J.C.MacSwell

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?

Well, obviously over some distances of 200 million light years it is happening (45-50 km/s) or it would not happen at all, period.(correct?) You mean within Galaxies? Edit:"obviously" may not be my best choice of word with regard to that rate at that distance...

them = Stars in a Galaxy as per the OP Obviously any expansion effect is undetectable over the distance to the moon. Is this also true for 100,000 light years? (I don't know) Can gravity exactly compensate for expansion at any scale?

Could the Hubble expansion displace them outward over time? Assuming the expansion is proportional to distance, and gravity is proportional to the inverse square law (though it seems otherwise, if only detectable mass is assumed)... Is there any observable outward movement (how many years might that take?)

When I first came across relativity, I took a few days off school to try and wrap my head around it, and figure out what was really happening, so I could carry on with my Newtonian life... Failing that, I went back to school... Later I found Quantum physics very puzzling, and therefore very interesting. 2nd law of thermodynamics I found more intuitive, but equally fascinating, and when quite young I was amazed how gyroscopes seemed to cheat gravity.

That would be a lot safer. It would keep your arm from heading off into orbit by choosing too light a paper ball. Edit: Seriously, neither arm nor bow is anything close to an idealized "momentum transferring device", as suggested in your OP, that could apply a force of 50N for .05 seconds regardless of how light the arrow or ball.

A lot of these objects can't be identified...and there seems to be more sightings...by more people...with more technology. It is almost uncanny!

You are given the momentum. You want the smallest mass possible to achieve the highest velocity and gain the maximum energy. The higher velocity the higher the drag force in air, generally proportional to the square of the velocity. So your optimum will depend on the coefficient of drag and frontal area, and coefficient of skin friction and surface area, of the arrow.