How to Build a Time Machine: The Real Science of Time Travel

From the Publisher

"In ‘How to Build a Time Machine’ we start each chapter with an affirmation; ‘Yes, time travel is possible …’.  There’s clarification, ‘ifs’, often detailed historic references; consequences; and then the practicalities – at which point you might have the feeling that it’s not possible after all.  But then there’s the ‘Or is it?’, and one cannot but take the bait and turn the page (loop). To name but a few, what does the following have to do with time-travel?: near-light speed travel; an infinitely long cylinder built from dust - or a less ambitious one (!) built from Neutron stars; Wormholes; Paradoxes; Black/White Holes; Antimatter;  Dark Energy…?  If you’re like me when presented with such a list - appetite whet to the point of drooling - this is a book written with you in mind!  One last and very important point: Clegg is both a writer and a Physicist; and it’s as a writer – one who is able to communicate physics to the non-specialist – and that makes this book so very enjoyable.  The hard stuff is there; between the lines; but we’re not asked to deal with it – Clegg leads us through, in his own imitable style! There are just two equations: Einstein’s E=MC2 (of course!), and Maxwell’s – the latter because they’re so “beautifully spare and simple looking”. Perfect."  - Dr. Peet Morris of Oxford University

Library Journal

Kirkus Reviews

Not quite a how-to, but a survey of the science behind time travel--if anyone ever invents it.

British pop-science writer Clegg (Inflight Science: A Guide to the World From Your Airplane Window, 2011, etc.) notes that time travel is not just a trope of science fiction any more. Increasingly, serious physicists accept that travel to the future and back, or to the past and back, is theoretically possible. The laws of physics provide a few interesting options, and examining them provides an opportunity to look at some interesting corners of modern science. Einstein's theories of special and general relativity describe how motion and gravity affect objects and people. Movement at high speeds, or in powerful gravity fields, changes the rate at which time flows. GPS systems have to adjust for discrepancies between clocks in orbit and those on the ground. These effects can slow time down so travelers can visit distant futures without living through all the years between. Of course, there are problems with these theories: Gravitational fields strong enough to slow time also create tidal forces that can rip matter apart. Other theoretically feasible methods of time travel require building structures such as cylinders of infinite length--hardly a practical option. Clegg also dissects schemes such as going into the past and playing the stock market armed with foreknowledge of what will rise or fall. He covers most of the themes advanced by science fiction, plus some of the more adventurous scientific minds, generally avoiding math or tricky technical details.

A solid overview of some of the quirkier corners of physics, with an entertaining connection to pop culture.