I am genuinely curious about this. I *kind of* understand that gravity, like light, moves at the speed of light (right?). So then would our solar system, and millions of other star systems, just continue orbiting what USED to be the super massive black hole in the center of our galaxy, if said black hole just suddenly (hypothetically) collapsed/vanished? How does that not violate the laws of physics?
Furthermore – let’s say a star… a hundred light years away went supernova. We’re still receiving it’s light for a hundred years right? It would just look totally normal to us in the sky, for the next hundred years. Well let’s say that supernova was so awesomely powerful as to truly push our planet out of orbit from our sun. What happens first? Does that star’s supernova explosion light up in the sky, or does that impact from this supernova hit us and cause catastrophic damage? What’s faster – the impact or the supernova?
I really want to understand distance/time better as it relates to astrophysics, I just can’t comprehend the insane distance and the deltas between distance + time = what we experience on earth. It’s truly humbling.
In: Physics
The speed of light is the speed limit of the universe. Nothing can propagate throughout space faster than the speed of light.
So, changes in gravity propagate throughout the universe at the speed of light.
As for a supernova, you have to realize that there is no matter in space for a shock-wave to propagate through like here on Earth. In order for us to feel an impact from a supernova, we would have to be hit with ejected material and light *from* that supernova. Since the ejected material does *not* move faster than light, we will see the light first before being hit by anything else.
It’s also important to note that the speed of light is not the limit *because* light moves that fast, but rather the reverse. Light in a vacuum just cannot move faster than that speed limit. It is a universal constant.
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