[extropy-chat] Mangled Worlds

[Hal Finney]

Robin writes:
> (This article is about my latest physics paper.)
> http://www.newscientistspace.com/article/dn8766.html
>
> Is our universe about to be mangled?
> 17:43 23 February 2006
> NewScientist.com news service
> Maggie McKee

Congratulations on getting this publicity!  It is great to see.  I like
the way they describe you, "an economist who also studies physics."
It's amusing to see how they react to someone who does not fit into the
boundaries so well.

The mangled worlds idea is interesting but it's also kind of scary.
As I understand it, we get all of these worlds in the many-worlds
interpretation, but most of them have measure (ie amplitude) of
essentially zero.  We only experience the ones that have relatively high
measure, and this fact doesn't really have a good explanation in the MWI
(nor in conventional QM interpretations, but they don't aim so high).

The mangled worlds papers point out that when worlds split, it is not
completely clean.  There is still a tiny interference term.  Normally
that is so small that it is ignored.  But Robin observed that when we
are looking at worlds with very low amplitudes, the interference term
is actually relatively large, compared to those worlds.  This implies
that the physics of those low-amplitude worlds would be bizarre.
There could be macroscopic effects from other worlds.  Maybe quantum
phenomena would be visible at the macroscopic level.  Objects might
be in two places at once.  The laws of physics might appear to fail.
(These are my guesses about what could go wrong.)

Robin calls these "mangled worlds".  The assumption is that they are
uninhabitable due to this bizarre physics.  It follows then from the
anthropic principle that we can only experience non-mangled worlds, which
are (roughly) the ones where QM probabilities work out correctly, hence
we have an explanation for why we don't experience low-measure worlds.

The scary part is the possibility that the mangled worlds actually allow
a moment of existence before everyone in them is killed.  These mangled
worlds are forking off from the "main" branches at every instant.  By some
arguments, they are enormously more numerous than the main-branch worlds.
If so, it's very likely that our next instant of experience will be death
in a mangled world.  One would hope that these deaths are instantaneous.
But it's also possible that they are not, that there is a brief moment
of terror and pain as the universe shatters into insanity and people
are killed as the laws of physics themselves seem to go crazy.

Meanwhile the main branches carry on, oblivious.  The mangled worlds
would be like sparks thrown off from the main branches, brief but
far more numerous than the main branch worlds themselves.  The most
common experience for each individual, no matter how long he has lived,
would be sudden, violent death, repeated at every instant of his life,
an almost infinite number of times.

As I consider this possibility, I can almost see it, the universe breaking
into chaos around me.  Perhaps each time, the chaos emerges from a single
point where the quantum rules failed, bubbling out in some kind of violent
energy that I see sweeping towards me and then killing me.  It's possible
that this is real!  That this is the reality of the universe, a tiny
stream of normal physics surrounded by chaos and destruction.  If so then
my experiences, and those of everyone else, might be very much as I have
described.  A moment of shock and horror and then death, over and over.
It's a very frightening possibility.  God would have much to answer for
if he set up the universe like this on purpose.

Actually, I gather that it is not possible at this point to say much about
what life is like in the mangled worlds.  Is consciousness possible for
a period of time?  And what about locality?  How could a failed quantum
measurement elsewhere in the universe cause death to everyone else?
Perhaps with more study we will eventually be able to answer these
questions.

Hopefully it will turn out that the horror I have described is not real.
But it's also possible that things will turn out to work this way.  If so,
it might almost be worse to know about it, to constantly be living under
the knowledge that the most likely next instant of consciousness will be
the observation of a failure of physics that means death is at hand.
Instead of a moment of confusion, we would experience the terror
of knowing that the death we have feared our whole lives has finally
arrived.  And this will be the overwhelmingly most common experience of
our existence.

Hal