Modern Issues in Foundations of Physics




September 26 will be arrival day, with an informal gathering and drinks in the evening from 8pm. 

Venue: h-bar, basement of Sherfield Building, Imperial College. Sherfield building is number 20 on this map.


Talks will take place on the weekend of September 27/28, lecture room: Huxley 311, Department of Physics,

Imperial College London. Huxley building is number 13 on this map.


The conference dinner will take place at the Rembrandt Hotel, 11 Thurloe Place, London SW7 2RS, on

Saturday, September 27, from 19:00. If you registered for the dinner, please pay £25 upon registration on

Saturday from 8:15 or during the coffee break at 10:45.



Schedule (minor changes still possible)



Friday, Sep 26








20:00—ca. 22:30

Informal gathering and drinks, h-bar, Sherfield Building, Imperial College

All pay for themselves




Saturday, Sep 27 – all talks in Huxley 311










Please pay £25 if you registered for the conference dinner





Michael Duff, “Yang-Mills origin of gravitational symmetries”



Peter Knight, “Quantum Rulers –  Joint Measurement of Non-commuting Variables and Observing Uncertainty Relations”



Registration, coffee/tea break

Please pay £25 if you registered for the conference dinner


Roger Penrose, “Twistor non-locality and EPR effects”



Julian Barbour, “Typical Universes and their Entropy”



Lunch break

South Kensington station area or Gloucester Road, all pay for themselves


Lee Smolin (via video link), “Time, causality and law in a cosmological context”



Carlo Rovelli, “Chris, here is a hope for a quantum gravity effect we might be able to see: Planck stars”



Coffee/tea break

16:00 talk by Tom Kibble (by invitation only)


Free time/museum?



Meeting back at Imperial, walking to restaurant


19:00—ca. 21:30

Conference dinner at Rembrandt hotel





Sunday, Sep 28 – all talks in Huxley 311









Sarben Sarkar, “Signatures of CPT violation in mesons and neutrinos”



Tim Palmer, “Bell's Conspiracy, Schrödinger's Black Cat and Global Invariant Sets”



Coffee/tea break



Andreas Döring, “Topos, Ou Topos? Some Progress and Some Partial Truths”



Renate Loll



Lunch break

South Kensington station area or Gloucester Road, all pay for themselves


Jonathan Halliwell, “Negative Probabilities, Fine's Theorem and Quantum Histories”



Coffee/tea break



Steve Weinstein, “Degrees of Freedom”



Stanley Deser (via video link), “Massive Gravities, or how I got tenure by destroying Isham's models”



Closing remarks by Chris








          Back to main




Julian Barbour, Oxford: Typical Universes and their Entropy


It is shown in ArXiv:1409.0917 (PRL 26/09/14; JB, T Koslowski, and F Mercati) that a gravitational

arrow of time arises solely by virtue of the law of gravity and does not require any special initial

condition. Building on the methods of that paper, we have created a framework of gravitational

statistical mechanics for dynamically closed universes. It allows us to define an entropy of the

universe and establish the nature of typical universes. I will explain the basic ideas and surprising

conclusions of our theory using the Newtonian N-body problem. General relativity shares the key

structural features that underlie N-body theory, so our results should extend to Einstein gravity.



Stanley Deser, Brandeis: Massive Gravities, or how I got tenure by destroying Isham's models



Andreas Döring, Erlangen: Topos, Ou Topos? Some Progress and Some Partial Truths


I will present aspects of my joint work with Chris between 2006 and 2011 on the topos approach to

the formulation of physical theories, emphasising how radically the topos approach departs from

established theories and theory-making. I will then present some recent developments and pose the

question: is there hope that this approach will actually lead to some progress in foundations, or will

topos-based physics stay a utopia?



Michael Duff, Imperial: Yang-Mills origin of gravitational symmetries


By regarding gravity as the convolution of left and right Yang-Mills theories, we derive in

linearised approximation the gravitational symmetries of general covariance, p-form gauge

invariance, local Lorentz invariance and local supersymmetry from the flat space Yang-Mills

symmetries of local gauge invariance and global super-Poincare. Turning to global symmetries

we give a division algebra R,C,H,O description of Yang-Mills with N(L/R) = 1,2,4,8 and hence, by

tensoring left and right multiplets, a Freudenthal magic square RR, CR, CC, HR, HC, HH, OR, OC,

OH, OO description of  N=N(L)+N(R) supergravity.



Jonathan Halliwell, Imperial: Negative Probabilities, Fine's Theorem and Quantum Histories


Many situations in quantum theory and other areas of physics lead to quasi-probabilities which

seem to be physically useful but can be negative. The interpretation of suchobjects is not at all clear.

We argue that quasi-probabilities naturally fall into two qualitatively different types, according to

whether their non-negative marginals can or cannot be matched to a non-negative probability. The

former type, which we call viable, are qualitatively similar to true probabilities, but the latter type,

which we call non-viable, may not have a sensible interpretation. Determining the existence of a

probability matching given marginals is a non-trivial question in general. In simple examples, Fine's

theorem indicates that inequalities of the Bell and CHSH type provide criteria for its existence. The

proof of Fine's theorem is briefly discussed. The results have consequences for the linear positivity

condition of Goldstein and Page in the context of the histories approach to quantum theory. Although

it is a very weak condition for the assignment of probabilities it fails in some important cases where

our results indicate that probabilities clearly exist.


This talk is based on the papers


J.J.Halliwell and J.M.Yearsley, Phys. Rev. A 87, 022114 (2013)

J.J.Halliwell, Phys. Lett. A 378, 2945 (2014).



Peter Knight, Imperial: Quantum Rulers – Joint Measurement of Non-commuting Variables and

Observing Uncertainty Relations



Renate Loll, Nijmegen: tba



Tim Palmer, Oxford: Bell's Conspiracy, Schrödinger's Black Cat and Global Invariant Sets


A locally causal hidden-variable theory of quantum physics need not be constrained by the Bell

inequalities if this theory also partially violates the measurement independence condition. However, such

violation can appear unphysical, with implausible conspiratorial correlations between the hidden-variables

of particles being measured and earlier determinants of instrumental settings. Motivated by global

properties of the state space geometry associated with certain nonlinear dynamical systems, a novel

explanation for such correlations is proposed. The explanation is based on the proposal that states of

physical reality lie precisely on a measure-zero dynamically invariant set in the state space of the universe:

the Cosmological Invariant Set Postulate. To illustrate the relevance of the concept of a global invariant set,

a simple analogy is considered where a massive object is propelled into a black hole depending on the decay

of a radioactive atom: if the global nature of the event horizon (a photonic invariant set) were not recognised,

this experiment might also suggest either implausible conspiracy or retrocausality between the atom's

supposed hidden variables and the size of the black hole at early times. A locally causal hidden-variable

theory constrained by the Cosmological Invariant Set Postulate can violate the CHSH inequality without

being conspiratorial, superdeterministic, fine-tuned or retrocausal, and the theory readily accommodates

the classical compatibilist notion of (experimenter) free will. Just as the application of global geometric

methods revolutionised our understanding of gravitational physics in the 1960s, here it is proposed that

global geometric methods in state space may fundamentally change our understanding of quantum physics

and, by promoting a more synergistic relationship between quantum physics and cosmology, lead to new

insights in the problem of unifying quantum and gravitational physics.



Roger Penrose, Oxford: Twistor non-locality and EPR effects


The twistor description of wavefunctions for individual massless particles is fundamentally non-local, being

given in terms of holomorphic 1st cohomology. This reflects a certain non-locality of individual quantum

particles. For n particles we have a twistor description in terms of holomorphic nth cohomology. The connection

between this and EPR effects will be explored.



Carlo Rovelli, Marseille: Chris, here is a hope for a quantum gravity effect we might be able to see: Planck stars


Where does the matter falling into a black hole go?  Quantum gravity allows it to bounce around the Planck

density (at a radius much larger than Planckian) and the hole might quantum tunnel into a white hole.  An

estimate of the tunnelling probability indicates that this is should happen before extensive Hawking

evaporation.  Primordial black holes might be exploding now, producing signals we might be able to detect.

If so, this could be an observable quantum gravitational phenomenon. measuring it would be the best manner

to celebrate Chris.



Sarben Sarkar, King’s College London: Signatures of CPT violation in mesons and neutrinos


Quantum gravity models based both on decoherence and string theory backgrounds are examined within

the context of experiments at  meson factories and leptogenesis (and resultant baryogenesis). The breaking

of CPT invariance is inherent in the proposals. Signatures in correlations of kaon pairs and oscillation

properties of Majorana neutrinos are discussed.



Lee Smolin, Perimeter Institute: Time, causality and law in a cosmological context



Steven Weinstein, Waterloo: Degrees of Freedom


The statistical independence assumption in Bell's theorem (a.k.a. measurement independence) can be thought

of as the requirement that all degrees of freedom are local degrees of freedom.  That is, there are no nonlocal

constraints.  This suggests the possibility that quantum correlations might actually arise from correlations in initial

data encoded in such constraints.   Such constraints, though unfamiliar to many, need not be arcane or exotic. 

I'll give three simple examples.






          Back to main