Goodreads helps you keep track of books you want to read.
Start by marking “Through Two Doors at Once: The Elegant Experiment That Captures the Enigma of Our Quantum Reality” as Want to Read:
Through Two Doors at Once: The Elegant Experiment That Captures the Enigma of Our Quantum Reality
Enlarge cover
Rate this book
Clear rating
Open Preview

Through Two Doors at Once: The Elegant Experiment That Captures the Enigma of Our Quantum Reality

4.23  ·  Rating details ·  415 ratings  ·  82 reviews
One of Smithsonian's Favorite Books of 2018
One of Forbes's 2018 Best Books About Astronomy, Physics and Mathematics
One of Kirkus's Best Books of 2018

The intellectual adventure story of the "double-slit" experiment, showing how a sunbeam split into two paths first challenged our understanding of light and then the nature of reality itself--and continues to almost 200 year
Hardcover, 304 pages
Published August 7th 2018 by Dutton Books
More Details... Edit Details

Friend Reviews

To see what your friends thought of this book, please sign up.

Reader Q&A

To ask other readers questions about Through Two Doors at Once, please sign up.

Be the first to ask a question about Through Two Doors at Once

Community Reviews

Showing 1-30
Average rating 4.23  · 
Rating details
 ·  415 ratings  ·  82 reviews

More filters
Sort order
Start your review of Through Two Doors at Once: The Elegant Experiment That Captures the Enigma of Our Quantum Reality
Manuel Antão
May 08, 2019 rated it really liked it
Shelves: 2019
If you're into stuff like this, you can read the full review.

(phtn = h * c): “Through Two Doors at Once - The Elegant Experiment That Captures the Enigma of Our Quantum Reality” by Anil Ananthaswam

“If it crossed your mind that human consciousness is somehow involved in causing the photon to behave one way or the other [particle vs. wave], you wouldn’t be alone in thinking so.”

In “Through Two Doors at Once - The Elegant Experiment That Captures the Enigma of Our Quantum Reality” by Anil Ananthasw
Aug 26, 2020 rated it it was amazing
Shelves: physics
If you are fascinated by the classic double-slit experiment this is your book. Written for the nonscientist in straightforward language, it is for readers with a strong interest in quantum mechanics. Of popular physics books I have read, this one is unique in its focus on the double-slit experiment. Most of the experiments use an interferometer to duplicate and go beyond the original experiments. One experiment traverses over 100 kilometers going between two islands. Ananthaswamy uses each exper ...more
David Katzman
Jan 09, 2019 rated it it was amazing
Ananthaswamy introduces extremely complicated ideas in a friendly conversational manner. Admittedly, even for those familiar with quantum physics, it’s easy to get lost in some of the experiments and theories. But despite the times when I was lost, it was a fantastic overview of many of the current diverse theories that attempt to explain the mysteries of quantum physics.

The Double-Slit Experiment is one of the earliest physical experiments that demonstrates many of the mind-bending attributes o
Brian Clegg
Aug 20, 2018 rated it it was amazing
It's sometimes hard to imagine that there's anything new to say about the basics of quantum physics, yet Anil Ananthaswamy manages this in a twofold manner (appropriately, given the title). Through Two Doors at Once does so by using the double slit experiment as a constant reference point throughout the book, and by bringing in a number of the more modern variants on the experiment which rarely feature in popular accounts of quantum theory.

Strictly, the book should probably be called 'Through Tw
Sep 14, 2020 rated it it was amazing
This book was the Bohm dot com! Have you heard of Bohm, of Bohmian mechanics? Real cool guy with a real cool theory about how the world works. The theory is not very popular (blame the politicians), but I want it to be popular! I'm too dumb to explain it, but you guys should read this, and it'll give you a little introduction. It's a theory to list along with Copenhagen and Many Worlds. Also, don't be mad if you hate this book for the first 70ish pages. It gets much, much better after that. Do y ...more
May 28, 2019 rated it liked it
You face 2 doorways: 1) This book sits on a table beside a nice comfy chair or 2) A sheet of paper on said table has just four blurry words that are the final sentence of the book, but you have to walk through the doorway to read the words clearly. What do you do? It doesn't matter at all it seems to the author. After all, his last sentence is "The case remains unsolved." But it's the trip that counts. Walk forward, and you've walked through 2 doors at once! Fun and challenging...with a cat, nat ...more
Peter Tillman
Aug 04, 2018 marked it as to-read
"Richard Feynman said that the double-slit experiment seemed to have been ‘designed to contain all of the mystery of quantum mechanics.’

Are you facing a difficult decision? Quantum physics may have the answer, says science journalist Anil Ananthaswamy. Type your dilemma into the Universe Splitter app, tap a button, and a signal will be sent to a laboratory in Switzerland. A message will come back telling you which choice to make, along with the assurance t
Dec 25, 2018 rated it it was amazing
Gets at the foundations of quantum physics by detailing the history of a specific type of experiment. Well worth it even for those of us who don’t think we want to read another popular book on quantum physics. Very rewarding read.
Ken Rideout
Sep 07, 2018 rated it it was ok
The first half of this book is simply a thorough review of Young's Two Slit experiment as it applies to quantum mechanics. If you've ever taken a first year physics course you will find nothing new here.

The second half is much more interesting as the author takes you a tour of the more recent, mind boggling tests of entanglement in quantum physics which seem to definitively prove Einstein wrong and imply the Universe is non local in someway. However, even though the results are fascinating, I fo
R Nair
Sep 10, 2018 rated it it was amazing
The initial apprehension that this may be the retelling of the same double-slit experiment that is contained as an introduction to quantum mechanics in most text books is needless. Instead the author uses the double slit as a thread winding its way through the different approaches to quantum mechanics and the complex modern experiments that essentially boil down to it. Also one of the best non-technical explanations of quantum Bayesianism (QBism) in recent times. All in all a great book to look ...more
Santiago Ortiz
Experiments and their -sometimes astonishing or even confusing– results are the true doors to physics, and they should precede interpretations and model equations.

"I will not describe it in terms of an analogy with something familiar. I’ll simply describe it."
Mar 19, 2019 rated it it was amazing
Hell of a book. 10/10 would recommend.
Aug 19, 2018 rated it it was amazing
Do you know about the double slit experiment? Well, you only think you do. The double slit experiment wasn't just done 100 years ago and then physicists moved on. Variations on this well-known experiment are happening today with significant implications for our modern understanding (or lack thereof) of quantum mechanics.

When I read a book like this, I'm reminded how lacking science education can be at times. If the double slit experiment is covered in physics or chemistry classes, it's usually
Jun 01, 2019 rated it it was amazing
This short book treads territories where no other popular books on quantum physics have gone for this reader. And it glides through the difficult terrains in the most understandable ways possible.

Quantum physics beyond the uncertainty realms and Copenhagen interpretation is complicated to make sense of. Both thought experiments and their real-life versions, many including the double slits, are hard to follow in implications and on their importance. Mr. Ananthaswamy wastes no time on concepts usu
Jonna Higgins-Freese
Oct 05, 2018 rated it it was amazing
I loved this, because I am currently obsessed with quantum physics and physics in general. This was a great explanation of the history of these experiments and the different ways in which they can be interpreted -- and the further experiments that flow from those interpretations.
Jan 15, 2019 rated it liked it  ·  review of another edition
In another world, I gave this book 5 stars.
Dinesh Krithivasan
Jan 13, 2019 rated it liked it
Anil tries gamely to give the reader an overview of the many schools of thought currently extant in QM through the lens (hah) of the double slit experiment. I remember the experiment fondly because a variant (with the slits immersed in some kind of liquid) was a question in one of my entrance exams and which I knew how to solve. I followed along for the first few chapters but the complexity of it all and the need to follow stuff like entanglement without recourse to mathematics quickly overwhelm ...more
Aug 04, 2020 rated it really liked it
This is my second Ananthaswamy book. I like his style. He mixes science, journalism, and history very well.

I enjoyed the history and progression of ideas. Each interpretation of the double slit experiment sounded perfect, but I knew something better was coming because the book wasn't finished.

Overall it's not very practical. This book won't make you a better person or help you out in life, but if you're curious about quantum physics or wildly interesting ideas/experiments. This book is perfect.
Roberto Rigolin F Lopes
Newton (1643-1727) suggested that light is made of particles but Huygens (1629-1695) formulated a wave theory of light. Particles or waves? Both! (you can shout today). But in 1793 Thomas Young came up with a simple experiment showing that light behaves as a wave. In a dark room, he made a small hole in the window-shutter, using a needle, to let a ray of sunbeam enter the room. Then, he brought into the beam a small piece of paper (85 mm), and studied its shadow to see the diffraction pattern of ...more
Aravind Nagarajan
Jan 11, 2019 rated it it was amazing
Simply mindblowing. Quantum mechanics has always been a topic of interest but a very daunting exercise to read because of the sheer volume of work out there.
The book does a great job of explaining the evolution, philosophy, and differing opinions through the lens (or slits) of a single (double?) experiment.
Thoroughly enjoyed it. Can't say that I understand the subject fully, specially the last two chapters on Everett's Many Worlds Interpretation and Penrose/GRW's quantum gravitation. Definitely
Carmen Tracey
Mar 05, 2019 rated it really liked it
This book was very clearly written and concise, and it was definitely an enjoyable read. I listened to the audiobook version, and the narrator did a great job. I don't think I'm ever going to understand quantum physics, though. :D
Sudharshan Viswanathan
Sep 10, 2018 rated it it was amazing
Shelves: science, education
My attempts at trying to understand QM is restricted to a first course in Undergraduate level. It was sufficiently discouraging for me to never bother attempting to try to understand it again.

Curiously enough, my physics professor has been a big fan of the Young's Double Slit experiment. An introduction to YDSE at high school gave a very wave like treatment to explain the interference patterns.

Now, arriving at this book - I would think that this was the best way of probably introducing someone
Chris Esposo
Jun 21, 2020 rated it it was amazing  ·  review of another edition
Half of this book is an excellent, well-structured, introduction to the wave-particle duality phenomena, and entanglement, with emphasis of setting up, and analyzing, Mach-Zehnder interferometers to understand these unintuitive and abstract phenomena. The other half, though not as instructional, nor grounded as the first, is still a great introduction to alternative (non-Copenhagen) theories of quantum mechanics, and most importantly, introduces a category system for one to compare/contrast the ...more
Jerry Pogan
Nov 16, 2018 rated it it was amazing
Probably one of the smartest things I've ever done in my, almost, 72 years was to not choose Quantum Physics as a career path (Not that I actually ever considered it). The reason is because of all the things I'm woefully ill equipped to understand this is at the top of the list. I simply can't wrap my head around it. I've read dozens of books on the subject and this book, probably, comes closest to being somewhat comprehensible to me. Sarah (one of the Goodread reviewers I follow) said it best w ...more
Sep 18, 2018 rated it liked it
I think it’s about time to quit hoping that someone will be able to dumb-down quantum physics to the point that I understand everything I know. This was a decent effort (I think Carlo Rovelli does it as well as anyone). I believe that the best thing about this book was the insightful anecdotes about some of the giants of the field. Some of them even made me feel better about my lack of understanding-apparently even Einstein got a few things wrong. A worthwhile read for those with an interest in ...more
Sarah S
Feb 07, 2019 rated it did not like it
Shelves: didn-t-finish
I got this book because of the excellent reviews. I read a third of the book. It's a bit tedious for me as I accept nature's indeterminism. The whole of it I've read so far is presenting indeterminism and all the characters being baffled - most people are baffled by it - when will it get to the point. I am too impatient to find out.
Mar 13, 2019 rated it it was ok
Started off with a bang - wonderful delineation of the original thought experiment. Unfortunately it then dragged on, didn't love it enough to finish.
Jun 02, 2019 rated it liked it
No fault of this book that I was too stupid to understand anything and then took out my frustration on the one thing I had control over, its rating. But it's your fault I'm not smart Anil, your fault. Be better.


Thomson had discovered the electron. He, however, called them corpuscles. Thomson speculated these were literally bits of atoms.

Newton’s laws mandated that orbiting electrons had to be accelerating, if they were to remain in their orbits without falling into the nucleus. And Maxw
Sep 10, 2019 rated it it was amazing
Great read for the lay reader who's read a bit about quantum physics but wants to grok it.

Ananthaswamy guides the reader through the basic conundrum the double-slit experiment has broken brains with for a couple of centuries, then through all the models that might explain it, especially those since what is called "the Copenhagen Interpretation" (the first Bohr/Heisenberg et al quantum model that predicted subatomic particle behavior with probabilities).

Supposedly Einstein was troubled by two asp
Ron Peters
Sep 16, 2020 rated it really liked it  ·  review of another edition
I think of myself as a ‘realist,’ someone who likes to see data on the actual state of the world before making my mind up about things. But what are you supposed to do if there is no actual state of the world, just some unimaginable cloud of probabilities where all possibilities cohabit in a blob? Until, apparently, you look at it.

In the two-slit experiment, you shine a light against a barrier with two slits in it then observe what happens as the light hits a screen placed behind the barrier.

« previous 1 3 next »
There are no discussion topics on this book yet. Be the first to start one »

Readers also enjoyed

  • Einstein's Unfinished Revolution: The Search for What Lies Beyond the Quantum
  • Beyond Weird
  • What Is Real?: The Unfinished Quest for the Meaning of Quantum Physics
  • Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime
  • Your Brain Is a Time Machine: The Neuroscience and Physics of Time
  • Lost in Math: How Beauty Leads Physics Astray
  • Livewired: The Inside Story of the Ever-Changing Brain
  • Quantum Space: Loop Quantum Gravity and the Search for the Structure of Space, Time, and the Universe
  • Until the End of Time: Mind, Matter, and Our Search for Meaning in an Evolving Universe
  • Atom Land: A Guided Tour Through the Strange and Impossibly Small World of Particle Physics
  • Complexity: The Emerging Science at the Edge of Order and Chaos
  • The Quantum Labyrinth: How Richard Feynman and John Wheeler Revolutionized Time and Reality
  • The Order of Time
  • When Einstein Walked with Gödel: Excursions to the Edge of Thought
  • The Simulation Hypothesis
  • Reality is Not What it Seems: The Journey to Quantum Gravity
  • The Demon in the Machine: How Hidden Webs of Information Are Solving the Mystery of Life
  • Faraday, Maxwell, and the Electromagnetic Field: How Two Men Revolutionized Physics
See similar books…
ANIL ANANTHASWAMY is former deputy news editor and current consultant for New Scientist. He is a guest editor at UC Santa Cruz’s renowned science-writing program and teaches an annual science journalism workshop at the National Centre for Biological Sciences in Bangalore, India. He is a freelance feature editor for the Proceedings of the National Academy of Science’s “Front Matter” and has written ...more

Related Articles

For more than a decade, Neil deGrasse Tyson, the world-renowned astrophysicist and host of the popular radio and Emmy-nominated...
82 likes · 14 comments
“What Born realized was that the symbols Heisenberg was manipulating in his equations were mathematical objects called matrices, and there was an entire field of mathematics devoted to them, called matrix algebra. For example, Heisenberg had found that there was something strange about his symbols: when entity A was multiplied by entity B, it was not the same as B multiplied by A; the order of multiplication mattered. Real numbers don’t behave this way. But matrices do. A matrix is an array of elements. The array can be a single row, a single column, or a combination of rows and columns. Heisenberg had brilliantly intuited a way of representing the quantum world and asking questions about it using such symbols, while being unaware of matrix algebra.” 0 likes
“The fact that we are now dealing in probabilities is not, presumably, because we do not know enough about the particle. Matrix mechanics says you have all the information you can possibly have. Yet, if you take a million identically prepared particles in the same state (the same combination of states A and B) and perform a million identical measurements, then, on average, x2 number of times you will find the particle in state A, y2 of the time you’ll find it in state B. But you can never predict the answer you’ll get for any single particle. You can only talk statistically. Nature, it seems, is not deterministic in the quantum realm.” 0 likes
More quotes…