The reader's edition
Six Impossible Things: The Mystery of the Quantum World: the summary
John Gribbin is a British science writer trained in astrophysics, and the author of many popular books on physics, including In Search of Schrödinger's Cat. Six Impossible Things is a short book about what quantum physics means, not about how to calculate with it. It first sets out the basic puzzles of the quantum world, including the experiment in which single particles pass through two slits and still build up a pattern of stripes. It then gives a few pages each to six interpretations: Copenhagen, pilot wave, many worlds, decoherence, the ensemble view and the transactional interpretation. The title nods to the White Queen in Through the Looking-Glass, because each interpretation asks you to believe something that sounds impossible. Gribbin presents the book as an agnostic overview: none of the six comes out as better or worse than the others. Read a chapter at a time, with a printable action book at the end.
- John Gribbin
- 2019
- 4 chapters
- 5 min read
- 9 takeaways
This is HourLife's reading of Six Impossible Things: The Mystery of the Quantum World, in our own words. It is not a substitute for the book.
Chapter 01
Before you start
The book in a minute
Tap a paragraph to highlight it. Turn pages with the arrows, the arrow keys, or a swipe.
John Gribbin is a British science writer trained in astrophysics, and the author of many popular books on physics, including In Search of Schrödinger's Cat. Six Impossible Things is a short book about what quantum physics means, not about how to calculate with it. It first sets out the basic puzzles of the quantum world, including the experiment in which single particles pass through two slits and still build up a pattern of stripes. It then gives a few pages each to six interpretations: Copenhagen, pilot wave, many worlds, decoherence, the ensemble view and the transactional interpretation. The title nods to the White Queen in Through the Looking-Glass, because each interpretation asks you to believe something that sounds impossible. Gribbin presents the book as an agnostic overview: none of the six comes out as better or worse than the others.
Below are the 9 ideas HourLife readers vote up most, each in our words with a note on what it asks of you, and then the steps that put them to work.
Chapter 02
What readers keep
The takeaways
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1
HourLife takeaway
Nobody argues about what quantum theory predicts; the fight is over what is really going on.
The equations of quantum mechanics have passed every experimental test so far, to great precision. The interpretations are different stories about the same results. That is why Gribbin can treat all six side by side: none of them is ruled out by an experiment yet.
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2
HourLife takeaway
Every way of making sense of the quantum world asks you to accept one thing that sounds impossible.
The title borrows from the White Queen in Through the Looking-Glass, who practises believing impossible things before breakfast. Gribbin's point is that all six interpretations are crazy in some way. Some are crazier than others, but in the quantum world, crazier does not mean more wrong.
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3
HourLife takeaway
Send particles through two slits one at a time, and they still build up stripes that only waves should make.
Each particle lands as a single dot. Yet after thousands of them, the dots form an interference pattern, as if each one had passed through both slits. Put a detector at the slits to see which way each particle went, and the stripes disappear. Every interpretation in the book has to explain this.
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4
HourLife takeaway
The Copenhagen view tells you to stop asking what a particle does when nobody is looking.
This is the interpretation associated with Niels Bohr, and the name came from Werner Heisenberg. The wave describes what you can know, and a measurement turns the spread of possibilities into one result. It became the textbook answer, and Gribbin shows how much it leaves unexplained.
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5
HourLife takeaway
In the pilot-wave picture the particle always has a real path, steered by a real wave.
Louis de Broglie proposed the idea in the 1920s, and David Bohm revived it in the 1950s. The wave goes through both slits and the particle through one, guided by the wave. The price is that the wave links everything at once, so what happens here depends on the whole set-up, however far apart its parts are.
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6
HourLife takeaway
Many worlds removes the collapse of the wave, at the cost of every possible outcome being real somewhere.
Hugh Everett's idea from the 1950s keeps the equations exactly as they are and never lets the wave collapse. Instead, each measurement splits reality into branches, one for each outcome. It is the simplest maths and the largest universe.
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7
HourLife takeaway
Decoherence explains why the everyday world looks single and solid, even if the quantum world underneath is not.
A quantum system is never truly alone. Air, light and the measuring device all interact with it, and that contact washes out interference very quickly. The question this leaves open is why you then see one particular outcome.
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8
HourLife takeaway
The ensemble view says the wave describes a long run of experiments, never a single particle.
An ensemble can be many identical trials, such as one electron sent through the same set-up a million times. Read that way, quantum theory is statistics and nothing more, which is why it is called a non-interpretation. It looks sensible until the system starts to interact with the world around it, and puzzles such as the watched pot, where a closely watched system does not change, start to bite.
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9
HourLife takeaway
The transactional view lets waves run backwards in time, so every event is a handshake between past and future.
Physicist John Cramer's interpretation has an offer wave going forward from the source and an answering wave coming back from where the particle will land. Where they meet, the transaction is complete. The equations allow waves in both directions of time; this view takes both seriously.
Chapter 03
Put it to work
Your action book
Do the setup steps once, then keep the habits going. The setup changes your week; the habits keep it changed after the first good one.
The download puts this whole reading and a printable action book in one PDF: the setup checklist, then a page of real calendar days for each habit, starting on the day you choose.
Set up once
Run the two-slit experiment
Use the simulator on this page. Fire particles one at a time until the stripes appear, then switch on the detector and watch them go. Write one sentence about what surprised you.
Make stripes with light at home
In a dark room, shine a laser pointer through two thin slits cut close together in kitchen foil, or past a single hair, onto a wall a few metres away. Look at the wall, never into the beam.
Write six index cards
Give each interpretation one card: its name, who proposed it, and the one impossible thing it asks you to accept, in your own words. Check them against the book.
Pick your impossible thing
Choose the interpretation you would rather believe and write two lines on why. Add one line on what evidence would change your mind.
Read the White Queen's chapter
Read chapter 5 of Lewis Carroll's Through the Looking-Glass, Wool and Water, where the title comes from. It is short, out of copyright and free online.
Keep it up
Explain one idea a week
Once a week, explain one interpretation to a friend in two minutes, without jargon. Where you get stuck is the part to reread.
Split what was seen from the story
When you read a science headline, write down what was actually measured, then the story told about it. Notice how often the two get blurred.
State the other view fairly
Before you argue a point this week, say the opposing view in a form its holder would accept. Gribbin does this for six rival stories in a row.
Chapter 04
The last word
Before you go
Pick one step from the action book and do it today. An idea from a book starts to count once it changes what one ordinary day looks like.
Quantum physics never tells you which story is true. It only tells you that every story costs one impossible thing.
That is the end of our reading. Where to go from here, or go back to the full Six Impossible Things: The Mystery of the Quantum World page.
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