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VERSION:2.0
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BEGIN:VEVENT
SUMMARY:The emergence of spacetime is governed by a quantum Mach's princip
le
DTSTART;VALUE=DATE-TIME:20230512T154500Z
DTEND;VALUE=DATE-TIME:20230512T163000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-651@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Lee Smolin (Perimeter Institute)\n"I describe a cand
idate for a fundamental physical theory called the causal theory of views.
This describes a world constructed by a continual creation of events\; w
here an event is a transition at which a small portion of the possible\nb
ecomes actual. I first recall older results which includes the emergence
of space and\, with space\, a non-relativistic N-body quantum dynamics.
I next describe recent progress on this model including\, in a different l
imit\, a formulation of a cut off quantum field theory\, which we describ
e in terms of an S-Matrix formulation of amplitudes. \n\nThe dynamics is
specified by an action principle consisting of a kinetic energy and potent
ial energy term. \nThe former are based on measures of how quickly compon
ents of causal change do so with respect to averaged notions. The potenti
al energy terms measure how much local moves alter an observer's ""view""
of the universe\, as seen from their perspective.\n\nThese results show th
at quantum dynamics is restored in an N to infinity limit. Measurable non
-linear corrections to quantum dynamics emerge to higher order in 1/sqrt{N
}. "\n\nhttps://events.perimeterinstitute.ca/event/39/contributions/651/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/651/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nonlocality in the causal set approach to quantum gravity
DTSTART;VALUE=DATE-TIME:20230511T180000Z
DTEND;VALUE=DATE-TIME:20230511T184500Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-645@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Fay Dowker (Imperial College London)\nThe nonlocalit
y of causal sets gives us hope of solving the cosmological constant puzzle
(``why is the universe so smooth\, big and old if there is only one scale
---the discreteness scale---in the theory?’’)\n\nOn the other hand loc
ality\, \, GR and local QFT\, must be recovered from quantum gravity in t
he continuum approximation at large scales\, which is a challenge. If we
are lucky though (like Goldilocks\, the universe gets the nonlocality ``ju
st right’’) nonlocality may be a rich source of phenomenology. Yasaman
Yazdi’s talk will be on cosmological models based on the nonlocality of
causal sets. I will give a couple of examples of more astrophysical pheno
menological models based on simple assumptions---randomness due to spaceti
me uncertainty and Lorentz invariance---and pose a research question: is t
here a model of ``quantum swerves’’?\n\nhttps://events.perimeterinstit
ute.ca/event/39/contributions/645/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/645/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Looking for Echoes from Quantum Black Holes
DTSTART;VALUE=DATE-TIME:20230511T134500Z
DTEND;VALUE=DATE-TIME:20230511T143000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-642@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Jahed Abedi (University of Stavanger)\nI present an
unprecedented template-based search for stimulated emission of Hawking rad
iation (or Boltzmann echoes) by combining the gravitational wave data from
65 binary black hole merger events observed by the LIGO/Virgo collaborati
on. With a careful Bayesian inference approach\, I found no statistically
significant evidence for this signal in either of the 3 Gravitational Wave
Transient Catalogs GWTC-1\, GWTC-2 and GWTC-3. However\, the data cannot
yet conclusively rule out the presence of Boltzmann echoes either\, with t
he Bayesian evidence ranging within 0.3-1.6 for most events\, and a common
(non-vanishing) echo amplitude for all mergers being disfavoured at only
2:5 odds. The only exception is GW190521\, the most massive and confidentl
y detected event ever observed\, which shows a positive evidence of 9.2 fo
r stimulated Hawking radiation. An optimal combination of posteriors yield
s an upper limit of A<0.42 (at 90% confidence level) for a universal echo
amplitude\, whereas A∼1 was predicted in the canonical model. The next g
eneration of gravitational wave detectors such as LISA\, Einstein Telescop
e\, and Cosmic Explorer can draw a definitive conclusion on the quantum na
ture of black hole horizons.\n\nhttps://events.perimeterinstitute.ca/event
/39/contributions/642/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/642/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Holographic Cosmology
DTSTART;VALUE=DATE-TIME:20230510T193000Z
DTEND;VALUE=DATE-TIME:20230510T201500Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-639@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Paul McFadden (Newcastle University)\nHolography has
profoundly transformed our understanding of quantum gravity in spacetimes
with asymptotic negative curvature. Its implications for cosmology are e
qually profound\, suggesting that time is emergent and that our universe h
as a dual description in terms of a three-dimensional quantum field theory
. This talk will outline key features of holographic cosmology\, from the
perspective it offers for the cosmic singularity to the strategies it pre
sents for computing cosmological observables. Recent results for the de S
itter wavefunction will be discussed and their interpretation in the langu
age of three-dimensional conformal field theory.\n\nhttps://events.perimet
erinstitute.ca/event/39/contributions/639/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/639/
END:VEVENT
BEGIN:VEVENT
SUMMARY:In Search of Lost Spacetime
DTSTART;VALUE=DATE-TIME:20230510T180000Z
DTEND;VALUE=DATE-TIME:20230510T190000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-638@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Chris Smeenk (Western University)\nThe classical spa
cetime manifold of general relativity disappears in quantum gravity\, with
different research programs suggesting a variety of alternatives in its p
lace. As an illustration of how philosophers might contribute to an interd
isciplinary project in quantum gravity\, I will give an overview of recent
philosophical debates regarding how classical spacetime "emerges." I wil
l criticize some philosophers as granting too much weight to the intuition
that a coherent physical theory must describe objects as located in space
and time. I will further argue\, based in part on historical episodes\,
that an account of emergence needs to recover the structural features of c
lassical GR responsible for its empirical success. This is more demanding
than it might at first appear\, although the details of recovery will dif
fer significantly among different approaches to quantum gravity.\n\nhttps:
//events.perimeterinstitute.ca/event/39/contributions/638/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/39/contributions/638/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum Superpositions of Black Holes
DTSTART;VALUE=DATE-TIME:20230510T154500Z
DTEND;VALUE=DATE-TIME:20230510T163000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-637@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Robert Mann (University of Waterloo)\nIf relativisti
c gravitation has a quantum description\, it must be meaningful to conside
r a spacetime metric in a genuine quantum superposition. Here I present a
new operational framework for studying “superpositions of spacetimes”
via model particle detectors. After presenting the general approach\, I
show how it can be applied to describe a spacetime generated by a BTZ bla
ck hole in a superposition of masses and how such detectors would respond.
The detector exhibits signatures of quantum-gravitational effects remini
scent of Bekenstein’s seminal conjecture concerning the quantized mass s
pectrum of black holes in quantum gravity. I provide further remarks in
distinguishing spacetime superpositions that are genuinely quantum-gravita
tional\, notably with reference to recent proposals to test gravitational
ly-induced entanglement\, and those in which a putative superposition can
be re-expressed in terms of dynamics on a single\, fixed spacetime backgro
und.\n\nhttps://events.perimeterinstitute.ca/event/39/contributions/637/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/637/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Where effective field theory fails: Windows into quantum gravity?
DTSTART;VALUE=DATE-TIME:20230509T134500Z
DTEND;VALUE=DATE-TIME:20230509T143000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-628@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Adam Koberinski (University of Pittsburgh)\nEffectiv
e field theory is a computationally powerful and flexible theoretical fram
ework\, finding application in many areas of physics. In particle physics\
, Weinberg’s folk theorem also promises that any theory that reproduces
the predictions of the Standard Model will\, at low energies\, look like a
n effective field theory. In one sense the power of this framework should
be a cause for pride in the progress of physics and discovery of real stru
ctural features of the world. But given the inability to fully unite quant
um theory and gravity into a consistent theoretical picture\, there is als
o cause for pessimism: indirect tests of candidate theories of quantum gra
vity will ultimately reduce to something like an effective field theory\,
undermining efforts to find low-energy windows into new physics. One way a
round this pessimism is to look at where and why effective field theory br
eaks down in current physical theories. I will point to familiar breakdown
s (the cosmological constant\, inflation\, the hierarchy problem)\, offeri
ng a take on what these breakdowns tell us about the shape of physics beyo
nd the Standard Model. Cracks in the wall of effective field theory allow
for a dim glimpse of what might lie beyond.\n\nhttps://events.perimeterins
titute.ca/event/39/contributions/628/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/628/
END:VEVENT
BEGIN:VEVENT
SUMMARY:What is the simplicity of the early universe trying to tell us?
DTSTART;VALUE=DATE-TIME:20230508T180000Z
DTEND;VALUE=DATE-TIME:20230508T184500Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-624@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Latham Boyle (Perimeter Institute)\n"After reviewing
some key hints and puzzles from the early\nuniverse\, I will introduce re
cent joint work with Neil Turok\nsuggesting a rigid and predictive new app
roach to addressing them.\n\nOur universe seems to be dominated by radiati
on at early times\, and positive vacuum energy at late times. Taking the
symmetry and analyticity properties of such a spacetime seriously leads to
a new formula for the gravitational entropy of our universe\, and a pictu
re in which the Big Bang may be regarded as a kind of mirror.\n\nI will ex
plain how this line of thought suggests new explanations for a number of o
bserved properties of the universe\, including: its homogeneity\, isotropy
and flatness\; the arrow of time (i.e. the fact that entropy increases *a
way* from the bang)\; several properties of the primordial perturbations\;
the nature of dark matter (which\, in this picture\, is a right-handed ne
utrino\, radiated from the early universe like Hawking radiation from a bl
ack hole)\; the origin of the\nprimordial perturbations\; and even the exi
stence of three generations of standard model fermions. I will discuss so
me observational predictions that will be tested in the coming decade\, an
d some key open questions."\n\nhttps://events.perimeterinstitute.ca/event/
39/contributions/624/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/624/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Physics with non-perturbative quantum gravity: the end of the Hawk
ing evaporation
DTSTART;VALUE=DATE-TIME:20230512T130000Z
DTEND;VALUE=DATE-TIME:20230512T134500Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-648@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Carlo Rovelli (Centre de Physique Théorique (CPT))\
nQuantum gravitational phenomena dominate the physics of a black hole in t
he past of a high curvature spacelike surface. Because of the backreaction
of the evaporation\, this surface crosses the horizon. I describe a rece
nt line of investigation on the possible evolution compatible with nonper
turbative quantum gravity\, and in particular I illustrate what can be pre
dicted using loop quantum gravity.\n\nhttps://events.perimeterinstitute.ca
/event/39/contributions/648/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/648/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Do First-Class Constraints Generate Gauge Transformations? A Geome
tric Perspective.
DTSTART;VALUE=DATE-TIME:20230510T150000Z
DTEND;VALUE=DATE-TIME:20230510T154500Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-636@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Clara Bradley (University of California\, Irvine)\nT
he constrained Hamiltonian formalism is the basis for canonical quantizati
on techniques. However\, there are disagreements surrounding the notion of
a gauge transformation in such a formalism. The standard definition of a
gauge transformation in the constrained Hamiltonian formalism traces back
to Dirac: a gauge transformation is a transformation generated by an arbit
rary combination of first-class constraints. On the basis of this definiti
on\, Dirac argued that one should extend the form of the Hamiltonian in or
der to include all of the gauge freedom. However\, Pitts (2014) argues tha
t in some cases\, a first-class constraint does not generate a gauge trans
formation\, but rather "a bad physical change". Similarly\, Pons (2005) ar
gues that Dirac's analysis of gauge transformations is "incomplete" and do
es not provide an account of the symmetries between solutions. Both author
s conclude that extending the Hamiltonian in the way suggested by Dirac is
unmotivated. If correct\, these arguments could have implications for oth
er issues in the foundations of the constrained Hamiltonian formalism\, in
cluding the Problem of Time. In this talk\, I use a geometric formulation
of the constrained Hamiltonian formalism to show that one can motivate the
extension to the Hamiltonian independently from consideration of the gaug
e transformations\, and I argue that this supports the standard definition
of a gauge transformation without falling prey to the criticisms of Pitts
(2014) and Pons (2005). Therefore\, in order to maintain that first-class
constraints do not generate gauge transformations\, one must reject the c
laim that the constrained Hamiltonian formalism is fully described by the
geometric picture\; I suggest two avenues for doing so.\n\nhttps://events.
perimeterinstitute.ca/event/39/contributions/636/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/636/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum Gravity and its connection to observations
DTSTART;VALUE=DATE-TIME:20230508T133000Z
DTEND;VALUE=DATE-TIME:20230508T141500Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-621@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Astrid Eichhorn (University of Southern Denmark)\nTo
make progress in developing a quantum theory of gravity\, we need to conn
ect candidate theories to observations. I will review ideas on connecting
quantum gravity to observations in particle physics\, to searches for dark
matter and to observations of black holes\, in particular with the (next-
generation) Event Horizon Telescope.\n\nhttps://events.perimeterinstitute.
ca/event/39/contributions/621/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/621/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Emergent Metric Space-Time from the BFSS Matrix Model
DTSTART;VALUE=DATE-TIME:20230509T130000Z
DTEND;VALUE=DATE-TIME:20230509T134500Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-627@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Robert Brandenberger (McGill University)\nEffective
field theory analysis are inadequate to describe the evolution of the very
early universe. I will describe an approach to obtain emergent time\, eme
rgent space\, an emergent metric and an emergent early universe cosmology
starting from the BFSS matrix model\, a proposed non-perturbative definiti
on of superstring theory. In this approach there is no cosmological consta
nt problem.\n\nhttps://events.perimeterinstitute.ca/event/39/contributions
/627/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/627/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Analogical reasoning in quantum gravity
DTSTART;VALUE=DATE-TIME:20230512T150000Z
DTEND;VALUE=DATE-TIME:20230512T154500Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-650@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Doreen Fraser (University of Waterloo)\nAnalogical r
easoning has a long and distinguished history as a method for making disco
veries in physics. I will discuss novel uses of formal analogies in twenti
eth century particle physics and condensed matter physics. I will then off
er some reflections on how methodological lessons from these cases could i
nform the use of analogies in discoveries related to quantum gravity.\n\nh
ttps://events.perimeterinstitute.ca/event/39/contributions/650/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/650/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Imaging Supermassive Black Holes and mapping spacetime
DTSTART;VALUE=DATE-TIME:20230508T141500Z
DTEND;VALUE=DATE-TIME:20230508T150000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-622@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Roman Gold (University of Southern Denmark)\nI will
give an overview of how the Event Horizon Telescope achieves its horizon s
cale science and what's to come. I will also review selected recent result
s from the Event Horizon Telescope both on Sgr A* and refined analysis of
M87*. A focus will be on analysis aspects that are relevant for any theory
/ model building along with a few examples. The presentation aims to prov
ide key conceptual aspects relevant to gravity experts who are new to VLBI
.\n\nhttps://events.perimeterinstitute.ca/event/39/contributions/622/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/622/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Echoes and Entropy of Quantum Black Holes
DTSTART;VALUE=DATE-TIME:20230511T130000Z
DTEND;VALUE=DATE-TIME:20230511T134500Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-641@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Naritaka Oshita (Kyoto University)\nIt has been prop
osed that quantum-gravitational effects may change the near-horizon struct
ure of black holes\, e.g. firewalls or ultra-compact objects mimicking bla
ck holes. Also\, a Lorentz-violating theory as a candidate of quantum grav
ity\, e.g. the Horava-Lifshitz theory\, changes the causal structure of bl
ack holes due to the superluminal propagation of excited modes. The late-t
ime part of the gravitational wave ringdown from a black hole is significa
ntly affected by those effects\, and the emission of gravitational wave ec
hoes may be induced. The black hole quasi-normal (QN) modes are affected b
y the change of the horizon structure\, which results in the drastic modif
ication of the late-time signal of the gravitational wave. In this talk\,
I will discuss how the gravitational wave echo can be modeled and how the
echo model is reasonable from an entropic point of view by counting QN mod
es to estimate the black hole entropy.\n\nhttps://events.perimeterinstitut
e.ca/event/39/contributions/641/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/641/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The S8 tension in cosmology
DTSTART;VALUE=DATE-TIME:20230511T154500Z
DTEND;VALUE=DATE-TIME:20230511T163000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-644@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Mike Hudson (University of Waterloo )\nIn addition
to the now-well known “Hubble tension”\, in recent years a second tens
ion has emerged: the $S_8$ tension. This is a measure of the homogeneity o
f the Universe. Specifically\, $S_8$ is defined as $(\\Omega_{\\mathrm mat
ter}/0.3)^{0.5} \\sigma_8$ where $\\sigma_8$ is the standard deviation of
the density fluctuation in an 8 $h^{-1}$ Mpc radius sphere. As with the Hu
bble tension\, there is disagreement\, at greater than 4 $\\sigma$ signifi
cance between what is predicted by extrapolating the fluctuations in the C
osmic Microwave Background forward to the present day\, and what is measur
ed by multiple probes of the inhomogeneity in the nearby Universe. I will
discuss the diverse lines of evidence for the tension\, showing it is not
restricted to one probe\, but is seen in weak gravitational lensing\, pecu
liar velocities and redshift-space distortions and cluster abundances. I w
ill conclude by discussing prospects for future measurements.\n\nhttps://e
vents.perimeterinstitute.ca/event/39/contributions/644/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/644/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Primordial fluctuations from quantum gravity
DTSTART;VALUE=DATE-TIME:20230512T134500Z
DTEND;VALUE=DATE-TIME:20230512T143000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-649@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Francesca Vidotto (Western University)\nIn modern co
smology there is an agreement that the seeds of structure formations resid
es in the quantum fluctuation of the geometry in the early universe\, but
there is no agreement about how these could be derived from a quantum theo
ry of gravity. In this talk I present a proposal based on the covariant fo
rmulation of Loop Quantum Gravity. I describe how to define a wavefunction
of the universe in this context\, and a how we can study fluctuations and
correlations between spacial regions. The results obtained so far has bee
n made possible by recent progress in numerical computations. I discuss th
e current state of this research program and the possible implications for
modeling the early universe.\n\nhttps://events.perimeterinstitute.ca/even
t/39/contributions/649/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/649/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Wrap Up and Discussion: An inclusive roadmap for cracking Quantum
Gravity
DTSTART;VALUE=DATE-TIME:20230512T180000Z
DTEND;VALUE=DATE-TIME:20230512T193000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-652@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Steve Weinstein (University of Waterloo)\nhttps://ev
ents.perimeterinstitute.ca/event/39/contributions/652/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/652/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Panel Discussion IV: UV/IR coupling in Quantum Gravity: Feature or
Bug?[
DTSTART;VALUE=DATE-TIME:20230511T200000Z
DTEND;VALUE=DATE-TIME:20230511T210000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-647@events.perimeterinstitute.ca
DESCRIPTION:https://events.perimeterinstitute.ca/event/39/contributions/64
7/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/647/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Everpresent Λ Cosmology
DTSTART;VALUE=DATE-TIME:20230511T184500Z
DTEND;VALUE=DATE-TIME:20230511T193000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-646@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Yasaman Yazdi (Imperial College London)\nI will disc
uss a number of theoretical\, observational\, and conceptual aspects of th
e Everpresent Λ cosmological model arising from fundamental principles in
causal set theory and unimodular gravity. In this framework the value of
the cosmological constant (Λ) fluctuates\, in magnitude and in sign\, ove
r cosmic history. At each epoch\, Λ stays statistically close to the inve
rse square root of the spacetime volume. Since the latter is of the order
of H^2 today\, this provides a way out of the cosmological constant puzzle
without fine tuning. I will review the theoretical background of this ide
a. I will also describe a phenomenological implementation of this model\,
and discuss recent results on the statistics of its simulations and observ
ational tests of it.\n\nhttps://events.perimeterinstitute.ca/event/39/cont
ributions/646/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/646/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The H0 tension and sample variance
DTSTART;VALUE=DATE-TIME:20230511T150000Z
DTEND;VALUE=DATE-TIME:20230511T154500Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-643@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Will Percival (University of Waterloo & Perimeter In
stitute)\nLocal measurements of the expansion rate of the local universe d
iffer from predictions of simple models fitted to large-scale cosmological
measurements\, at a statistically significant level. Sample variance (oft
en called cosmic variance) is a key component of errors placed on measurem
ents made from a small data set. For the Hubble constant\, which parametri
ses the expansion rate\, the size of the patch of the Universe covered by
recent supernovae observations has a radius of 300Mpc. The smaller the pat
ch\, the larger the patch-to-patch fluctuations and the larger the error o
n the measured value of H0 from sample variance. Using the H0 measurement
from supernovae as an example\, I will consider a number of different ways
to estimate sample variance using techniques developed for multiple uses\
, and show that they all approximately agree. The sample variance error on
H0 measurements from the recent Pantheon supernovae sample is +/-1 kms^-1
Mpc^-1\, insufficient to explain the Hubble tension in a standard Lambda-C
DM universe. This will demonstrate methods for comparing variations in exp
ansion rate in the universe and what we mean by saying the universe is exp
anding (on average)\, or that galaxies move apart with particular velociti
es.\n\nhttps://events.perimeterinstitute.ca/event/39/contributions/643/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/643/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Panel Discussion III: Holography: fact or fiction?
DTSTART;VALUE=DATE-TIME:20230510T201500Z
DTEND;VALUE=DATE-TIME:20230510T210000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-640@events.perimeterinstitute.ca
DESCRIPTION:https://events.perimeterinstitute.ca/event/39/contributions/64
0/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/640/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Causality at the End-of-World
DTSTART;VALUE=DATE-TIME:20230510T134500Z
DTEND;VALUE=DATE-TIME:20230510T143000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-635@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Beni Yoshida (Perimeter Institute)\nThe success of t
he AdS/CFT correspondence motivates a holographic approach for spacetime b
eyond AdS\, including our own universe. One possible method involves using
an asymptotically-AdS holography and introducing a finite radial cutoff b
y inserting an End-of-World (EoW) brane. However\, previous studies have s
hown that this leads to nonlocal effects on the boundary and violates enta
nglement sub-additivity. In this work\, we address these issues by examini
ng a two-particle scattering process through the lens of holographic quant
um tasks. Our findings suggest that connectedness of entanglement wedge do
es indeed require nonlocal domain of dependence\, but that violation of su
b-additivity can be avoided. We also discuss an important question that ar
ises from our results\, namely whether the non-locality on the EoW brane i
s real or apparent. We argue that it is the latter. This talk is based on
ongoing work with Takato Mori.\n\nhttps://events.perimeterinstitute.ca/eve
nt/39/contributions/635/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/635/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Universality of black hole thermodynamics
DTSTART;VALUE=DATE-TIME:20230510T130000Z
DTEND;VALUE=DATE-TIME:20230510T134500Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-634@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Samir Mathur (Ohio State University)\nhttps://events
.perimeterinstitute.ca/event/39/contributions/634/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/634/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Panel Discussion II: Do we need Quantum Gravity to crack the Big B
ang? What about inflation? fact or fiction?
DTSTART;VALUE=DATE-TIME:20230509T200000Z
DTEND;VALUE=DATE-TIME:20230509T210000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-633@events.perimeterinstitute.ca
DESCRIPTION:https://events.perimeterinstitute.ca/event/39/contributions/63
3/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/633/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Conversations & controversies in the early universe
DTSTART;VALUE=DATE-TIME:20230509T184500Z
DTEND;VALUE=DATE-TIME:20230509T193000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-632@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Phil Halper (Independent)\nFor the last ten years I
have been documenting various scenarios for the early universe in a YouTu
be series called ‘Before the Big Bang”. Having interviewed many of the
leader figures of the field including Stephen Hawking\, Roger Penrose\, A
lan Guth (and hosted debates between them)\, this will be a broad survey o
f inflation\, it’s suggested prequels and alternatives. I shall highligh
t the strengths and weaknesses of the various proposals and give an inside
track of the claims and counter claims in attempts to move beyond the sta
ndard Big Bang model.\n\nhttps://events.perimeterinstitute.ca/event/39/con
tributions/632/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/632/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The role of singularities in the search for quantum gravity
DTSTART;VALUE=DATE-TIME:20230509T180000Z
DTEND;VALUE=DATE-TIME:20230509T184500Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-631@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Karen Crowther (University of Oslo)\nSingularities i
n general relativity and quantum field theory are often taken not only to
motivate the search for a more-fundamental theory (quantum gravity)\, but
also to characterise this new theory and shape expectations of what it is
to achieve. In this talk\, I will explore how different types of singulari
ties play a role in the search for quantum gravity\, and how different `at
titudes' towards singularities can lead to different scenarios for the new
theory. [Based on joint work with Sebastian DeHaro].\n\nhttps://events.pe
rimeterinstitute.ca/event/39/contributions/631/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/631/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Final but Incomplete?
DTSTART;VALUE=DATE-TIME:20230509T154500Z
DTEND;VALUE=DATE-TIME:20230509T163000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-630@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Richard Dawid (Stockholm University)\nString theory
has not come close to a complete formulation after half a century of inten
se research. On the other hand\, a number of features of the theory sugges
t that the theory in its complete form may be a final theory. The combinat
ion of conceptual incompleteness and allusions to finality seems difficult
to grasp. Two main points are made in this talk. First\, it is pointed ou
t that finality claims in the context of string theory are motivated in a
fundamentally different way than traditional claims of finality one finds
in earlier physics. Second\, it is argued that finality and chronic concep
tual incompleteness may be related to each other in a string theory contex
t in an interesting way. The talk ends with discussing possible implicatio
ns of this situation for the long-term prospects of theory building in fun
damental physics.\n\nhttps://events.perimeterinstitute.ca/event/39/contrib
utions/630/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/630/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Experimental Cosmology
DTSTART;VALUE=DATE-TIME:20230509T150000Z
DTEND;VALUE=DATE-TIME:20230509T154500Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-629@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Matthew Johnson (Perimeter Institute & York Universi
ty)\nhttps://events.perimeterinstitute.ca/event/39/contributions/629/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/629/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Panel Discussion I: Where and when will Quantum Gravity crack? Wha
t are we missing?
DTSTART;VALUE=DATE-TIME:20230508T200000Z
DTEND;VALUE=DATE-TIME:20230508T210000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-626@events.perimeterinstitute.ca
DESCRIPTION:https://events.perimeterinstitute.ca/event/39/contributions/62
6/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/626/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Are we considering enough? Inclusivity in Quantum Gravity and Cosm
ology
DTSTART;VALUE=DATE-TIME:20230508T184500Z
DTEND;VALUE=DATE-TIME:20230508T193000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-625@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Jarita Holbrook (University of Edinburgh)\nhttps://e
vents.perimeterinstitute.ca/event/39/contributions/625/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/625/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Spacetime of Acceleration
DTSTART;VALUE=DATE-TIME:20230508T153000Z
DTEND;VALUE=DATE-TIME:20230508T161500Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-623@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Ruth Gregory (King's College\, London)\nI will revie
w recent work on accelerating spacetimes in 3D\, explaining how accelerati
on manifests for point particles and BTZ black holes\, as well as a novel
BTZ-like solution in a disconnect region of parameter space. I will also d
iscuss some holographic aspects of the solutions.\n\nhttps://events.perime
terinstitute.ca/event/39/contributions/623/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/623/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Welcome and Opening Remarks
DTSTART;VALUE=DATE-TIME:20230508T131500Z
DTEND;VALUE=DATE-TIME:20230508T133000Z
DTSTAMP;VALUE=DATE-TIME:20230610T112731Z
UID:indico-contribution-39-620@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Niayesh Afshordi (University of Waterloo & Perimeter
Institute)\nhttps://events.perimeterinstitute.ca/event/39/contributions/6
20/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/39/contributions/620/
END:VEVENT
END:VCALENDAR