Space has a new meaning.

The accepted model of cosmology, which had heretofore assumed that space was actually empty - that Einstein’s cosmological constant was indeed zero - has been superseded, thanks to Lawrence Krauss.

In Krauss’ bizarre replacement the cosmological constant is non-zero, meaning the energy density of the universe today may be dominated by empty space.

During the 1980s cosmologists developed what looked like a beautiful model for cosmology, based on fundamental ideas from particle physics which appeared to agree with the wealth of emerging observational data.

The news then was exciting. Central to the 1980s model was the notion that the Universe is exactly "flat", in the sense that the ratio between the density of matter in the Universe, which works to slow its present expansion down, and the current expansion rate, are exactly matched so that the Universe will expand forever, slowing down, but never quite stopping.

"Geometrically, this meant the curvature of space on large scales is precisely zero," says Krauss, the Ambrose Swaney Professor of Physics at Case Western Reserve University in Cleveland.

"Now, a decade later, we are beginning to have overwhelming evidence that there simply isn't enough matter in the Universe to make this happen," he says.

About four years ago, Krauss and colleague Michael Turner, the Rauner Distinguished Service Professor and chair of the Department of Astronomy and Astrophysics at the University of Chicago, argued that even a stranger possibility was suggested by the data. They proposed that in fact the Universe was flat, but the missing extra density was provided by the energy associated with empty space.

The peculiar notion that empty space might govern the nature of an expanding Universe was first proposed, in a different context, by Albert Einstein in 1917, but he quickly discarded the idea when it became clear it wasn't necessary to reconcile observations and theory at that time.

Since then, the best value for the cosmological constant was assumed to be zero, since no measurement indicated the contrary.

Recent observations of the expansion rate of the Universe now lend much stronger support to the notion that it is not zero, and is precisely in the range Krauss and Turner argued it should be on the basis of other observations. Even a very small pressure can be important if it permeates the entire Universe.

"Explaining why empty space has energy, and why it should have an energy that is comparable to the present energy density associated with matter in the Universe is currently well beyond our understanding, which makes this one of the most interesting developments in cosmology in the past 20 years," Krauss says.

Krauss is drawn to interesting science like moons are drawn to major planets. It’s what makes him glow.

Krauss, who has a loquacious gift good for generating public interest in science, is not content merely continuing what Einstein started. He’s intent now on resuming the work of the late Carl Sagan.

Krauss, already the author of five popular books, among them The Physics of Star Trek (Harper Perennial, 1996), and Beyond Star Trek (Basic Books, 1997), has a talent for amusing readers with lively discussions of theoretical physics. He does this by enshrouding the more arcane topics of physics in entertaining questions, addressing issues such as what happens when the transporter beams you off the bridge of the Starship Enterprise, what anti-matter is and what starships do with it, how a hologram differs from a holodeck, and exactly what gets warped at warp speed.

Science fiction, Krauss has found, is useful in teaching physics to those who might otherwise be uninterested. Tending more toward Hawaiian shirts than academic tweed in his writing style, Krauss provides new approaches for the unconversant to such topics of popular interest as the potential for the existence of life elsewhere in the Universe, the possibility of intergalactic space travel, the nature of the quantum universe and what it would take for extrasensory perception to really exist.

The books became bestsellers, interesting a broader audience than the Trekkie subculture. Beyond Star Trek, for example, sold over 120,000 copies in hardcover, a record for its publisher. Another, Fear of Physics (Basic Books, 1993), was printed in eight languages and was the 1994 finalist for the American Physical Society's Science Writing Award.

The New York-born, Canada-raised Krauss is equally comfortable lecturing undergraduates on physics and astronomy, speaking at the Yale Club, delivering the opening plenary lecture in French at the biannual French Physical Society, addressing a room full of Klingons or chatting on the tranquil couches of Good Morning America. His campaign has taken him several times recently to Kansas, to counter the creationism movement by attempting to inject reason into the resurgent nescient zealotry there intent on cumbering the state’s public school system.

All of which have helped establish the ebullient Krauss as the heir-apparent to Sagan’s crown of Popular Champion of Science.

The kinetic Krauss, a fan of Plutarch, Portnoy, Chomsky, the Beatles, Sartre, Woody Allen, and the Marx Brothers, has a mind possessed of equal parts eclectic, protean intelligence and crisp, playful wit. He’s fond of saying "I like to keep my mind open, but not so open my brains fall out".

His persistence and popularity recently earned him the 1999-2000 Public Understanding of Science and Technology Award from the American Association for the Advancement of Science, the world's largest interdisciplinary science organization.

"Lawrence Krauss has become a much-needed successor to Carl Sagan," says 1979 Nobel Laureate Sheldon Glashow, the Higgins Professor of Physics at Harvard University. "He’s an inspiration to our scientifically-inclined youth, a gifted advocate of scientific literacy for all citizens, a demystifier of science, and its staunch defender as a force for good."

That the Universe is comprehensible at all continues to amaze Krauss, 45, who received his Ph.D. from MIT, and was a Fellow at Harvard before, first, joining the physics and astronomy faculty at Yale, then Case Western Reserve.

"Who would have thought that we, a sentient species, living in a remote corner of a mediocre galaxy, would be able, by a series of observations made without having left our own solar system, to uncover so many mysteries of creation?" he asks rhetorically. "That we can predict with confidence the results of processes that occurred in the first second after the big bang, when the Universe was over 10 billion degrees in temperature, and that our predictions agree with observations, is remarkable."

Krauss’ love of science started in his formative years, reading popular books by and about scientists such as Einstein, Gamov and Asimov.

"It got me excited," says Krauss, whose parents, Fred and Geraldine Krauss, operated a gift shop. "Those books are one of the reasons I now write popular books myself, hoping to excite young people."

His mother, who wanted him to become a medical doctor, encouraged his early interest in science, but unfortunately this gave him the impression that doctors were scientists. "By the time I found out they weren't, I was hooked on science," he says. "This is not to say, however, that it was clear to me that I would choose a career in science. I enjoyed history very much, for example, and worked on a history book as an undergraduate. But throughout I retained an interest in fundamental questions about the universe. The notion of unraveling the secrets of nature really turned me on."

The same awe that drove Sagan now drives the garrulous Krauss, who relishes the idea of succeeding Sagan. Sagan helped carry on an important tradition in science, and Krauss likewise believes scientists have a responsibility to explain what they do to the public, for three reasons.

"One, the public pays for our research; two, we cannot expect people to support our work if they do not appreciate it; and three, science plays such an important role in the development of our technological society that it is both extremely sad and dangerous for the public to be scientifically illiterate. I think that my efforts at popularization, while they do take time away from my research, are among the most useful things I do," says Krauss. "And frankly, since I seem to be able to do it successfully, I think I have a responsibility to continue these efforts."

Krauss says the demands on him have grown so great he has begun to guard his time more jealously.

"I share my time between running the physics department, initiating new programs, hiring faculty, fending off administrative offers here and at other universities, working on research problems with postdocs and students, writing my books, and lecturing publicly as well as doing a lot of TV and radio," says Krauss.

It helps that his wife, Kate, and their 15 year old daughter Lillian, understand the demands of serving many masters. It also helps that he tends to work well doing several things at once, and that he requires little sleep.

His current schedule illustrates the pace of his life and the scope of his talent. Right now he is working on four research projects on issues associated with cosmology, including such items as the cosmological constant and the origin of matter in the universe; three books, including a new popular book, titled Genesis, The Lives of an Atom; a college-level introductory textbook on physics for non-science students; a new edition of an old book he wrote on dark matter; and two TV series, one based on the Genesis book, and another potentially associated with The Physics of Star Trek.

Then there are the lectures, which average two to four every month somewhere around the country, to which he brings the soul of a fanatic and the energy of an entertainer. Since 1996, Krauss has given more than 300 lectures and media interviews. He is a regular contributor to the op-ed pages of the New York Times, including one article he faxed at 3 a.m. following NBC's sappy broadcast early last year of "Confirmation: The Hard Evidence of Aliens Among Us".

The fun-loving Krauss believes you have to do whatever you can to make people interested, which frequently involves a little song, a little dance, a little seltzer down your pants. He shares his office, already choking with books and promotional materials, with two life-size cutouts of Capt. James Kirk and Science Officer Spock.

His enthusiasm for science never dwindles. The wonder of it vibrates inside him like an instinct seeking its source. It still tickles him that we can predict what it’s like inside a star that’s exploding - when a region the size of the Sun shrinks to the size of Manhattan in a few seconds, and that our predictions are verified when we observe obscure particles called neutrinos coming from the other side of the galaxy.

"These kinds of wonderful aspects of our intelligence should not be ignored," he says. "I am continually amazed by the fact that the observable Universe, covering at present over 20 orders of magnitude in scale, can be explained by a handful of equations, in such a way that physicists who study one set of phenomena, can make themselves understood by physicists who study remote areas. Why the same notions re-occur throughout nature is perhaps something of a mystery."

Uncovering these hidden connections is part of what continues to make physics exciting to Krauss. To him, the most interesting ideas humans have yet devised are scientific in nature, and it troubles him that universities tend to require students to read great literature in order to expose them to great ideas.

"I’m saddened that we don't appreciate the cultural importance of the great ideas associated with scientific discovery," he says. "In some sense, Einstein's remarkable ideas about space and time have filtered down to popular culture, but the vast majority of the insights we have about the universe haven't. I firmly believe that if people were properly exposed to this wealth of ideas, they would be as turned on as I am.

"Even relatively simple ideas, like Energy, have changed the way we live. In fact, I would argue that the concept of energy was a more important development, from the point of view of human civilization, than any of the profound ideas associated with political philosophy in the 18th and 19th centuries," he says. 

Krauss most admires people who work hard, and who are honest with themselves about themselves. "I have been blessed with many remarkable collaborators, and perhaps Frank Wilczek, a physicist, stands out because of his pure interest in knowledge," he says. "Generally, Richard Feynman is a strong role model, both because of his no nonsense attitude, and his continual desire to have fun with physics and life. I admire Noam Chomsky, because of his intellectual honesty about unpopular issues. I also admire people who are more selfless than we physicists, or academics in general. After all, we get paid to do exactly what we want."

What Krauss is doing is exposing the lay world to the same infectious enthusiasm for science for which Carl Sagan was once best known. Sagan’s trademark turtle necks, elbow patches and "billions and billions" may be gone but his fervor for science remains, passed to Lawrence Krauss.

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