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.
Advertisement
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.