How can Andromeda collide with the Milky Way?

Jur van Oerle
Messages
9
Reaction score
1
If everything in the universe is moving away from everything else in the universe, how can Andromeda collide in the distant future with the Milky Way?
 
Astronomy news on Phys.org
Jur van Oerle said:
If everything in the universe is moving away from everything else in the universe...
Because this part isn't true. Locally, galaxies interact with each other.
 
So, what exactly do people mean when they say 'everything is moving away from everything else'?
 
Jur van Oerle said:
So, what exactly do people mean when they say 'everything is moving away from everything else'?
You have to keep in mind the scales. Galaxies at distances of billions of light years away are all moving away from each other at significant speeds due to the expansion of space. However the Andromeda Galaxy is only 2.5 million light years away. The magnitude of its speed away from us that is due to the expansion of space is far smaller than the magnitude of its speed toward us due to its existing momentum and gravitational attraction between the Milky Way and Andromeda.

If someone is telling you that everything includes local galaxies in this case, then they don't know what they're talking about.
 
  • Like
Likes   Reactions: CalcNerd, davenn and berkeman
Alright, that makes sense.
I think it is my own ignorance, when I watch YouTube channels like Vsauce and MinutePhysics that is what I understand from it.
Thanks for clarifying!
 
  • Like
Likes   Reactions: Borg

Similar threads

  • · Replies 17 ·
Replies
17
Views
4K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 30 ·
2
Replies
30
Views
6K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 5 ·
Replies
5
Views
4K
  • · Replies 87 ·
3
Replies
87
Views
11K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 3 ·
Replies
3
Views
4K