[allmost]

Instantaneous propagation would revert back to Newtonian concepts. It's my understanding that variations of the speed of gravity vary from, but are close to, the speed of light. Binary pulsar decay rates have been observed which tend to corroborate that assumption. If it is (IMO most likely) a function space-time itself then the rate could be inconsistent in different times and places in the Universe. That is unless the inherent random fluctuations (energy) of Casimir’s elastic metric concept are uniform. I personally think it varies.

[who_would_fardels_bear]

If the force of gravity travels at the speed of light wouldn't we be able to observe that in our own solar system?

The earth is about 45 minutes away from Jupiter. Wouldn't we be being tugged by Jupiter from where Jupiter was 45 minutes ago, rather than where Jupiter is now?

Is this effect so small that it is still unmeasureable or has someone already looked into it?

Just wondering.