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Through Two Doors at Once: The Elegant Experiment That Captures the Enigma of Our Quantum Reality
One of Smithsonian's Favorite Books of 2018One of Forbes's 2018 Best Books About Astronomy, Physics and MathematicsOne 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 years later.Many of science's greatest minds have grappled with the simple yet elusive "double-slit" experiment. Thomas Young devised it in the early 1800s to show that light behaves like a wave, and in doing so opposed Isaac Newton. Nearly a century later, Albert Einstein showed that light comes in quanta, or particles, and the experiment became key to a fierce debate between Einstein and Niels Bohr over the nature of reality. Richard Feynman held that the double slit embodies the central mystery of the quantum world. Decade after decade, hypothesis after hypothesis, scientists have returned to this ingenious experiment to help them answer deeper and deeper questions about the fabric of the universe.How can a single particle behave both like a particle and a wave? Does a particle exist before we look at it, or does the very act of looking create reality? Are there hidden aspects to reality missing from the orthodox view of quantum physics? Is there a place where the quantum world ends and the familiar classical world of our daily lives begins, and if so, can we find it? And if there's no such place, then does the universe split into two each time a particle goes through the double slit?With his extraordinarily gifted eloquence, Anil Ananthaswamy travels around the world and through history, down to the smallest scales of physical reality we have yet fathomed. Through Two Doors at Once is the most fantastic voyage you can take.
303 pages, Kindle Edition
Published August 7, 2018
387 people are currently reading
2414 people want to read
About the author
Anil Ananthaswamy
9 books165 followersANIL 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 for National Geographic News, Discover, and Matter. He has been a columnist for PBS NOVA’s The Nature of Reality blog. He won the UK Institute of Physics’ Physics Journalism award and the British Association of Science Writers’ award for Best Investigative Journalism. His first book, The Edge of Physics, was voted book of the year in 2010 by Physics World. He lives in Bangalore, India, and Berkeley, California.
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Displaying 1 - 30 of 141 reviews
August 26, 2020
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 experiment to illustrate different aspects of the puzzling results. He discusses these with many of the scientists who performed them getting their insights. He even interviews Roger Penrose in Oxford about his pet interpretation of quantum mechanics. The book includes snippets of history of the development of quantum mechanics covering the many different takes on what it means. At the end he runs through the main interpretations but doesn’t take a position on any of them. Ananthaswamy is a science journalist who is well versed in his subject, not a physicist backing one particular view. This nonpartisan approach was refreshing in this type of book.
The heart of the book is about the experiment itself showing us the many ways it has been done over the years. We get useful diagrams of the different interferometer setups with clear explanations of what happens. The first experiments are the simplest. They show the particle-wave duality, the interference pattern created by a single particle and that any sort of measurement or detection causes the particle to take a definite path. While this may seem like standard fare, there are many nuances in the different setups that demonstrate a variety of indirect measurements changing the particle’s behavior. Ananthaswamy goes on to describe experiments using entangled pairs of particles where one contains information about the other and shows that erasing the information reverses the act of measurement reversing the other particle’s quantum state. Particularly stunning is that this reversal works even if that information is erased after the other particle has finished the experiment seemingly going back in time to change the results. As an encore he demonstrates how to detect an object without anything encountering it. The whole series of experiments left my head spinning.
At the end he devotes a few chapters to the interpretations. He pretty much assumes the reader is familiar with the Copenhagen interpretation and goes through the de-Broglie-Bohm theory, GRW theory, QBism, Many Worlds theory and briefly mentions a few others including Penrose’s. He doesn’t favor any one, but believes all should be kept in mind because even if all are wrong, one might lead to a new idea, a new theory that may provide a better explanation. He provides some examples of new lines of thought. But it wasn’t Ananthaswamy review of the theories that made this book a winner. It was his descriptions of the many experiments that made clear that acquiring or erasing any form of information that defined a particles’ path changed its quantum state, even apparently going back in time to do so. Ananthaswamy leaves us with no doubt about how profoundly mysterious the quantum world is.
The heart of the book is about the experiment itself showing us the many ways it has been done over the years. We get useful diagrams of the different interferometer setups with clear explanations of what happens. The first experiments are the simplest. They show the particle-wave duality, the interference pattern created by a single particle and that any sort of measurement or detection causes the particle to take a definite path. While this may seem like standard fare, there are many nuances in the different setups that demonstrate a variety of indirect measurements changing the particle’s behavior. Ananthaswamy goes on to describe experiments using entangled pairs of particles where one contains information about the other and shows that erasing the information reverses the act of measurement reversing the other particle’s quantum state. Particularly stunning is that this reversal works even if that information is erased after the other particle has finished the experiment seemingly going back in time to change the results. As an encore he demonstrates how to detect an object without anything encountering it. The whole series of experiments left my head spinning.
At the end he devotes a few chapters to the interpretations. He pretty much assumes the reader is familiar with the Copenhagen interpretation and goes through the de-Broglie-Bohm theory, GRW theory, QBism, Many Worlds theory and briefly mentions a few others including Penrose’s. He doesn’t favor any one, but believes all should be kept in mind because even if all are wrong, one might lead to a new idea, a new theory that may provide a better explanation. He provides some examples of new lines of thought. But it wasn’t Ananthaswamy review of the theories that made this book a winner. It was his descriptions of the many experiments that made clear that acquiring or erasing any form of information that defined a particles’ path changed its quantum state, even apparently going back in time to do so. Ananthaswamy leaves us with no doubt about how profoundly mysterious the quantum world is.
January 10, 2019
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 of particles, particularly photons and electrons. I was surprised to learn that they’ve even demonstrated these quantum effects with particles larger than atoms. I also had no idea there were so many variations of the Double-Slit Experiment, and that it is still being used to test new quantum theories and variations of existing theories. Significant portions of the book explain this experiment in detail and numerous variations of it. This is where I occasionally got lost. Some of the experimental variations are quite complex. But it’s a worthy effort to follow because—as abstract as quantum theory is—the results of it are borne out in experiments. It’s not just abstract philosophy, it produces results.
By means of the Double-Slit Experiment, Ananthaswamy takes us through two sides of Quantum Mechanics. The strangeness and mysteries of particle behavior and the various theories that attempt to explain that weirdness. And between these two sides sits the Schrödinger Equation that mathematically calculates the behavior of particles going through the experiment (as well as, of course, in other contexts, such as particle behavior around atoms).
The weirdness of quantum mechanics includes, but is not limited to, wave/particle duality, entanglement, spooky action at a distance (also called non-locality), and the very nature of probability versus randomness.
As he takes us through various versions of the experiment, and stories about the various physicists who have contributed to quantum mechanics, he also takes us through a survey of the majority of currently en vogue quantum theories that try to explain the weirdness. From the conservative Copenhagan interpretation to Multiple Worlds Theory to some that I had never even heard of! He explains the strengths and weaknesses of each and what they do and don’t explain successfully. It was fascinating to learn about what some of the holes are, and it certainly appears that there is no entirely satisfactory theory in place yet. For example, the Copenhagan theory fails to explain where the transition occurs from quantum to non-quantum observation. It also forces you to accept non-locality, meaning particles that are billions of miles apart could instantaneously affect each other, far faster than the speed of light. The Multiple Worlds theory solves both of those particular issues (and many others), but it fails to explain what “probability” means in the context of the Schrodinger’s equation. It fails to justify the randomness that we “observe” from repeated experimentation. There are some ideas how to deal with this, but none seem entirely satisfactory yet.
Ananthaswamy does a nice job explaining most of the theories, again, admittedly, with some difficult-to-understand parts. But given the complexity of the issues, I think it was commendable. Overall, a fascinating and wonderful book.
The Double-Slit Experiment is one of the earliest physical experiments that demonstrates many of the mind-bending attributes of particles, particularly photons and electrons. I was surprised to learn that they’ve even demonstrated these quantum effects with particles larger than atoms. I also had no idea there were so many variations of the Double-Slit Experiment, and that it is still being used to test new quantum theories and variations of existing theories. Significant portions of the book explain this experiment in detail and numerous variations of it. This is where I occasionally got lost. Some of the experimental variations are quite complex. But it’s a worthy effort to follow because—as abstract as quantum theory is—the results of it are borne out in experiments. It’s not just abstract philosophy, it produces results.
By means of the Double-Slit Experiment, Ananthaswamy takes us through two sides of Quantum Mechanics. The strangeness and mysteries of particle behavior and the various theories that attempt to explain that weirdness. And between these two sides sits the Schrödinger Equation that mathematically calculates the behavior of particles going through the experiment (as well as, of course, in other contexts, such as particle behavior around atoms).
The weirdness of quantum mechanics includes, but is not limited to, wave/particle duality, entanglement, spooky action at a distance (also called non-locality), and the very nature of probability versus randomness.
As he takes us through various versions of the experiment, and stories about the various physicists who have contributed to quantum mechanics, he also takes us through a survey of the majority of currently en vogue quantum theories that try to explain the weirdness. From the conservative Copenhagan interpretation to Multiple Worlds Theory to some that I had never even heard of! He explains the strengths and weaknesses of each and what they do and don’t explain successfully. It was fascinating to learn about what some of the holes are, and it certainly appears that there is no entirely satisfactory theory in place yet. For example, the Copenhagan theory fails to explain where the transition occurs from quantum to non-quantum observation. It also forces you to accept non-locality, meaning particles that are billions of miles apart could instantaneously affect each other, far faster than the speed of light. The Multiple Worlds theory solves both of those particular issues (and many others), but it fails to explain what “probability” means in the context of the Schrodinger’s equation. It fails to justify the randomness that we “observe” from repeated experimentation. There are some ideas how to deal with this, but none seem entirely satisfactory yet.
Ananthaswamy does a nice job explaining most of the theories, again, admittedly, with some difficult-to-understand parts. But given the complexity of the issues, I think it was commendable. Overall, a fascinating and wonderful book.
August 20, 2018
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 Two Doors at Once and Spooky Action at a Distance plus Things That Have a Similar Effect', as it uses both the double slit experiment and the EPR entanglement thought experiment, plus modern experiments which don't, for example, involve slits but rather beam splitters that are their logical equivalent - but I have to admit, that would be a clumsy title.
Ananthaswamy gives us a good overview of the development of quantum physics - sometimes quite summary - but by making repeated use of the double slit, going all the way back to Thomas Young, but also looking at the quantum specifics, he both helps the reader get a better feel for just why quantum physics can seem strange and also what the different interpretations, from Copenhagen to Many Worlds, tell us about what we can and can't know of what's happening inside the experiment.
The part of the book covering interpretations is perhaps slightly less effective than the rest, because, in the end, unless you are an enthusiast for a particular interpretation, the diversity of ideas tends to obscure, rather than help get a better understanding. (We still have to come back to Feynman's crushing '[Y]ou think I’m going to explain it to you so you can understand it? No, you’re not going to be able to understand it... You see, my physics students don’t understand it either. This is because I don’t understand it. Nobody does.')
The best part of this section is the explanation of the Bohm/deBroglie interpretation where there is both a wave and a particle, though there is one minor problem here, as we are told that making a strong measurement in the Bohm model leaves particles where you don't expect them to be - but are not told why the strong measurement of the particle causing a scintillation on a screen does leave them where we expect them to be.
For me, the only real improvement would have been to put a bit more character into the historical context: it's rather dry and summary. So, for example, we are not told about Einstein's dismissive 'Ist mir Wurst' remark about EPR's confusing use of two measurements. Another example: John Wheeler is described as coining the term 'black hole', rather than giving us the more interesting actual story. There's enough to get the point, but it could have been made more engaging.
Overall, though, Anathanswamy cleverly comes at quantum physics from a different direction, and as a result, adds to the picture we get from most popular titles. We really get into why the double slit plus entanglement are often described as the central mysteries of quantum theory, and though they can still send the brain spinning, there's the best description of many of the more recent experiments I've seen - useful as they can seem a little pointless without this kind of in-depth picture. An excellent addition to the 'Quantum physics for the rest of us' shelf.
Strictly, the book should probably be called 'Through Two Doors at Once and Spooky Action at a Distance plus Things That Have a Similar Effect', as it uses both the double slit experiment and the EPR entanglement thought experiment, plus modern experiments which don't, for example, involve slits but rather beam splitters that are their logical equivalent - but I have to admit, that would be a clumsy title.
Ananthaswamy gives us a good overview of the development of quantum physics - sometimes quite summary - but by making repeated use of the double slit, going all the way back to Thomas Young, but also looking at the quantum specifics, he both helps the reader get a better feel for just why quantum physics can seem strange and also what the different interpretations, from Copenhagen to Many Worlds, tell us about what we can and can't know of what's happening inside the experiment.
The part of the book covering interpretations is perhaps slightly less effective than the rest, because, in the end, unless you are an enthusiast for a particular interpretation, the diversity of ideas tends to obscure, rather than help get a better understanding. (We still have to come back to Feynman's crushing '[Y]ou think I’m going to explain it to you so you can understand it? No, you’re not going to be able to understand it... You see, my physics students don’t understand it either. This is because I don’t understand it. Nobody does.')
The best part of this section is the explanation of the Bohm/deBroglie interpretation where there is both a wave and a particle, though there is one minor problem here, as we are told that making a strong measurement in the Bohm model leaves particles where you don't expect them to be - but are not told why the strong measurement of the particle causing a scintillation on a screen does leave them where we expect them to be.
For me, the only real improvement would have been to put a bit more character into the historical context: it's rather dry and summary. So, for example, we are not told about Einstein's dismissive 'Ist mir Wurst' remark about EPR's confusing use of two measurements. Another example: John Wheeler is described as coining the term 'black hole', rather than giving us the more interesting actual story. There's enough to get the point, but it could have been made more engaging.
Overall, though, Anathanswamy cleverly comes at quantum physics from a different direction, and as a result, adds to the picture we get from most popular titles. We really get into why the double slit plus entanglement are often described as the central mysteries of quantum theory, and though they can still send the brain spinning, there's the best description of many of the more recent experiments I've seen - useful as they can seem a little pointless without this kind of in-depth picture. An excellent addition to the 'Quantum physics for the rest of us' shelf.
September 8, 2018
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 found the detailed explainers of the experiments and the back stories of the scientists exhaustively detailed. Finally, the author spends some time on the various non Copenhagen interpretations of Quantum Mechanics. This is arguably the most important part of the book and, yet, somehow also got bogged down in the backstory of the personalities involved and suffered from a muddled exposition (at least it was hard for me to extract the key differences).
The idea of keeping the double slit experiment central to the explorations of all the big ideas in quantum physics is a cool one, but ultimately the book felt to me like it wandered all over the place (like ideas about the meaning of the wave function itself). I did finish with a much better understanding of the philosophical problems in the Copenhagen Interpretation (namely, the arbitrary nature of the wave function collapse) and a better understanding of Bell's Theorem, but I don't think I will be recommending this particular book to anyone looking to explore the philosophy of quantum mechanics.
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 found the detailed explainers of the experiments and the back stories of the scientists exhaustively detailed. Finally, the author spends some time on the various non Copenhagen interpretations of Quantum Mechanics. This is arguably the most important part of the book and, yet, somehow also got bogged down in the backstory of the personalities involved and suffered from a muddled exposition (at least it was hard for me to extract the key differences).
The idea of keeping the double slit experiment central to the explorations of all the big ideas in quantum physics is a cool one, but ultimately the book felt to me like it wandered all over the place (like ideas about the meaning of the wave function itself). I did finish with a much better understanding of the philosophical problems in the Copenhagen Interpretation (namely, the arbitrary nature of the wave function collapse) and a better understanding of Bell's Theorem, but I don't think I will be recommending this particular book to anyone looking to explore the philosophy of quantum mechanics.
Want to read
August 4, 2018https://www.wsj.com/articles/through-...
"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 that there is now another universe where your double can opt for the alternative.
Mr. Ananthaswamy was shown this high-tech coin toss by Sean Carroll, a professor of theoretical physics at Caltech and an advocate of the “many worlds” interpretation of quantum mechanics. Mr. Ananthaswamy’s “Through Two Doors at Once” is a challenging and rewarding survey of how scientists like Mr. Carroll are grappling with nature’s deepest, strangest secrets. ..."
"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 that there is now another universe where your double can opt for the alternative.
Mr. Ananthaswamy was shown this high-tech coin toss by Sean Carroll, a professor of theoretical physics at Caltech and an advocate of the “many worlds” interpretation of quantum mechanics. Mr. Ananthaswamy’s “Through Two Doors at Once” is a challenging and rewarding survey of how scientists like Mr. Carroll are grappling with nature’s deepest, strangest secrets. ..."
September 15, 2020
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 you know how to detect a bomb without detecting a bomb? Read to find out.
The diagrams are clear and lovely. Apparently, they don't use double slit experiments too much anymore. They use interferometers, and the author goes into super extreme detail on them. It's funny, there are actually some new developments about the Diosi-Penrose theory, and I was reading that exact part of the book right when the article popped up on my phone. Naughty, naughty Google. But also, what a coincidence.
Recommend. 5 stars for the thought-provoking info.
The diagrams are clear and lovely. Apparently, they don't use double slit experiments too much anymore. They use interferometers, and the author goes into super extreme detail on them. It's funny, there are actually some new developments about the Diosi-Penrose theory, and I was reading that exact part of the book right when the article popped up on my phone. Naughty, naughty Google. But also, what a coincidence.
Recommend. 5 stars for the thought-provoking info.
May 29, 2019
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, natch.
June 2, 2019
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 usually discussed in popular science books. The short book starts almost where the famous Bohr/Einstein linked sagas end.
Bohm’s pilot wave, Elliott’s many worlds, and two other possible interpretations are explained in a way that makes it easy for readers to understand where they differ against each other and from the Copenhagen interpretation. More remarkably, the author wonderfully explains various complicated experiments involving Mach-Zehnder Interferometer, including Wheeler’s Delayed Choice and various Quantum Eraser varieties. While many of these topics are covered in other popular books, Mr. Ananthaswamy is able to shine the light on them in a new way in almost every single section of the book.
A must-read for anyone interested in quantum spookiness for decades to come.
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 usually discussed in popular science books. The short book starts almost where the famous Bohr/Einstein linked sagas end.
Bohm’s pilot wave, Elliott’s many worlds, and two other possible interpretations are explained in a way that makes it easy for readers to understand where they differ against each other and from the Copenhagen interpretation. More remarkably, the author wonderfully explains various complicated experiments involving Mach-Zehnder Interferometer, including Wheeler’s Delayed Choice and various Quantum Eraser varieties. While many of these topics are covered in other popular books, Mr. Ananthaswamy is able to shine the light on them in a new way in almost every single section of the book.
A must-read for anyone interested in quantum spookiness for decades to come.
October 31, 2018
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."
"I will not describe it in terms of an analogy with something familiar. I’ll simply describe it."
December 26, 2018
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.
May 31, 2023
"Through Two Doors at Once" by Anil Ananthaswamy is a captivating exploration of one of the most mind-bending aspects of modern physics: quantum mechanics. With a blend of scientific rigor, historical context, and personal narratives, Ananthaswamy takes readers on a fascinating journey through the concept of the double-slit experiment and its implications for our understanding of reality. This book is a must-read for anyone curious about the strange and perplexing world of quantum physics.
Ananthaswamy begins by delving into the historical background of the double-slit experiment, tracing its roots back to the early 19th century and the work of Thomas Young. He explains how Young's discovery of the interference pattern generated by light passing through two slits laid the foundation for our current understanding of wave-particle duality.
The author skillfully introduces key figures in the field of quantum mechanics, such as Max Planck, Albert Einstein, Niels Bohr, and Richard Feynman, who all contributed to unraveling the mysteries of quantum reality. Ananthaswamy presents their groundbreaking theories and experiments in a clear and accessible manner, making complex concepts comprehensible to readers with varying levels of scientific knowledge.
One of the strengths of "Through Two Doors at Once" is Ananthaswamy's ability to interweave scientific explanations with captivating personal stories. He takes readers to laboratories and research institutions around the world, introducing them to the scientists at the forefront of quantum research. Through their experiences, we gain a deeper understanding of the challenges, uncertainties, and excitement that accompany the study of quantum mechanics.
Ananthaswamy adeptly navigates through the various interpretations of quantum mechanics, from the Copenhagen interpretation to the many-worlds interpretation and beyond. He raises thought-provoking questions about the nature of reality and the role of the observer in shaping it. The author highlights the ongoing debates within the scientific community, offering readers a glimpse into the profound philosophical implications of quantum mechanics.
What sets this book apart is the author's commitment to making quantum mechanics relatable and relevant to everyday life. Ananthaswamy draws connections between quantum phenomena and the macroscopic world, exploring topics such as quantum computing, quantum cryptography, and the possibility of quantum effects playing a role in biological systems. By bridging the gap between the abstract and the concrete, he makes quantum mechanics accessible to a broader audience.
The book also delves into the challenges and limitations of conducting experiments in the quantum realm. Ananthaswamy explores the delicate balance between maintaining the delicate coherence of quantum systems and the unavoidable influence of the environment. He sheds light on the technological advancements and experimental techniques that have allowed scientists to probe the boundaries of quantum reality and expand our understanding of the universe.
Ananthaswamy's writing style is engaging and thought-provoking. He effortlessly combines scientific explanations with captivating anecdotes, ensuring that readers remain engrossed throughout the book. His passion for the subject matter shines through, and his enthusiasm is infectious. The author's ability to distill complex concepts into understandable terms is commendable, making this book accessible to both scientific enthusiasts and general readers.
One of the few shortcomings of "Through Two Doors at Once" is the occasional repetition of certain concepts and experiments. While repetition can be beneficial to reinforce understanding, some readers may find it slightly tedious. Nevertheless, this minor flaw does not detract significantly from the overall quality of the book.
Ananthaswamy successfully manages to evoke a sense of wonder and awe about the bizarre world of quantum mechanics. He skillfully navigates the treacherous terrain of the subject, striking a balance between scientific accuracy and engaging storytelling. The author's genuine curiosity and admiration for the subject matter permeate every page, inviting readers to join him on a captivating intellectual journey.
"Through Two Doors at Once: The Elegant Experiment That Captures the Enigma of Our Quantum Reality" is a book that challenges our intuitions, expands our imagination, and invites us to ponder the profound mysteries of the universe. Anil Ananthaswamy's masterful storytelling, combined with his deep understanding of quantum mechanics, makes this book an exceptional and thought-provoking read. Whether you are a seasoned physicist or simply curious about the nature of reality, this book will take you on an intellectual adventure that will leave you questioning the very fabric of our existence.
Ananthaswamy begins by delving into the historical background of the double-slit experiment, tracing its roots back to the early 19th century and the work of Thomas Young. He explains how Young's discovery of the interference pattern generated by light passing through two slits laid the foundation for our current understanding of wave-particle duality.
The author skillfully introduces key figures in the field of quantum mechanics, such as Max Planck, Albert Einstein, Niels Bohr, and Richard Feynman, who all contributed to unraveling the mysteries of quantum reality. Ananthaswamy presents their groundbreaking theories and experiments in a clear and accessible manner, making complex concepts comprehensible to readers with varying levels of scientific knowledge.
One of the strengths of "Through Two Doors at Once" is Ananthaswamy's ability to interweave scientific explanations with captivating personal stories. He takes readers to laboratories and research institutions around the world, introducing them to the scientists at the forefront of quantum research. Through their experiences, we gain a deeper understanding of the challenges, uncertainties, and excitement that accompany the study of quantum mechanics.
Ananthaswamy adeptly navigates through the various interpretations of quantum mechanics, from the Copenhagen interpretation to the many-worlds interpretation and beyond. He raises thought-provoking questions about the nature of reality and the role of the observer in shaping it. The author highlights the ongoing debates within the scientific community, offering readers a glimpse into the profound philosophical implications of quantum mechanics.
What sets this book apart is the author's commitment to making quantum mechanics relatable and relevant to everyday life. Ananthaswamy draws connections between quantum phenomena and the macroscopic world, exploring topics such as quantum computing, quantum cryptography, and the possibility of quantum effects playing a role in biological systems. By bridging the gap between the abstract and the concrete, he makes quantum mechanics accessible to a broader audience.
The book also delves into the challenges and limitations of conducting experiments in the quantum realm. Ananthaswamy explores the delicate balance between maintaining the delicate coherence of quantum systems and the unavoidable influence of the environment. He sheds light on the technological advancements and experimental techniques that have allowed scientists to probe the boundaries of quantum reality and expand our understanding of the universe.
Ananthaswamy's writing style is engaging and thought-provoking. He effortlessly combines scientific explanations with captivating anecdotes, ensuring that readers remain engrossed throughout the book. His passion for the subject matter shines through, and his enthusiasm is infectious. The author's ability to distill complex concepts into understandable terms is commendable, making this book accessible to both scientific enthusiasts and general readers.
One of the few shortcomings of "Through Two Doors at Once" is the occasional repetition of certain concepts and experiments. While repetition can be beneficial to reinforce understanding, some readers may find it slightly tedious. Nevertheless, this minor flaw does not detract significantly from the overall quality of the book.
Ananthaswamy successfully manages to evoke a sense of wonder and awe about the bizarre world of quantum mechanics. He skillfully navigates the treacherous terrain of the subject, striking a balance between scientific accuracy and engaging storytelling. The author's genuine curiosity and admiration for the subject matter permeate every page, inviting readers to join him on a captivating intellectual journey.
"Through Two Doors at Once: The Elegant Experiment That Captures the Enigma of Our Quantum Reality" is a book that challenges our intuitions, expands our imagination, and invites us to ponder the profound mysteries of the universe. Anil Ananthaswamy's masterful storytelling, combined with his deep understanding of quantum mechanics, makes this book an exceptional and thought-provoking read. Whether you are a seasoned physicist or simply curious about the nature of reality, this book will take you on an intellectual adventure that will leave you questioning the very fabric of our existence.
September 20, 2020
Every few years, I like to read a book about quantum theory to keep up to date with the science. The only problem is that I am not really very good at understanding formulas or technical terminology. Still, Anil Ananthaswamy's Through Two Doors at Once: The Elegant Experiment That Captures the Enigma of Our Quantum Reality showed me that physicists are still puzzling their heads over the nano-world of quantum mechanics.
What this book does is discuss the theory with respect to the "two-slit experiment" to determine what happens when light or even individual photons behave most strangely when they are confronted with an opaque barrier into which two or more slits have been cut.
I was able to follow much of the book's descriptions, perhaps as much as 50-60% Even with my limited ability, I found the book fascinating. It takes a chronological organization as new discoveries were made over a hundred year period.
What this book does is discuss the theory with respect to the "two-slit experiment" to determine what happens when light or even individual photons behave most strangely when they are confronted with an opaque barrier into which two or more slits have been cut.
I was able to follow much of the book's descriptions, perhaps as much as 50-60% Even with my limited ability, I found the book fascinating. It takes a chronological organization as new discoveries were made over a hundred year period.
January 18, 2019
In another world, I gave this book 5 stars.
February 14, 2023
This was a captivating story from start to finish.
Unlike a number of other books that discuss the theoretical (often veering into philosophical) aspects of modern physics, this one is pleasantly grounded in experimental observation (the "double-slit experiment" to be precise).
Towards the end, I wish I could have read more about experimental tests for the Bohmian view of the universe and the Many Worlds hypothesis, but I guess the lack of ideas here is more a reflection of the current state of fundamental physics, and not a shortcoming of the book itself.
Unlike a number of other books that discuss the theoretical (often veering into philosophical) aspects of modern physics, this one is pleasantly grounded in experimental observation (the "double-slit experiment" to be precise).
Towards the end, I wish I could have read more about experimental tests for the Bohmian view of the universe and the Many Worlds hypothesis, but I guess the lack of ideas here is more a reflection of the current state of fundamental physics, and not a shortcoming of the book itself.
March 19, 2019
Hell of a book. 10/10 would recommend.
August 19, 2018
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 mentioned in reference to the "wave-particle" duality of light. The best science teachers might even shoot a laser pointer through some diffraction gratings to demonstrate interference. Now, that's all fine as far as it goes, but there is so much more to this experiment and a modern understanding of quantum mechanics to just stop there. These experiments are the perfect opportunity to teach students that fundamental questions remain and that, with the right mindset and training, they could join the conversation and that it does not take genius to partake. Genius has been a part of this story to be sure, but at this point the full set of issues are readily described and understandable by the willing. If better answers to quantum mechanics are out there, they will be found by dedication, collaboration, and inspiration. The days of the loan genius solving complex problems is past.
Ananthaswamy's writing is clear and concise throughout. Like most popular science books, numbered footnotes are exchanged for text-based references. Yes, not seeing those damn little numbers may improve readability, but I'm the type of reader who likes to know exactly when something is being reference. Diagrams are employed occasionally and so the science can be, at times, rigorous for a popular science treatment. There were times when more detail, even if just as an appendix, was called for but this is a minor point of personal preference on may part. Strongly recommended for the quantum curious.
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 mentioned in reference to the "wave-particle" duality of light. The best science teachers might even shoot a laser pointer through some diffraction gratings to demonstrate interference. Now, that's all fine as far as it goes, but there is so much more to this experiment and a modern understanding of quantum mechanics to just stop there. These experiments are the perfect opportunity to teach students that fundamental questions remain and that, with the right mindset and training, they could join the conversation and that it does not take genius to partake. Genius has been a part of this story to be sure, but at this point the full set of issues are readily described and understandable by the willing. If better answers to quantum mechanics are out there, they will be found by dedication, collaboration, and inspiration. The days of the loan genius solving complex problems is past.
Ananthaswamy's writing is clear and concise throughout. Like most popular science books, numbered footnotes are exchanged for text-based references. Yes, not seeing those damn little numbers may improve readability, but I'm the type of reader who likes to know exactly when something is being reference. Diagrams are employed occasionally and so the science can be, at times, rigorous for a popular science treatment. There were times when more detail, even if just as an appendix, was called for but this is a minor point of personal preference on may part. Strongly recommended for the quantum curious.
August 5, 2019
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 at quantum mechanics through the double slit experiment (pun intended).
October 5, 2018
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.
March 13, 2019
Started off with a bang - wonderful delineation of the original thought experiment. Unfortunately it then dragged on, didn't love it enough to finish.
March 18, 2024
rtc later
October 10, 2025
This is a five-star popular synthesis of the most prominent interpretations of quantum mechanics.
For each interpretation, the author relies on variations of the double slit experiment to explain the mechanics. He not only uses plain and clear language, but worked with a technical illustrator to elegantly describe the quantum experiments. Some are very convoluted; one even involves a multi-million dollar mirror thousands of times smaller than a grain of sand. If anything, this book showed me the fascinating world of experimental quantum mechanics, which employs the most imaginative physicists I have come across. The engineering and ingenuity in some of these experiments is jaw-dropping.
The author also interviews every experimentalist and theorist, from Roger Penrose to Chris Fuchs, quoting them directly. Each chapter is about 40 pages and is dedicated to one specific interpretation, and its accompanying experiments (some interpretations, like MWI or QBism have no experiments; these are saved for the end).
I would recommend this book over Adam Becker's "What Is Real?" which ended up being a history of the EPR paper, and a scathing attack on Bohr and the Copenhagen interpretation. Becker is obviously a proponent of MWI, which he forces in the end. Not exactly an objective overview of interpretations, but I digress.
P.S. If you have read What Is Real? and the appendix, think of Two Doors as a masterful extrapolation of the appendix.
For each interpretation, the author relies on variations of the double slit experiment to explain the mechanics. He not only uses plain and clear language, but worked with a technical illustrator to elegantly describe the quantum experiments. Some are very convoluted; one even involves a multi-million dollar mirror thousands of times smaller than a grain of sand. If anything, this book showed me the fascinating world of experimental quantum mechanics, which employs the most imaginative physicists I have come across. The engineering and ingenuity in some of these experiments is jaw-dropping.
The author also interviews every experimentalist and theorist, from Roger Penrose to Chris Fuchs, quoting them directly. Each chapter is about 40 pages and is dedicated to one specific interpretation, and its accompanying experiments (some interpretations, like MWI or QBism have no experiments; these are saved for the end).
I would recommend this book over Adam Becker's "What Is Real?" which ended up being a history of the EPR paper, and a scathing attack on Bohr and the Copenhagen interpretation. Becker is obviously a proponent of MWI, which he forces in the end. Not exactly an objective overview of interpretations, but I digress.
P.S. If you have read What Is Real? and the appendix, think of Two Doors as a masterful extrapolation of the appendix.
January 13, 2019
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 overwhelmed me. I felt like most of these concepts are best explained interactively in a classroom setting and even then it is debatable how much of it can be grasped without the necessary math. Overall, I learned quite a few high level things about QM that I didn't know previously but my one take away is that I understand QM even less than I thought I did and I used to think I didn't understand it at all :)
September 19, 2020
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 ONE wave. One century later, in 1909, Taylor did a similar experiment with two small holes (double-slit) creating a diffraction pattern from TWO waves. From the 1960s, physicists started using electron beams and biprisms instead of slits in much more complex setups including two islands and satellites. This book compiles the history of how this striking experiment has been evolving in the last three centuries to unveil the wave-particle nature of light and to study the nondeterminism of Nature anticipated by Quantum Mechanics.
January 11, 2019
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 merits a re-read.
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 merits a re-read.
March 5, 2019
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
December 6, 2020
I really like a concise, broad-ranging book that gives not only a good overview of an area of interest but does it with concise writing. Ananthaswamy has created just such a work and covers many, many aspects of the two-slit experiment. An enjoyable, educational read.
July 24, 2021
An amazing read. It is not all that well-written and a few concepts—including, annoyingly, the uncertainty principle—are not explained in enough detail, but it is unputdownable on strength of subject matter alone
January 27, 2021
Very clear discussion on two-slit, with follow-on discussion of theories.
Yes, it took me four months to finish reading - not a page-turner.
I enjoyed Anil's writing.
Yes, it took me four months to finish reading - not a page-turner.
I enjoyed Anil's writing.
March 29, 2024
Started out being clear on understandable then took off to never never land in an exponential way. Maybe I'm just not smart enough to follow. Learned so new stuff but what a struggle.
June 21, 2025
a very good book on the complexities of quantum physics and how the greatest minds have struggle to decipher its mysteries
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