- Organized by
Gregory Gabadadze, Ph.D.New York University
Eva Silverstein, Ph.D.Stanford University
Paul Steinhardt, Ph.D.Princeton University
Cumrun Vafa, Ph.D.Hollis Professor of Mathematicks and Natural Philosophy; Professor of Physics, Harvard University
Monday August 26, 2019
Participation is by invitation only. All participants must register.
The second annual meeting of the Origins of the Universe program will bring together four diverse groups of theoretical cosmologists and string theorists, each addressing the history of the universe in their own ways. The themes of the presentations and discussions will include inflationary dynamics and its observational probes, string cosmologies, bouncing and cyclic cosmologies, and other proposals for geodesically past-complete classical models.
THURSDAY, SEPTEMBER 26
8:30 AM CHECK-IN & BREAKFAST 9:30 AM Paul Steinhardt | A New Kind of Cycle Universe 10:30 AM BREAK 11:00 AM Anna Ijjas| The Virtues of Slow Contraction, and Other Perks of Bouncing 12:00 PM LUNCH 1:30 PM Eva Silverstein | de Sitter and Large Field Inflation in String Theory 2:30 PM BREAK 3:00 PM Raphael Flauger | On the Robustness of Inflation to Initial Conditions 4:00 PM BREAK 4:30 PM Guido D'Amico | The Analysis of BOSS data with the EFTofLSS 4:50 PM Victor Gorbenko | Holography and Correlation Functions in de Sitter 5:10 PM DAY ONE CONCLUDES
FRIDAY, SEPTEMBER 27
8:30 AM CHECK-IN & BREAKFAST 9:30 AM Frans Pretorius | Numerical Studies of Modified Gravity 10:10 AM BREAK 10:40 AM Cumrun Vafa | Swampland and Cosmology 11:40 PM LUNCH 12:40 PM Andrew Tolley 1:40 PM BREAK 1:50 PM David Pirtskhalava | Early and Late Time Cosmology Beyond GR 2:30 PM MEETING CONCLUDES
A New Kind of Cycle Universe
The talk will explain how combining intervals of slow contraction with a (non-singular) classical bounce naturally leads to a novel cyclic theory of the universe in which the Hubble parameter, energy density and temperature oscillate periodically, but the scale factor (and hence the size of the universe) grows by an exponential factor from one cycle to the next.
The Virtues of Slow Contraction, and Other Perks of Bouncing
In this talk, I will discuss the robustness of a slowly-contracting primordial epoch to initial conditions in realistic set-ups, using the full power of numerical general relativity. In addition, I will review recent progress on studying the generation of primordial perturbations as well as constructing smooth cosmological bounces.
de Sitter and Large Field Inflation in String Theory
In this talk I will start by reviewing models of accelerated expansion in string
theory (both existing ones and new examples under development), explaining the methodology behind the examples and their consistency. Most stress energy sources in string theory produce positive potential energy in four dimensions, with crucial and well-known negative contributions appearing at intermediate orders in the expansion in weak coupling and large curvature radius. Localized sources contribute calculable forces in a well-defined approximation scheme, whose nature depends on the strength of the gradients in the extra dimensions. In existing models as well as new ones under development, fluxes also play a key role in stabilizing the shape of the internal geometry. These have a standard generalized form in string theory which depends on the axion fields of the theory, often resulting in large field inflation whose phenomenology depends on back reaction on the geometry which was calculated in the models. In addition to applying to early universe phenomenology, this structure led to a framework for quantum gravity in de Sitter spacetime obtained by uplifting the AdS/CFT correspondence. This dual description became significantly more complete in the past year via its relation to a generalization of the T Tbar deformation, as detailed in Gorbenko’s talk at this meeting.
On the Robustness of Inflation to Initial Conditions
Inflation was proposed as a solution to the horizon problem. It only provides a solution if inflation does not have a horizon problem itself. In this talk I will discuss recent analytic and numerical results about the robustness of inflation to inhomogeneities.
The Analysis of BOSS data with the EFTofLSS
We analyze the DR12 BOSS galaxy clustering data, using the EFTofLSS formalism. We assume ΛCDM, a fixed value of the baryon/dark-matter ratio, and of the tilt of the primordial power spectrum. After validating our technique against several sets of numerical simulations, we measure the primordial amplitude of the power spectrum, As , the abundance of matter, Ωm , and the Hubble parameter, H₀ , to about 12.4%, 3.0% and 2.9% respectively. We find ln(1010 As ) = 2.79 ± 0.12, Ωm = 0.309 ± 0.009, H₀ = 68.3 ± 2.0 km/(s Mpc) at 68% confidence level. Our results are a substantial qualitative and quantitative improvement with respect to former analyses.
Holography and Correlation Functions in de Sitter
I will briefly review the existing approaches to holography for cosmological spacetimes, focusing on the dS/dS correspondence. This method relates a gravitational theory in de Sitter space to a theory in de Sitter space of lower dimension, which, in particular, allows to benefit from several novel exact results obtained in lower-dimensional quantum field theories. I will then discuss the calculations of correlation functions in cosmology with the help of stochastic differential equations as well as some properties of the wave function of the universe that these calculations highlight.
Numerical Studies of Modified Gravity
In this talk, I will describe some of the challenges applying modified gravity theories to scenarios that are of interest to both testing general relativity with gravitational wave observations, and to early universe cosmology. The issues can be most pronounced in the dynamical, strong-field regime, where numerical solution methods are often required. As a case study, I will describe new results on gravitational collapse and black hole formation within Einstein-dilaton-Gauss-Bonnet gravity.
Swampland and Cosmology
I review some of the recent developments in the Swampland program and how it relates to cosmology. In particular I discuss how the H0 tension is reduced in the context of extensions of LCDM which are compatible with the Swampland criteria.
Early and Late Time Cosmology Beyond GR
I will review proposals that aspire to describe a geodesically complete classical theory of early universe, either interpolating to inflation or replacing inflation by alternative phases. I will also review how similar theories can describe the late time cosmic acceleration of the universe.
Forefronts of Gravitational Physics Workshop
Those who are attending the Forefronts of Gravitational Physics Workshop Sept 24-25, 2019 in Princeton should plan to arrive on Monday, September 23rd. Please make this selection when you register. Accommodations will be made for you in Princeton, and a shuttle will take participants to New York in the evening of September 25th.
Air and Train
Group AThe foundation will arrange and pay for all air and train travel to the conference for those in Group A. Please provide your travel specifications by clicking the registration link above. If you are unsure of your group, please refer to your invitation sent via email.
Group BThe foundation will cover hotel accommodations for those in Group B. Please provide your travel specifications by clicking the registration link above. If you are unsure of your group, please refer to your invitation sent via email.
Group CIndividuals in Group C will not receive travel or hotel support. Please register at the link above so we can capture your dietary requirements. If you are unsure of your group, please refer to your invitation sent via email.
Personal CarFor participants in Groups A and B driving to Manhattan, the Roger Hotel offers valet parking. Please note there are no in-and-out privileges when using the hotel’s garage, therefore it is encouraged that participants walk or take public transportation to the Simons Foundation.
Participants in Groups A & B who require accommodations are hosted by the foundation for a maximum of three nights at The Roger hotel. Any additional nights are at the attendee’s own expense.
The Roger New York
131 Madison Avenue
New York, NY 10016
(between 30th and 31st Streets)
To arrange accommodations, please register at the link above.
For driving directions to The Roger, please click here.