Subtitled "The Hunt for Dark Matter and Dark Energy in the Universe" Gates' introduction to astro-physics and cosmology is everything that you would expect of such a book. Gates' tries '''so''' hard to be readable, and mostly succeeds, but at the same time, the subject matter is well-nigh incomprehensible. Or maybe, that's just me.
In fairness, Gates is under no illusions about the difficulty of her subject matter and the potential craziness of trying to write a "popular science" book that people might actually read and seek to understand - as opposed to, say, one that will bought as a present for others on the strength of the name on the cover, but will be doomed to sit on a shelf, looking impressive, contributing very little to accumulated wisdom.
In her preface she tells us that she offers it up "in the same spirit that musicians proffer their music to the world - to be absorbed in many different ways at many different levels". She fundamentally objects to the notion that science is "for professional use only". She asks that we look at the photographs for their aesthetic beauty as well as their scientific value. Finally, she promises that "no prior knowledge of science is assumed ... even if the last science book you opened was an eleventh grade text book, you should be fine." We didn't operate the American "grade" system when I was at school, I'm not sure I even got that far! We did our "options" at the end of the 3rd yr of senior school. There were obligations & other limitations imposed by the groupings. We '''had''' to do English, Maths, at least one science, and at least one language. English, Maths and Languages were never a problem. When it came to science: I got squeamish about biology, chemistry was basically just practical algebra (& so, theoretically at least, a doddle), physics .... I just don't '''get''' physics.
My ever patient other half is still trying to teach me the basics 30 years on.
I opted for history, instead.
Now I find that physics, astrophysics or, if you prefer, cosmology, is really the ultimate history lesson. The history of the universe. Trying to understand everything that is, and how it got here.
Not sure I was going to be able to handle this. Step up Ms Gates with her ever-ready reassurance: "this book is not intended as a course in basic physics, but as a means of transporting the reader to the brink of the most exciting frontier in science today..."
She did that alright. Unfortunately, I think I might still have been the child in the back of the room wondering "are we there yet?"
For those to whom these expressions might mean something, let me first explain what the book does. Gates summarises currently cosmology (which I'll use as a shorthand for astrophysics & the related investigations at sub-atomic level) from Einstein onwards, with the occasional delving into Newton and pre-Newtonian ideas, where these help to explain current thinking.
The "telescope" of the title is gravitational lensing: the bending of light, by the dimpling in space-time, caused by the gravity of a massive object (a star, a galaxy, a cluster of galaxies), which enables us to "see" by inference objects that we cannot see in the visible light or any other readily detectable spectrum.
This is one of the main tools currently being used in the search for the missing matter (and, as it now turns out, missing energy) in the Universe.
If you pay the remotest attention to the science news, you'll know that the boffins speculate that observable matter (i.e. everything in the entire Universe made up of what we might call "stuff" - or even the projected, but not actually proven, "anti-stuff" that is a fundamental part of making a warp drive work) only accounts for about the 5% of the theoretical mass of the place-time.
That's an awful lot of non-stuff to be accounted for. Enter "dark matter" and more latterly "dark energy". Sounding a bit Harry Potter yet?
Some of it actually makes sense. A lot of the posited "dark matter" is actually matter as we know and love it, and the anti-stuff that we're prepared to know and love if it ever manages to stick around long enough for us to make its acquaintance, rather than simply blinking out of existence the second it meets some "matter". This level of dark matter, is matter, just dark i.e. undetectable with our current technology.
Then there's the rest. No matter how much we can realistically factor into the equations, we need a lot more. (By 'we' I mean, 'they'. The people who apparently understand the numbers stuff.) No matter how much unseen matter and antimatter can be reasonably attributed on the basis of physics as it's understood, there are still huge gaps. There is something else out there: Cold Dark Matter. This is something else entirely.
How do they know it's there, if they can't even begin to conceive of what it is? It has to be. Or Einstein's theories don't hold up. And in every other respect they hold up too well.
It's a similar argument when it comes to Dark Energy. On the basis of general relativity, everything more or less works... except that the expansion of the universe (post-big-bang) should logically, under the rules of gravity, slow down. It appears to be accelerating. Something must be driving that acceleration: enter mysterious visitor number 2: Dark Energy.
If I understand Gates correctly, if the jury is still out on Dark Matter (WIMPs, MACHOs?) it hasn't even been empanelled on Dark Energy. This is the current frontier.
She takes us through the theories, with earth-bound analogies to try to get the concepts across, as limiting as these obviously are - and then surveys the current state of the research: who is doing what, how, where, with what equipment, why it might work, what its limitations are.
How well does any of this work as a book for the general reader? "Ask me in two years time!" would come close to an honest answer. I'm not sure yet.
On Gates' original premise, that could mean that it actually works very well. I did, more or less, follow the arguments and theories up to about page 150. Then she started to lose me. On page 174 she regained my attention by saying the one thing I've needed a cosmologist to say blatantly and publicly ever since I started taking an interest:
"their interpretation as evidence for the existence of large amounts of unseen matter relies on one critical assumption: that we understand gravity.
What if this assumption is wrong? What if Einstein's grand theory of gravity - general relativity - is not valid...?"
Wow! She had me back.
I did struggle with many of the concepts in the latter half of the book, and even concentrating enough to follow the argument wasn't easy, but I wanted to know what was coming. I wanted to hear what someone prepared to publicly voice the "what if" had to say.
It turns out that scientists have been quietly working on the what if for quite some time. If Einstein was wrong, we can adjust this side of the equation (gravity) or that side (energy & matter).
The fact that they're not really coming up with any real conclusive evidence that moves them very far from Einstein, brings me back to my personal scepticism, what if the great man was simply utterly totally and completely wrong. What if the equation doesn't need adjusting, what if it needs forgetting?
Until we get a genius of Einstein's standing, someone who can throw the bathwater out without worrying about whether there's a baby in there, we'll never know.
Meanwhile, they use the tools they have, simply because they do seem to work. Mostly.
Gates gets my admiration simply for not shying away from my most favourite phrase in the scientific lexicon: "we don't know". The closer you get to the end of the book, the closer you get to the scientific front end, the more frequently she says maybe, possibly, could be, but we just don't know. She freely admits to the fact that the truth might be something so far beyond our current ability to even conceive of it, much less produce equipment with which to measure the effects that would demonstrate it as a reality. For that alone she is worth reading.
In terms of readability: Einstein's Telescope skips back and forth from the basic explanation to the detailed and barely comprehensible, but it does try. Every new concept is explained with human-scale analogies.
Not an easy book but one that I'm glad I persevered with, and may find myself coming back to.