At 03:29 PM 12/16/2012, Jed Rothwell wrote:
This kind of thing is such fun! See:
<http://www.popularmechanics.com/technology/engineering/news/110-predictions-for-the-next-110-years>http://www.popularmechanics.com/technology/engineering/news/110-predictions-for-the-next-110-years
I have a book from 1890 with predictions by people such as
Westinghouse for the year 1990. A lot of them were smack on target.
In some ways it is not so difficult to predict the future.
The latest issue of Sci. Am. is devoted to future predictions. Most
of the authors wimped out. They did not even take a stab at future
computers. One of them said that space-based cities would have to
have low pressure, which might affect the health of children. What a
nitwit! Does he really think we can build cities in space but we
can't develop materials strong enough to hold 1 atm of air pressure?
Well, the assumption that space colonies would have low ambient
pressure is unwarranted. I was, as I've mentioned, the administrator
of the L-5 society, back before 1980. The proposed colonies were
designed by scientists who would be able to consider strength of materials.
I can wonder how closely they looked at this, and perhaps some
mistake was made. The vision was of large spheres, with habitation on
the interior, living space would be at some level of effective
gravity (from rotation) and atmospheric pressure was assumed, as I recall.
The pressure would appear as a force against the interior of the
sphere, as a bursting force. If we think of the surface as formed
from panels held together, what would be the forces tending to
separate them? My intuition is that the forces would not be all that
large, compared to normal strength of materials; the huge collective
force generated by 1 atm over a large surface is *distributed* over
that surface.
Even if the analysis were accurate, a solution would be to divide up
the living space into modules, each one pressurised independently. We
certainly know that can be done!
(Jed, the problem is a 1 atm pressure over a large surface. If space
colonies are as envisioned, there would be a very large, empty
interior, not a vast array of columns and structures holding the
whole thing together. The writer's analysis seems wrong to me, but I
haven't seen it.)
