Very few have taken the paper as a joke allowing to concretize in a humorous manner delicate and difficult and yet unresolved questions related to the notion of time. People with strong beliefs firmly based on text book wisdom about physics as it was in their youth are aggressively attacking ideas that the joke meant to concretize. Typical blog behavior of course.
There are three unconventional ideas involved which tend to be seen as sources of all the evil.
- The action defining quantum field theory could have imaginary part suppressing some histories (in this case those allowing a successful production of Higgs in laboratory).
- Action could possess space-time locality unlike actions of quantum field theories usually have.
- The idea of backward causation meaning that signals can propagate backward in time: here one should however specify what one exactly means with time and causation.
Since these unconventional ideas relate very closely to the basic distinctions between quantum TGD and standard approach, I will try to demonstrate that they are not a threat for the civilization.
Should we tolerate imaginary part and space-time non-locality of action?
The idea about imaginary part of action supressing some histories need not be crackpottish if properly formulated. There is also a good motivation for something like this: the basic difficulty of both quantum field theories and string model is that path integral is not well-defined mathematically.
- One could try to overcome the problem by adding an imaginary part to the action so that phase factor is replaced with a complex exponent and some histories are indeed supressed and one obtains a well-defined integral around minimum of the real part of the imaginary exponent of action (usually the extremal with a stationary phase defines the perturbationt theory). The loss of unitarity is the obvious objection.
- Unfortunately this is not enough. Space-time locality of quantum field theory implies infinities in n-point functions of the theory. So that there is order also for non-locality. The problem with non-locality is how to realize it in a non-ad-hoc manner.
It seems that a solution of problem generates new problems. These new problems are avoided in quantum TGD.
- Light-like 3-surfaces (or equivalently space-like 3-surfaces are taken as fundamental objects and the fundamental variational principle assigns to them unique 4-D space-time surface. This is nothing but quantum holography. Don't be afraid. This is a good thing;-).
- Path integral is replaced with a functional integral over 3-surfaces with the exponent of Kähler action for a preferred extremal (space-time surface) defining the analog of Gaussian. The infinite-dimensional integral over 3-surfaces is well defined since exponential suppression occurs and local divergences are absent since the counterpart of action depends in a non-local manner on 3-surface. This represent 20 years old layer of TGD.
- The loss of unitarity is not a catastrophe in zero energy ontology where S-matrix is replaced with M-matrix defined as a "complex square root" of the density matrix having S-matrix as a "multiplicative phase factor" so that quantum theory becomes "complex square root" of thermodynamics. Quantum field theory at non-zero temperature is a respected branch of theoretical physics and its TGD counterpart emerges at the level of fundamental formulation. This layer of TGD is about half decade old.
Should we tolerate backward causation?
I see nothing crackpottish even in the notion of backward causation. What is crackpottish or probably just a joke is to propose that this would explain why Higgs has not been discovered yet. As far as plausibility is considered this proposal brings to my mind the brane constructions meant to reproduce standard model symmetries (certainly not intended to be jokes)!
- In zero energy ontology physical states are replaced with zero energy states formed by entangled pairs of positive and negative energy states at opposite light-like boundaries of causal diamonds (CDs) defined as intersections of future and past directed light-cones. Zero energy ontology allows positive energy signals propagating to geometry future as well as negative energy signals propagating to geometric past. Negative energy signals justify the notion of backwards causation and it forms the corner stone of TGD inspired quantum biology and consciousness theory. It also resolves fundamental philosophical problems of theoretical physics posed by some innocent looking questions (What are the total conserved quantum numbers of the Universe and why are there values what they are?).
- When the time scale of observations is larger than the size of CD involved with the phenomenon studied, standard thermodynamics applies. If not, the signals propagating in both time directions are significant somewhat like in standard Feynman diagrammatics. The recent formulation of quantum TGD indeed supports the view that antimatter is in negative energy states near the opposite light-like boundary of CDs. This would conform completely with Feynman's view and explain the generation of matter antimatter asymmetry.
- The hierarchy of Planck constants - motivated by the mysteries of dark matter and dark energy plus intriguing observations suggesting quantum effects in both biology and astrophysics- leads to a generalization of 8-D imbedding space to a book like structure with pages partially characterized by the values of Planck constant. This hierarchy makes possible quantum coherence in arbitrary long scales so that there exist always sheets of the many-sheeted space-time at which second law cannot be applied at all or applies in both directions of geometric time. Biology would represent a basic example of this kind of situation.
- Quantum biology is one of the basic applications of quantum TGD and the basic mechanisms of intentional action, metabolism, and memory rely on backwards causation. One must of course make a clear distinction between geometric time and subjective time (identified as a sequence of quantum jumps) in order to avoid paradoxes. The precise articulation of this distinction in TGD framework has turned out to be extremely useful exercise and could be also seen as one of the motivations for TGD inspired theory of consciousness besides the challenge of making observer a genuine part of the physical system by introducing the notion of self.
- Most importantly, backwards causation has experimental support. Libet's paradoxical finding that neural activity precedes conscious decision finds in this framework a nice explanation without giving up free will. Phase conjugate laser beams provide the direct experimental evidence at the level of physics: for instance, they obey second law in reversed direction of geometric time: this has even technological application.
Since the generally accepted conceptual framework is lacking, theoretical physicists follow Wittgenstein's advice and prefer to be silent about the fascinating phenomena related to backwards causation. And about many other things too: it seems that the recent day theoretical physics is filled with taboos;-)).