Scientist explores truth, beauty in the expanding universe

Photo by Neil Brake

Astronomer Mario Livio delivered the 2001 Seyfert Lecture last week. Livio is the head of the science division of the Space Telescope Science Institute, which operates the Hubble Telescope.

By David F. Salisbury

Usually, scientists are pretty pragmatic. When talking about their work, they tend to emphasize how well it explains the way in which a system works and how well it can predict what that system will do in a given set of circumstances.

Yet, there is an underlying aesthetics to science. This is not discussed as often, but Mario Livio, this year's Seyfert lecturer, addressed this topic head-on in his public lecture last Wednesday night, Jan. 24.

Livio heads the science division at the Space Telescope Science Institute that operates the Hubble Space Telescope and is a self-professed art fanatic. The title of his presentation was "Beauty and the Accelerating Universe." His talk was based on his popular book, The Accelerating Universe: Infinite Expansion, the Cosmological Constant, and the Beauty of the Cosmos.

The astronomer began by trying to define beauty, through dictionary definitions and examples from paintings ranging from Vermeer to Picasso. Then he projected a series of beautiful photos from the Hubble telescope, but explained that this was not the sort of beauty he wished to discuss.

Acknowledging that the subject was more abstract than the examples he had given, Livio said, "I want to discuss when a scientific theory is beautiful." Then he introduced his theory of beautiful theories. To be beautiful, he maintained, a theory must possess three characteristics: symmetry, simplicity, and the Copernican principle.

He then discussed two kinds of symmetry: symmetry of translation and rotation. Translational symmetry means something that doesn't change when moved along a straight line. Rotational symmetry means that something does not change when spun in a circle. Livio, however, was not concerned with the symmetry of objects, such as the right-left symmetry of the face, but with the symmetry of the basic laws of physics.

"Symmetry of the laws of physics means that the laws don't change from one place to another," Livio said. "Because of this, we can apply the same laws to DNA or to a galaxy."

The difference between symmetry of the underlying laws of physics and that of objects themselves is a fairly modern concept. Even Galileo didn't quite grasp the difference because he was extremely upset when Kepler reported that the orbit of the planets was elliptical, rather than circular, he explained.

Striving for simplicity is part of the basic reductionism in science: the effort to replace many questions with a much smaller number of questions. The desire for simplicity in scientific theories has much in common with the desire to believe in an omnipotent God who is responsible for everything, he said.

Projecting a simple triangle and then adding smaller triangles to the mid-points of each of its sides and then adding smaller triangles to the mid-points of all the sides of the resulting figure, and so on, Livio created an object that looked much like a snow-flake. "Not only is the snowflake beautiful, but there is also beauty in the fact that it can be created by a process so simple that I can explain it to a four-year-old," he said.

Livio used the paintings of Mondrian to illustrate how modern artists have followed a path that in some ways parallels what has occurred in modern science. He showed how Mondrian began painting trees in a representational way, but then got increasingly abstract as the artist looked beyond the surface and began painting underlying shapes and relationships. Finally, he used one of Mondrian's later paintings that consists entirely of straight, multi-colored ribbons. The painting's title is "Broadway Boogie Woogie."

"Can't you see how he captured the lights and activity of Broadway?" he asked.

The Copernican principle is quite a bit different from symmetry or simplicity. It is the principle that humans are nothing special, Livio said. It was first established when Copernicus proved that the Earth was not at the center of the solar system. It was further reinforced with the discovery that the solar system is not at the center of the galaxy and that the universe is filled with millions of other galaxies.

The astronomer then discussed the evidence that the universe is expanding: it provides a simple explanation for the fact that virtually all the other galaxies in the universe are moving away from our Milky Way galaxy and the farther away they are, the faster they are receding. By turning the clock back, scientists have calculated that the universe began from a single point about 14 billion years ago. This has been dubbed the "Hot Big Bang."

Physicists have identified four basic forces. Two are familiar: gravity and electromagnetism. Two are unfamiliar: the strong force that binds the nucleus of the atom together and the weak force that is responsible for radioactivity.

"Why are there four forces, not just one?" A single force would mean that everything is the same, so the universe would be very boring, he pointed out. The Big Bang theory, however, has allowed cosmologists to have their simplicity and complexity at the same time. In the microseconds after the universe formed, there was only one force, they theorize. But as the universe began to expand, it also began to cool. Much like a liquid has the same properties in all directions, but, after it freezes, the resulting crystal has different properties in different directions, scientists think that the single force broke down into the four forces as part of the cooling process, Livio said.

Everything had been going beautifully in the realm of cosmological theorizing, Livio said, until 1998 when the first reports came in that the universe was not only expanding, but the rate of expansion is increasing. For a number of years, astronomers have been attempting to predict the ultimate fate of the universe. They argue that the force of gravity is continually working to slow down the universe's expansion. So if the universe contains enough mass, then the rate of expansion will ultimately slow down and stop. If it contains more than enough mass, it will then begin shrinking back on itself until it ends in a "Big Crunch" that recreates the "Big Bang."

The beautiful solution in this case is if the universe has just enough mass to balance the universe's expansion, Livio argued. Unfortunately, the additional measurements that have been made since 1998 tend to back the initial study, he reported.

"I would put the odds that this is right at about 50-50," Livio said. "But, if the universe is accelerating, that's it!"