Andromeda Galaxy colliding with the Milky Wa

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    Andromeda Galaxy
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Discussion Overview

The discussion revolves around the potential collision of the Andromeda Galaxy with the Milky Way in approximately 3-5 billion years. Participants explore the scientific basis for this event, including measurements of Andromeda's velocity and the implications of galactic mergers, while also expressing skepticism and curiosity about the broader consequences of such an event.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants question the certainty of the Andromeda collision, seeking proof beyond theoretical models and computer simulations.
  • It is noted that Andromeda's velocity towards the Milky Way is measurable, but the transverse velocity is more uncertain, leading to indirect estimates.
  • One participant mentions that galactic mergers are common, citing images of other galaxies colliding as evidence.
  • Concerns are raised about the nature of the collision, with some arguing that it may not be dangerous for stars and planets due to the low probability of direct star collisions.
  • Speculation arises about the existence of extraterrestrial life in Andromeda and the implications of a collision for potential interactions with such life.
  • Participants discuss the challenges of interstellar travel and the likelihood of encountering aliens, suggesting that the collision may not significantly alter these probabilities.
  • There is acknowledgment that the Milky Way is currently absorbing another galaxy, which raises questions about the visibility of such processes to the general public.

Areas of Agreement / Disagreement

Participants express a mix of skepticism and acceptance regarding the collision event, with no clear consensus on the certainty of the predictions or the implications of the collision. Multiple competing views remain regarding the nature and consequences of the event.

Contextual Notes

Participants highlight the indirect nature of some measurements related to Andromeda's velocity, as well as the complexities involved in understanding galactic dynamics and the potential for life in other galaxies.

Who May Find This Useful

Readers interested in astrophysics, galactic dynamics, and the potential for extraterrestrial life may find this discussion relevant.

zytyxx
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Hi... Just wondering... Will the Andromeda galaxy really collide with the Milky Way in 3-5 billion years? I've seen a supercomputer-generated video, but is there any actual proof other than the theories of various scientists? Even though it was NASA who came up with it...
 
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zytyxx said:
Hi... Just wondering... Will the Andromeda galaxy really collide with the Milky Way in 3-5 billion years? I've seen a supercomputer-generated video, but is there any actual proof other than the theories of various scientists? Even though it was NASA who came up with it...
Probably, yes. The main uncertainty here is how fast Andromeda is moving to the side. It's really easy to measure how fast it is moving towards us: that's done by just estimating the shift in the light coming from Andromeda's stars and gas clouds (it's moving towards us at 117km/s). But it's very difficult to estimate how fast Andromeda is moving to the side, and the estimates for that are extremely indirect.
 
The transverse velocity of Andromeda is estimated at no more than 120 km/s, so a merger event appears probable [re: http://arxiv.org/abs/astro-ph/0506609] ].
 
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Chronos said:
The transverse velocity of Andromeda is estimated at no more than 120 km/s, so a merger event appears probable [re: http://arxiv.org/abs/astro-ph/0506609] ].
Yes, but as I mentioned that's a very indirect measurement. I really wouldn't trust those errors, personally.
 
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zytyxx said:
Hi... Just wondering... Will the Andromeda galaxy really collide with the Milky Way in 3-5 billion years? I've seen a supercomputer-generated video, but is there any actual proof other than the theories of various scientists? Even though it was NASA who came up with it...

There are lots of pictures of other galaxies in the process of colliding, so we know galactic mergers are pretty common. You seem skeptical - do you have any reason to doubt that such a collision will happen?
 
Keep in mind gravity will be pulling the center of mass of both galaxies toward each other with increasing strength over the next few billion years.
 
Chronos said:
Keep in mind gravity will be pulling the center of mass of both galaxies toward each other with increasing strength over the next few billion years.

True, but that really just means they are in going into an orbital path about each other. By analogy, as a meteor approaches Earth, it too is pulled with increasing strength - but that's just all part of its trajectory - it also speeds up as it nears. Either its elliptical/hyperbolic intersects the Earth or it does not. This does not change as it nears Earth.

That being said, galaxies are not solid bodies, which means, closer than a certain distance and their paths can't be treated as a point on a path any more. Whether they actually merge or not, they will almost certainly be dramatically distorted - probably sprayed across the sky.
 
phyzguy said:
There are lots of pictures of other galaxies in the process of colliding, so we know galactic mergers are pretty common. You seem skeptical - do you have any reason to doubt that such a collision will happen?

Not really. It just seems so hard to believe. :rolleyes: Oh well. It's probably going to happen. Too bad I'll be long dead when that happens. I wonder if our solar system will get thrown into intergalactic space? :confused:
 
I just had a scary idea. If there are aliens or just other organisms living on the Andromeda Galaxy in one of the systems, isn't it possible that we could be living with aliens in the future? I just hope the aliens are amenable (if they exist at all). :eek: I sure hope not, but the chances are really pretty much 50/50 (in my opinion, anyway).
 
  • #10
Bear in mind that this 'collision' will probably not be a dangerous event for any living things orbiting stars in the two galaxies. The chance of two stars colliding is very small. Our Milky Way galaxy is currently in the process of absorbing at least one other galaxy(see below), and we didn't even notice (unless we're professional astronomers).

http://en.wikipedia.org/wiki/Sagittarius_Dwarf_Elliptical_Galaxy
 
  • #11
zytyxx said:
I just had a scary idea. If there are aliens or just other organisms living on the Andromeda Galaxy in one of the systems, isn't it possible that we could be living with aliens in the future? I just hope the aliens are amenable (if they exist at all). :eek: I sure hope not, but the chances are really pretty much 50/50 (in my opinion, anyway).
Well, it's not really any more likely that there are aliens in Andromeda than there are aliens here in the Milky Way, so the collision won't noticeably increase the probability of aliens visiting. The fact that aliens haven't visited us yet, though, suggests that it's pretty unlikely, that the difficulties of interstellar travel really are tremendous enough that interstellar travel is almost never undertaken (if ever).
 
  • #12
phyzguy said:
Bear in mind that this 'collision' will probably not be a dangerous event for any living things orbiting stars in the two galaxies. The chance of two stars colliding is very small. Our Milky Way galaxy is currently in the process of absorbing at least one other galaxy(see below), and we didn't even notice (unless we're professional astronomers).

http://en.wikipedia.org/wiki/Sagittarius_Dwarf_Elliptical_Galaxy

No, I did not know that. It's pretty amazing that the Milky Way is in the process of absorbing another galaxy. I haven't even ever heard of the Saggitaurus Galaxy. :confused:Everyone else I know is owrrying about other things... No time for astronomy... :zzz:Oh well. I know about it now!:approve:
 
  • #13
Chalnoth said:
Well, it's not really any more likely that there are aliens in Andromeda than there are aliens here in the Milky Way, so the collision won't noticeably increase the probability of aliens visiting. The fact that aliens haven't visited us yet, though, suggests that it's pretty unlikely, that the difficulties of interstellar travel really are tremendous enough that interstellar travel is almost never undertaken (if ever).

Yup. That is a REALLY good point. It will definitely increase the chances by very little, but it still won't be even likely. Interstellar travel is very interesting. If only spaceships could move at the speed of light...
 
  • #14
The universe has conspired to quarantine all intelligent life forms to their local star systems. The energy required for interstellar [much less intergalactic] travel is virtually incomprehensible, not to mention too expensive to be politically feasible.
 
  • #15
Chronos said:
The universe has conspired to quarantine all intelligent life forms to their local star systems. The energy required for interstellar [much less intergalactic] travel is virtually incomprehensible, not to mention too expensive to be politically feasible.
I do rather hope we get around to it at some point, though. Difficult as it may be.
 

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