A very well-written account of the human endeavor to understand what quantum phenomena really mean. In my opinion, this is the most accessible account to a layperson trying to get a sense of the weirdness of quantum physics. And while the title of the book might make it sound like the book is narrow in scope, it in fact is anything but! ( )

Very good description of various interpretations of quantum mechanics. Well written with clear explanations of complex phenomena. ( )

“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 Ananthaswam

“What does it mean to say that the wavefunction collapses? There’s an even more basic question staring at us from within the formalism: Is the wavefunction real? Does it have - as philosophers like to say - ‘ontological’ reality?”

In “Through Two Doors at Once - The Elegant Experiment That Captures the Enigma of Our Quantum Reality” by Anil Ananthaswam

“Is the wavefunction ontic (meaning it is something) or is it epistemic (in that the wavefunction represents our knowledge about something); is the wavefunction objective or subjective?”

In “Through Two Doors at Once - The Elegant Experiment That Captures the Enigma of Our Quantum Reality” by Anil Ananthaswam

“In Bohmian mechanics, particles and their trajectories exist independent of observation, whereas in standard quantum mechanics [in the Copenhagen Interpretation] the act of observation creates reality.”

In “Through Two Doors at Once - The Elegant Experiment That Captures the Enigma of Our Quantum Reality” by Anil Ananthaswam

“Tests of Bell’s inequality clearly show that the quantum world is nonlocal [i.e., [not meeting the inequality].”

In “Through Two Doors at Once - The Elegant Experiment That Captures the Enigma of Our Quantum Reality” by Anil Ananthaswam

“In Bohmian mechanics, everything is a particle and a wave.”

In “Through Two Doors at Once - The Elegant Experiment That Captures the Enigma of Our Quantum Reality” by Anil Ananthaswam

The real underlying problem of seeking photon structure lies in the initial assumptions of the Standard Model. It is assumed that the photon is energy, and yet, there is no explanation for how energy can become a thing. The photon is electron angular momentum that has been inverted and shot out away from the atom at the velocity, c. Also, it is not realized by mainstream physics that the electron IS Planck's constant. In other words, Planck's constant is not just a convenience constant; it is the complete quantification of a single electron. Further still, subatomic particles are quantum angular momenta. Thus, the photon is equal to the electron times the speed, c, or phtn = h * c.

In the Standard Model, photons quantify as packets of energy equal to h * freq. But this is jumping ahead of the process. The photon is equal to h * c, and light is equal to phtn * freq. Light is the production of a steady stream of photons at a specific frequency.

So we have h = Planck's constant = electron;
phtn = h * c; and
ligt = phtn * freq.

When the angular momenta from light reaches a target, the angular momentum is absorbed and inverts back to the angular momentum of an electron. The result is that energy is received at the target...

enrg = ligt / c

This works out the same as h * freq, but the mechanics are different from what the Standard Model tells us is happening. With an incorrect understanding of angular momentum, photons, and light, and with the wrong quantification of the processes, the experiments are designed incorrectly and everything looks weird to the scientists.

The story of how good methodical science occurs was great in the book. The rubbish philosophy and basic fallacies less so. We have removed a few models but still can't say anything about whether the universe is real or non-real, deterministic or random only that at the moment a statistical approach works best. Imagine a sociologist arguing that human behaviour is not real (deterministic) when what they really mean is that it's too complicated to represent in any other way then statistically.

Human behaviour is implicate order established by interior response to external stimuli and it is hard coded, w/the semantic basis the language/behavior/emotional-energy of the family/culture of origin...and it's all learned through induction and mimicry, supposedly humans, like plants can only do what they have been programmed to do....they are as rigid as a spiraling vine in their attempts to achieve their goals and interpretations....cognitive psychology is a step forward. Humans cannot change their internal program except through drastic intervention....they can change their external behavior but not usually the underlying hard coded sensory interpretation of skeins of sensory information. David Bohm implied that the clockwork of physics was multidimensional, that you couldn't separate out the individual pieces so much as you could wave at them as a crowd and say these "guys" are involved in this set of actions/consequences... that doesn't mean that the clock doesn't have gears...just that the shape of the clock works is hard to change....but with enough ooomph it can change/morph....and that the actual clock movement is constrained by its physicality and yet it's electrons may be shared by conducting surfaces of metals in contact....and the force distributed throughout the mechanism implications? there are multiple intersecting "realities" in this reality that comprise a set known relationships but they bleed into each other a bit, quanta are the liquid blood. My point is specifically that the multiple interpretations of quantum mechanics means the philosophical question of whether the world is deterministic or not is still unsolved. By neglecting pilot wave theory due to its impracticalities is reasonable concluding that the world is fundamental random is not. All reasonable alternatives world need to be discarded not just a few fringe models.

I don't believe that "consciousness" has any special status, or is even well defined, but, whatever it might be, it would seem to require substantial size/complexity to be accepted as such, making the experiment effectively impossible to perform. But even assuming you somehow send a "conscious" entity through a double slit, then what? Do you ask it if it felt weird to go through two slits at once? And what does the answer establish? I don't get it, really, even as a Gedanken-experiment.

Ananthaswamy goes into this history in detail, and also discusses the fluid physical analogy to the double slit experiment. The fact that this physical analogy has not been replicated yet is in no way indicative of Bohm's interpretation being falsified -- that much is clear. Conversely, if those experiments are replicated in a way that shows interference it would be nice support for the general mechanisms proposed by Bohm and Hiley -- though not definitive.

Also, for context, I should probably mention that Bohmian QM is seeing a groundswell of support and in some unofficial polling of physicists and philosophers it seems to perhaps be vying for the #3 spot in terms of popularity behind Copenhagen and MWI. Ananthaswamy gives it second billing in his book after raising all the ways, in some detail, that the Copenhagen interpretation doesn't make sense (and never made sense). It seems to me that today most people equate pilot wave theory with Bohmian mechanics, and in general I think this is harmless, but it's not correct.

Bottom-line: Consciousness shouldn't effect anything; only the objects centre of mass is in a superposition state so there should be no difference in the internal degrees of freedom (which would affect consciousness). If you could see/feel/hear anything to determine where you are then the superposition would break down, but this is no different from the decoherence effecting an electronic in a superposition of multiple places, interactions with the wider environment leads to decoherence. Hence you could be in a complete vacuum floating in a box and in a superposition of being in this box on earth and the other side of the universe and you wouldn't notice the difference. ( )

"The double-slit experiment doesn't merely embody wave-particle duality ...: it incorporates entanglement too." (p 108) So the book is not nearly as overly narrow as the title would suggest. E.g., delayed-choice quantum erasure, weak measurements (in investigating Bohmian trajectories), and Penrose's idea of gravity-induced wavefunction collapse are all ably and interestingly reported on. Most of the coverage of non-Copenhagen psi-epistemic (but realist) interpretations consists of 11 pages on QBism oddly positioned inside the chapter on the (psi-ontic) many-worlds interpretation. "[O]ur understanding of the quantum world is still up for grabs." (p 262)