# Time taken for gravity of a distant object to interact with a newly created particle? [duplicate]

Possible Duplicate:
The speed of gravity
Does gravity travel at the speed of light?

Imagine there is a large mass $m_1$ (e.g. a star) 1 light-year away from us. It is stable, stationary relative to us and has been in place for a long time, much more than a year. A small mass $m_2$ (e.g. a proton) has just been created locally, 1 light-year away from $m_1$.

How much time does it take for $m_2$ to feel the gravitational pull of $m_1$, and how can this be explained with the virtual-graviton theory of gravity?

Some possible answers I can imagine:

a) Immediately $m_2$ interacts with virtual-gravitons sent by $m_1$, a year ago.

b) 1 year. It takes this long for freshly launched virtual-gravitons from $m_1$ to reach $m_2$ and vice-versa before any effect is felt on either mass

c) 2 years. There needs to be an exchange of information / virtual-gravitons between $m_1$ and $m_2$ and this is the minimum time it could take.

d) None of the above

## marked as duplicate by user10851, Waffle's Crazy Peanut, Qmechanic♦Jan 20 '13 at 6:39

• – user10851 Jan 19 '13 at 19:33
• @Chris White I do not think either if these questions are duplicates, one is about FTL information exchange (which I am not covering), one is about speed of gravity transmission (which is clearly speed-of-light). I am asking a different question about the nature of gravity. – roblev Jan 19 '13 at 19:46
• Okay, Roblev. Removed the tag. Atleast, you've mentioned it. BTW, Keep in mind that we use TeX markups for equations, parameters, etc. :-) – Waffle's Crazy Peanut Jan 19 '13 at 19:53
• @CrazyBuddy thanks, will try to master the markup next time – roblev Jan 19 '13 at 20:03
• Possible duplicate: physics.stackexchange.com/q/5456/2451 – Qmechanic Jan 20 '13 at 6:38