Book Review: A Brief History of Black Holes
A fascinating and appropriately densely compact look at the scientific history underpinning the discovery and study of black holes, by astrophysicist and science communicator, Dr Becky Smethurst.
Dr Becky’s YouTube channel is great. I really enjoy the way that she talks about the new discoveries in astrophysics and astronomy. I started watching her videos on and off maybe a year or so before the launch of the JWST, but particularly since the telescope’s launch, her videos have been a great way to keep track of the new discoveries and observations it’s making. I’ve been fascinated by black holes ever since I was a child and so I was quite excited when Dr Becky announced that she was releasing this book (to give it its full title): A Brief History of Black Holes (And Why Nearly Everything You Know About Them Is Wrong). Now, since I’ve been reading about black holes for a long time, the second part of that title didn’t necessarily apply to me. The book pretty much reiterated much of what I already knew about them - though there were a good few bits I didn’t know, such as the co-evolution of supermassive black holes and their galaxies, the theoretical upper limit for the mass of ultramassive black holes etc… So there was still a lot of great stuff in here to learn. Plus being all tightly packed in the one book helped with seeing the relationships between all of these things.
The book goes through right from the very beginning of astronomy and the big physical discoveries - which answered seemingly simple questions like “why do the stars shine?” and “what are they made of?” etc… all tracing a path towards understanding what black holes are, why they form and how they behave, including black hole mergers and gravitational waves. It was great to see how everything was related, and how every discovery in science builds upon the understanding of what came before. The book is also a lot of fun, with nice references and little jokes. I have to admit, I read the entire thing in Dr Becky’s voice as well!
However, missing from the book (or severely downplayed) were certain aspects about black holes that I thought would be given a much deeper explanation. I would have expected to see the first ever accurate image of a black hole, made by Jean-Pierre Luminet in 1979 using nothing but mathematics, an early IBM mainframe, and then drawing with black ink. It showed things like the photon ring outside the event horizon, and the doppler shift of light in the accretion disk (where the side that is spinning towards us is brighter, and the side heading away from us is darker - and the same happens with the colour, with the dark area being more red, and the bright area being more blue, though this wasn’t shown in Luminet’s illustration because it was black and white), as well as the way the light from the part of the accretion disk behind the black hole is visible as an arc over the top of it due to the extreme curvature of spacetime. Sadly this image and its explanation was missing. Likewise, there wasn’t any time spent explaining the differences between a rotating and non-rotating black hole. This was probably for simplicity’s sake - many astrophysicists do work with black holes by initially assuming them as non-rotating. But in fact almost all of them are spinning, conserving their angular momentum from when they were stars (this is very briefly mentioned towards the end), and this does change the dynamics and shape somewhat. Lastly, there was also a slight error I found regarding the designation of the closest black hole to Earth - V616 Monocerotis - which was mislabelled several times as V1616. A simple typo, really, which is usually nothing to be bothered by, but thankfully no “V1616” designation exists and Google simply corrects it to V616, otherwise it would send readers to the wrong object.
These things are fairly minor for an introductory book, though, because it really depends where you approach it from. There is plenty of information in here to be getting on with, and it is all very well presented. The only real negative I could say is that the book does a lot of quick-fire name-dropping and it goes off on tangents often - they’re related tangents, but it sometimes felt like that episode of Malcolm in the Middle where Hal wants to change a lightbulb, but needs to fix a drawer but he doesn’t have a screwdriver so he needs to go the store but there’s something wrong with the car and he has to fix that but he doesn’t have the tools and… In the end he’s basically taking the whole house apart before he can get back to the original task. So it can be a bit overwhelming at times.
Overall, the book is a very enjoyable, entertaining and compact look at the history of black holes as well as other related scientific discoveries with plenty of wit and fun references to pop culture. If you’re someone who is interested in black holes, but hasn’t read about them much before, then this is an excellent introduction that will take you deep enough to get a good grasp on what these objects are like and how we came to know about them.
