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As time passes, we will be able to see objects that are further away, as their light eventually reaches us. Since gravity also travels at the speed of light, would we be able to detect when a super heavy object came within the visible universe?

Colin
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  • Are you asking "in theory" or "in practice"? – James K May 25 '23 at 22:47
  • It depends on how superheavy it is and what "detect" means. If it's an experimental apparatus that measures gravity, I don't think we routinely measure anything besides the Sun and Moon, and those can be measured with relatively simple equipment (probably at a few locations on Earth) and careful analysis, or just watching the tides go in and out. OR do you mean "detect" by it's gravitational effects on other distant astronomical objects we can observe? – uhoh May 26 '23 at 07:27
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    Does this answer your question? Is it "nonsense to even talk about" objects outside the observable universe not having gravitational influence on us? (finite speed of gravity) The first answer addresses about as clearly as possible why this won't happen. – antlersoft May 26 '23 at 14:09
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    @uhoh The latter. For example, the moon would be influenced between ±1.3 seconds before or after the earth, depending on the relative direction to the object. I'm guessing the effect would be too small to be noticeable. – Colin May 27 '23 at 00:20
  • @JamesK Would the effect be measurable in practice. – Colin May 28 '23 at 07:28
  • @antlersoft The answer you refer to explains why events outside the observable universe can't be detected - that's not my question. I'm asking whether the gravity of objects entering the observable universe would be detectable, when their electromagnetic radiation would be visible. – Colin May 28 '23 at 07:33
  • If there is no evidence for gravity effects from beyond the horizon this suggests that dark matter isn't beyond the horizon and so can't move faster than light and is therefore obeying relativity theory. –  May 28 '23 at 13:54

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