A scientist claimed that he felt his dream last 100 years? If a human being rarely lives beyond 100 years, how could he know, what 100 years of time feels like?
Most probably it’s just the “filling of the gaps” function of the brain. If you had a dream which started at 2012, and then the scene changes to year 2112, you automatically assume that the dream was very long. It’s, of course, logical to assume that, but it doesn’t mean you were dreaming during that long period of time.
Dreams can seem to last long if a lot of things happen while dreaming. A dream where you simply go outside of your house doesn’t seem to last as long as a dream where you go outside, run around, get back home, get some breakfast and then fly up through the chimney. Even if the duration of these dreams were the same, you would guess, that the second one lasted longer, since your brain involuntarely assumes, that if more things happened, it had to take up more time. As I mentioned somewhere in another topic, we humans are awful at guessing the amount of time that passed, since we measure time by the quantity of actions in a dream. Anyways, if you succeed in having a 100 year long dream, good for you. Just, so you know, it’s not scientifically possible, according to S. LaBerge proof I posted a few posts above.