How to Build a Time Machine by Paul Davies, Allen Lane,
拢9.99, ISBN 0713995831
GREAT, I thought. Just tell me how to build that time machine. I鈥檒l whiz off
to check out the grandchildren. . .
Paul Davies, doyen of popular books about time, has produced an easy read
with no index and nearly as many pictures as words (diagrams explain the quirks
of space-time, but why all the bad line drawings of scientists鈥擟arl Sagan,
for example, a well-favoured man, looks like a vampire with caries?). Some of
the knottier physics 鈥渘eed not concern us here鈥�, says Davies. 鈥淲hat matters. . .
is that time is elastic.鈥� If you accelerate far enough, fast enough, less time
will pass for you than for those you left behind; hover near a super-dense
neutron star, and gravity will slow time by 30 per cent; harvest a wormhole from
the space-time foam, and you may be able to visit the past or the future, and
change the present.
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But before you can build your time machine, you need to stabilise your
wormhole with 鈥渁ntigravity鈥� (very hard to do) from a generous source of
鈥渘egative energy鈥� (very hard to find). Even if you succeed, you鈥檒l probably get
turned into spaghetti. Davies鈥檚 eventual conclusion undermines the upbeat title.
How do you build a time machine? Errm, sorry, it鈥檚 too difficult and it costs
too much. You can鈥檛.
