Dutch language

How to pronounce space-time in Dutch?

Full Transcript

yeah welcome everyone in this great
auditorium on this evening it's great to
hear with so many today and it's an
honor for me to stand here in
representing the 50 paid study study
Association of physics in Delft and
studium Generale Adel to present to you
our speaker of the night Eric falinda
well to you he must be very well known
especially for his alternative theory on
gravity and he seeks to find an
explanation for gravity that's
consistent with both quantum mechanics
and general relativity and it's
interesting because he's been interested
in gravity the smallest and the largest
of the universe since he was I think 15
years old if I'm correct because then he
was a TV show little toss at a low key
to the universe and he saw there his
great examples which are now his his
colleagues I think such as here at Hope
and Stephen Hawking well then he studied
in Italy EFT and he also did his PhD
there and he worked at Princeton CERN in
a second and since 2003 he's a full
professor at the University of Amsterdam
in 2011 he won the Spinoza prize which
must also be well-known to you it's the
highest science prize that you can win
in the Netherlands and today he will
take us on a journey through his
research and so it might be hard
sometimes but bear with him and after
the lecture which should take about an
hour there's plenty of time to ask all
the questions that you want to ask him
there catch books is here so wait yeah
they are shown now wait till they're
thrown at you such that everyone can
hear the question that you asked so
thank you very much for being here and
let's welcome professor Eric for Linda
to the stage
yeah thank thank you thank you for this
kind introduction and it's feels very
good to be here and to see indeed
there's so much interest in this topic I
became interested as Julie I was
explaining already in my high school
years and I knew I wanted to do physics
and a particular work on problems
related to gravity and quantum mechanics
and and indeed we have made a lot of
progress and what I'm doing now I could
not have imagined that at that time but
it seems like we're finally starting to
understand better how to put these two
subjects together because at the time
when I started studying it seemed like
gravity and quantum mechanics were
totally different worlds and they
couldn't be sort of United so the
current developments really have a new
way of looking at gravity a new way if
even looking at the universe and what
are its building blocks and I'm gonna
start out explaining a little bit why
are we changing every time our point of
view on nature why is it necessary and
it has to do with experiments with
observations but also with the language
that we're using because every century
in physics there's a connection between
what we do in terms of technology and
what we do in science we use the
language of the world around us and so
in the 17th and 18th century people knew
but mostly about mechanics of moving
objects like while cannonballs then in
the 19th century became we discovered
steam engines and then you talk about
temperature pressure and and maybe gas
flow eventually it atomic picture
arrives Rises and then the 20th century
well a television one of the the
technologies we develop then if you look
inside of it it takes particles
electrons it accelerates them and then
it lets them hit the screen and then we
get light out of this and sort of the
the forces that I use are electric
forces things like that actually that's
the language of the 20 20th century
particles forces and that is also still
today very much the way we think about
nature
as in terms of elementary particles and
fundamental forces but we live in a
different time now I mean we have
information devices I mean our our
current technology is based on what we
can store in terms of bits and we have a
different language that's being
developed and this is what I'm going to
explain is that the basic building
blocks even that we're gonna use to
describe nature are going to be not
particles or the fundamental forces
we're going to think about something
called information and I'm gonna explain
more what I mean by information you may
think information is what you read in a
newspaper but for me something more
abstract it has to do with really the
microscopic information that's contained
in everything that nature is made of
even space and time so what does it need
information I mean it's stored in bits
and this is sort of for me unimportant
what is written there you just count for
instance what how many bits you have and
that tells you how much information you
in principle can store say on a chip or
even in other parts of nature we can
count information in terms of how many
bits I'm going to talk about special
bits not just zeros and ones we also are
going to use quantum mechanics because
microscopically or actually the whole
world itself is quantum mechanical so if
you ask how does nature store
information it has to do it in qubits
not just ordinary bits and qubits can
entangle I shouldn't be explained this
here people know this very well and this
is the kind of thing that we're going to
use an encounter also during the talk so
I'm going to tell you a new way that
we're going to think about the universe
where we think about the basic building
blocks as being information this is
maybe a way of phrasing it that we live
in an information universe not an
information world the whole universe is
revolving around information and you may
wonder where is it and where are we
gonna well find it because we may not be
aware of all of this and some of the
information is hidden from us and that
actually bring me to another
concepts I mean if we have information
we don't see I mean how are we sure it's
there first of all let me show you this
you probably don't know what it is but
if I make it smaller you still don't
know it but it's the same thing but if
you look at the bigger picture you start
understanding what that was I mean it's
part of a picture that shows you now
mountains and trees and all kinds of
things that begin give names but if you
ask do these things exist
microscopically no because everything is
made out of pixels and it's only by
making many pixels together that we get
an image and that we are giving names to
objects but microscopically these things
may not be there and this concept is
called emergence that when you build
many things together you see structures
arising that and you give it names that
may not exist at microscopic level and
this is how I describe it we need to use
concepts and we observe phenomena and a
macroscopic world and it's magical
skills but they're derived from
something microscopic where the same
concepts are not well-defined and they
have no a priori meaning so we do is all
the time in physics for instance
statistical physics is a way of
explaining thermodynamics thermodynamics
uses concepts like temperature and
pressure or entropy but microscopically
those things don't exist so the the
macroscopic properties are derived by
averaging over all the microscopic
properties and so temperature can be
defined as a measure of average energy
for instance per degree of freedom or
per molecule entropy then is associated
with the amount of information that I'm
actually forgetting when I go from the
microscopic language to the macroscopic
one when I look at the room here we're
not really interested how all the
molecules are moving and we usually
don't look at that but we are interested
in the temperature the pressure those
kind of quantities but eventually you
have to also count what are the number
of possibilities that are present for
all these molecules and that's measured
by entropy and
this is the link with information
because what is an entropy it's
basically the amount of information
that's necessary to describe how all
these molecules are moving and it sort
of counts the number of microscopic
possibilities that are present and
therefore it's not an entropy that we
can really have an information that we
can really read but we can at least
count how much there is so the
connection between entropy and
information actually is due to Shen and
Shen basically said that if I have a
number of bits that means zeros and ones
but it can also be coins that you flip
you have heads and tails and if your two
points then there are four possibilities
but then you can count the entropy and
that's basically taking the logarithm of
the number of possibilities and so that
space it then it becomes in this case
equal to the number of bits so that's an
intuitive way of thinking about entropy
of course it doesn't always need to be
in terms of zeros and ones or heads and
tails I can also use dice and then count
how many possibilities I have here but
still you can count it and this is how
we associate the amount of information
that would be necessary to describe all
of these ways that these dice are being
thrown in terms of an entropy so for me
information is not as I said what I read
in a newspaper or what is really useful
it's something that I can count and I
can think about in terms of bits or as
I'll explain later in terms of qubits so
what does this have to do with gravity
I'm gonna tell you later that indeed we
have a way of understanding gravity and
it's connection with information and
it's going to teach us something about
the universe and it's going to teach us
something about how things might be
different then what Einstein is telling
us so Einstein describes gravity in
terms of curved space-time I'm gonna
tell you that underlying that there is
some information that is present and
that will actually affect the way that
gravity works so let me start with
Newton
of course you you all know that the law
of Newton tells us how the force between
two masses acts as a function of the
distance goes like one over R squared at
the same as how the surface of a sphere
would grow as a function of the distance
in a me it goes like R squared
this actually is already a hint that
gravity has something to do with this
area of a sphere sore or yeah something
like an R squared and later I'll indeed
show you connections with that for
instance with how entropy arises in
black holes it's also associated with
areas but it's basically this one over s
R squared law that is telling us that so
this law tells us very well how planets
move in in the solar system and it has
been tested very precisely if you look
at how the velocity of planets behave as
a function of the distance Newton's
equations will tell you that the
acceleration is V squared over R is
equal to GM L for R squared and from
this I can read off that the velocity
should go down as a function of the
distance and if you look at the planets
that is exactly what happens now all of
these planets behave very nicely
according to Newton's law actually the
most inner one has a bit of a problem
normally planets would go around like
this in an ellipse orbit where they have
a near point which you call the
perihelion and then there's the farthest
point but the Peary Hylian should always
be the same location and for mercury
that doesn't happen this is an
exaggeration there's every time that it
goes around it has a slight rotation and
in a century it's a lot like 43 arc
seconds I think that is so this is a
very tiny deviation but it's deviation
from the laws of Newton and you might
try and explain it by invoking or
postulating that there is some other
planet closer to the Sun Sun and that
might actually cause this deviation to
happen and this is what when people
looked for but that's not the
explanation it's not that we can save
Newton's
here this is an effect due to general
relativity so Einstein indeed could
explain what happens to mercury and he
could explain many more things in
particular also how light behaves in the
presence of gravity so according to his
theory gravity is the result of
curvature of space and time and so
objects no longer going straight lines
they go around in these elliptical
orbits and maybe small deviations from
it
that are due to the fact that indeed
Einstein's equations are not exactly the
same as Newton's equations he wrote down
an equation that tells us that in most
circumstances Newton tells us very well
what's going on but in other
circumstances when gravity gets very
strong we need science equations and
also to explain or understand what light
does in in a so fun as due to gravity in
particular light can bent and in this
picture we see that light generally we
think about is going in straight lines
but when there's a heavy object then the
light of an object that's behind the the
mass here can bend around and we can see
it but we then see it at an other
location because we would think that the
light that is coming to us actually is
coming from this star so you see
actually a dislocation or a displacement
of the location of stars and this is
called gravity well bending of light or
you can have a certain effect we call
gravitational lensing which is a sort of
a same idea that namely light bends
around and can come to us but it can
bend around if there is an heavy object
in the middle and more in one way
actually can bend this way or that way
and even go above or below and this is
an example which indeed has really been
observed where there's a galaxy far away
and there's a big mass in front of it
and the light gets towards us in more
possible ways actually it forms a ring
and that's called the Einstein ring and
this is proof that light is being bent
by gravity and can be explained by
Einstein's theory so Einstein has
explained Mercury
can explain bending of life of course
there are many more tests of Einstein's
gravity in particular very spectacular
one which you heard about which got the
Nobel Prize last year is the detection
of gravitational waves so where you can
observe that space-time according to
predictions of Einstein has ripples that
are sent out when two black holes are
colliding or merging together in the
last moment they spiral so violently
that the space-time itself gets
distorted and these ripples they travel
towards us with the speed of life and
can be detected in this interferometer
this is one of the LIGO ones and they
were in two locations while about 1500
kilometers apart or it may be more even
we're both sick found the same signal at
the same time so this is what happens I
think you can hear it can I no sound
there should be sound
No okay there is a sound of this that
allows you to hear what is going on it's
actually a a ringtone that you can buy
which is indeed the detection of these
waves so this is the Einstein's equation
and here are the ways it has been tested
and in any more circumstances of gravity
waves there was already there in direct
evidence of gravity waves from binary
pulsars bending of light and what
happens with Mercury and many other ways
so you might say well this theory works
and it seems to work in many
circumstances but does it work in all
circumstances I'm gonna actually tell
you something about larger scales and
here you might say well it should work
as well because we don't know anything
else
Einstein's theory must be right so we're
gonna look what it does but does it
really look the same so when you look at
galaxies they look in a certain way like
a solar system in the sense that most of
the mass is in the center if we look at
the Stars the many more in the center
and you can think about all these stars
as going around in sort of circular
orbits where you can look at each of
those slices and ask what is the
velocity you can measure this by by
redshifts and then you see as a function
of the distance you would have expected
from the same way that planets behave
namely that large this since the
velocities go down that would do
something like this but this is what's
being observed
now you can have true conclusions how do
you say gravity works in a different way
or if you assume that Newton's law
should work there must be something well
explaining this difference well what's
happening here is that the stars are
moving much too fast and they would well
fly out of orbit
if you rotate too fast with bit not
enough force and so there must be
additional force putting pulling it
together otherwise we cannot explain why
these stars would go so fast and so
there must be additional gravity so this
is another picture of it so this is
what's called a rotation curve
so this is the velocity and this is
again the distance and this is what you
would expect and this is what we observe
actually in most of these galaxies the
following thing happens instead of going
down the velocity stays constant is
called flattening of the rotation curve
and there's a big difference between
what is expected and what's being
observed and there must be more mass
actually if you want to explain this so
this is indeed different from this
equation actually you can determine what
should be the additional mass by looking
at the velocity and using this equation
and this is what led to the idea of dark
matter it's a hypothesis it's very much
like what a planet that was assumed to
be there namely it fixes Einstein's
theory because we say there must be more
mass and we would look for it and must
be some particle that is forming a cloud
sort of a halo it's called around the
galaxy where the gravitational force
which is needed to put to keep the
galaxy together is required is obtained
from the additional mass that's in these
particles these particles cannot be seen
here they're blue but that's just an
artist's way of showing it but the
particles have no interaction with life
they should be only gravitational if
have only gravitational forces
well people look for it in accelerators
they look for it in the detectives under
the ground and so far nothing has been
found and so you might wonder is this
the way indeed we have to fix our in
science theory or is there another
explanation
and so I will explain there are more
things we don't fully understand in
cosmology there's also something called
dark energy I will return to that later
so there will be questions that we need
to pose and need to answer also well at
large skills that might actually tell us
that something else is going on then
what Einstein might have written down
but for me the main motivation actually
of main indication that Einstein's
theory might work differently comes not
from these observations but also from
theoretical
well developments I mean indeed the work
of Hawking which is the one I already
became interested in his work was on
black holes in particular and on Deedle
cosmology but black holes is one of
those topics that we theorist use a lot
to learn more about gravity so what are
black holes these are predicted also by
Einstein's theory this is where mass is
put together by in such large quantities
and so close together that light cannot
even escape
I mean gravity becomes so strong that
from a black hole there is no escape
when you go too close to it there is
namely some imaginary sphere around it
people they store ricin that if you go
inside that sphere then you well you
have to go faster than light to escape
and says nothing can go faster you
cannot get out and light cannot even get
out and this is why the name was given
black holes so we know that mass goes in
so we know the mass of a black hole
black holes can rotate but otherwise we
have no information of what's inside the
black hole so everything we throw in
disappears from our view and so black
holes are really objects that we can
only study from the outside and wonder
what went in so this is what it looks
like in terms of the space-time so a
star like the Sun would have a curvature
of space that looks like this it sort of
makes it dent you can think about this
as a lot of a rubber sheet where you put
a ball inside and then it sort of bends
through over and so it has some dent in
it and they and the more mass the more
you concentrated the deeper it goes and
in a black hole there is a sort of a
funnel funnel there's a hole coming in
that goes all the way to the bottom or
at least it goes so deep indeed that you
hit this imaginary sphere where's the
horizon so every all the matter goes
behind that horizon so this is how we
should think about black holes is naming
it all the matter has sort of
disappeared and only what's left behind
what we can see is the space-time the
curved space-time of
the black hole itself so what would it
be if we would be in a neighborhood of a
black hole here is the earth and this
would be a black hole and this is sort
of what you would see it sort of looks
like the earth is being distorted that's
not actually happening this is the light
that we see namely the earth is just
rotating around the black hole but the
light is coming towards us from all
directions you in the way that this
gravitational lensing worked and so we
see the earth sort of going in this
circle but of course it's just rotating
that way I can also show you how what it
looks like when we fall into a black
hole and then I want to remind you of
this bending of light so we're going to
do it later I show you a little clip of
how we move inside the in the
neighborhood of a black hole the rise in
this is red line we're going to look at
the black hole which is here in the
center and we're going to look at the
light coming towards us so the light
here is some background which is the
galaxies but this is gonna move we're
also gonna watch and what happens with
the clock because black holes have
another special property that not only
light cannot come out also time goes
behaves very differently so Einstein's
theory does not only change space and
curves it also the time goes very
differently in a sense that actually
clocks starts looking are going slower
when you go close to the horizon
actually it really stops even when
you're on the horizon and so we're gonna
watch this when we look at the movie so
here's the same picture again so we
start out from this distance and now
we're gonna fall and the green region is
where we can travel safely you go around
in these closed orbits when you would go
closer here you would need a rocket to
get well stay safe but when you get to
orange there's no way to get out because
then you will fall into the black hole
which is where you have entered the
black hole so here we're getting closer
we see also the horizon eventually
that will be indicated with the red
lines the north in the South Pole our
little distorted because of the bending
of light here we see indeed the light
there's one distance where light itself
can even go in a circle around it so
light would even be captured by a black
hole and here we indeed see the clock
going slower and at someone want we
cross the horizon and then we see indeed
the last sort of light coming from
outside and nothing is shown what's
coming from inside because basically we
don't know so eventually we hit the
singularity that's what's in the center
so the center of a black hole is where
curvatures is so strong that we really
don't know well what happens there
because even Einstein theory breaks down
but most of the interest actually of
theorists is on the horizon and so that
horizon I can actually show you this mu
clip once more most people want to see
twice so this is the same picture again
and as I said I mean there is a
singularity inside but the horizon
itself is a very interesting place
because of the way that the time indeed
seems to stop from the outside but when
you fall in yourself you actually don't
know that you're crossing a horizon I
mean the space actually looks pretty
normal
yeah you get strong gravity but it's not
like there is something really infinite
or something no there's a really normal
space so you could fall in the only
thing that goes wrong with you is when
you hit a singularity or when the
gravitational field becomes really
strong that it pulls you part but the
horizon itself can be analyzed in a very
similar way as we analyze other parts of
space-time and isn't it but what's
bekenstein and hawking did this is a
more precise picture indeed of this
space-time around a black hole so a
black hole has the property that there
is one distance which we call a rice and
here we draw the space actually at this
as if it's two-dimensional so the rice
and normally it's a sphere but here
looks like a circle and when you would
emit light it would normally go in all
directions but in this case when you on
the horizon
it actually goes inward and this is how
you would indeed fall in if you cross it
now back in stand Hawking we were
worried about the loss of thermodynamics
in a particular what happens with the
entropy of objects that you throw into a
black hole namely this entropy is
disappearing from our view it represents
a certain amount of information I told
you this and what happens to that
information well if we throw it into the
black hole disappears from our view and
so you might say well this entropy
disappeared and it you can do thought
experiments that allow you to actually
generate work by throwing in this matter
with all the entropy in it and then you
would even have a way of generating work
and actually violate the laws of
thermodynamics because the entropy would
not go up I mean it would actually go
down and so the only way to save this
was to associate a certain amount of
entropy also to a black hole now this
was the idea back in stein and Hawking
then came along and well he first didn't
believe it because if you have an object
that has a mass which is also an energy
equals MC squared and it has an entropy
and it also should have a temperature
and Hawking was not convinced that this
would be possible until he realized that
he could actually calculate it and this
is how he found the famous formula so
actually he found actually that black
holes emit radiation I should first
explain that he actually found indeed
that it has a temperature it's called
the Hawking temperature and he found
that by quantum effects because both of
these bekenstein
as well as Hawking reasons that we
should use quantum mechanics to explain
this amount of information associated to
the horizon and indeed also the
temperature involves quantum properties
of both particles and enough space and
time so in particular particles in the
vacuum can exist even in the vacuum
normally you think is empty because of
the quantum uncertainty relations the
vacuum contains
we call quantum fluctuations means that
some particles in their antiparticles
can be present for a very short time and
then they usually recombine again it is
this picture but when there is a horizon
what happens and this is what's what
hawking showed one of the particles can
disappear and go inside the black hole
and the other B is being emitted and
comes out as a particle that we can
detect and it has a certain temperature
certain this radiation it's like
blackbody radiation with the temperature
set by the acceleration actually at the
horizon so these are the formulas that
Hawking derived so the temperature is
given by the acceleration the
gravitational acceleration that's G at
the horizon so this formula is just the
same formula that you know from
Newtonian mechanics this is the
acceleration at distance R M is the mass
of the black hole the radius by the way
is set also by the mass I mean this
horizon distance we call this what
shield radius is also determined by the
mass bigger black holes actually this
radius becomes larger is actually
proportional to the mass but if I
calculate this and put it in this
equation I would get the temperature and
that is indeed the the Hawking
temperature that that Hawking calculated
I said it has a temperature but also an
entropy and that formula is also famous
and it's known by the names of
bekenstein and Hawking here I showed in
a picture I'll show you the formula in a
minute so we think about entropy as
information so zeroes in once and you
can may ask well how much information is
then stored by a black hole it's given
by the area of this surface of a sphere
and namely you have to measure it in
planking units very tiny units and then
if you put zeros in once on all of those
locations you could store an amount of
information and that amount of
information is the entropy or the
information that that black holes carry
and in a way it hides the information
because we cannot see it that we can
still count it in terms of an entropy
here it's explained how larger this is
10 to the minus 66 square cent
meter so it's a very tiny surface and
this is neat what the formula looks like
so the entropy which is called s is
equal to the area of the horizon divided
by the units bye-bye well the Planck
scale and this is written down in
natural units containing Newton's
constant Planck's constant and the speed
of light and if I would have all the
unit's right actually entropy has the
dimension of Boltzmann constant so all
of the constants of nature basically
enter in this equation and so this tells
us how many bits if information is
associated to a a black hole and this
was a very important discovery actually
it led to met many discussions because
the question was well does this mean
that we can still keep track of this
information and can be retrieve it back
in sign repertory in particular Hawking
actually argued that information is lost
in the sense that information that we
throw into a black hole cannot be
retrieved and it would violate even the
laws of quantum mechanics so Julia
already mentioned the people that I
watched on this show were Hawking and it
hoped and feared that host actually when
I started studying started worrying
about this problem and he started
arguing with Frankenstein 3 we're
talking about this information lost
paradox is it's the are the laws of
quantum mechanics obeyed yes or no
because if it quantum mechanics is
obeyed actually quantum mechanics it
works in such a way that it doesn't
really destroy information we call this
unitarity you mean probabilities have to
be preserved but also information that's
in a quantum state cannot simply
disappear so in order to save quantum
mechanics we have to understand what is
information represents and how it well
it may even retrieve it
because when the particles are being
read radiated out the information has to
be sort of released from the black hole
and it's up to this day that people are
still discussing it because it's very
well hard problem to solve but it
teaches us a lot about how space-time
how gravity works and what the link with
information is in particular indeed that
is
information is stored sort of on areas
on the surface say of a sphere these are
some more complicated equations actually
these I show these equations because we
actually use them a lot and what they
show is that the gravitational equation
is the one that follow from Einstein's
theory actually they are basically the
Einstein's equations so what I've shown
here is the formula that tells you how
much does the area change when I change
the mass of a black hole it's determined
by the acceleration at the surface of
the horizon by this equation so you
might say this this equation follows
from actually Newton's law or even
Einstein's law actually you might say
this is of Einstein's equation it's a
way of summarizing Einstein's equations
for black holes and therefore you might
think it's a fundamental equation but
when we make these substitutions namely
we say the area is the entropy and the
acceleration is related to the
temperature then this equation is the
same as that equation and that's the
first law of thermodynamics and that is
a law that we can derive we can derive
by thinking about statistical mechanics
and understanding what this entropy is
we can derive this equation so if we
understand this entropy we can derive
this equation by statistical mechanics
but then we have derived Einstein's
equation and that's the idea of what's
called emergent gravity indeed that
gravity itself can be explained
microscopically once we understand what
this information represents and how we
then can derive these laws because then
we derive Einstein's equations from a
more fundamental microscopic picture in
the same way that we have explained the
laws of thermodynamics by thinking about
atoms and the way they behave
statistically so that subject has been
actively studied now in particular the
last number of years I'm going to tell
you a little bit more about what is
going on there
but this is really the way that we think
that we have found a crack in a science
theory that there might be a way of
thinking about gravity in a different
way than then that Einstein told us by
thinking about the microscopic structure
of space-time not in the language of
particles not directly in the language
of forces but thinking about more
fundamental building blocks in terms of
information and in particular its
quantum properties so a toast indeed was
one of the first people to start
thinking about the implications of what
we learned from black holes and he
already made a very important what
conjecture are basically stated the
principles called the holographic
principle that there's not there's no
way that in any region of space you can
have more information than what is given
by a black hole and means also that this
amount of information couldn't cannot be
larger than the area of the surface
around it in planking units so if I take
this big lecture hall and I ask what's
the maximum amount of information we can
store here you might say I put a very
big computer here with a smallest chips
possible but that information can never
exceed what you can put on the boundary
in terms of Planckian bits in in terms
of its area because if you would you
basically would form a black hole as
large as this room so that's the state
of maximal information and there's no
other possibility so this was an idea at
that time but it has been made much more
precise and actually being realized in
string theory I'm not going to explain a
lot about string theory but all to say
some other things later I want to tell
you a little bit about how I started
thinking about these ideas some years
ago in particular indeed the idea of
what's called now called emergent
gravity can we derive gravity by
thinking about this information can be
indeed derived Newton's law for instance
and by assuming that indeed all the
information associated with a part of
space-time is counted or stored on the
sphere of a surface around it you can
actually do so you don't need to
have much well math or even there's some
steps you have to do where you make some
assumptions but then you can actually
derive Newton's law actually it's in a
paper I wrote on the loss of Newton and
on the origin of the loss of Newton and
of gravity where I derived Einstein of
sorry acted Newton's law by thinking
about a thought experiment indeed by
asking the question what is the amount
of force that you can derive by thinking
about information stored on a on a
surface and ask well what happens when I
put a massive it close to it actually
I'll show you the equations in a bit
there's actually this slide I should
have shown so there's actually a
calculation I'll go a bit to the steps
there was one assumption about where I
say that the amount of information is
need proportional to the area that's
this equation I'll call that area
measured in terms of Newton's constant I
have to assume that there is a force law
that actually comes from the change of
entropy is called an entropic force you
can calculate that change of entropy by
a very simple experiment thought
experiment that tells you that there's
only one bit of information associated
to a shortest displacement anyway I'm
not it's not my idea to go through all
the steps but it fits some simple
equations that I could derive Newton's
law so this is a way in which the idea
of having gravity come from information
actually could be realized and since I
wrote that paper a lot of work has been
done and actually we know a lot more now
and we have made well progress even in
deriving Einstein's equations from
quantum information so what is this
information we want to know more about
what is the information associated to
the horizon and what kind of information
is it and as I mentioned string theory a
big subject that that I'll just have to
skip because of time actually has
realized this holographic
principal but it also has led us to
conclusion that we can indeed explain
gravity but the information we have to
use is called quantum information so
it's not just zeros and ones as sort of
all these pictures shows it's it's
something different associated not to
bits but to qubits so let me explain a
little bit about that development so
what is quantum information there we
have to distinguish indeed a bit from a
qubit a bit it can be zero and one but
qubits can have super positions and you
can either think about an electron with
a spin up or spin down or just a state
that is in between a 0 and a 1 so in a
picture a bit has only two choices if it
would have a certain probability of
having 0 and the probability of having 1
you would have a sort of like a
parameter that's the probability but
actually in quantum mechanics we also
have complex numbers here actually if
you then count all the possible ways you
can put 0 & 1 together they actually
form a sphere it's called the Bloch
sphere so I'll actually make a picture
of a qubit as a little sphere instead of
having only choice hero and 1 we have
all kinds of choices in the middle so
this would be pure 1 and this is pure 0
but then there are other things in the
middle that formed this qubit and this
is the way the reason actually why we
can store much more information on a
qubit or actually do even better
calculations than in normal bits the
other property that makes qubits very
useful is called quantum entanglement
where you have to probe the problem or
the possibility of measuring something
in one location and then the outcome of
the measurement which is well
probabilistic actually it's not
determined directly but it gives you one
outcome it determines the outcome of the
other of measurement and that is called
entanglement so this is what I meant by
this notation there's a some way that if
you measure 0 on 1 the zero must be on
the other or if you measure one that's
here as well or in terms of a quantum
notation it looks like that the people
that thought about quantum entangled the
first time or Einstein Podolsky and
Rosen already in the 30s a long time ago
and they worried
about it because it had strange action
at a distance
but it's only much later that we start
realizing the importance of what they
did actually in the sense that
entanglement was not recognized in the
beginning is very important but later on
actually in recent years this has been
well the most important thing about
quantum mechanics and this kind of state
is therefore called an EPR pair named
after Einstein Podolsky and Rosen so
we're gonna use this kind of language
also now to think about these
information bits that are associated to
horizons and to to black holes and even
to space-time itself so we're going to
think about entangled qubits and I'm
gonna draw a picture of it so this was
one qubit an entangled qubits can be
thought about as two qubits that are
connected by a little line because
actually the measurement that you could
do on one determines the outcome on the
other so it's something like a glue like
the way we put molecules together we can
actually put qubits together by
entangling them so then what is this
information the answer is entangled
quantum information and I could have
known this from the from the way that
Hawking did his calculation so Hawking
there is calculation by thinking about
how in the vacuum the pairs of particles
are being produced a particle and an
antiparticle but if they are being
produced in one stage since this one has
spin up then this one must have spin
down so they are actually entangled and
so this is the way that indeed the
horizon entropy is being built up
actually from entangled particles
because even entanglement by the way you
can count how many of these EPR pairs do
I have so in this EP R pair I have one
bit here and not a bit on the other side
that are being entangled with each other
so I can count how many bits are
entangled so that's an entropy and this
is actually a more technical way of
showing it is actually the calculation
that hoping that Hawking showed that
there is some energy eigenstates on the
left and on the right which have a very
particular way in which they are
entangled so this is what the horizon
looks like in special relativity and
then you have sort of two states on the
left in the right this is
just to show you that there's really
some meaning to the entanglement because
this notation you should compare to what
I had here and then we can basically
count how much entanglement is in this
actually it's given by the area of this
horizon so this idea that entanglement
has something to do with gravity even
has name now and the name actually goes
back also to another paper of Einstein
around the same time he worked on
horizons of black holes is this picture
if you have a black hole I showed you
there's a little curvature and there's
some some tunnel where you go through
but actually when you extend the
Einstein equations and look at the full
solution of the equations actually
there's another space that opens up
where the black hole forms a wormhole
that exists for a certain amount of time
it's called the bridge actually it's
called einstein-rosen bridge because he
wrote that paper together with Rosen the
same Rosen from einstein-podolsky-rosen
and they found this solution of course
they didn't know anything about emergent
gravity and so on but now in our present
day we have actually made a connection
between this entanglement idea and the
way that space is sort of built in this
way and this is called ER as EPR because
it's basically telling us that indeed
the entropy that we measuring here is
and thangam and entropy and it's
counting all these qubits and we sort of
gluing space-time together through
entanglement this is a big developments
going on in the u.s. not now it's called
it from qubit where we built everything
from information qubits even space-time
itself and we have a different view of
thinking about it so now I have to hurry
a little bit because I want to go to
back to the questions I raised in the
beginning and hopefully explain a little
bit what has to do what we can learn now
about these problems that we are
observing in cosmology
from this idea so what is the idea and
what's the conclusion that I've given
you sort of up to now is that indeed we
can think about space and time as
being sort of derived or build up from
entangled quantum information in gravity
comes about but can we think about links
with observations so I told you about
the observations in galaxies that we
don't understand and actually all the
observations that are associated to dark
matter in total this is a way we have
already determined that there's more
gravity out there that then we can
observe this is called a weak lensing in
the sense where people can measure how
much gravity there is by looking at this
bending of light and they've determined
that there's a lot of gravity here but
most of the matter is actually in this
region and so we have seen sort of well
locations where gravity is there without
having matter so this is where where
must be something well like dark matter
dark matter also forms an important role
in the structure formation in our
universe so people believe in this a lot
but now if you look at what the universe
is made of the ordinary matter that we
see is only five percent of what we
observe and dark matter according to the
current observations of particular the
Cosmic Microwave Background is about 25%
but most of the energy in our universe
is what's called dark energy so this is
95% we basically don't understand and we
wonder what is happening there so this
little white light of a sorry yellow
line is actually the life that comes
from the microwave background the
earliest radiation we can observe and
there are photons and that's a very tiny
number but if we ask according to our
current theory where most of the entropy
is sitting in our universe it's not here
it's not there it's not there it's
actually in this yellow yellow blob
blind people don't assign any entropy to
dark energy they call it the
cosmological constant they basically
forget about all of this and our current
theory only describing this a little bit
and this is where we have I think made a
mistake and I'll tell you a little bit
what the idea
so the way that people observe the
universe we do it from our Center we
look outwards and we see this radiation
coming from large distances because when
you look further out actually you go
also back in time the universe is
expanding which also makes clear that
things are moving away from us and
there's a farthest distance we can look
and in in a way that gives us just like
four black holes also a horizon so to
think about it this way if things are a
certain distance they move away but with
us from a with a certain velocity but if
we go further out eventually there will
be a distance when it starts moving with
the speed of light and that means that
the light cannot travel towards us
anymore and that's a distance we call
the horizon of our cosmos so in
cosmology we can describe this in terms
of Hubble's law which tells you indeed
that the velocity goes with the expect
with the distance and the constant
influence we call Hubble's constant and
so the distance where this velocity is
equal to the speed of light it's called
the horizon distance and that's measured
in terms of this constant age now why do
I talk about this horizon this horizon
has very much the same properties as
black hole horizons and I told you
horizons have information so we can you
see a sort of an holographic idea of how
much information can be put inside our
universe so if we would think about our
universe is a very large computer where
we store a lot of information how much
can there be in there well not more than
the horizon of this area of this the
area of the horizon
and that actually tells you exactly how
much information is contained in the
universe so I'm gonna actually tell you
that this may affect things that are
going on in inside because I actually
want to explain where this difference
comes from so the idea will be that this
information associated to the horizon
actually will not be just sitting on the
horizon but also in the center Oh
actually over the entire
universe so the following observation I
want to explain I told you that galaxies
rotate but then the velocities don't go
down they stay constant but this happens
at a particular acceleration always the
same value for all sizes of galaxies so
this is an acceleration according to two
Newton's equations but I can express the
value where they start happening in
terms of the Hubble constant
if I multiply C with the Hubble constant
with the speed of light exceeds an
acceleration and this always happens
when this so did the when the
acceleration drops below this value this
actually when this starts flattening and
this seems like galaxies know something
about the Hubble constant actually know
something about even the dark energy in
the universe so neat this is the picture
again so this is where this galaxies
sitting and this is our cosmological
horizon
it had this distance this size and it
has an area that we can calculate is the
area of a sphere and we can calculate
the entropy we can also calculate the
temperature according to Hawking it's
also given by Hubble constant and I say
this entropy and temperature are
actually due to the positive dark energy
and actually are carried by the dark
energy and they fill the entire universe
I think I need to both okay all right
five minutes okay okay then then that's
about what I need so this is where I
write the same equations as I had for
black holes a temperature and an entropy
and it's a entropy we have not
considered actually it's a very low
temperature it's also a very low of hot
but it's a very high temp interferes who
say this is a number which is called
about 10 to the 120 well the amount of
entropy that we have used for say
photons is about 10 to the 90 so most of
the entropy is actually sitting here and
X is going to change the way I'm gonna
think about these galaxies here are some
pictures of phenomena which look very
similar you probably can recognize that
this is the galaxy this is hurricane
is the whirlpool the reason I showed
these pictures is that here we have
water around it that's whirling we see
only the form here we have air going
around and we see only the clouds but we
know that there's something in the
middle that makes this happen here we
assume that it's just space time and
that this is rotating without anything
around it because it's empty maybe it's
not and that's actually sort of the
analogy that I want to make here I want
to make you tell you not a thing I mean
we have been observing the universe for
a very short amount of time so if we put
the entire age of the universe in one
year humans came into existence one
minute before midnight on New Year's Eve
and the amount of time that we've been
observing the universe is about a
fraction of a second but we've concluded
a lot of things about what happened in
that entire year but this is not always
possible I want to do one experiment
with you
if I succeed because it's a little bit
of tricky
they'll let me actually first do it this
way this is a bouncing ball and I can
calculate that it bounces and it bounces
every time in the same height so I know
the theory of this which is elasticity
I'm gonna do this again and it's going
to do exactly the same thing but the
material is slightly different I have to
make it round
actually does exactly the same thing but
if I put this here and I wait this ball
will stay round this one will strange
actually it's silly putty it's actually
a material out of made out of polymers
and if I wait long enough it will start
flowing the only way I can notice is by
waiting if I would have measured it only
by bouncing I would have drawn
conclusions I would have developed a
theory from of this thing which is
identical to that one that the physics
is very different because we have to
observe it very very long time so if our
universe has properties of debt we have
not been able to even test this because
we have made observations for a very
short amount of time and actually this
is the analogy that's quite precise and
so the picture that I showed you in the
beginning about a universe filled with
information that information is actually
the information that I associate to dark
energy and it's filling the universe I
know exactly how much there is because I
know the size of the horizon I can
calculate the information density
there's also an amount of information I
can calculate associated to mass
actually this is something a calculation
that bekenstein or did it already a long
time ago and I can compare the two and
then I can actually explain that
something starts happening exactly when
these rotations the curves are changing
actually this is a paper I wrote last
year where indeed I I made a calculation
of what happens when mass is present in
a in a universe with dark energy or
without and there's a lot of difference
in the sense that the dark energy
actually contains much more information
and you get sort of a back reaction
which is due to an elastic force
actually the mass is very similar to
what happens in this material and I can
derive an equation that actually
explains exactly this behavior it
behaves effectively as if there is some
additional matter but exactly some
additional force that's pushing the
matter back so this is actually what's
what's being indicated here is that
there is actually an additional force
due to the fact that the matter actually
pushes away
energy and that force effectively
actually behaves like dark matter and it
explains these flattening rotation
curves it can be compared to data
actually this is measurements of this
relation that I found so what is plotted
here is actually the acceleration that
is observed so the acceleration that
observed is this one and the mass that I
put here on the right hand side is the
Stars so I've not put in anything of
dark matter so but I can derive the
acceleration here from only knowing the
barians the Stars and then I can explain
this rotation change of these velocities
and this is even actual data that showed
the same relation its context has a name
it's actually this equation it's called
a dual offici relation or mass
discrepancy acceleration relation and
there's also measurements that that were
happening were done in enlightened by
Maha Brauer using well not strong
Lansing is where your bending of light
she looked used weak Lansing is where
you sort of distorts background galaxies
you can figure out the gravitational
potential and she found nice agreement
with the predictions of the theory that
I wrote down actually are the blue lines
and they fit the data very nicely
there's unfortunately some error still
in the data but that hopefully will be
reduced so this is where to make clear
that this theoretical it is actually
connect to data and there might be some
obvious observation of confirmation
because this is still sort of after the
fact you might say well I knew that
these things to behave like that so the
challenge will be to make a prediction
that has not been verified but then you
can indeed test things in our universe
and so this is sort of the last picture
one a sort of and leave you with is that
my way I view that we have sort of
changed the view of our cosmos is that
our normal language of matter forces and
space-time is one that a sort of 20th
century we have sort of changed language
where we won't unstained things like
dark energy in dark matter
but in order to explain it we have to
indeed understand how these things
emerge and then suddenly you sort of
find that there's much more information
present which is sort of impressive in
this dark energy and can explain the
phenomena that we associate with dark
matter so this may be a way of sort of
visualizing the the ideas have been
explaining thank you
yeah thank you very much for the show
thank you for this very interesting talk
and I think it's actually said that we
you and started to look at the universe
so late
maybe we need generations more to
understand that we actually may be a
fluid and I think there are many open
questions that's you would still like to
work on that
I think it's first time for questions of
you to ask do professor Felina and the
catch books will go around so who wants
to start up or there's already a
question you're in front maybe you want
yeah
hi I just wanted to ask about something
that is there any super intelligence
that is controlling everything and it's
such a basic question because I'm not
from cosmology but it's such a basic
question that how the universe existed
and how our how close are we in knowing
the theory of everything so it's it's
maybe two question two questions I think
like kind of related I have to say that
I think it's already surprising that
we've come come this far as humans to
understand our the universe around us
but it's partly to do with the fact that
we are very good at making things
abstract in equations that we can handle
but in doing so we ignore a lot of
information
I think we're smart but I don't think
we're infinitely smart so for me the
idea that we can have a theory of
everything that really explains
everything is sort of hubris in the
sense that I don't believe that
are we the only intelligent creatures in
the universe I don't know I don't think
so but I cannot prove it but I don't
think we need to assume anything about
that does the universe itself as an
Intel heaven intelligence that's or the
other question you're asking I told you
there is a lot of information in the
dark energy that are no idea of what
it's doing or what is happening there
and it might have some collective
behavior that you might define in some
way
but I don't think it's important for us
I mean so I I don't even want to go into
the direction of religion or this kind
of thing because me that's philosophy
what I can do with my equations is only
estimate how much information is there
what is doing and for us that's enough
and so I don't think that that question
is part of what we need to answer as
physicists thank you thank you there are
also questions in the back I don't know
where the other catch books is there's
already yeah yeah hi my question is how
do you measure or calculate the massive
black hole that you mentioned in through
your equations how do you measure and
calculate measure or calculate the
massive black holes one of your
equations are the mass and the area
relation of a black hole you want to
know the relationship between the mass
and the radius or something how do you
you mentioned the mass of a black hole
right well the mass of a black hole is
something that you can measure on the
outside because the gravitational field
of a black hole is far away the same as
what would follow from say Newton's
equations even so if you measure so how
do we measure the mass of a star we look
at the planet nearby and then we look at
the orbit there's a direct relationship
between how fast that is and the mass of
the object in the center so we can do
the same thing we just determine the
gravitational pull of the black hole and
that actually tells us what is the mass
so actually they are close to doing this
for a object in the center of our galaxy
there is a big black hole and another
star is moving closer and what they're
gonna do is actually look at how it
behaves and one of the things they're
very excited about is that they now
discover this star has no companion we
can do very precise measurements and can
even determine the corrections to
Newton's equations there but one of the
things we determined very well therefore
is the mass of this object it's just by
looking how other objects in the
neighborhood behave okay thanks then I
don't know where they get your commands
to here front are some questions in the
back there more thank you
so we're here
you said you approved the Einstein's
equation by using analogy to entropy and
probability concepts is it ironic that
Einstein himself would have said that
God doesn't play dice
I still think that Einstein would have
liked this way of thinking about gravity
if he would have lived nowadays it's
true that his way of thinking about
quantum mechanics and the fact that he
tried to discredit it by thinking about
entanglement that had sort of backfired
in the sense that and thing among now is
being used everywhere in sort of almost
you as a proof of quantum mechanics that
it works the way that people say so
anyway I think Einstein was visionary
and he had many clever ideas and many of
them still come back and I don't think
he would be unhappy if he would be still
alive and Senath well there's maybe an
interesting addition is that I tweeted
this lecture today and there's a picture
of you I think where you have your your
hands to the back so people said oh it's
so sad that it's a lecture another fight
and then people started to make it epic
rap battle do you know between you and I
always I stand actually so they appear
so now maybe that's interesting to read
afterwards it was pretty nice I think
you won there's a question here in the
middle and okay so you told us that
information is stored in zeros and ones
and then you told us that it's probably
stored in qubits but that's still
two-level system it's still in some
sense discrete why is it encoded in the
two-level system why not in something
else entirely I mentioned already dice
as a very different different way of
doing qubits bits so of course we don't
notice that it's two-level systems but
if you want me to use cute Ritz or
anything of that sort I'm doing
something arbitrary eventually it's not
that important and I sort of compare it
to the way that people serve first
thought about atoms I mean an atom there
are many atoms that we know but in order
to derive thermodynamics any any model
for that will do so for us it's not
important where it's two-level systems
of our other level systems we just can
still count how much entropy is in there
so they
is a definition of entropy that's
independent of the fact that it's bits
or something else
there's already the kitchen right there
yeah yeah thank you for the lecture I
had a question you talked about multiple
phenomena across many scales you talked
about the whirlpool you talked about the
cyclone and then you showed us a galaxy
and then you asked us if the physics
behind them were similar you also talked
about how the physics changes in scales
from say the ones we see as properties
of air properties of gases to the atomic
scale so do you think the physics of
larger bodies such as the cosmic bodies
may have entirely different properties
that we cannot see because we are quite
small is there something else to that so
people ask me I mean let me answer it in
the following way so what I know is that
indeed the physics at large scale can be
very different than what is short scale
so the predictions of this theory is not
gonna tell us anything about gravity
that works differently here at Earth so
in order to measure that we really have
to go to these large scales but to
understand what is going on we also have
to have a microscopic understanding I
mean this is also with thermodynamics we
have to know sort of that there's an
atomic picture but then we can derive
the effect of physics at large distances
and it's true that different scales
generally don't talk to each other very
much but we can observe the effects say
like in galaxies and so on of this
large-scale dynamics without actually
having to do the experiments here at
earth we just observe what's happening
out in in large distances and and just
to give you a slightly other example I
mean in order to understand what's
happening in this material I also have
to understand what is made of and what
the properties are at very short scale
so there is a way in which the short
scale physics does affect what is
happening at large scales as well
it's very good than image there's just
there yeah hi I you told us about the
fact that your your result the your
theory works well with results we have
now but you know but any promising oh
sorry oh maybe you can stand up then
it's easier to see oh do you oh yeah you
told us about that blend credibility
your theory you'd need some more
promising predictions that could be
proven true are there any promising
predictions you've thought of so far or
anyone else's thought that we could have
could test in the future or in very far
future I have some ideas I mean they
have to do also with developing the
theory further I one of the things that
need to be worked out which is important
for what what dark matter now does I
mean dark matter has been used in
structure formation in explaining what
happens in the CMB so I have to do
calculations how to explain this using
my theory and then see if there are
differences between that and what dark
matter will predict so there's one
problem with that first of all dark
matter is not a very precise theory in
the sense that what people can assign
many properties to dark matter that
makes it behaves in all kinds of ways
and that's been used a lot to explain
any discrepancy that people see so you
are fighting with a theory that is
almost morphing itself into a solution
every time but you have to make a very
precise prediction which I'm not going
to do now because I feel like I have to
develop a theory first to the level
where I know exactly what's coming out
of this because as I make one prediction
after the other without well being 100%
sure I should do this so no I think that
we have to wait and one of the questions
I'm wondering about is actually the way
that dark energy behaves it behaves as a
function of time so I'm actually quite
excited about data that are showing that
the Hubble constant nowadays and what
would be predicted from the Cosmic
Microwave Background actually have a
discrepancy other things about cosmology
that starts to sort of become a little
more troublesome I think there may be
ways in which this theory can do better
but we still have to wait and and and
develop a theory to the point that we
can be totally sure that we we have a
fool complete theory thank you
the other case focus there maybe you can
stand up let's easier to see whose yes
hello so my question is if the theory
would be correct
I for my brain it's a bit too hard to
understand all the implications but
would there be anything we notice in
daily life that would so for example
once we understood satellites then we
had it had implications for phones and
our stuff so does it have any meaning
for things on earth yeah I mean like I
mean here I think the chance is very
small but I think we have seen other
examples in science where it was not all
totally obvious these implications may
come centuries from now I don't know
it's certainly not my motivation to do
it that way and it seems to me actually
surreal - did the answer I gave before
that the things that I worry about which
have to do with more cosmological skills
are not gonna be immediately relevant
for what we experience on the air they
let except for one question I mean I
haven't shown some of the cartoons I
sometimes show in public talks which is
why are we doing this and it's one of
those questions that I think everyone
wants to know eventually is where does
the whole universe come from that
question is now being answered using the
theory of the Big Bang and it may be
something that well you can think about
so I think that when we know more about
our origin of the universe and things
like this this is something that
everyone can be curious about and in
that way it may affect more people than
just the scientist I mean this that's my
motivation for doing that is very much
more motivated by these big questions
than making things that immediately are
applicable for our our daily lives
maybe yeah the theoretical physicist
meets the applied physics students
yeah it's of course also something that
the students here in definitely think
more about yeah we have the great catch
books which is there yeah please stand
up it's a really in the middle yeah
hello thank you for the lecture I have a
question you considered the outermost
sphere of the observable observable
universe as the surface for your
information calculation so my argument
is is there a possibility that if there
is something outside then outside the
observable universe then there would be
a little more dark matter but then again
if your equation is actually satisfying
with respect to the current
gravitational observations then in that
case we are saying the observable
universe is the end of the universe is
that true well this is a still a debate
I mean I told you something about the
horizon and what's happening there Eva
for black holes people don't know
whether when we're on the outside where
they we should be talking about what's
going inside yes and no so I say the
same thing for our cosmological horizon
it's really part of the universe that we
kept no communication with and nothing
that's there can affect us so I like to
sort of not included in my
considerations so I think it will not
affect our our physics and for me there
the fact that the universe has a finite
horizon at a certain this is with a
finite amount of information is actually
quite essential to the ideas that I've
been using here
got any on the one more fish the blue
one is there ya are you see you still
yes hello yeah thank you for the talk my
question sort of hooks into his question
you said that the boundary of the
universal defines information with the
amount of information within it does
that mean that the Greece expansion of
the universe is directly related to the
amount of entropy in the universe yes so
the Hubble Hubble parameter which is the
one that determines the expansion rate
of the of the universe is directly
related to the size of the horizon and
therefore that connection has to be made
so for me the Hubble constant becomes a
fundamental constant of the theory very
much like Einsteins called the Einstein
constant so he did the Newton's constant
and so the yeah the density of the
information or the amount of information
is directly related to that constant but
does that mean that entropy is the only
factor in the increased the increase
increased increase in size of the
universe we are let me say just yes I
think this okay thank you
the gets friction out there yeah
so you mentioned something about ferret
hoped holographic principle yes and that
basically all information in the
universe is represented at the horizon
at the surface of the universe and since
then this has been shown mathematically
to be the case for an anti D sitter
universe but in your talk you also
mentioned that in your theory
information is also included within the
universe itself so how do these two
ideas actually compare compared to each
other so the holographic principle does
not state that the information is on the
surface it says that there should not be
more information than the area the
surface that could be on the surface so
it's a it's a upper bound of the amount
of information can be insight it's true
that in anti-de sitter space which is a
universe without dark energy it lives on
the boundary and one of the main points
i've made here is that the appearance of
the horizon and the finite temperature
has to do with the fact that we live in
a universe with the positive dark energy
and if you want to know more about the
rest of the argument I say you would we
have to read my paper because that's
explained very in the beginning you have
a great oh I'll do that maybe I will
throw it okay yeah thanks for the very
interesting very interesting talk I was
wondering you talked about entanglement
and about information and they say that
entangled particles can transfer
information faster than lights do you
have any theories on that well it's not
exactly true
I mean entanglement is a state of the
two particles and in order to transfer
information which you can do say through
quantum teleportation you still have to
transfer a signal that goes with the
speed of light so there is no fast
communication possible with entanglement
- one here yeah my question was also
kinda really related to this one I was
wondering what if you have this
entangled particle two particles just on
the edge of the horizon and one goes
into the black hole and the other one
stays out then into the universe but
yeah it's literally your question no no
it's not actually but well UF DS a thing
of particles and they are related but
one is a Eureka the other side of the
horizon so you have exchange of
information it's the kind of paradox but
how do you see this well they're
entangled which is not again exchange of
information
I mean entanglement is just a statement
that an outcome of a certain measurement
here is correlated with the outcome of
an other measurement it's not a form of
information that's being sent over I
call it sort of sometimes shared
information in the sense it's the same
information that's available to both but
you cannot use it to send information
okay it arrives in the frontier yeah
thank you for your lecture I have a
question if we go ahead with the theory
of Big Bang so during the beginning of
the universe is a hot plasma and it
started expanding and once it started
expanding it it gets cooled down and and
all the plasma ingredients in the plasma
start coming together so mom can I have
whites you can we have the other screen
so my question is good could you please
explain what what is the rasp our force
is responsible for the ingredients in
this plasma to come together is it
gravity because we I really have to been
doing just this here this is my
interpretation of what that story is
just look at this white
I'm not gonna answer it I mean for me
the Big Bang is story is not believable
and it has to do with information it has
to do with the fact that the statement
there is that everything emerged from
something it's a story of the universe
that we like because we have been
reasoning backwards and in doing so we
have done what we normally do and
already explained it to an answer we
have done what we humans do is namely
perhaps make things abstract ignore
information throw it away so we have a
very simple picture of the beginning of
the universe and most of the information
that's there is considered irrelevant if
you would put it all back in again the
picture would be very very different the
mass may be similar but the story is
very different and so I don't buy this I
think this is really just a story that's
being told over and over again in such a
way that people start believing it and I
think if you think about it logically
it's not a very logical story actually
nothing in other parts of physics works
like this where something can begin at
the moment without having existed before
it
I think it's very clear thank you
yet there in the middle yes perhaps I'm
missing this 30 sir but is it truly so
that you suggest that dark matter
doesn't really exist yes
do we then also think that the same
applies to dark energy somewhere out
there no clear statement now for me dark
energy plays a very important role it
made the difference between this
universe without the information and
with it and I used the dynamics of dark
energy to explain the phenomena that we
attribute to dark matter so for me the
dark energy is the real thing that makes
that thing happening so the information
I talked about is associated with debt
and that's what's filling the universe
and what we observe in what we call dark
matter we think of it as a particle and
it would be sort of something else than
dark energy and so the current theory
would make no connection between dark
energy and dark matter but I claim that
what we observe is actually due to dark
energy and not due to dark dark matter
but what I mean is like because I think
there's so many questions we very little
time so we can continue and then there
will be drinks afterwards to discuss
even further yeah so I think we do two
more questions one blue question and one
gray question yeah you're the lucky blue
question um yes you see dark energy is
composing the majority of the entropy of
the University um but um but but but but
then the other explanation has always
been that is given by the cosmological
constant which which I just understand
it's a geometric argument is a geometric
constant it's the same as saying that
all of the molecules in this room can be
summarized by giving it a temperature
the motion of all the molecules
it's a simplification of what's going on
which effectively works very well
because for our daily experience that
temperature is a thing we care about and
the cosmological constant summarizes
what is most important for that
description this is the way that it
appears in Einstein's theory but I think
it's an oversimplification of the actual
dynamics that is going on so there's a
lot of dynamics going on in this dark
energy that is not described by general
relativity so you're saying the
cosmological constant is itself an
emergent phenomena that's correct it's
it's just like temperature is emergent
in thermodynamics great things so
there's a final question in the back do
you have an alternative theory to the
Big Bang I think I answered that
question already that's something that
needs to be developed
I have I can tell you what my thoughts
are all about so I think that indeed the
universe did not start in a short moment
but the idea of emergence is much more
subtle it means that something cannot
appear without out of nothing it must
appear from something else
so space and time have to be appearing
from something that was already existent
now if you ask me what is the mass that
goes with it one of them mathematical
descriptions I'm thinking about a lot is
called chaos so in chaos what happens is
that you have things that are
exponentially growing namely it's like
the bat butterfly effect if I have two
things very close by they may end up in
very different parts but generally when
you look at this then they're also
things decaying and some certain things
grow other things become less important
you can throw away the thing that's less
important because you cannot observe it
but then you are only left with things
that grow and that's what the universe
description now looks like but if you
take the entire description you see that
everything actually is preserved nothing
really gets bigger as actually all of
the volume even all of the information
gets preserved so it's a much different
description but effectively you might
fight the equations in there that we're
now currently using to describe the Big
Bang
that the theory itself will be much more
complete in terms of computing track of
all of the information that's there and
but anyway I'm not gonna speculate too
much about what the mass exactly looks
like this is something that needs to be
worked out
thank you sure yeah it was great I think
we will hear still a lot from you in
from new theories and I think if I look
at this room there are many young
students that maybe look at you the way
you looked at here a television program
when you were young is there any message
you want to give to the students like
how they how they can be the next people
that make great theories or do great
physics well I think first of all you
must be doing what you find most
interesting with everything I think even
if you start doing research later for
your massive project or for any anything
when you do something that you really
like doing you are much more effective
and much more likely to be successful
and indeed ask yourself what what are
the questions you're interested in and
what is it what you want to do and if
you go for that I mean I I knew it when
I need to start it before I started
studying and I kept the focus on that so
if you have some idea but you really
like and and you want to go after you
should do it in focus
thank you very much for being here it's
it's been great
you

yeah welcome everyone in this great

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space-time::noun | Spocien Dictionary

space-time

noun

/speɪc_taɪm/

the four-dimensional coordinate system (3 dimensions of space and 1 of time) in which physical events are located

Type	Words
Synonyms	space-time continuum
Type of	coordinate system, frame of reference, reference frame, reference system

How to pronounce space-time in Dutch?

space-time::noun | Spocien Dictionary

abandonment

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