Elephants. Pyramids. Trips to the moon. People used to think of big things as important, denigrating the small. But midway in the 20th century, that changed.

"Nowadays small is big. This is the century of small," said Paul McEuen, Cornell's Goldwin Smith Professor of Physics, in a Cornell Summer Events lecture "The Future of Small" in Kennedy Hall July 6.

Since most people are not good at conceptualizing things at the nano scale, McEuen offered this comparison: Earth is 10⁷ meters across; people are 1 meter across, a ratio of 10^-7. In electronics, the ratio of a computer wafer to its smallest component, a computer chip of 100 nanometers (one nanometer is a billionth of a meter), is also 10^-7. "Packed onto a computer wafer is a density of stuff the equivalent of the entire planet," he said.

A time version of this miniaturization has progressed along with the spatial miniaturization, explained McEuen. A person can think one thought per second; a computer "thinks" at the scale of a nanosecond, a billion thoughts for each one of ours. Assuming a person is thinking about half the time, it would take someone 70 years of thinking to equal one second of computer processing.

But life can build things far more compact than anything we can yet achieve. We can create a chip that's 100 nanometers, but a virus the same size can pack 10⁵ bits of information into the same space and is smart enough to kill you, said McEuen. "It would take a 50-year program at least until we can build something from scratch that begins to rival that complexity."

McEuen described the current revolution in synthetic biology as "hacking life." Once DNA has been sequenced, scientists can modify it or synthesize it from scratch, producing a life form with a different genome from the original. McEuen offered the light-hearted example of the CalTech scientist who created DNA origami: DNA strands that assembled themselves into happy faces.

But synthetic biology offers huge risks: bioterrorism, political destabilization, ecological catastrophe. As a reference, McEuen noted that in four years of fighting, 16 million people were killed in World War I. It only took months for the 1918 influenza to kill more than 50 million.

Still, the field of synthetic biology could also offer huge benefits, like biofuel from algae and malaria drugs cheap enough to use in the third world. Many large companies are interested in turning DNA into cash, said McEuen, but added that the science is very democratic. "There's a gold rush going on. Do-it-yourself synthetic bio labs are popping up in garages all over."

The very small just may be the solution to the very large energy crisis. In a "solar energy smackdown," McEuen demonstrated that nanotechnology wins over synthetic biology: silicon chips are 10 percent efficient, compared with biofuels, which are 1-2 percent efficient. "And corn to ethanol is only 0.1 percent efficient," he added. "Ethanol is strictly politics, not science."

But while we wait for nanotechnology to provide solutions, McEuen concluded, "We could reduce our energy needs by a factor of two just by making minimal lifestyle adjustments." If everyone switched from the 5 percent efficiency of incandescent light bulbs to the 50 percent efficiency of LEDs, for example, the energy saved would approximate the annual energy production of 50 nuclear reactors.

How many people does it take to change a light bulb? McEuen asked. "It takes all of you."

Linda B. Glaser is staff writer for the College of Arts and Sciences.