Speaker the first fruits
I stood by my mentor.
Offered.
Up My Life in dance days
ninety two ninety three
this was now one of centers
in the country of the world.
Because it is as if you three before your
running history was a series of for
almost eight years to run through.
For regular.
Distinguished career look at
this built on our skin or.
Like the spines of years ago those were
the something the president
of the National Suicide.
Mission.
Search expands many areas
negotiation will districts
where you live near one of them but
he has also gone.
Very one usual war all of us
spoke of arises from the medical
point of view that in fact the widow who
publishes the work rather period is also.
On your block calls on their feelings
interest and who would know if over
the need for going to hear it
right now there through all
approaches one hundred value what good
is wrong one of the street you know.
If you're.
Buying a house they're going to.
Thank you thank you very much
Bob Look I mean as you know in.
Problem A Not like me to say this but
as you know in academia
there are no bosses so.
OK So Pablos told me that I
should give the stock doing
a broad introduction to quantum gravity
and do quantum gravity the students
were interested in this so I'm going
to make it rather pedagogical and
give you some highlights so that to
what evasions The first is that our like
to give you a general introduction
to quantum gravity as a whole.
And then in the larger part of the talk
I would give you a broad overview of
blue quantum gravity two examples.
Two of the areas to which is.
Applied are most interesting for quantum
gravity are the very early universe where
effects of economic Alex and
gravity come together and the second is
deep conceptual puzzles about black holes
so I hope to cover both of them but
if I don't have enough time then I'll
just cover the cost of all of your part.
So they are straight both of these
things will illustrate deep conceptual
issues of quantum gravity that
are addressed in look and gravity and
how contact with observations is baled
in spite of the large order of magnitude
in scale that separates quantum gravity
from rest of physics however this is
not a exhaustive review by any means that
the samples that I'm going to present.
So conceptual starting first so
I started the resistance
to accept Khana mechanics as
a fundamental theory is well known.
However people like to say thing that I
Stan didn't respect quantum mechanics and
believe in quantum mechanics
it was opposite in my view yet
the deepest respect for
quantum mechanics and but
he just felt that this could
not be the final story.
And he was in fact one of the the first to
raise the problem of unifying generally
pretty with quantum theory and this is
really even one hundred sixteenth so
very soon after his seminal
papers on general T.V.
He said that nevertheless due to in the
atomic movement of electrons atoms would
have to radiate not only electromagnetic
waves but also an energy
if only tiny alarms as this is hardly true
in nature because if it was just classical
then just like in classical relativity an
accelerating charge would actually radiate
the quadruple moment of the that and
would also be changing in time and
would be radiating waves and
then then the latter would be unstable and
therefore it appears that condom theory
would have to modify not only Maxwell in
electrodynamics because in Qana mechanics
we all know that there is a ground state
five billion atom or for all atoms and so
they don't have to keep radiating forever.
So the same thing should be true for
gravitation so
he said the same thing so
that the quantum mechanics
defy the new theory of gravitation which
of course he meant generally to Vittie.
Now this was in one thousand sixteen
we have more than a century later and
physics has advanced tremendously
over the last century but
this problem of unification of the realty
of tea and quantum physics is still open.
While now the standard answer we have and
it's correct is that there
is no experimental data with
direct I mean if occasions on
the quantum nature of gravity.
But on other hand if this is the only
reason then it should really be a theory
is heaven right if this works better that
then every one of us should be able to
create and write down the quantum theory
of gravity and if there is only obstacle
because we just like there are none
you know nobody is constraining us.
But this doesn't happen.
Not a single satisfactory condom theory of
gravity exists today so why is the case
in my view it is appalling this
really deep conceptual issue here and
that is that in general activity
gravity is encoded in the very
Johm it of space and time the most
spectacular predictions of general
relativity the Big Bang the black holes
and now we are low gravity still waves.
They merge from this and Corey and so
this suggests that if in fact we're going
to our conduct theory of gravity then.
There should be accompanying quantum
theory of geometry in other words just as
generative it is rooted in Ramadi and
John metry differential geometry
on them gravity should be rooted
in suitable for them the money.
And then the question is if Germany
becomes got a mechanical how do we do
physics because then we would not have the
space time continuum in the background so
we need new concepts and new mathematical
tools well learn how to where to live
learn how to lift the anchor that Titus to
background spacetime in all other eighty
years of physics including quantum field
theory high energy physics where a bag of
spacetime given to us and then we do
develop frameworks concepts using this
background spacetime now somebody takes
the background spacetime of A from you
everything including spacetime geometry is
kind of mechanical then what how do you
even pulls the basic questions so
we had to really live this anchor and
learn to say in the open seas and
this is something that we learnt
relatively recently and this is
the reason why it has taken so long and
then there are several years in progress
these are some of the approaches I wrote
down noncommittally
geometries twisters and I G.
calculus to create in quantum
gravity which our lives as gravity
calls are sets of symbolic safety
causal that I make a triangulation.
And then A.T.F.
safety conjecture of string theory and
look quantum gravity and so on.
Now most of this is would say that well
why are people completely following this
completely the disjoint ideas very
very different ideas why are they so
much driven by their taste about what is
fundamental and what is not well it is
primarily because there is no experiment
direct experimental checks so
that approaches are really driven by
intellectual prejudices about what
are the current shoes and
what will be taken care of once the issues
are addressed properly now again you
might feel thinking this is a little bit
strange that there is something
objective and fundamental as physics and
for the fundamental problems in physics
the issues of taste are important but
there's a very nice
court from seeing young.
In the Selected Papers commentaries so
he comments on this electorate and he says
that taste and style has so much to do
with physics may sound strange at first.
Because physics is supposed to deal
objectively with physical in us.
But the physical in US A structure and
once perception of this structure one
spark she ality to have some of its
characteristics as being more fundamental
against and I worsen to are those.
Are precisely the elements that make up
one's test so when we are inventing new
theories when we have creating new
paradigms we are really driven like in
other areas by distaste issues of test and
what is fundamental and what is.
Once all on perception about what is
really important in the structures that
are way uncovered and thus it is not
surprising that taste and style are so
important in scientific research and this
is what is happening in quantum gravity.
Now as Pablo said there are many
although there are these many approaches
that do which are sort of on which
lot of work has happened and it is.
Theory and look quantum gravity
that I would like to talk about.
And so
again this is a quote from Scene young.
And then in sync theory
the taste is really a DI D.
A that unification is central.
And there was until recently
some other sion to the idea
that spacetime geometry is fundamental.
And therefore what happened is that one
began with but a bit if on a field theory
in flat spacetime applied to
generally tutti found a general it is
not real normalise a bull in the standard
sense I don't mean cascade space and
the whole idea is that guy would should
just be another one of the flutes there's
nothing fundamentally about the fact that
it is encoded in geometry of spacetime.
And therefore people's out of bed led
to modification of General Relativity
a devotee of theories which turn out
to be ultraviolet reliable as able but
they are not unitary Superguy beauty which
adds supersymmetric matter which has not
been observed so far but there's always
hope that just around the corner but
I should also say that
the hope has been there for
thirty years that is
just around the corner.
There is string theory with various
incarnations began in the party base and
string theory metrics
models the so-called F.T.
an entity of this is of Wafa and
here is M.
stands for mystery apparently so we don't
know what the theory is the people who
tell you that we don't know what that
he reads and then this idea of see if
the correspondence in this correspondence
it has been very powerful and I would
think I think it is fair to say that we're
still working the last ten fifteen years
in string theory more than fifteen years
now instinctively has focused on this so
where is the idea the idea here is
that that gravity in space time which
is called bulk is really described by
gauge theory on the boundary of spacetime
one dimension less and that's why this
called sometimes holographic and so on.
And the great success of string theory
are but idea if the correspondence
as I'll explain a minute is released
applications to other areas of physics.
From the generally to decide on the other
hand going back to what Young was
telling us namely distaste
about which characteristics
central partiality to some characteristics
the postulate is the baggage
our independence the fact that in general
the Timothy in the classical theory
everything is dynamical in any
other branch of physics spacetime
is not dynamic it is given to you is a
stage on which things happen in general if
the state joins a group of practice
everything is that I make a lot of it.
So that is a central issue is what the
viewpoint is from general to decide and
then again there are several approaches
that is can only go conversation was
initiated by Dirac Peter Bergman John
Wheeler and by the way it but integral
approach by Charlie Misner Stephen
Hawking Jim Hartle and other people and
then there is the quantum gravity which
has worked which sort of goes ahead.
In blip these approaches in
terms of Hamiltonian theory so
along these lines which
is used in cosmology and
black holes and spin firms which is
called which really is particularly.
As a bridge to the low energy physics ten
years ago I wrote this but this little
review which answers kind of the questions
about the relation to the theory why would
the two theories why when he's doing
what one is doing in quantum gravity.
So there's a contrast what is in what we
know about string theory look quantum
gravity quickly syncing theory as we just
said I just said unification is central
and super symmetry is an important
story on which everything is bit and
also typically one thinks of
in fact one needs hire to men.
So if you got both balls on from Young's
than spacetime at a fundamental level it's
supposed to be ten dimensional and it is
supposed to come down to four dimensions
by some kind of compact if occasion and
then there is a whole lot of it that I
just mentioned the idea that guy would be
in the bulk is really included in some
gauge theory on the boundary of spacetime
so this is these are the ideas and
there's a very nice review by.
And yet I have long and
got a Horowitz which is called Quantum
Gravity via unification and a long Graffy.
Look while I'm driving on the other hand
the bag on independence that everything
is that nickel including spacetime
geometry Everything is called a mechanical
including spacetime Jummy that
is kind of a set of central and
it is based on a condominium money
geometry and it also has a built in
out all of current cutoff and again in the
same volume which is the centennial for
general activity which was commissioned by
the society international society there's
an article that I wrote in my Detroit and
Colorado belly from generally to quantum
gravity the current meant trust in
these two things are the following as I
mentioned in string theory the thrust
of going to idea of C.F.D. and
now what one does is one uses this duality
is not proved it is a passionate but
has been extremely successful postulate in
the sense that one should just say that
is true for
some reason then one can use methods from
classical generally to begin
super gravity to solve condom
fealty problems in the stronger
playing limit of interesting physical
systems including Now some of the systems
which come up in can this matter T.D.
So what one is doing is what is taking
techniques from gaiety to solve
problems in other areas of physics so
in this spect it has been quite nice
to see that gives us a nice feel for
unification for you.
The fact that there is actually
the same idea underlying all of physics
look on a guy would be on the other hand
has focused not on other interactions but
on fundamental problems of
quantum gravity proceed so
one focuses on longstanding problems of
quantum gravity itself problem of time
space time evolution when John
materialist quantum mechanical
Taming of the Big Bang singularity the big
banks in the light is dissolved and
is replaced by big bounce
physics doesn't stop physics and
well behaved quantum physics as well
behaved all the way across the what we now
call Big Bang the pretty inflationary
dynamics and large scale anomalies and
seem to have been addressed gave
the guy we don't propagate or
an end point functions in the theory or
are constructed in the theory in which
there is no background spacetime so
these things are really
some kind of contrasting that really
diverse in what they're focusing on but
I think both are contributing interesting
ideas and interesting results so
I don't park now in lukewarm gravity
what is the basic framework so
I just want to summarize it very very
quickly to give a general feel for it.
So the idea here is that generally
charity is formulated using
quantum Riemannian geometry.
And there is a specific version
of continuity money Jummy tree
that was developed by a bunch of us
in the one nine hundred ninety S.
So it's almost a decade it is
a mathematically very very solid well
founded theory and it takes the idea that
gravity Ijaw miter very very seriously.
Then in particular there is
no baggage on John metry.
The spacetime Giambi disc on
a mechanical and dynamical
is interacting with everything else from
the beginning from birth spacetime is
born quantum mechanically just as
matter is born quantum mechanically and
technically this is called that if
you Marvie have been a variance and
the interesting thing
is that this principle.
Statement from General Relativity does.
That there is a unique Can
a magical Hilbert space and
the unique operators defined on them
such as geometry cooperators for
example the area of the surface
you take this surface you want
to calculate is area so of course in this
room the geometry is almost Euclidean So
it is just this length multiplied by this
length that is eighty and this area can
change continuously if the job if we were
killed in this room within the black clear
for example then they deal with more
complicated but there is still a formula
and the continuous then legitimate can
change continuously I can I can get.
This brief case appear and reduce its
area by some by arbitrary amount but
in looking at them gaiety the area of a
physical surface like that is an operator
just like Hamilton is an operator I
get a momentum is an operator and
this operator has is a cell for John
operator so we can look at the spectrum or
as I get values and
just deal a discrete eigenvalues So
it's like the energy levels of a hydrogen
atom if you like so either cannot change
continuously in particularly the Syria and
then there is an area gap and
then down are they and furthermore
the spectrum that eigenvalues of this area
operated exponentially these
are mathematical calculations this is not
a postulate it is really derived and
because a cloud explanation for
large areas continuum approximation is
very very good the same thing is true for
the lives of lesions on the order or
a lens of goods.
So it's a discount ties in
a fundamental but rather subtle me.
Not really just like how demonic
oscillator one planck length
squared to plant length square
to Planck length squared and so
on but they actually come out
exponentially for large areas and
as I just mentioned there's a fundamental
smallest area which is the area.
That is a fundamental
microscopic parameter
which then Good heavens the macroscopic
the law school but I built this and
which in which at which quantum
guy would effect become important.
Now this area gap.
Is qualitatively but
only qualitatively similar
to the energy gap in the superconductor
you see as you all know electrons are from
yawns the fall is that we just had some
electrons by themselves then so but
then that would not be possible because is
a collective phenomenon is a concession
that is that required but
what happens is that the electrons conform
to pop bands because of something or nonce
having to do it like destruction and so
on so they form the scope of bass and this
group of players behave like Clinton's.
Like their songs and these will once
again then tendency but of course if your
temperature is higher than the binding
energy of a group then superconductivity
disappears so the energy gap is a
microscopic but I made up superconductive
ity and that critical temperature is
the macroscopic but I meant it and
then the B.C.S. theory tells us that
the critical temperatures proportional
is constant here which depends on
the material times the area get.
So similarly in general it's a pretty
out if you look at them gravity A.D.I.
gap is a fundamental part of meter like
the area like the energy gap up here and
the curvature of the maximum value of the
curvature of the backs of Mumbai you this
of energy density at anybody in
the universe is not infinite anymore but
rather it is a constant
divided by a gap cube.
If you will to classical physics
then they get just disappears or
become zero and therefore these become
infinite so this is like what happens for
the ground state of the hydrogen atom
if you look at the guns that energy there
is a spot in the denominator if you let
go to zero grounds that energy
becomes minus infinity.
As you nightly imagine because
a potential is singular of the origin
is minus infinity same thing
here classical general T.V.
the maximum coverage is infinite but
in lukewarm gravity it is finite
because of the kind of geometry
effects the fundamental accelerations
of geometry are polymer like so the
fundamental studies are not like the V.
like you know like on delicious like but
the bit you quantum gravity will think
will have us believe but
rather than like the one dimensional.
And this three dimensional
continuum that we see across.
Is an approximation that rises when
this one dimensional treads one
dimensional excitations condensed in
certain sorts of precise fashion and
then I argue that I like his that of my
Should you see my shirt is fundamentally
a one dimensional object because if I
take a magnifying glass I see that is one
by one dimensional threats but
the threats are close enough that for
all practical purposes it really behaves
like two dimensional object similarly
space behaves like a three dimensional
object although it is when it does
the basic question you are atoms which are
really fundamentally one dimensional which
are then condensed into into this three
dimensional cont'd pattern continuum.
Then the fundamental states are called
spin that works with our kind
of medium bases of states that diagonalize
the geometry cooperators So for
example a spin that work is like that
yes some links a graph if you like and
some notes the WM is concentrated
here along the north and
the area any any surface which intersects
this note this this this this link and
does it with certain area so
links deposit of area on any surface
that intersects the north is a quantum
chunk of space and therefore it has but
not as it was some symbolic and
this is not just fiction I think these
are very detailed mathematical results
that one or ten years the operators.
Specter are being worked out and this is
just as somebody what I would dynamics so
conduct in America is well understood
quantum Nanami's is not Dylan the story
this is still an open issue certain
status in the following The Hamiltonian
methods have been used for conduct and
I mix as we'll see in the next part that
well suited to treat problems of of
the very early US and the A.P.I.
gap sets an upper bound on the energy and
a legit entity and therefore
the singularity of Big Bang singularities
actually came as within a minute.
The padded Diggle framework is
better suited to make contact with
lunatic on a field theory this patent
deals are called Spin forms so
spin that the work has links and modes and
if you think of this as being a time
dimension then the time a whooshing of
a spin that work gives rise to a spin for
so you got this this link
it was at the surface but
then knew what this is
can also be created and
then interesting dynamics happens but
this new word Texas created.
There is a promising spin for battle that
has emerged to give us the dynamics and
using it things like Point functions or
guy we can propagate as I've been
calculated and ever bar the one has
a finiteness built in and
if in fact the cost burden constant is or
should be positive which appears to be the
case in a way you do worse than that also
in the infrared in infinities and as I
said application is due to this end point
function you give me a two points appear
in a real spacetime region between them
I want to know what the propagate is
inbetween so I put the spin forms
in going from this surface to this surface
in between does not continue Jummy tree
only discrete geometry is some of
the geometry and then in some appropriate
limit if in fact this is the end state
appear corresponds to me because space
then you can actually drive the guy down
propagate or to THE LEAD YOU are the.
Important issues still.
Remain and but partial results
to date have been promising and
Currently these ideas in spin forms
are being pushed to the very rigorously
there are but
two hundred fifty people working or
looking at the gravity leave two years
that is international meeting and
that these things are discussed OK now
I would like to come to applications.
As I mentioned in the very
beginning of the talk
the important applications are to
the very early universe and
black holes that is very condom guy with
the shoes are faced sort of said squarely.
So let me just to begin here with
a summary of where we are in our
understanding today of the current
paradigms of about the early universe and
there are a lot of Apple issues and
how quantum gravity theories might
address those open issues so
the early universe was extremely humble
genius so when the universe was about
at that the cosmic microwave background
the area era so it's about three hundred
eighty thousand years all our young three
hundred eighty thousand thousand years
younger than the statement is that the US
was extremely homogeneous except for
tiny in which it is which are one
part in ten to the five fluctuations.
And one of the primes of modern of
contemporary physics that we should all be
extremely proud of is really that starting
with this one point part in ten that and
the five fluctuations starting with the
initial data you can now use known physics
you know astrophysics gas to physics
generally put the patient theory to
prove and to understand to calculate what
the you will should look like today and
the numerical simulations agree with
what we observe extremely well.
So to me this is very very interesting
because you know if I just go back to this
these numbers appear these are three and
eighty thousand years this is about
fourteen billion years if you take
the racial the picture of the.
Suppose you had a human baby and Suppose
you took a snapshot of the human baby
when the babies one day or
this is a snapshot.
And suppose you know a theory
here you understand.
You understand everything by by
chemistry everything about the human
body completely Well you've got a great
theory that you put in the computer and
ask what this is going to look like
when the being is hundred years old and
the computer churns and reports
the picture and supposing we are so
good that that picture is accurate this
is there we are with the physical in
US This is the one bit early baby and
this is the hundred year old or
person that are good that has grown and
we have today understanding of how and
when came from bad to here so we should we
really live in the extraordinary era and
we should all be the problem that.
OK so the plant the question
is the early the following
The question is OK this is ambitious
This is a great achievement but
we would like to understand how
it is that in fact this structure
was formed in other words why did this one
part in the tend to fight you know would
you need an appeal in the first place and
all this is when you also see an eighty
thousand year or was that before
that created these fluctuations and
the leading paradigm again
it's a fast Skokie I'm so
I'm not going to own the copyrights but
the leading is that of inflation and
the success of inflation is that it
correctly predicted almost a scaling that
in the power spectrum of the microwave
background and it is scaling that in but
there is a slight tilt and
back tilt that is predicted by inflation
was confirmed by the plant mission to
ten sigma level so extremely well.
And really inflation
starts with calculation
led spacetime geometry still can be
taken classical believe it or not.
Because at scale the energy
scale of the curvy The scale
is about ten to the minus twelve or
ten minus eleven times the Planck scale so
it is it is pretty classical at
that time spacetime geometry but
the statement is that it's still
huge compared to the everyday life.
Everyday life so imagine a cinema's
black hole using allow the curvature on
the surface the solar mass black hole
near the horizon incredibly large
Well the curvature in the universe at
the early times when inflation begins is
ten to the sixty five times that of the
horizon on the SOL about the black hole
people don't I don't buy this amount
people they were calculated on that but
this really extraordinary and yet
classical general attitude is fine
because you can because it is
the plan scale is still full orders
of magnitude higher it is ten to the.
Seven seventy seven to six times
larger than the whole of the coverage
on the horizontal Solar about solar mass
black hole OK so it's really extraordinary
and furthermore it leads to an unforeseen
strength striking accounting for
the cost for Genesis namely the very early
you knew was that we had well it was
really the video us at onset of
inflation was as one machine years
as quantum mechanics allow it to
be is a quantum mechanics I mean
you all know this in the vacuum the energy
that the fluctuations the electric and
magnetic fields are not zero in the vacuum
for the quantum electrodynamics
that quantum fluctuations because of
Heisenberg Uncertainty Principle.
And the statement up here is that
Similarly if you look at the cost of
logical put the basis they could be in a
vacuum state but there still fluctuations
and except for this quantum fluctuations
the US is completely homogeneous and
I start dropping at the onset of inflation
and then these vacuum fluctuations
grew to the cost me you know what
unit does not cost me micro.
Background and
then they grew to the last construction so
we're leaving our place back by averaging
of the possible Genesis took time but
the universe was very very young.
All large scale structure that's good
vacuum fluctuations it I think is
thrilling idea if you believe you know
if you're a speck on the mechanics or
kind of hinted but
the paradigm also has some limitations it
is incomplete the paradigm continues to
you generally shifty with its Big Bang
singularity it just begins in the middle
when the space time curvature is about ten
to the minus eleven times the plan cover.
The particle physics issues they
does the in for Don come from
what I read sport then there is a
potential comes from how the particles and
fields of standard model created during
the heating from this little town and
then that icon the guy with
the shoes Well there is there is
in inflationary models there is still
a Big Bang singularity you would expect
that in the real final good physical
theory there are no infinities
therefore the singularity it really
did not was wasn't there and
therefore the question is can we really
get the resolution of the singularity from
from appropriate first principles can win
consistently extended Fishley scenario or
the eleven or twelve orders
of magnitude in curvature and
density all the way to the plank
regime these quantum gravity issues
are addressed in look Congress policy so
it does not address this particle physics
is use it only addresses these issues
about what replaces the Big Bang.
And can we extend the inflationary
scenario all the way to the plank Rigi.
So now there is a really great
interplay between theory and
observations first what we had in
lieu Quantum Gravity is that there is
a ultraviolet completion of the standard
inflation it looks one of the smaller did
the Big Bang singularity is naturally
dissolved and is replaced by big mounds.
So you just use look at the guy with the
ideas apply them to cosmological models
you evolve using the condom equations
you get you find excellent agreement
with classical general itty bitty all
the way up to the inflationary regime and
even before inflationary regime until
the curvature is about ten to the minus
forty to the minus five times plan Planck
scale after that there is a drastic
departure and the Big Bang doesn't
occur but is replaced by a big bounce.
So so the basically got the classical
theory where got the scale factor and
some matter fees for example a scalar
field that is now replaced bike
with a function for the scale factor
the scalar field so the idea here is that
you don't have a specific than I am
because Project three but trouble ya got
probably the amplitude of maybe is than a
project Aries you know there are specific
Friedman Johnny tree but you are probably
is probably the distribution
of various Friedman amplitudes which
I sharply peaked about some but
I love that there are churches which
are which are group taken into account.
The condom state a part the basis now so
when I got new spacetime where I got
a condom they function of Java tree and
the put the basins of the two tensor most
of the scalable evolve along our
discounting spacetime geometry so
what we have to do we don't let
an extension of Condor Philthy
in classical space times
to the field theory on.
Cosmological quantum geometries not not.
Condoms spacetime not classical spacetime
and this was done in about in two thousand
and nine and that's when applying applied
systematically between two thousand and
eleven and to the thirteen fourteen and
what we find is that when we do
that very well the part the basis.
There is agreement or
standard inflation for the for
the they were lanes which are not
the longest Babeland that one can observe
in this while of decomposition for L.
bigger than equal to dirty smelly or else
and right while in decomposition means
the larger Vaillant larger else
means smell of evidence so
your statement is that for as bigger
than equal to thirty for almost all but
the longest wavelengths in fact there
is agreement to the study inflation but
the pretty facially dynamics of lukewarm
cosmology can leave imprints on the larger
than most there's an unfair scene I'll
tell it in for late in the play because
really going to guide effects we stay
in the singularity have to do the outer
wallet but their effect of the condom
Java tree as opposed to classical
geometry the effect of the quantum
Jummy trick is really all the need for
a behavior of the this is not something
that we're not known before this is
what something found and now we understand
it quite well this opens the possibility
that anomalies that the plan data may or
may have been data shows.
In quantum gravity so plan data has
some anomalies that not what we sort of.
Departures from standard freshly
prediction at the longest wavelength and
therefore therefore this opens a
possibility that this will happen thus you
have points of window that is
complementary to those based on particle
physics and now I will mention I will
explain this point in some detail and
for students the non-technical details
non-technical accounts of this of these
recent developments in the security
plus there are three three articles and
secure plus that describe what is
happening appear OK So the first
thing last thing you did in a solution so
here what I've done is the start of been
skipped attentional and inflation is
a seven protection which is highly.
Cesspool so we'll just look at that in
classical general maturity the following
thing happens this is
the influence on the field and
this is the volume of the universe.
Are if you like volume of some region
of the US You think some region and
wanted to how it's all in changes and
what happens is that during inflation
changes you know exponentially.
So in effect only somebody here and
rolls down the potential and
it rolls on the potential you knew
what expands out exponentially but
you can look at the evolution
backward in time.
Usually one starts year one doesn't
look at backward in time if you look at
backward in time then they inflict on
the turn around and in classical general
Nativity it goes up because minus
infinity and the water goes to zero and
this is the Big Bang singularity so
appear classical general entity and
they just continues there is a look
at of gravity lukewarm cosmology we
find that there is actually bombs the U.S.
bounces it reaches so to say.
A maximum curvature maximum energy
density here and then it bombs.
And therefore the Big Bang
is replaced by a big bomb
Big Bang is replaced by a big bulbs
the singularity is actually dissolved.
What is behind the singularity resolution
I mean surprising So how does this happen
Well the key modification is really condom
Jummy tree as we just saw so I started
sequences are changed what Einstein's
equation they say that the I stand.
Out of judgment three is equal to the
stresses energy tensor constructed out of
matter here the left hand side actually
changes but in a colloquium it is easier.
And can have the changes move
them to the right insight and X.
and see what happens then the comparison
with I States a question becomes
becomes easier when we do that.
The classical general Richard Friedman
equation is the scale factor doc or
a that is Hubble paramita
squared is equal to eight by G..
Or three.
And then what happens is the following
that since discarded the appear
it's the energy density is positive and
this standard matter energy density
is positive therefore of course it's
called quantity is always positive and
it never vanishes any of it and therefore
the statement is at any finite time this
doesn't vanish Therefore if you were
a doctor or aide there were vanishes So
if a dot is positive it remains positive
the US is expanding it just remains
expanding if they do which is
contracting it will demand contracting.
Well what happens appear is appalling
that in general to look at them gravity
this equation produces a correction
it is a road you want to borrow soup
to pieces about of energy density which
goes as what up on the eighty a gap that
I told about which is about
forty one plank density so
when this happens the light inside
does values and therefore you can all
contact you knew us with a don't negative
then a dot of energies and then or
can become positive and therefore if
you go backward in time is repeating
the singularity you just reach a reason
that a dot of average is a still finite
the new is finite the density is fine of
the car which is finite and then the U.S.
bounces and that happens when the density
is equal to the Big Bang is replaced
by quantum bobs and there is a nice
separation of scales appear these effects
become negligible when the energy density
becomes small compared to the room and
in inflation this these objects are but
at the minus eleven zero
I do them on a stroll so
this equation this term is negligible.
The mechanism is not that there is
a physical matter negative energy for
example or new Barbican missions like
it how to Hawking description but
condom geometry creates a brand new
repulsive force in the plant regime
were developing the contrast
of traction and
this is something that is
really understood but what.
I have to do not approach to do.
And also in the consistent histories
approach that people like to use in
the cosmology that many generalizations
just simple freedom of model
special coverage is included
cosmology a concert is included and
national groupies are included and the
quality to some of these the following.
Anytime the matter density
of the curvature and
to the plank of the repulsive
force dominates and takes or.
Classical general if you do
even this magic density or
curvature because Planck scale
it will continue to grow.
The repulsive force dilutes it and
prevents a blow up OK now.
What next question that you might ask is
Why does this matter why does prima facia
dynamics matter at all
OK The Big Bounce is really the big
bang is really dissolved with the big
bombs but you know little you consequences
because you often hear for an inflation
of people you see inflation people say
whatever happened to be fed inflation is
irrelevant because that is all left to me
during inflation what is the idea behind
the idea that what is idea behind
the claim that everything is
washed away well idea is a folly.
This is a cartoon this is time
this is these are led scales and
this is the radius of curvature of the
universe so during inflation that it is of
coverage almost constant but near the Big
Bang the curvature blows up the radius of
coverage is one upon which a square foot
actually goes to the radius of curvature
goes to zero and the idea that people
usually have the following that well.
If you actually had a million words which
are observed today which are already
inside the curvature radius then if you go
all the way Big back to the big bag they
would always remain inside the curvature
radius which means that of Evelyn would
remain less than the curvature radius this
is fine now why is this important but
if you look at the equation that go to
this Milt's you find something that you
physically expect namely the curvature of
fact they would Lucian only but they lent
is larger than the curvature radius if the
coverage is ready as you would and they
WILL IT IS THIS much the mirror doesn't
even experience the curvature at all it
travels a loop is in McCaskey spacetime so
really the statement is that if
the use of a villain is less than that of
the curvature radius these mostly travel
as in a casket spacetime nothing else
will happen so if the most very inside
the curvature radius of the onset of
inflation you don't expect anything much.
To happen in the past but now these
changes a look at them again time and
land now we look at a cosmology the lead
skin the curvature does not blow
up at the singularity the coverage of the
bows is finite which means that the length
scales the curvature radius and
skin doesn't go to zero but
is actually finite up here and now you
can have some more which actually have
of they were larger than the curvature
radius they evolve in time during this
time in the Planck regime they actually
experience curvature they get excited and
therefore when they come at the onset of
inflation that no board in a vacuum state
as they would hear but that an excited
state and therefore the initial state
that is used in the inflation the body to
be vacuum is not realized for the longest
we have the more the shorter wavelength
but it is still the budgeteers vacuum so
the power spectrum of the prediction
will listen but for the longest revelent
the situation is very different so this is
the interplay between the ultra light and
the infrared is as well it
effects of quantum gravity
that result the Big Bang singularity that
makes the curvature of the bounce finite
rather than infinity but once it is done
then we can out there support the basins
which actually was very real and
is larger than the curvature radius and
therefore the experience that the the
curvature the dynamics of the geometry and
therefore they get actually excited and
that different then lastly one might say
OK that's all fine these more excited but
so what during inflation they were all
just get diluted and a few exceptions but
even during inflation they
just get diluted this
is the argument that inflation people used
to get about five six ten years ago but
even I give and new not Parker and
others are sure that in fact
there is an effect like a stimulated
emissions just like in a laser if you
are a few builds which are excited
these boards are excited then do.
Expanse of the universe may well
excited most I created such that
the density of Mertz which are excitedly
made the same is not that I got a fixed
number of excited moves fixed number
of executions and then they whoosh
an exploration expansion they get diluted
away day the fact that their own city of
this exhibitions remains the same and
therefore we have year at the end
of inflation this Morse can actually have
some effect So what effects do they had.
And are the important forms of Asians So
here is the paper that the Planck mission
published and they talked about
this power deficit at large angular
scales so basically inflation predicts
a power spectrum and what the blue map as
well as Planck are found is that there is
a power deficit at the largest angular set
the power is actually suppressed compared
to what the theoretical prediction was and
then they go on to say there's also
a dipole or power power symmetry and so
on and then they go on to say that the the
case for anomalous features of the same B.
has been strengthened and such and
our bodies are attracted considerable
attention the community says they could
be visible traces of fundamental physical
processes or caring in the early universe
so we don't know it could be statistical
fluctuation it could be various other
things but here is our chance for
Quantum Gravity people who are working so
long here is one effect that
experimental observers are telling
us what our origin Planck scale and
therefore we should examine what is
happening and that is what the so
this paper is from two thousand and
fifteen but just before that I had some
meetings with Plant people they told me
that we should really look at these things
and that's what we'll be doing since
about two thousand and thirteen and
so what are the effects the effects
in lives you see of the following so
we here is the power spectrum and
here are the they have.
Numbers of the various Morse case studies
of people aboard that that plant mission.
That is often used in cosmology.
Observational missions.
So the what happens the following
that here is a bunch Davies
on the standard fission power spectrum and
here is a part spectrum
that is present predicted by Newport of
the smallest so you can see that for.
Larger Kieffer larger big numbers.
That means for smaller angular scales or
for larger values of L.
while M.
decomposition there is complete agreement
with inflation just as we expected
from the from this picture appear
because it is only longest wavelength
that will be affected by the sky which
are the small of Evelyn Morse they don't
they that are going to be doing the same
thing as they do in standard inflation so
it's really the longest million words that
are affected and
there is actually participation.
Then the next question is really what
can we have that primary a spectrum
into the into the sea else that are always
shown and we again see here that for
until about an equal to thirty that is a
great agreement with the Elbe survey sions
the body Davies of the standard
freshened that vacuum and the as you see
prediction appear but far less than
thirty that are that his departure there
is a power suppression file Q.C.
and got continuity analysis be done and
we find explicitly that bell Q.C.
prediction provides a better
fit observations than the standard
inflation for the norm for this but
this Lobos appears I should also say that
the error bars here are quite large but
nonetheless these are the I mean.
The missions had already said that
in spite of the error bars this
participation here and
that is what is really reproduce.
Now this is what I showed up here is what
is called the temperature temperature
correlations and this is what has been
publicized very much but there are also.
Sophisticated correlations they have to do
with temperature and electric polarization
correlations and this is something the
plan that I've also been has given us but
up to only fifty and
the question is what happens in the.
Less than fifty R.P.M. and again what
we find is that they use a prediction
that the power suppression relate
to to study deflation appear and
same thing is happening with
the electric electric polarization
again this correlation there is a power
suppression so the point up here is that
elk you see this mechanics of we talked
about the lead leads to power suppression
at the largest angular scale there's
a whole other analysis is that even I.Q.
is done about they
missed this critical and
I was on topic which is much more
non-trivial in that he shows a better fit
with a Miss period and
that's a property without affecting the.
Limits on the go Shannon In other words
you see respects the limits on gauche.
Gauche energy and yet produces a mystical
sort of way that we're seeing OK So
I think you have time I'll just go to
this is the last part last part and
I'll just summarize up here last part
are supposed to be a black holes and
the whole issue about they
formation lost power paradox and
even information loss issue and the main
message that I wanted to tell you was that
the singularity is the vision we saw in
cosmology also occurs in black holes and
because of that singularity resolution
in fact the whole way of and
then lies in the information loss.
Issue is something it's changed and in
particular there are no fire walls there's
no necessity for war fire walls that I've
been at all get OK Let me summarize.
Where you're somebody and so
you can just really matter.
In.
The.
Moment.
So that as OK so the two questions appear.
The the statement is that I'll call you.
A dark energy which is in order for
the infrared so that there are good frayed
infinities if they're not dark energy then
that I'm Fredericka infinities up here
then there are some detail
which sure why the dark energy.
In the very early US is very small but
in the this it would loosen it is going to
be large but there's no sort of these are.
These are arguments based on.
Some some group of groups in the parameter
space that not sharp enough to give you
any quantity of prediction about how small
you should be these are just quality to
ideas appear about dark matter it doesn't
have any predictions at all because it is
not something that is directly related to
it's not a purely Gravesen origin unless
the dark matter happens to be something
like intermediate black holes on thing but
at the moment does not have
anything to say about dark matter.
Of.
Those who are.
Still in.
The fight for very good part so.
The question was whether
the big expansion.
Might sell suffices to give
your Green made with with
observations without having inflation the
order in face in front on inflation but
then shell or something like that so
the statement is so far.
The.
The.
Say has really no substitute for inflation
other words the calculations are done.
That there is a TON of
the potential however
the best successful scenario
is really the start of.
A bad really came from pure gaiety without
putting any matter in it it was really
out of place are square gaiety in other
words like Rajan or not just odd but.
Now if you just opposite of scary guy
would be then I would then that the.
New Kind of gravity is perfectly you know
it gives you all these results that we
solve because these it is us are the same
Mr Binns conflation so they give you this
is that for the both of these in some
ways to see why the leading corrections
that will come from new quantum gravity
which will include our squared square but
why you know the other terms corrections
are not compatible why distance
dominates and also why the queer fish and
of this term is what we need to be
compatible inflation so
there is a way to look at the problem
without having a potential in front on
such a thing but still open questions
namely why is it that our square time is
the only one that will contribute and
why is it that the coefficient
the coupling constant front of the.
Specific has a value in some in some
range and not in some other age.
But that's OK.
I think that the most serious
issue is the following that.
That we don't really have a full T.T.
for that that makes.
The so
what one has is more more technically
is what is called of radix
expansion this spin for
my pick you'd give you so if you want
to calculate some television amplitude
they need to give you that gives you
an answer in terms of an expansion and
the expansion is in number of witnesses so
let me just go back.
So I had shown a PM in growing from some
initial state appeared the finest It
appears initial state appeared to Finest
it appear new wood is may be created and
so did amplitudes I calculated
saying that well diameter for
one what is this what the world is this
of and these arguments we show that
each of these what exactly is going
to be up to what it finite and
if the positive cost model constant
then is also in for a finite but
what we don't know is whether this
expansion actually called religious or
what happens to the expansion so
that is the second thing that is not of.
Much much more water is a fallen I
just mentioned here that in fact
one has things like then point functions
of the guy without propagators But
again what is done is the leading
order calculation and
we don't know what the submitting
terms are we don't know if some
leading terms are not going to be
because a new wrench in the whole thing.
Is a part of a dilemma so
we don't know that out so
the basically did there is a huge
incompleteness at least as far as I can
see there is no kind of a roadblock
that just seems impossible to do and
that's why we need much
deeper understanding of how
defective field theories that seem to be
quite work quite well in particle physics.
Group Theory.
So that is here and it's really is a lot
in group really the the group that comes
up is really sad to see
which is really it's really
the the space it is really just that
that group that is coming up in the spin
formatting in the Hamiltonian approach
then you're going to kind of your love
slicing of spacetime and therefore you can
be used to see two kind of a before they
saw three because they're going to be for
the rest frame basically to do that but
here is just the local Lawrence
group that is going to.
Right so this is the.
I should say that I'm not.
OK first let me tell you
what the predictions are so
this is that these are the predicted
participations and plant has not.
Yet released data this data has
been released and this their ties
are already mentioned with provides
a better case could fit with observations.
But these are not so the statement is
under no plan can release this data
they were supposed to release them
during some of them postpone it
because an analysis that is
Lowell's is complicated and
that many many factors
are there to take into account.
So they will so the question is Is
there power suppression or not so
here's a prediction now I'm not wildly
optimistic I'm not just waiting there
because I'd suspect that the error bars
are going to be large rather large and
therefore this this operation may
be that it is suppression but
it is at such a low signal level.
But then.
There are.
In the event plan to release that data.
Just before they release data in two
thousand and fourteen December they had us
explain to them you know what one of
the products of the form responses to and
then asked that you know what should we
be doing right and it is they who told us
that in fact you know all these might be
loosing my facts and that there's a lot
but in fact if there is a fundamental
theory which explains it all of them
together then one would take it seriously
so that is why we looked at I only talked
about participation but also they missed
particular there's another open song.
And there are really very strong cuticle
constraints not easy to muck with this
thing I mean if you for example produce
a mystical anisotropy almost always
you produce such large long ocean it is of
that ruled out by the visions so therefore
the fact that they exist is what is
important to me the main thing is that we
are actually making contact I'm not saying
that this is going to be good be you
know verified tomorrow something but we
are making contact and they can come and
say well you know yes we we've got a fight
although we falsify it or well we're too
bad this is within a visionary about but
still there's a dialogue with abs of us
this is the first time I think that any
quantum gravity did such a dialogue.
Right so there is.
A black hole singularity but
the calculations a lot of detail here
are kind of very detailed calculated
calculations are done many dollars So
this is going on something that.
A bunch of us did a while ago at the first
crack at it sort of say which I was one of
the authors and none of those papers I
believe are really solid enough that this
is how things really happen but the short
is kind of hold the way they say or
do this calculations more recently the
horrible in screw up with the particular
route forgot to get completely there
done a very nice work which confirms and
as many details to this picture that
the singularity is actually the result but
if say this was the big
bang was easy because
it is quantum mechanics because you
know a special majority or even
special margin even if I'm not so
trapeze makes it that the only
thing three three dimensional classical
dictate classical degrees of freedom
whereas if you only are you a spirit
of symmetry you still have a radial.
More and therefore it's a field and
therefore the calculations are much much
harder and therefore things are not
as complete as they should be but
I think that there are many indications
that clearly I believe the singularity is
the result but exactly what happens
after that is it's not as clear as a.
Place.
Big that we know.
We go to the other side of the Big Bang so
what will be the universe before so
when we.
Cross.
From which we heard the universe.
So.
It was collapsing and
the finally was actually expanding.
And so in the collapsing US the cost
particle council matters less and less.
OK so so that is the difference
between the two first of all the but
I not answered your question so so the
statement is that if you started out with
some initial data which is kind
of random then the statement is
that they could be conscious and
then we could not have been born.
But what we're done is start with a nice
Nischelle that I would compare the two
days in us and you want it back and if you
value back then still a question would
happen that this put the basins actually
I mean can you while back systematically
The Do they remain finite or in fact do
this but the basins actually do something.
Near the beach and
the statement that we find that is but
a base is a perfectly well behaved
across a because of so in other words.
What the reason why this is awarded
is really the initial conditions and
one of the three papers the security
papers this year had to do with
his initial conditions so well some
fundamental principles I should say that
all these things are proposals I mean
they can be observationally voyage in and
searching but that is proposals so we're
going to a principle which tells us which
selects what the initial conditions should
be and if the mission conditions are those
principles one of them
is this condemnation of
Bender's as well coverage I point this
is then the statement is that in fact.
In other words it is not true
that any initial data in the past
there will be because that is what is not
true that I initially data in the past for
which there is no because each and
furthermore those initial data
are selected by some principle
that where where where proposed.