In the absence of an empirical observation, how does the scientific community agree on what happened?
Loeb: If there is no empirical data, then the community will never agree because there are always multiple options. People are not just convinced by theoretical arguments; they really need to see the evidence. It’s sort of like a detective story; unless you have the clues, the story will not be accepted in court. We have observed directly the cosmic microwave background—radiation that is a relic of the Big Bang, so we know that the Universe was denser and hotter in the past. But we haven’t yet figured out inflation, the fast expansion of the universe very early in its history from a space smaller than an atom to a cosmos 100,000,000,000,000,000,000,000 [100 sextillion] miles in diameter. Some people are still skeptical about inflation, but there is a whole community of people doing calculations that would help test the theory. A & S: What kind of observations could test that theory? Loeb: One experiment is to detect gravitational radiation, ripples in space time that were generated by
