[thedoc (OP)]

Jon asked the Naked Scientists:
   
If there was a equal mass of Hydrogen or uranium would they both generate the same gravity? Or any gravity?

What do you think?

[jeffreyH]

Yes

[Bill S]

Yes

Surely, gravity depends not just on the mass, but also on the degree to which it is compacted.  Wouldn’t that mean that the uranium would be likely to cause greater spacetime curvature? 

[jeffreyH]

Yes

Surely, gravity depends not just on the mass, but also on the degree to which it is compacted.  Wouldn’t that mean that the uranium would be likely to cause greater spacetime curvature?

The OP did not ask about the strength of the gravity just if it would be the same. It would generate the same type of gravity as any other mass. As to the density issue that is something I have looked into over and again. Field strength is indirectly caused by mass density but it is the actual field density that matters. This density can be caused by several masses that are distributed in an area of space and does not necessarily have to have one single mass as a source. There is an interesting relationship between spherical geometry and field strength that can be used to determine particle densities over distance. This applies to any field with force carrying particles. The individual particle energies remain constant. This means that ultimately matter does not radiate away gravitational energy. Energy is conserved and exchanged between masses.

[CliffordK]

I suppose one could argue the difference between mass and weight, but mass is essentially a measurement of gravity.  So, YES, equal masses would have equal gravity.

The one caveat is the effect of surface distance.  So, for example, if the moon was made of solid Lead, or solid Hydrogen, but of the same mass, then standing on the surface of the lead ball, one would be much closer to the center of mass than one would be when standing on the surface of the solid hydrogen ball.  Thus, one would experience greater gravity on the surface of the lead ball.  However, if one was equidistant from the center, the gravity would be the same.

[syhprum]

Is there not still a small doubt about this I believe that experiments have been conducted to try and confirm this but they are very difficult to set up and are not conclusive.
It is not as yet fully confirmed that matter and anti-matter produce the same gravity although the expectation is that they do.