about all other particles they
will ever have anything to do with. how they store this vast amount of
information isn't explained. then, they act on the information. then somehow
either this information is used by some physical process to follow the SE
(Schrodinger Equation), or they don't bother with that and say the SE is
sometimes false for some reason or other. notice all the parts where some
explanation is left out. that makes it ridiculous to call this a reasonable
alternative to MWI. MWI does flesh out details.

the other version -- the pilot wave theory -- says there are special particles
that go along one groove of the wave function: our universe. this is a
ridiculous attempt to make up some special status for our universe.

GRW is about the wave function randomly collapsing when there's enough
information flow we might have to face the prospect of other universe-sized-
things. why random? b/c that's better than saying "when we want it to so we
can avoid MWI" and better than copenhagen's "when people are watching". how do
they try to get away with this? well, mostly universes don't affect each
other. so basically any time a universe isn't going to affect ours anymore, a
"random" collapse occurs, and it disappears. this doesn't break things too too
badly b/c ... it's a bit like saying anything so far away we can't see it,
doesn't exist. frustrating to disprove. but still ridiculous.

