Bruce Lahn, geneticist at the University of Chicago
Will we evolve to resist major diseases?
Sarah Tishkoff, human geneticist at the University of Pennsylvania
10,000 YEARS: HOW DO MASSIVE STARS BLOW UP?
Cole Miller, astronomer at the University of Maryland
Supernovae are rare, occurring perhaps once every several decades in a large spiral galaxy such as ours. The last time one was seen here was A.D. 1604: Johannes Kepler described it as outshining everything in the night sky but Venus. All supernovae recorded in more recent times took place in other galaxies that are millions, if not billions, of light-years away. When we finally see a supernova up close, we will be able to study it not only with ordinary telescopes but also with two new kinds of observatories—one detecting neutrinos and the other, gravitational waves—which will tell us what actually goes on inside the exploding star. If you could wait 10,000 years, you would be virtually guaranteed to get 100 or 200 of these events—enough to distinguish their subtle variations.
The explosion of a star could happen in our galaxy at any time. When it starts, the screens of computers at a handful of gravitational-wave observatories around the world will begin to flash, signaling the passage of ripples in the fabric of space. These so-called gravitational waves are a key prediction of Einstein's general theory of relativity but have so far eluded direct detection. The waves will signal that the star's core has begun to collapse under its own gravitational pull. The compressed matter turns into neutrons and releases neutrinos—particles that can zip through matter and thus escape through the star's outer layers and into space (and reach observatories on Earth). The energy released by the collapse, mostly carried by neutrinos, could blow off the outer layers of the star, making it stupendously bright. In some cases, however, the shock wave might fizzle, yielding gravitational waves but no light. We do not know for sure, because so far we have only seen the final, visible stage (with the exception of a handful of neutrinos from a supernova in 1987). Having thousands of years to observe would make all the difference. The new tools could also let us solve another open question—namely, in what conditions a dying star leaves behind a black hole or a neutron star.
100,000 YEARS: HOW DO MATERIALS DECAY?
Kristin Persson, theoretical physicist and materials scientist at Lawrence Berkeley National Laboratory
We build things all the time, but how do we know how long they will last? If we are going to build storage for nuclear waste, we need to be sure that the containers will last until the material inside is no longer dangerous. And if we are not going to fill the planet up with trash, it would help to know how much time it takes plastics and other materials to degrade.
The only way to be sure is to put these materials under stress tests for 100,000 years or so and see how they hold up. Then we could learn to build things that truly last—or that degrade in a “green” way.
We could, for example, test such materials as the copper-based alloys and glasses typically used for encasing nuclear waste. (Repositories are supposed to go deep underground in carefully chosen locations. But geologic conditions may change in unpredictable ways within a few thousand years.) Such experiments would expose the materials to accelerated wear and tear and to chemical abuse—say, varying pH. They would dial temperature up and down to simulate the cycles of day and night and of the seasons.