X-Message-Number: 11212
Date: Tue, 02 Feb 1999 00:05:41 -0700
From: Mike Perry <>
Subject: Tipler, ETs

Thomas Donaldson, #11200, writes
>
>This is a second reply to Cryonet 11174-11178, basically to Mike Perry's
>discussion of cosmology, in which he brings up Tipler's ideas again.
>
>The problem is that on current data Tipler's cosmology looks less and less
>likely. Sure, anything is possible, but Tipler's version does not now
>seem likely. 
>
>So why are you still bringing up his book? Because you think he's said 
>things that make his cosmology irrelevant to his main thesis? Because you
>think that our present likely universe will still show the same
>properties? Or do you have other reasons? I'd really like to know.
>
All right. NOT because his cosmology is still relevant. I think it's pretty
well shot down by recent discoveries (which are very exciting to me, I
might add). But Tipler is still a superbly trained, theoretical physicist, and
much of what he says is still valid, such as (I think) the idea about persons
and processes being essentially finite state machines. (This claim, though,
could perhaps be more strongly maintained using such ideas as Lloyd's
universal quantum simulator.) That's why I brought up Tipler and his book.

On the subject of ETs and why we don't see them (the Fermi paradox), it's
certainly a fascinating question. I don't think the possibility is ruled out
that they are out there but have their reasons for not wanting to contact
us, despite being basically benevolent and wanting to help, but I lean toward
the idea that we are alone. There is an extended discussion of this in
my book--here is an excerpt dealing with why intelligent life might be an
unlikely occurrence.

"... there could be steps in the evolutionary process that were much
"luckier" than we think.

"There are several stages in earthly evolution that raise still-unanswered
questions as to the likelihood that they would happen over the span of time
and conditions involved. In this we are assuming an earthlike environment,
with a convenient source of steady illumination nearby, etc. These steps
include (a) the transition from non-life to life itself, (b) the development
of photosynthesis, (c) the appearance of the more advanced, eukaryotic cell,
(d) the advance from single-celled to multicellular organisms, (e) the
emergence of sentience or consciousness, and (f) the emergence of
human-level intelligence from nonhuman sentience. Most of these steps,
according to the evidence, happened only once, and all were necessary for
intelligent humans to emerge.

"As one case in point, most life forms other than bacteria, including all
animals and plants, are composed primarily of nucleated or eukaryotic cells.
Each such cell is an enormously complex mechanism, containing a smaller
structure, the nucleus, a "cell within the cell," and an intricate array of
organelles and other structures. By a complicated procedure the entire
assemblage is able to reproduce itself-the cell divides into two cells
which, by ingesting material, grow into nearly exact replicas of the
original. In contrast, a bacterium is a smaller, simpler, prokaryotic cell,
lacking a nucleus or the other complex structures of the eukaryotic cell.
From traces in the fossil record it appears that life forms were prokaryotic
for several billion years until, relatively recently, the far more complex
eukaryotic form emerged by a process that is largely unknown, and possibly
very unlikely.

"The occurrence of even one highly unlikely step could be enough to make the
occurrence of intelligent life unlikely to happen more than once in a
universe such as ours. Or several steps together could form a prohibitive
barrier.

"An additional possibility is that the entire evolutionary sequence is not
that unlikely, given the surrounding conditions, but those conditions
themselves are very rare. The sun must have burned very steadily for
billions of years, while the earth maintained a nearly constant orbit. The
planet Jupiter seems also to have been important in deflecting many
asteroidal objects that otherwise could have struck Earth, creating
conditions intolerable for life. Occasional objects that did get through,
however, may also have been crucial to the evolutionary process, as in the
impact, approximately 65 million years ago, that appears to have killed the
dinosaurs and opened the way for mammals to develop.

"In 1996 some dramatic findings were announced that seemed to have a bearing
on the likelihood of life evolving: Traces of ancient life, it was said,
were seen in rocks from Mars. The rocks themselves had been blasted away
from the Red Planet by a meteorite impact some 16 million years before. By
chance their wanderings in space placed them, a few thousand years ago, on a
collision course with Earth; they crashed in Antarctica. Painstaking
analysis of the meteorite fragments, discovered in the 1980s, established
the likely Martian origin and also, that the rocks were actually several
billion years old. Moreover, they contained traces of what some claimed were
biological remains, including tiny, rod-shaped "fossils."

"This sparked a spirited controversy, but in the end, the case for life
looked doubtful. If the remains are truly biological, however, it still
would not resolve the question of whether this life evolved independently.
Mars is close enough to Earth, after all, that material from one planet
could find its way to the other, as presumably happened with these rocks. It
is possible that life originally evolved on Mars-when it had a more
favorable climate than today-and was blasted to Earth where it proceeded to
take root and create the earthly biosphere. Or alternatively, some ancient
earthly cataclysm could have seeded Mars with the beginnings of life. Again,
we don't know the answer, nor can we yet rule out the possibility that life
is rare and unlikely to evolve even when conditions are favorable."

Mike Perry

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