The 4 Percent Universe:Dark Matter, Dark Energy,and the Race to Discover the Rest of Reality

A Q&A with Richard Panek, Author of The Four Percent Universehttp://www.amazon.com/Percent-Universe-Matter-Discover-Reality/dp/0618982442
 

 
Hardcover: 320 pages
Publisher: Houghton Mifflin Harcourt; None edition (January 10, 2011)
Language: English
ISBN-10: 0618982442
ISBN-13: 978-0618982448
Product Dimensions: 9.2 x 6.3 x 1 inches
 
 
Q: What is the "four percent universe"?
 
Panek: It’s the universe we’ve always known, the one that consists of
everything we see: you, me, Earth, Sun, planets, stars, galaxies.
 
Q: What’s the other 96 percent?
 
Panek: The stuff we can’t see in any form whatsoever. At a loss for
words, astronomers have given these missing ingredients the names
"dark matter" and "dark energy."
 
Q: What are dark matter and dark energy?
 
Panek: If you find out, book yourself a flight to Stockholm.
 
Q: So nobody knows? We're not talking about "dark" as in black holes?
 
Panek: No. This is "dark" as in unknown for now and possibly forever.
 
Q: Well, then, what do astronomers mean by "dark matter"?
 
Panek: A mysterious substance that comprises about 23 percent of the universe.
 
Q: And dark energy?
 
Panek: Something even more mysterious that comprises about 73 percent
of the universe.
 
Q: Okay, 73 and 23 add up to 96 percent, which does leave a four
percent universe. But if we don’t know what dark matter and dark
energy are, how do we even know they’re there?
 
Panek: In the 1970s, astronomers observed that the motions of
galaxies, including our own Milky Way, seem to be violating the
universal law of gravitation. They’re spinning way too fast to survive
more than a single rotation, yet we know that our galaxy has gone
through dozens of rotations in its billions of years of life. Galaxies
are living fast but not dying young—a fact that makes sense only if we
say that there’s more matter out there, gravitationally holding
galaxies and even clusters of galaxies together, than we can see.
Astronomers call this substance dark matter.
 
Q: And the mysterious dark energy?
 
Panek: In the 1990s, two independent teams of astronomers set out to
discover the fate of the universe. They knew the universe was born in
a big bang and has been expanding ever since. Now they wanted to know
how much the mutual gravitation among all this matter—dark or
otherwise—was affecting the expansion of the universe. Enough to slow
it down so that the universe would eventually grind to a halt, then
collapse on itself? Or just enough that the expansion would grind to a
halt and stay there? In 1998 the two teams came to the same
conclusion: the expansion of the universe isn’t slowing down at all.
In fact, it’s speeding up. And whatever force is counteracting gravity
is what they call dark energy.
 
Q: Do astronomers have any clue as to what dark matter and dark energy might be?
 
Panek: Yes and no. As for dark matter, they think it might be one of
two subatomic particles, but physicists have been looking for these
particles for thirty years and still haven’t found them. As for dark
energy, they don’t even have an idea of what it might be. They’re
still trying to figure out how it behaves. Does it change over space
and time or not? If they can answer that question, then they can start
to worry about what dark energy is.
 
Q: If astronomers themselves don’t know what dark matter and dark
energy are, why should people believe that they exist?
 
Panek: Scientists like to quote a saying of Carl Sagan’s:
"Extraordinary claims require extraordinary evidence." Many
astronomers in the 1970s strongly resisted the idea of dark matter
until the evidence became overwhelming. And even the two teams of
astronomers that discovered the evidence for dark energy in 1998
resisted the idea until they could no longer come up with another
explanation.
 
Q: Sounds like science is a pretty straightforward process of
discovery and follow-up.
 
Panek: Straightforward, maybe. Pretty, no. As I show in The Four
Percent Universe, the discoveries involved a lot of behind-the-scenes
rivalries that sometimes turned ugly—rivalries that continue to this
day. But in a way, these rivalries have been good for the science.
When scientists who would like nothing more than to prove one another
wrong wind up agreeing on a weird result, their peers can’t help but
take the result seriously. Astronomers hate to say it—they’re as
superstitious as anyone else, and they think they’ll jinx their
chances—but there are Nobel Prizes at stake here.
 
Q: So this is real. Astronomers actually believe that 96 percent of
the universe is "missing"?
 
Panek: Yes. They call it the ultimate Copernican revolution. Not only
are we not at the center of the universe, we’re not even made of the
same stuff as the vast majority of the universe.
 
Q: What now?
 
Panek: Nobody knows! And for astronomers, that’s the exciting part.
Again and again, at conference after conference and in interview after
interview, I’ve heard astronomers say that they can’t believe how
fortunate they are to be scientists at this point in history. Four
hundred years ago, Galileo turned a telescope to the night sky and
discovered that there’s more out there than the five planets and
couple of thousand stars that meet the eye. Now astronomers are saying
that there’s more out there, period—whether it meets the eye or not.
Lots more: the vast majority of the universe, in fact.
 
Q: If this revolution is such a big deal, why haven’t we heard about it?
 
Panek: Because it’s just beginning. Only in the past ten years have
scientists reached a consensus that what we’ve always thought was the
universe is really only four percent of it. Now they feel that
figuring out the missing 96 percent is the most important problem in
science.
 
Q: Will finding answers make our lives better? What’s the payoff?
 
Panek: On an immediate, day-to-day, price-of-milk level, nothing. But
Galileo’s observations starting in 1609 completely changed the physics
and philosophy of the next four hundred years in ways nobody could
have anticipated. As I argue in The Four Percent Universe, this new
revolution is going to have the same kind of effect on civilization.
The fun is just beginning.