Part one of a
two-part series.
Dark
matter, dark energy, and the Big Bang are ideas so large and seemingly
intangible it’s not easy to get a grip on them. Adam Frank, associate professor
of physics and astronomy, theoretical astrophysics, and plasma physics at the
University of Rochester, wrestles with concepts like these every day. Despite
the complicated nature of his work, he manages to describe it in compelling and
understandable prose in articles for Discover and Astronomy magazines.
           Frank, who lives in Rochester with
his wife, Holly Merrill, and his two children, Sadie and Harrison, has managed
to retain the sense of excitement, awe, and wonder that he had as a child, when
his father took him to the Hayden Planetarium in Manhattan. In fact, he could
have told you then what he’d be doing today.
           “I never really had any choice,”
Frank says. “The earliest memory I have is when I was 5 years old. My dad had a
big library and he had amazing science fiction magazines — Isaac Asimov, etc.
— and they always had cover paintings on them of guys bouncing around on
Jupiter or something. Those were so cool.”
           We recently sat down with Frank to
try to get an understanding of the latest breakthroughs in astrophysics. Along
the way our conversation touched upon art, philosophy, and the theory of
everything. The following is an edited version of our interview.
City:We’re here at a big university, in a fairly
large city, on a big continent, on a huge planet, in what seems like an
enormous solar system. You take it from there.
           Frank: It’s hard to explain how small we really are. Nothing in our day-to-day
activities gives us a sense of the vastness or emptiness of space. We are orbiting around
a small star; there are nine planets that we know of. The solar system, by our
scale, is quite large. We sent the Voyager probes out in 1977. They’ve been
traveling 25 years; they’ve just now gotten to the edge of the solar system.
But our solar system is barely our backyard. The distance to the nearest star
is probably about 10,000 times farther than the distance to the edge of the
solar system. That’s our next-door neighbor. The Milky Way galaxy, our local
city of stars, has a hundred-billion stars and is about 100 million times
larger than the size of the solar system.
           City:And there are many more galaxies.
           Frank: Yes, virtually uncountable galaxies. When we look in the sky we see hundreds of
millions of galaxies, each one with hundreds of millions of stars. Â Â Â Â City:Humans have been looking at the sky for
millennia and seeing heavens or constellations created by connecting the dots.
Give me a brief history of our perception of the stars.
           Frank: A thousand
years ago we thought there were five planets; we didn’t know about Uranus,
Neptune, and Pluto. Then we thought the stars were on a bowl or a sphere out at
some distance not too far. It wasn’t until telescopes got better in the 1800s
that we really got a sense of how big the universe was. Even 100 years ago, we
weren’t sure there were other galaxies.
           It was just 500 years ago that the
Polish astronomer Copernicus showed us that the earth was not the center of the
solar system. That was a huge conceptual shift displacing us from being at the
center of the universe. Suddenly it was the earth going around the sun. And of
course it must follow that the earth must not be very important, because all
the planets go around the sun.
           Later we realized that the sun
wasn’t at the center of the universe, but just one star in these uncountable
numbers of stars in the galaxy. Then we learned that the galaxy wasn’t the
center of the universe, but just one of an unmeasurable number of galaxies.
Part of our education as a species over the last 100 years has been our
understanding that we’re nothing special, at least in terms of location in the
universe.
City:What’s the latest theory on the composition
of the universe?
           Frank: Recently,
something very funky has happened. Over the last 50 years we’ve come to
understand that when we look out at the night sky and see all those bright
shiny lights, and when we look through telescopes and see distant glowing
galaxies, we’re only seeing a small fraction of the stuff that’s out there.
           There has been a discovery of what
is called dark matter — matter that we can’t see directly, but we can see its
influence through gravity. We see galaxies spinning and we can measure how fast
they’re spinning. There’s a direct relation between how fast they’re rotating
and how much mass is in them. What we find is that they’re spinning way too
fast for the amount of glowing stuff, so it has to be that there’s a huge
amount of stuff around the galaxy that is invisible to us.
           City:I’ve read that what we see or know of is
only about 27 percent visible matter and the rest is dark matter or dark
energy.
           Frank: It’s actually
worse than that. Luminous matter, the kind of matter that we’re made out of —
our hands, computers, books, everything we can even imagine touching — makes
up only about five percent of the universe. The majority of matter is dark
matter. Now we have also discovered a kind of dark energy too, through
observations of stars exploding in very distant galaxies.
           City:The Hubble Space Telescope acts as a time
machine, because of the time it takes for the light to reach us.
           Frank: Yes, the
farther out you look in space, the farther back you’re looking in time. We’re
now able to see back very close to when the universe was born with the Big
Bang. We thought it was like an explosion: things get flung out and they’re
coasting. Now we realize they’re not coasting, they’re accelerating. There was
the Big Bang and then some kind of energy pushing things farther and farther
away from each other.
So it’s taking this Copernican idea and
pushing it to the limit. Notonly is
the universe vast and we’re not significant because it’s so big and we’re just
a little tiny planet going around a little tiny star, but actually our kind of
matter is not even the important part if you add it up. We’re kind of an
afterthought. It’s like there’s this amazing landscape and all the things we
can see are just the Christmas lights strung on top of the landscape.
           City:And yet, look at the complexity of each of
us. Leonardo da Vinci believed the human body was a microcosm of the earth in
terms of the way liquid nurtures an intricate system. Now that we know about
the multiplication of cells, brain waves, etc., could a case be made that the
human body is more of a microcosm of the cosmos?
           Frank: We’re so
incredibly complex; we’re sort of everything and nothing at the same time. We
are insignificant in a tiny part of the universe that is insignificant, but, on
the other hand, what we think we understand about dark matter is that it
doesn’t clump. You can’t get a dark planet or a dark tree. The most complex
structures you can form are big fluffy halos that stretch across tens of
thousands of light-years. You can never get it to coalesce into anything like a
rock.
           So most of the stuff in the
universe, the dark matter and dark energy, will never form structures like
planets. But our kind of matter can form this amazing complexity through the
organization of biological molecules. With our kind of matter you can get this
enormous capacity for organization — trees and birds and life, essentially.
So we may be incredibly significant.
City:Is the earth and all of its life simply a
fluke?
           Frank: There are a
couple of different frontiers in astronomy right now. One is cosmology; we
actually have the ability now to gain quite a bit of understanding about how
the universe was born, and that includes dark matter because we can see its
influence.
           The other frontier is star and
planet formation. In 1996, for the first time, we had really clear evidence
that a star much like the sun had other planets going around it. That was a
revolution. That question has been around for at least 3,000 years. Giordano
Bruno, a famous heretic around the time of Galileo, was burned at the stake
because, among other things, he believed there were other planets orbiting
stars; the earth was not unique.
           City:The Pope recently declared that Galileo was
not a heretic.
           Frank: [laughs] Yes,
it took a little while but they finally got around to it. Astronomy can be very
contentious, very dangerous. This idea of other planets, or the “many worlds”
hypothesis, has been around a long time. It’s amazing that in our lifetime we
have seen this question answered. Since 1996 we have been discovering,
indirectly, planets going around other stars. We can see the star wobble back
and forth as the planet goes around it.
           City:How much closer does this get us to finding
life out there?
           Frank: This
discovery is huge; it takes the first step because you’re going to need a
planet to have life form. We have now found about 100 stars that have planets
orbiting them. That means we can start to do a census of these planets. Looking
at our solar system, it looks like life only formed on earth. It may have formed
on Mars; Mars at least had the right conditions. But there are “habitable
zones” around a star, a region where liquid water can exist. So there’s only a
range of places you can put a planet to have the possibility of life forming.
           There’s an interesting book, Rare Earth, by two University of
Washington researchers who came up with the hypothesis that microbes
[microscopic life forms] are probably all over the place. It’s probably easy to
get microbial life forms to occur, to evolve. The earth was formed five billion
years ago and the first signs of life seem to occur about four billion years
ago. So it didn’t take very long for life to get started. But for the next
three billion years it’s just microbes. There’s no more significant evolution.
           Then, in a very short span, for
reasons we don’t understand, something happens — the Cambrian explosion —
where suddenly you get all these diverse life forms evolving. That was a hint
that microbes might be easy to get but animal life forms — multi-cellular, evolved,
complex life forms — that may be difficult to evolve, so it’s very hard to
say. Are we the only life in the universe? You look at all the planets and all
the stars and you think there’s got to be others out there. That’s what I
believe. On the other hand, if it’s a one-in-a-trillion chance of having all
the accidents you need to get life to occur, and you’ve only got a trillion
planets, then you’ve run out of luck.
           City:When it was discovered a few years ago
that there may have been microbes on Mars, people theorized that life on earth
might have come from an asteroid.
           Frank: Yes, there’s
still a lot of discussion about that. Microbes could be very hardy. We know
that microbes can live deep in rocks and we know that when asteroids hit Mars,
rocks from Mars were blown over to the earth.
           City:What are the chances of finding highly
evolved life?
           Frank: The issue of
intelligence is another difficult one. Is intelligence selected for in
evolution? We always think that’s what happens; evolution always leads to
intelligence. But there’s no evidence that what we call intelligence is
necessarily the end product of evolution. Given our own history — we haven’t
been on the planet all that long and we do a lot of stupid things — it’s
possible we may not last that long.
           I certainly believe that the
universe is full of civilizations, because I want to believe it. That would be
really cool. But from the scientific point of view, I don’t have a whole lot of
evidence. What’s cool now is we’re on the verge of being able to answer that
question. NASA is designing telescopes called the Terrestrial Planet Finder
that should be able to see if there are earth-like planets around other stars.
           If we can take a “spectra,” meaning
take the light and break it up into its component pieces, we could be able to
detect things like methane. You have to have life to have certain chemicals
present in the atmosphere. In 10 or 20 years, we can’t go visit, but we may
have some strong evidence for the fact that there are planets that have life on
them.
           City:Will the Hubble eventually allow us to
witness the Big Bang?
           Frank: With the
Hubble we can’t see back to the Big Bang because there’s no light from the Big
Bang that it can tune into. The Hubble can take us back to around a billion
years after the Big Bang. If you look far enough back, the things that are
emitting light haven’t formed yet.
           Bob Williams, the former director of
the Hubble, did a cool thing about 10 years ago. He pointed it at a region of
sky that didn’t have much in it and left the shutter open. The image he and
others made is called the Hubble Deep Field, and it’s one of the most famous
pictures the telescope took. That representative little piece of sky turned out
to be full of very old galaxies. What we are seeing in the Hubble Deep Field
are galaxies in the epoch they were being put together.
City:Here are two unanswerable questions: What
was before the Big Bang? And how does something come from nothing?
           Frank: On a certain
level, the question of what was before the Big Bang is not amenable to the
methods of science, which doesn’t mean we suddenly jump into the realm of
religion or spirituality. One of the things that is beautiful about what we
have come to understand about the universe is that we have a kind of blinders
on that came from evolution. We experience the world through three-dimensional
space and then there’s this fourth dimension of time. One thing we’re realizing
is that there may be a lot more dimensions than that; we just can’t perceive
them. That doesn’t mean they’re not there.
           So this question of beginnings and
endings — people ask what’s at the end of the universe, do you come to a
brick wall? — can only make sense if you’re thinking of space being this big
shoebox into which all the stars were poured and there has to be an edge. What
we’ve learned is, if you start thinking in higher dimensions — like the games
Picasso and the cubists were playing in paintings like Les Demoiselles d’Avignon, where you see all the sides of a woman’s
face at once — once we recognize the potential for there to be more than
three dimensions, suddenly, literally, you’re no longer boxed in.
           City:How can there be more than three dimensions?
           Frank: We see each
other, and what we see are three-dimensional shadows of four-dimensional
creatures in the sense that we exist in time as well. This is what Einstein
recognized. When you walk under a lamppost, first your shadow is long. Then,
when you get under it, your shadow gets short, then long again. That shadow is
a two-dimensional representation of what is really a four-dimensional creature.
           There’s an example of how things can
be so different going from low to high dimensions. Once we allow for the
possibility that the universe might have 10 dimensions a lot of things change.
The question of what came before the Big Bang may be something that science can
never answer. Our ability to measure anything — and that’s what science is
about, if you can’t measure it, it’s not part of science — may stop at the Big
Bang. But it’s also possible that we may find ways in which things can kind of
wrap back on themselves. The surface of a sphere doesn’t have a beginning or an
end.
           City:Just as the earth has no beginning or end,
it strikes me that the universe, in an inverted sort of way, would also have no
beginning or end.
           Frank: It’s
possible. One thing we’ve been doing since Einstein is thinking about the
geometry of the universe in more than three dimensions. So it either lies at
the edge of what our scientific understanding can tell about the world, or it’s
possible that when we add the possibility of extra dimensions, it will allow us
to find ways in which the universe need not have a boundary in time. We know it
doesn’t have to have a boundary in space.
City:You alluded to Picasso. When I think of an
astrophysicist crunching numbers, constructing computer models, or coming up
with theories, it seems similar to an abstract art. Do you see a connection?
           Frank: Both art and
science require an attention to detail and a reverence. Both ask of the
practitioner an openness and a position of creativity, trying to take what is
experienced someplace it hasn’t been before. I try to beat out of my students
the idea that science is this giant, picking up facts, putting them in its bag.
Nothing can be further from the truth. The funny thing about science is the end
product often has a highly dispassionate, impersonal view. I can’t put a joke
in a scientific paper. And even if I write alone, I say “we” carried out this
experiment.
           But in doing science, you get passionate about it. I’m a theoretical
physicist; I don’t look through telescopes. There’s a beauty to mathematics
that is beyond words, a rapture that comes from the consideration of the way
things fit together. I often think of mathematics, which is at the heart of all
science, as being very much a poetic language. With poetry, one metaphor can
embrace a whole set of nuances and subtleties in the same way that the equation
for an ellipse has every possible ellipse in it.
           Art and science are very similar.
When I took Shakespeare in college the professor asked why we were taking this
class. I wrote, “I know why Einstein is great, but what makes Shakespeare
great?” When I left I knew why. It’s 500 years later and the stuff Shakespeare
wrote is so true. That’s why I love Joseph Campbell, his idea that myths carry
from one culture to another, whether you’re a tribesperson 5,000 years ago or a
city dweller today. In science, the laws of physics are true anywhere in the
universe.
           City:Your particular field of study is Planetary
Nebulae.
           Frank: I study how
stars are born and how they die. At the beginning and end states of their lives
they tend to be surrounded by enormous clouds of gas either because they’ve
blown them out or they’re forming out of them. So I study what are called
gas-dynamical processes. Each Planetary Nebula is a sun-like star at the end of
its lifetime. These dying stars blow out incredible sculptures light years
across. They’re just beautiful. I use the equations of mathematical physics to
try and understand why they have that shape and what it’s telling us about how
a star dies.
Next week:
Adam Frank discusses the possibility of multiple universes, the theory of
everything, and the joys of being a café astrophysicist.
This article appears in Jan 29 – Feb 4, 2003.
