（8月6日20点更新,21点已发放金币）庆祝会员数破千，活动——抢楼，有奖!

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An experimental physicist performs an experiment involving two cats, and an inclined tin roof.
The two cats are very nearly identical; same sex, age, weight, breed, eye and hair color.
The physicist places both cats on the roof at the same height and lets them both go at the same time. One of the cats fall off the roof first so obviously there is some difference between the two cats.
What is the difference?
One cat has a greater mew

a mathematician?
If an engineer walks into a room and sees a fire in the middle and a bucket of water in the corner, he takes the bucket of water and pours it on the fire and puts it out.
If a physicist walks into a room and sees a fire in the middle and a bucket of water in the corner, he takes the bucket of water and pours it eloquently around the fire and lets the fire put itself out.
If a mathematician walks into a room and sees a fire in the middle and a bucket of water in the corner, he convinces himself there is a solution and leaves.

A Princeton plasma physicist is at the beach when he discovers an ancient looking oil lantern sticking out of the sand. He rubs the sand off with a towel and a genie pops out. The genie offers to grant him one wish. The physicist retrieves a map of the world from his car an circles the Middle East and tells the genie, 'I wish you to bring peace in this region'.
After 10 long minutes of deliberation, the genie replies, 'Gee, there are lots of problems there with Lebanon, Iraq, Israel, and all those other places. This is awfully embarrassing. I've never had to do this before, but I'm just going to have to ask you for another wish. This one is just too much for me'.
Taken aback, the physicist thinks a bit and asks, 'I wish that the Princeton tokamak would achieve scientific fusion energy break-even.'
After another deliberation the genie asks, 'Could I see that map again?'

The experimentalist comes running excitedly into the theorist's office, waving a graph taken off his latest experiment. 'Hmmm,' says the theorist, 'That's exactly where you'd expect to see that peak. Here's the reason (long logical explanation follows).' In the middle of it, the experimentalist says 'Wait a minute', studies the chart for a second, and says, 'Oops, this is upside down.' He fixes it. 'Hmmm,' says the theorist, 'you'd expect to see a dip in exactly that position. Here's the reason...'

One day in class, Richard Feynman was talking about angular momentum. He described rotation matrices and mentioned that they did not commute. He said that Sir William Hamilton discovered noncommutivity one night when he was taking a walk in his garden with Lady Hamilton. As they sat down on a bench, there was a moment of passion. It was then that he discovered that AB did not equal BA.

The answer to the problem was 'log(1+x)'. A student copied the answer from the good student next to him, but didn't want to make it obvious that he was cheating, so he changed the answer slightly, to 'timber(1+x)'

Researchers in Fairbanks Alaska announced last week that they have discovered a superconductor which will operate at room temperature.

A student recognizes Einstein in a train and asks: Excuse me, professor, but does New York stop by this train?

At the physics exam: 'Describe the universe in 200 words and give three examples.'