The End of Everything

(Astrophysically Speaking)

By Katie Mack
The End of Everything by Katie Mack book cover
Find it on Bookshop


I know from personal experience how hard it is for a scientist to forget everything we’ve learned about technical science writing in order to write for a more general audience. Dr. Katie Mack has managed this spectacularly, with grace and humor.

I imagine Dr. Mack and her editor constantly fighting about the tone of the book during its writing. There is a perfect balance of handling the seriousness of the subject with a lightheartedness that makes it all okay. Dr. Mack keeps it together (mostly) in the text, but the footnotes do not hold back, and I am here for them.

Even without the dark energy complication, an expanding universe can be a hard thing to wrap your head around*. [*Not literally, obviously. That would be both impossible and extremely inadvisable.]

Most people probably imagine cosmologists as super smart, boring, and stuffy. Smart: yes. Boring and stuffy: no way. Dr. Mack is relatable: excitable, funny, and still impressed by the discoveries happening in her field. She doesn’t shy from blowing her own mind, and does a good job of communicating the strangeness to her reader, sprinkling some pop sci fi culture references along the way.

Some Astrophysics

It’s not that we just trust that math is fundamental to the universe, it’s that there doesn’t seem to be any other way to approach these things that makes any sense.

Dear reader, physics gets weird.

Even as a (marine) scientist interested in physics and space, I learned a lot from this book. I now understand the difference between a Grand Unified Theory and a Theory of Everything (thanks, gravity). And that while nothing can travel faster than light, things can “happen to find themselves farther apart because they are sitting still in a space that’s getting bigger between them.” (WHAT??? 🤯)

There are also a fair number of mindblowers in here. For example, normally, objects look smaller when they are farther away. But once you get out to a certain distance, the farther something is away, the larger it appears! This is because when the light was emitted, they were closer and covered more of the sky.

Also, apparently, there is a moment from zero to 1/[1-with-43-zeros] of a second after the Big Bang called Planck Time, after which we think we can explain what happened but during which we definitely cannot. This moment has a name and number, Mack says, “because we need to quantify exactly how confused we are”.

The End of the Universe

[The possibility that the universe might suddenly blink out of existence] is, of course, one of the most fun things I’ve ever worked on, hence this book. I’m not sure why I like it so much. It may be a bad sign.

Let’s get to the reason you are probably here: how will the universe end? There are 5 options.

  • Big Crunch- universe doesn’t expand enough and collapses in on itself (unlikely)
  • Heat Death- entropy increases until there are no more energy gradients and nothing can happen (likely eventually)
  • Big Rip- dark energy rips the universe apart
  • Vacuum Decay- Higgs field moves from false vacuum to true vacuum via fluctuations or tunneling (we have no idea how likely this is or when it will happen)
  • Bounce- the Big Bang separated two branes (membranes), which will eventually attract back together and bounce off each other

Don’t take my word for it though. I highly recommend you read the full book to understand exactly how these endings were discovered and what they will mean for our universe.

You shouldn’t worry about vacuum decay. Really. For several reasons. There are obvious ones, of course: there’s no way to stop it if it’s happening; and you can’t know it’s about to; and it’s not like it would hurt; and no one would be around to miss you anyway, so what’s the point of worrying about it? You’re better off double-checking your smoke alarm batteries and, I don’t know, lobbying to close down coal power plants or something.

What Does It All Mean?

At the end of a book that can admittedly be a bit of a downer, Dr. Mack does us the emotional favor of reminding us that considering the end is really a way of appreciating the present. And doesn’t knowing there is an end give our existence meaning?

Want to read more? Find The End of Everything here: Bookshop

This book made it onto my list of best nonfiction books of 2021! See the full list here.

The quotes above were gathered using Readwise. It’s a truly amazing app to help you remember what you read. If you want to try it out, use my link and we both get a free month 🙂

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