# If Mass Curves Spacetime, How does It Uncurve Again?

Part 3

The Sun’s Disappearance

Gravity isn’t instantaneous, but only travels at a limited speed:
The Speed of light.

And that gravitation isn’t determined by mass and position directly, but by the curvature of space, which itself is determined by the full suite of matter and energy throughout the Universe.

Action-at-a-distance was here to stay, but Newton’s “Infinite range force through static space” was replaced by spacetime curvature.

If the Sun were to simply wink out of existence, disappearing from the Universe, we wouldn’t get to know it for some time.

Earth wouldn’t immediately fly-off in a straight line; it will continue orbiting the Sun’s location for another 8 minutes and 20 seconds.

It isn’t mass that determines Gravitation, but rather the curvature of space, which is determined by the sum of all the matter and energy in it.

If you were to take the Sun away, space would go from being curved to being flat, but that transformation won’t be instantaneous.

Because spacetime is a fabric, that transformation would have to occur in some sort of snapping motion.

You know how Thanos ‘snapped’ everyone out of existence!

That snap would send very large ripples of gravitational waves through the Universe, propagating outward like ripples in a pond.

Like, the way they show you in End Game. Large amounts of energy hurling through the Universe; a large energy outburst thing.

P.S. Always pay attention.

Part 1 Newton’s Law of Gravitation

Part 2 Newton Was Wrong About Spacetime Being Absolute

Categories: science

### 8 replies ›

1. This explanation of the curvature of space is both helpful and fascinating. If the sun winked out, there would only be minutes to find out and then to consider our own annihilation. I doubt the probe presence around the sun would have time to tell us much before its own extinction. Maybe probes of the inner planets or on the moon or in our own (near-Earth) sky could tell us something. If we look the other way (literally), what could be happening away into the cosmos that might us affect us like the dying of our Sun? I guess it’s not only a matter of the timing of detection but also of events actually happening in a progressive way. So if the universe ended out there a billion years ago, it would take a while to find out about it–and then more time before it happened to us, yes?

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2. Interesting posts – all the three. I need some clarification! You have said:
“If you were to take the Sun away, space would go from being curved to being flat, but that transformation won’t be instantaneous.
Because spacetime is a fabric, that transformation would have to occur in some sort of snapping motion.”

In one place you have said it won’t be instantaneous and then you have said it would be snappy. Isn’t that instantaneous 🤔

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• I didn’t say it would happen in a snap.
I said it would send ripples after the snap and then it would take time for those ripples to set in.

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