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The Many Hidden Worlds of Quantum Mechanics
In a field known for startling ideas, the Many-Worlds Interpretation (MWI) of quantum mechanics may take the prize. It holds that parallel to our own world are a large number of other universes, almost identical to ours but with small variations. Copies of each of us inhabit a myriad of these worlds. But they are not us exactly; they share our past history, but they are different people who have unique futures. Although these realms are invisible and can’t communicate with each other, prominent physicists are convinced they must exist.
The Many Hidden Worlds of Quantum Mechanics is about why we should take the Many-Worlds Interpretation seriously, as arguably the best explanation of quantum mechanics, the science of matter and energy at the atomic and subatomic scales. In 24 fascinating lectures, Professor Sean Carroll of Johns Hopkins University guides listeners through the history, reasoning, and implications of this bold idea. He also covers alternate theories to Many-Worlds and unresolved questions in fundamental physics, making the course a thorough introduction to the current state of this exciting field.
Starting with classical physics, Professor Carroll explains how quantum theory overturned traditional ideas about matter and energy in the early 20th century. A consensus soon formed around a framework called the Copenhagen Interpretation, which rejected speculation about what was “really happening.” The Many-Worlds Interpretation in the 1950s was a reaction against this view, proposing that we take the basic equation of quantum mechanics seriously and go where it leads. It turns out it leads to Many-Worlds.
The course also covers quantum computing, quantum gravity, the resolution of quantum paradoxes, and speculation about whether human consciousness plays a central role in quantum experiments (Many-Worlds argues it doesn’t). Even die-hard skeptics of Many-Worlds will learn much from these lectures and will have their beliefs tested by a theory that is both mind-boggling and mathematically elegant.
The Many Hidden Worlds of Quantum Mechanics is about why we should take the Many-Worlds Interpretation seriously, as arguably the best explanation of quantum mechanics, the science of matter and energy at the atomic and subatomic scales. In 24 fascinating lectures, Professor Sean Carroll of Johns Hopkins University guides listeners through the history, reasoning, and implications of this bold idea. He also covers alternate theories to Many-Worlds and unresolved questions in fundamental physics, making the course a thorough introduction to the current state of this exciting field.
Starting with classical physics, Professor Carroll explains how quantum theory overturned traditional ideas about matter and energy in the early 20th century. A consensus soon formed around a framework called the Copenhagen Interpretation, which rejected speculation about what was “really happening.” The Many-Worlds Interpretation in the 1950s was a reaction against this view, proposing that we take the basic equation of quantum mechanics seriously and go where it leads. It turns out it leads to Many-Worlds.
The course also covers quantum computing, quantum gravity, the resolution of quantum paradoxes, and speculation about whether human consciousness plays a central role in quantum experiments (Many-Worlds argues it doesn’t). Even die-hard skeptics of Many-Worlds will learn much from these lectures and will have their beliefs tested by a theory that is both mind-boggling and mathematically elegant.
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Published November 24, 2023
About the author
Sean Carroll
28 books2,450 followersSean Carroll is a physicist and philosopher at Johns Hopkins University. He received his Ph.D. from Harvard in 1993. His research focuses on spacetime, quantum mechanics, complexity, and emergence. His book The Particle at the End of the Universe won the prestigious Winton Prize for Science Books in 2013. Carroll lives in Baltimore with his wife, writer Jennifer Ouellette.
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Displaying 1 - 7 of 7 reviews
May 13, 2024
Largely discussed is the many-worlds interpretation (MWI) of quantum mechanics which states it holds a parallel to our own world and therein exists a vast number of other universes---practically identical to the one we are in now albeit with small variances. Apparently there are copies of us living in these other worlds. Our copies are not exact yet remain similar because they share our past history. Different people and futures. These worlds are invisible and can’t communicate with each other.
"You do not cause the wave function to branch by making a decision."
---Sean Carroll
"You do not cause the wave function to branch by making a decision."
---Sean Carroll
This entire review has been hidden because of spoilers.
May 5, 2024
Sean Carroll's course on quantum mechanics from The Great Courses is genuinely extraordinary. He explains complex topics with amazing clarity, providing a definitive yet balanced view that primarily champions the many-worlds interpretation (MWI) while giving fair treatment to other interpretations. As in all his works, the professor’s passion for MWI shines through, making a compelling case for its elegance and explanatory power. The best parts are the sections on alternative theories, presented fairly and adequately.
While I deeply enjoy the MWI defense, I find myself drawn to alternative explanations that might resolve the mysteries of the quantum realm without needing a constantly multiplying multitude of universes. My current line of thought is admittedly speculative and without any technical rigor – but at least something that sits better with me is the rest of this review as my takeaways. It relies on the often-overlooked concept of “recoherence” and its implications for our understanding of quantum phenomena.
My view effectively focuses on the dynamic interplay of decoherence and recoherence. Imagine fundamental particles possessing intrinsic properties, such as spin, represented by a "fuzzy pin." This pin has a definite orientation along one axis, signifying a decohered state for that specific property, while remaining fuzzy and indeterminate in all other directions—a superposition of possibilities waiting to be realized.
This fuzzy pin persists in its state until an "interaction" occurs, causing a perturbation that disrupts its current orientation and establishes a new axis of decoherence. Imagine a gentle nudge causing the pin to tilt, changing its alignment axis while the fuzziness now encompasses the previously definite direction. This dynamic process reflects the ever-evolving nature of quantum systems as they interact with their environment.
The crucial question then becomes: what triggers this "interaction" and subsequent shift in decoherence? Two main possibilities emerge:
a) Collective Influence: Similar to the pilot wave theory, the combined force of nearby wave functions, particularly within macroscopic objects where countless particles interact, creates a perturbation that nudges the fuzzy pin onto a new axis. This collective "push" from the environment influences the particle's state, causing it to decohere along a specific direction based on the net effect of surrounding influences.
b) Localized Interactions: Alternatively, the perturbation could arise from individual interactions between particles when they come within a highly close proximity, almost colliding. This suggests that decoherence is a more localized phenomenon occurring at the micro-level during close encounters between particles. The probability of such close encounters increases significantly within macroscopic objects due to the sheer number of particles involved, leading to a higher likelihood of decoherence along a specific axis relevant to the measurement context.
This refined perspective aligns with elements of both pilot wave theory and other interpretations that emphasize the role of interactions in shaping quantum behavior. It suggests that decoherence is not a one-time event but rather a dynamic process where particles continuously shift between definite and indeterminate states based on their interactions with the environment. The fuzzy pin analogy captures this fluidity, with its axis of decoherence constantly adapting to the influences it encounters.
This interpretation, which ties with what we observe in sciences elsewhere, is not just a mere speculation. It may contain hidden variables or sub-theories, or alternatively, it could be one that should be falsifiable fairly quickly in all various forms, providing a solid foundation for further exploration.
Back to the course, it is a valuable resource for anyone interested in the field.
While I deeply enjoy the MWI defense, I find myself drawn to alternative explanations that might resolve the mysteries of the quantum realm without needing a constantly multiplying multitude of universes. My current line of thought is admittedly speculative and without any technical rigor – but at least something that sits better with me is the rest of this review as my takeaways. It relies on the often-overlooked concept of “recoherence” and its implications for our understanding of quantum phenomena.
My view effectively focuses on the dynamic interplay of decoherence and recoherence. Imagine fundamental particles possessing intrinsic properties, such as spin, represented by a "fuzzy pin." This pin has a definite orientation along one axis, signifying a decohered state for that specific property, while remaining fuzzy and indeterminate in all other directions—a superposition of possibilities waiting to be realized.
This fuzzy pin persists in its state until an "interaction" occurs, causing a perturbation that disrupts its current orientation and establishes a new axis of decoherence. Imagine a gentle nudge causing the pin to tilt, changing its alignment axis while the fuzziness now encompasses the previously definite direction. This dynamic process reflects the ever-evolving nature of quantum systems as they interact with their environment.
The crucial question then becomes: what triggers this "interaction" and subsequent shift in decoherence? Two main possibilities emerge:
a) Collective Influence: Similar to the pilot wave theory, the combined force of nearby wave functions, particularly within macroscopic objects where countless particles interact, creates a perturbation that nudges the fuzzy pin onto a new axis. This collective "push" from the environment influences the particle's state, causing it to decohere along a specific direction based on the net effect of surrounding influences.
b) Localized Interactions: Alternatively, the perturbation could arise from individual interactions between particles when they come within a highly close proximity, almost colliding. This suggests that decoherence is a more localized phenomenon occurring at the micro-level during close encounters between particles. The probability of such close encounters increases significantly within macroscopic objects due to the sheer number of particles involved, leading to a higher likelihood of decoherence along a specific axis relevant to the measurement context.
This refined perspective aligns with elements of both pilot wave theory and other interpretations that emphasize the role of interactions in shaping quantum behavior. It suggests that decoherence is not a one-time event but rather a dynamic process where particles continuously shift between definite and indeterminate states based on their interactions with the environment. The fuzzy pin analogy captures this fluidity, with its axis of decoherence constantly adapting to the influences it encounters.
This interpretation, which ties with what we observe in sciences elsewhere, is not just a mere speculation. It may contain hidden variables or sub-theories, or alternatively, it could be one that should be falsifiable fairly quickly in all various forms, providing a solid foundation for further exploration.
Back to the course, it is a valuable resource for anyone interested in the field.
April 2, 2024
The Many Hidden Worlds of Quantum Mechanics" by Sean Carroll serves as an intricate exploration of quantum mechanics, approached with Carroll's commendable humility and expertise. While Carroll advocates for the many-worlds interpretation, presenting thought-provoking arguments, readers may find themselves contemplating simpler alternatives to this complex quantum conundrum. Regardless, the book is a valuable contribution to the field, inviting both assent and thoughtful challenge, and it stands as a testament to the ongoing, fascinating dialogue surrounding the foundations of quantum physics.
Reflecting on this, the book does more than just educate; it stimulates critical thinking and encourages the pursuit of simpler, perhaps more elegant theories in quantum mechanics that are yet to be discovered. It's a compelling read for those who enjoy rigorous scientific discourse wrapped in accessibility.
Reflecting on this, the book does more than just educate; it stimulates critical thinking and encourages the pursuit of simpler, perhaps more elegant theories in quantum mechanics that are yet to be discovered. It's a compelling read for those who enjoy rigorous scientific discourse wrapped in accessibility.
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June 24, 2024Great book, thought-provoking and enlightening. Are time and space emergent phenomena, i.e. not fundamental? At what point do worlds split, as posited by this theory?
Many interesting concepts elucidated which you might have heard of, but never had time to wrap your head around: quantum entanglement, decoherence, etc. Sean C. even spends some time on compatabilism, i.e. the tension between determinism and perceived free will as basis for morality.
Many interesting concepts elucidated which you might have heard of, but never had time to wrap your head around: quantum entanglement, decoherence, etc. Sean C. even spends some time on compatabilism, i.e. the tension between determinism and perceived free will as basis for morality.
May 27, 2024
As usual Sean Carroll delivers. While I don’t ascribe to the many worlds interpretation of quantum mechanics, there’s plenty of other fun stuff here. While Dr Carroll goes to some lengths to make this complex subject approachable, this is not a light treatment.
August 21, 2024
Fantastic overview of this particular branch of Quantum Physics by Professor Sean Carroll. It is does a great job at considering other branches and interpretations as well.
August 22, 2024
This was a great book as an introductory to Quantum Mechanics, and the Hidden Worlds theory. It is not so deep in the weeds of the science and math, that the subject is inapproachable. But it does go deep enough that you feel like you're learning something new, and have a general understanding of the history and current work being done in this area.
Displaying 1 - 7 of 7 reviews