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WHAT IF THE SUN WENT OUT


	Disasters are in fashion these days, and  somehow I have been
led to think about  a really big one - what if the sun went out?  The
first question to ask before  writing our tale of panic and  paranoia
is this.  How many people could survive how long?

	Not many and not long is  the obvious answer, and we envisage
the  scene in the  movie a  last survivors in  the underground bunker
shiver and draw lots as  to who will be eaten next and  secretly plot
to fix the lottery.

	Unfortunately  for you fans  of disaster movies,  the obvious
answer is  mistaken.    The  more  one  thinks  about  it,  the  more
possibilities for survival come  to mind, and my final  conclusion is
that most Americans would die of old age, and their descendants would
survive almost as long as they would without the disaster - for a few
billion years.  I  have not so far been able to find  a way for India
to survive as well.

	The  first problem that comes to mind  is that it would begin
to  get cold.    How  cold  and  how  soon.   During  the  winter  in
Antarctica, it  is dark all the  time, but it takes months  to get to
-100F even at the pole.  At  the coast, it doesn't get anywhere  near
that cold because of the sea.  The facts seem to be as follows:

	The thermal time constant  of the atmosphere is a  few weeks.
However,  the time constant of  the ocean is many  years.  Because of
convection in the  ocean, the  surface can't freeze  until the  whole
ocean  reaches 4  degrees  Celsius.   Because  of  convection in  the
atmosphere,  the atmosphere  can't get  much below freezing  near the
coasts or much  below Antarctic temperatures  inland until the  ocean
surface  freezes.     Therefore,  we  will  have   very  cold  winter
temperatures near  the  coasts and  had  better evacuate  the  inland
areas.

	We will be unable to heat our  houses, because we already use
40% of our  energy for that purpose, and we couldn't even get through
one year with our available  energy production.  Therefore, we  would
start dying off in  a few months, right.  Wrong,  we just wouldn't be
able  to afford so much  housing.  In fact, we  would have to abandon
90% of our  housing and live  in the remaining  10% and insulate  the
walls of that 10% by  piling up dirt.  At barracks levels of crowding
and good insulation, we could get by on body heat if we  could
find the food to generate the body heat.

	However, if insulation is too good, it is necessary to provide
specifically for ventilation, and simply pumping in fresh air loses
the heat content of the air that is pumped out.  Therefore, it is
necessary to use heat exchangers that warm the incoming fresh air
with the heat of the outgoing stale air.  These are in commercial use
in Europe and could be manufactured quickly.

	The next big problem is food.
How long would the  initial supplies last, and what would  we do when
they ran out?  Since most crops are annual, we normally have a
substantial fraction of a year's supplies of most foods.  Some foods
are in surplus and larger supplies are on hand.  We have larger
supplies just after a harvest than just before.  We would stop
feeding cattle to make our grain last longer, and we would ration
food severely.  Probably this would give us two or three years to
get a new food supply.

	There are several long range possibilities, but the main
short range one is petroleum.  We presently produce about
500 million tons of petroleum per year, and processes are in use
for feeding it to bacteria that produce proteins that are used
for animal food supplements.  These processes would have to be
used on a very much larger scale.  It would be more pleasant to
feed the bacterial products to chickens and eat the chickens, but
quite likely we would have to eat the bacterial products ourselves
for a few years.

	The 500 million tons of petroleum would produce more than
enough food for 200 million people.  A person eats about three
pounds per day, but three quarters of its content is water, so
one can estimate that our population would use only about
160 million tons per year of the petroleum.  Our ten year's reserves
would then stretch to thirty years.

	The most critical problem may be the freezing of the
atmosphere.  How long this would take is hard to calculate,
because it depends on the exchange of heat between the oceans
and the atmosphere.  The easy calculation is that the ocean
can supply several hundred times the amount of heat in currently
in the atmosphere before the surface freezes.  This would
probably give us a breathable atmosphere for about ten years.

	After that the oxygen we need to breathe will still be
around, but it will have to be vaporized to be used.  It will
therefore be better to recirculate what we use in our buildings,
and this mainly means separating out the carbon dioxide from
the atmosphere and splitting it into oxygen for breathing and
carbon for food.

	This separation and splitting is now performed by
green plants with the aid of sunlight.  This is a possibility,
but it would require enormous underground rooms and an
enormous amount artificial light used at an efficiency of
around one percent.