(Back to the menu - click here.)





 Thursday, 20 April 2023

    Video-Recording for any system with MP4-support

   - Video.mp4  (ca. 516 Mb)

 15:15 – 16:30



                       "Explaining the simplicity of the cosmos"


                                                Neal Turok

                                                 (University of Edinburgh, UK)


Observations of the universe on very small and large scales have revealed a

surprising economy in its basic laws and structure. In contrast, our theories

have become increasingly complex and contrived, introducing many new

particles, fields and even dimensions of space which are, as yet, unobserved.

In this talk, I will outline a more economical and predictive program, aiming

to solve cosmology’s main puzzles using only the Standard Model including

neutrino masses and general relativity. Instead of postulating a period of

inflation before the hot big bang, we extrapolate the observed simple universe

all the way back to the singularity. Instead of adding new particles and forces,

we assume a minimal modification of the Standard Model which improves

the vacuum and preserves local scale symmetry. The symmetry ensures that

the hot plasma filling the early universe is insensitive to the size of the universe

as it shrinks to zero at the singularity. Mathematically, the singularity is replaced

by a kind of mirror. The simplest-yet proposed dark matter candidate -- a stable,

right handed neutrino – becomes viable, a possibility to be tested by galaxy surveys

in the next few years.  We calculate the gravitational entropy for realistic

cosmologies, with radiation, matter, lambda and space curvature.

We find that the entropy favours flat, homogeneous and isotropic universes like ours,

with a small positive cosmological constant. We compute the primordial fluctuations

which seeded the formation of galaxies and other structures in the universe, ab initio,

in terms of Standard Model couplings. Remarkably, subject to two key theoretical

assumptions, the amplitude and spectral tilt of these fluctuations agree with the

observed values, with no free parameters. In principle, all features of the standard

LambdaCDM model for cosmology are thereby explained in a highly predictive new

framework which does not require inflation. I'll review forthcoming observational

tests as well as remaining theoretical challenges.




Neil Turok (PhD at Imperial College London, 1983) is the Inaugural Higgs Chair of

Theoretical Physics at the University of Edinburgh. Before taking up the appointment

in Scotland, Turok was the director of the Perimeter institute in Canada from 2008 to

2019. Previously, he was Professor of Physics at Princeton University and Chair of

Mathematical Physics at the University of Cambridge.


Among his many honours, Turok was awarded Sloan and Packard Fellowships and

the James Clerk Maxwell medal of the Institute of Physics (UK).


In 2016 he was named the Gerald Whitrow Lecturer by the Royal Astronomical Society

and was also awarded the John Torrence Tate Medal for International Leadership

in Physics by the American Institute of Physics.


Born in South Africa, Turok founded the African Institute for Mathematical Sciences

(AIMS) in Cape Town in 2003. AIMS has since expanded to a network of six centres

– in South Africa, Senegal, Ghana, Cameroon, Tanzania, and Rwanda – and has

become Africa's most renowned institution for postgraduate training in mathematical



                              <<<<<<  Denna sida ändrades, den 13 juni 2024 kl.17:34:58    >>>>>>