J.C.MacSwell

So...we all agree that Nature is a lazy, but efficient, hard working but wasteful bastard?

Thanks. Can no longer edit but will know for next time.

Sorry, don't know how to add spoiler (could someone help?) 1.Balance 4 and 4, if they balance the remaining 4 have the odd ball, and you have 8 that are known to be standard 2a. Measure 3 of the remaining 4 against 3 standard, if they balance the final ball is the odd ball. 3a. Balance the odd ball against a standard ball to determine if it is heavy or light 2b. If measure #2a did not balance you know that the 3 are heavy or light... 3b. Balance 2 of the 3 to find the odd ball (heavy or light) or if they balance the third of the 3 is the odd ball If measure #1 does not balance you have 4 balls known standard, 4 which may contain an odd heavy ball, and 4 which may contain an odd light ball 2c. Measure the four standard balls against 3 possibly heavy and 1 possibly light, if they balance you have 1 possibly heavy and 3 possibly light 3c. Measure the 1 possibly heavy and 1 possibly light against 1 possibly light and one standard, if they balance the remaining possibly light is the odd ball (if not you can pick out the odd ball and know whether it is heavy or light) If measure #2c does not balance and the unknown side is light, you have your 1 light odd ball in that group and do not require a third weighing If measure #2c does not balance and the unknown side is heavy, you have 3 possibly heavy balls 3d. measure 1 possibly heavy against 1 possibly heavy, if they balance the third possibly heavy is the heavy odd ball If they do not balance the heavy side is the heavy odd ball.

Well, then it depends on how close to equilibrium you will accept...or possibly until the one just like ours contracts, if it ever will, or never, since we do not know how ours will end either. The equilibrium limit will not be reached otherwise, classically speaking.

Depends on how close to equilibrium you will accept. Or... A background radiation will be created given long enough if the Universe is small enough (closed system). If this Universe is contracting at some point exact equilibrium could happen.

The model is incomplete...so there is, obviously, 100% probability that it is not 100% correct.

Just for the record...what is the current record? Just over 100Kmph? Something about a motorized winch, even if prior to the timed attempt, rubs me the wrong way. What about using a "soft" kite assist to launch, which can be jettisoned after take-off, perhaps from a lightweight catamaran? Not that it really makes a difference to the main challenge...

That is by far the best perpetual motion machine design I have ever seen!

The basics of this are certainly no more difficult than the basics of the science he is studying. The key is to find the right book at the right level in the right area of interest. Too bad his teachers can't help out with that. (any suggestions?) Josh, make sure you cover your course material first but go ahead and challenge yourself otherwise. If you have the interest the start of the "long road" might be fun, and if so I bet you will learn it very quickly.

Rumenentary, my dear Watson.

I would not call that a boundary layer. I would still interpret that as a boundary. In the usual sense boundary layers have a defined thickness, even if that thickness is somewhat arbitrary, shifting, or fuzzy, and the character of that thickness is essentially different from what lies outside of it.

They would know when because xmas day came and went, and by examining there own they would realize, not from checking a few but checking the whole million, that the others must have been opened from the bottom or top (or if the others forgot to open them on xmas day they should be able to recognize that as well) Again this scheme could violate causality or relativity so something cannot be right, it should be impossible to send information faster than light speed...

Does it come out of black holes?

Now imagine doing that a million times, and finding out that opening the box from the top revealed a blue ball 60% of the time, and opening it from the bottom revealed a blue ball just 40% of the time...and you kept repeating this and finding the same results...so you conclude that their colours are not predetermined before opening. So you then take a million matched sets of boxes a light year apart, and open half of them, all in one way, on xmas day. When the others a light year away are opened on boxing day, it would seem information could be gleaned from the results, knowing that the xmas balls were planned to be opened from the bottom only if it snowed that day...but this should not be possible, since a network of ball stations could relay the information back in such a way that the information was received the day before xmas, to help with the weather forecast.

What assumptions should we use to evaluate this question?

At 56 microns it looks to me like everything where α >1 is in the excluded or shaded area, and everything where α<1 is not excluded. So what is the correct interpretation of this if not what I stated?

If I am reading the graph correctly the Eöt-Wash Group experiments around 56 microns indicate there is no excess gravity at that distance. They have not ruled out a drop in gravity from what would be predicted by the inverse square law. I assume the discs would have to be even closer than 56 microns apart to make the test in any case, to produce any torque attributed to gravity within that range.

I think in principle you are on the right track. You are trying to maximize speed through the water using the energy available from the difference in velocities between the water and the air. Efficiency, lift to drag, is key, the right balance of areas of the foils/wings and as already noted control, which is the toughest thing to get right in practice. The interesting thing is the optimum depth for the foil and angle to the surface which will effect the drag of the cable (or cables). Normally depth is controlled with buoyancy or a system that reduces lift in the foils as the foil system rises toward the surface. Similarly the wing or wings must be angled optimally and in the right direction for best thrust, minimizing drag, and maintaining the right altitude. The rest is just "squeezing the pea" as hard as possible in ideal conditions...high wind, little turbulence and flat water.

Well, he did explain a lot to his disciple Galnewtstein, but his writings were largely ignored at the time and he is largely forgotten.

The first half of this video describes the Oet-Wash Group effort http://www.learner.org/courses/physics/unit/unit_vid.html?unit=3 Rather than tiny masses they are using discs with coincidental rings of holes that, when rotationally misaligned, create a gravitational torque.

It was. I meant prior to originally posting the thread. Thanks again.

Thanks. I had tried different wording and found nothing prior to posting, but will try that.

Thanks DH. That seems more in line with what I was after, although it is closer than I expected. I'm not sure how much could have been inferred from variances of orbits, unless I am missing something that would still be distant affects. At sub millimeter the masses have to be quite small just to "fit" in the experiment so I wonder what assumptions are in place to get that result. So, the gravitational attraction of 2 (very small) masses at 1mm could be measured to quadruple (approximately) at 0.5mm?

Hi IA I'm not looking for anything to rigorous, just a more or less accepted (proven) distance where if you move 2 objects closer you get roughly the expected change. The nature of the decreasing distance would, I think, make measurement difficult as other forces dominate and the masses would have to be correspondingly smaller...but I wondered how close they have reasonably come to approaching zero distance and to what accuracy with inverse square still apparent.

Does anyone know the experimentally measured minimum distance where the inverse square law holds?