Panel Discussion Questions - Perimeter Institute for Theoretical Physics

Is causality necessary at the level of QG? I.e. could causality be emergent?
What new development in QM foundations will it take to change the methodological Zeitgeist of physics back to a more philosophical, Einsteinian style of practice?
Does the necessity of defining a "caring weight" establish the primacy of ethics in philosophy? (Serious question!)
Is this a question?
Where, in the derivation of Bell's theorem, does the causal arrow of time come in?
Thinking about evolution of laws, does it make sense to think about evolution of laws of logic itself? Or would logic be somehow eternally "static"? Why or why not?
Rodi Tumulka has an answer for how long a particle is in a barrier: It is given by Bohmian mechanics, but is not directly observable. Only inferred from theory. Bill Unruh has an answer to the same question that comes from his own theory: All particles spend exactly 7 seconds in barriers, but that amount of time is not directly observable.
Without independent observability, what makes one theory science and the other fantasy? Why are they both not just counting angels on the head of a needle?
Does the block world of relativity need to be supplemented with an account of why the present is special? If so, can this be done with the exclusively physical resources of the theory, that is, without appeal to consciousness as fundamental?
Which laws have to be broken to reconstruct standard time evolution if the universe is taken to be in a superposition of different energy states?
Suppose for the sake of argument that quantum theory is not fundamental (it is a first order, or equilibrium approximation to ...) and quantizing gravity is inappropriate. 1) Is there evidence for or against this? 2) What implications does this have for the problems discussed at this conference?
What is the most fundamental "law" of nature? (And by the way, what is a "law"?)
A stopped clock is right twice a day. How many times a day is a stopped quantum clock right?
What is the use* of distinguishing the block universe from the evolving state? Could not any conceivable theory be written in both ways? *Use ~ Meaning.
Is QT sufficiently radical with respect to time?
If the fundamental reality is a succession of moments of space, why do we observe relativity of simultaneity at scales where spacetime curvature is negligible?
Can Aephraim do an experiment that would prove to us that things really happen? Or could he alternatively prove to us that nothing actually happens?
It has been suggested by some that many people who adhere to the many worlds interpretation seem to like it so much that they would adhere to some form of it even without quantum mechanics. Think of David Lewis or Max Tegmark. In other words, MWI may be more a statement of psychology than physics. React.
Why is the two-state theory (interpretation) not retrocausal?
To Huw, Ken Wharton, and others. Why call it "RETRO-causality"? In Huw's model all the nodes are tied together: left and right as well as up and down. I.e. it seems he imagines a true block universe. *Causes* can be taken to go in every direction.
Do things happen? If so, in what sense? If not, in what sense?
Is it really possible to recover geometry through causal sets?
What is the wavefunction? An ontological, epistemological or nomological field? Could it be an approximation to or indication of a more fundamental dynamical theory of beables (or hidden variables)?
Could you comment on---or, preferably debate---the suitability of the string-theoretic framework for working on the various problems of time?
What is the relation between the Many Worlds arrow-of-time and the thermodynamic one?
It has been noted that there are not representatives of the Griffiths-Omnes-Gell-Mann-Hartle ideology of consistent histories. Does anyone want to take this opportunity to defend them? Alternatively rail on them?
How will time be different in 100,000,000,000 years?
With promising progress on the experimental side of quantum communication and quantum information, can quantum computers be seen as a reality in years/decades to come?
Emergence appears to allow different and even contradictory physical concepts. Eg. the Wheeler-DeWitt equation allows for the emergence of the concept of a "global" time (in terms of the history of the universe) and also for the emergent concept of the moving present time ("now"). Should there not be a program of research that incorporates different concepts as emergent in the one framework.
Is Penrose's "Before-the-Big-Bang" hypothesis crazy or not?
Is it possible to have a complete cosmological theory without explicitly accounting for the fact that the mathematical system is a *model*, so our capacity to create such a model is a property of the universe that is not contained within the model itself?
Lee, how does "Law" differ from "regularity" or "uniformity"? (Peirce's term.)
Is the concept of probabilistic theories broad enough? We gave up determinism, could we be forced to give up probabilities for something more general? If so, what?
In your favourite proposed solution to the problem of time, is it possible to ask if timelike lengths are discrete or continuous, or is this unspeakable?
Quantum Foundations often gets bad publicity due to mis-statements by some of its proponents. Does PI have a strategy to cope with this?
Is the problem of time that produces the mismatch between QM and GR really a "problem of time" in probability theory?
Huw Price said in his talk that he saw retro-causality as a way of MWI (many worlds) in interpreting QM. What's wrong with MWI from his perspective? What does retro-causality give us that is better?
What would be a good name for the point of view OPPOSING that of the "block universe" conception of nature?
Is our universe retrocausal? (at least in part)
In Samson Abramsky's talk we learned of the utility of thinking of entangled quantum states as "time evolutions" (completely positive maps). Does this mean (or indicate) that there is a good way of thinking of quantum states as evolutions in disguise?
In the canonical Hamiltonian theory of GR only conserved quantities are gauge invariant, i.e., observables. But the perihelion motion of Mercury has been observed, and it is not a conserved quantity. How to reconcile these statements?

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