Imagine sitting in front of a computer screen and electron microscope, waiting for the moment that would make or break your theory. You're sampling glacial deposits from three time periods: the Younger Dryas Boundary, and the layers immediately above and below. You think a comet broke into fragments (think Shoemaker-Levy) and hit the Earth, leaving no discernible impact crater but doing a serious disservice to the gigantic mammals running about. You're at the make-or-break moment: if nanodiamonds, which would help confirm your theory, are found sprinkled liberally in the layers above and below the Younger Dryas Boundary, your theory is good as dead. Have you made a true discovery? Were you on the wrong track?
The moment of truth comes. You see those glorious black speck scattered throughout the Younger Dryas Boundary - and only the Younger Dryas Boundary.
I'll let geologist James Kennett describe that moment when a breakthrough is made:
Moments of intense discovery are very emotional for scientists. when scientists make discoveries that they think are really important - breakthroughs, if you like, eureka moments - there's an elation - there's an elation, an emotion. These are emotional moments.-from Nova, "Last Extinction"
So much for scientists being emotionless drones, and science itself being boring ol' number-crunching, eh?
The story of their search for evidence for their impact theory was interesting enough, but I loved that Nova episode more for what it showed about science. It's hard work, sometimes dull work, and there are no guarantees. But when it all comes together, it's glorious. And it can move you to tears.
Pretty amazing. There's interviews with the discoverers and other info at this link, if you're interested.