C[omp]ute

From: "andrew cooke" <andrew@...>

Date: Sat, 11 Aug 2007 09:09:32 -0400 (CLT)

from
http://ask.metafilter.com/69049/Why-Fund-Space-Exploration-Astronomy#1032708


physics has grown, over the last three centuries, from practically
nothing, to a beautiful, self-consistent, and almost-complete system. you
can think of it like a web of inter-tangled ideas. at the centre of that
web, which corresponds to our every-day experience, the interconnections
are amazingly thick, delicately interwoven, and pretty much
indestructible. whatever new comes along will not change that, just as it
remained constant through special and general relativity and quantum
mechanics.

out at the edges of the web, things are less constrained. there are tears,
errors, spaces for improvement. but these edges are far from our every-day
experience (the centre). they correspond to, for example, the
fantastically high temperatures and pressures that occur when stars
collapse. in conditions like that we believe that physics becomes simpler
- and that will lead to a unified model of physics.

but such a unified model will not change the practical, every-day use of
physics, because the only differences will, by necessity, be obvious at
those extreme conditions. in normal conditions, the new physics will give
the same answer as the old physics. it has to - the old physics works
perfectly in normal conditions. and this is exactly what we see with
special relativity (same results as newtonian physics at speeds much less
than the speed of light), general relativity (same results as newtonian
physics at energy densities much less that, say, a black hole), and
quantum mechanics (same results as newtonian physics at scales much larger
than an atom).

now "Connections" is largely a story of how the centre was built. it's a
cool program. but the centre is now built. it's done. finished.

if you watched a really cool program that explained how we came to
understand mathematics, would you argue that, because we finally came to
understand that 2+2=4, in the future we will continue making new
discoveries to show that 2+2=5? of course not. maths will continue to grow
in sophistication, but for everyday use, it's already complete. same with
physics.

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

that's history. i also mentioned the difference between physics and other
sciences.

physics describes the basic facts about the world we live in. it's the
broad sweep, not the fiddly details. when you get down to practicalities,
things can be horribly complex. other sciences are, largely, the
application of physics to complex systems.

it's not easy dealing with complex systems. you need to make
approximations - decide what is important and what can safely be ignored.
you need to find rules that apply "in general" and then see how far those
rules can go. this kind of work - on complex systems - gives us chemistry,
(modern) medicine, engineering, etc. all important fields that will
continue to grow and develop.

BUT. these are all based on physics. physics sets the ground rules.

so we are in a situation, now, where there are many things we don't know
how to do, in practice, with complex systems. but, at the same time, the
ground rules, the "laws of nature" are pretty much fixed.

it's as if physics defines the edges of the map, and then the other
sciences fill in the details.

so we already know that with "human scale" resources, travelling to
another galaxy will require a voyage that must last millions of years. no
amount of advances in chemistry, engineering or medicine can change that.
we don't yet know how it will happen (maybe medicine will find a way to
indefinitely suspend life, say), but we know the basic requirements.

enough about people's foolish ideas of space travel.

what i wanted to argue, finally, is that the sciences of the complex
(chemistry, medicine, engineering, etc) don't need any particular special
conditions to grow. you just need problems and money. and they tend to
give general results. that's why putting a man on the moon really wasn't
that hard - i don't mean to diminish the effort, but it simply applied the
then-current technology to the problem at hand. and current space
exploration (shuttle, space station) uses old technology.

so there's no need to push spaceflight to improve engineering -
engineering will improve anyway, because it's hugely important in so many
areas of our lives, and it has space to grow.

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

in case it's not obvious, i want to hammer home the conclusion: we gain
little of practical use from astronomy or space exploration. astronomy is
driven by a need to explore extreme conditions because that is where our
knowledge of physics is weak. as i have explained several times above, the
flip side of that is that the new physics will not be different from the
old physics for "every-day" practicalities. but at least astronomy has a
logical justification - those extreme conditions are only found "out
there"

space exploration, in contrast, doesn't even have a decent reason for
existing. there's nothing particularly special about most of the
engineering required (or the medicine, or chemistry). and even if there
were, today's space exploration isn't really pushing the boundaries
anyway.


ps. i forgot to say: i still have no argument with the approach that
astronomy deserves funding just as much as poetry. we should never forget
to invest in out souls.