>> Ofer Dekel: Okay let's get started. It's my pleasure today to introduce Nancy Abrams
and Joel R. Primack from the University of California in Santa Cruz who I've known for
over 30 years, so you can try to do the math about how old I was and I met them over 30
years ago. Nancy is a lawyer, a philosopher of science, an accomplished author, lecturer
at the University of California in Santa Cruz and also a musician. As a young boy I had
the opportunity to play around with the first synthesizer that I ever got to touch. Today it
would be called maybe a keyboard or electric piano in Nancy's house, and we would have
discussions or maybe arguments about whether synthesized music is music at all. I was
kind of a purist back then. I thought, I would say no, but Nancy was much more
progressive and saw the revolution of synthesized music. So I would like to take this
opportunity after 30 years, because I don't think we ever resolved that discussion, to
admit that I was wrong and 30 years of synthesized music proved me wrong. It is in fact
legitimate music and now I know to appreciate it in songs, so that is--we can settle that
argument.
And Joel is one of the leading cosmologists in the world. He is a distinguished professor
of physics at the University of California in Santa Cruz and a longtime fellow of the
American Physical Society. He played a seminal role in creating the standard model of
what is known as the standard model in particle physics as well as the theory of cold dark
matter which is basically the cornerstone of the modern theory of the foundation of
structure in the universe. And not only is Joel an accomplished physicist, but he is also
no stranger to computations so maybe things that would be more relevant to the audience
in this room. So in fact one of his areas of expertise is large-scale simulations of,
physical simulations on supercomputers and I think things that are actually quite similar
to things that we do here.
Nancy and Joel teach a popular and award-winning course entitled Cosmology in Culture
at University of California in Santa Cruz. In 2006 they published their first book which
was entitled The View from the Center of the Universe and this was a huge hit. This
book discusses a new way of understanding the universe and more specifically the role of
humanity in the universe. Following the publishing of their book they started a big tour
that gave many, many talks on this topic, and in 2009 they gave that Terry lectures at
Yale. And for those of you that don't know this is a prestigious lecture series that has
been going on at Yale since the beginning of time basically. So they talked about these
topics and those lectures at Yale basically led to the publishing of their second book
which is entitled The New Universe and the Human Future. This is what they have come
to talk to us about today. So without further ado, I give you Nancy and Joel.
[applause].
>> Joel R. Primack: Thank you very much, Ofer. I should perhaps explain that I have
been working for 30 years with Ofer's dad Avishai Dekel who is the leading Israeli
cosmologist, and I visited Israel many times and Avishai visits Santa Cruz every year.
He has done so essentially every year since the time when we first met.
>> Nancy Ellen Abrams: We may see an odd team to be giving a talk like this, so let me
explain how this got started. Over the years I have been watching Joel and his colleagues
in this amazing process of essentially discovering the universe. And I kept wondering
what does this mean for the rest of us. We are not living in the universe we thought that
we were in. It turns out that there is a profound connection between the seemingly
intractable global problems that we are all aware of today and the fact that we have no
big picture. We don't have an internal sense of how we fit into the larger universe. We
don't even know what the universe looks like. We don't seem to get what the cosmic
discoveries that Joel and his colleagues have been making can mean for us in our daily
lives, even on an emotional level.
We need to understand this or the consequences of this disconnect are going to become
much more severe, and our society won't really be able to take advantage of one of the
most amazing discoveries in human history, which is the story and the nature of our
universe. This is the big picture that makes sense of all of the parts including us. So by
the end of this talk, we hope that you will see that you and all of us fit into the modern
picture of the universe in astonishing ways and if we could get this, if we could begin to
act from this big new perspective, we could probably solve all of our global problems.
So how do we humans fit into the universe? Well a very common feeling today is that
we live on an average planet of an average star in a universe where one location is no
different than any other just like this drawing more or less by Escher, or that we are
insignificant motes tossed into a cold and hostile universe; and it is not really fun to think
about that, so why bother? This will show you how common this is. Here it is in Calvin
and Hobbes. Hobbes says to Calvin "what a clear night, look at the stars, millions of
them." And Calvin says "yes, we are just tiny specks on a planet particle hurling through
the infinite blackness." They think about that for a moment. It's uncomfortable; "let's go
in and turn on all the lights." Now that is not the only one. Here is the identical idea in
Peanuts. So Lucy says to Snoopy "you are of no importance, did you know that? You
are only the tiniest speck in an enormous universe." Snoopy takes it in and says "then I
might as well go back to sleep."
But this picture of the universe with a kind of a fearful little sense of human identity is
wrong. It is based on 17th century science. And we are in a golden age of astronomy
right now after thousands of years of mythological origin stories and a few centuries of
scientific sounding guesses, we actually have humanity's first picture of the universe as a
whole that was ever based on evidence, ever. And it turns out that we live on an ordinary
planet, and our place in the universe is central. Now we are not literally, geographically
central. There is no middle to an expanding universe, but we humans are central to the
principles that underlie this modern picture and this can help us get context for
understanding what we can do for altering the dangerous trends on earth. Beyond that it
can also be, and we hope it will be, the seed of a new identity that can actually motivate
us to make those changes.
>> Joel R. Primack: Until recently we had no data on the distant universe and there was
no way to test alternative theories. We didn't know the basic operating principles of the
universe or scientifically how we humans fit in. But in the last two decades all of this has
changed. Thanks to these amazing telescopes, we have massive amounts of data about
the universe all the way out in space and back in time. We have been able to test
alternative theories. These tests have ruled out all of the theories that have been proposed
to date except for one. In this talk we are going to refer to that one theory as the double
dark theory. The reason is that it is based on dark matter and dark energy, two invisible
components of the universe. The technical name is Lambda CDM; lambda represents the
cosmological constants or some exotic form of dark energy, CDM cold dark matter. As
Ofer said, I am one of the originators of that theory which is now the accepted modern
theory of how structure forms in the universe.
The double dark theory tells us that the universe is an evolving thing made almost
entirely of these two invisible substances, with just a trace amount atoms. It has a 13.7
billion year past and a future so vast that it staggers the imagination. The double dark
theory has now become accepted by virtually all astrologers. What is emerging from
astrophysics today is humanity's first picture of the origin, evolution, structure and
composition of the universe that might actually be true. To get oriented let me give you a
sort of map on several different size scales.
So of course we live in the solar system, the inner rocky planets are here. We are on the
third rock from the Sun, Earth. And then the outer gas giants. It takes light 8 minutes to
get from the sun to us and less than a day to cross the entire solar system. The solar
system is about halfway out in the disk of our galaxy. The galaxy is 100,000 light-years
across, so much bigger than the solar system. But the Milky Way galaxy in turn is just a
single dot on this much larger scale of the local supercluster. We're going to take a trip
now from the Milky Way, and in fact our own vicinity in the Milky Way, across the local
supercluster to the Virgo cluster. That is the cluster of galaxies that is more or less at the
center of the local supercluster, and it is the biggest concentration of galaxies for a
hundred million light-years around. Later on I am going to show you a simulation that is
attempting to show the entire evolution of the local supercluster, but first of all let's just
get acquainted with it by taking this little trip.
So I am about to show the first video, please dim the lights. Thank you. So we are going
to head towards this constellation that you probably all know, Orion. There is the belt;
there is the sword. Pay particular attention to that thing. So we have put all of this data
into the computer, the positions of the nearby stars including their distances and some of
these images. That is the Milky Way. So this big object in the sword of Orion is a great
nebula. It is a big gas cloud that is lit up by the stars, especially these bright young stars
that have just formed in it. As we pass the Horsehead Nebula, we are now 1500 lightyears from Earth. The Rosette Nebula is another one of these stellar nurseries.
But not all nebulae are places where stars are born. This is where a star died. We call it
the Crab Nebula and that explosion was seen on earth almost 1000 years ago. You can
see the pulsar blinking. The dust that is generated from these big supernova explosions
blocks our view in the Milky Way. So let's rise up and out of the disk so we can see the
magnificent panorama of a galaxy like our own. Because the galaxy recedes into the
distance with a large and small Medulanic Cloud and other satellite galaxies, everything
we see now is a galaxy. Here comes the great galaxy in Andromeda, the other big galaxy
in our local group, and a smaller spiral galaxy named Triangulum or M 33. As we pass
through this glowing gas cloud of M 33, we are now 2,000,000 light-years from home.
Now we are headed for the Virgo cluster which is just coming into view down here, but
we're going to take a scenic route past some of these very pretty nearby galaxies. That
was M 81 and M 82, the Pinwheel Galaxy where a supernova just went off, the Whirlpool
Galaxy. Now here again is the Virgo Cluster. We are going to first enter this long chain
or filament of galaxies. The Virgo Cluster is actually the intersection of a number of
these chains of galaxies.
Up until now we have mainly seen spiral galaxies, but now we are starting to see
elliptical galaxies, these big balls of stars. Our voyage ends at this gigantic elliptical
galaxy, M 87, which has a jet coming out of a gigantic black hole at the center. The
black hole has a mass at least 4 billion times the mass of our Sun.
>> Nancy Ellen Abrams: Well, it is very helpful to have a way to grasp the enormous
differences between the sizes in the universe. We are going to introduce a symbol that
represents the universe as a whole, but just from the point of view of size and we call this
the Cosmic Uroboros. It represents all of the sizes that things can physically be. A
serpent that swallows its tail is called an Uroboros. It is the ancient Greek term and it has
been used as a cosmic symbol by many, many cultures for thousands of years. So what
we have done is we rate all of the possible sizes algorithmically around the serpent from
the smallest size, at the tip of the tail, around to the largest at the head. So the tip of the
tail is the Planck Length and the head represents the Cosmic Horizon, which is the size of
the visible universe itself.
As we go around it and let me tell you what the icons represent. This is the size of a
supercluster of galaxies, the size of a single galaxy, the distance to the stars in the Orion
Constellation, more or less, the size of the solar system, the Sun, the earth, a mountain,
humans, a little insect, but something you can still see, a single celled creature, a
molecule, for example of DNA, an atom and the nucleus of the atom.
The Cosmic Uroboros shows us that there is really an enormous range of sizes compared
to the few that we ever actually think about. The ones we actually ever think about in our
everyday lives are in this blue section. And if you look at where we humans are in the
blue section, we are kind of on the small end, which is one of the reasons why people
think that we are so small compared to this vast universe and so forth.
But, now all of these other sizes have been discovered by science and now we realize that
when we see the whole, we humans are actually central. And we couldn't be anywhere
else, because if we were made of much fewer atoms, we wouldn't be complex enough to
have our kind of consciousness, and if we were much larger like let's say the size of the
Galactic consciousness, we wouldn't have had time because of the speed of light, we
wouldn't have had time to have many thoughts in the whole history of the universe. So
it's really only near the center of all possible sizes that the kind of consciousness that we
have can exist.
And this does tell us something about aliens. If they are out there and they are intelligent,
they are probably close to our size. That doesn't mean that they have to be five or 6 feet,
it means somewhere between a redwood tree and say a puppy. The Cosmic Uroboros
actually explains even more.
>> Joel R. Primack: Well, in particular, the distance that we just traveled in that video is
basically just about this far around the Uroboros, not a very large part of it. Different
forces are important on different size scales. On the right-hand side of the Uroboros
gravity is the important force. But on the size scale that we are more familiar with, it's
the electromagnetic forces. Those give rise to chemistry, the attractions and repulsions
between atoms, for example, what holds up mountains against the force of gravity. On
the scale of the atomic nucleus two more forces come into play, the strong interaction
which can overcome the electrical repulsion of all the protons, and the weak interaction
which among other things gives rise to some kinds of radioactivity.
Now we have a pretty good theory called the Standard Model Particle Physics of the
Electromagnetic and Weak and Strong Interactions. But there is no room in the standard
model for dark matter, and we now know that dark matter is most of the mass of the
universe. So we imagine that there must be new phenomena on still smaller scales that
the dark matter is associated with. That is with this DM question mark is about. Of
course we don't know what the dark matter is, so there might be some surprises lurking.
Now what about this tail swallowing? What is going on there? The hope is that when we
really understand how everything is put together, there will be connections between the
smallest and the largest. That actually happens in superstring theory. If you try to go
smaller than the Planck Length in superstring theory, you remap to bigger scales, so there
are connections that are built in there between the small and the large.
The trouble is the superstring theory doesn't make predictions that can easily be tested
and so we don't really know if that unique theory that seems to be the one way to make a
finite theory that could include all of the forces, we don't know if it is really right. So we
have a lot more work to do.
>> Nancy Ellen Abrams: The scale models never work like the real thing because every
phenomenon and every animal can only operate in the size range where it actually is, and
this turns out to be a universal pattern. You could call it the law of Uroboros thinking. It
applies to everything and that includes us. Huge changes in scale exist not only in the
sizes of the things, but in the complexity of human interactions, and this helps explain
Friedrich Nietzsche's famous epigram "madness in individuals is something rare but in
groups, parties, nations and ethics, it is the rule." Everyone has probably noticed that
individuals can be kind, generous, wise and yet, a committee of those same people will
not be kind, generous or wise, and even less so for a large organization like a country.
This may seem odd. I remember a New York Times headline during the crash that read
"have banks no shame?" And the answer is no. A bank can't have shame; it is not human
and it cannot have human emotions by definition.
One way to make this easier to understand is to think of it in reverse. And that is that all
of us are made of elementary particles, but we don't behave anything like elementary
particles because with the increase in complexity, we have acquired completely new
properties and the behavior of elementary particles has disappeared. So now let's take a
very fast trip around the cosmic Uroboros from a scale larger than super clusters of
galaxies all the way down.
>> Joel R. Primack: Another video, please dim the lights.
>> Nancy Ellen Abrams: You will see on the right here is a kind of a clock and that
points to the size that we are looking at.
[video begins].
>> Joel R. Primack: So now let's take another voyage. This time not the 60,000,000
light-years from where we are now to the Virgo cluster, but a much longer distance, all
the way out to the Big Bang itself. This is based on data from the Sloan Digital Sky
Survey, the biggest mapping project in history. We now have measured the ridge shifts
of over a million galaxies and we can put those into space and visualize the distribution
of these galaxies. So one more video, please dim the lights. We are going to now place
the local group at the center and look at structures on scales of billions of light-years.
[video begins].
>> Joel R. Primack: We are rapidly moving away from our local vicinity of the universe.
Only certain directions have been mapped. The mapping is done with a telescope in
Apache Point New Mexico, and we get a big pile up of galaxies in a certain direction.
You can already see there are certain regions that are more or less empty of galaxies. We
call them cosmic voids and there are walls of galaxies that surround the cosmic voids.
But to get a better sense of the three-dimensional distribution, let's rotate the image. You
see, it's like slices through a sponge. That's how the galaxies are distributed on a large
scale and that is also what the Lambda DDM, double dark theory predicts. Now we are
seeing the quasars, very bright. And now a view you can only get with the help of
computer animation, we are looking at the Big Bang from the outside. The colors
represent the slight differences to the millionth of a degree in the temperature of the heat
radiation of the Big Bang measured by the Wilkinson Microwave Anisotropy Probe,
WMAP, for short, NASA's satellite that has been doing this now for almost a decade. So
you see the galaxies, the quasars and the heat radiation of the Big Bang all superimposed.
>> Nancy Ellen Abrams: However you notice that at the end of this video we are looking
at the universe from the outside. If we want to get any kind of accurate sense of how we
fit into the universe, we have to start looking at it from the inside because that is where
we actually are. So we have this other symbol, now this represents the universe as a
whole, but only from the point of view of time. We call these the cosmic spheres of time.
Because light travels at finite speed, when we look out in space, we are looking back in
time. So this symbol places us at the center, there we are today, and the way to interpret
it is that these spheres represent earlier and earlier epics in the history of the universe, so
that today is the center and the first sphere out is the era when the solar system and the
earth were forming. The next sphere out represents the era when the big galaxies that
look like the ones we are in formed. The next sphere out is when the bright galaxies
began to form that don't look so much like the ones that surround us today, because this is
the very early universe.
Before that there is a long period of what they call the cosmic dark ages before the
galaxies had formed. This is the cosmic background radiation that you saw from the
outside in the earlier video and the cosmic horizon which is the Big Bang itself. So the
symbol places us at the center, but it still looks like it is up there on the screen and we are
all just sitting back here looking at it. So you have to use some imagination on this. Put
yourself in the middle. Put yourself at today, and then in your imagination close the
spheres around yourself. We are all immersed in the history of the universe; we are at the
center of our past. The past is not over; it is racing away from us at the speed of light like
ripples from a pebble thrown into a pond, except that is two-dimensional. The past is
racing away in all directions so it is like spheres and those are the spheres of time.
So what is this amazing universe made of? Well, this is what the Hubble space telescope
shows us. The picture is beautiful but it is misleading, because all we see when we look
at all these galaxies is half of a percent of the cosmic density. The other 99 1/2% is
invisible. So now I am going to introduce another symbol. Now this also is going to
represent the universe as a whole, but this is from the point of view of what is it made of.
This symbol, obviously you recognize this. We borrowed it from the back of the dollar
bill, but the proportions are accurate. So it actually does work. This represents all of the
visible matter in the universe. The large base of the pyramid is the hydrogen and helium
that came straight out of the Big Bang and that is what became the first stars. And the
floating capstone at the top represents all the other visible atoms, the entire rest of the
periodic table of the elements.
When stars die in supernova, all of these other elements get blown out into space and so
they become what is literally stardust. And the reason there is and eye here, the reason
we want the eye here is that intelligent creatures can only be made of stardust. It is the
only thing that has complicated enough chemistry to create our kind of consciousness.
So that eye represents us. The visible matter that this pyramid represents used to be what
people thought was all that existed, but it is not. It is actually less than half of a percent
of what is out there.
>> Joel R. Primack: Most of the universe, as we have been saying, is invisible. So now
let's look beneath this pyramid at the enormous invisible stuff that the universe is mostly
made of. It turns out there is about 10 times as much invisible atoms as there is visible
atoms. It is in between the galaxies. It is not stars. It is not lit up by stars. But we know
that it is there. We can actually measure the effects of this stuff and we have seen traces
of it at earlier times in the history of the universe. There are five different ways that we
can do the census of atoms and they all agree. So we are really quite confident that we
know the relative amounts of the visible and the invisible atoms. Most of the mass in the
universe, however, is not made of atoms or any of the parts of atoms. We call it cold
dark matter. We don't know what it is made of. Many years ago I proposed that it's
connected with superstring, what has become superstring theory, supersymmetry, but we
don't have the evidence to tell whether that is the right picture or not, although it is still
the most popular idea.
The dark energy is by far the largest part of the density of the universe. As the universe
has expanded, more and more space is filled with this dark energy until the dark energy
now is the dominant component in the universe and that is what powers the expansion of
the universe. We don't know what the dark energy is even less than we know what the
dark matter is, but we know enough about how they behave that we can put them in
supercomputers and evolve the picture and make all kinds of detailed predictions, and we
will show you some of those simulations in a few minutes.
>> Nancy Ellen Abrams: A way to think about this is if you imagine that the entire
universe is filled with an ocean of dark energy and on that ocean there sail billions of
ghostly ships made of dark matter and only at the tips of the tallest masts of the largest
ships are little beacons of light and those little beacons of light are the galaxies that we
see. We can't see the ships and we can't see the ocean, but we know that they are there
through theory, specifically the double dark theory. But you are going to be able to see
the invisible very soon. So here we have a guy sitting on a stoop saying to his friends,
"quarks, neutrinos, Mesons all those damn particles you can't see that's what drove me to
drink. But now I can see them." And the reason that this is appropriate is that we now
can see also what can't be seen thanks to supercomputers. So the next two videos
occasionally confuse people, so I just want to say that the earlier videos were images,
optical images captured by telescopes, but in the next two, everything that looks bright
and light is actually representing density because we are showing you just the dark matter
which is completely invisible. So the brighter a spot is in the next videos, the denser the
dark matter is in that region.
>> Joel R. Primack: Dark matter is weird stuff. If two blobs attract each other, they
come together and they can go right through each other, yet their gravity won't let them
get too far apart after that. We're going to show you a computer simulation of dark
matter and dark energy in a small portion of the expanding universe. You will see that
the central region initially expands, but its dark matter starts falling together and
eventually forms what is called a dark matter halo, just a blob of dark matter. Inside the
halo is where a galaxy or if it's larger, a cluster of galaxies will form. The space inside
the dark matter halo will stop expanding. You will see that in the visualization. But the
space outside the halo continues to expand. So one more video, please dim the lights.
Thank you.
[video begins].
>> Joel R. Primack: So expanding, but you see that in the center here things are starting
to fall together and not expand. This region still is flying away. To recap, starts very
smooth, expanding, it is still expanding; this is now a little over 2,000,000,000 years after
the Big Bang, but by about a little over 6 billion years, about halfway to now, this region
has stopped expanding and things are falling into it, but this blob is now expanding away.
The common terminology is that there is outer space which just means beyond the Earth's
atmosphere. That is not very useful distinction. A more interesting and useful distinction
is the distinction between what we could call tame space, the regions where gravity is
holding things together. Our galaxy is not expanding. The local group of galaxies isn't
expanding, and in fact our galaxy is racing toward Andromeda, or better, they are racing
towards each other, so our local group is still contracting. But other bound groups of
galaxies and clusters of galaxies are flying apart from each other because the more or less
empty space between them, empty of stars, also of dark matter, not completely empty, but
much lower density, is controlled by this dark energy, which causes space to repel space
so that there is more repulsion the more space there is, and so this leads to a very rapid
expansion. So that is wild space.
You may wonder looking at a visualization like this of blob of dark matter, how big that
is compared to a galaxy. So this is a high-resolution simulation of the Halo of a Milky
Way sized galaxy. And this is the visible galaxy. Notice that the halo is filled with these
little blobs. Those, the bigger blobs will represent the dark matter halos of those small
companion galaxies and interestingly, when we compare the distribution in space and in
velocity of the predicted distribution of these halos that the satellite galaxies and the real
satellite galaxies, the agreement is really remarkably good. It is another one of the
reasons we take this theory very seriously. On the other hand you see a huge number of
these little blobs and it remains to be seen how many of these dwarf galaxies are actually
visible once we can have bigger telescopes to see even the faint ones.
In the next visualization we are not going to show the expansion of the universe, and the
reason is if we tried to show that on a large scale, you wouldn't really be able to see what
was going on until it got pretty close to the present time. This shows how it would look if
we tried to do it the way we just did showing the universe expanding in size, a region of
the universe expanding in size. The problem is you wouldn't be able to tell what was
going on until it got to be a pretty good size. So instead of showing the expansion, what
we're going to do is take out the expansion by blowing up each of these images to the
same size as the final image. So this time we are not going to show the expansion
although it is built into the calculation.
What you can see when you blow up these images is that initially the dark matter starts
very smooth, but very quickly it becomes quite irregular. It is attracted to what we
sometimes call wrinkles in space, more on that in a few minutes. But first let's look at the
next visualization, so please dim the lights. What this is, is a visualization of the
evolution of our local part of the universe including the Milky Way. We will show you
the Milky Way towards the end.
[video begins].
>> Joel R. Primack: Starting with the Big Bang, the dark matter starts to conglomerate
very quickly. It forms these clumps, these halos of dark matter. They tend to move along
the filaments. So here what we are doing is a fairly small simulation of this type. It only
took about 100,000 CPU hours. It is 1 billion particles fairly low resolution. The
simulation is now finished and now what we are going to do is fly through it to get a
sense of how the galaxies are distributed. You saw in that voyage to the Virgo cluster
how the galaxies form these filaments, and if you compare statistically the actual
distribution of galaxies measured for example by the Sloan survey with what the
simulations predict, the agreement is spectacularly good. We haven't found any
disagreements at all. See how a cluster forms at the intersection of these filaments.
Now we are actually passing the Virgo cluster and the Milky Way. We will come back
and you will see it in a little more detail. Where were those things that I just mentioned?
So that little dot is the Milky Way and the one above it is the Andromeda galaxy which
we also call M 31. There is the Virgo cluster. And there are some of the filaments
leading into the Virgo cluster. And there is a smaller nearby cluster called the Fornax
Cluster. So now we will just show the end of that last visualization, and you can watch
the Milky Way go by.
[video begins].
>> Joel R. Primack: So there is the Milky Way. Now you just saw how the cosmic web
we call it of dark matter forms and that at the intersections of the filaments the density is
much higher, and that is where clusters of galaxies form. Our fly view actually passed
the nearest cluster, the Virgo cluster, but why does the dark matter have this filamentary
structure on large scales? The answer lies in the instant before the Big Bang. According
to our best current theory on this called Cosmic Inflation, just before the Big Bang, or if
you like at the earliest moment of the Big Bang, there was a very brief period, much less
than a second, during which the universe expanded exponentially. In other words in each
successive equal unit of time it doubled in size and then doubled again and then doubled
again et cetera. In exponential or inflationary growth, the more there is, the faster its rate
of growth. And so it becomes explosive. This is exponential growth, but it ended
abruptly at what we call the Big Bang. After which the universe continued to expand but
much more slowly, not exponentially, but now not even linearly with time.
According to Cosmic Inflation theory, in this tiny fraction of a second before the Big
Bang, the universe expanded just as much in powers of 10 as in the 13.7 billion years
later. So there again is the cosmic Uroboros and it starts the universe, our little visible
universe, starts nearly at the Planck scale and it grows to about the size of a baby. And
then in the 13.7 billion years since then, it's grown up to the size of the entire visible
universe. Cosmic Inflation is the only theory that we have discovered so far that explains
how the Big Bang could've gotten started, how the right initial conditions could have
been generated for the Big Bang to have turned into the universe we see around us.
Cosmic Inflation predicts exactly the small differences from place to place in the early
universe that will produce the galaxy distribution that we see together with dark matter
and dark energy.
The way the cosmic web itself came into being, was that quantum effects randomly
occurred during this period of Cosmic Inflation. At the Big Bang, these quantum effects,
these quantum fluctuations, were permanently embedded in space time in a unique
pattern that we can think of as little wrinkles, slight differences in density from place to
place. The pattern has continued to expand slowly as the universe itself has expanded
and along the expanding wrinkles, the extra density made the dark matter expand a little
bit more slowly than in the regions in between these slightly higher density regions, and
over a long period of time these slight differences in density would start out about 10 to
the fifth, yet expanded into huge differences in density and give rise to the structure that
we see. So the pattern of wrinkles has been the blueprint for the large-scale structure of
our universe. It was created during the brief inflationary moment, and the entire universe
is developed on that skeleton.
>> Nancy Ellen Abrams: So what does Cosmic Inflation have to do with our immediate
human future? The greatest challenge of our time is to figure out how humanity can
make the transition worldwide from exponential growth to a sustainable impact on the
earth. The way that rampant Cosmic Inflation transformed quickly into slow expansion
at the Big Bang, could give us a new way of thinking about this. It could give us a new
model for how to exit from exponential growth. Cosmic Inflation was exponential
growth in the size of the universe, but exponential growth can also happen in biology and
sometimes a species gets into runaway reproduction. It over consumes the resources of
its ecological niche and it dies. So take, for example, a hypothetical bloom of pond scum
that doubles every day. It starts to grow very slowly, but it speeds up and until the last
couple of days, the pond can look perfectly nice. The fish are happy and swimming
around, but on the last day the scum chokes off the whole pond and everything dies. This
graph just represents the last 10 days of that.
What most people don't understand because it is really counterintuitive, is that by the
time an exponential threat becomes noticeable at all, there is almost no time left. The
pond scum doesn't seem to represent any danger to the pond until the next to the last day.
This is a graph of the human population over the last 2000 years, and we humans are
actually in worse shape than the pond scum in some ways, because not only is our
population increasing rapidly, but the amount of resources used per person is also
expanding exponentially. Each person in the United States consumes their weight in
resources every day and we are already reaching limits, and we need to take action now
based on a much longer-term view.
In 1976 I was a young lawyer at the Office of Technology Assessment of U.S. Congress
which was the science advisory office. It was shut down by the Republican revolution of
1994. My office knew in the 1970s that the earth was warming, that oil was running out,
that the health system was unsustainable. Our job was to think about the long term. But
the longest term that anyone ever thought about was 30 years and the members of
Congress and the Senate that we worked for hardly even took us seriously because they
thought that was such a luxurious and unrealistic timeline.
Well, the fact is that those 30 years have now passed and every one of those problems is
not only getting worse, it is getting worse faster and faster. When it comes to long-term
concerns that we are facing today like global climate change, a lot of people would just
prefer to change the subject. But we can't afford to change the subject. We really need to
have a way to bring accurate and up-to-date scientific thinking into the political sphere.
So the political controversy is about what should we do and who should do it, not about
what is real. We would have a much better chance of cooperating, not to mention much
better results, if we could simply share a picture of physical reality so that all options
being fought over are at least physically feasible.
So very briefly I just want to give you one example. Let's take nuclear power which is
being advocated today as a carbon free energy source. After the Fukushima disaster this
looks like a terrible choice. But let's see what's on the other hand. We have a potentially
much bigger crisis if humanity keeps pouring carbon into the atmosphere, the climate
becomes chaotic. The ocean currents change and around the world there are extreme
droughts, wildfires, hurricanes, floods, crop failures, diseases appearing where they never
were before, refugees both human and animal roaming the globe. So on second thought,
if nuclear power could seriously help us avoid this fate, we have to reconsider and ask
could it be made safe and economically competitive? How so? Which version of nuclear
power?
So here's the problem. Who can we trust to answer these questions? You can't trust the
energy companies because the bottom line is their goal. There is really no one in the
relevant government agencies who can answer because they are juggling all of these
economic and political pressures. So when I was working in Washington I invented
something called scientific mediation, which is a very novel procedure that governments
can use in this case. What happens is a government agency that needs to make a decision
based on science, and the science is controversial as it almost always is, brings together a
scientist representing both sides of the controversy, and rather than letting them talk past
each other which happens all the time, they use a mediator to write a joint report where
they explain four specific things.
What are their areas of agreement? Let's narrow the dispute. What are the major points
of disagreement? And then the key idea is that on each of their points of disagreement,
they have to agree on why they disagree. This is an interesting step because at this point
the biases that each scientist has, and I am not trying to disrespect scientists in any way,
but they are human beings. We all have our biases; we all have our economic leanings
and so forth. These things tend to fill in the gaps where the science is unfinished and
these things tend to surface when they try to explain why they disagree. And then finally,
they summarize the essential research that still needs to be done.
Scientific mediation was first used by the Royal Energy Commission in Sweden to
determine whether the Swedish utilities plan for nuclear waste disposal was scientifically
adequate, and I acted as mediator. The scientific mediation was so fruitful that for years
afterward it was regularly used in all technical controversies by the Swedish Department
of Industry. It is not an expensive procedure. It is not hard to do. It is really extremely
simple, but, and this is a big but, the agency has to really want to find out what the
scientific truth is and not just be looking for scientific sounding cover for what they
already want to do. But if we could do something like this, it would tremendously
advance our whole society's level of politics.
So is this kind of thing impossible? Are we just talking about pie-in-the-sky here because
so many people in our own country don't know anything about science and don't even
care that they don't know anything about science. Many of them don't even believe in it.
But the bottom line here is nothing in physics says that the human race can't succeed, and
resignation and cynicism are really the biggest enemies. We can begin to think
cosmically. We can begin to have a much bigger perspective especially a time
perspective on our political decisions. We need to raise our thinking to the level that our
challenges demand. On the night of the 2008 presidential election, then President-elect
Obama said something very interesting in his speech. He challenged the country to think
100 years ahead, something I had never heard a politician say before. I don't know if you
recall his acceptance speech; he talked about this woman Ann Nixon Cooper who was
106 years old, and he described the enormous panoply of changes that had taken place in
the world during her lifetime. Let me just remind you of that.
[video begins].
>> President Obama: America we have come so far. We have seen so much, but there's
so much more to do. So tonight let's ask ourselves if our children should live to see the
next century, if my daughters should be so lucky to live as long as Ann Nixon Cooper,
what change will they see? What progress will we have made? This is our chance to
answer that call. This is our moment. This is our time.
>> Nancy Ellen Abrams: Well, whatever you may think of what is happening today, he
was absolutely right on that night when he basically proposed that we need to start
thinking seriously about the 22nd century. So we are, Joel and I, rather than calling back
just the next century as a sort of abstract amount of time, we are going to call that the
Melia Sasha horizon, because these kids are actually alive today. We are talking about
the lifetimes of actual US citizens. A hundred years is not some fabricated amount of
time. So let's let Melia and Sasha represent the interests and the characteristics of today's
little kids and recognize that the year 2100 is a real-time. It will arrive for them, even
though many adults today economically discount it as though it were some kind of low
probability event. If we took into account the consequences of our actions out to the
Melia Sasha horizon, that would be the first step toward a cosmological perspective.
>> Joel R. Primack: So let me briefly summarize the situation with carbon dioxide, one
of the challenges we face. This chart shows the amount of carbon dioxide in the
atmosphere for the last 2000 years. We actually can measure this for the last 800,000
years from little bits of atmosphere that are trapped in the ice in Antarctica. And we
know for the last 800,000 years the amount of carbon dioxide has never exceeded 300
ppm until very recently. The red line shows the human contribution, and ever since
humans started burning carbon fuels, around 1800, the beginning of the Industrial
Revolution, the amount that we have injected into the atmosphere has doubled roughly
every 30 years. It is now shooting up extremely rapidly and obviously increasing the
amount of carbon dioxide in the atmosphere very rapidly. If it continues at the current
rate of doubling, that will be a factor of eight increase in the present century. The
environmental consequences of both the carbon dioxide increase and the other
exponentially increasing impacts on the earth will be catastrophic. This is from a recent
report of the US global change research program. This part just focuses on the effects of
the United States. They considered a number of different scenarios. This was one of the
most optimistic scenarios and this is basically business as usual.
Now since 1900 the average temperature on earth has only increased about a degree and a
half Fahrenheit. The prediction is that across the country the increase is going to be 4 to
6° by the Melia Sasha horizon, if we really try hard to control the amount of carbon
dioxide we the United States, but also the other countries that are producing a lot of it
including the countries that are starting to produce a lot more like India and China,
Seattle actually comes through fairly well with only about a 2° increase. In other words
something like double the amount of warming we've had so far, but across much of the
country, it is considerably more than that, and the southwest will basically have droughts
that are much worse than what we have seen so far. And that is the optimistic scenario.
That is what we are almost committed to based on what we've done so far.
This is what we get with business as usual, basically an average of about 9° temperature
increase across the United States. Now there is very little dispute that global warming is
happening among the scientists that study this sort of thing. The main thing that we don't
know is how to predict accurately what the consequences are going to be of various
future scenarios. And that is why there is a fairly sizable range here where respectable
opinion differs, but it is clear that this is absolutely catastrophic and this is pretty bad.
>> Nancy Ellen Abrams: These horrible consequences are not inevitable, not all of them.
And the real question is, are we smarter than pond scum? The pond scum model is not
the only way the exponential growth can end. Cosmic Inflation gives us this other model.
Unlike the pond scum when the exponentially inflating universe hit its limit, it didn't just
die. The inflationary rate of growth stopped, but growth continued. The universe
essentially slammed on the brakes, slowed to a crawl and just kept going for billions of
years. Inflation that is transformed to slow and steady expansion can go on indefinitely.
The end of inflation could be thought of as the end of adolescence. It is a kind of coming
of age, and from then growth needs to be not physical but intellectual, emotional,
spiritual, relational. The universe’s inflationary period ended abruptly at the Big Bang,
but this was good for us, because it was only after Cosmic Inflation ended and the cosmic
expansion became relatively slow, that the universe entered its truly creative and longlived phase.
Slow growth brought forth galaxies and stars and planets and life. All of this happened
after inflation, ended and this is what could be true for us. The fundamental character of
the universe has been to grow in complexity. But growing in complexity takes a long
time so long slow growth is really what humanity needs to develop a sustainable
civilization. But there is also a warning in the cosmic model and that is that the random
quantum inflation Joel was talking about got frozen at the Big Bang into permanent
wrinkles, and those became the structure of space-time where the galaxies formed and
similarly countless political and social decisions that are being made all around the world
right now in these final years of inflationary growth may look random. They may look
like silly trends and so forth, but in fact they could end up getting frozen into the future of
our species and our planet. We really need to think much more deeply about decisions
that are being made today. There is a lot of partisan mudslinging going on in Washington
and sometimes you just want to throw up your hands in frustration, but that would be one
of the irreversible errors. Today's actions and failures to act could reverberate into the
distant future far out of proportion to the thought that is going into them. If we wait until
the consequences of runaway growth and resource use become obvious, it will be too
late. We need to start to think now for the long-term, and if we do we could avoid the
worst consequences for our children and their descendents. Our descendents could live
comfortably on Earth for billions of years as long as human creativity stays ahead of our
physical impact on the planet.
>> Joel R. Primack: So let's look at our long-term future. In a couple of billion years our
galaxy is going to sideswipe the great galaxy Andromeda. They will go pass each other,
but their gravity will pull them back together. These are scenes from a visualization that
I don't have time to show you. The centers will merge and the stars will become a more
or less spherical ensemble that will be an elliptical galaxy that we could call Milky
Andromeda. Now we just achieved the technological ability to see the distant universe.
But as the expansion of the universe accelerates, the most distant galaxies will disappear.
As the universe gets older, less and less of the universe will be visible to our descendents.
Milky Andromeda will eventually become all that is visible. The magnificent panorama
of the ultra deep field, we previously showed it to you in visible light. This is the new
camera that the astronauts installed on space telescope in 2009 shows. This is the wide
Field camera three infrared ultra deep field. This magnificent panorama will not be
available to the intelligent creatures that live in that future time, and in fact their only
photos of the distant universe will be the ones that are left by the people like us that now
can make these images.
The future of the entire visible universe therefore, could depend on us. If we humans
begin to think cosmically, our descendents could be the source of intelligence for the
entire universe. If we early 21st century earthlings now begin to think cosmically with
the goal of a long-lasting civilization, it's likely that some of our distant descendents will
move outward into the galaxy and could eventually radiate life and intelligence
throughout it. So cosmology gives us a new yet multibillion-year-old identity. This is
discovery of who we have always been but could never know or even imagine without
the discoveries of modern science. Cosmology gives us powerful new concepts that let
us think accurately for the first time on large enough scales to understand the true extent
of our universe and of our problems. There is a symmetry in our consciousness of past
and future. People who don't know about our past, can't possibly conceive of the longtime future. The key to visualizing a long-term future for humanity may be to grasp our
immense cosmic past. This may be the biggest contributions that cosmologists like me
can make to the world.
>> Nancy Ellen Abrams: Around the world as environmental disasters escalate, many
more people may begin to recognize that to protect humanity, we really have to start
opening our minds to something that people have not been thinking about, and that is the
possibility of an overarching, unifying cosmological vision for Earth that can help all of
us humans with all of our divisions and uncontrolled emotions to cooperate for the longterm survival of our descendents. There is no law of physics that says that we can't thrive
for hundreds of millions of years. And cynicism about the future is really an insult to all
young people. We can begin to think cosmically. Fortunately these discoveries have
been made at a time, at this pivotal time, when we have not yet committed the future.
So this is a radical idea, but for the first time in human existence it is possible. So let's
just close with a picture of where we really fit in this universe.
>> Joel R. Primack: Please dim the lights for this last video.
[video begins].
>> Nancy Ellen Abrams: If we wake up to the reality of our universe and our current
predicament on earth, if we can expand our interpretations of our religious traditions to
encompass new knowledge, if we can begin to teach this picture to our children and
integrate its principles where appropriate into our thinking and our art, then we will be
thinking cosmically and we will become ancestors worthy of honor 1000 years from now.
>> Joel R. Primack: Thank you very much for your attention. Think Cosmically, Act
Globally, and Eat Locally. This is the new book that we recently published. We would
be happy to take questions and also of course to sign copies of the book.
[applause].
>> Joel R. Primack: Let me show you the credits for the visuals and also for the music,
and you will notice that several of the pieces are actually composed and performed by
Nancy, some of those on those synthesizers that Ofer was telling you about. Any
questions? Yes?
>>: I've heard about this notation of 4% of whatever is out there that is visible to us. I've
been struggling with this notation that 96% of whatever it is that we don't know. How
would be so accurate that it is 96% of all [inaudible]?
>> Joel R. Primack: As I said, first of all the numbers are what we actually see, the
visible stuff and by that I mean not only the stars, but the gas, the dust, the things that
absorb light as well as emit light. All of that together is just half of 1% of the cosmic
density, not 4%, but half of 1%. The 4% is all of the atoms, about 4 1/2% actually.
There is five different ways that we can measure the atomic contribution and they all are
done at different times in the evolution of the universe. So the theory of Cosmic Inflation
plus cold dark matter predicts that the distribution of that heat radiation of the Big Bang
on different angular scales. It predicts that the characteristic angular scale is about 1°,
that the regions of comparable temperature tend to be about 1° across in the sky. That is
twice the width of the full moon. That is exactly what is seen. The prediction was made
long before the observations.
And then it turns out that half of a degree is disfavored. A third of a degree is favored. A
quarter of a degree is disfavored according to the theory. As the data came in, it is
exactly as predicted. Every single independent data point came in exactly as these
predictions that were made long before the data was available. This is one of the many
reasons that we take this theory so seriously. The height of the first two peaks, the 1°
versus the third of a degree, that is the second peak, is actually mainly telling us the
amount of ordinary matter of atoms in the universe. It is a complicated story but that is
what actually comes out of the theory. So that is the first way that we can measure the
amount of ordinary matter in the universe. In other words of atoms.
Then we can look at the amount of light from distant quasars that is absorbed by clouds
of neutral hydrogen. That is the second way. And that hydrogen actually is all, is
practically all of the stuff in the universe, all of the atoms I mean. And so that gives us a
completely independent way of measuring how much stuff there is and that agrees with
that first way. And then we can go on and I can tell you the other ones, but let me not do
it right now, but I will do it if you want me to afterwards. But the point is that everyone
of these different methods of measuring the amount of ordinary matter and also
incidentally the amount of dark matter and dark energy, they all agree. And they are
completely independent. That is why despite the fact that most of the universe is
invisible, and it wasn't obvious that we could figure this complicated picture out only
being able to see the smallest percentage, the fact that our theory agrees so well with the
observations is why we take this so seriously. And not just people like me who helped to
create the theory, but also the observers who are professional skeptics and tend to
disbelieve all theories to start with. I think they basically are convinced that we have got
this part right. So it is very counterintuitive that the universe should be so invisible and
also that we could figure it out, but I think that both things have happened. Nancy, why
don't you pick the next person?
>>: You had mentioned about not thinking cynically to be able solve problems. That
makes sense because it would be counterproductive. But you talk about exponential
growth been responsible for destroying many different ecosystems, maybe even our own,
and I am kind of wondering if you look at our current ecosystems with our current world
driven by exponential systems, we have gotten ourselves into a mess where innovation
over the last 150 years, the Industrial Revolution, technology revolution. If you look at
our money systems, look at our financial markets, they all require exponential growth to
be put in, otherwise things break. And if you look at our current financial problems it is
because the fact that that system is breaking down that we are having all of these
problems. Not only is that required for our growth, but we have exported that to the rest
of the world and we have started to make the rest of the world dependent on it. We are
taking other social models, like even China for example, it is still centrally controlled, but
they are moving towards a capitalist system that is dependent upon the same type of
growth. How do we get out of this self-made mess that we have made for ourselves with
the thinking that we need to do to solve the problems is counter to what is allowing us all
to drive BMWs or keep roofs over our heads or plan for the future, grow money for
retirement or whatever?
>> Nancy Ellen Abrams: Well this is obviously the great question, how do we do it? But
what we are trying to do here, because we are not experts in every field. What we are
trying to do is to give a big picture. Let me just give you an example of how this would
work in a simpler context. If you are trying to get a deal between two different sides and
they really don't agree on anything, the last thing, and you certainly are not going to start
by trying to get them to agree on what to do on even the smallest thing, because they
won't agree on anything. The way to get them to agree is you start to get them to agree
on really big basic principles where they really can't see how those principles are going to
get applied, but obviously the principles are right. So you get some kind of an agreement
there. And then gradually you work inward to the implications of those principles and
having agreed here, they have to agree here, and you can gradually work to something
which is practical.
And I think that that is going to be the way that this has to work. We have to start with
big principles, big ideas. Do we want to save the planet? Do we believe that there could
be a multibillion year future? I mean if everybody on the planet simply agreed that we
could have a multibillion year future if we could get through the next few decades, that
would be a huge step forward, without anybody deciding what we are actually going to
do.
So what we have to do is we have to work from the big principles downward and what
we want to do is introduce the big principles, make them accessible to everybody even
little kids, and the creativity of the world really has to be part of this. It takes a lot more
than a village to save the planet. It takes the whole planet. I mean it's going to take
people all over the world in every field working towards this, but we have to have some
kind of overarching picture that we can start with and that we can agree on. I am not
saying that by telling people how the universe works that they are going to change their
economic or any kind of picture, because information doesn't change the way people
behave. What changes the way people behave is when they adopt a new identity. When
they find an identity that is really much more attractive to them than the one that they
have had. And we have discovered that we all have a cosmic identity. It is now a
meaningful word to say a cosmic identity.
Working from that I think we could begin to have a movement in this direction, but yes,
it will take a huge amount of creativity to figure out how to implement these ideas.
Thank you
>> Joel R. Primack: Is going to require that people become a lot smarter and that is your
business here, as I understand it. Not only that, to the extent that the industrialized
countries like the United States move away from an industrial toward an informationbased technology, the resource needs are not that great. We need to get the rest of the
world into that mode as quickly as possible. And of course we will have to satisfy
demands for the basic necessities of life and some of the luxuries, but we will have to do
it in a smarter way.
>> Nancy Ellen Abrams: And fairer.
>> Joel R. Primack: The fellow in the back.
>>: Sure. Does the presence of dark matter and dark energy suggest a fifth fundamental
force? One. Can the presence of these two things supply a suggestion to a possible
mechanism to explain quote spooky action at a distance? And why is gravity so weak?
>> Joel R. Primack: Those are great questions. The spooky action at a distance of course
is a quantum mechanical phenomenon, and quantum mechanics to those of us who are
quantum machinations isn't particularly spooky. That was something that really bothered
Einstein who first really appreciated that there is this phenomenon that we now call
quantum entanglement. But of course if quantum computing ever succeeds, it is going to
be totally based on that. So we have to embrace it. And I don't think it has anything to
do with dark matter and dark energy. Now fifth force, very likely, there is something else
going on that we haven't yet put into our theories. Whether you want to call it a fifth
force or--we don't know exactly what it is. Supersymmetry is the basis of superstring
theory and much of modern attempts to go beyond the so-called standard model of
particle physics. Supersymmetry is the idea that for all of the fundamental particles that
we know and love, the photon, the electron, quarks et cetera, there are partner particles
that haven't been discovered yet that therefore must be much more massive and that have
properties closely related to the ordinary particles that they are the partners of.
So for example, there would be what we call selectrons that would have the same charge
as the electron, but must weigh a great deal more, maybe 1 trillion electron volts, 1000
times the mass of the proton. There might be photinos, partners of the photon and similar
partners of the other force particles, the vector particles that carry the forces or the
graviton could have a partner called the gravitino. The photino and the gravitino are two
examples of what could be the dark matter particle. In most versions of supersymmetry
the lightest of these particles is stable, the lightest of the super partners, and therefore it is
either a great candidate for the dark matter, or if such a thing does not exist, it probably
means that this whole supersymmetry idea is false.
It was a paper by Heinz Pagels and me that first pointed out this idea back in 1982. So
since supersymmetry is so popular with particle physicists, that is the most popular idea
for what the dark matter is, and indeed the exchange of these super partners gives rise to
new forces beyond the ones of week already know. So we don't usually call it a fifth
force. That was a term that was used to describe something that turned out to be wrong,
but yeah, some kind of new force. I forget what your third question was.
>>: Why is gravity so weak in comparison to [inaudible]?
>> Joel R. Primack: Ah yes, why is gravity so weak? What we can tell you is if gravity
weren't so weak, then the universe would be utterly different from the way that it is and
probably inhospitable to creatures like us. So the answer that is probably the most
popular answer to that question is the so-called anthropic one, that in order for creatures
like us to exist, you have to have this huge gap between the strength of gravity and the
strength of the other three forces that we know. That is the kind of explanation that
doesn't satisfy most physicists that would like to have physical explanations for physical
phenomenon. We don't really have a complete physical explanation for this. We are
hoping that out of superstring theory, there will be such an explanation because in
superstring theory there is only one scale, so all of the other relative scales, for example
of the different forces, ought to come out of the theory.
The trouble is in order to make predictions from superstring theory which really works in
10 or 11 dimensions, one time and the rest space dimensions, we have to figure out how
to make predictions that are specifically for our three dimensional large-scale universe
and no one has figured out how to do that in a way that corresponds to the reality that we
are familiar with. It may lurk in superstring theory. There've been a number of
breakthroughs in superstring theory every few years, and our hope is that somebody will
be clever enough to figure out how to solve this so-called compactification problem in
superstring theory. But it has not been solved yet. So we don't know the answer that
question. Nancy?
>>: [inaudible] your statement that [inaudible] atoms have different properties but they
become a group [inaudible]. So using that analogy as individuals we all have good ideas
and we want to do the best for mankind, but as we become a nation our relation, whatever
that madness is inherent. So given that state can we expect what does it take for the
entire cluster of human beings coming together to change the totality of the system
relative to the individual?
>> Nancy Ellen Abrams: [laughter] I wish I knew the answer to that one. But you know
in evolution when very small microorganisms came together to form cells and small
animals came together to form larger animals, they began to cooperate whereas they had
been in competition before. And evolution takes a long time. The most important thing,
the absolute most important thing for everybody to remember is that we need time. We
can solve all of our problems only if we can create a sustainable civilization that gives us
the time to figure out how to do it. So the long-term view is the most important thing that
people need to have. How it's going to work together, I don't know but that’s been the
story of evolution, that smaller individuals have come together to form groups, that then
became individual organisms that then compete against organisms that are also made of
smaller beings and so forth. And I'm not saying that we are going to become one super
organism around the world, I hope that doesn't happen, because diversity is our most
entertaining aspect I think. But certainly we could become much more coordinated from
the point of view of our ultimate values. I mean everybody shares the value of wanting
their children to survive; everybody wants that. It's just that so many people don't see
past their own children. I have seen many people, for example spending immense
amounts of effort trying to figure out how to get their kid into the right preschool and
zero effort trying to preserve a planet that that kid is going to be able to live on. That is
the kind of mentality that really has to change. We have to have a longer term view.
John?
>>: When you were, I have seen models of the evolution of [inaudible] clusters and I've
seen these other galactic structure models. Do you know of anything that has tried to
model the relationship between the large-scale galactic evolution and Blavier cluster
revolution and how that fits into the whole scheme of things?
>> Joel R. Primack: Actually Blavier clusters are an interesting story. They are groups
of stars going up to about 1 million times the mass of the sun. The more typical size is
about 10 to the five times the mass of the sun that are very tight. They are only a few
light-years across. They are a few parsecs across. A parsec is 3.26 light-years. And to
appreciate how unusual that is, the distance from us to our nearest star Proxima Centauri
is about four light-years, so that distance between us and the nearest star you could have a
million stars in a globular cluster.
So globular clusters are enormously dense concentrations of stars, and because of this
density all kinds of strange things happen. You get stellar collisions. You get a
separation so that the massive stars and the massive black holes that are remnants of stars
tend to aggregate in the center. You can actually get a collapse. It is called gravithermal
catastrophe where the center collapses. It is been seen in simulations and we think that
there are examples of this.
It turns out that most of the globular clusters that ever formed probably dissociated. The
globular clusters we see today are probably a small remnant of the original globular
clusters, and the stars from those globular clusters are probably a significant fraction of
what we call the halo stars of the Milky Way. So to that extent, we try to model the
evolution of globular clusters within the galactic context, we begin to understand how
that works. The person who is probably led most of this research is Mike Fall at Space
Telescope Science Institute. I can give you more references on that.
The problem is we don't have the dynamic range in our current simulations, to
simultaneously model a few parsecs the size of the globular clusters and the multi-kilo
parsecs scale that is relevant for a galaxy, let alone the environment of that galaxy with
its dark matter halo, which is on the hundreds of thousands of parsecs scale. Currently
the best we can do with high-resolution simulations is about a factor of 10 to the fifth in
linear scale, which of course is ten to the fifth cubed in the way that we are doing the
simulation which is really three-dimensional. And the limitation is strictly because of
computer power. There is no reason in principle that we won't be able to solve this
problem in the near future.
The way we do it now is we simulate a certain scale and then the rest we regard as sub
grid physics, and we try to abstract from smaller scale simulations what the right physics
is. Smaller scale simulations and to some extent analytic calculations, and that is the way
we have been playing the game. And we keep pushing to improve the resolution of the
simulations and also the physical realism of the simulations, and that is the game that we
are up against right now. My team is one of the leading groups in the world that is doing
this along with Ofer’s dad; we work together. And there are a number of other groups in
the world that are pushing the boundaries of what we can do, and we are using the biggest
machines in the world and we are using tens of millions of CPU hours every year. We
just need bigger and better machines, and probably slightly somewhat better code.
>>: To me it's kind of interesting is that they predate the galaxy’s formation and…
>> Joel R. Primack: That was once thought to be the case but it is not now.
>>: It's not?
>> Joel R. Primack: No. In fact, the globular clusters, the oldest globular clusters--that
is an interesting story. So until 1997 there was this puzzle that the globular clusters were
thought to be older than the universe or at least older than the galaxy, and then via Parker
satellite recalibrated the distance scale because they had measured the distances
accurately for the first time. The Gaia satellite of course is going to do much better. And
what happened was the distance of the globular clusters had been overestimated by 15%
which meant that the stars are actually 30% brighter, which meant that they are about
30% younger, which meant that instead of being 16 billion years old, which wouldn't
have made sense enough in a 13.7 billion-year-old universe, there are actually only about
12 billion years old.
So there is every reason to think that the globular clusters form as part of the
phenomenon of galaxy formation, contrary to these older ideas. Sorry for going off on
that but…
>> Nancy Ellen Abrams: We would be happy to talk to anybody privately in the back. If
you would like to get a book, we would be happy to sign it. So, thank you very much.
[applause].