Is It Possible to Detect a Parallel Universe?

Diagram of the multiverse with two localization angles which may be used to pinpoint parallel universes within it. Might it be possible to conduct an experiment to demonstrate the influence of one such parallel universe?


Perhaps, in these tempestuous days, it is comforting to speculate that somewhere in the multiverse a parallel universe exists with another Earth in which there is no threat of global warming, alternative fuels provide most of the energy, the population is below carrying capacity and has all its needs met, and oh yes....politicians can conduct civil debates and the government always works on behalf of all citizens.

Perhaps such a place exists, but before such ruminations can be taken seriously, it would behoove us to first at least demonstrate that a parallel universe can be even remotely detected from within the confines of our own. Before considering such experiments - a bit of background.

Note that the "parallel universes" being considered here I regard as actual, separable PHYSICAL cosmi - and likely incepted from the selfsame primordial vacuum state (via cosmic inflation) as our own universe. Thus, an actual primordial vacuum - not a human observer or consciousness "making observational choices" (as in the case of the Hugh Everett 'Many worlds' interpretation of quantum theory)  is the source of the real parallel universes. Thus, all putative parallel universes plausibly emerged from the primordial vacuum the way ours did, e.g. from the Big Bang.

Regarding inflation, most current standard theories propose inflation starting at about  10^-35 s  and doubling over a period of anywhere from 10^-43 to 10^-35 s after the initial inception. Estimates are that at least 85 such 'doublings' would be required to arrive at the phase where entropy rather than field resident energy dominates. The initial size (radius) of our universe would have been likely less than a proton's - maybe 1 fermi (fm) or 10^-15 m, by the time the doubling process began. By the time it ended (after 90 'doublings') it would have been around 1.25 x 10¹²  m. This is roughly eight times the distance of Earth from the Sun. In effect, the role of inflation is to give cosmic expansion a huge head start or boost, without which our universe would be much smaller. Other parallel universes emerging around the same time might have been larger or smaller depending upon their specific values for their fundamental physical constants (e.g. alpha, the "fine structure constant", h - the Planck constant, G, and eta the permittivity of free space).


In the graphic, I show an "idealized multiverse" replete with parallel universes, each occupying longitudinal geodesics specified under a coordinate φ, and separated by uniform angular measure Θ from adjacent universes. The whole represents a 5-dimensional manifold in a toroidal topology. The topological space of the hypertoroid cosmos can therefore be represented by the global state space, a product of absolute hypertorus coordinate time (Θ) and 'all-space'(φ):GL = Θ X φ


Now, I repeat,  this is an idealized model which assumes that N-cosmi were incepted at equal intervals of time - as manifested by the equal spacing in Θ. In principle, we don't know a priori how "close" in complex time another parallel universe may be to our own. When one uses the assumption of "equal time intervals" between inceptions in our idealized multiverse, one isn't stating what those times are, and so they could be minuscule - and the smallest time unit imaginable is the unit tau, τ. (About 10^-43  s, and note Θ = f(τ).)

If we specify such an exact parallel universe time displacement we might be able to show how one parallel universe can be "mapped" topologically onto an adjacent one. As an example, let two parallel universes be distinguished by a 1-τ difference in fundamental time parameter, viz. [1 + 2τ] and [1 + 3τ], then we would require for connection, a mapping such that:

(Universe 'A'): f:X -> X = f(Θ,φ) = (Θ, 2φ)
(Universe 'B'): f:X -> X = f(Θ,φ) = (Θ, 3φ)


which means the absolute coordinate φ is mapped onto itself 2 times for [Universe A] and mapped onto itself 3 times for [Universe B]. Clearly, there’ll be coincidences for which: f(Θ,2φ) = f(Θ,3φ) wherein the two universes will 'interweave' a number of times.

For example, such interweaving will occur when φ = π/2 in [A] and φ = π/3 in [B]. The total set or system of multiple points obtained in this way is called a Synchronous temporal matrix. The distinguishing feature of this matrix is that once a single point is encountered, it is probable that others will as well. If one hyperspace transformation can occur linking parallel universes, A and B, then conceivably more such transformations can occur, linking A and C, D and E etc.

What if both absolute toroidal coordinates (Θ,φ) map into themselves the same number of times? Say, something like:


f:X -> = f(Θ, φ) = (2Θ, 2φ): Universe A


f:X -> = f(Θ, φ) = (3Θ, 3φ): Universe B


For example, given the previous conditions for coordinate φ, now let 2Θ = 3Θ for discrete values of Θ (e.g. 2π). For all multiples of 2π, the same toroidal cosmos will be experienced - if the absolute time coordinates are equal (e.g. π/2 = φ in A, and π/3 = φ in B) then we will have: Universe A = Universe B.

What does this equality mean? I conjecture that it implies a briefly inter-phased chaotic state prevails in both A and B where the fundamental physical constants are not fixed (in a future blog I will appeal to quantum chaos to describe this). For all intents and purposes it is as if a "portal" of sorts exists between them, though that doesn't mean it'd be accessible to humans. We say that there exists "an interpenetration of different parallel universes" but not necessarily entailing transfer of bodies from one to the other. Note that though the physical state spaces (e.g. with constants h, G, e/m, etc. )may be alike, they can still differ in dimensionality! And we cannot disregard fractal dimensionality.

IF one has this condition, THEN it is feasible that the (David) Deutsch experiment (See: The Fabric of Reality) to detect the interphasing of a parallel universe can be carried out, and the penetration of our universe by a parallel one validated.

In his book(pp. 38-47), Deutsch adopts the setup (Fig. 2-4) of a monochromatic light beam that passes through successive screens with single holes.  The image presented on the screen is a central bright spot with darker penumbra around it. With a two slit pattern for the screens (p. 41) the experiment becomes more interesting in that successive barriers to generate the patterns engenders what Deutsch calls  "shadow photons".

He acknowledges (p. 45) that "tangible" (i.e. measurable) photons are grounded in our tangible, current universe, but also that shadow photons can be thought of as collectively coming from a parallel universe.  He then clarifies this in mind-blowing fashion (p. 45):

"For it turns out that the shadow particles are partititoned among themselves in exactly the same way as the universe of tangible particles is partitioned from them. In other words, they do not form a single, homogeneous parallel universe vastly larger than the tangible one, but rather a huge number of parallel universes, each similar in composition to the tangible one, and each obeying the same laws of physics, but differing in that the particles are in different positions in each universe."

In other words, using the graphic I've shown, we would need multiple ordered pair angles (Θ, φ)  to actually lead to an incomprehensible number, thereby denoting all the shadow photons in one of Deutsch's experiments. But the existence of this multiplicity is what Deutsch uses to justify the term "multiverse" with which I concur. A final challenge to be met, is - I think - reconciling the physical multiverse with the (Hugh Everett III)  'Many worlds' interpretation of QM. I believe this requires using separate wave functions for each inflation-based parallel universe but exactly how each of these would be described is left to future QM workers. (They'd also need to ponder how 'many worlds' can be revamped if each wave state also coincides with a genuine, inflation-generated parallel universe. Also: Is the wave function a wholly physical representation (analogous to David Bohm's real de Broglie waves) , a statistical artifact or a combination of each?)

In the meantime, we've lots to ponder, including whether unknown to us sporadic interpenetrations can occur, say between a 'Universe A' and 'Universe B' and what effects they might have in our real world - say if our universe is denoted B. What physical factors might lead to such interpenetration or interphasing? Can any anomalous terrestrial events - like deja vu- which physicist Michio Kaku has speculated might occur in specific or unusual cases and not be merely memory short circuits -  arise from "flipping between universes? Perhaps before we go there we need to nail down the properties of these "shadow particles" more rigorously first!

Qbism and why Quantum Physicists Hate It

Consider standard quantum mechanics QM (for which the Copenhagen Interpretation applies) and operators are in one-to-one correspondence with the closed subspaces of the Hilbert space, H. Then if P is a projection, its range is closed, and any closed subspace is the range of a unique projection. If u is any unit vector, then  P= [ Pu]²   is the expected value of the corresponding observable in the state represented by u. Since this is {0,1}- (binary) valued, we can interpret this as the probability that a measurement of the observable will produce the "affirmative" answer 1. In particular, the affirmative answer will have probability 1 if and only if Pu = u; that is, u lies in the range of P.

Now in the QBist or Quantum Bayesian view, this is not so. The quantum state assignments are relative to the one who makes them. So if I as a quantum Bayesian assert that: P = [ Pu]²  is the expected value of the corresponding observable in the state represented by u = 0 and the result is {0,0}, then P = 0.
Thus as N. David Mermin recently observed (Physics Today, July, p. 8):

“QBism eliminates the notorious measurement problem ….an agent unproblematically changes her probability assignments discontinuously whenever new experiences lead her to change her beliefs. It is just the same for her quantum state assignments. The change in either case is not in the physical system the agent is considering. Rather, it is in the quantum state the agent chooses by which to encapsulate her expectations.”

In other words, a large component of subjectivity enters the picture. But this is initiated, as Mermin points out, by the very choice of Bayesian probabilities ab initio. To fix ideas, the typical quantum physicist has a confirmed “frequentist” concept of probability. Hence, a probability is determined by the frequency with which event E appears in some ensemble K of events, all of which have been identically prepared in the same system.

For example, consider a system of ten coins, each of which is equally weighted, balanced to yield- for ten separate tosses:

H H T H T H H T T T

Then out of this ensemble of ten fair tosses, T appears as many times as H which is 5, so

P = E/ K = 5/ 10 = 0.5

Thus, the objective observer will assign a probability of P = 50% to a single event embodying any such coin toss and this will reflect the observer’s belief the event will occur at least half the time.

On the other hand, for the Bayesian the probability is not inherent in a similar system of events but is projected via different agents who may have different beliefs based on pre-supposition. Say Agent X has the pre-supposition a particular series of coin tosses is weighted toward tails to appear, for whatever reason, then his expectation will be: P(T) = 0.6 perhaps.

As Mermin points out (ibid.):

“This personalist Bayesian view of probability is widely held, though not by many physicists”

Of course, this implies a definite opposition between physics and other fields which employ Bayesian statistics.

Now, in formal quantum mechanics, arrival of states, probabilities is contingent on information, knowledge. For example, knowledge may be obtained using an Aspect-type device such (as depicted below) which acts to disperse the individual atomic "magnets" (net-spin atoms) and send them in pairs (always in pairs) to D1 and D2 simultaneously. The question is, what spin is detected by each detector at the instant of observation?:



D1 (+½ ) <-------------[D]------------->(- ½ )D2



The knowledge or information arrived at is correlations or anti-correlations, for the spin of an atom, say helium, captured at detectors D1 or D2.

If a  ½ spin appears simultaneously we have correlation, otherwise anti-correlation.

Prior to the observation (actual detection), neither spin value can be known according to the Heisenberg Uncertainty Principle of Quantum Mechanics. That is, while the atomic magnets are in transit - from device to either detector - there is no definite information concerning which spin is going where. The reason has to do with what is called the superposition of states. To fix ideas, consider the whole atomic magnet in the device, before being ejected. If it’s a helium atom, then there’ll be one up spin and one down spin and we can write for simplicity:

U = å _i {(ups)i + (downs)i}

The obscurantist claim that the outcome "depends on perspective" is rubbish, since it is the observation that determines the outcome, and there is only one.

In the orthodox (and most conservative) interpretation of quantum theory, there can be no separation of observed (e.g. spin) state until an observation or measurement is made. Until that instant (of detection) the states are in a superposition, as described above. There’s nothing mysterious or strange about this as it follows entirely from the mathematics. More importantly, the fact of superposition imposes on all quantum phenomena an inescapable ‘black box’. In other words, no information other than statistical can be extracted before observation.

The late physicist Heinz Pagels, for example, has referred (in his excellent book, The Cosmic Code) to quantum measurement theory as an ‘information theory’ and noted the entire quantum world is embedded into what we observers can know about it. Obviously such knowledge is obtainable exclusively from observational or experiment results. Since only one apparatus is used, like I've shown there are no "differing perspectives" only one - at the instant of observation.

However, in QBism or quantum Bayesianism this gets chucked: Keep the set up for the experiment as shown and change observers for each sequence of say N trials. QBism asserts that each switch introduces a different probable outcome based on each observer’s belief about the system and how he makes state assignments.

Worse, in QBism there’a a bifurcation between the world –universe in which an agent or observer lives and her experience of it. This disconcerting aspect arises, according to Mermin:

“From a failure to realize that like probabilities, like quantum states, like experience itself….the split belongs to the observer.”

Each has its own split. Worse, an uncontrolled complementarity of experience enters with respect to any other observers. If “Judy” has experiences and observations that are macroscopic (i.e. related to the large scale world of planets, stars etc.), “Roy” will experience microscopic reality (the world of atoms, electrons and Higgs bosons!) To quote Mermin:

“Each split is between an object (the world) and a subject (an agent’s irreducible awareness of his or her own experience):

Mermin also makes the point, which I tend to agree with, that “ambiguities only arise if one fails to acknowledge that the splits reside not in the objective world but at the boundaries between that world and the experiences of the various agents who use quantum mechanics.”

Fair enough, but a couple questions: 1) Does this mean that the ‘Many worlds’ interpretation is now kaput? And 2) Does QBism indicate an objective difference between the microtubules of agents, with said entities evidently tied to consciousness and hence “irreducible awareness” ?

At least QBism does take care of one riddle, first posed by Einstein: Can a quantum wavefunction be collapsed by the observations of a mouse?

QBism answers ‘NO!’ since – according to Mermin – “the mouse lacks the mental facility to use quantum mechanics to update its state assignments on the basis of its subsequent experience?”

Hmmmmmm…But what if it’s a genetically engineered mouse, with the DNA of a human like Einstein spliced into its own?