High School Andromeda Collision VS Expansion

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SUMMARY

The discussion clarifies that Andromeda is indeed on a collision course with the Milky Way, despite the universe's overall expansion. While the universe is expanding, galaxies within a hundred million light-years can exhibit random motions that can counteract this expansion, leading to Andromeda approaching the Milky Way. The feasibility of intergalactic travel remains speculative and uncertain, with no timeline established for when such travel might be possible.

PREREQUISITES
  • Understanding of cosmic scales and distances in astronomy
  • Familiarity with the concept of galaxy motion and gravitational interactions
  • Knowledge of the universe's expansion and Hubble's Law
  • Basic grasp of interstellar versus intergalactic travel concepts
NEXT STEPS
  • Research the dynamics of galaxy collisions, specifically the Milky Way-Andromeda merger
  • Explore Hubble's Law and its implications for cosmic expansion
  • Study the concept of cosmic inflation and its effects on galaxy movement
  • Investigate the technological challenges of interstellar and intergalactic travel
USEFUL FOR

Astronomers, astrophysics students, science enthusiasts, and anyone interested in the dynamics of galaxies and the future of space travel.

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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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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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.
 
Thanks guys, Ibix your answer that its on a small scale explained it perfectly, cheers!
 

Thread 'Estimates — True Size of the Universe?'

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