

Monster Pumps - mhb
http://www.overcomingbias.com/2015/09/monster-pumps.html

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TheLoneWolfling
Note that there are organisms that include "wheels" (Or rather, rotary motion
in general).

It's "just" that the only organisms on Earth that do so are microorganisms.
Look at flagella.

But there's nothing inherent about rotary motion that is impossible for
organics to do. It's "just" that there is no clear evolutionary path from
something that relies on linear actuation to something that relies on rotary
actuation.

(Also, note that there _are_ pumps that are continuous that don't rely on
rotary motion. Among other things, you can have two+ sacs, each with an inlet
and outlet valve that can contract and expand. One expands while the other
contracts, and vice versa. There's still some variation while the changeover
happens - but this can be avoided if you have >2 sacs. Alternatively, there
are peristaltic pumps that work continuously that can be implemented with only
linear actuators. (As a bonus, this means that you don't need a centralized
pump. You can integrate it into the blood vessels themselves.)

The bigger limitation tends to be respiratory, actually. Earth has only ~21%
oxygen currently. You bump that up (causing all sorts of other problems), you
can have faster and/or larger critters. Alternatively, you have more efficient
lungs (Note that human-style lungs are relatively inefficient. Ideally you
want air to flow in one direction through the lungs instead of alternating...
Birds do that, IIRC.) and/or more efficient oxygen / CO2 transport in the
blood. Red blood cells are not exactly efficient. (There was an Analog article
at one point about diamond spheres for artificial red blood cells. A related
article,
[https://www.foresight.org/Nanomedicine/Respirocytes3.html](https://www.foresight.org/Nanomedicine/Respirocytes3.html),
says the following "In the absence of respiration or atmospheric oxygen, a
fully-O2-charged augmentation dosage consisting of 9.54 x 10^14 respirocytes
could provide tissue oxygen delivery and carbon dioxide removal for 12 minutes
at peak exertion and 3.8 hours at rest even during cardiostasis" "A 1-liter
augmentation dose increases blood O2 storage capacity 18,000%")

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rcthompson
There's another example of biological rotary motion at the microscopic level
that is used by pretty much every living organism: ATP synthase[1].

[1]
[https://en.wikipedia.org/wiki/ATP_synthase](https://en.wikipedia.org/wiki/ATP_synthase)

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Animats
Life doesn't use full rotation much because life has no way to connect up the
rotating part to the circulatory and nervous systems.

But that's not the point of the article. He's talking about "em cities". What
he means are really big, perhaps planet sized, data centers running brain
simulations, at hardware densities near the limits of what physics permits.
This fantasy runs into cooling problems, so he's discussing that.

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VMG
That's the reason why I love his blog.

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msvan
> A goes as B to the power of C over D orders of magnitude.

As a non-native English speaker, am I correct in assuming the above to mean
this:

    
    
        A = B^C, A < 10^D
    

I've never heard this grammatical construction before, and the images are not
showing.

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monochromatic
Close; two minor details though.

1\. A = k*B^C. We can have an arbitrary constant k in there.

2\. 10^N > A > 10^(N+D). That is, A need not be small, it just has a
constrained range.

The "goes as" language is common, but a little loose/imprecise.

~~~
msvan
Thanks!

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digi_owl
I guess nature landed on the periodic pump action as it is basically a muscle
flexing.

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TheLoneWolfling
Look at birds. Bird lungs aren't actually continuously-pumping, but are a
relatively small step away from being so.

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digi_owl
This?

[http://www.peteducation.com/article.cfm?c=15+1829&aid=2721](http://www.peteducation.com/article.cfm?c=15+1829&aid=2721)

TIL that birds are natures four stroke engines...

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noobie
Chrome does not seem to support TIFF.

