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An interview with Neil deGrasse Tyson

Popularizing science has become a personal passion for astrophysicist Neil deGrasse Tyson. Director of New York City's Hayden Planetarium and a monthly essayist for Natural History magazine, Tyson has also served on presidential commissions on the aerospace industry and the future of space exploration. His latest book, Origins, is a pocket history of the universe, from the Big Bang to the appearance of life on Earth.

American Scientist Online managing editor Greg Ross asked Tyson to discuss the latest riddles in cosmology, the prospects for discovering extraterrestrial life and the best ways to inspire the next generation to pursue these inquiries.

Increasingly, the study of origins seems to rely on combining insights from astronomy, geology, biology and other fields. What challenges does that pose within the scientific community, and how can we overcome them? Neil deGrasse TysonClick to Enlarge Image

The traditional branches of science that we have all come to know from high school and college are published in separate journals, and each has developed its own methods and tools of inquiry. These habits breed a lexicon in one discipline that is typically mysterious to the next discipline.

Since astrophysicists had little insight into the Big Bang without the help of particle physicists, and since chemists had little insight into the origin of the elements without nuclear astrophysicists, and since planetary geologists had little insight into how to look for life on other planets without the help of biologists, and since biologists had little insight into the environments in which extremophiles thrive without the help of geologists, and since paleontologists' view of mass extinctions was incomplete without the help of asteroid and comet specialists, we see that entire vistas of inquiry today would be impossible without a meaningful cross-pollination of disciplines.

Funding umbrellas help this cause, such as NASA's astrobiology programs, which formally bring together the astrophysicist and the biologist (and others) to inquire together about the search for life in the universe. Indeed, only after this program appeared did the search for life in the universe begin to mean something other than the search for intelligent life.

What stokes this activity today are research journals with cross-pollinated subjects like astrochemistry, astroparticle physics and, of course, astrobiology. A next generation of scientists will surely have among them people who identify their professions by these titles.

You note that most of the mass in the universe is so-called "dark matter," whose existence we can only deduce from its gravitational influence. You call this the longest-standing mystery in astronomy. Do you favor any particular explanation?

When you are a hammer, all of your problems will look like nails to you. So if you ask particle physicists what dark matter is, they will all tell you it's composed of weakly interacting supersymmetric particles.  If you ask a multiverse cosmologist, you might hear that dark matter is the gravity from ordinary matter in a parallel universe.

If you ask scientific iconoclasts, they might say our understanding of gravity is wrong and in desperate need of revision. I am personally agnostic on the "matter"—although my reading of the history of science tells me that such a long-standing problem (now going on 70 years), when solved, will likely solve other problems not imagined at the moment to be related.

You point out that we probably won't find intelligent life in our own solar system, and that interstellar distances pose great obstacles to communicating with distant planets. Does that cancel any hope of interacting with other civilizations?

If by "interact" you mean visit other stars, then there is indeed no hope: Human travel to distant solar systems lies beyond any current projection of either our technology or our science. The distances are too great, and the first rule of science research is that your experiment should not last longer than your own lifetime.

If by "interact" you mean have a  conversation, that would be difficult. With light travel times of decades to the nearest stars that resemble the Sun, one does not send radio messages with the hope of engaging in witty repartee.

For many of us, the most memorable landmark in televised cosmology was Carl Sagan's Cosmos in 1980. Did your acquaintance with Sagan influence you as you worked on the recent PBS Nova miniseries Origins?

With Carl Sagan setting the standards of science communication, my first priority was to practice how to say "bill-yun." Beyond that crucial step, I conducted the rest of the tapings knowing that the audience can detect when you are in love with a subject. And, as Carl was quick to say, "when you are in love, you want to tell the whole world."

As a planetarium director involved in outreach programs, what do you consider the most effective ways to promote appreciation of science?

Don't get in the way of children who find it natural and obvious to explore the world around them—even if it means they make a mess of your kitchen or living room. It's all about your perspective on these things. When my daughter was two and she poured her cup of milk on the dining table and watched it drizzle between the leaves, and then drip down to the floor, she was performing experiments in fluid dynamics.

Let 'em play. When you do, the kids do not have to be reintroduced to ways of questioning nature, and the task of promoting science would be a trivial exercise.

Otherwise, at least for kids ages 10 to 16, the "cool" factor is important. Is what you showed them so cool that they want to show or tell someone else about it? If so, you have succeeded in planting a seed.

Earlier this year President Bush appointed you to the "Moon, Mars and Beyond" commission, charged with making recommendations for new initiatives in human space exploration. What's the latest news there, and what are the next steps?

NASA has already begun its reorganization in response to our final report, which called for the agency to restructure itself around an exploration initiative in which the entire solar system becomes our backyard. In this way, NASA will not be specifically destination-driven. The key difference between the 1960s Apollo era and now is that NASA will pay for programs as they arise in the service of the vision. This, we hope, will create a more sustainable enterprise, with goals that can be modified en route as science and technology require or allow.

In your autobiography, The Sky Is Not the Limit, you noted the success of robotic space exploration and wrote that "We should not measure our spacefaring era by where footprints have been laid." Given the high cost and risks, why do you support a manned mission to Mars?

When I wear my scientist's hat, I do not support a manned mission to Mars. The cost versus the return on such a mission is embarrassingly low. But when I wear my public educator hat, I see and experience the public's vicarious thrills of watching their own species go into orbit and beyond. Astronauts are the only kind of celebrity I know who can have a line of people waiting for their autograph, even if the line of people does not know in advance the astronaut's name.

This level of interest runs deep and filters through Congress and on to funding streams. That's why the science programs of NASA have never been more than one-third of the agency's budget. So the social and political reality differs from how the scientific community would rather see it.

And since I spend large parts of my time at that intersection, I fully understand that urge to explore with humans and will not try to fight this basic human urge.

Cosmology still holds many unanswered questions. Which ones intrigue you most, and where do you think we'll find the answers?

My top three: What was around before the universe? Are there multiple universes? Is there a theory of everything?

String theory and related investigations in the quantum realm are hot on the trail of these questions, but I am impatient. When I started asking the string theorists nearly 20 years ago, "How much longer?" they said, "In a few more years, we are almost there!" And every two years since then, they have given me the same answer. So I do not know where to place my confidence. Einstein came up with general relativity within 10 years of special relativity. Johannes Kepler came up with his third law of planetary motion within 10 years of his first two laws. You would think legions of highly regarded string theorists could do better than 20 years. But it doesn't seem so. Maybe we are barking up the wrong tree.

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