Book Review: How to Build a Time Machine (Paul Davies)

How to Build a Time Machine by Paul Davies

My rating: 4 of 5 stars

Let's get this out of the way first: time travel like you see in the movies will probably never become a thing. Physics simply doesn't make things like a flux capacitor plausible. Therefore, you ought to know that this book won't help you or anyone else build a working time machine. It's simply not possible with today's technology, and it might never be possible.

That is not to say the book is a waste or doesn't deliver on its promises, because the third chapter does get really deep into the details of a hypothetical model for a time machine that could jive with physics. It's not as easy as you might think: if you don't have a giant spinning cylinder that's as long as infinity, then you're best bet is to create a microscopic wormhole by conjigguring with quantum science (don't even ask me how, quantum mechanics is my biggest blind-spot). But then you'd have to solve bigger problems, such as how to keep it open for longer than a trillionth of a second or so. And you'd have to enlarge it, probably with matter that gives off antigravity, which may or may not exist. Then you'd have to pump it full of negative energy, which can either be found in black holes, or generated with some crazy contraption involving mirrors and lasers the size of the solar system. If you manage all that, then congratulations, you made a singularity. There's a lot more details to it--I think part of the process involved hurling a bunch of nukes at it. You know what you can do with your wormhole then? You can either wait for so-many years to use it, so you can go back in time to the point the thing was made. Or you can drag the wormhole to a stellar body and use time dilation to go back in time, potentially beyond the time machine's invention. Maybe.

If it sounds too incredible to ever happen, then you can see the real value of the book: it underscores just how complex space and time are interconnected, and it lays out the reasons why time travel in sci-fi is so implausible. The book is a pretty short, breezy, high-level examination of basic relativity--if you know about it going in, it's nothing new. Newcomers might struggle a bit to grasp these concepts, but I think Davies does a good job of relaying the information in simple, laymen's terms. There are more advanced theories and concepts that lie beyond the scope of the book (such as String Theory, M Theory, Multiverse Theory), but I'm glad it doesn't over-complicate things.

For an aspiring sci-fi writer like myself, this book is a pretty brisk and enlightening read--a firm reminder of how scientific theory actually works and how unlikely it is that we'll ever have a working time machine. Casual and curious readers ought to give it a try--it might be something you know about already, but designing a plausible time machine is an interesting thought experiment.