[MUSIC PLAYING]
PRESENTER: [INAUDIBLE] to
welcome you here this afternoon
and to introduce the second
of this year's Killian Award
lectures.
Last week, I took a few
moments to make some remarks
about the award, the
man for whom its named,
and about the current recipient.
And those of you who
may have missed those
will have to look on
last week's videotape,
because I don't intend
to repeat them today.
Let me just again
briefly acknowledge
the presence of
Dr. James Killian
here, the man for whom
this award is named
and in whose name it is given.
And with that, I
look upon my function
largely to fill the few seconds
it takes for you to quiet down
in your seat, and then to
introduce the speaker today,
Phil Morrison, who will
turn on the fireworks.
Phil.
[APPLAUDING]
MORRISON: Thank you.
Dr. Killian and
friends, last week I
indulged in a rather
complex structure of talk,
which contained some
account of public illusions,
some account of the dreams
and hopes of the physicists,
and some of the problem of
education, which might help
to bring these things together.
So it was a kind
of dance of ideas
and could exhaust none of them.
This afternoon I'm going to
give a much more focused talk.
We'll still be very much
a cavalier dismissal
of a very large and
important subject,
simply on grounds of
time and preparation.
I think it's an appropriate one.
It just occurred to me sitting
here that the time during which
these notions have principally
developed-- of course
they rest upon a
very old foundation.
They are principally
developed since essentially,
the very year that I came
as a faculty member to MIT,
more than 20 years ago.
And most of what I
will do this afternoon
is to make a very
broad brush account
of the progress of the
astronomy of very deep space,
galactic astronomy.
Not on the one
hand, the cosmology
of the universe as a whole,
about which I said something
last time, nor on
the other hand,
the exciting discoveries
about matters closer
at hand, the stars
and the planets.
On the contrary, it's
that middle range--
it's quite a deep range--
which I shall address,
because here we
have come into
what I think can be
described in a very interesting
and simple way, which
makes some essential
points about understanding
and our lack of understanding
without much regard
to the great detail.
I should hesitate to
talk without beginning
by saying that most
of what I have to say
is based on the results
of experimenters,
what in astronomy what
are called observers.
But really, experimenters
who are provided
with equipment and with
understanding of what it means
and how to use it by physics.
It comes out of physics.
It is the physics
applied to astronomy.
The theoretical ideas,
which these induce in us
and the explanations we give
are so partial and immature,
as highly to be worth
designating with the word
theory.
And you'll see throughout
that it is primarily
we are led by what we see.
And we cobble up some
kind of explanation
to try to make sense of it,
given the strong understanding
we have of the principle
nature of forces and matter
that we can deal with
in the laboratory.
This is quite distinct from
the other great frontier
of particle physics,
because there are so much
beautiful detail is known.
And there, the system is
intrinsically, as we believe,
simple and elegant,
can be described
by a few mathematical
formulations.
And an algebraic
group or two can
be found, which will say
a great deal about these.
But in the domain of the large,
which you're here engaging,
that doesn't seem
to be true at all.
The variety of possibilities
that lie implicit
in the physics are very great.
And which one has been turned
on by the circumstances
of their origin is more than
we can imagine until we see it,
because you can do
almost anything,
shuffling the cards dealt
by Newton and Einstein,
by Alfvén and
Dirac, as you will.
And these are what we see.
So I shall have
to say that here,
observation and experiment far
lead theory and prediction.
And the over enthusiastic
notion of doing experiments
to test discriminate
between hypotheses
is very hard to
come by in astronomy
and generally doesn't work.
It turns out, the third leg of
the fork is what you wanted.
The third tine to
the fork, and neither
are the ones you
were discriminating.
And what we primarily
have done is explore,
but this explosion's
very exciting.
It's not without its rationale.
And I shall try
to point that out.
But that's really
what is involved.
I am hoping to leave
you with an overall view
of very strange circumstances,
which I think are,
as they might be hoped to
be, significant for everyone
entirely apart from the details,
as part of understanding
of the world in which we are.
Now, I'm going to
begin with a picture.
So if we can have
the first slide,
I think that would be very nice.
And then we'll follow it with
a few slides rather quickly.
In between, I might turn
on some of these notes
to make some sense of it.
I hope you can see this slide.
Maybe for this one,
which is rather faint,
we could kill off at
least one of those lights.
Can you see that slide?
It's supposed to evoke.
I hope you can see the reddish
color at the horizon and--
excellent-- in the sky.
Thank you.
It's supposed to evoke a sunset.
And in that sunset, which
stands and will stand.
And I will close the slide.
Something like this will
stand throughout for that kind
of warming hearth by which our
life is made here on earth.
That is to say, the light
of the star, the Sun,
to which to some
degree we belong.
We dwell in this hearth.
We are nurtured
by that sunshine,
as the Earth has been, its
curious fabric of living matter
for pushing for billion years,
and billions of years yet
to come.
But there is something else,
of course, in that picture.
It's not only a sunset.
It's a sunset,
which marks a line.
The line is not drawn, but
the line can be evoked there.
These three objects and
the sun, which of course,
the horns and the moon point.
The bow is being drawn by
Diana aiming at the sun,
just below the horizon
here somewhere.
So you see four points
make a straight line.
Well, I know it's not
a very straight line.
But it's good enough
for astronomy.
And it is, of course indeed
rather a nice straight line.
In some ways, it's the
marks a cut through what
we call the plane
of the ecliptic.
And the greatest commonplace.
By the way, it's
delightful to see,
and can be seen in clear weather
all the time now at sunset,
at least a little bit, whenever
the moon is toward a new phase,
because Venus has
been conveniently
there, and mercury, and from
time to time, even Mars.
So don't miss looking
for this order
if you haven't
seen it frequently.
But now, let me go to another
example in the next slide.
Shows a very different
straight line.
I think you recognize it again.
This is kind of a blurry picture
of the woods around the camera.
And this is a wide
angle camera view,
emphasizing the Milky
Way with its curdled
and dusty looking appearance
going across the slide.
Another straight line.
Very interesting.
And, next.
I deliberately chose
these two pictures
to be about the
same orientation.
They are looking about the
same direction in space,
with respect to earth and Sun.
And this however of
course, is a map.
It is not a photograph.
It is a computer
generated, color coded map
of the observations made by a
wonderful satellite a year ago,
the IRAS satellite, looking at
the same direction from orbit,
with its cryogenic
infrared eye looking
at the center of the
galaxy, which is in there.
And it has something
like the same scale.
This is a big swath of the sky.
And across that
swath of sky goes
this wonderful straight ribbon.
And the color coding just
tells you different intensities
and different wavelengths.
The infrared not relevant
to my purpose at the moment.
You can simply say that
there is a layer, which
is able to emit
lots of infrared,
dominating the sky brightness.
And that layer is a flat disk.
And of course, the
other flat disk
is the layer of the planets
of the solar system.
When you cut it either
way, you see just a line.
And of course, that's
a typical situation.
Now, this is a much better view
than we got with the Milky Way
from Earth because you
don't see very far.
You're not seeing a depth.
You're seeing only
the nearby stuff
that tends to hang
in that flat disk.
And of course, nearby
its size bulks large.
And dust is in the way.
But infrared is penetrating.
It goes right
through the galaxy.
And it gives you a
view of distance center
with no great problems at all.
And you see again
how flat the disk,
or if you like, how straight
the cross-section of the disk,
as we look there.
And I think that would be--
no, I think one more
slide at this point
is worthwhile making.
I want to add just
one more element.
Really, I think I'll wait.
Lights.
I'll come to the next one.
Now, what I've said
so far is simply
that we live in what I
would like to call Gush.
No way is that readable.
I like to call that a hearth.
We live in the hearth in
front of the hearth, which
is the Sun.
Of course, we have
grown to live there.
We couldn't live anywhere
else really, not very well.
And so it's no wonder
we are superbly
fitted to that environment
by a long process, which
is not my purpose to describe.
Now, I would like
to go a little bit
from these broad
observations, which I
think justify what I'm saying.
To try to do so with
physics, I must do that.
The physics I will
take is really
drawn from the laboratory.
Of course, it requires
a lot of maturity.
And I shall simply skip that.
I'll simply assert it.
And I believe most everyone
will know what I'm saying
and feel that it
is probably right.
But I could of course,
demonstrate it similarly,
interestingly from the lab.
But I'd rather say this is what
the theorists know as result
of laboratory experience.
What are the forces
that we look at--
whose work we look at?
We look far away out into
the universe, even as far
as the planets.
Even indeed, as far as our
own lives if we drop a ball
or walk upstairs.
We're engaged, as we know,
with interaction with the Earth
as a whole.
The gravitational force that
was recognized and characterized
by Newton.
Now, why is gravitation
the dominant force
we're going to consider?
It's negligible
in the laboratory.
No protons practically have
ever heard of gravitation
in the accelerators.
They could hardly
be expected to.
Bulk matter, yes, it
knows it very well.
But individual particles,
hardly at all around here.
Now, of course the
answer is quite clear.
And I simply want to
emphasize everyone knows this,
but I just bring it forward.
It's the basis all
I'm going to say.
Gravitation is an
insatiable force.
It's unstable.
It wants to grow at the
expense of its environment.
Any gravitating
center-- of course,
we know that
gravitational force is
proportional to the
product of the two masses
that are engaged.
That's the familiar formula
from elementary physics. m1 m2
over r squared, and so on.
And of course, if I imagine
that I satisfied the force
and let some matter
fall in as attracted,
what happens to
the force center?
Why, it is reinforced.
It has extra mass,
and so it grows.
And in this sense,
it's insatiable.
The physicists say it
cannot be saturated,
which is just another way
of saying the same thing.
On the other hand, if we have
electromagnetic forces, which
as everyone knows are intensely
stronger particle by particle--
for example, in the atom, I
blanched to use the number.
In the atom, they're
10 to 38th times
stronger than the gravitational
forces [INAUDIBLE]
electron and proton.
So it's no contest.
And on the other hand, they
have an extraordinary property.
They are not insatiable.
In fact, they saturate
at once, for two reasons.
First, because the
nature of the force.
The second, because
a quantized nature
of charge, which comes in such
limited numbers is just plus 1
and minus 1, and that's it.
And none, I suppose.
And the plus minus cancel, so if
I have a positive charge, which
attracts unlike
charges and draws
in opposite draws
in a negative charge
down the potential
slope, of course
it gets a little negative.
But since it was positive,
getting more negative,
it's not as strong
as it used to be.
If it gains again, it will--
and in the end, it has nothing.
And so if you pile up
matter, unless you're
extremely powerful, when
you pile up a lot of matter
it will have no important
electrostatic force left.
They'll have big
gravitational force
left because the plus
and minuses will cancel.
But the tiny gravitation
never cancels.
It's always augmented.
And of course,
that is the reason
why the universe is dominated
by gravitational forces,
since it consists of very
large pieces of matter
from our point of view.
This is always
spoken from r equals
zero, our center, our position.
Now I will say,
however, that if you
have electromagnetic forces
in the broad depths of space,
which you are examining.
You should remember also that
the current, which is present
whenever matter is present--
can be present whenever
matter is present.
And we'll see, especially true
in the highly charged highly
ionized domain of space.
If currents move, they tend to
short out electrical fields.
That's just the argument I made.
They move towards down the field
and cancel when they get there.
On the other hand,
those very same currents
nourish the B field,
the magnetic field,
because it is current that
makes B field, and not charge.
So even if I have equal
and opposite charges moving
in equal and
opposite directions,
cancels out charge wonderfully,
but only augments the B field
splendidly.
So the B field indeed is the
only product of magnetism
we will see.
We have, perhaps the most
interesting arguments
of not the last 20 years,
but the 20 years before that,
in all of deep space astronomy,
where the demonstration there
were indeed extensive
magnetic fields in space.
And I shall drop on that later.
So that's what the forces are.
And now, if you want
forces on charges,
if there's no
electric field, then
the forces of gravitational,
which are small.
Or if you have
individual particles
and a B field is
moving by, you can
take advantage,
broadly speaking,
of what is called the
Lorenz force, the velocity
dependent force, V cross
B, which works on a charge.
And the physicists
will know right away
that that's what goes
on behind the motion
of individual charges,
should we ever
see such things in the
course of our studies.
Now, it is appropriate,
having discussed the forces,
also to mention the forms.
And here, I think I'd
already given the forms.
And I will just uncover
the discussion that I want.
Of the forms, that means
geometrical forms under which
these forces exist in space.
It's a very old and long
established proposition.
The first form, of
course, is the sphere.
And the sphere because
it has no orientation,
is a sign that random
motion is there,
struggling against
isotopic, every direction
the same gravitation.
Gravitation is a central force.
It draws toward the center.
The sun draws its planets.
The earth draws
everything on its surface.
And the bodies are
beautifully spherical.
And the moon in
the first picture
was spherical, only half
illuminated by the sun,
quarter illuminated as you saw.
And you know very well,
this is the phenomenon
that all the objects that are
sufficiently large and thus
dominated by gravitational
forces are in fact spherical--
all the nearby objects.
Now there is, of
course, something
to be said against that.
It's very nice to have this.
By the way, the random motion
in the case of the sun,
we know it's the gas pressure
of the hot gases within the sun.
Very reasonable.
And we'll see other examples.
The what I now
call and intend to
call the disk, that
is the flat plane
in which the planets move,
and which the galaxies
material seems to be gathered
preferentially together.
That disk is a two
dimensional motion.
The planets orbit.
They do not whiz up and down.
The axial velocity
has disappeared.
And this must be a
historical thing.
And now you see we've come into
the problem of history, which
will dominate this
entire first discussion,
because why should they not
have motions in all directions?
Well, we begin to see now.
We can see that if you have a
system, such that it can lose
axial motion, it will not
fall in by that virtue
because it is only the motion
in the plane at right angles
to the axis, going through
the revolution and axis
that keeps the thing in place.
So if you don't lose that,
you'll still stay in place.
Yet, you will change from the
three dimensional randomness
to a two dimensional flat
plane, a phenomena which
seems quite important, since
it dominates many skills.
Already we've seen it
dominates the solar system's
planets, the orbits.
And it dominates the orbits
of the stars and dust
that make up the vast
plain of the Milky Way.
They're very striking,
but that should be seen.
And these two forms, sphere and
disk then acquire their realism
from this argument.
And to go a little
further into mechanics,
I will say, all right, here is
meant to be a random sphere.
And I can characterize
that random sphere
in a very nice way by using what
all students and mechanics will
recognize as the Virial theorem.
I just don't worry
about the name.
A fine old Latin name.
The kinetic energy is about
equal to the potential energy
for any system held
together by gravitation
that is in a steady state.
And that's what we find.
So if you have a lot of
particles moving about,
they better have as
much kinetic energy
as their gravitational
attraction.
And if they do, they'll
be able to withstand.
Otherwise, they'll
collapse or blow up,
do one way or the other.
So steady state is
going to require that.
And this, of course, is--
in a way, you can say this
is why the sun is hot.
Or if you like, you can say
that because the sun is hot,
it must be bound by a certain
amount of gravitational force.
Gravitational force
is very large.
That makes the sun very hot.
Or either way, the
two are related.
And this is the way that
the gravity is fought
by random undirected motions.
You see, gravity being
insatiable must be fact,
or otherwise the world could
collapse to a single point
somewhere.
And what has beaten that
back is in every case,
some kind of motion.
Perhaps not so on the very,
very lowest level of size,
where perhaps the actual
repulsive forces might exist.
But barring that
small exception,
it is really motion--
motion in the sun, which is gas
pressure, motion in the galaxy,
which is the sub orbiting stars,
and motion in the solar system,
the orbiting planets.
And in every case, it is
motion that inhibits gravity.
There is no such thing
as a shape, which
is not connected with motion.
Aha, you say.
The Earth itself is a sphere
and I've suppressed that.
But, of course, everyone
recognizes the Earth is kept up
by the forces in solid matter.
And those forces, indeed, are
also primarily random pressure,
not however, due to the
thermal motions so much,
as to the repulsive effect
of the overlapping electron
crowds and atoms
that prevent matter
from collapsing onto itself.
I shan't discuss that very much.
But that's often called a
Fermi or shredding of pressure,
which does the same job.
In any case, that's what it is.
I mentioned one other
important point.
We know in mechanics, the energy
as a constant of the motion,
we know the angular momentum
as a constant motion
of vector constant
rather more complicated
and it's playing
that it is keeping
J, that requires these
particles to stay in this plane.
They don't fall in
because they would
have to lose any momentum to
do so, it's very hard for them
to do that.
It's much easier to lose energy
than to lose any momentum.
Indeed it turns out that these
properties I'm describing
are properties of a gas and
many interacting particles
and perhaps that also is
the origin of this form
both in the galaxy and
in the solar system.
I don't press them too strongly.
Now the next thing I
would like to describe,
because I must have a
background for pictures
I'm going to show you,
are the substances
of which the world is made.
Now above all the world is
made of hydrogen gas, wherever
we look that's what we see,
it was first brought forward
in a brilliant PhD thesis in
1925, by Cecilia Payne, then
a graduate student at
Harvard College Observatory
and this perhaps most brilliant
of all, astronomy PhD theses.
She concluded that
the world indeed,
with the sun and the stars in
mind, were made of about 90%
hydrogen and cautiously she and
her advisor added well perhaps
there's something wrong with the
story that seems so incredible,
but that's what the
calculations suggest.
By now it's been
enormously confirmed
and we know that all
that we see in fact
is made of hydrogen. Hydrogen
has many different forms,
I mentioned them, there's even
another one I didn't mentioned,
as being too complicated
but hydrogen metal,
let's let it go.
We have H2 molecular hydrogen,
very significant in the galaxy.
H neutral atoms of
hydrogen also quite
significant in the galaxy.
And separated hydrogen
atoms, e minus
p plus, drifting
about which we might
call hydrogen plasma or
ionized hydrogen, also
quite significant.
Now, I want to point out, of
course, that gas is lassy,
gas loses energy, doesn't keep
it and radiates, in general.
Turns it into photons
and emits the photons.
This is how we can
do astronomy anyhow
but of course this loss of
this is very characteristic
of gas, that's not true of
the Earth's orbital motion,
for example it's been going
around for a long, long time.
And while in principle
it can radiate away
its emotional energy,
not by charge,
which has nothing of
but by mass which it
has by gravitational radiation.
To do so, takes something like
10 to the 25 years, a time so
long that we can leave it
out of all considerations
of our present time.
Because gravitational
force is so weak
that the radiation they
enforce for moving matter
is so small that it's entirely
negligible as long as you
deal with simple circumstances,
like the one I'm talking about.
Now the second proposal is the
rock of the earth, of course,
and of the terrestrial
planets and here
I've written down as
an astronomical sign,
rock broken into
small bits which
is what we call dust and
dust which is rock dust.
I shan't describe whether
it's silica, what it is.
It's some element, not hydrogen,
and it has many possibilities.
Now I think a
slightly worthwhile,
the one that I
cut off, just look
at that quickly,
this wonderful star
field in the
southern hemisphere,
a beautiful photograph
from the Australians,
is blurred by this object
here and in the old days
it was possible still
to believe absent much
mature consideration and lots
of statistics, that you were
looking here as Herschel himself
wrote about a similar object,
at a hole in heaven.
[INAUDIBLE] The stars
get out of the way
and show you a beautiful tunnel
out into depths of space.
Of course, that's
not at all true,
if you think about
the statistics of it
you will see it's very unlikely,
so many dark fingers are
pointing at us, he
saw just one maybe,
but if you see
hundreds of them, then
you have to have very
bad ideas of reference
to think that heaven is making
all these dark fingers pointing
at us or else a
very bad conscience.
I don't know.
Any case, we know
that's not by looking
at the light coming through and
by looking at many other ways.
We this is just a dust
bank which gets in the way
and behind it, that wonderful
field of stars is blanked out,
and all you see is the stars
that are in front of the dust
bank and that's only
rather few because it's
rather close to us.
So dusty is an important and
obvious consideration, now
you would say obvious.
But in 1930s, it was
not so clear but now we
have unmistakable evidence
for it in many different ways,
and we know that
it's really there.
So we have hydrogen and
then a little bit of dust.
I wanted to mention
it because you'll
see it over and over again is
just the same completeness.
And the third thing,
which is very interesting,
is a construct which you won't
find in the laboratory at all
because I call it star fluid.
So the third element that I want
to talk about is star fluid.
Now what is star fluid?
Star fluid is obviously
kind of a metaphorical name
for something you see
from a big distance
and don't see very
well, because star fluid
is a fluid whose
atoms and particles
are stellar and not atomic.
That's the way it looks you
see a picture of a galaxy.
Let's look at a
picture of the galaxy.
There you see a beautiful
sphere of star fluid,
now we know by sampling there
are a billion such objects,
we know tens of thousands of
them with some degree of detail
by actually having
studied them individually.
And they represent something
like the Milky Way.
Here's a couple little
outliers, that's
a nice big spherical, one the
same one I showed last time.
And the next slide, a more
familiar one, a spiral galaxy
instead of a globular galaxy.
I chose this one to show
both kinds are present.
And again you see right away
the same theme, a sphere
and a disk.
In this case the
disk, which happens
to have a small sphere
inside it, that's all right.
Combination, not too bad.
And again, the
same situation, we
must have random forces
opposing gravitational pull
on the symmetrical situation.
We must have somehow,
a system that
has lost an [INAUDIBLE],,
that has tried to keep it's
[INAUDIBLE] and lost energy
and has made a disk and the two
symmetries the disk and the
sphere correspond to everything
galaxies are either
spheres or disks or both.
Just as the solar system
is a sphere, a star,
many little spheres
running around
and they're organized in a disk.
It all looks so simple that it
gets almost a little familiar.
I want to show something else to
show, it's not quite as quick.
That was a bit fast.
Can you come back to
the previous picture?
I'd like to talk
about it for a moment.
There it is again, now
this looks very bland
but one reason it's bland
is because the instruments
in which everything
depends, there's
no way to get knowledge
except to the instruments.
Every instrument makes
illusions and the expert who
handles it knows the illusions
but when you look at it
hastily you might miss it.
Many theorist miss
it for a long time.
There's been a long time getting
this lovely outside tracery
just right.
By long exposures to bring
out this faint stuff,
way on the outside, with all
that interesting intricate
material.
But when you do that,
you burn out the middle.
It's flat bland.
Now a little spot, not as big as
the red light that I put there,
the laser spot right
in the very middle
is shown in the next slide.
A very short exposure,
and there it is.
That's the bright nucleus,
the Andromeda Galaxy.
Now, there's nothing
particular about it,
we I take a long exposure, we
get a bigger thing and longer.
What I want to point
out is the stars
are heaped up toward
the center of the galaxy
with a remarkable rate
of rise, so the density
of stars and of star
light from the center
is three or four
orders of magnitude
greater than the
stars pile together
in the same small
volume outside.
The volume which this
occurs is very small,
so the total computational light
of the object is not large,
but compared per unit volume
it is 10,000 times more dense.
The absence of dynamic range,
the ability to get [INAUDIBLE]
and crescendo in the same
passage, that most instruments
lack that.
I'll show you some
later that don't lack it
and you'll see wonderful things
that lots of dynamic range
brings you, because you can't
always neglect faint things.
Small things may be
quite significant.
In this case, the small,
the high intensity of that
is quite significant for us.
The next slide is
just to show you
these things are
not always separate.
Here I have a picture of the
coma cluster, the certain point
in space, rather far
away from us a couple
of million light years.
You see there is a sort
of an ellipsoidal galaxy
and a few more.
And then there's
[INAUDIBLE] spiral and there
a nice spherical looking
one and some funny ones.
Bunches of galaxies
in the single picture.
You can count a
couple of hundred
in that cluster with
no trouble at all.
So these things do
occur, they cluster,
the galaxies are present.
This is all the classical
material of the astronomy texts
some time ago.
I would like to add that
you see this the stuff
that I'm talking about, I
should give a name to that.
I observe it as a homogeneous
material in these pictures,
that is the only way to
see it but it's star stuff,
it's fluids.
It's a fluid made
of stars, its form
is what is most conspicuous
in this kind of picture.
I came with a spectrograph,
examined the light in detail,
and I can map it and see
how the density changes
and so on as I've shown you.
So we do have a little
more information.
But primarily we're
studying star fluid.
It's perfectly good to
call it that because that
was made of individual
stars, and those stars
are not touching each other.
We see them as though
they fill all space.
That's because the instrument is
not capable of separating them.
Instrument, including
the atmosphere,
is not capable separating them.
They run together
and you get a glow,
the glow is actually
the sun-light
of 10 or 100 billion stars.
No one of which is close to
the other and no one of which
practically hides
the other either,
they're so far apart by
comparison their own size.
Like the stars in
our neighborhood.
But you see the merge together
in the instrument just
makes a star fluid of it.
So it is a star fluid and
it's worthwhile mentioning it.
It's quite important.
So I will say the star fluid
is there, fluid moves about.
It is what heaps up into a
sphere in the spherical galaxy
and is flattened out into
a disk in the disk galaxy,
and maybe a sphere
in the middle.
It is lossless--
the stars haven't
got any way of getting rid
of their motional energy.
Of course, individual stars
can get cooler or warmer--
whatever they're doing on
their own individually,
and I observe that that
belongs to stellar [INAUDIBLE],,
not really described.
Very interesting and almost
mature between 1920 and 1970.
Roughly speaking, that was the
time which we understood most--
not everything-- most
of what stars do.
So this lossless fluid, it's
lossless in its motions.
It has no way-- it doesn't
collide, it doesn't bump into--
do those stars bump
into each other?
They don't.
The friction they have
from the residual gas which
might be present is very small.
How can you stop a star with
just the friction of gas?
You can't do it.
And so it is a kind
of perpetual flow
of fluid-- a very nice
thing to study [INAUDIBLE]..
Of course, don't
forget two things.
First, it's interactive.
Though it is lossless,
it is by no means inert
because it is attracted--
attracts gravitationally
with great vigor.
We're talking about
little parcels of fluid
floating about-- each one
has 10 million stars in it.
It's not a small concept--
there's lots of energy
there, lots of
gravitational attraction.
But of course, it can
evaporate, it can dissipate.
And if it's thrown out into
space and made very dilute,
we don't see it because we can't
see just a tiny bit of light
against the background
of everything else.
So you have to have it less
than dilute in order to see it.
So that's the third material.
But now in terms of that
material and the two things
I've described, namely the
hydrogen dust and star fluid,
we have a description of all
that we can see in galaxies
and the solar system.
Solar system is the prototype.
And then in the galaxies
world, which I'm talking about,
the galaxy does the same thing.
Disks, and spheres,
and their combinations,
clearly a balance of energy
and angular momentum--
the great constants
of mechanics.
The star fluid flowing
about and adjusting
itself to fight the gravitation
either with spherical random
motions or with well
oriented, circular motions,
or quasi-circular motions.
And of course, there are
lots of small differences,
there the famous
density waves that
make the spirals of
professor Lin and so on.
But these are, from this
broad brush portrait, details.
Very interesting and significant
for origins perhaps, but not
determining the broad picture.
I haven't had to show
you pictures of those
which was very conspicuous.
So I can say that the solar
system and the galaxies
ruled by gravitation,
as we admit,
made of hydrogen. Of course,
the hydrogen makes up
the stars too, but we're
not talking about the stars
except as parts of the fluid.
And a little dust thrown
around to make the earth
and the dust of space.
Solar system and the
galaxies ruled by gravitation
seem as tranquil as the almanac.
The rounds of the heavens,
while quite interesting,
and the gyrations are fun
for us to watch and study,
and we can time ourselves,
and navigate and do
wonderful things, it
is really the almanac.
You look it up and there
is just what it will be.
It's already out
for 1989 I believe,
and it's going to be right.
You won't find any errors.
[LAUGHING]
And that's about
all you can-- that's
the only part of the subject
which has that quality,
I can assure you.
And of course, that
quality enormously
misled us until we got better
instrumentation and better
understanding.
This is home.
Home is where the
hearth or heart is,
and home is where you
get your wrong ideas.
[LAUGHING]
Okay, so now we'll
talk about what
20 years has brought, mostly
because you have the ability
to look rather far away.
Because if-- you may well
believe home is where
the hearth is--
it's not a coincidence, yes?
Here I must invoke the fact
that if it were not that way,
it's very hard to make a living.
You can only work
when the sun rises
every day, or at least on
weekdays and things like that.
So you've got to have
a general regularity.
Are the irregularities,
disorder, chaos,
lack of equilibrium, lack
of clear temperatures, disks
and spheres--
are those things
the solar system?
You bet they are.
Cosmic rays, aurora borealis,
comets, meteorites, asteroids,
but you've got to be an
expert to know about them.
Well, perhaps you can see
a comet from time to time.
And the ancients
were right to feel
the comet was a sign that
things are going wrong,
because the comet--
I have only to point
out one remark--
comets, of course,
are not very bright,
but comets are not in
the ecliptic plane.
In fact, they're uniformly
distributed in direction.
So how come?
We have a good argument.
Well, it shows the
details, if pursued,
will lead you're far away.
And so we didn't-- we
weren't wholly deceived.
But broadly speaking,
we had the illusion
that gravitation is a
delicate subject which
works on fine details.
And you can get-- yes,
the procession of mercury
was a little ahead,
and so Einstein could
make a great thing of that.
That's the kind of style
it was, and so that's
the way we did the
thing for a long time.
But that was once, and
it's not any longer.
Now, I say, we come
to the fireworks.
It turns out that this
entire picture is based
on experience, common sense--
the common sense
of the scientists
engaged in galactic and
planetary observations--
but it's wrong.
I should not say it's wrong--
it's not a blunder.
It's incomplete.
And that's of course
generally what we have.
We have well-founded theories,
well-founded descriptions that
don't cover all circumstances.
They cover our
circumstances at the time,
and that's why they fit.
And when you press
the limits, you
find something new happening.
So I come to--
and it'll turn out that
I get to introduce,
we got only one
more new substance.
It isn't substance that's
novel, it's motion and form,
and we'll come to
that as it goes on.
In the first place, I think we
should look at a slide or two.
If galaxies cluster,
they come close together.
When galaxies come
close together,
they sometimes
approach each other
and confront each other
in this interesting way.
This is a square dancing
pair of galaxies.
And it bear's tails--
I mean, gosh.
[LAUGHING]
That doesn't look
like anything you ever
saw in the typical
book of some years ago.
It was there all the
time, but it was only 100
out of 10,000, so who's going to
bother pick up such an anomaly?
And now we understand
a little better.
And the second picture--
this one is called the
antennae for obvious reasons.
And here, the galaxies
are flinging something
over each other's
shoulder in a strange way.
This has been
beautifully modeled
by [INAUDIBLE] here
for the past 15 years
or so in simulated effect.
And there's no question
of what we're seeing,
and I would describe it
in the following language.
You know by direct
observation that the motion
in those twigs, those
branches that come out,
is not an anomalous
or strange motion.
It is a motion
rather like the rest,
but the form is very strange.
What has happened is
that the tidal flow
has drawn out star fluid, which
also can recoil gravitationally
just as the tidal bulge
recoils from the moon--
if you know there are two bulges
of the tides on the earth.
And drags with the gas, and if
galaxies will collide with each
other-- that has come
near each other--
then this beautifully
stabilized sphere disk fluid
that we talked about,
which has no losses
and responds beautifully
to any pull upon it,
gives up its allegiance
to that beautiful order,
which was all historical.
No longer has zero
angular momentum.
It has zero angular
perhaps, or it
has the right kind of
angular momentum with respect
to its own center, but now a
conflicting center has entered.
What to do?
It has now a lot of
angular momentum in respect
to that one.
It makes some kind of a
balance, and a complicated thing
ensues which I shan't describe,
but has been worked out
in beautiful detail by computer
simulation and, to some extent,
by analysis.
And in these collisions, we
are quite clear that the star
fluid is drawn out.
Its just stars with
accompanying gas--
nothing bizarre-- but drawn
out into tails, and even
rings and mergers.
And the next slides will show
you what some of these things
might look like.
This is in the sky--
this is not something
in the computer.
It's a bad photograph of
a rather remote galaxy,
but it's a funny one.
It's a blobby ring.
I mean, looks like some--
I suppose some piece of pressed
pasta you might get like that--
like alphabet soup.
Well, look at the
next slide which
is a computer simulation of
[INAUDIBLE] and coworkers.
[INAUDIBLE] this one.
Suppose you have
a model galaxy--
just stars moving around
in nice, circular rings
around an axis, and I
fling through that axis
right down there.
And another galaxy--
small but rather massive--
similar in mass to
this whole disk--
and watch what it does.
It induces a beautiful
central ring,
and if you put it obliquely,
it induces an off-center ring
matching the one we have.
And it does so in a rather
straightforward way just
by gravitational forces.
Gravitational forces
draw the particles in,
and then as it goes away,
they come out again.
And in all this
do-si-doing, they
run for a while in
the same positions.
It turns out that
their positions
cross each other as they're
trying to get in and out.
And therefore, transiently,
during this event,
they make a ring which will
dissolve a rather short time
on a galactic scale.
A time small compared to
the time for the galaxy
to turn around once--
maybe a half or a
third of that time.
So you see right
away-- and now we
have maybe 50 or 100 these
objects of all these kinds.
The next kind-- we'll
show another one.
Here's a galaxy-- it's a very
normal looking elliptical
galaxy--
it's a flat galaxy
at s0 so-called.
It doesn't have any
spiral arms or gas in it,
but it's a rotating disk, and
the spectral end showing you
its rotation.
And then lo and behold, it
has a ring the other way.
I mean, that's not
self-respecting.
[LAUGHING]
When I was brought up to
learn the subject very badly--
I never took a
course in astronomy--
I would have thought
it outlandish
that I have a thing
like a solar system,
but then instead of the
solar system with everything
in the ecliptic plane.
And then even I
could imagine there's
a sphere of comets that
flies in from all directions.
But to have a ring
going through the pole
and around belongs in a library,
it doesn't belong in the sky.
I mean, it's the ring that holds
the globe of the Earth, right?
[LAUGHING]
Well, I mean, there you have it.
And it's real, and it's
made of bright stars,
and it's not moving
especially rapidly-- it's
moving just the way it has to
move to be in that condition.
It's highly transient.
As you may well imagine, it will
spin around in its own plane
and gradually work its way
until it's merged into the disk,
very likely in the
course of some time.
But transiently, we see them.
So there's a lot of fireworks
of this strange motional form
kind found in the galaxies.
Here's another picture in which
people overexposed heavily.
You lose the ring, but you
bring out all this gas--
all these stars
which have come out
of a gas that's
been made somehow.
Everyone believes--
I think it is right--
that the collisions occurred
in the past and some galaxies
have merged, and
the consequences
to fill up this polar region
with some gas in which some
stars condensed.
And now we see this object for a
while in this bedecked fashion.
Galaxies, in short, do
not have single origins.
They are what the biologists
call polyphyletic--
they have more than one
ancestor very often.
And of course, untangling
their origins--
we're ignorant of that--
is going to give you
a very hard time.
Maybe simple galaxies
[INAUDIBLE] good,
we'll look for those.
But that's not all
there is, and so don't
be worried about anomalies.
The world is various
and this what we see.
So [INAUDIBLE] conflict--
you get tails and rings.
I think I should have
the other one too--
sorry.
There's one more bad slide,
but worth looking at.
This is a galaxy and
it's got the measles.
It's all one galaxy
but it seems to have
many central hot spots--
central nuclei.
And the general view
is we're looking here
at a cannibal galaxy--
some Saturn, Cronus who
has eaten his own children,
and there they
are, half-digested
in the stomach of the beast,
whizzing around in there.
I don't know if this
interpretation is fully
verified-- it looks pretty good.
And there's no question that is
happening-- the galaxies merge.
You'll say how can it
be, if it's lossless,
that you can get caught?
Well, you see how
it can be very well.
It's not that that the energy
is lost to the star system.
No, no, it remains but
has given some energy
to stars that have flown
away, and therefore
taken some energy from
stars that remain behind,
and they're orbiting around
while the rest are sprayed out
into space.
Overall, energy is not lost.
There is no collision in
the sense that there's not
much radiation,
excitement, [INAUDIBLE],,
nothing of that sort.
Just and removing of the
star fluid because star fluid
has only those properties.
It's quite a remarkable
result. And it describes--
it gives us an
account of about--
oh, a large fraction of all
the galaxies were published,
say, many years ago, in a
wonderful iconoclastic paper--
a booklet by Chip Arp which
he called Peculiar Galaxies.
He's a specialist in
mustering anomalies.
He mustered up all of
the anomalous galaxies
he could take pictures of, and
a good half of his galaxies
perhaps belong to
this collisional stuff
where star fluid was worked
into funny shapes just because
of collisions and the
aftermath of collisions
always under
gravitational force.
Now I want say a
little about scale
because that enables me
to make the next jump.
Scale tells us this-- this is
the next kind of fireworks.
A kilowatt hour--
everybody knows, a kilowatt
for an hour, 1 kilowatt hour.
A sun life is another--
the sun power for
one solar lifetime--
not our lifetime,
solar lifetime.
That's another unit of energy
just like the kilowatt hour--
the sun life.
It's a lot of energy.
It's the kind of energy that's
given out in one supernova
all at once in a
few months time.
It's about 10 to the
10th solar years,
and this is the scale
of what stars can do--
it's about all stars can do.
Now a lot of events
that we see in--
what we saw here, there
might be bright stars
and supernova-- nothing much.
Just star for star
giving out it's
its sun life power
would be plenty
to account for all the things
we see in these relatively
tame but badly disturbed forms.
But that's not all we see.
The next thing we see is
shown in the next slide.
Two very nice
galaxies rather nearby
in the constellation Ursa
Major in that direction--
known to everybody as m81, m82.
I'd like to point out
this shy one here is
another one it's called 3077.
It's not my fault
the photographer
didn't adjust the field
very well to get that.
But there are three there,
and there's even a fourth one
down off this corner.
Just very unpleasant the way
the photographs were taken.
The next slide will show you
something a little different.
Now this is the same
field in the sky--
it's a map you recognize--
no longer a photograph.
And I've drawn the
plus for this--
the plus side is
the galaxy itself.
That's m81-- that beautiful
big one that was in the center.
This is m82 that went
up there in the corner.
This is the one who
was shyly over the edge
and this is the one
you didn't see at all--
it's on the edge
even in this picture.
Now what is this map?
This map is a wonderful map
made by the radio astronomers.
Of course, it is only
because we have the power
to look in so many
wave bands that we
can make this kind of study.
And this is an old picture--
a decade old or more--
in which somebody has
made the radio frequency
signature of this same object.
And I have marked
with a plus sign
where the galaxy centers are.
And the optical galaxies
are not much bigger
than those plus signs--
a couple of times
bigger for the bigger
one, and so on.
And you see that there is
a whole mess around there,
and we know from the nature
of the spectral line which was
taken that that is neutral
hydrogen gas-- atomic hydrogen.
A giant cloud of
atomic hydrogen--
whose motions we can see, but
they're very complicated--
surrounds these
four galaxies that
are immersed in that cloud.
Now there's quite a
general phenomenon--
we see that very
often around galaxies,
but we don't see multiple
galaxies immersed
in a single cloud very often.
These galaxies have
been in interaction.
They have flung
out hydrogen gas,
it is flowing about in
there and a completely--
what was an invisible
part of the universe
is now clearly an important
part of the history.
It is not dynamically
important-- that's to say,
the mass of the gas is
small compared to the mass
of all those galaxies.
Not enormously small, but of the
order 1% or a part in 1,000--
something like that.
So it's not making
the galaxies move.
Rather, the galaxies
are making the gas move,
so that seems all right.
But notice what
happened to m82--
which is one that I spent quite
a few years worrying about,
which is this fellow up there.
Let's look at the next picture.
There it is colorfully
displayed in the usual color
enhanced photograph.
Notice it's a very--
it's not a galaxy that you
would put in the textbook
to illustrate spirals.
It is a sphericular
disk rotating
the usual way seen rather
edgewise-- so you'll
see there's a long spindle.
You'll notice
spiralism is gone, it's
full of these dusty
clouds, you can't make out
any individual stars in it much.
All of that's entirely
consistent with all
the infrared and
everything else you do.
You see it on the infrared,
X-rays, radio, all these work.
Let me show you a
few more pictures.
Same object here-- is the
same picture as before without
the color--
optical.
Here it is looking [INAUDIBLE]
color of light, just
the hydrogen alpha line.
Neutral hydrogen is being
flung out rather faintly
from the two poles.
Here's the polarized
light coming
from a big surround
of the whole thing,
and more polarized light
in different polarization
direction also way out on
the outside of that spindle.
We have very little doubt that
this is a very dusty galaxy.
Dust is filling
the whole region,
and the dust is
concentrated towards m82,
and that dust is giving
rise to polarized light that
is seen here.
I needn't describe why that is--
that just as a useful phenomenon
for people to look at.
Now let's look inside the
galaxy a little more closely.
Here is a radio
picture of the inside.
This is the inner 10th--
beautiful colored contour map.
And look at that fine, bright,
large, red burning source
there.
That's the biggest
source in m82.
This is a slide
due to [INAUDIBLE]..
And since then--
not yet published,
but in the last few months--
Professor [INAUDIBLE] worked
on this object for many years--
has made really excellent high
resolution study at the VLA.
And he would now, if I had
brought his map--which it was
too complicated to
bring in I think--
this same region contains four
dozen other sources like that.
Of course, all about
five or 10 times fainter.
They don't show up
in this picture--
not enough dynamic range.
But little point sources
filling up the whole region.
So the notion that
maybe this thing
was a hot nucleus of the
galaxy-- you see the suggestion
Andromeda had a nucleus which
is just a collection of stars.
But other galaxies we'll see
have nuclei there where much
activity is going on.
And here's a galaxy that
is bright in X-rays,
and IR, and everything else
in the center, and radio.
But when we looked
at it in detail,
it was not from the center, it
was not from a single source.
It was spread around
throughout this region.
And so if-- I have called--
I think it's the galaxy
which was falsely active.
And when you look
in more detail,
you see that's the case.
Here's what the core looks
like if I map it, actually,
with a pen next to--
this is the way that m82
looks with various objects
that people have seen.
IR sources, and radio sources,
and bright clusters of
stars and so on.
Through the dust,
very hard to see.
Here's our galaxy
core-- the same region.
This is about eight times
as big as our galaxy,
but it's only 1/10 of m82, which
is smaller than our own galaxy,
but very much larger than the
little point in the middle,
and that's the thing
I'm talking about.
Here's what our
galaxy would look
like if it were enlarged
to the same scale--
just enlarge it.
And now you see it
too has this kind
of miscellaneous junky things--
radio, and X-ray, and IR,
and all sorts of
wonderful things.
There is very little doubt
that the m82, in all its glory,
is an object which has not got
a single active center inside,
but has instead a
collection of stars.
A very rich, abundant collection
of newly formed stars,
giving out X-rays, and
IR, and making explosions
which give radio sources.
Doing all the things
that supernovae do
and other disturbed stars.
And that is indeed what it
is-- it is a starburst galaxy.
In this galaxy within the last
few hundred million years,
there was started in its center
a generation, an abundant rash
of stars, all born
more or less together,
and still being
born out of the gas
and rushing around inside there.
So it's a kind of activity, but
no single part of that activity
is more than the one sun
life, or 10 sun life kind
of thing I'm talking about.
It is not any great single
center that is doing it.
It is a burst of stars.
Very exciting and very
interesting, but in a way,
not really on a galactic scale.
And there was little
doubt that what
did it was that the
star fluid that appeared
brought gas with it, and the
gas from that radio cloud
that we saw fell
into the center--
having been expelled
from its own galaxy
and no longer with any
great allegiance in terms
of angular momentum with
respect to that new center--
fell in, and stars condensed
from that material.
A truly remarkable event
which is a possibility--
that gas can condense in
starbursts and form stars.
Of course, it is gas
that must form stars.
And stars that
give rise to gas--
and this transaction we've known
in our own galaxy for quite
some time, and now we see it as
an epidemic in other galaxies.
But that still is not the
story of the fireworks
that we really want to
tell, because these are all
mild fireworks.
Let's instead go on to the still
more grandiose kinds of events.
Here's that same m87
galaxy but underexposed,
so you don't see as big a sphere
as you did before in color,
which makes it look nice.
And notice this funny
thing sticking out
like the tip of a
hand of a clock.
Let's look at the next picture.
Underexposed still more and
a complete hand of a clock.
Let's look at the next picture.
Underexposed-- here it is
again with a little tip.
Here it is with a
hand coming out,
and here it is
with the so little
exposed that only the
bright central core is there
and this tip of
the hand is there.
Now we know a great deal
more about this now,
but suffice it to say that this
is an objective of big size.
Subgalactic because
it was inside m87.
You didn't see it if you
burned out the center.
If you look at the
center, you'll see it,
but it's not at the center.
Again it's a-- but it is a jet.
It is a linear
structure coming out.
And we see now quite a few of--
nothing quite like this, but
quite a few related objects.
And I think I would
have to say that this
is a quite characteristic
thing to look for.
And above all, the scale
is what is important.
The scale, by which I mean
energy scale, of such objects
pushes 10 to the 8th, 10 to the
10th, 10 to the 12th sun lifes.
The X-rays, gamma rays, perhaps
cosmic rays, other high energy
phenomena occur there,
and this is what
makes it quite interesting.
Now the next few slides will
show the domain of the quasars.
I call these-- these are
the kindred of the quasars.
Here is the most famous one of
the brightest nearby quasars--
only 3,000 million
light years away.
And there it is
heavily overexposed--
it's really just a tiny spot--
a speck.
But the telescope
brings it out looking
as big as the stars, which
of course are also just
spots spread by the quivery
motion of the atmosphere.
But notice this jet.
Now that jet is, we now
have reason to believe,
100 times bigger than the
jet of m87 in real life.
It's quite a remarkable thing.
Two pictures of it in
two different colors.
Let's look at it
again in the radio.
There's the little-- a nice
radio source around the center
quasar itself.
And here's this wonderful
hand of a clock--
a fair-- about 100 times larger.
And now all this--
the optical jet
is right in here.
This is not-- this goes
well beyond the optical jet.
What is that map showing?
That map is showing the
presence of radio emission--
a large amount of it.
The size of it is bigger
than 100 galaxies.
You don't see it at
all on the radio.
It is a region of space
filled, we now believe,
with relativistic particles--
I'm going to call it
high energy plasma.
We see hundreds of examples,
thousands of examples.
So we really believe it's
the next constituent.
I know that it must be something
strange because it's energy
scale is enormous compared
to that of any star.
It's a galactic dimensions,
or greater than galactic
dimensions.
It doesn't give any visible
light at all, or very little.
It gives polarized radio,
and the best explanation
is that it is interaction
between ionized hydrogen
plasma-- relativistic
energies-- and magnetic fields.
So [INAUDIBLE] a novel
substance, high energy plasma
and b fields.
The velocity of electrons is of
the order of velocity of light.
I remind you the velocity
of an electron in an atom
is 1% of the velocity of light.
So this is really far beyond
anything that atoms can dig up.
It is a much more, as we
say, relativistic energy.
Now center of this object
is worth looking at too,
and here's a remarkable
picture of it.
There it is.
The plus shows where the
center of that galaxy would be,
which you can see.
This is in fact a magnification.
This is a galaxy--
this orange stuff.
And this is the
direction of that jet.
This is taken in visible
light, but enormously, heavily
doctored, so it's not
a photograph at all,
but a map elaborately
treated by a computer
to bring out this fine detail.
So we are pretty sure that
the quasar is a brilliant spot
100 or 1,000 times
brighter than a galaxy
living inside a galaxy,
capable of throwing out
a jet like the one
we saw in this case.
And the jet at the
end makes a grand pool
of relativistic plasma
or high energy plasmas,
as I've called it, out in space.
A truly remarkable
explosive event.
----[INAUDIBLE] a
great distance apart,
timing them by our
absolute clock,
have been able to resolve
1,000 times better than
the resolution of an
optical telescope.
So we're looking
at a magnification
deep, deep in the heart
of the object, far smaller
than anything I've shown in
any of the pictures before.
And when you look at
that magnification,
you see two clouds--
this permanent cloud
and this moving one.
And that's been done
now in a dozen objects,
all the same kind--
these brilliant quasars,
or radio galaxies,
surrounded by great pools
of relativistic plasma.
And the conclusion
is hard to avoid--
that you're seeing the
separation of that inner cloud
from the central cloud
moving with a speed,
as you see written there,
10 times the speed of light.
This is the so-called
superluminal expansion
of cores of radio galaxies.
Now we know that no physical
object is moving faster
than the speed of light.
We would be very
surprised-- it would
take powerful evidence indeed
to disabuse us of that view.
So we have been
able to figure out
that it is, of course, an
interesting illusion which
I shan't really describe.
It depends on the
fact that you're
looking at something that is
approaching you very rapidly.
And so the correction
for the time
that it takes the
light to get here
must be taken into account.
It's moving nearly as
fast as light toward you,
so that makes a big difference.
The element is not
moving toward you,
and that makes a difference.
And if you correct for that, it
turns out the relativity indeed
predicts exactly that effect.
Objects moving toward
you will appear
to be moving in their small
way across the line of sight--
the little angle not
exactly towards you--
a little bit to one side.
They'll appear to
move in that direction
very rapidly indeed
because you don't see them
with the right time delay.
Every part that
you're looking at
comes to you at
a different time.
So the time sequence
has to be recalculated
and when you do that, it comes
down to the speed of light.
So there's no mystery about it,
but a grandeur which we really
had not understood.
This is a powerful object
and it is certainly puzzling
what goes on in
the center of it.
And now the--
I think that's enough
for that slide.
We know that there must be
a central engine inside such
a quasar of high efficiency.
We know that because the
mass that it contains
is not very great--
it's not enough to dominate
the motions of the galaxy.
So we give a limit to the mass.
At the same time,
we see the energy
that comes out of it filling up
these great clouds and pools.
Invisible galaxies
in space-- super
galaxies which are not
made of stars at all,
but of high energy plasma.
A completely new world--
nothing really like the world
comparable in our solar system.
Only a little bit to
flares on the sun.
But now we see them,
gigantic and enduring.
Energy much larger
than the rest mass
of electrons-- the electrons
present and a subgalaxy mass
is doing it.
Indeed, the size
of the whole thing
is smaller probably
than a light-day.
We know that from
direct measures
which gives some limits, and
better from time variations
which show that the whole
thing is so small that you
can have some time variations
inside of a light day.
Now we're mostly talking
about 10,000 light years
is a characteristic size unit.
So it's a tiny
needle point speck.
Even the magnified
picture I showed you
was 5 or 10 light years across.
Now you must go inside that by
another 100,000 magnifications,
and you'll see the central edge.
And of course, what
you don't see--
we can only infer it--
and we have a lot
of ideas but nothing
very firm about what it makes.
I want to show the
best of the ideas
and then close with
this very soon.
So the next slide, please.
Here is a wonderful slide that
makes the point extremely well.
Here is a radio galaxy--
again, a computer
maps it in the radio.
A big puff there, a big puff
there, and a central galaxy
that puts the puff
out both directions--
not just one direction like
273, but as you'll see more
typically in both directions.
Enough time has elapsed for both
sides to be treated that way.
Now this [INAUDIBLE]
was magnified,
and a long, long line is shown.
But this magnification
is from one mega parsec
to 100 kiloparsecs,
so this is a factor
of about 20 magnification.
And if we magnify once again,
this is only one parsec--
that's a factor of 100,000.
And again, you see
this flame like thing--
we lose all detail now-- we
just barely get something.
But notice, this line,
this line, and this line
between the two great
clouds which are 5 million,
3 million light
years apart, and this
is only 3 light years long.
Over a scale of a million, this
object has moved in such a way
that along one
direction in space,
it's always had the
same orientation.
It took, of course, several
million years to produce.
So for several million
years, an object
has been put
pointing out material
along one axis in space
without ever deviating.
Now that stability
is inertial guidance.
That has to be a gyroscope--
there's very little other
way to make it so firm.
And so again we're
confirming the notion,
the central edge is not only
a powerful, compact object
of subgalactic mass
and solar system size,
but also it is heavily spinning.
And the only thing I wish
to draw from this is, one,
I don't want to say what
the whole structure is.
But the kinetic energy of
rotation for a solid object
is, of course, the
[INAUDIBLE] divided
by the moment of
inertia, mr squared.
Now this goes up like r squared,
but the kinetic energy only
goes like the
gravitational energy-- that
was the Virial theorem
I quoted-- k like v,
but v goes like 1 over r.
So while k goes up, as
something contracts.
The k rotation, which
shouldn't have rotation,
goes up even faster.
And so eventually,
it will catch up
and take the lion's share
of the kinetic energy
and make what I think we
have to call a whirlpool.
And that indeed is the
last kind of fireworks--
it's the most powerful,
the most extraordinary.
We now know of some
thousands of these objects--
some well-studied, some only
with one hint to their nature.
And they are pretty surely,
all of them, massive whirlpools
of spinning, magnetized material
whose center is generally held
to be a black hole, not in
itself demonstrated yet.
But we must find some
mechanism for that to work,
and this is rather plausible.
They are concealed by their size
and by radiation and particle
interaction.
They're so dense with energy
in a well-defined case.
They're so full of radiation
that the particles on the way
out and the photons
on the way out
mutually interact with
each other in a strong way
as well as any magnetic
fields that are present,
and conceal in this
multiple interaction
the details of the
structure that are present.
This is the center
of the whirlpool.
And of course,
the other thing is
that out of one end or
the other, or both--
I tend to believe it doesn't
come out at the same time
out of both, but tends to
favor one and then the other,
but no one knows that for sure--
a fountain or jet.
And a new constant of motion
has entered along the axis--
axial momentum, p.
The same momentum as flinging
a ball out into space,
only you do it repeatedly--
many balls, or many particles,
or many something-- a
flow out into space,
which is the jet or fountain
of these great galaxies.
I wish I could tell you
what the substance was
that's going out there--
I don't know.
I'll say a little bit
about it, but first
to show you two
pictures which both come
from work done at the
VLA by my colleague,
professor Dreher-- he's just
10 feet in front of me there.
And here is his beautiful
picture with high resolution
and wonderful dynamic
range showing weak features
that no one ever saw
before and discriminating.
And these pools that
we talked about,
which are so nice to
call pools, well, they're
not static pools--
homogeneous objects-- at all the
way they were drawn on the red
map that you saw.
They're full of
intricate tracery--
heaven knows why.
And there it is again.
And who knows, if
we magnified it
once more with good dynamic
range, if we would not see
helical threads develop along--
I don't know.
I just don't know.
Let me show you the next one
which is even more striking.
Here's another radio galaxy.
Again, seeing the same
high dynamic range scheme.
And this one is
throwing out a beam
which is itself generating
pretty surely puffs
of some kind--
puffs or relativistic particles
capable of making radio.
There's one, there's a bigger
mixed one, there's one.
Here's the very
clear one at the end,
and look at this great
big one out there.
Now what's going on?
It's not easy to make a
model for this-- there are
many tantalizing possibilities.
Some people see
in it a sort of--
like real skyrockets.
An object has been flung out
there which itself explodes,
or many of them which
explode one after another,
and give you these puffs.
Maybe it is some kind
of internal collisions
can be made.
I'm not prepared to go through
the time and position sequence
to suggest which it is.
Suffice it to say, nothing
is very continuous.
What we know, this
really remains
a somewhat mysterious, but
hard to argue away, picture.
And all we can say is we
don't know very much what
is the fountain-- the jet.
That's what I wanted
to end, by saying,
yes, it is hard to know
what's going on there.
The substance of the very
jet itself is in doubt.
I like to think it is
sometimes hydrogen plasma--
negative electrons
and positive protons.
Sometimes, perhaps mixed
together electron and positron
pair plasma.
I think we've never seen
before, except in the occasional
particle accelerator
on the earth,
but capable of being made in
these great central engines--
the whirlpool in the center--
where radiation
and particles are
in strong relativistic
interaction.
We don't know-- we
have to find that out.
And maybe it throws
up those bombs
that are making
themselves explosions.
I hate to believe that,
but it's been suggested.
We had a fling at it
ourselves years ago.
I don't think it's real,
but we don't know yet.
All we say is we don't
know what the jets are.
I think that the theories
which exist, which abound,
are probably premature.
Of course, there are
very many of them.
I've only selected a few.
They differ.
They have broad
characteristics in common,
but many details differ, and
probably everybody's theory
will tend to have some
place of application.
That's the nature
of the subject--
it's not a simple subject.
A description of the way the
world works and not the way
you can abstract to a single
particle in the laboratory.
So I can close now,
and I will simply
say that I think
we've demonstrated
there are fireworks out there.
That the fireworks are
foreshadowed, but only
faintly foreshadowed, in the
comfortable domestic universe
that we once had.
I think we have demonstrated
pretty well in the last 20
years that two universes
are commingled--
a domestic one and an alien one.
We could not live in or near the
alien structures, but we don't.
We could, and indeed, do
live, and are adapted to,
and nurtured by the
spheres and the disks
of the uniform well-behaved
gravitation of the almanac.
It's the same
gravitation, but we
see it combed out
and tamed by history.
Indeed, when the
world was new, it
was heavily bombarded with
all kinds of chaotic bangs
as the moon's surface
still shows today--
at a time when the
solar system too
was a place of chaos
and randomness.
That we live among
order is the sign
that we have lived here,
not the demonstration
that order is everywhere.
Yes, order can come,
but it requires
an evolutionary
sequence to appear.
So that's it.
The domestic and the alien
both evolved, and of the past,
I talked a little bit
about that last time.
The cosmos of the past
was extremely bland,
but it had very high energy.
And that combination,
blandness and high energy,
gave rise to the complexity
and the disorder order combined
that we see by looking around.
But of course, until
you look far away,
you won't find
anything but that which
is suited to where you
are, and this perhaps
is one of the lessons.
I wish that theorists could
have said a great deal more
about this-- it would be nice.
Mostly, as I say,
trying to follow.
I think the challenge for the
next-- the rest of this century
is to try to put
this kind of subject
on a footing similar to
the 20 years that we spent,
or 30 years more, in getting
the theory of stellar evolution
into some kind of maturity.
That's certainly the challenge.
It is not there now.
We do not really
know what we claim
to have known about the
spheres and the disks.
We need much more.
We have a very interesting
challenge placed before us,
primarily experimental.
The ideas must come from the
theorists-- they will come.
The space telescope of '86 will
be an important contribution.
Many other things will come.
The wonderful improvement in
technology, of measurement,
instrumentation that clever
physicists are inventing
every year is, of
course, the clue
to understanding the universe.
So I close then with a
reminder that back we
are in a tranquil world.
There it is.
And of course, this is the
dome of the observatory,
and this is where
we think we are in,
but we're only in
a portion of it.
I am also mindful--
just to close-- that there is
a little contradiction here,
because I know in this
dome there might be a CCD,
and that CCD was not
developed by astronomers,
but in the service of infrared
monitoring from high orbit.
And I think that we will
manage to understand
this extraordinary and
challenging universe if we
can stay at peace long enough
so that the experimenters
and the theorists can work
out what is really there.
Thank you.
[APPLAUSE]
