As a visiting scientist at the Solomon Schechter Day School of Bergen County last week, Mario Livio clearly enjoyed fielding questions from little questioners.
In his day job as astrophysicist, he wrestles with some of the biggest questions in science.
In a paper published a month ago, he speculated on what planetary conditions are necessary in a solar system to support life.
In particular, he showed that while the asteroid belt proved fatal to dinosaurs – wiped out by an asteroid collision 65 million years ago – in an earlier era of the earth’s history those collisions brought the planet the water that was needed for life to evolve.
That is because the asteroid belt is at the “snow line” – the region where water is far enough from the sun to remain intact as ice.
But our asteroid belt, he discovered, is a specific result of Jupiter’s position in the solar system. Were it absent or more distant from the sun, his computer models showed, the rocks and water that constitute the asteroid belt would have coalesced into a planet.
“To have such ideal conditions you need a giant planet like Jupiter that is just outside the asteroid belt [and] that migrated a little bit, but not through the belt,” Livio explained in a NASA press release. “If a large planet like Jupiter migrates through the belt, it would scatter the material. If, on the other hand, a large planet did not migrate at all, that, too, is not good because the asteroid belt would be too massive. There would be so much bombardment from asteroids that life may never evolve.”
Looking through a database of 520 giant planets detected in recent years around other stars, he and his colleague Rebecca Martin discovered that only 19 were far enough from their sun to allow formation of an asteroid belt.
That may seem like a small amount.
“But four percent is a lot,” he said, explaining his finding to faculty members at Solomon Schechter. “There are billions of stars in the Milky Way galaxy alone.”
The question of whether there is extraterrestrial life is not, however, the truly big question that occupies Livio’s mind.
That question concerns what Livio said was the Hubble telescope’s most important discovery.
“You may have heard that since the 1920s we’ve known than our universe is expanding,” Livio told the Schechter students.
“Until about 1998, we thought this expansion would slow down.
“Why did we think that? For the same reason that if I take my keys and thrown them up” – he demonstrated just that – “they slow down and eventually reverse their motion and come back. Because of gravity. The earth has gravity and pulls on the keys and slows it down. So we thought that all the mass in the universe would slow down the expansion.
“Instead, what we discovered in 1998″ – by measuring the light of distant galaxies – “is that this expansion is speeding up. It’s accelerating. It’s like I would take these keys, throw them up, and instead of slowing down, they would speed up. There must be something that is pushing on it,” he said.
That force “is a property of space itself.” It is called “dark energy.”
But what it really is – and why it is – remains unknown.
It became the subject of his first book, “The Accelerating Universe: Infinite Expansion, the Cosmological Constant, and the Beauty of the Cosmos.”
He has also written about mathematics. “Is God a Mathematician?” published in 2009 examines the philosophical question of how and why the abstract ideas of mathematics match up with the reality of how the physical world works.
In May, he is coming out with a new book, “Brilliant Blunders: From Darwin to Einstein – Colossal Mistakes by Great Scientists That Changed Our Understanding of Life and the Universe.”
His most important lesson?
“It’s important to be curious,” he said.
That – rather than astrophysics – was the topic of a talk he gave recently, which will soon be posted at Ted.org.
“They say curiosity is contagious,” Livio said in the talk. “Let’s make it into an epidemic.”