Re: poly: ESS for HPLD

From: Hal Finney <>
Date: Mon Dec 08 1997 - 09:18:56 PST

Ted Kaehler, <>, writes:

> One has to ask the question, "What is the astronomical evidence that we
> are now looking out upon the ashes of one or more replicator sweeps that
> happened billions of years ago?"
> Is the 90% of the mass of the universe that is invisible actually the
> waste products of a replicator sweep? Is the missing mass inside the
> vast black volumes around which we see wisps of strings of galaxies?
> Is a too-large percentage of the mass of the universe in the element Iron,
> the final waste product of the fusion and fission chains?

BTW there are two different ways that "missing mass" is calculated.
One is based on gravitational effects within galaxies and galaxy clusters,
which require 5-10 times more matter than is visible. The other is
a cosmological desire to see the universe be closed and almost flat,
as predicted by inflation theories. This requires about 100 times more
matter than is visible. [Source: sci.physics FAQ]

It is an interesting thought that an earlier generation of replicators
burned through some currently unavailable energy source and produced the
dark matter. They neglected stars because either they didn't exist yet
or their output was too paltry to be concerned with.

As a more extreme view, consider that as the universe has expanded,
it has passed through various epochs. The earliest ones lasted only a
fraction of a second by our standards. There is a cool timeline chart
at the (somewhat awkward) URL:

We tend to think of the earlier epochs as being uniform and uninteresting,
just waiting for things to cool so that the important stuff could get
going (namely, ourselves and the universe we see). But maybe there was
more to it than this, and perhaps some of the earlier epochs could support
replication. It could even be the case that the activities of the
replicators produced structure which remained in later epochs.

(Also, there will be other epochs beyond our own, unimaginably cold
and barren by our standards, but which may seem quite warm and cozy to
replicators able to survive those conditions.)

> Alternatively, "What is the evidence that the universe is untouched, with
> energy sources and other things that have persisted for billions of years?
> Resources that any right-minded replicator would have consumed?"

Carl's reasoning emphasizes the behavior of replicators at the edges
of the sphere. If their whole point is speed, they might well ignore
resources which take more time to develop. I think Robin's equations
will show the same thing. You have to look behind the frontier though and
try to understand why there were no low-budget colonies left behind to
use the remaining resources. It's possible that there was too much of a
parameter-space gap to evolve from the fast-moving replicators to the
kind which could use stars and other low energy sources. In a sense,
we may be the first replicators able to utilize this source of energy.

Received on Mon Dec 8 17:54:19 1997

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