Massey Lecture - Other location

Time, cosmology and quantum foundations

I argue that quantum mechanics cannot usefully  be extended to a theory of the whole universe, so the task of quantum foundations is to discover that cosmological theory which reduces to quantum mechanics when restricted to small subsystems of the universe.  I argue that that cosmological theory will be based on a global notion of physical time which implies the distinction between past, present and future is real and objective.  These motivate two examples of novel formulations of quantum theory: the real ensemble formulation and the principle of precedence.  Each may imply departur

Energy diffusion from relativistic spontaneous localization

We discuss energy diffusion due to spontaneous localization (SL) for a relativistically-fast moving particle. Based on evidence from relativistic extensions of SL we argue that non-relativistic SL should remain valid in the particle rest frame. This implies that calculations can be performed by transforming non relativistic results from the particle rest frame to the frame of the observer. We demonstrate this by considering a relativistic stream of non-interacting particles of cosmological origin and showing how their energy distribution evolves as they traverse the Universe.

Lecture Series presented by KPMG - The Origin of the Universe and the Arrow of Time

One of the most obvious facts about the universe is that the past is different from the future. We can turn an egg into an omelet, but can't turn an omelet into an egg. Physicists have codified this difference into the Second Law of Thermodynamics: the entropy of a closed system always increases with time. But why? The ultimate explanation is to be found in cosmology: special conditions in the early universe are responsible for the arrow of time.

Lecture Series presented by KPMG - Life, the Universe and Nothing: Life, and Science, in an Ever Expanding Universe

Over the last decade our picture of the universe has changed almost as much as it had in the preceding century. As a result, our picture of the future, both of the universe, and life within it, has dramatically altered as well. This talk will begin by reviewing the recent revolutionary developments in cosmology, and then address several fascinating questions that have arisen as a result of our discovery that the dominant energy of the universe resides in empty space: Can life be eternal in an eternally expanding universe,? Are the laws of physics tailored for the existence of life?

Q2C Wrap - Up

In this closing session, festival panelists will look back over the preceding ten days to review what we've learned about the Quantum, the Cosmos, and Ideas for the Future.

Detecting Modified Gravity in the Stars

Screened Scalar-Tensor gravity such as chameleon and symmetron theories allow order one deviations from General Relativity on large scales whilst satisfying all local solar-system constraints. A lot of recent work has therefore focused on searching for observational signatures of these

Axiverse Cosmology and the Energy Scale of Inflation

Ultra-light axions (m_a
I will also present preliminary results of constraints to this model using up-to-date cosmological observations, which verify the above picture. The parameter space is interesting to explore due to a strongly mass dependent covariance matrix, motivating comparisons between Metropolis-Hastings and nested sampling. Finally I discuss fine-tuning and naturalness in these models.

Transporting non-Gaussianity from sub- to super- horizon scales

The non-Gaussian statistics of
the primordial density perturbation have become a key test of the inflationary
scenario of the very early universe. Currently many techniques are used to
calculate the non-Gaussian signatures of a given model of inflation. In
particular, simple super-horizon techniques such as the deltaN formalism are
often used for models with more than one field, while more technical field
theory techniques, referred to as the In-In formalism, are typically used for

Spin-1/2 Heisenberg Antiferromagnet on the Kagome Lattice: a Z2 Spin Liquid with Fermionic Spinons

Motivated by recent numerical and experimental studies of the spin-1/2 Heisenberg antiferromagnet on kagome, we formulate a many-body model for fermionic spinons, which are just uncoupled spins. The spinons interact with an emergent U(1) gauge field and experience strong short-range attraction in the S=0 channel. The ground state of the model is generically a Z(2) liquid. We calculate the edge of the two-spinon continuum and compare the theory to the slave-fermion approach to the Heisenberg model.