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Comment by raverbashing | Hacker News Reader

Very low probability times massive number of stars: yes I think there will be a non-zero number of actual collisions

You are confusing one big number with another big number, and treating them as the same.

Yes there are a lot of stars. It's a big number. But there's a lot of space. That's a number that's in a whole different league.

For example, the whole solar system is about 2 light-day diameter. But it's 4 light years from the nearest star in any direction. Empty space is thus many orders of magnitude more than solar systems, never mind suns.

Sure there's a probability of a collision. But even multiplied by the number if stars, it's still really tiny.

I would agree, except for some factors:

Gravity tends to bring heavy objects together

Andromeda and the Milky Way are not colliding "like two pancakes on top of each other" but at an angle to each other

Also star surroundings are usually places where you can collide with a lot of stuff (asteroid belts, dust, etc)

We're not shooting a goal on a 4 light-year wide goalpost (btw that's the density on our vicinity, but on other areas the density is higher) but passing multiple stars on an environment that can be perturbed and heavy things attract each other

This entire conversation seems silly without a time frame. Over a long enough time with continually interacting orbits, of course mass will coalesce. I don't think "merge" means "one time interaction that fully disperses the mass", anyway.

If they merge in 7 billion years, you think over the eg next 7 billion there won't be kinetic collisions? I'm skeptical.

If they merge in 7 billion years, I wouldn't count a collision in year 13 billion as a result of colliding galaxies. It would be just a normal behavior of stars colliding in the new galaxy that was formed.

Well, you certainly should—that's how causation works.

There is no Universal Saftey Insitute where they test crash Galaxis , and we have no idea if the indivual stars in a galactic collision will line up such as there mutual gravitational atractions leads to head on collisions. Both galaxis are rotating and presumably there are sections ,unknown and unknowable, that will interact much like gears meching, where the chances of collision are much higher over time. Reducing the whole thing to a simple probability of something like two fields of dots, pushed strait through each other may not be valid, and I am absolutly cetain that no one has the compute needed to run a simulation on billions of varied gravitational singularities moving and interacting with another set......... which is of course all my lead up to do a pitch for a mega intraferametric space telescope to observe actual coliding galaxies and other phenominon, to be built sooner, rather that later. would also be good for looking at details on exo planets.....give it a realy wide focul length and it could also zoom in on asteroids and comets for research, early warning of impacts and determining potential space mining candidates. current work in space navigation is focused on providing ultra high precision data links between different satelite units in an array that will alow introfermetry to work without a physical conection between the sensors, making for larger, cheaper telescopes, that are orders of magnitude more powerfull than anything built yet

We should all close our eyes and imagine the insanity of two stars directly colliding. My goodness.

I mean spin down collisions are a common enough occurrence and likely happen at higher speeds.

Also watching stars getting disrupted by black holes would be similar.

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