Interesting that galaxies can collide without a star hitting another star.. but would it also be that the distances are so vast that the stars dont even (or mostly dont even) affect each other?
I don't know about the percentage of affected stars in a typical galaxy collision but note that you don't need a collision for two stars to affect each other. We're not speaking of interaction like on a pool table. The gravity will significantly affect star systems that pass significantly close from each other.
> I don't know about the percentage of affected stars in a typical galaxy collision but note that you don't need a collision for two stars to affect each other.
True, but the way in which they affect each other is that they try their best to collide.
From that perspective, it's kind of weird if collisions don't happen.
Is it? Think of a single star during a galactic collision. It wants to collide with every star in the other galaxy. It gets pulled this way and that, so, in sum, it decides to collide with the oncoming galaxy as a whole. Unfortunately, despite having billions or trillions of stars, that other galaxy is mostly empty space. The poor original star that we were tracking was unable to collide with any star at all.
Well, why do we keep attempting to collide with the Sun instead of striking out for the center of the Milky Way? Everything you just wrote applies just as much to the Earth as it does to a star heading through a foreign galaxy.
Why would stars hit each other during galactic collisions when stars inside of a single galaxy already almost never hit each other? Apparently reading it here of all the stars in the galaxy, a stellar collision only happens once every 10 000 years.
Interestingly enough, when galaxies collide, the supermassive black holes at their centres do typically merge as their gravity is strong enough to attract each other.
It's by the way not particularly unlikely for stars to pass through other solar systems. Apparently about 70 000 years ago a binary star system flew through the Oort Cloud.
Thinking of the scales involved, even at the speed of light probably two masses couldn’t pull each other fast enough to collide (if you are colliding the two galaxies at the fastest manifestible speed which is the speed of the light).
That’s hand wavy because if you’re imagining like grabbing the two galaxies and smashing them together… that’s like giga levels of magnitude faster dynamics than the speed of light, ha!
You’d have to like put the galaxies on top of each other and leave them there, probably for years, for gravity to get everything moving quickly enough (and then for the speed of light to even bridge the distance!) before really anything would happen. I think.
An other aspect is that orbital mechanics are weird/chaotic. Specially when you get masses that are similar scale. Like why hasn't moon hit earth yet?
So with two galaxies colliding I would not expect the stars to hit each other as result of collision. But as result of interactions when speeds increase.
