I recently heard it suggested that the weakness of gravity, compared to the other fundamental forces, might be explained if it “leaked” into other universes  that are adjacent to ours in a higher dimension.  If this were so, might the gravity from those universes not also leak into ours?

As I understand it, we infer the presence of “Dark Matter” from its gravitational influence, and suppose it to comprise the majority of matter in our universe, despite our inability to observe it directly. Might its invisibility be because it is not in our universe?

This explanation seems also to offer possible causes for other discrepancies between our expectations and our observations of gravitational effects such as that associated with Pioneer.

My cat will land on her feet when dropped from any reasonable height from any position -- even when on her back from a height slightly higher than her own height.  

Clearly she has a connection with gravitiy.  If she were in the ISS how would this effect her reactions?

Please do not suggest a real experiment.  Give her the dignity of Schrodinger's cat.

 Glaciers flow across landscapes carrying boulders and debris e.t.c. Until recently I always assumed they travelled downhill, but I hear they can carry boulders uphill. How is this gravity defying feat possible?

Ian Jones, Solihull, UK

If three bodies each move at constant angular speed, each following a trajectory given by r=R.(1+K.cos(A+n.120)) and each of these bodies rotates about its own axis in a manner that balances out the torque variation due to radial change, what angular velocity must the system rotate at before a gravitational force starts to be resolved at the system reference point in the direction A=0?

Even as a physics major I have to scratch my head looking at the varied descriptions of why there is a tidal bulge of water on the side opposite the moon.  Some argue it's centrifugal force, some argue it's gravitational gradient. So here's a serious question -- if the Earth and the Moon were simply held apart by a big stick, and not rotating, would there still be a bulge of water on the side away from the moon?

I have been taught that acceleration due to gravity is affected by surface area and not mass. I still find it hard to believe that a situation like in my question would be possible?

Say there was a tunnel that went through the centre of the Earth that came out on the exact opposite side to the entrance. If you jumped down it, would you have the momentum to fly out of the other side, or would you be pulled towards the Earth's centre of mass and be crushed? This is assuming of course that the person will not burn :P

If I hold a ball in my hand, I've noticed that if I open my hand, rather than the ball staying where it is, it travels with increasing speed towards the ground. This phenomena seems to be widespread - in fact it seems to happen with all matter on Earth. My question is, why does the ball behave like this?

I was having a argument at collage about what would happen if the world would suddenly spin the other way. would you be flung the way the world was spinning or would you not realy notice any affect on your self. I am looking for the answer to end the arguing.

Over the billions of years that the Earth has been orbitted by the Moon, its rotation has slowed by the slight resistance to the tide as it travels round the planet (relative to the Earth of course, it would appear static relative to the Moon).  The tide is of course caused by the gravitational pull of the moon and the equal and opposite gravitational forces of the Earth and the Moon keep the Moon nicely in orbit around the Earth.

As the force causing the braking effect of the tide is exerted by the Moon's gravity, there should be an equal and opposite force to the braking that is being exerted on the Moon.  As the tide is working as a brake on the rotation of the Earth, it would be expected that the bulge of tidal water is slightly ahead of the Moon with the Moon's gravity pulling it back.  I suspect that this bulge slightly offsetting the Earth's centre of gravity out of line with the Moon's centre of gravity and the Moon's centre of rotation might have some such effect.

Admittedly the effect would be rather small, but over the periods of time such as the time it has taken for the Earth's rotation to change from 6 hours per day to 24 hours per day surely there has been some effect.  If so, am I right in thinking that the Moon's orbit has quickened over time?  If so, I hope the Moon has stayed in equillibrium by adjusting its altitude (is that the right word?) and isn't thinking of leaving us to it once it has built up an escape velocity...