The pattern of density fluctuations that result after inflation—arising, I should stress, from the quantum fluctuations in otherwise empty space—turns out to be precisely in agreement with the observed pattern of cold spots and hot spots on large scales in the cosmic microwave background radiation. While consistency is not proof, of course, there is an increasing view among cosmologists that, once again, if it walks like a duck and looks like a duck and quacks like a duck, it is probably a duck.
