On 8/4/22 13:16, Jonathan Clark - jonathan at att.net (via tml list) wrote:
> Alex Goodwin wrote:
>
>> Jonathan, let's see how far down that rabbit hole I can go.
>
> Pretty far, obviously. Well done! :-)
Thanks for your reply, and thanks again for knocking stuff loose.
> <snip>
>
> https://www.quora.com/How-much-land-is-there-on-earth has Prof
> Mohammad Gani saying:
>
>     In nicely rounded numbers, the earth has about 14,900 million
> hectares (100
>     hectares make 1 sq. kilometer) of land, out of which roughly 5000
> million
>     hectares is good to grow food, But at the best current technology,
> 10 billion
>     people can be fed adequately from just 200 million hectares (less
> than 2% of
>     the available land).
>
>     Broadly, the earth has 75 times more land than we need. You can be
> more than
>     certain that we can never rationally use any more than 10% of the
> land, even
>     with absolute wasteful misuse.
>
> So there you go. Note that the 'what sort of life is this anyway?'
> question is not
> addressed by the professor in this post.

I'm not sure I'm competent to answer that "what sort of life" question. 
I might be able to use Prof Gani's figures later on.

If we turn up the numbers a little, to an _ecumenopolis_ at Macau
densities (21,600 yammerheads/sq km, over 90% of the planet's sq km -
not just land - the precise how-to-do is a mere implementation detail at
this abstraction level), you get 10 trillion yammerheads on Terra
(actually, 10.006 trillion, but I rounded off).

Loading everyone up into 16 km skyrakers (assumed 5,000 stories average,
compared to an assumed average of contemporary Macau of 50 stories)
packs 10 trillion (10x 1E12) yammerheads into 0.9% of Terra's surface
area - approx 3% of its land area.  Your urban heat island effects would
be doozies.

Conversely, a 5,000 storey Terran ecumenopolis gets you to 1 quadrillion
yammerheads (1x 1E15) - I _think_ that would be population code F in the
UWP.

And this completely ignores any orbital infrastructure.

For cross-media comparison:

Asimov's Trantor only peaked out at 40 billion people, yet was
explicitly an ecumenopolis - either the planet was significantly smaller
than Terra, Isaac didn't carry his numbers through, or some combo.

The Terran ecumenopolis I mentioned above would still only be a pale
shadow of Coruscant/Imperial Centre, where you easily could have a
100-trillion-strong (first-order, at least) _elite_.

Going over to TravMap, we have Yaskoyloyt (Datsatl 1602) with 1 trillion
human inhabitants and 7/8 Terra's diameter.  Per its writeup on
https://wiki.travellerrpg.com/Yaskoyloyt_(world) , "Yaskoyloyt is not a
single world-wide city" - ie, it's not an ecumenopolis.

>
>> If you start packing people into sky_rakers_ (punching up through the
>> planetary boundary layer, so at least 1600m tall on Terra, IIRC - all
>> your BASE jump are belong to us), increase those figures by at least 1
>> order of magnitude, probably more.
>
> Yes, I agree. Building higher than that might be tricky - you have to
> get into
> pressurized buildings, to keep the oxygen levels up, but at
> Traveller-level TLs
> that's do-able. Or you build *down*, which goes along with heat-pumps,
> but then
> the waste heat gets vented into the atmosphere, which is going to lead
> to other
> problems.

<AiryWave>Details, details... </AiryWave>

There would be a lot nicked from station construction for such
buildings, as highports have to worry about pressure as it is.

As for the waste heat, not if you vent it high enough - top of
troposphere should do the trick (assuming the top of the skyrakers
aren't higher).  Something like http://vortexengine.ca/ , which pumps
the waste heat to be dumped into controlled, anchored, artificial cyclones.

> <snip>
> You are very welcome. Thank you for the thoughtful response.
>
> Jonathan

Hopefully that's a worthy follow-up.

Alex