In article <4470@uswnvg.uswnvg.com> djwilli@uswnvg.com (Dan Williams) writes:
>:
>Shells also provide protection from gravity, and also from loss of precious
>water. Large variable tides would subject a variety of sealife to the rigours
>of a duo-environment.
In the real world, the race between the tortoise and the hare was won
by the hare. A shell limits movement and the rejection of waste heat
to the environment. Thus shelled creatures are less active foragers.
In the arms race between armor and speed, armor seems to have lost
most frequently. The large armored creatures are no more while the
agile endoskeletal creatures seem to have prospered. The design of the
largest armored amphibian, the turtle, seems to have been frozen early.
It has changed little in millions of years. I think rapid evolution is
necessary for intelligence to develop, and that a hard shell tends to
freeze evolution before it can advance enough.
>I would argue that Nature has worked with several successful bus designs in
>creating different species. Insects do walk on a double tripod base,
>I know of no three legged species but 5 limbs are common amoung some
>groups, {Elephants, and new world monkeys} How about snakes? Crustaceans,
>clams, or slug. The squid might be a good base design. Grow a shell to provide support, use large tentacles to pull the body along and retain the smaller
>tentacles as manipulators combined with the mandibles to provide leverage.
>Of course this creature requires either wheels under the shell, or a natural
>environment of a thick algal mat to ease the drag on its shell. :-)
I was suggesting that bipedal locomotion requires a more complex brain
than more stable bases. Whether one forces development of the other is
subject to debate. I suspect a feedback occurs. If we want to end up with
intelligence, we should prefer forms that encourage development of complex
brains. Neither 2 nor 4 limbs offer unconditional stability in motion
while the double tripod of the insect does.
>I would consider it to be a falacy to expect life to have evolved under rules
>simular to what guided life on this planet. Materials taken advantage of
>could be diferent, as could base structures. What if the intelligent creature
>is some form of communal organism.
I suspect carbon chemistry forces common structures for life. I don't
expect a creature to have titanium bones or Kevlar skin simply because
the creation of such things isn't compatible with the energetics of carbon
life chemistry. Life tends to fill every available niche, and the Earth
offers a very wide variety of niches, yet most creatures follow a common
pattern of material usage in their construction. I don't think this is
accidental. I suspect this is the only way the chemistry allows. Silicon
creatures breathing a fluorine atmosphere seem far fetched.
As to intelligent communal organisms, I suspect that inter-unit communications
would be too slow and too limited to make that work.
>: Thermodynamic considerations of surface/volume relationships would
>: seem to dictate that active complex creatures stay in a size range
>: similar to what we see about us. 6 inch tall intelligent aliens
>: seem unlikely, as do those much larger than the elephant.
>:
>Giants were not unknown in this world and given a little longer development
>time may have produced intelligent tool users. Our own species ranges from
>7 foot giants to under 3 feet tall. It might have been harder to survive
>outside that range, but we really don't have enough of a sample to say it
>is impossible to be intelligent tool users on either end of the scale.
I think we can be fairly confident of the lower bounds due to the
necessity for complex brains and the need to regulate temperature.
The top end is less clear. I'll concede that intelligent dinosaurs
may be a possibility. But I don't think they'd succeed in competition
with creatures in our size range. As I said above, life seems to actively
fill all possible niches, so it's highly likely that such competition
would exist. The thermodynamics favors the smaller creature when high
activity is required. I suspect that "monkey curiosity" is a prerequisite
for intelligence of high order to develop. A large sluggish creature wouldn't
be able to sustain that.
Gary
--
Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary
534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244 | |
------------------------------
Date: Wed, 19 May 1993 08:58:09 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Questions for KC-135 veterans
Newsgroups: sci.space
In article <1993May18.113849.15908@mksol.dseg.ti.com> mccall@mksol.dseg.ti.com (fred j mccall 575-3539) writes:
>
>Hmm. I would think being on edge would be *worse*, since that might
>make the tracks unsymmetrical around the spindle due to the sideways
>force on the head. Older drives used to tell you to reformat if you
>were going to stand the drive on edge; at 3+g, this side force might
>even be a problem for new drives.
Modern drives have embedded servo tracks. The G force on the heads from
a track to track seek are substantially greater than 3G. The servo can
cope. Head loading on the platter is another matter. It's regulated by
Bernoulli forces of trapped air flow. There's no servo to keep the spacing
constant. I don't know if 3G is enough to cause a head crash, but it might
be.
Gary
--
Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary
534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary
