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Katie Mack

The End of Everything

(Astrophysically Speaking)

Book review by Anthony Campbell. The review is licensed under a Creative Commons Licence.
In about five billion years our Sun will expand to become a red giant, which will put an end to life on this planet. But that will be just a local catastrophe; at some point in the far future the whole universe will come to an end in one way or another. (Just possibly it could happen in the next second.)

People react to this news in different ways—sometimes with tears. Katie Mack, who is a cosmologist, begins and ends her book by describing her own feelings and those of other scientists with whom she has discussed the matter. She herself is not reconciled emotionally to the certainty of our extinction but finds she can only approach the question in scientific terms.

I've done my own scouring of theological and philosophical texts, and while I learned many fascinating things from my studies, unfortunately the meaning of existence wasn't one of them. I may just not have been cut out for it. … As appealing as it sometimes seemed to have the whole story and meaning of life written down for me once and for all in a book, I knew I would only ever be able to accept the kind of truth I could rederive mathematically.
This truth is what Mack presents us with in this book. There are no equations but some diagrams (the details of which are not always easy to see on the Kindle version). Although this is Mack's first book, she has an assured touch and makes a good job of explaining often difficult ideas.

Modern cosmology has been deeply affected by the discovery that the expansion of the universe is speeding up under the influence of the mysterious dark energy. If this goes on the result will be the final disintegration of everything. However, the expansion might reverse at some point, in which case the end would come as the Big Crunch (the opposite of the Big Bang with which it began). It is also possible that it would then start again.

More speculative possibilities also exist. There may, for example, be something called 'phantom dark energy', which could cause the universe to 'unravel'. But at least all the scenarios discussed so far will not happen—if they do—for at least tens of billions of years. But there is another threat which is potentially immediate.

This is vacuum decay. It depends on the Higgs field, a force which is predicted by the Standard Model of physics and whose existence has recently been confirmed by the Large Hadron Collider at CERN. The Higgs is apparently in an unstable state (false vacuum), but, at least in theory, it could abruptly flip into its stable state of true vacuum. If that occured anywhere in the universe, the laws of physics would suddenly change. 'We owe our entire corporeal existence to the fact that the Higgs has settled on the value it has.

For this to happen there would have to be an ultra-high energy event, such as an explosion or the final evaporation of a black hole. A tiny bubble of vacuum decay (true vacuum) would then form.

At the moment it forms it's an infinitesimal speck. But it is already surrounded by a bubble wall of extremely high energy that could incinerate anything it touches.

Then the bubble begins to expand.

This expansion occurs at about the speed of light.
Anything unfortunate enough to be in the bubble's path is first hit by the intensely energetic bubble wall…. Then it undergoes a process that could only be called total and complete dissociation, as the forces that previously held particles together in atoms and nuclei can no longer function.
If it's of any consolation, we wouldn't know anything about it in advance and it would be totally painless.*

On the evidence of this book, Mack has a bright future ahead of her as a science writer as well as a cosmologist. One final thought: some of the ideas in this book have been around for a long time, but others are very recent. Modern cosmology itself is new; the very existence of other galaxies was unknown until the early decades of the twentieth century. How much may our ideas about the future of the universe have changed a hundred years from now?

* cf. Lewis Carroll, The Hunting of the Snark:
In the midst of the word he was trying to say,
In the midst of his laughter and glee,
He had softly and suddenly vanished away—
For the Snark was a Boojum, you see.


%T The End of Everything
s %S (Astrophysically Speaking)
%A Mack, Katie
%I Penguin
%C London
%D 2020
%G ISBN 978-0-241-37234-0
%P 226pp
%K cosmology
%O kindle version, downloaded from Amazon 2020