Andromeda Collision VS Expansion

In summary, the two conflicting claims about Andromeda's fate are based on different time scales. Andromeda is currently coming towards us, but will eventually collide with the Milky Way. Meanwhile, it's unknown when or if interstellar travel will ever become possible.
  • #1
newrd
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Hi Folks,
I've read that by the time mankind is ready for intergalactic travel, our nearest galactic neighbour will be too far to even travel to. But I've also read that Andromeda is on a collision course with the Milky Way. Which is correct? And if the universe is expanding and everything is moving apart, how come we're not moving away from Andromeda?
Thanks!
 
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  • #2
newrd said:
I've read that by the time mankind is ready for intergalactic travel, our nearest galactic neighbour will be too far to even travel to.
Where did you read that? Quoting sources helps us help you - if you've got something wrong, we can see if it's because you've misunderstood something, or if the author of what you read misrepresented something.

I tend to suspect whatever you were reading was a bit fanciful. "When we'll be ready for intergalactic travel" simply isn't something we can know. But anyway, nearby galaxies aren't moving that fast on the kind of time scale we're likely to be around.
newrd said:
But I've also read that Andromeda is on a collision course with the Milky Way.
Andromeda is certainly coming towards us.
newrd said:
And if the universe is expanding and everything is moving apart, how come we're not moving away from Andromeda?
On small scales (less than a hundred million light years), plenty of stuff is moving in all directions relative to us. It's only beyond that kind of distance that you see the overall picture of "everything moving away from us". This is, basically, because the "speed" with which things recede from us grows with distance. At low distances, random velocities of the galaxies can be larger than the average expansion motion.
 
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  • #3
newrd said:
Hi Folks,
I've read that by the time mankind is ready for intergalactic travel, our nearest galactic neighbour will be too far to even travel to. But I've also read that Andromeda is on a collision course with the Milky Way. Which is correct? And if the universe is expanding and everything is moving apart, how come we're not moving away from Andromeda?
Thanks!
Honestly, there's just no possible way to make any statement about when intergalactic travel may or may not happen.

Interstellar travel looks to be so unimaginably difficult that it might well be impossible. We have no idea when interstellar travel might happen (if ever), let alone intergalactic travel. You just can't put a timeline on something when you have no idea how it can ever occur.
 
  • #4
Thanks guys, Ibix your answer that its on a small scale explained it perfectly, cheers!
 

1. What is the Andromeda Collision?

The Andromeda Collision refers to the predicted future collision between the Milky Way galaxy and the Andromeda galaxy. It is estimated to occur in about 4.5 billion years.

2. How does the Andromeda Collision compare to the Expansion of the Universe?

The Andromeda Collision is a localized event, involving the collision of two galaxies, while the Expansion of the Universe is the overall movement of all galaxies away from each other. The two phenomena are not directly related.

3. Will the Andromeda Collision have any impact on Earth?

No, the Andromeda Collision will not have any impact on Earth or the Solar System. The distance between galaxies is so vast that the collision will not affect the movements of planets or other celestial bodies.

4. How do scientists know that the Andromeda Collision will happen?

Scientists use observations of the movement and positions of galaxies, as well as computer simulations, to predict the future collision of the Milky Way and Andromeda galaxies. These methods have been used to successfully predict other galactic collisions in the past.

5. What will happen to the Milky Way and Andromeda galaxies after the collision?

After the collision, the two galaxies will merge together to form a new, larger galaxy. The exact appearance and structure of this new galaxy will depend on the specific dynamics of the collision.

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