we're now entering
the part of ada one which is the most
difficult for students and faculty alike
we're going to
and to the domain of angular momentum
and ports extremely known intuitive
the good news however is that we will
stage with this concept for at least for
quite a bit
today i will introduce
boast to work
an angular momentum
or they are meant to be even object has
amassed a m
and it has a velocity g
then clearly it has a momentum
that's very well-defined your reference
frame
frolic program
angular momentum
i can't take relative to any point i
choose ike
george this point q arbitrary
this now
is the position vector rhetorical are a
few
buttons and will be fade out
an angular momentum
relative to that point q it's a factory
idbi position vector relative to that
point q
crosby
so it is art
of q
cross
and then
content
the magnitudes
of the
angular momentum
wrote a quick to point killed
is of course are empty but then i have
to take the sign of the angle fade out
so and i think it is and the
clamped a tap
and this are often call shorthand
notation
are perpendicular
that's
or
perpendicular
if this distance
politics two points
what you just saw
may have confused you and for good
reason
because i changed by index q to see
and there is no seat
indexes shoe dolby too of course
so these are
in billings will be inspected it is the
magnitude of the inspector
so they should have a q
and all are a few signs dadar
which michael are perpendicular
must have
index q
and that is this barge here
yes and that is ninety degrees
and this year
zara
of q
perpendicular
no seasonal
only cues i'm sorry for that
the direction of the angular momentum is
easy you know how to
do across products
so in this case
art cross
would be
perpendicular to the blackboard
and the magnitude
is also easy to calculate
now coz
the difficult
problem with angular momentum
if i chose any point on this line say
point c
then the angular momentum relative to
point c
zero
very obvious because
the position vector art
and the velocity vector in this case at
the same direction so
vaidya zero so decide the fate of zero
so you may be seated angular momentum is
not an intrinsic property
over moving object alike momentum
which is an intrinsic property
if you sit there and twenty six one
hundred
you see in object moving with a certain
velocity because of certain must
you know it's momentum
what do you know i meant to be is
depends on the point that you choose on
your point of origin
if you have chosen disappointed me
that the anger momentum
what he can be
this way
because when you put here the
position vector
you know you see all across the
is now coming out of the blackboard
and that is why entitlements and
is such a difficult concept
but it was spotted in a way
but it will be very useful
suppose i throw up an object
twenty six one hundred
and that's when people's zero
you object is here
and the time ki
you object is there
so this man
is the
position vector
at prime t
the object
starts offers a certain velocity t
and a little later do you say
the velocity
is like so
and there is of course
force on it
and gene which makes these
what is the angolan two olympics two
point sepia time zero
yang implement them
scrutiny zero because the point itself
the mass itself is at point c
sort of position vector has no legs
so it's clear
attid zero
was the angular momentum at the time
talk to you when you object is here
well that and get a momentum
it's clearly mob zero
because you see here
position vector and you see the velocity
so clearly the angular momentum
was changing
now you both say of course it was
changing big a deal
because annual income has eight
velocity factory
and hear the velocity vector is changing
all the time
so obviously you would say
the angular momentum
changing
yes that is not a bad argument
but i will not show you a case
rehte velocities changing all the time
but where are you know meant that has
not changed
itunes
europe's going around to some
near the earth
mass and
a twenty year is the son
visit the position vector art
of c
and the earth has a certain tangential
philosophy
and this speech
never change its but the velocity dust
change
so this is the position vector
at a later point in time
what now is the angular momentum offbeat
both going around to some
relative to pointing out the casino
well that angular momentum
if i take the the magnitude of the
angular momentum
because the direction is immediately
obvious if the object is going around
like this this is the
position vector
the direction will be pointing out of
the blackboard that's easy
so i will get worried now about the
the magnitude
sort of magnitude is the
mass of the earth
times the magnitude
all the across product
between these two vectors
and noticed the angle is ninety degrees
so i can forget about the cross the
final status
and so i simply gets
the now being
the speech
there is a case where the object is here
but many object is here the situation
has not changed again
are crosby
the magnitude is exactly the same
because the site of the who hasn't
changed
until you see here ok so by the velocity
is changing all the time
but gentlemen the relative to points he
has not changed
suppose i'd chosen point q
is a little meant
them changing relative to point to you
better believe it
there is a time that you all get google
also point q
will there be a tremendous clearly zero
because that
position vector zero
if the object is here and you take the
and amend the relative to point to you
for sure
daniel meant to me is not zero
you have a position vector and you have
a velocity
so only
relative to point c
the very special case now
is angular momentum not changing
so enrollment in
is consumer in this special case but
only
point c
and i want to address that
you know they're a bit more gentle way
i take the exam momentum
i like it was a point q
and i know that the definition of his
position vector
fifty point q
crossed p
i think they're terrific
funded attitude
p l
the team
relative to that point cubes always
important that your state which point
you have chosen
relative to which it continued momentum
that is going to be
v_r_
bt
cross p
plus
or
of q
across
d_d_t_
is it that way
that you take the
underrated evolve across product
we calculate e angular momentum
relative to point q
so he index
has to be killed throughout the equation
position vector
relative to point q
and in this equation
you see the correct index q here you see
the correct index q here
but i slipped up here
and i put you see there
there is no seen this problem
so this is also
sorry for that
this here
is the velocity of the object
the velocity vector
which has always been the same direction
espy
so there's a zero
d_p_p_
that is the force on the object
we've seen that before in eight oh one
and so now we have that
the l_d_p_
politics to a point q
equals
the position vector art
from that point
cross-eyed
and this now
is what we call pork
and we write for that
the symbol tol
is effective
and i put in depth
pw again
and this is one of the most important
creations
that will stay with us
or at least
five necklace what it is telling you is
that
if there is a port
on an object
the annual mental must be changing in
time
if there is no to work on the object
and you know minton
will be
conserve
and now
you'll get some insight
into this situation that we just
discussed
the force you trekkie force
gravitational force
exerted on the earth
is in this direction
position vectors in this direction
so our cross-section zero
there is no pork relative to this point
c
but the angle between the two vectors
eight hundred eighty degrees in sort of
sign of the angle
is zero
therefore
no matter where you are on the circle
always are crossref will be
there is no port
relative to point c but if you take
foreign killed
or you take here some point katie
clearly but it's going to be
changing forty
and so there
you will have a change of angular
momentum
for something very special about that
avoca back to that of course
bout
i want to expand the ideal for angular
momentum
one point the object to that
moved in space
but all black like us to your work like
it did
which is rotating about
its central max
and i'll start with the disc
we have a disk
discuss matters and
and to discuss reviews are
and at this point c
is the central mass of these disk
it's rotating with angular velocity who
made up
and i want to know what the
thank element in this of this
rotating disk
the direction of the enrollment into
going to be trivial
it'd rotating like this
if you take it a little mass element
mass and levine
uses the
position vector are ironic that coup
d'etat point c
and here you have
the velocity to you via
but you see we need to get are crosby is
coming out of the blackboard so that's
easy
annual mentor will be in this direction
it was a magnitude
of the desk
as a whole
that's first calculate what gentlemen to
resolve this little nasa elements
about this point
so elsie
formats element hyatt
equals or let's just
only worry about magnitude because
already we know the direction
so that his alibi
and then the cross product to be arava
high-end he'll fly
but defenders ninety degrees so i can
forget about the
final fade out placing to get all of our
giovann
are apart
relative to that point c
of your party to the magnitude
so i hate to see if you buy in a
rotating disc because
the velocity
will depend on how far you are away from
the center
the velocity here is the road
however they're all have already gotten
common every single element that you
choose to disable may go so i'm always
going to be placed in a case like this
by omega are
and so this then becomes
and levine
or aren't
square here
and i guess
so i wrote down vehicles only guard
which of course holes in general
it would've been better perhaps it might
have
equals only god
but times are fine
because each
almond little alright
which has a position
is given by
bubonic
nichols omega
but i condensed it sort of in twenty
creating vehicles or make our
this is the connection that'll make it
perhaps easy for you
to understand will what's
so that is the angular momentum
for these little mass elements
but now i want to know
what the entire and a momentum it's
about that points to use an axis going
through the central meyer was central to
this group and if you look into
blackboard
and knock what i have to duty
summation of all these elements r_e_i_t_
ending the omega outside
and i would have been estimation and the
party
are applying relative to that point
since quit
and you should immediately i hope that
you see me deeply
that this is the moment of ownership
spin around sent off my ass
for that fluency
and so i can write for these by
we'll see
now comes the question to this is the
magnitude now comes the question
is these angular momentum
different
for instance for this point eight
and your first reaction will be gulf
coarse because
it depends on the point you choose
well the remarkable thing is that if you
have a rotation
about the central class which i have
chosen here
then even if you calculate the angular
momentum
relative to this point
or any other point even at this point in
space
you always fight the same answer
but only in case that there is a
rotation about
the central plains
and we call that this in angular
momentum
misprint angular momentum isn't
intrinsic property
of an object
regardless of which point you choose
what if it's too early to calculate the
angular momentum
during the case that
but object is spending about its central
last you're no longer have to specify
the point
that you have chosen your point of
origin
you can really talk now about
angular momentum
require is spreading
about its central mass
so depressed hasn't intrinsic spend
angular momentum in addition
it has a orbital angular momentum
if you want to talk about their orbital
angular momentum of the u_s_ however
you better be would want to give to that
point otherwise
it will be changing in time it's only
uniquely defines
if you take this special points
because only about their point which is
the location of the some
easy angular momentum orbital angular
momentum
both yours
i'm going to go daredevil experiment
with you
and that is gold
ice skaters the light
you will see that it is not a light at
all
but in any case it is
definitely
on experiments
i have here a turntable
very little friction
i'm going to work we'll take a turntable
about the center
and i'm going to stand on that
current able
idle holding my hands
to weights
it's about one point eight kilograms
so these waves and
one point eight kilograms
my entire mass including the turntable
and my body
but say is about
seventy five kilograms
and i'm going to ask someone to give me
a little twist
to rotate three
this axis oximetry
rotate me saying if you look from below
let's say i wrote my being rotated
clockwise
so we have your situation although a
location about the central laugh so we
can talk about
the intrinsic angular momentum off his
rotating system
andy
angular momentum bectero obviously be
pointing upwards
that's clear you rotate clockwise from
below
remember here you were rotating
counterclockwise pills coming out of the
blackboard you rotate clockwise
will be going up
so far
there is a force only due to gravity
and g
no concern
there is a equal lead
strong force normal force up in the to
cancel each other
once i had been given a certain
rotations are going to the velocity
going to put my arms and inform our arms
out and put my arms in
and when i do that
that does not cause a next toric
on the system
i can't keep doing it all the time
and there's no network
and so angular momentum
as we have specified for spending object
must be
concert cannot change
helical aren't
omega
but as i pulled my auditing
my moment of inertia will go down
and even my moment of inertia goes down
then if this product
has to remain constant
my angular velocity must go up
and vice versa
when i put my arms and i will go faster
and when i do this i will go slower
and i want to be a little bit
quantitated which you
all right
simplify my own boli
by but you have to go object
for which i can calculate the moment of
inertia which is a cylinder
i may not look like a cylinder
but close enough for practical purposes
and they said under has a radius
of about twenty centimeters
not too bad
uh... sort of fits me
and i'm going to wrote a piece of
america
about his access
and i can calculate now with the moment
of anniversaries distiller has a mass of
seventy five kilograms
as a radius of twenty centimeters
and so the moment of inertia
in this situation
that for instance i have the stool
objects
next to my body here
or have them like here to visit my
shorthand notation
equal simple
one-half
are square remember that was the
moment of inertia we discussed that last
time over rotating disc
which rotates
line chemistry
and so if i put in the numbers here
the seventy five kilograms
and i take a radius of twenty
centimeters
that i found that this is about one
point five
in our entry issues
now
i'm going to put my arms like this
and automotive inertia will go up
and i'll make a very troops calculation
how much it goes up
uh... my arm length is about ninety
senators
weightier are one point eight kilogram
so i just assumed that
the bar arms have no weights for
simplicity that all the way it is in
these two objects
it's a simplification but you'll see is
dramatic changes at all i wanted to see
so now the moment of inertia
when my arms are like this
of course
is my body
which is the one point five
that is still there but nowadays an
additional component
one from this mass
riches and are secreted
and one from this mass which is an are
spread where this is now
and raise our
and so i get
twice that mass
and that i have to take
r squared
which is over toward nine squared
and i have to take
the one point eight
that's the moment of ownership
obeys all jacked
about this point that is an are square
actually took my arm as no-man's
and when you add this up
you'll find
four-and-a-half
intently as units kilograms
you discredit
and now you see if i go from this
situation to base
my moment of inertia goes down by a
factor of three
my momma governor should go down by a
factor of three biennial velocity must
go up by fax for free
and vice versa
i want to do this experiment with these
experiments
is not without danger
uh... the problem with this experiment
is that the moment that you pull your on
them
you're getting the extremely busy
and you can lose your balance
and you can fall flat out on the floor
and i've just talked this morning please
some stories here we did that in high
school in
he told me that indeed one of the
teachers went flat down and i try not to
do that today
so i mean really assistant from someone
whoever who i can trust
i think i can trust you
that's a lot of time for u_s_ strongman
you can or can i trust you
the first thing i wanted to do
is to help me get on here because even
getting on here
is not easy if i just got on the other
probably falls
okay to stand there
which arm around my neck support me
strongly
all right there we go
or stay with me for a while
okay just stay there
all right
no you give me the reasonable
angular velocity whatever you think is
reasonable i'll tell you the completely
unreasonable
give me a bush
that's fine
while duties if i know you walk a little
bit away if i pull try to catch me
okay my arms goin out
armed guards
empyrean
arms go out
okay now i'm completely busy now it is
no joke to stop me
this hold it
but this whole the whole time
okay get my hands
okay you pass the course
now
sacrifice for the sake of spying org
alright have done worse
if we have a
collection
off ninety points
likely already discussed with firm
momentum
warns that interact with each other
recording stars
gravitational even track
could be object was i connected which
plagues
they had internal interactions which go
on all the time the balance of the
charter they collide
they break up into pieces
internal friction or anything
if i take it to all of these objects
if this one for instance
is attracted
towards this one
and action equals miners reaction
and these two forces
identical in magnitude
so it might take any point q if you no
matter where you choose it
that will never opposed
support on that system
because the two forces cancel each other
out
and so now what we get the
final
consultation of and your momentum it's
all its glory
if only we adhere
little word
external
uh... you know mental of the system
this whole dang element that will just
one object
you getting them and what was his
troubled many particles they could be
connected with springs
there could be chemical explosions going
off they could
plowing to each other they could break
each are up
angular momentum will not change
if there is no net external port
on that system because all the internal
pork sports cancel out because action
equals minus reaction
so every now
compare cultivation of angular momentum
responsibly to build momentum
it in the case
off the conservation of momentum
remember when we had a system of objects
in the absent also and external force
on the system as a whole
net external force
lamentable spinster
now we have
with a system of particles in the
absence of open yet
external pork
annual meant to be sir
in the case
of the
ice skaters the light
when you pull you aren't in
the moment of inertia goes down
and so you're free concert goes up
when a star shrinks
israelis goes down
its moment over nisha goes down
and therefore
it's angular velocity
must go up
moment of inertia
goes with are square
what determines besides off eighty
this is a start
that inside this targeted furnace no
career furnace
nuclear
pure which is going on
that produces
and pressure
which wants to expand to start
on the other hand
there's gravity
recess or in
you can do that
i want to
altogether
in fact gravity would like to collapse
the start
and nature
finds a balance between
the gravity and its pressure to three
the nuclear furnace
nada comes a time
at the nuclear for in this has been
completely
consumed
for some the takes an additional five
billion years
wilson has already being earning
nuclear fuel for five billion years
cudlow five billion
and once the nuclear fuel has been
consumed
their art
three and products
of the
dad star that is left over
and these three and products
are the following
number one
it's called the whitewater
it has a radius approximately the same
as the arrest them
ten thousand kilometers
and the mass of a whiteboard
as a whole range of them quit a typical
number say
is hop classical some
but what possible info
this'll be the faith of our son by the
way
the density of such an object is quite
high intent to do
will be roughly ten to two sticks grams
for cuba kennedy
another possibility is
that you end up with a neutron star
neutron star has a radius of about ten
kilometers
moments
and it has amassed
of roughly
one point five times the mass
uh...
and its density
is about ten to fourteen grams per cubic
centimeter which even higher
the density of nuclei
and then there is a possibility
which is even more bizarre
that you end up
with a black hole
i will not talk about black holes today
but i will get back to that later
in ada wong
and the black hole
for all practical purposes
has no size at all
the mass of the black hole
must be marching band
we think three solo masses
and so the density
is infinitely higher
well you and up to be a wide we're going
to post or a black hole depends on the
mass albeit will be
po genital thus far that collapsed when
if you will nuclear fool's gold
that in order to form a new twist or you
would have to start off
which is far off probably at least ten
solo masses maybe even more
to our son will not
become a neutron start
what are some who ultimately become
a whiteboard
it'll be a reasonable question to ask
why do you and other only with the three
possibilities why is there nothing in
between
looked at as a huge difference from ten
thousand kilometers
franco want to be done nothing in
between
and the answer to that wisely quota
mechanics which is not part of the
scores but you will see that the nato
fight
why don't we do still
and then if you get into a general
detained at the
then you will understand
that is then the spirits
very bizarre possibility
when a star collapses
two things happen
first of all
there is a huge amount of gravitational
potential energy that is released in the
form of connecticut
the stuff for them to call a
gravitational collapse and that
gravitational potential energy converts
to connecticut maji and that ultimately
converts to heat
and to radiation
if i take an object here fees of chopped
and alright dropped that
that you can call gravitational collapse
gravitational potential energy is
converted to connecticut energy
and ultimately
it goes compete
here we're talking about the starr which
is
imploding
collapsing and the amount of
gravitation potential energy that become
available
enormous
in addition so this huge amount of
energy released
the star must pin-up
because it's
moment of ownership
goes down
and therefore
the angular velocity
i want to do a little bit of qualitative
work on this
and i want to take on the object
like our son
and i would like to collapse that object
from its present radius of the song
which is about
seven hundred thousand kilometers
i want to collapse that we don't want
start
with a radius of ten kilometers even
though i know and i told you that the
sun will not be calm
neutron star
it just to get some feeling for the
numbers
so we take an object like the song
because the radius
of about seven hundred thousand
kilometers
and we're going to collapse that
crew notes from starr which has a radius
of about
and come up
the mass of the sun
is
to content of the thirty kilograms
and for those of you we're good at math
they can calculate
when you collect his object without
losing any master people the mass return
shrank at the temple on others
holographic ayesha potential energy
is released
and that is a staggering number
and i called at bell thank you
it is a loss
of gravitation potential energy which is
about
ten
food corti six jewels
and his number is truly
mind
boggling
this is converted to connecticut energy
and that it is concluded
complete and all forms of radiation
daniel feeling for how absolutely large
these numbers
if you take the sun
and you take all the energy that the
some producers its
ten billion years that it will live
the total energy output oldest son
is hundred times less than this number
and this comes out in a matter of
seconds
so it is a
mind-boggling idea
that the solace producing in ten million
years the lifetime of the some
it is producing
less
energy
what happens doing this fella collapsed
to anu kmt star
hundreds tons less
so let me the info careers and this huge
amount of energy is released
outer layer bunches off in the court
and he's expelled
and that's what we call a supernova
explosions
outer layer of thrown off
free speech typically some ten thousand
along with this
for seconds our son will not become the
new point start
but it will become a
whiteboard
we talked about the crab nebula next i
left i mean the crab nebula is a remnant
of a supernova explosion
which of course believe it or not
on the fourth of july
india thousands fifty-four talking about
fireworks
this supernova explosion
was noticed
bite chinese absorber astronomers
they call this against start
chinese astronomers were very
prestigious
the reason for that was that these
chinese astronomers
advice the emperor
they look at the sky
and data right
from the sky information at full speed
forty-a they knew how to interpret
occurrence of comets
or for instance
shooting stars or a particular lineup of
planets and suddenly the appearance of
the gas start
and they won't know that for instance
the public in a certain part of the sky
might mean that that would be underwear
that would be diseases that would be
fanning
or it will be a good time for a better
look would be a bad time for battle
and that's what these people were doing
that with fighting
the emperor
and therefore they were keeping a very
close
five discard no
when in flight
this star
was visible for weeks during the day
when it exploded
and it was the brightest star in the sky
years to come
it is a complete puzzle
why don't you think the single reports
by an
european astronomer
on your current of the supernova
thousand fifty four
it is very possibly
well you can argue that in the
netherlands anant england they're always
cloud has always raining so you can see
this guy okay i grant you that
but then we had a really and we have
sprained with a friend
and it is very strange it must have been
a cultural thing somehow
indianapolis century
somehow
europe was not interested in looking at
the sky because something they could not
have missed
but they didn't write it down
i know i want to pursue the spend up
over the start
when it collapsed this
from seven hundred
thousand kilometers to
ten kilometers
if we're out of the numbers off a little
bit
then the reduction in radius is about a
hundred thousand
it's really only seventy thousand of
that just make that
a hundred thousand sent to the states
that means are square
goes down
by factor of ten billion
a bar square goes down by a factor of
ten billion
then the moment ownership goes down by a
factor of ten doing
and told me got must go up
by a factor of ten billion if you
started off with the start
that rotated about its own actions in a
hundred days
he'd end up
rotating around
in guam many seconds when it has become
neutron star
a new phone start ten kilometers
has about the same out of the son of
little more
and it spins around
it warminster at the cradle of the notes
from starr
you reach about twenty percent
of the speed of light
reno hundreds of local stars in the sky
two of them have in fact
rotational periods
one-and-a-half
milliseconds many of them
much slower and we discussed last time
why that is because remember in the case
of the crap pulsar
the pulsar slowdown nature
is tapping on the rotational kinetic
energy obese pulsar's and is controlling
it
into other forms of energy
in the case of the crackle start
radio emission
optical emission gamma rays
x_-rays and even
jets the crap possible slowing down
every day
six point four natos seconds
bridge laughter was battery power out
for i still remember the number i think
sixth i'm tempted to thirty-one what's
in seventy five years the pulsar slows
down by one twenty seconds
sort of thirty
three milliseconds would become
thirty-four midi seconds in
seventy-five years
if the start of the original
there's no started was a described if
the start of the regional magnetic field
which mostar's do
i lost my star but that's okay
then in the collapse the magnetic field
will become stronger
and this is something you learn about an
eight oh two white become stronger so
most of these neutron stars have strong
magnetic fields
and most rotate very fast
and for reasons that we don't quite
understand
many of them blink at us
they blink at us
in radio
we believe that there are two
the angel radio mission like a white
house going out for me
commitment of both of them from start
and at the neutron star rotates
and you are on the wrist
it its rates over you
you see radio mission radio mission you
see nothing
to radio mission use your radio mission
too many pollsters
who's been doesn't sweep over the earth
we would never be able to see of course
and indicators of the pulse of the crap
it's even more special
because battlestar
also blinks adults
eg optical
x_-rays and in
the government's
and so now i would like to
show you
some slides
and discuss in a little bit more detail
the supernova
explosions
and the
fabulous lightzout hoops
and the sped up
so i have to make it quite dark
make it completely dark
and sort of for slides
is simply a artist conception
olympic distance seriously
all of these
beams of radio emission
busy then the rotating neutron star
and if the axis of rotation doesn't
coincide reason magnetic
doc alexis and if you have these
radio beans which we do not understand
how the affords
that you can see when they're okay tony
can't sleepover
now you may say well that's a little bit
artificial
because
uh... why would the axis of rotation
be different from the
magnetic dot collections
well that is not an exceptional in
astronomy
universe itself
as a magnetic type alexis who does not
coincide
with the axis of rotation
effect almost all the planets in our
planetary system
heavy magnetic type alexis
which makes a large angle which the
excess of rotation so that's the rule in
astronomy rather than the exception
even though it may not be easy to
understand that
and these blue lines then represent but
yet it feels minds
you'll see more of them then you like
when you take
and hear is
joslin belt
joslin bell was a graduate students
on the anthony you wish in cambridge
and she discovers
pulsars
funky the radio data
which were okay
using an no telescope that
anthony you wish
had built
she found in there
periodic signals
forces if you want to call them
you see some of them here at the bottom
and there were one point three seconds
apart
and she reported that two antony
and anthony said well they've got to be
known since of course
we there's not an object in the sky that
is going to
davis pulses was a separation of one
point three seconds so they just assumed
that it was caused by elevator
five maybe
milking cow machines or things of that
nature motorcycles and so they did every
conceivable thing
whether indeed this most amendment
phenomenon
they could not find anything and it was
jostling
who were incredible brilliance
able to convince antony
that indeed basis
object
that is in the sky and that the
radiation doesn't come
and when they've realized that
they realize that this will be the
discovery off
not only the century but of all of
mankind because they set
well who could possibly
send radio been set us and modulate than
with a period of one point three seconds
only intelligent life can do that
and so they called the espresso object
little green men
but just before they published
they discovered it in nineteen sixty
seven by the way
they found a second
all-star which had a slightly different
frequency
the one point three second period and so
then they realize that it was probably
not intelligent life
but that it was an astronomical object
so they gave that second object the name
little green men too but they abandoned
that idea
very quickly
welcomes the sad part of the story
in nineteen seventy-four anthony you
which was awarded the nobel prize for
this discovery and joslin who more than
deserved it
who really wants to discover who was the
person
will prove that this was astronomical
did not share
nobel prize
it is upsetting
if you said
i discussed it with joslin several times
i know we're quite well
and she takes it actually very likely
to life and i think
uh... still people few unhappy about it
and still after so many years the nobel
prize was awarded in nineteen seventy
four
everytime
that i think about this magnificent
discovery and i think about joslin i
think about these gross
injustice
here we see the crab nebula again we've
seen it before
draft elements that you see here
are the result of matter
that was blown off
when the implosion ocr twenty out early
response often in the court
and originally they had a speed of about
ten thousand
calamitous per second
and i know it is about starting to use
later
the speaker
we do it as being reducible
here at the center ccd
also ran last time i showed you
convincing evidence
that this is the poster because it's
blinking at us
because a dynamic of about seven
mightiest
it is a distant from myself about
five thousand light years
in terms of anglicized into skype
it's about five arguments in size which
is about one six
of the
angular diameter of the moon
this is a brawling caved rolling made by
navajo indians
and some people have speculated to what
extent
the navajo indians may have seen
discipline over eight thousand sixty
four is on clear but it is a possibility
the mood certainly get very close to the
supernova
but also got very close to penis
business something that is not wellness
coverage but it is a possibility
here you see galaxy
in which case open overall kurtz
and read a supernova occurs at its
brightest
it can be brighter than all come to a
billion stars in the galaxy that's how
much energy is released
it optical lights
you see edits
is at least as bright as the
anti-narcotics
on this picture for this picture is
about one year
useful curve in nineteen seventy two
and over a period of one year
you can still see this
star quite clearly
but it has been innocent strengths
and that everything happens
in february
nineteen eighty-seven on the twenty
third of february supernova went off in
the large may come in the clouds which
is a
satellite galaxy to our own galaxy
traditions of about how much fifty
thousand light years
and that wasn't astronomer who was
observing
south america his name is yun
sheldon
and king left dawn to look at the stars
and he decided
to take a peek out site
and as he was taking a piece with his
own words you looked at the large megan
and the clouds
he's fifty
that is funny
at star is not supposed to be there
what the discover
what is now known as nineteen
seventy
enormous supernova
going off so close
to where
and next slide shows you the same
portion of the march magnetic clouds
you can clearly see that there is a very
bright start eclipsing businesses naked
eye
this is a picture
made by the hubble space telescope
supernova nineteen eighty seven eight
inner ring that you see
is the result
never
that was thrown off
this stark before it went into supernova
explosions and twenty five thousand
years earlier
expelled
a_t_t_ crater uses media circles all u
looks like it now that's because of the
protection effect
and this
ring of matter moves out with the speed
of about eight kilometers per second
and
because a radius of about eight like
months
and so eight months after the supernova
explosion
ultraviolet light in the x_-rays from
the supernova caught up with his
wrinkled matter
date excited its and it became visible
before his supernova explosion
we are expecting in a few years about
the matter itself
that was thrown off with a much more
must be talk about ten thousand
kilometers per second
for that matter will also call into the
swing and then we expect some real
fireworks
there is no explanation that people
agreeable
for these two cole all-black rings
they're quite mysterious
and their papers written on its and
people disagree
supernova explosions
in our galaxy
and in d
was made in the clouds
are quite rare
re expect no more then about wong
install hundred years
the previous one that could be she was
naked eye
was in the year sixteen oh four export
dept or supernova
a nineteen eighty seven it was really
the first
that could be studied with modern
equipments radio observatories x-ray
observatories in orbit around
with some luck you may see a supernova
explosion naked eye in your life to
chant is no better than ten percent
so maybe it will help people casually
you take a peek outside and you become a
famous hasn't sheldon did we've now very
famous men
