Greene is not only a respected researcher, but is also an engaging and entertaining ambassador of the field.
Greene explained that Galileo Galilei and Isaac Newton pioneered the use of math to gain insights into the nature of reality — even when the equipment to test the theory may not yet exist. This powerful technique succeeds to this day.
Sometimes the math leads in directions that seem impossible or absurd, yet that is when the discoveries can be greatest.
Einstein was able to develop his theories of relativity by asking the kinds of questions a 5-year-old might ask. “How does gravity really work?” for example. Then he let the math and the physics take him wherever they might go — however impossible the answers might seem.
The result was a world in which space itself warped to create what we call gravity. It was only later that a solar eclipse allowed the theory to be confirmed, by watching the sun’s gravity warp the light path from a distant star.
Belgian priest and physicist Georges Lemaître radically applied Albert Einstein’s theory to the entire universe. He concluded the universe cannot be static. It must be expanding or contracting based on the raw math of general relativity. Einstein said Lemaître’s math was brilliant, but the physics was abominable. Einstein should have realized not to dismiss the physics just because the result was surprising.
Lemaître was, in fact, correct. The universe was expanding, as Edwin Hubble discovered. And we now know of the force behind the expansion as “dark energy.” Einstein’s own equations allowed gravity to repel as well as to attract.
This repulsive energy is so great that there is more than enough to drive our own big bang and cosmic expansion. There is enough left over to create bubbles of other universe creation.
Greene’s original research is in string theory, the theory of the very small. But there are now vast numbers of different string theories. The idea of multiple universes gives a chance for each of these different theories to exist, each in its own universe.
Thus, the study of the very small connects with the study of the largest of all — the “multiverse” of all possible universes.
Not all physicists are so quick to resort to such radical solutions. But Greene said we should try to observe the existence of these other universes. What a great achievement that would be for our generation, to establish that ours is not the only universe, Greene concluded.