gravity

[steveb]

what is the speed of gravity? if an object the size of the sun were suddenly to appear how long would it take for an object say 10 light years away to feel the gravitational pull from it? is it the speed of light? or slower? im sorry the question isnt worded very well couldnt really think of a better way of asking it.

cheers Steve

[TommyDobry]

I don't believe that it would be possible for a massive object to just suddenly appear but if you believe Einstein, no signal or effect can travel faster than light. I believe that if an object did suddenly appear 10 light years from Earth today,the gravitational effects would be felt 10 years from now. It is believed that gravity is a wave phenomenon, like electromagnetism and travels at the same speed 186,283 mi./sec. in a vacuum. 

[steveb]

cheers, it was a hypothetical question, i am aware it would be quite hard for an object that big to just appear, lol

[Clanad]

There are, currently, two theories attempting to explain how gravity works, the older Newtonian and the newer Einsteinian.  It's generally accepted that  Newton's classic explanation and equations are now a subset to Einstein's theory.  But what they do agree on is that, at the atomic level, every particle in the universe has a gravitational affect on every other particle.   Current theory, however allows that it's actually the energy density that determines the strength of the attraction.  The attempt to completely define gravity as well as correlate it with all other force fields has produced the study of a more general Unified Field Theory (UFT) that shows how all of the known force fields work together. Once understood, this new UFT explains several heretofore unexplained phenomena in nature.  This study has given birth to a new set of terms, including diallel, gravitational-field lines.  The moving charges and particles in the diallel lines set up the condition for the gravitational information to flow between the two bodies providing the gravitational interaction. The velocity of the gravitational information is a function of the conditions � typically at or faster than the velocity of light.  The conditions needed for the gravitational field are two objects with some energy density (not just mass) and with diallel lines running between these two energy-density objects, which diallel lines are conducting particles, i.e. electrons, protons, neutrons, etc. These diallel lines then provide a conduit for the gravitational band of frequencies to communicate and generate a gravitational interaction between the two objects. It's important to understand that all aspects of this theory are still being studied.  (Contd.)

[Clanad]

Contd.

The point being, in reference to your question, is that there already existed gravitational attraction between the atoms that finally made up your hypothetical large body that suddenly appeared.  It would have only increased in strength by it's increase in size... (With explanatory assistance from Allan's Time)

[fo3nix]

it is the speed of light. 3x10^8 m/s.

[mibn2cweus]

An objects gravitational pull would coincide with its appearance.  With an object 10 light years away both would 'appear' as they were ten years ago.

[DocRob]

Here's a wrinkle in the answer: 'inventing' that mass would require a certain amount of energy, as E=mc^2...

The wrinkle is that the energy, alone, would curve spacetime the same way as the mass, even if it were a gas of gamma photons (no rest-mass) that spontaneously all created electron/positron pairs ('pair production'). So that energy, itself, in whatever form, would have the same gravitational effects. All you could do is shuffle the distribution of energy in space, to arrange a small tight mass, but you'd already have the gravity that went with it.

Energy and mass really are equivalent for this.

[mibn2cweus]

Please simplify & clarify if posible:  If object (x) is revolving around object (y) would object (x) appear visually in the same direction as its gravitational pull?

Is my previous answer valid?