At 12:56 PM 27/10/00 -0700, Jason wrote:
>What I find sort of puzzling is the concept that somehow the variables
>required for reality have the capacity to be selected for. Scientists say:
>"Well, if this fundamental number was even -slightly- different, life never
>would have come into being! How extraordinarily unlikely!" as if the
>variable in question were being spit out by a mystical random number
>generator somewhere-- as if it had the opportunity to be many different
>numbers and by pure chance settled on this one.
I'm more bothered by suggestions that the number generator is
systematically biased in a way that gives rise to darwinnowing. I like the
idea, but I don't know of any physcial rationale for it. Here's a bit from
THE LAST MORTAL GENERATION that addresses this issue. Mitch Porter once
offered a comment on this point but it eluded me:
================
Physicist Lee Smolin has suggested that black holes extrude out of our
universe and expand as Bangs into new universes, re-mixing the laws of
nature a tad each time, a line of thought similar to Hawking's. Smolin's
story involves infinities of time, cosmos following cosmos, universes
giving birth to baby universes that Bang and expand and fade into
attenuated living death or perhaps are crushed into fiery nothing - but not
before giving birth to billions of new baby spacetimes of their own.
The core idea stems from the mathematical discovery, crucial to quantum
theory, that the vacuum - emptiness - is unstable and liable to emit
energetic particles. What's more, the briefer this catastrophe, the
greater the available energy. At high enough energies, this flaw in
emptiness can buckle inward to form a black hole, which may then inflate
wildly to form an entire segregated cosmos. Depending on the interaction
laws coded into that cosmos, it might recollapse in a tiny fraction of a
second, bubble with micro-black holes that collapse in turn, or even blow
out into a fresh spacetime universe akin to our own.
Imagine, then, a fabulous series of popping bubbles in the void. Most
vanish with no progeny. Some persist long enough for their colossal
outpouring of energy to form elemental vibrating strings and membranes, and
for those to coalesce into quarks and electrons, and then into hydrogen and
helium atoms. If the values describing the new universe are suitable, its
contents may form stars that cook new, heavier elements in their compressed
gasses. Some of these, rich in carbon and other key elements, will explode
in thermonuclear glory, their cores crushed down to black holes, their hot
debris seeding the skies with the raw materials of life and new stars.
In a few universes, Smolin speculates, an extraordinary set of values will
coincide, yielding two interesting features: a maximum number of stars
suitable for making black holes (and hence new universes with slightly
variant parameters) and many other stars and their planets suitable for
evolving life, and even intelligence. The key step in this somewhat
Darwinian argument is that the parameters determining the shape of the new
cosmos must resemble those of its parent, rather than being picked at
random. Granted this, after a while most universes in the mega-cosmos will
cluster around certain apparently arbitrary values - the kind that produce
observers like us.
By re-mixing the fundamental parameters a tad each time, eventually (by a
process more akin to Gerald Edelman's `neural darwinism' than to genuine
Darwinism, in which phenotypes compete in the same environment for air
time) certain kinds of fecund universes will dominate. As a
side-consequence, it might be that these kinds are hospitable to life.
Suppose a set of laws congenial to the manufacture of abundant black holes
will birth more universes just like mother. Barren ensembles of laws will
die out. After a while, most of the universes in superspace will be
fertile. Smolin believes ours is just that kind. Intriguingly, most black
holes are made when very large stars explode as supernovae, which also
happen to build the elements of life out of the simpler elements originally
forming those stars. So it's a side-effect of universes that make oodles
of black holes that they need to hang about long enough for such stars to
form, to explode, to seed the cosmic dust with the making of life, which
will then evolve and start wondering about the meaning of life. And the
beauty of Smolin's suggestion is that it's testable. It moves out of the
domain of faith and into that of science.
A more extreme possibility is that once life arises by chance and thrives,
it will thereafter manipulate the parameters in one or more of the baby
universes such that life-supportive universes (perhaps available for
colonisation via wormholes) become prevalent. This wild notion has been
explored by cosmologist Edward Hamilton in the sombre pages of the
Quarterly Journal of the Royal Astronomical Society.
I am attracted to Smolin's view of a Darwinian metauniverse replete with
`gosh numbers' - as Frederik Pohl calls the relevant `dimensionless' values
which describe reality's architecture - selected by the fecundity of their
local bubbles. However, he not only gives no mechanism for mutating the
fundamental values, he provides no hint of why they should be constrained.
Neither of the Darwinian prerequisites for natural selection are present.
There's no reason to suppose that systematic and heritable variations would
occur between bangs (rather than none at all or, more plausibly, wildly
divergent ones), and there's no competition for resources. You can start
a baby universe just by goosing an infinitesimal wormhole. Cosmic
inflation does the rest. Pure science! Pure magic!
Recall the logic of organic evolution. Suppose that the earth had been an
infinite flat plain, or plane, in which various regions were connected by
hyperspatial wormholes. Then the original pre-DNA self-bootstrapping
critter might have spread through the ooze forever, chomping and mutating
and dividing as it went. But there'd be no concerted contest to drive
evolution, so everything (it seems to me) might stay pretty much at slime
level, unless complexity theory and such controversial factors kick in and
smarten things up eventually. Smolin's story gives no mechanism for
mutating the fundamental values, nor does it provide a hint of why they
should be constrained. Stars allegedly evolve `to make best use,' as
science writer John Gribbin summarises the theory, `of the available
materials'. But there is no coding transmitted between stellar generations
and no memory substrate to mutate - just a shift in the population of raw
elements from previous supernovae generations.
Watching galactic spiral arms, Gribbin has suggested, it is obvious you're
seeing a living system. By this reasoning, the water vortex I saw tonight
in my bath was also alive, poor little thing. `Many universes,' he claims,
`are competing with one another for the right to exist'. But the
mathematics of this story tell us the universes are orthogonal, at
right-angles to each other, so to speak. So it is difficult to see how
they can `compete'. And for what resource?
==================================
Damien Broderick
This archive was generated by hypermail 2b30 : Mon May 28 2001 - 09:50:18 MDT