The Story of Black Hole | Prof Pankaj Joshi | TEDxICTMumbai

alright I’ll tell you about the stars

alright I’ll tell you about the stars and black holes and the universe as a

and black holes and the universe as a

and black holes and the universe as a whole

whole

whole this is the story of black hole it’s a

this is the story of black hole it’s a

this is the story of black hole it’s a fascinating tale of Education evolution

fascinating tale of Education evolution

fascinating tale of Education evolution of our knowledge on universe how the

of our knowledge on universe how the

of our knowledge on universe how the things change how things evolve how we

things change how things evolve how we

things change how things evolve how we you know as we go on observing the

you know as we go on observing the

you know as we go on observing the universe which way we keep revising our

universe which way we keep revising our

universe which way we keep revising our ideas on the cosmos that’s the whole

ideas on the cosmos that’s the whole

ideas on the cosmos that’s the whole game we are all here very busy doing our

game we are all here very busy doing our

game we are all here very busy doing our day to day course every studies life

day to day course every studies life

day to day course every studies life family so on and so forth so many things

family so on and so forth so many things

family so on and so forth so many things we have to attend every day but then we

we have to attend every day but then we

we have to attend every day but then we have to realize we are part of a vast

have to realize we are part of a vast

have to realize we are part of a vast universe we are not you know alone we

universe we are not you know alone we

universe we are not you know alone we are part of an entirety and then as you

are part of an entirety and then as you

are part of an entirety and then as you look out there in the cosmos

look out there in the cosmos

look out there in the cosmos you see what we call galaxies this are

you see what we call galaxies this are

you see what we call galaxies this are you see the galaxies that you see from

you see the galaxies that you see from

you see the galaxies that you see from the Hubble telescope there are billions

the Hubble telescope there are billions

the Hubble telescope there are billions of galaxies that you see in the universe

of galaxies that you see in the universe

of galaxies that you see in the universe and each of that like this one consists

and each of that like this one consists

and each of that like this one consists of some 400 to 500 billions of stars

of some 400 to 500 billions of stars

of some 400 to 500 billions of stars billions of stars and then our own Sun

billions of stars and then our own Sun

billions of stars and then our own Sun and that Sun is just a one tiny dot even

and that Sun is just a one tiny dot even

and that Sun is just a one tiny dot even if this one tiny dot contains hundreds

if this one tiny dot contains hundreds

if this one tiny dot contains hundreds of stars so big is one single galaxy

of stars so big is one single galaxy

of stars so big is one single galaxy this Sun is as small as this one but

this Sun is as small as this one but

this Sun is as small as this one but there are stars this big in the universe

there are stars this big in the universe

there are stars this big in the universe thousands

thousands

thousands 10 times the Sun 20 times the Sun or

10 times the Sun 20 times the Sun or

10 times the Sun 20 times the Sun or even you know 100 times the mass of the

even you know 100 times the mass of the

even you know 100 times the mass of the Sun big big stars are there in the

Sun big big stars are there in the

Sun big big stars are there in the universe what happens to them when they

universe what happens to them when they

universe what happens to them when they exist they’re internal nuclear fuel as

exist they’re internal nuclear fuel as

exist they’re internal nuclear fuel as you know probably the hydrogen atoms

you know probably the hydrogen atoms

you know probably the hydrogen atoms fused together in the Sun to produce

fused together in the Sun to produce

fused together in the Sun to produce energy and then at some day the hydrogen

energy and then at some day the hydrogen

energy and then at some day the hydrogen is going to get or even within the Sun

is going to get or even within the Sun

is going to get or even within the Sun the Sun has lived some 5 billion years

the Sun has lived some 5 billion years

the Sun has lived some 5 billion years in the past but never mind it is going

in the past but never mind it is going

in the past but never mind it is going to live another 5 billion years so you

to live another 5 billion years so you

to live another 5 billion years so you can have many more TED Talks here and

can have many more TED Talks here and

can have many more TED Talks here and you know many more degrees and your

you know many more degrees and your

you know many more degrees and your usually your carriers to make your

usually your carriers to make your

usually your carriers to make your financial planning to do your families

financial planning to do your families

financial planning to do your families to make your children the important

to make your children the important

to make your children the important point is the life cycle of Sun is very

point is the life cycle of Sun is very

point is the life cycle of Sun is very different from life cycles of massive

different from life cycles of massive

different from life cycles of massive stars when the stars are more massive

stars when the stars are more massive

stars when the stars are more massive say 10 or 20 times the mass of the Sun

say 10 or 20 times the mass of the Sun

say 10 or 20 times the mass of the Sun then they burn much much faster their

then they burn much much faster their

then they burn much much faster their life cycle is their internal burning is

life cycle is their internal burning is

life cycle is their internal burning is much faster their fuel will get over

much faster their fuel will get over

much faster their fuel will get over very soon and then what is the final

very soon and then what is the final

very soon and then what is the final fate of such massive stars that is the

fate of such massive stars that is the

fate of such massive stars that is the you know beginning of the story of the

you know beginning of the story of the

you know beginning of the story of the black hole which is I think everyone has

black hole which is I think everyone has

black hole which is I think everyone has probably read somewhere or the other in

probably read somewhere or the other in

probably read somewhere or the other in the newspapers so

the newspapers so

the newspapers so to find out that particular you know

to find out that particular you know

to find out that particular you know answer you need the theory of relativity

answer you need the theory of relativity

answer you need the theory of relativity of Einstein because what happens is

of Einstein because what happens is

of Einstein because what happens is really this star is governing at the you

really this star is governing at the you

really this star is governing at the you know is governed by the internal nuclear

know is governed by the internal nuclear

know is governed by the internal nuclear fuel as I said cycle and then what

fuel as I said cycle and then what

fuel as I said cycle and then what happens then is the gravity takes over

happens then is the gravity takes over

happens then is the gravity takes over it is the entire game of gravity that is

it is the entire game of gravity that is

it is the entire game of gravity that is what counts in 1939 Oppenheim ER and

what counts in 1939 Oppenheim ER and

what counts in 1939 Oppenheim ER and Schneider the famous you know physicist

Schneider the famous you know physicist

Schneider the famous you know physicist Robert Oppenheimer and his student they

Robert Oppenheimer and his student they

Robert Oppenheimer and his student they worked out the using Einstein’s

worked out the using Einstein’s

worked out the using Einstein’s equations what will happen to you know a

equations what will happen to you know a

equations what will happen to you know a massive star and they found out that the

massive star and they found out that the

massive star and they found out that the entire star which is thousands of

entire star which is thousands of

entire star which is thousands of kilometers in radius it will collapse to

kilometers in radius it will collapse to

kilometers in radius it will collapse to one single dot like the one in IE

one single dot like the one in IE

one single dot like the one in IE english IE you put on the top that dot

english IE you put on the top that dot

english IE you put on the top that dot smaller than that size and within a

smaller than that size and within a

smaller than that size and within a matter of few minutes tens of seconds

matter of few minutes tens of seconds

matter of few minutes tens of seconds the star which lived millions of years

the star which lived millions of years

the star which lived millions of years will you know collapse like that and

will you know collapse like that and

will you know collapse like that and that kind of a dot is really the

that kind of a dot is really the

that kind of a dot is really the spacetime singularity in the same year

spacetime singularity in the same year

spacetime singularity in the same year 1939 as Oppenheim arranged neither did

1939 as Oppenheim arranged neither did

1939 as Oppenheim arranged neither did their work immediately

their work immediately

their work immediately Einstein was very displeased and unhappy

Einstein was very displeased and unhappy

Einstein was very displeased and unhappy with their work he straight away sake

with their work he straight away sake

with their work he straight away sake know nothing doing a star cannot do it

know nothing doing a star cannot do it

know nothing doing a star cannot do it how can a star columns like this and

how can a star columns like this and

how can a star columns like this and become a point like that and then

become a point like that and then

become a point like that and then everyone was quiet

everyone was quiet

everyone was quiet Einstein has spoken you see so there

Einstein has spoken you see so there

Einstein has spoken you see so there were the total silence in the field but

were the total silence in the field but

were the total silence in the field but only in 1960s what happened was that

only in 1960s what happened was that

only in 1960s what happened was that amazing you know phenomena were

amazing you know phenomena were

amazing you know phenomena were discovered in the universe

discovered in the universe

discovered in the universe the quasars the radio galaxies and so

the quasars the radio galaxies and so

the quasars the radio galaxies and so much energy was produced over there that

much energy was produced over there that

much energy was produced over there that no usual known laws of physics would

no usual known laws of physics would

no usual known laws of physics would explain it

explain it

explain it and then people thought ha there was

and then people thought ha there was

and then people thought ha there was this Oppenheim where there was the

this Oppenheim where there was the

this Oppenheim where there was the Snyder act there was this concept of

Snyder act there was this concept of

Snyder act there was this concept of singularity concept of singularity

singularity concept of singularity

singularity concept of singularity hidden within the horizon of gravity and

hidden within the horizon of gravity and

hidden within the horizon of gravity and then big development started in nineteen

then big development started in nineteen

then big development started in nineteen sixties and seventies on black holes

sixties and seventies on black holes

sixties and seventies on black holes stiffen Hawking Roger Penrose John

stiffen Hawking Roger Penrose John

stiffen Hawking Roger Penrose John Miller Kip Thorne big big names you see

Miller Kip Thorne big big names you see

Miller Kip Thorne big big names you see and the huge development took place in

and the huge development took place in

and the huge development took place in the game so this is you know a kind of

the game so this is you know a kind of

the game so this is you know a kind of artist conception of black hole you

artist conception of black hole you

artist conception of black hole you can’t just see it like a star out there

can’t just see it like a star out there

can’t just see it like a star out there because by definition the black hole

because by definition the black hole

because by definition the black hole doesn’t allow you know any light to

doesn’t allow you know any light to

doesn’t allow you know any light to escape so it is known only through its a

escape so it is known only through its a

escape so it is known only through its a you know effect on its environment but

you know effect on its environment but

you know effect on its environment but then physicists applied in a very big

then physicists applied in a very big

then physicists applied in a very big way the hole of the black hole theory

way the hole of the black hole theory

way the hole of the black hole theory but there was one very important catch

but there was one very important catch

but there was one very important catch in the entire game and the catch was

in the entire game and the catch was

in the entire game and the catch was that people remembered you know the

that people remembered you know the

that people remembered you know the Oppenheimer Schneider work and people

Oppenheimer Schneider work and people

Oppenheimer Schneider work and people you know brought everything in but they

you know brought everything in but they

you know brought everything in but they had to you know show in general that

had to you know show in general that

had to you know show in general that every star will become only a black hole

every star will become only a black hole

every star will become only a black hole every massive star when it died it will

every massive star when it died it will

every massive star when it died it will become a black hole only this had to be

become a black hole only this had to be

become a black hole only this had to be proved because the open how much neither

proved because the open how much neither

proved because the open how much neither model was very simple so the scientists

model was very simple so the scientists

model was very simple so the scientists had not proved really that every massive

had not proved really that every massive

had not proved really that every massive star will you know go to a black hole

star will you know go to a black hole

star will you know go to a black hole only in the past many decades what has

only in the past many decades what has

only in the past many decades what has happened is that many many models have

happened is that many many models have

happened is that many many models have been worked out including you know the

been worked out including you know the

been worked out including you know the Indian groups also and what turned out

Indian groups also and what turned out

Indian groups also and what turned out is that the singularity I was talking

is that the singularity I was talking

is that the singularity I was talking about this star collapsed is collapsing

about this star collapsed is collapsing

about this star collapsed is collapsing to a singularity you know very very

to a singularity you know very very

to a singularity you know very very dense region sometimes it can be hidden

dense region sometimes it can be hidden

dense region sometimes it can be hidden within a black hole but at other times

within a black hole but at other times

within a black hole but at other times it can be visible also so then the

it can be visible also so then the

it can be visible also so then the hypothesis was given by Penrose fifty

hypothesis was given by Penrose fifty

hypothesis was given by Penrose fifty years ago exactly about 50 years ago

years ago exactly about 50 years ago

years ago exactly about 50 years ago that singularities must be hidden so he

that singularities must be hidden so he

that singularities must be hidden so he gave a more dramatic word no naked

gave a more dramatic word no naked

gave a more dramatic word no naked singularities and we must have a cosmic

singularities and we must have a cosmic

singularities and we must have a cosmic sensor hiding all singularities

sensor hiding all singularities

sensor hiding all singularities singularities are not so bad actually

singularities are not so bad actually

singularities are not so bad actually you don’t have to hide them but anyway

you don’t have to hide them but anyway

you don’t have to hide them but anyway in order to develop the black hole

in order to develop the black hole

in order to develop the black hole physics somehow scientists assumed this

physics somehow scientists assumed this

physics somehow scientists assumed this and the conclusion was both black holes

and the conclusion was both black holes

and the conclusion was both black holes invisible naked singularities develop as

invisible naked singularities develop as

invisible naked singularities develop as collapse final states lots of groups

collapse final states lots of groups

collapse final states lots of groups worked out all this results over past

worked out all this results over past

worked out all this results over past you know at two three decades including

you know at two three decades including

you know at two three decades including our one a group also the important point

our one a group also the important point

our one a group also the important point here is that

here is that

here is that to tell you in pictures this earlier

to tell you in pictures this earlier

to tell you in pictures this earlier scientists thought that sun-like stars

scientists thought that sun-like stars

scientists thought that sun-like stars will become white dwarfs but more

will become white dwarfs but more

will become white dwarfs but more massive stars will necessarily become

massive stars will necessarily become

massive stars will necessarily become black holes but now the difference is

black holes but now the difference is

black holes but now the difference is the sun-like star will become white

the sun-like star will become white

the sun-like star will become white dwarfs but massive stars either they can

dwarfs but massive stars either they can

dwarfs but massive stars either they can become black hole or they can explode

become black hole or they can explode

become black hole or they can explode like a fireball the point is that either

like a fireball the point is that either

like a fireball the point is that either it can become black hole or it can

it can become black hole or it can

it can become black hole or it can explode so that became a big emotional

explode so that became a big emotional

explode so that became a big emotional upheaval you see scientists also have

upheaval you see scientists also have

upheaval you see scientists also have emotions obviously I mean we generally

emotions obviously I mean we generally

emotions obviously I mean we generally have the you know impression of

have the you know impression of

have the you know impression of scientists like you know mathematics and

scientists like you know mathematics and

scientists like you know mathematics and you know writing formally so scientists

you know writing formally so scientists

you know writing formally so scientists I didn’t assist so much but there is an

I didn’t assist so much but there is an

I didn’t assist so much but there is an emotional you know upheaval but there’s

emotional you know upheaval but there’s

emotional you know upheaval but there’s the first page article in New York Times

the first page article in New York Times

the first page article in New York Times Stephen Hawking accepted that in fact a

Stephen Hawking accepted that in fact a

Stephen Hawking accepted that in fact a singularities without horizons and do

singularities without horizons and do

singularities without horizons and do happen our one work

happen our one work

happen our one work happened over here in past many years

happened over here in past many years

happened over here in past many years they invited me to write an article I

they invited me to write an article I

they invited me to write an article I wrote one there is a Hollywood star also

wrote one there is a Hollywood star also

wrote one there is a Hollywood star also who was interested in stars and final

who was interested in stars and final

who was interested in stars and final fate of stars and she was very excited I

fate of stars and she was very excited I

fate of stars and she was very excited I want to be a rebel star I don’t want to

want to be a rebel star I don’t want to

want to be a rebel star I don’t want to a black hole you know agree I would like

a black hole you know agree I would like

a black hole you know agree I would like to sort of explored away so we had

to sort of explored away so we had

to sort of explored away so we had wonderful conversation and so on but of

wonderful conversation and so on but of

wonderful conversation and so on but of course despite being in Mumbai for such

course despite being in Mumbai for such

course despite being in Mumbai for such a long time I have not been able to you

a long time I have not been able to you

a long time I have not been able to you know attract any Bollywood star in the

know attract any Bollywood star in the

know attract any Bollywood star in the discussion of you know there there goes

discussion of you know there there goes

discussion of you know there there goes there go there goes you see the

there go there goes you see the

there go there goes you see the Hollywood then there goes the Bollywood

Hollywood then there goes the Bollywood

Hollywood then there goes the Bollywood the recent developments have been

the recent developments have been

the recent developments have been astronomers have never been asking

astronomers have never been asking

astronomers have never been asking because many groups have worked on these

because many groups have worked on these

because many groups have worked on these things and well so black holes are there

things and well so black holes are there

things and well so black holes are there and naked visible singularities are

and naked visible singularities are

and naked visible singularities are there what are we going to see out there

there what are we going to see out there

there what are we going to see out there can you observe something so there have

can you observe something so there have

can you observe something so there have been lot of developments on that much

been lot of developments on that much

been lot of developments on that much more interestingly the recent papers

more interestingly the recent papers

more interestingly the recent papers have come in fact in past few weeks and

have come in fact in past few weeks and

have come in fact in past few weeks and months from places like Cambridge and

months from places like Cambridge and

months from places like Cambridge and Princeton and you know top places in the

Princeton and you know top places in the

Princeton and you know top places in the world confirming that in fact

world confirming that in fact

world confirming that in fact singularities without horizons also do

singularities without horizons also do

singularities without horizons also do occur so that’s very interesting and

occur so that’s very interesting and

occur so that’s very interesting and satisfied you know whether I mean

satisfied you know whether I mean

satisfied you know whether I mean whatever happens whether they cite you

whatever happens whether they cite you

whatever happens whether they cite you where if they don’t cite you all those

where if they don’t cite you all those

where if they don’t cite you all those things things are fine but you know our

things things are fine but you know our

things things are fine but you know our work is well into discussion for quite

work is well into discussion for quite

work is well into discussion for quite some time because of the monographs the

some time because of the monographs the

some time because of the monographs the the Cambridge and Oxford and others have

the Cambridge and Oxford and others have

the Cambridge and Oxford and others have published but more so because of you

published but more so because of you

published but more so because of you know the Scientific American and Angela

know the Scientific American and Angela

know the Scientific American and Angela and Shelton like you know episodes but

and Shelton like you know episodes but

and Shelton like you know episodes but the sort of fade is intrigue Ewing why

the sort of fade is intrigue Ewing why

the sort of fade is intrigue Ewing why all these things are so important

all these things are so important

all these things are so important just a word on that you see when you are

just a word on that you see when you are

just a word on that you see when you are close to a singularity such high

close to a singularity such high

close to a singularity such high densities what happens is that the

densities what happens is that the

densities what happens is that the gravity forces and the quantum forces

gravity forces and the quantum forces

gravity forces and the quantum forces come together they work in unison

come together they work in unison

come together they work in unison otherwise we don’t have today a good

otherwise we don’t have today a good

otherwise we don’t have today a good theory describing the quantum gravity

theory describing the quantum gravity

theory describing the quantum gravity effects in you know unified manner in a

effects in you know unified manner in a

effects in you know unified manner in a satisfactory manner so if you can see

satisfactory manner so if you can see

satisfactory manner so if you can see the signals you see coming from this

the signals you see coming from this

the signals you see coming from this very dense regions or the singularities

very dense regions or the singularities

very dense regions or the singularities then you know you have a real hope of

then you know you have a real hope of

then you know you have a real hope of finding out we have string theories we

finding out we have string theories we

finding out we have string theories we have loop quantum gravity s but not

have loop quantum gravity s but not

have loop quantum gravity s but not really telling us too much so it is the

really telling us too much so it is the

really telling us too much so it is the unification of physics as a whole that

unification of physics as a whole that

unification of physics as a whole that is creating or making this as a really

is creating or making this as a really

is creating or making this as a really frontier problem it’s really like a mini

frontier problem it’s really like a mini

frontier problem it’s really like a mini Big Bang Big Bang singularity the origin

Big Bang Big Bang singularity the origin

Big Bang Big Bang singularity the origin universe origin of the universe you all

universe origin of the universe you all

universe origin of the universe you all have heard so if anacott singularity

have heard so if anacott singularity

have heard so if anacott singularity occurred then there would be a you know

occurred then there would be a you know

occurred then there would be a you know a blast like many Big Bang whenever a

a blast like many Big Bang whenever a

a blast like many Big Bang whenever a massive star collapsed purely under the

massive star collapsed purely under the

massive star collapsed purely under the pull of its own gravity and now you see

pull of its own gravity and now you see

pull of its own gravity and now you see this is the event horizon telescope

this is the event horizon telescope

this is the event horizon telescope which is going to see the center of our

which is going to see the center of our

which is going to see the center of our own galaxy the Milky Way so they are you

own galaxy the Milky Way so they are you

own galaxy the Milky Way so they are you know really trying to make the

know really trying to make the

know really trying to make the experiments observational missions the

experiments observational missions the

experiments observational missions the real you know quest is to understand the

real you know quest is to understand the

real you know quest is to understand the cosmos and here are the LIGO you know

cosmos and here are the LIGO you know

cosmos and here are the LIGO you know telescope arrays and gravitational waves

telescope arrays and gravitational waves

telescope arrays and gravitational waves could bring to us some of this signals

could bring to us some of this signals

could bring to us some of this signals here is you know a recent book that I

here is you know a recent book that I

here is you know a recent book that I wrote which describes many of this

wrote which describes many of this

wrote which describes many of this developments in quite some detail it’s

developments in quite some detail it’s

developments in quite some detail it’s it grew really out of the Scientific

it grew really out of the Scientific

it grew really out of the Scientific American article discussions doing

American article discussions doing

American article discussions doing frontier science in India how’s that

frontier science in India how’s that

frontier science in India how’s that like and I must say you know a couple of

like and I must say you know a couple of

like and I must say you know a couple of words here

words here

words here recently you know when key Ram Krishna

recently you know when key Ram Krishna

recently you know when key Ram Krishna has said Indian Science Congress is a

has said Indian Science Congress is a

has said Indian Science Congress is a circus and this is you see printed out

circus and this is you see printed out

circus and this is you see printed out there in a Hindu article and he was not

there in a Hindu article and he was not

there in a Hindu article and he was not afraid to you know say this in public

afraid to you know say this in public

afraid to you know say this in public is this all correct well there are a few

is this all correct well there are a few

is this all correct well there are a few good places you see in India where you

good places you see in India where you

good places you see in India where you can do some work so down good facilities

can do some work so down good facilities

can do some work so down good facilities and so on but really speaking barring

and so on but really speaking barring

and so on but really speaking barring you know few good places few places you

you know few good places few places you

you know few good places few places you can count on your fingers really ever

can count on your fingers really ever

can count on your fingers really ever you know universities are in Chambal

you know universities are in Chambal

you know universities are in Chambal sort of you know in a bad shape and we

sort of you know in a bad shape and we

sort of you know in a bad shape and we have to do something about it

have to do something about it

have to do something about it looking at our work own work objectively

looking at our work own work objectively

looking at our work own work objectively and effort you know it’s an effort to

and effort you know it’s an effort to

and effort you know it’s an effort to work at the frontier of knowledge they I

work at the frontier of knowledge they I

work at the frontier of knowledge they I must say that we have you know basic

must say that we have you know basic

must say that we have you know basic infrastructure problems so you run into

infrastructure problems so you run into

infrastructure problems so you run into those you have to take care of that I a

those you have to take care of that I a

those you have to take care of that I a need not go into nitty-gritty you know

need not go into nitty-gritty you know

need not go into nitty-gritty you know for the moment but we what we really

for the moment but we what we really

for the moment but we what we really need today is to solve this issue this

need today is to solve this issue this

need today is to solve this issue this is so many young people aspiring young

is so many young people aspiring young

is so many young people aspiring young people are there they are no less

people are there they are no less

people are there they are no less intelligent than anybody in the world am

intelligent than anybody in the world am

intelligent than anybody in the world am and I have gone to few countries several

and I have gone to few countries several

and I have gone to few countries several countries and you know then they deserve

countries and you know then they deserve

countries and you know then they deserve opportunities what is needed is

opportunities what is needed is

opportunities what is needed is attention on education and research and

attention on education and research and

attention on education and research and this is sorely missing the education is

this is sorely missing the education is

this is sorely missing the education is suffering in this country we need to do

suffering in this country we need to do

suffering in this country we need to do something really really drastic do you

something really really drastic do you

something really really drastic do you know revive and through it is your

know revive and through it is your

know revive and through it is your children your generation so it is for

children your generation so it is for

children your generation so it is for you really to take up you know all the

you really to take up you know all the

you really to take up you know all the responsibilities and do something about

responsibilities and do something about

responsibilities and do something about it you cannot say that oh we are all you

it you cannot say that oh we are all you

it you cannot say that oh we are all you know us-bound target audience well

know us-bound target audience well

know us-bound target audience well certainly you know some change may be

certainly you know some change may be

certainly you know some change may be there you know some President may come

there you know some President may come

there you know some President may come who we all know stay in your country so

who we all know stay in your country so

who we all know stay in your country so what are you going to do thank you

what are you going to do thank you

what are you going to do thank you you