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DO diamonds really
last for ever, as the title of the James Bond story suggests?
Until very recently the surprising answer was “no”; nothing was
going to last for ever. No object, be it planet, star, galaxy or
diamond necklace would survive when the atoms that comprised them
disintegrated.
This theory of “proton decay” posed no immediate
threat. No disintegration of matter will be complete in less than
1030 years, a 1 followed by 30 noughts or a million
trillion trillion. But the theory was none the less depressing.
Huge though this number is, it is the merest snap
of the fingers compared with eternity, the timespan promised by
the continued existence of time and space in the open universe.
The theory therefore suggested that for all of
eternity (after the trifling future period of 1030
years), the universe would be absolutely empty. There would be no
possibility of life, matter - or even light. It would be a cosmos
of nothingness. There seemed to be no chance that a divine being
might exist, for what deity would wish to rule over a dead
universe? I became an atheist at once on hearing of it.
But happily for those of religious - or at least
agnostic - inclination, the theory of proton decay seems to be
wrong. All the experiments designed to test it have so far found
nothing.
The biggest of these is an artificial lake
containing 50,000 tons of pure water at Kamiokande, Japan, 3,000
feet underground to avoid contamination by cosmic rays. The lake,
like several other underground bodies of water, has been
constantly monitored for flashes of so-called Cerenkov radiation
that occur when a molecule of water disintegrates, but without
success.
The idea behind these experiments is that proton
decay is a random process. Testing for it is like throwing dice.
There's more chance of throwing a six if many dice are thrown
rather than just one. So there's a greater chance of seeing proton
decay if huge numbers of protons are observed, since a few protons
would be decaying all the time. Hence these underground lakes.
But nothing has been found. In the words of Peter
Woit, of Columbia University, New York: “It is becoming
increasingly unlikely that proton decay occurs at an
experimentally observable rate.” Or, as some might say, it is
becoming increasingly unlikely that it occurs at all.
So for how long will the universe remain habitable?
For how many years could a deity be expected to rule over it, if a
deity existed? If protons do not decay, we can contemplate a far
more optimistic vision of the extreme long-term future. Back in
1979, the great physicist Freeman Dyson did an astonishing
calculation of the amount of time in which life could continue.
See his paper “Time Without End: Physics and Biology in an Open
Universe”, (www.aleph.se/Trans/Global/Omega/dyson.txt).
Dyson
believes that the acceleration of the expansion of the universe
may be a temporary phenomenon. If it is, then intelligent life
will be possible in the cosmos for:
10 to the power of (1076)
years
Note the brackets surrounding
the upper two numbers. This is an inconceivably gigantic number.
No imaginable computer could handle it. To write it down in the
ordinary way, using digits like 123456.... etc, even if one could
write down a trillion digits every second, would take no less than
1084 years!
We are looking forward to a time long after all the
stars have ceased to shine, even those that have not yet been
born, when there is no longer any hydrogen to make them shine.
But there is no reason why advanced beings should
not continue to exist, in sunless temperatures only a few tens of
degrees above absolute zero.
They
might take the form of intelligent clouds of gas, as in Fred
Hoyle's 1957 novel The Black Cloud. Perhaps, to quote
Dyson, they could dwell in a “universe growing without limit in
richness and complexity, a universe of life surviving forever and
making itself known to its neighbours across unimaginable gulfs of
space and time.” What gods will these beings worship? |
