Adventures in Quantumland

Exploring Our Unseen Reality

Ruth E Kastner

• Publisher: WSPC (EUROPE)
• Year: 2019
• ISBN:
  9781786346438
• Topic: Scienze fisiche
• Subtopic: Teoria quantistica

This title is a self-contained follow-up to Understanding Our Unseen Reality: Solving Quantum Riddles (2015). Intended for the general reader but including more advanced material and an appendix of technical references for physics students and researchers, it reviews the basics of the transactional interpretation of quantum mechanics in its newer incarnation as a fully relativistic, realist interpretation of quantum theory, while embarking on further explorations of the implications of quantum theory. This interpretation is applied to new experiments and alleged 'paradoxes' that are found to be fully explicable once various misconceptions are identified.

There is currently much disagreement about the meaning of quantum theory, as well as confusion about the implications of various experiments such as 'weak measurements,' 'quantum eraser,' and delayed choice. This book provides a clear way forward, presenting new developments and elaborating a promising interpretational approach that has completely nullified earlier objections (such as the Maudlin objection). It also explains why some prominent competing interpretations, such as 'decoherence' in an Everettian ('Many Worlds') approach, do not work as advertised.

Adventures in Quantumland: Exploring Our Unseen Reality offers a fully relativistic interpretation of quantum mechanics with no discontinuity between non-relativistic and relativistic domains and shows how quantum theory allows for free will and for reconciliation of science and spiritual traditions.

Contents:

• Prologue
• About the Author
• Part I: Our Transactional Reality:
  • The Iceberg Revisited
  • The Transactional Interpretation
  • Observation and Measurement
  • The Spacetime Theater
  • Becoming and the Arrow of Time
  • Life and Free Will
  • Science and Spirit
  • Epilogue
  • Appendix: Behind the Magician's Curtain
• Part II: Selected Papers:
  • Quantifying Absorption in the Transactional Interpretation
  • On the Status of the Measurement Problem: Recalling the Relativistic Transactional Interpretation
  • Taking Heisenberg's Potentia Seriously
  • The Emergence of Space–Time: Transactions and Causal Sets
  • On Quantum Collapse as a Basis for the Second Law of Thermodynamics
  • Beyond Complementarity
  • Bound States as Fundamental Quantum Structures
  • Antimatter in the Direct-Action Theory of Fields
  • Haag's Theorem as a Reason to Reconsider Direct-Action Theories
  • 'Einselection' of Pointer Observables: The New H-Theorem?
  • The Born Rule and Free Will: Why Libertarian Agent-Causal Free Will is not 'Antiscientific'
• Index

Readership: Intended for the general reader but includes more advanced material and an appendix of technical references for physics students and researchers.Quantum Theory;Spacetime;Metaphysics;Free Will;Time0 Key Features:

• Offers a fully relativistic interpretation of quantum mechanics with no discontinuity between non-relativistic and relativistic domains
• Solves longstanding interpretational issues in a realist manner
• Shows how quantum theory is compatible with free will
• Debunks misleading and untenable claims about new experiments

Part I

Our Transactional Reality

Chapter 1

The Iceberg Revisited

‘Tell me, why do we require a trip to Mount Everest in order to be able to perceive one moment of reality? . . . I mean, is Mount Everest more “real” than New York? Isn’t New York “real?” I think if you could become fully aware of what existed in the cigar store next door to this restaurant, it would just blow your brains out!’ — Wally Shawn, My Dinner with Andre

1.1 The Lump in the Carpet

Imagine that a friend gives you a beautiful, hand-loomed carpet as a gift — a one-of-a-kind creation by a world-renowned craftsman. The only problem is, when you place it in your living room, you find it’s too big, and it pops up in lumps here and there. You are able to smooth out the main lump beneath your coffee table, but then you notice that a new lump has appeared next to the couch. When you smooth that one out, a lump mysteriously appears next to the bookcase. Try as you might, shifting and tugging, you just cannot find a position for the rug that doesn’t involve a lump popping up somewhere. Finally, you buy a new, solid TV cabinet, hide the lump under that, and call it good. It never occurs to you to put the carpet in a bigger room. Or perhaps that is the largest room in your house, and you don’t want to buy a new house just to properly fit your new carpet.

Metaphorically speaking, this is where the study of quantum theory has now stalled among most researchers (as of the time of writing of this book). The ‘carpet’ represents quantum theory, and the living room represents the ‘spacetime theater.’ The world described by quantum theory simply doesn’t fit in the ‘living room’ of the 3 + 1 dimensions of space and time (three dimensions of space and one dimension of time). This lack of fit is reflected in the mathematical form of the theory itself, and is evidenced by phenomena such as nonlocality and entanglement. ‘Entanglement’ means the intermingling of two quantum systems in such a way that the influence due to a measurement on one member of an entangled pair of quanta is communicated apparently instantaneously to the other, no matter how far away it is — the latter sort of influence is called ‘nonlocal.’ The fact that quantum objects do not seem to correspond to spacetime processes or events has been acknowledged by prominent quantum researcher Anton Zeilinger, who said in 2016:

. . . it appears that on the level of measurements of properties of members of an entangled ensemble, quantum physics is oblivious to space and time.

It appears that an understanding is possible via the notion of information. Information seen as the possibility of obtaining knowledge. Then quantum entanglement describes a situation where information exists about possible correlations between possible future results of possible future measurements without any information existing for the individual measurements. The latter explains quantum randomness, the first quantum entanglement. And both have significant consequences for our customary notions of causality.

It remains to be seen what the consequences are for our notions of space and time, or space-time for that matter. Space-time itself cannot be above or beyond such considerations. I suggest we need a new deep analysis of space-time, a conceptual analysis maybe analogous to the one done by the Viennese physicistphilosopher Ernst Mach who kicked Newton’s absolute space and absolute time from their throne. (Zeilinger, 2016)

In fact, the transactional picture (as developed by the present author) agrees with Zeilinger’s intuition that possibility is involved in arriving at a correct understanding of quantum theory. In particular, it proposes that this ‘information’ needs to be understood as physically real possibilities that are precursors to spacetime; this feature is discussed in more detail in later chapters. However, among those who believe that for something to be real, it must exist in spacetime, and that physical science can only describe things in spacetime, there is no way to really smooth out this figurative lump.

Efforts to smooth out the pesky ‘lump in the quantum theory carpet,’ which arises from clinging to the traditional idea that ‘real’ means ‘existing in spacetime,’ take various forms. For example, in a proposal by Hugh Everett (1957) that has become known as the ‘Many Worlds Interpretation,’ the proposed solution is to (metaphorically) consider your entire living room to be continually splitting.¹ In the so-called ‘de Broglie–Bohm’ theory, the lump is nailed down with the addition of so-called ‘hidden variables’ — specifically, hypothetical localized corpuscles whose existence doesn’t harmonize very well with relativity.² In the Copenhagen interpretation, due primarily to Niels Bohr, the lump is metaphorically shuttled back and forth so as to be out of sight of whoever is currently sitting in the living room. The currently predominant ‘decoherence’ approach metaphorically amounts to hiding the lump under the TV cabinet and calling it good (although, as of the writing of this book, some researchers are already expressing discontent with that approach, in view of its recognized inadequacies (for details, see Kastner (2014)).

If we want to get rid of the lump for good, we simply need a bigger living room — and we also need to unfold the carpet (yes, it’s actually twice as big as we originally thought). This book is about the interpretation that says ‘OK, let’s make room for what quantum theory has to tell us. Let’s unfold this carpet and move a few walls.’ In a previous work, Understanding Our Unseen Reality: Solving Quantum Riddles (UOUR for short), we’ve already done a bit of exploring of the full carpet and larger living room that results.

Metaphorically, the ‘unfolding’ is the recognition that there are ‘time-reversed’ states in the theory that represent real physical processes.³ These are strange to us because they seem to describe propagation of influences into the past, also known as retrocausation, which disagrees with our empirical experience. In fact, according to the interpretation proposed here, these time-reversed states do not literally propagate in spacetime (this subtle issue will be explored in more detail in subsequent chapters). They are disregarded in ‘mainstream’ interpretations as ‘unphysical’ — i.e., as only mathematical devices, elements of the recipe for calculating what we should expect to observe. But in fact, these strange time-reversed states are crucial to making physical sense of the process of ‘measurement,’ the major cause of the lump. The ‘living room enlargement’ is the recognition that quantum theory describes objects that are real, but that do not live in the relatively small living room of the 3 + 1 dimensions of spacetime. To their credit, some prominent researchers such as Zeilinger have now realized this, and are urging others to explore this expanded view of reality. This book continues that exploration.

1.2 More than Meets the Eye

In Understanding Our Unseen Reality: Solving Quantum Riddles (UOUR), we considered the idea that quantum theory is telling us about an aspect of reality that cannot be captured in the usual terms of facts and events that exist in space and time. Rather, quantum theory is telling us about specific forms of physical possibility that, in a definite mathematical sense, are ‘too big’ to fit into the four dimensions of spacetime. A rough metaphor is that of an iceberg, whose tip represents the 3 + 1 dimensions of spacetime, while the vast remaining bulk of the iceberg below the water (i.e., below the visible or empirical level) represents the very real, but hidden, quantum possibilities (Figure 1.1).

Figure 1.1. Spacetime is just the tip of the iceberg, while Quantumland lies hidden beneath.

This ‘underwater’ part of reality is quite real, and the components of this realm are those that obey the laws of quantum mechanics. Because it is not part of the spacetime realm, it behaves in strange ways, as expressed in the Heisenberg Uncertainty Principle (HUP). The HUP deals with observables — i.e., what we can indirectly observe of a quantum object, which really means what inferences we can make about its behavior (since we never see this directly). An ‘observable’ corresponds to a particular kind of property, such as momentum (quantity of motion) or position (location in space). Many observables, such as momentum and position, are mutually incompatible. This means (unlike in ordinary classical observations) that it makes a difference in what order they are measured: the results you get will differ depending on the order. A vivid example of this sort of thing is that the results will differ greatly depending on whether you (1) open the window and stick your head out or (2) stick your head out and then open the window!⁴ Quantum measurements are processes like this, and they very much affect the systems on which the processes are carried out. In addition, the HUP tells us that a quantum system such as an electron simply does not have a well-defined position if it has a precise momentum value, and vice versa. This lack of definition of one of more features of an object is called indeterminacy. It is much stronger than just saying that we can’t know what the value of position or momentum is: in a very real sense, the system does not have both properties well defined at any given instant of time.

The HUP is what quantifies this indeterminacy: not all of the properties that we usually think of as required for ‘physical reality,’ such as position and momentum, are determinate. Quantum objects thus have an ephemeral character that makes us uneasy if we expect reality to present itself in well-defined, determinate ways. The latter is the classical concept of reality, and in the previous book I argued that we need to broaden our concept of what counts as ‘reality’ in order to understand what quantum theory is telling us about the world.

Another unusual and surprising feature of the ‘underwater’ or behind-the-scenes quantum realm is that it can escape from some of the strictures of relativity, which apply only to the tip of the iceberg (the spacetime realm). Components of the quantum realm give rise to influences that seem to travel faster than light — this is the nonlocality mentioned above, which Einstein called ‘spooky action at a distance.’ In view of these peculiarities, physicists have long resisted the idea that quantum objects are physically real. This resistance is exemplified by both Niels Bohr and Albert Einstein, although their resistance took different forms. For Einstein, it was primarily due to his distaste for nonlocality, as he expressed in the phrase above; for Bohr it was primarily due to his insistence that ‘real’ implies ‘determinate’ (i.e., meaning always well-defined, and therefore able to be communicated using classical concepts). The resistance continues today in the plethora of interpretations that try to ‘save locality’ and ‘save determinacy’ by adding ‘hidden variables’ to the theory. Hidden variables represent hypothetical properties that are assumed to be always possessed by a quantum object, such as always-determinate positions (these are the ‘Bohmian corpuscles’). But these extra quantities are not in the mathematical quantum formalism itself, so they have to be added in ‘by hand’ — a move described by the Latin term ad hoc, meaning ‘for this situation.’ These efforts arise because of the ongoing expectation (which I argue needs to be relinquished) that reality must be classical in nature — i.e., that it must be both determinate and local, as captured by the phrase local realism. Underlying the desire to eliminate nonlocality and indeterminacy is the impression that these are supernatural notions — that they don’t adhere to what is assumed to be the scientific standard for a ‘natural’ account of reality, and therefore, like ghosts, should not be accepted as real.

However, it is useful to recall that there need not be a dichotomy of ‘natural’ vs. ‘supernatural’ phenomena. In fact, there is a third option: phenomena that seem to defy our expectations for what is real and explicable, but upon expansion of our concepts and tools of understanding, can in fact be understood in a scientifically responsible way. This third option is captured by the term ‘preternatural,’ which means ‘apparently inexplicable by natural means.’ It represents a ‘middle way’ of scientifically sound inquiry. We can understand quantum phenomena as preternatural: arising from something that can be scientifically understood, but which requires that we ‘think outside the box’ of our usual expectations and criteria for what counts as a ‘natural’ explanation of something real. In the following brief interlude, we’ll explore this idea of the preternatural and see what it might have to teach us about imaginatively exploring avenues of understanding on which we otherwise might be hesitant to embark.

1.3 The Haunting of Hill House . . . and Modern Physics?

I was reminded of the somewhat archaic, but very useful, term ‘preternatural’ introduced above while watching the classic 1963 horror flick The Haunting. In this film, a scientist decides to investigate Hill House, a nearly century-old mansion notorious for being cursed with untimely deaths and considered as unden...