The Physics and Philosophy of Time - with Carlo Rovelli

it's shocking in my opinion is one of

the most shocking thing in its fact the

most astonishing conclusion of modern

physics which is we now are here what

now

means what is the meaning of now well I

know what is meaning of now for me huh

you know what is the meaning of now for

you is it the same now

thank you thank you for this very kind

of introduction the first thing I have

to do is to pull up this which I've

prepared before you came in let's see if

it yes sorry which I'm gonna use and

that would be my high high technological

equipment to talk about time that would

be my metaphor of time right time is a

time is a long line there is a present

there's a the past of our past more for

our past this is 10 minutes ago this is

yesterday it is last year down there is

Big Bang this is tomorrow and the future

we don't know so this is this is a

metaphor of time we're sort of here we

have one hour whatever with questions

and and so on so we're gonna cover that

and I'm gonna tell you that time is not

like that the message and so what I'm

gonna what I want to do is to give you a

sense of where I think we are about

understanding of this strange mysterious

things which is time it will be sort of

a journey for me time has been a an open

question from my early years and that'll

say adolescent from all the way through

my studying of physics and then into my

work as a physicist you know sort of as

obsession because quantum gravity

requires us to rethink what is time I've

been going around around around this

this question what is time

so in the book and in what I want to

tell you tonight is it's a bit of a

synthesis so that where we are what we

know what we think is true including the

parts that we don't yet know we are

confused we are confused about and I

will do it is a taking you to a sort of

journey

journey which is back and forth so I'll

start from this idea of time this long

line that passes we're here actually we

moved a little bit already with more

years and time passes and I'll show what

quite rapidly tell you what's wrong with

this idea why this is a wrong idea about

time and in which sense it is wrong and

this would be a step sort of down into

more and more general views of nature

where time has less and less property

and loses its pieces so to say all the

way to what I think is the current

understanding of the structure of time

which is that there is very little time

in nature and that would be the journey

the one-way journey and then there is a

journey back which is how from this

nature at the level of quantum gravity

which is sort of the bottom level of our

understanding of the physical world in

sense of general Eiling generality flows

how from there we get back to this time

to the time of our our experience so it

will be a long one one way and return

trip where I want you to lose all the

ideas of time to then sort of understand

back where where our Comment I come from

right so this is this is the time of our

experience first of all it's a long line

namely what would I mean about a long

line it's a it's a see what we mean it's

a sequence of moments instant now before

later which is ordered like the English

when they wait for the bus so maybe I'm

trying to Italian eyes you

but I don't want you to crowd it for

getting the next bus but all this

instant are for milonga along the line

they're there the one next to another

one in a one-dimensional thing this line

is it has a direction right the past is

completely different for the future this

is one of the most obvious thing and it

was trivial thing to say but let me say

it precisely because then I'm gonna say

it's not true the past is fix it it's

given we remember it we know it we have

traces of it we have books talks about

the past we have a department of in our

university that study the past is

history

we don't have many departments that make

a historical history about the future

there are traces in in in nature if you

look at the moon there are craters that

are formed by stones fell into me in the

past so the pasture is all the spaces

where memories in our mind the future

there's nothing like that there's no

memory no traces still has to come right

so that's part of this idea that we have

about time um time has a symmetric

property maybe we can talk about

duration of time

this chart I'm giving this presentation

for the last 45 minutes certain fix the

amount of time that we measure with

clocks and we know what it means this

interval being equal to this integral

being equal to this integral in clocks

measure that in clocks are devices that

are meant to tell us where we are along

this line what time is it where is where

am I is it already tomorrow it's not yet

in clocks are designed to work all

together that's the purpose of a clock

so if you take two o'clock some of them

apart wait a little bit you bring them

back together they still have the same

time if they had the same time if not

means one crock is broke one clock is

broken it's not going well

thank you thoughts um this is a

retirement a little bit past this is a

time of our experience now what's wrong

with this image first of all there's

nothing wrong obviously

as long as we carry on our daily life

it's a very good construction conceptual

idea about time that works very well in

our in our daily life but it does not

work it stopped working when we look a

little bit more far ahead and the more

we look far ahead the more this number

of properties that I described about

time go away so the main message somehow

the fool talk I'm giving is a time it's

not a single thing it's this

multi-layered concept that has all this

property that I told you is one

dimensional as a metric is oriented

there is the same for every body's

measured by clock and so on and so forth

this which in our intuition comes as a

package is time it's properly thought as

a combination of properties that we can

dismount one by one time and sometimes

this is is layered or is like a mekinese

likely engine of your scooter you can

take away one piece the carburetor you

can take away the piston you can take

away this you can take away that and

what remains is not the scooter what

remains is nothing at all and that's

going to happen we think when you take

away this take away that taker with that

what remains is nothing at all because

time is a combination of these

properties so let's see what properties

one by one the first one maybe I

mentioned three or four of these let's

say for to dismantle this idea of time

some of this you may know depending of

how much physics you know or

Shifa you've heard these stories already

some you probably haven't known some are

very solid knowledge some are things we

suspect them I would say the first three

a very solid knowledge but the

implications of taking all them together

are strong so first one clocks measure

time fine and clocks go all together at

the same spin speed oh that's wrong why

is wrong because it's a fact that if I

take two clocks and if I take two good

clocks and I move them apart remove one

or bring one higher and keep one lower

and I wait a little bit and I move them

together if these are good enough clocks

they will indicate a different time it's

a fact okay it was clearly understood by

a nice nine hundred years ago so in a

sense we've been knowing this for

hundred years but it's recent that we

actually have good rocks not these that

we can measure this and today with

atomic clocks with clocks that measure

easily one part time with an error one

in 10 to the 18 17 18 even 19 this is

very rapid advancing the technology of

clocks

so with these clocks you can take two

clocks at a different of altitude of 40

centimeters 50 centimeters and measure

that so the clock up here goes faster

than the clock down here there's more

time here there's more time for thinking

for for growing older for everything so

there is more time in your your head is

older than your feet your head as unless

you've spent all your time upside down

in which case is the other way around

okay why well why is it it's

it's a funny question yes one could say

why well because we know from general

relativity that the switch is a big rock

big mass slows down time so math slows

down next to it but why I think the

right question is why not

why is still this hard for us to digest

because we're used to time being the

same for everybody we used is to person

have the same age and they separate one

who goes to America the other goes to

China and they come back after a while

they still have the same age

that's our experience but that's not

right because they've aged it

differently depending on how they moved

the paintings have lived ups more up or

more down and and so on in our

experience

these differences are small and smaller

than our perception of time or the the

precision of our watches that we we

carry so we don't we don't we don't

notice that but if we lived a little bit

in in the future when I hope there will

be starships going around a fast speed

and coming down we will have to get

confront that so the reason for which we

think the time is the same for everybody

is because we used it we got used to

each by our approximation it's like you

know if we if you grew up in in the

Netherlands which is completely flat you

think that the earth is just all of the

same level and somebody says you know

there are some places of the earth with

us goes down who say no yeah it's called

mountains Wow right you have never seen

mountains then so you're surprised we

live in a region in which this

difference of time is small so we're not

used to this if we had a big massive

black hole not far from here will be

used to the fact that when you go to a

black hole you come back everybody else

as much has grown older than you good

which means already that this line is

just

wrong because the the time between here

and here two events is not fixed it

depends whether you were higher or

whether were lower for instance so it's

not there isn't a single time in the

universe already there are many times in

fact in ice ice and generativity they

don't have a single time we have one

time probably for every line good that's

point one now point to that follow quite

rapidly from that which in fact

something that Einstein realized even

before generative is special activity

but it has long take long for for

becoming absorbed because it is shocking

in my opinion is one of the most

shocking thing in fact the most

astonishing conclusion of modern physics

which is we now are here what now means

what is the meaning of now well I know

what is meaning of now for me you know

what is the meaning of now for you is it

the same now obviously yes because I

look at you you look at me and I say now

you say yes now I hear yes now so we're

in the same now right then wait a little

bit look at we are new now so a little

bit more moved here but we are together

always together the same now the think

of a moment when we look her out if I

look at you do I see you now well not

really because time lights take time to

come from you to me right so I see you

sort of a little bit in the past now

time takes a few nanoseconds to come

from you to me so I see you as you were

a few nanoseconds ago nanoseconds are

irrelevant but if you were on Jupiter I

would see you two hours ago and if you

were on a star I will see you four years

ago

close the star and if you were on

different galaxies and drum and I would

see millions of years ago so I couldn't

say now is

you see I see you and if you look at me

in the moment I see you you you are

gonna see me in the past in the future

for me so between the UIC and the you

that see me in the moment I see you

there's an interval between the two

which is a few nanosecond here

but few hours in Jupiter and millions of

year if you were in a different galaxy

so if the people in a different galaxy

want to know what we are doing now they

don't know because they're looking

somehow there is all this time for so

one say well alright okay this is

because it's hard to check but we can

devise things to say what it means to be

at the same time for instance I could

say well I look at you but I know you at

a certain distance you're in Jupiter but

I know it takes half an hour I'll take

four hours light to come here so four

hours in the future for when I look at

you that's now okay except that you be

maybe moving fast and four hours in the

future could be in my own future

maybe 10 years in my future so how come

the now be 10 years the future does make

any sense so the more you play this game

the more you realize that it's a

question which is ill posed there is no

meaning of now outside the approximation

in which we can disregard the time light

goes back and forth so what we mean by

now is we both look at one another and

we are in the same temporalities within

the resolution of time that we have

which means that the notion of now makes

sense on a radius on our honor on a

bubble around us which has a length size

L which is given by the speed of light

time the minimum resolution of time that

we can resolve the delta T we can

resolve that's the meaning of now there

is no meaning of now outside

this bubble with our brain without using

sophisticated clock to resolve probably

what a tenth of a second if you're a

musician you will be better than that a

tenth of a second light is much bigger

than the earth it's a big bubble around

the earth so on the earth we are all the

same now but it's just this Proxima B

which is a closest star has its own now

there's no sense of putting them

together you can set signal so one to

the other signal back but in between

there is no way of saying there's no

meaning of now and in fact people work

in general activities they're additions

work in general activity study solution

of Einstein equations they know very

well that this is four-dimensional

solution there is no preferred now no

objective now that you can pick up us

from from physics of from anything why I

said why this astonishing because what

is it real what does it mean to be real

well we are told that what is real is

real now right it's a Roman Empire real

no it was real in the past not now ok

but this now is only local it's

something happening on a distant

galaxies real well it may be in the

future maybe in the past but if

everything is real in between it's

confusing because there are things which

are the past on the future one another

what did this mean to be real after we

have understood that the world works

like that namely that there is not now

in the universe there are philosophers

who are discussing there that's why I

talked the philosopher who are

discussing that and and and you know

pulling each other here is and fighting

the the very meaning of being real of

reality in the sense of what is real now

has to be rethought after what we've

understood about about physics so the

idea of one insert of time it's

completely destroyed in our

little bubble we can talk about instance

of time that we share provided that we

don't go too fast we don't we don't not

precise but globally there is this

series of events in the universe with

some temporal relation between a couple

of them but no common now at all and no

order no order in the mathematical sense

two three and this is a little bit more

complicated and less well understood the

first well understood the first part

less understood the second part the past

is different from the future right where

there is a local past local future it's

the past Atif of the future so let's

forget that other galaxies select loop

let's look around us and yesterday is

completely different story than tomorrow

yes it is fix that we know it tomorrow

it's open we don't know it good so I'm a

physicist I want to know where does this

distinction come from in the laws of

physics and as you probably know the

laws of mechanics don't have this

distinction the laws of electrolyte

Yeti's don't have this distinction

Standard Model of particle physics does

not have this distinction general

relativity does not have this

distinction right so all the basic

equations of physics quantum field

theory does not have this distinction

all the fundamental equation of physics

luckly distinction between past and

future but for us the past is completely

different for the future we have books

written in the past we don't have book

through it in the future so where does

this thing shall come from well there is

a story about that which is there's one

finds that sees clearly the distinction

between the past and future with

thermodynamics and in thermodynamics is

one law which is a second

thermodynamics the the second principle

of thermodynamics that says that entropy

always grossed over the future so that

clearly makes a distinction between the

past and the future fantastic so we've

found the basic the key fundamental

grammar of the world the elemental

machine that distinguish the past or the

future that law was written by trousers

19th century but shortly later sometime

later Boltzmann and his friends marks

will also but Boston was I think the

person was greatest clarity understand

that this law is statistical namely

Boltzmann understand that is entropy

this quantity that you can compute

category and chemistry always compute

the entropy in in a reaction energy heat

you do this calculation you get the

entropy before and to be look after and

it always goes up Boltzmann understand

that the entropy is just not a

fundamental quantity but a measure of

how how mechanical things are disordered

right you know that

entropies disorder that's a great sort

of understanding that we we got

footballs but what mean disorder you

take you take a box you have some green

balls some red balls you put all the

green on one side the red on the other

side this is ordered you mix everything

this is disordered and if an entropy

counts exactly that how much order how

much disorder if they're separated this

low entropy do your little calculation

or entropy for mixes high entropy which

makes a lot of sense because when you

shake things I get disordered so entropy

goes up good now you look at these balls

green and red and your friend is

colorblind so he doesn't see any order

because his collar bright it doesn't see

any order so for him there's no order

for you to his order but actually is

worth of that your friend

a very keen eye that distinguished some

wolf you were a little small and some

little bit bit larger much better eyes

at yours you don't see this difference

so for him order means all the little

balls on one side all the big balls on

the other side so for him the entropy is

a completely different story so what we

mean by the order of the world see I

think you see clearly that order is in

the eye of the person who looks it's not

in the things themselves order counts

once instead of recognizing the balls

one by one if you if you number all the

balls and all of you give names to all

the balls whatever the way you put them

they are ordered in that particular way

[Music]

is only by distinguishing two big

bunches of balls that you can talk about

order or disorder and in thermodynamics

when Boltzmann understands a statistical

and depending on thermodynamics he

thinks he understand is that the notion

of entropy depend on the macroscopic

variables that you use to describe the

system on the coarse graining of the

system which is a simplification of

description the system which disappears

if you look at the micro physics of the

system all right so what does it mean it

means that this growing of entropy it's

tied to the approximation we make in

describing a system it's not fake is not

illusionary

but it depends on the way we've we've

described the system or the macroscopic

wave we have described the system which

in turns depend of how interact with a

system so it's not a mental thing is not

idealistic thing so the subjective

things the really concrete things depend

on the way you interact with a system

then we interact with the system is your

interaction with some variables of the

system which are few out of the many and

these few determine a coarse graining of

the microscopic variables and define a

name to be and then to be gross

oh this is fine so in the future the MPT

grows in the past the entropy with

respect to our coarse graining was slow

why was it universe all do it in the

past who order it I mean few if you go

to your little children little child

bedroom and they even is a complete mess

and the morning is an order

you know why is in order because

somebody put it in order but why the

Union who prepared the universe in order

and the universe in order in the right

way that looks in order for us mystery

yeah what does it have to do with time

everything because the distinction

between the past and the future is only

that is this strange order in the past

and I want you to reflect about that

because I'm saying something very very

strong this has been recognized by some

people I came back in the philosophy of

science Russell have clear ideas about

that but few it hasn't permeated I think

the the the global thinking about the

order of time everything in our

experience which is ordered in time is

because of entropy there is nothing else

in the world that distinguish the past

in the future except this entropy

concretely

any phenomenon that you can imagine

where you distinguish future for past

this an entropy if you if I throw this

it stops right if you film it and if you

look at back back backwards

this is starts by itself so you said no

no no no that's wrong so this is a

irreversible phenomenon okay there is

entropy

namely this heat what is going on is

that is friction and the mechanical

energy of the clock goes into thermal

energy off the table that go is a little

bit heated up

so all the molecules start of the table

start agitating because of the friction

and the order the motion of the clock is

transforming a disordered motion of the

of the molecules right every time there

is this thing shoved in the past the

future is because it's heat this entropy

this temperature

involved if there's no heat no

temperature if this rolls

this is move without heat it will go

forever and if you feel and and and

project it backward it goes forever in

the opposite direction

you wouldn't distinctly the future or

the past any mechanical thing you can

think about pendulum without friction

you take a movie you project the

backward with a pendulum the solar

system the earth of the moon goes around

suppose you film it you project it

backward who can say which isn't the

right one it's exactly the same motion

to distinguish in the past in the future

you need entropy disorder which means

that the reason we have traces of the

past has not in the future is nothing

else that entropy okay if we have a

texture say something it had to be this

has had to be some enter production some

heat some disorder at some point if a

monk in the Middle Ages in a monastery

wrote down something and now we know

something about the middle age because

we have this text in a world without

friction the ink would have not stayed

on the paper would have chopped away so

you need friction is a the ink glues to

the paper because it produces a little

bit of heat that this dissipate and so

it's some disorder which can happen

because it was a higher order in the

past so it is high order in the past

that determines the existence of traces

and we think in terms of cause and

effect

cause coming first and effect becoming

after only because of the second

dynamics because of entropy otherwise

there could be no dis symmetry

no physics says that the physical if

this is connected to that this is

connected to that both way we cannot say

this causes this more than this causes

that because the symmetric Russell used

to say that the notion of course would

disappear is wrong it doesn't belong to

physics it would be recognizes as

something what is it

totally useless and mistakenly

mistakenly considered non damaging like

the British monarchy and and and sooner

or later we'll get rid of it he was

wrong but we'll come back why why he was

wrong the point is that the entire

distinction between past and future is a

microscopical effect due to the fact

that under our perspective the past look

more ordered so not only the instant of

time is not aligned because every line

in the universe has its own it's on its

own temper allottee not only makes no

sense to take one to talk about the now

of the universe but the distinction with

one direction of time they are the

direction of time is some strange

microscopical effect which you don't see

in the micro physics 3 oh boy time is

passing fast us

I should speed up I am gonna speed up

because the fourth reason for which the

our community of time is completely

wrong is less solid than the first three

first two is science of unison very well

the fourth reason is the science that I

do so it's less solid why because I'm

still doing it right it's not yet in the

textbook i and all my friends we're

working on and the point is that there

is a connection which I just mentioned

before between time and gravity gravity

the mass effect

the speed of time but we know that

gravity that the understanding way of

gravity may disregard quantum mechanics

so this is the proper quantum gravity

this job of my life so I'm paid for to

try to write the equation for quantum

gravity there are a set of equation that

we have written down for describing the

quantum properties of gravity and these

equations tell us something about this

what the clock measure and tell us I

would say three things one is that a

anything that works like a clock cannot

measure time local time continuously

because there's a minimal amount of time

so there is something granular in the

passage of time I understand that in the

UK there is a current debate on children

not being able to read analogous clocks

so they only read the digital clocks so

they come out with the wrong idea that

time is discrete that is digital right

which is the right thing so very good I

don't see why kids should be able to

read digital clock I wasn't very good in

reading digital clock when I was a kid

because I didn't use clock so Chinese

digital as a very short scale of course

not seconds of fraction of a second of

the Planck scale 10 to the minus 44

seconds very very small time intervals

but that's a minimal timing there's no

smaller time interval than that not only

that but the clocks itself because a

quantum object everything's a quantum

object can be in super positions of

different position of the handle a

different reading so you cannot say that

between this event and this event is a

certain amount of time there because as

always in quantum mechanics there could

be a probability distribution of time

passing from one and the other so you

see that everything you use to think

about time disappears when you go to the

widest possible

situation which is quantum gravity which

you keep into account everything we know

about the world world today in fact in

the equations of look onto gravity the

theory which I'm working brings together

quantum mechanics general activity in

the equations of that theory there is no

time variable at all why because you

don't need a time variable you have a

lot of variables you have a lot of

clocks you have a lot of things that

change at the basic level time is just

any way of counting the change of

something which by the way is the

definition of time that Aristotle gave

25 whatever centuries ago time is a

number of changing you look at something

changing day night day night day night

you count and this is time time is a

counting of change then Newton came out

with this idea

you completely knew that time is not

just a changing of something but it's

some uniformly flowing something that

flows irrespectively of whether is

matter changing or not is completely

Newtonian idea is a new idea it is in

your mind because you studied it at

school because it's a permeated our

society but it's not the old way of

thinking about that the old way of

thinking about time is that you see sink

changing you number them she's fine

but Newton comes up we said well there

is that way of seeing of times it's not

other way of thinking of time my

newtonian way which is the time just

passes even if nothing changes then I

still recognizes that this Newtonian

time in this Newtonian space which also

you to introduce city of empty space

there's nothing else about space um are

actually the gravitation field it's

nothing else the gravitational field so

I think in a sense says oh yeah you're

right Newton that there is something

else beside the counting of things

there's this absolute time maps of space

but you're wrong in not seeing that

these are dynamical object is just

electromagnetic wave it's just a little

magnetic field this is a gravitational

field so it's a sort of

something that fills up everything which

is the Einstein four-dimensional a

curved space-time and once you realize

that this ice and four dimensional

curved space-time which is a

gravitational field as quantum

properties it can be in superposition is

granular it has all the funny thing

there does all the funny things up when

two things do the Newtonian time is a

completely exploded it depends on the

interaction is granulars

different point of point there is two T

Leontine the basic idea that you can

count event still there so in quantum

gravity of events not order it in line

that the British but all confused like

the Italians connected to one another

you can follow this one this one this

one and you can see okay doing this blah

blah blah number of things happened so

this moved a certain number of clicks

and so you can have a local notion of

sequence of event which is a minimal

notion of time and that's the only thing

that remains locally probabilistic

discrete without a prefer a time

variable anything at work as a variable

and that's the no time the minimum time

of quantum gravity I promised you a

journey back so I have less time

remaining because I was supposed to

finish here and already here to take you

back so I hope I convinced you well I

don't hope I convince you I hope I gave

you a sense of the very very weak

temporal notion needed to do fundamental

physics I've written a paper whose title

is forget time so write the fundamental

equation of quantum gravity and if you

don't see there which one's the time

variable don't worry you don't need a

time variable because the time variable

is something microscopic not something

down there down there if many variables

change one or respect to another how do

we go back from there from that

basic reality we have to find the

conditions under which we live which

allow us to talk about this long line

oriented and common which is time and

this is a number of steps there are many

steps different levels different layers

each one is interesting by itself but

they're separated time doesn't come up

off in one step comes up at various

levels first of all the granularity of

time is so small we don't have such

precision so we don't see it

this flow we can see it continues the

quantum mechanical superposition aspect

of time we are big and heavy and much

work at scale much larger than the

Planck constant which is what determines

the quantum mechanical effect so we

don't see it so we actually see a

gravitational field as a continuous

things like I stand described but we

live in a region in which gravity is

very very weak compared to black hole

though is really strong and is very very

weak essentially this nice thing curved

space time is flat and this is flat

Einstein space time are assembled very

much Newtonian space in Newtonian time

not exactly because link Oskie

space-time but very much but we don't

move fast to respect one respect to one

another so we can disregard the time

back and forth of the light and we are

so so we can assume that light instead

of going a finite speed goes at infinite

speed because now experience life is

sent essentially infinite velocity don't

resolve the light travel at a time

travel of light so if time is a at

infinite speed then we have these

surfaces of simultaneity we can think

that we're in this in our bubble and so

we can talk about one single time right

so now we have a one-dimensional line

which is still not oriented past and

future so what is it oriented it past if

you

well let's go slowly first of all

remember it's entropy entropy depend on

the way we look at the world or the way

we interact with respect to the world so

I think and take this as an hypothesis

not as something demonstrated some of my

colleagues disagree that what makes

entropy low down there in the past

saying the early universe entropy was

very very low he's not the fact that the

universe was arranged in a very ordered

way the universe was arranged whatever

it was a you arranged is the fact that

we look at the universe we interact with

the rest in a way which is very

particular because we are particular we

meaning we as a physical system

interacting with the race though such

that under this perspective the past was

special imagine you take a cart you mix

them you look at them and you remember

the order okay that order disappears

when you mix again so you see a

increasing of disorder but that order

was special because you decided to a

special you looked at them and learned

it so in some sense we are special

subset of the universe that interact

with the rest of the universe in such a

way then the past looks ordered to us

what is special is not the universe is a

subset of the universe to which we

belong this is called area the Pacific

title origin of entropy and I think it

could be an ingredient for understanding

why the past even for the future there's

nothing special in the early universe is

special the microscopy the coarse

graining that we do are we done not yet

not yet and there is a last step and to

me this has been the greatest surprise

and here I'm stepping a little bit out

of my own comfortable zone but it's what

I've been learning and learning and

um there is something about time which

is still missing

and there are some philosopher even some

physicists who says we have got the

entire story wrong because time flows

train passes time sort of passes at a

certain speed and we don't see that in

all this physical picture so maybe there

is some fundamental fundamental

fundamental law of time that says after

all there is this passing of time I

think they're right they're wrong and

and and many other colleagues of mine

including many Philosopher's

increasingly getting convinced that what

we refer to when we refer to this

flowing of time this passing of time

this clear feeling that we have about

the flowing of time is not in the

quantum gravity is not in generative it

is not in quantum mechanics is not in

thermodynamics is in the specific way

our brain works and there is an enormous

amount of working today in the

neurosciences in the function our brain

with a title of a book by a

neuroscientist called dilben Amano

a recent book in America if the title is

your brain is a time machine what does

it mean the way the brain works is to

exploit this entropy gradient and the

fact there traces of the past to build

memories and in terms of this compute

the future and anticipate the future

that's basic working of the plane

according to one of the importance of

how the brain works so the brain is the

time machine brings us continuously sort

of grasping to some events in this

confused set of events around ask we are

connected by traces to some event tour

the past we are connected by

anticipation on the other direction so

in our mind there is this opening space

okay you think that this is a metaphor

of what this is metaphor our memories of

some of the past and in fact that's why

is much more confused over the future

because we don't have

of the future when we think about time

very often we're not thinking about the

physical part of the physical future but

we are considering the memories we have

about physical person and and the anta

patient we have about the future um

philosopher has been saying that for a

very long time who sir has been saying

that it goes back to st. Augustine

famous pages about the nature of time in

his book the confessions he says when I

listen to music I get a meaning from a

musical phrase but I never listen to the

phrase I listen to one note at a time

right if I listen to one note how do I

know about the previous notes okay get

the meaning well of course I know

because I remember them but if I

remember them and who sir is very clear

in that the meaning comes from the notes

beings playing now and the memories of

the previous one so it's all in the

present so to say and it can be only the

present together because as memory but

it's more than that

because since the brain is designed by

evolution to use memory to anticipate

for a purpose because it it designed to

try to get somewhere that that's how

living evolution design our our our

behavior then all this is strongly

emotionally charged the passage of time

is not for us a rational thing to

contemplate it's something we live in -

we are the past this passage of time

where this constant computing of time

you can think about reality without

space we can think about reality without

things you can say it's very hard to

think yourself in a reality without time

you wouldn't know how to start thinking

but the confusion is is this because

rarity by itself cannot be thought

without time no is because our thinking

cannot be talked about time we cannot

think

we are a time machine not the universe

use a time machine you use just a bunch

of thing of events vertically connected

to one another which in some

approximation are nicely ordered but

what we think when we think about time

is the personal of the memory and in the

anticipation give us the sense that we

are in this space right all of us what

is the real time real time is now ten

minutes ago my life but then I've been

to school so I know about all the kings

of England

so this long line right the line of the

kings of England in Queens and and so I

have some extended memory which is a

cultural memory I've studied physics and

cosmology so I have this memory longer

it's all today it's all my knowledge

days all here in the book I talk about

post post as the reason has written this

fantastic novel in search of lost time

it's all about time he says that

explicitly section of the meaning of

time and the novel is full of stories

character things but then novel is

presented not as what is happening in

the world or what has happened in the

world but as the memory of the main

character whose name is probably Marcel

so all the 3,000 pages of Proust novel

are about what's in this you know five

inches between the years of Marcel it's

all here and that's the greatest

intuition of truth to understand what is

time for us we have to look at the

specific of our brain functioning more

than the temporal structural universe

itself of course these religions were

not saying that temple structures unit

still is irrelevant but I'm saying that

by looking only at the temporal

structure of the units you always get

the feeling that there's something

missing with respect to the time of our

experience and so you do metaphysical

speculation about the primary key of

time to completely wrong because of

course there's something

because doesn't pertain to the

fundamental strike for us it pertain to

the way our brain machine works and last

point it's truly emotionally colored

time is not emotionally neutral to us

precisely because we are our brain is a

machine designed to tell the story about

the past and do something in the future

we are full of motivation hunger if

thirst

we have ambition with curiosity with

love with hate that's what we are

before being rational beings and this

drive is the drive of the brain that you

know control our hostesses and and and

and and struggle to make us survive and

do better because evolution wants us to

be like that it's already entering time

it's all in time so time is emotionally

charged for us time is what brings us

things we want is the opening of the

future okay in time is what is motional

charge for us because it makes us lose

thing constantly all the time in in in

in Buddhism there is the speed

psychological side I think the main

truth of Buddhism IRS's life is

sufferance but the second is that the

life is sufferance because we have

difficulty of dealing with impermanence

with time so time is a source of our

suffering we suffer because we lose

thing or because we have lost things or

because we shall we think we will lose

things so it's we're gonna die so this

is a quintessential

source of anxiety for for human so x is

strongly colored emotionally and why I'm

saying this because I think if we think

that this emotional side of time is a

sort of fog that does not allow us to

see the real nature of time we are

confusing yourself because this

emotional aspect of time is precisely

what is deeply time for us

time for us is this emotional connection

to the event of the world that go away

that pass that flow that we lose and

this is a looot of our strong sense of

passing time and feeling feeling time is

ingrained working of our of our brain

this is vaguely connected to this event

it works because it's entropy of course

because it our scale we can orient Orion

things like like like this but you see

understanding time means bringing out

the pieces of the of the of this layer

the complex object time is not a single

thing is all my grass is not a single

thing is all these layers that come from

approximation from this regarding aspect

of nature from thermodynamics from our

particular relation to the world n from

our function if our brain including this

emotional level out there the more we go

general in the picture of the universe

the more time loses species there is a

very weak form of temporality and in

closest to us I think the strong

emotional connection with time the

motion of time is what time is for us

you