[extropy-chat] Singularity heat waste

[BillK]

On 7/17/06, Robert Bradbury wrote:
<snip>
>
> Rather than focus on simply cell temperature, I would also want to draw
> attention to cell volume.  Out of all of the possible volumes that
> Eukaryotic cells could have why is the general structure for Eukaryotic
> cells to have ~1000x the volume of Prokaryotic cells?  There are a few
> examples of multi-genome copy 'fused' cells (some muscle cells, some liver
> cells, megakaryocytes & granulocytes) but these are relatively rare compared
> with the number of total cell types (~300) and species (thousands [mammals]
> to millions [insects]).  If you start to fiddle with the cell temperature --
> why not fiddle with the overall architecture?
>
> One has to wonder why there is a lack of imagination going on with both
> nature (same ole same ole) and virtual realities?  Where are the Sci Fi
> novels or Video Games where the players are constructed out of utility fog
> for example?
>

It's not nature's lack of imagination.
It is the classic surface area to volume ratio problem.
As you probably well know, :) Prokaryotic cells (bacteria) are the
more primitive cells and Eukaryotic cells are believed to have evolved
from groups of prokaryotic cells. So naturally eukaryotic cells have
to be bigger to accommodate all the functions.


<http://www.brooklyn.cuny.edu/bc/ahp/LAD/C5/C5_ProbSize.html>

Quote:
Gases and food molecules dissolved in water must be absorbed and waste
products must be eliminated. For most cells, this passage of all
materials in and out of the cell must occur through the plasma
membrane (see diagram above).

Each internal region of the cell has to be served by part of the cell
surface. As a cell grows bigger, its internal volume enlarges and the
cell membrane expands. Unfortunately, the volume increases more
rapidly than does the surface area, and so the relative amount of
surface area available to pass materials to a unit volume of the cell
steadily decreases.

Finally, at some point, there is just enough surface available to
service all the interior; if it is to survive, the cell must stop
growing.

The important point is that the surface area to the volume ratio gets
smaller as the cell gets larger.

Thus, if the cell grows beyond a certain limit, not enough material
will be able to cross the membrane fast enough to accommodate the
increased cellular volume. When this happens, the cell must divide
into smaller cells with favorable surface area/volume ratios, or cease
to function.

That is why cells are so small.

--------------------------------------------------------------

Sounds reasonable to me.
M brains must face a similar type of problem, scaled up of course.

BillK