Midnight Library & Micromorts

measuring regrets & death risk

Several nights ago, I could not sleep, and craved the comfort of a novel. I hopped on Amazon and downloaded Matt Haig’s The Midnight Library. I knew little to nothing about the story, but the title sounded cool and slightly esoteric.

In the novel set in England, protagonist Nora Seed lives a miserable existence full of regrets and chooses to kill herself via an overdose. She wakes up in a library with her childhood librarian, Mrs. Elm, waiting for her. The librarian lets her know she is in the Midnight Library, what appears to be a halfway point between life and death.

In the endless library, there are an infinite amount of books full of Nora’s lives in parallel universes. These are all lives where Nora made different decisions. And she gets to choose a new life to live. The catch is, once she is disappointed with the new life, she vanishes back into the Midnight Library.

A few months prior to her overdose, Nora dumped her fiancé two days before the marriage. Once she arrives at the Midnight Library, she chooses a book where she married her fiancé and bought a pub. She thinks that this might make her happy.

When she gets there, she finds out her arrogant husband is a drunk and a cheater, and she is quickly disappointed. And when she is disappointed, she must return to the Midnight Library. So she is gone as quickly as she came.

She quickly realizes that dumping that guy was a good decision after all. The novel goes on like this: Nora chooses a new life, is disappointed, and eventually realizes that she wants to live. She does not want to die anymore.

I finished the novel, and I feel compelled to write about the subject of regrets. Like Sinatra, I’ve had a few myself.

There are lives where I never left the University of Michigan. There are lives where I never met an ex. There are lives where I invested my income in high school into Bitcoin and was rolling in dough right now. But, I’m quite content with this life.

And this novel has certainly helped me realize that my current life is the best one I could possibly be living. There are parallel lives where I never met my group of friends, never adopted my dog Ron, and lost contact with my parents and family. I’m happy I have all of these relationships in my life today.

As someone who enjoys probabilistic thinking, it is impossible to imagine what the probability is that I’m living the life I’m living right now. But, it’s much easier to predict my chance of death.


I met an ex-Amazon computer scientist on Lunchclub and he let me know of a measurement I never heard of: micromorts. Micromorts are a unit of risk defined as a one-in-a-million chance of death.

For example, the risk of death from all causes in the United States (in 2010) was 22 micromorts per day or 8,000 micromorts per year.

Fun facts about micromorts:

  • They were created by Ronald Howard, a decision analysis pioneer and professor at Stanford University.

  • Skydiving (2010-2016) had a death risk of 8 micromorts per jump.

  • Climbing Mt. Everest (1922-2012) had a death risk of 37,932 micromorts per successful ascent.

  • Base jumping (1995-2005) had a death risk of 430 micromorts per jump.

  • Getting a c-section (2013) had a death risk of 170 micromorts per birth

  • Death by murder and non-negligent manslaughter in the US (2012) was 48 micromorts per year

Increases by 1 micromort via:
  • Traveling 6 miles by motorcycle (2009)

  • Traveling 17 miles by walking (2009)

  • Traveling 250 miles in a car (2009)

  • Traveling 12,000 miles in a jet (2009)

  • Smoking 1.4 cigarettes (2013)

  • Every half hour living in New York City in May 2020, during the COVID-19 pandemic

That last one is a bit of a doozy.

Ronald Howard did research into how much people would spend to decrease their death risk by one micromort, and found that the average answer was $50 (1989).

That being said, the law of diminishing returns and marginal utility comes into play. People are less inclined to spend money to decrease micromorts after a certain point. Makes sense. Every additional micromort becomes a little more meaningless.

Back to the Midnight Library.

Should I try to lower micromorts by avoiding high-risk activities like cigarettes, motorcycles, base-jumping, and living in NYC during a global pandemic?

Is that the answer? Or will I be full of regrets like Nora Seed?

Guess we’ll have to wait for a regret measurement1 to be invented.


“Maximax, Maximin and Minimax Regret.” Default, 2021, kfknowledgebank.kaplan.co.uk/maximax-maximin-and-minimax-regret-.

Wikipedia contributors. “Micromort.” Wikipedia, 25 Aug. 2021, en.wikipedia.org/wiki/Micromort.