From: Hal Finney (hal@finney.org)
Date: Mon Jan 06 2003 - 11:57:47 MST
In another thread the question arose as to whether existence is
better than non-existence, particularly for living, conscious beings.
Superficially the answer is obviously yes. Certainly most of us look
very unfavorably upon the prospect of ceasing to exist, and presumably
we are happy to have experienced existence rather than not to have had
that chance.
However there are some important philosophical arguments that suggest
that this reasoning is misguided, that existence is a much broader and
more complicated category than we naively suppose. What does it mean for
something to exist? Could there be forms of existence beyond the physical
objects around us that we can see and touch? Are there worlds beyond
the reach of our senses where other forms of existence are possible?
One of the more plausible extensions to "reality" is the many worlds
interpretation (MWI) of quantum mechanics. This model, which has
gained increasing credibility among physicists in the past couple of
decades, supposes that there are parallel universes where things have
happened differently. Any time there is a quantum measurement event,
which is uncountably many times every second, the universe in effect
splits into parts where the measurement result happens differently.
These separate worlds are all equally real, but we are only able to
perceive one among myriads.
>From this perspective, the question of existence vs non-existence becomes
more difficult because there is so much wider scope for existence.
It is hard to say which beings are non-existent, or whether in fact
non-existence is even possible. We need to drop the boolean distinction
between existence and non-existence and instead use a continuous
measurement of the probability or "measure" of the existence of a
particular entity. Arguably more measure is better, for that entity.
This step forces us to take at least a more nuanced perspective towards
these questions.
An even broader answer to the question of reality goes back to Plato, who
claimed that the only true existence was for mathematical and geometric
entities. Perfect circles, squares and cubes have a primary existence,
of which our physical world offers only a crude shadow or approximation.
In modern times this idea has been generalized to the concept that a wide
range of mathematical objects have Platonic existence, independent of
our thoughts or perceptions, existence outside of our universe. We gain
a connection to the existence of our physical world by postulating that
our minds and in fact the entire universe are just mathematical objects
of great complexity. So instead of the universe holding minds which
create mathematics, we have mathematics on the outside, of which a subset
is universes including our own, and minds inside of those universes.
In other variants there may be "bare" minds that are mathematical objects
of their own which perhaps fantasize universes around them.
Outlandish as this idea may seem, a number of modern thinkers are
pursuing it. See Hans Moravec's article at
http://www.frc.ri.cmu.edu/~hpm/project.archive/general.articles/1998/SimConEx.98.html.
Physicist "Mad" Max Tegmark (who had an article on the MWI in a recent
issue of Scientific American) presents his version of the idea at
http://www.hep.upenn.edu/~max/toe.html. This page is worth looking at
as it shows a chart of all kinds of different mathematical structures
with an eye towards the kinds of complexity that an abstract mathematical
object would have to have in order to host self-aware subsystems (i.e.
living, conscious beings).
Another variant is by Juergen Schmidhuber,
http://www.idsia.ch/~juergen/everything/html.html, where he proposes
that all computer programs exist and are being run. This amounts to
much the same thing, since we can (more or less) associate computer
programs with mathematical objects. Wei Dai has created a mailing list,
the "everything-list", to discuss the theory that "everything exists",
and Schmidhuber continues to contribute occasionally.
Why would someone believe a crazy idea like this? I can suggest a
couple of possibilities. First, the MWI already forces us to seriously
consider the possibility of other universes. I think most "everythingers"
do accept the MWI and are ready to look beyond it. Second, there is a
certain simplicity to the notion. As Schmidhuber writes in his abstract
above, "Is the universe computable? If so, it may be much cheaper in
terms of information requirements to compute all computable universes
instead of just ours." There is actually less information needed to
specify all universes than for just a particular one.
Another reason has to do with the anthropic principle. At the Tegmark
page above he shows a diagram illustrating how carefully selected
the physical parameters of our universe have to be in order to allow
for life like ours to exist. A tiny difference one way or the other
and we would not be here. How can we explain this? One answer is to
point to a creator, such as God, who has carefully selected and tuned
the parameters to allow for life to evolve. But if we want to stick to
naturalistic explanations, another possibility is to suggest that all the
universes exist, each with its own set of parameters, and then life will
only evolve in those universes where that is possible. It seems that
you need some foundation of multiple universes like this to invoke the
anthropic principle, otherwise it doesn't really have explanatory value.
To sum up, the theory that everything exists cuts through a number of
classic philosophical problems. It explains why our universe exists
(because everything does) and why it has the properties necessary
to support life (because of the anthropic principle). It even allows
for the possibility that the total information content of the entire
universe of existence is zero, which is certainly not the case if only
our personal universe exists, and that is attractive philosophically
as well, and perhaps even gives the notion a certain self-bootstrapping
flavor.
And to close the circle, if everything exists it doesn't make sense to ask
whether existence is better than non-existence, because there is no such
thing as non-existence. It may still be possible to do as in the case
of the MWI and define a "measure" function over the entities that exist,
and then to work in terms of probabilities for these entities, in terms
of what fraction of the "multiverse" they occupy. We can say that having
more measure is better than having less, and that our actions can (in a
sense) influence the measure of ourselves and the entities around us.
So there is still a foundation for actions and decisions, for taking
steps to affect the multiverse in terms of what is important to us.
Hal
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