Re: Article: How Will the Universe End?

From: Mitchell Porter (
Date: Mon Mar 08 2004 - 05:47:55 MST

Tommy McCabe said

>Second of all, the material in the brain isn't "protoplasm"- the supposed
>existence of such material, which was thought to give life to beings, was
>disproven centuries ago.

When people speak of "protoplasm" today, they just
mean living matter. It's not an assertion of vitalism.
With words like "cytoplasm" and "nucleoplasm" still
perfectly current among biologists, I find it hard to
object to the admittedly old-fashioned "protoplasm".

>Third of all, this completely ignores any kind of ultratechnology or even a
>Singularity happening. Fourth, the Singularity could prevent, or at least
>postpone, the universe winding up in such a state.

Well, these points boil down to, "The physical and
cosmological theories behind these predictions could
be wrong." All these scenarios involve positing that
the laws of nature are a certain way, from the beginning
to the end of time, and GIVEN SUCH ASSUMPTIONS,
you can calculate constraints that will remain true no
matter how ultra your technology is. The "light-heartedness"
of the cosmic eschatologists probably comes from
the knowledge that many of the assumptions behind
these extrapolations are rather arbitrary. We are at a
point in cosmological model-building where we know
how to get the model to do just about anything -
expand faster and faster forever, go from accelerating
expansion to decelerating expansion and then to collapse,
bounce after collapse - but it all depends on having the
right recipe of fundamental fields, and we only have
low-energy information about what sort of fields there
actually are.

>Fifth, there is no communication mechanism specified. Interstellar dust
>doesn't have an electric or magnetic charge.

How do you draw that conclusion? Ions can exist in
interstellar space, just like anywhere else.

>Sixth, unless some form of FTL travel is assumed, the entity would take
>trillions of years to think a thought.

Who cares? It has forever!

>Seventh, the particles would have to know exactly where the other particles
>were in order to relay signals (at least to relay signals efficiently-
>omnidirectional transmissions waste huge amounts of energy). Eighth, even
>given a workaround to seven, the particles are likely to be moving and so
>would have to keep constant track of each other (sounds like a lot for a
>little bit of dust!).

This *is* something I'd like to hear more about.
There are no rigid bodies in these dust clouds
(apart from the dust grains themselves) - where
is the structure? What are the functional components
(receivers, processors, transmitters; damage detectors,
repair mechanisms)?

>Ninth, although we of course don't fully understand the brain, it isn't
>true the we have "no idea" how it works. Just ask a neurologist.

I think he's talking about consciousness (the "hard
problem", why it feels like something to be a brain,
etc.), not cognition.

>Tenth, this organism would still consume quite a lot of energy, and no
>energy source is given. Eleventh, given the time frame (10^36 years in the
>future), and given current theories about cosmic expansion, who says there
>would even be dust?

Expansion isn't relevant to whether there's dust.
If the universe starts with galaxies of dust and expands
forever, the dust will still be there. The expansion of
the universe (at least, the non-accelerating sort that
is understood) only takes place in intergalactic space,
where the cosmological "Friedmann geometry" dominates.
Inside the gravitational well of an individual galaxy, there's
no such expansion. So, if galaxies were indefinitely stable
objects, the long-term future of the universe's geometry
would consist of galactic gravitational wells of constant
size, dimpling the homogeneous curve of smoothly
expanding intergalactic space, and increasingly remote
from each other. If the fate of galaxies is to end up
as galactic-mass black holes which then Hawking-evaporate,
then the ex-galaxies will constantly be losing energy
in the form of Hawking radiation, and the gravitational
dimples on the expanding universe will shrink to nothing,
replaced by a gas of radiation too tenuous to ever
re-condense into a new generation of localized objects.
If there's proton decay, a fatal leakage of galactic mass
into intergalactic space might even occur long before
black hole evaporation becomes relevant.

You should read Dyson's paper, "Life Without End".

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