Re: a possible paradox

From: Matt King <>
Date: Wed, 29 Oct 2003 23:37:36 +0000

Hello Frederico,

    I've recently been taking part in a discussion on very similar lines
on the Fabric of Reality mailing list (yahoo groups).

Federico Marulli wrote:

>My reasoning is rather simple. Dealing with an infinite level 1
>multiuniverse, if an event, even an improbable one, doesn't violate any
>pshysical laws, it necessarly has to happen infinite times and in infinite
>different points of the space.
>So we can try to reason upon some examples which has a meaning from a
>physical point of view. For instance, we can think about the second
>principle of thermodynamics, according to which the entropy of a closed
>system necessarly has to increase. That means that, for instance, a gas
>put into a container of volume V will tend to spread by occupying all the
>available volume. This way we get the most possible disorder and the state
>is the most probable. Anyway the state in which all the gas is firmly in a
>v < V volume is not forbidden by thermodynamics; it is just a rather
>improbable state. But this event, having some chances to take place, has
>to happen in infinite places and times in our multiverse. So there will be
>infinite Hubble spheres in which everything happens exactly as in our own
>sphere, but in which any time you put a gas into a container, it will
>never occupy the whole volume. At the same time, there will be infinite
>spheres in which some day the gas will occupy all the volume and some
>others not. And so on.
Yes, this is predicted to happen (in very rare universes) in the Many
Worlds Interpretation (MWI). It's also predicted to happen under the
Copenhagen Interpretation (CI), you'd just have to wait a very long time
to expect to see such a violation of the 2nd law of thermodynamics.


> From all these examples we should deduce that, if all the infinite
>observers we have considered took advantage of the same approach we have,
>they would obtain very different interpretations. So the model seems to
>admit in itself the chance of being wrong. It is consistent with its
>foundamental hypotheses the fact that it is inconsistent. So here we have
>the paradox. But shall we put into discussion our experimental method just
>because some unlucky observers are not in the condition to understand the
>universe and the way it works?
> To answer this question I have tried to go even further with my
>reflection. I believe we have no reason to think of being privileged
>observers just because we observe the universe moving according to our
>physical laws. Moreover, physics has been formunlated just starting from
>our observations, so it is clear that our models come out to be consistent
>with them. If these observations were not like that, we would discard
>them. But the same thing would be valid for all the other infinite
>observers and any of them could think of being privileged. Besides, from
>one day to another, we could also realize that all our models are no
>longer valid. What would happen if we lived in an Hubble sphere in which,
>by chance, entropy began to lower all of a sudden?
We can call these universes where strange things that seem forbidden by
our statistical laws of physics (which are not fundamental) happen
regularly through shear chance 'magical'. I believe your question could
be rewritten, is there any evidence that we are not living in such a
'magical' universe ourselves?

You are quite right that any particular physical law you could construct
*could* be the result of observing quantum statistics which have been
skewed in one way or another. For instance, you could be in a 'magical'
universe where gases don't expand in line with the predictions of our
statistical mechanics/thermodynamics. Instead, you would draw up your
own set of laws to describe this behaviour, assuming that the deviations
happen in a systematic way. Or you could be in another 'magical'
universe where even fundamental particles obey totally different
equations of motion, as a result of skewed sampling on every microscopic
observation of the wavefunctions concerned.

In order to formulate these laws, the deviations would have to be
systematic. Universes admitting such 'magical' laws would be very much
rarer than those where the deviations do not permit systematic modelling
to occur.

The evidence that we are not in such a 'magical' universe is this.
Though our laws describing the behaviour of gases etc. were originally
derived from observations of large amounts of gases - macroscopic
investigation - we have since found that they are 100% bconsistent with
our observations of single particles of gas - microscopic investigation.

In 'magical' universes, we would not expect this consistency.
Observations of large amounts of gas would not be consistent with
measurements made on individual particles in the vast majority of these
universes. The fact that these two sets of laws of physics are
consistent indicates that we are not in a 'magical' universe with very
high confidence - because if we were in a 'magical' universe we would be
far more likely to have inconsistent macroscopic and microscopic physics.

I should point out that there does remain a vanishingly small
possibility that we could be in one of the extremely 'magical' universes
where both macroscopic and microscopic laws of physics are skewed in a
mutually consistent way, however given the tiny probability of this
being the case I think it is quite safe to ignore it.

Hope this helps,



When God plays dice with the Universe, He throws every number at once...

Received on Wed Oct 29 2003 - 18:39:14 PST

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