2 ms·
Looking at just the Earth-Sun interaction, Earth is moving in a gravitational field that is unchanging. It's not that Earth is being pulled towards where the s
by andrewla 8y ago
Looking at just the Earth-Sun interaction, Earth is moving in a gravitational field that is unchanging. It's not that Earth is being pulled towards where the sun was eight minutes ago, but rather that it continues to move in free-fall in a region of space-time that is curved in a time-invariant manner.
If the sun were to vanish completely, then an observer above the elliptic of the solar system would see Earth transition from an apparently curved orbit to a straight-line path approximately 8 minutes after the sun's vanishing.
- BurnGpuBurn 8y agoThank you for your answer. I've heard the "it's an unchanging gravitational field" argument before, but it doesn't really explain the question for me. If the suns gravity is a field, then why is the movement of that field (which is locked to the suns mass I presume) instantaneously "known" to the earth, so the earth "free falls" in the curved space time in the right direction holding its orbit. Why doesn't the earth, at 1 au, free fall into the space time curvature that was created by the sun 8 minutes ago? It certainly appears the earth "knows" where the sun is now, which would imply instant information travel. I also think you contradict yourself in your last statement, in which you say that the gravitational field of the sun does take 8 minutes to reach earth.