Challenge Definition and 911 Threads

Ok, is there any solid, liquid, or gas that becomes heavier as it gets warmer and lighter as it gets colder? Like a reverse lava lamp. The little physics I know says no but I Know VERY little, you know? CJ

Newton's laws? there is an athlete climbing a rope in gym class. he gets to a point halfway up the rope and is stationary. someone puts a bag of sand that is equal in weight to the athlete. they are both static and then the athlete starts to climb the rope, slowing and speeding up at random...

Ram has a rectangular piece of card board out of which he clipped away the largest possible square and was left with a piece similar in shape to the original piece. The area of the piece remaining with Ram forms approx what percent of the original piece

A new claim has appeared in physics. It is claimed that there is a largest possible force, namely c^4/4G or 3 x 10^43 Newton. (The claim is made in the paper http://xxx.lanl.gov/abs/physics/0309118 ) All my friends and acquantances have first said "wrong!" but then failed to produce a...

Would you accept to be chosen to perform the experiment of the quantum suicide?

http://www.bbc.co.uk/science/humanbody/body/interactives/senseschallenge/

I challenge you to name at least one area of physics that the work of Einstein did not somehow affect. If you take this challenge, you, like your pathetic parents, are destined for failure. eNtRopY

I wonder if you could scale this experiment up with a human it could be fun, mind you I am not convinced that the pioneering little frog was alive for very long, if you watch the movie it also seems that only one side of its body works but maybe its just confused or enjoying itself :/ see...

Who will be the first to prove that (with one exception) the sum of any Prime Pair is always divisible by twelve?

Given - 1) Twin earth-sized planets rotate about each other in a solar system. 2) The plane of their mutual orbit is the same plane in which they rotate about their star 3) Their star provides (on average) the same amount of energy as our sun Questions - 1) What is the size and nature of...

(a) When there is a phase-to-neutral fault on a transmission line, will the existence of the neutral wire increase or decrease the magnetic field under the transmission line? Why? (b) Assuming that the whole space consists of an upper half space with soil resistivity r1 and a lower half...