But that form of artificial gravity doesn't do dick to help alter other forces such as acceleration or deceleration of the whole ship. It has limited value (space stations or mid-transit coasting).

 

well you could put on magnetic shoes?!

 

He didn't ask about grav or anti-grav propulsion. Just "Artificial gravity", which was explained in the second post.

 

I recently saw a show on Discovery or some such channel about a possible manned mission to Mars and some of the dangers, one of them being muscle and bone density loss due to an extended period of zero-gravity. As raj said, NASA uses rotation to create artifical gravity but is currently working on a vessel that will simulate gravity without making the astronauts sick. Pretty interesting stuff.

 

The force of gravity is proportional to mass; mass is what creates gravity.

The reason that a small piece of lead creates more gravity than a large amount of cotton is that the small piece of lead has more mass. Ten grams of lead and ten grams of cotton produce the same amount of gravity.

Only if you insist on comparing objects by their volumes - a distinctly bizarre means of comparison in context. Objects of equal mass produce equal gravity; density be cursed.

Because they're more massive.

They produce more gravity because they have more mass. They're smaller in volume because they're more dense.

Mass and distance are the only parts of the equation. The force of gravity between two objects of masses m1 and m2 respectively separated by a distance of r is F = (G * m1 * m2) / r^2, where G is a constant (that depends only on the units of measurement for mass, distance, and force). Note that density doesn't appear.

 

magician beat me to the punch but the equation for the force of gravity is

F=Gmm/r^2

Density has nothing to do with that equation.

 

The fun bit with a black hole vs a red supergiant is that you can get much, much closer to 100% of the mass of a black hole. Think of a red supergiant that's 651 million miles across - if you could get to 100 miles from the center of that object, you'll have mass evenly distributed around you, for a net gravitation force of essentially zero. Now, concentrate that mass into a black hole - when you're 100 miles from that object, ALL the mass will be on one side of you and exerting an absolutely huge force on you.

Getting back to the original question - the current theory of gravity, from what I understand, doesn't allow for any anti-gravity, artificial gravity, or gravity/mass nullification like you see in some science fiction.

 

Yup.

 

Of course, there's always the theory of intelligent falling...

 

Quite the interesting topic, and good discussion so far. Magician seems to have it pretty much locked down. I do think the centripetal force idea seems as close as we can get. After all, gravity is just an acceleration force, same as a centripetal.

It's also quite interesting that of the 4 known natural forces (gravitation, electromagnetism, strong and weak nuclear) gravity is the one that we are the most familiar with, and yet we know the least about. I guess since we cannot really manipulate it to produce usable energy, nobody seems too concerned about it.