These are some challenging physics and math based questions, sort of like trivia though a few haven't been answered. You should all give them a shot. http://star.tau.ac.il/QUIZ/ [Broken] Ill put in white what I think of some of the unanswered ones. 01/04 - Isotropic Universe I do not think the S would ever be detectable if it had a random distribution of scatterers that had random orientation. From a probability standpoint, there is a finite probability of deflecting toward O, P(DT); a probability of deflecting away P(DA). The problem is, assuming a random distribution, you have an equal chance of deflecting away as you do toward (P(DT) = P(DA)). So the net difference would be 0. The only thing I can think that would make this difficult is the fact that though its random orientation, there is not an infinite number of scatterers, thus over time you may see a trend. So If you were told "in this region of space there may or may not be Scatteres" and you compared the distribution over time to that of the rest of your input, you could see a difference. But if you were trying to locate if there was one anywhere there would be no way to tell where it actually was. Though you may be able to tell that there is an uneven distribution of where particles are coming from. This is also assuming you dont know its size. 08/03 - Why is a pillow soft? Seems like I'm missing something here. If by "soft" they mean something that has an exponential damping curve that, then it is due to 1. Restriction of displacement of air thru the material. 2. The feathers create enough of a "spring" to displace the material when there is no load on it, thus its equillibrium is a larger volume than when its flat. 3. Feathers, due to their geometry, are very durable when being compressed. They can stay soft for many uses. Though over time they can break and trear, thus resulting in a pillow that is no longer soft. 11/02 - Inviscid Motion My question is a thermodynamics one. Can turbulence (changes in pressure) cause changes in Temperature in inciscid liquids? If so, then there will be loss of Total Energy of the motion of the sphere due to this turbulent generation of heat. I am assuming the sphere is in a box that has this liquid filled to its max volume, and there is no way for volume to change or to lose liquid. Though I do assume you can have temperature, such as a heatsink attached to the box. What do you guys think of some of the unanswered ones?