After commenting on a few threads that are dedicated to astrophysics. I decided to make a short little tidbit on black holes; Why? because they're unbelievable, and most people don't really understand the concept. I assume the reader has a basic understanding of the gravity and black holes in this thread. In addition, I assume a hypothetical impossible situation, I understand why it cant happen but am trying to make a point.
As far as the community of scientists are aware, a black hole is not an actual hole in space and time where if you were sucked into it, you could essentially pop out into another universe (multiverse) or separate part of our universe. (possible, but not the general idea as it stands)
As most of you are aware, when large stars are at the end of their life cycle. The star would then explode as a supernova then potentially compress down into a finite point; thus creating a black hole. But! This is a question most of you will think you know the answer to.
"What would happen to the solar system and trajectory of our planets if our Sun suddenly *poof* collapsed in on itself and became a small black hole?"
Well besides the fact that we would all freeze and die, nothing would happen...
Nothing would happen to the planets, their moons, the asteroid belt, or anything in our solar system. Nothing would be sucked into the mass, and no trajectories would change.
As we are all familiar with the theory of gravity, we'll start there. Gravity is calculated by the Mass of the two objects involved, and their distance from each other. So the gravitational pull the Sun has on the earth is dictated by each of the objects masses and their distance from one another.
Now when that sun suddenly *poof* turns into a black hole, its mass is still the same, the earths mass is still the same, and the distance is still the same... thus the core reason why the earth would continue on its original path and so would everything else. Mass and distance of the objects don't change!
This idea may go against what most of you assumed. Most people assume Black holes are millions of miles across, and when a star collapses in on its self, entire solar systems get obliterated as they get sucked into the black hole. This simply is not true.
I'll try to explain this as best I can...
The closer you get to an object, the less distance separates the two masses, and the gravitational force is increased. Lets say we scale the sun down to occupy a 1 meter radius to the core. As we move closer and closer to the sun eventually we would hit the surface... we cannot get any closer! At this point our gravitational pull would be maximized... 1 meter from the core of the star.
Now we take this Sun and compress all that mass into one tiny point of a needle.
- Its mass is still the same (just occupy's less space)
- Our mass is still the same
But! now we aren't maximizing the gravitational pull 1 meter from the suns core, were able to get closer and closer and closer; the gravitational force would get larger and larger and larger. Until eventually we would be sucked in. Somewhere between the black hole's surface (point of a needle) and the outer layer of where the sun was (1 meter radius) would be a point called the event horizon where not even light could escape. To put it into perspective; A black hole that has 3x the mass of the sun, has an event horizon of only a few miles across.
In conclusion, just because a star collapses in on its self, doesn't mean its gravitational force increases drastically from what it had when it was a star and begins sucking everything into it that was millions of miles away...
EDIT: The Sun is much too small to take the "black hole route" upon its death, instead it will turn into a white dwarf star. Also, the earth will be obliterated by the preceding Red GIant and not be here when the black hole exists.
However, this article assumes the impossible hypothetical situation where the sun just suddenly poof's into a black hole, skipping the expansion of a Red Giant. The reason is because I'm trying to explain the effect of how the gravitational force the black hole has on objects does not ever change on the masses around it.
Kind of a fun topic in an area not a ton of people are too familiar with. Hope I explained myself clearly.
Edited by Neufy161, 19 September 2012 - 08:29 PM.