Black Holes, Wormholes and Time Machines

I thought this book was excellent. I've been fascinated by this subject for years and have attempted (and failed) to read Hawking, Einstein et al because I just found them too complicated and too filled with equations to make sense. I have 2 hons degrees so I don't think I am that stupid (I hope not!) but I just found Hawking and the like to be unreadable- their concepts are not explained in laymans terms and unless you are an expert in quantum mechanics its like wading through treacle. This book, however, was perfect for a dunce(!) like me and the author gave practical examples and diagrams for most of the complicated concepts such as how black holes work and the concept of time. The style of writing is also very accessible and smattered with the author's own personal thoughts and witty observations which I liked as it made it seem more like we were having a conversation rather than him talking at me about subjects that i don;t understand. For example, in the time travel section he uses the film "The Terminator" to illustrate the time travel paradox which having seen the film, was really helpful and I actually understood what he was saying (yay!).The book inevitable throws up more questions that answers but this is the nature of cosmology and science in general I think. There are some fascinating insights into the possibility of time travel and the fact that according to the laws of gravity, it is technically possible and I was blown away by the idea of Planck time (a measurement of time that is so small, there are more planck units in a single second than there are seconds since the universe began). The concept of infinity was also brilliantly explained and it made me realise that the universe in which we live is more mysterious and unfathomable than I ever realised possible. An excellent book which makes this subject understandable. I actually feel more intelligent having read it!!

To someone (like myself) who has little or no knowledge of physics, this book is a REAL eye-opener. It is incredibly exciting, and has a deal of humour to boot.Some parts DO require concentration to get your head around, and I must admit on one or two occasions being slightly lost. Thankfully though 99% of the book was quite easy to follow.Primarily the book is focused on giving the reader an overview of Einstein's Theories of Relativity, and in particular how these could be applicable to time travel.My only slight criticism is that the author does seem to concentrate on building/using time machines from a practical viewpoint, as though the reader is a Sc-Fi fan.Before reading it I thought the universe was born billions of years ago with the Big Bang, and that I was at a certain point in time, and it would carry on ad infinitum after I die. Not necessarily so according to modern physics!A very small sample of amazing information that I learned was:Time could start running backwards if the Universe stops expanding and starts contracting.Time slows down the quicker you go (near the speed of light time almost stops, or speeds up to infinity depending on your viewpoint).Gravity doesn't pull objects, but bends space itself so objects 'fall' into it.Gravity bends time and slows it down. Very heavy gravitation can almost stop time.That the 'present' depends on where you are in space (and your speed), and that all future & past events may co-exist.The book also touches on Quantum Mechanics, which is even weirder i.e. particles appearing from nowhere and being in 2 places at the same time.

Jim Al-Khalili's ambition was to write a book "which would explain some of the ideas and theories of modern physics for anyone to understand" (p.ix) - job (well) done! However, if your ambition is to deepen your understanding of the intricacies of relativity, this may not be the book for you. There are no detailed explanations for the effects of relativity and no elegant proofs to be found within these pages: Al-Khalili simply describes what scientists know - not how they know it.Strangely, this approach works rather well! The absence of dense passages of scientific explanation allows Al-Khalili to take a light-hearted approach to some of the fundamental concepts of modern cosmology (the nature of time, spacetime, and gravity) and then wrap them (no pun intended!) around the effects of gravitational anomalies - the black holes and wormholes of the title. Given the uncertainty that surrounds these phenomena, he is then free to indulge in speculation about the potential for time travel. It's a refreshing approach to the popularization of modern science and reminiscent of Carl Sagan's approach in works such as Pale Blue Dot.This is a fun and enjoyable read from start to finish and, although written with teenagers in mind (p.x) and in a humorous style, it's a great place to start if you have never grappled with the ideas of relativity before - no matter what age you are! Nonetheless, if you are ready for something slightly more challenging, try Neil deGrasse Tyson's Death by Black Hole.

Great, thanks

I read this book a while ago and thoroughly enjoyed. Shame there seems to be no copy available of it at a reasonabl price. I did a full review for it here ([...] for anyone interested in what I thought about it, did not want to copy and paste exact text in here. A really insightful book though.

Love this book. Perfecto for amateurs in the matter.

Started reading the book when I was studying physics at A level but found it a little to much at the time.With a bit more time and space (A shed) to read and think it makes a very thought provoking read.Would recomend it to anyone.Oh and does anyone have any flux capacitors... I just need one more to get this thing working.