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When Galaxies Collide
neutron_p writes "An international team of scientists announced today, they observed a nearby head-on collision of two galaxy clusters. The clusters smashed together thousands of galaxies and trillions of stars. It is the most powerful events ever witnessed. Such collisions are second only to the Big Bang in total energy output. The event was captured with the European Space Agency's XMM-Newton observatory. Scientists are calling the event the perfect cosmic storm: galaxy clusters that collided like two high-pressure weather fronts and created hurricane-like conditions, tossing galaxies far from their paths and churning shock waves of 100-million-degree gas through intergalactic space."
It's not as if we wouldn't see it coming. Of course, if we're still stuck on this rock...
And don't forget the wipe-out-nearly-all-life gamma ray bursts! No advance warning on those puppies.
"You might as well get your son a ticket to hell as give him a five string banjo." -unknown minister
Since the celestial an planetary bodies are extremely far apart relative to their size, wouldn't the galaxies just pass through each other without colliding at all?
It the universe is expanding due to the Big Bang, then why would galaxy clusters ever meet?
You are being MICROattacked, from various angles, in a SOFT manner.
Or at least look at the 'artist's impression'.
They may be small and far apart, but the rules of physics does not allow preclusion from stuff like gravity and whatnot.
I felt a great disturbance in the force. As if millions of voices suddenly cried out in terror, then was suddenly silenced.
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It the universe is expanding due to the Big Bang, then why would galaxy clusters ever meet?
The short answer is: because the Universe on these scales is not perfectly homogeneous. If it were, they wouldn't merge.
The longer answer:
Remember that the expansion of the Universe is an expansion of background space -- an expansion of the space in which everything is embedded -- rather than stuff moving through space. The rate of change of the relative separation of two hunks of matter can then be thought of as having two components: one from the expansion of space (objects staying in the same location, but the distances between objects are increasing because space is expanding), and one from the movement of objects through space (objects changing their locations in space). In the case of the latter -- the so-called "peculiar velocity" of an object -- if matter were distributed perfectly smoothly throughout the Universe, there'd be no reason for anything to change locations in space. But it isn't; and so there are net gravitational forces on objects that cause them to move. Whether the attraction of two objects "wins" over the expansion tending to separate them depends upon the situation.
For a simple way to picture this sort of thing, consider a big rubber sheet with two marbles on it. Give one a nudge towards the other (its peculiar velocity), and then start stretching the sheet (the expansion of the Universe). Will they collide? Depends on the peculiar velocity, rate of stretching (expansion), etc. But it's certainly not the case that they always won't.
I just can't get my sky is falling hysteria worked up over a galactic storm that takes 100 million years to occur. I hope these folks aren't planning on watching the whole thing from beginning to end.
You can tell a great deal about the character of a man by observing those who hate him.
How would it affect the Earth? Well, as long as no stars come too close to us, we'd probably not really be affected at all. We might get thrown out of our galaxy or something, but as long as nothing smacks right into our planet or our sun, and nothing distorts our orbit signifigantly, I wouldn't expect any real problems other than the nighttime sky changing ...
"All of a sudden, causality decided to give physical laws and time the finger,
Actually physical laws appear to have given causality the finger quite a while ago.
Last I heard we were due to collide with the Andromeda galaxy. It must be around the hundred million or billion year range, though.
The living have better things to do than to continue hating the dead.
Obviusly, is not the first time it happens. Not so obvius, is not the first time this has been studied, either.
By the way, there's a slighty more detailed article in space.com., some other useful links in the article, also.
Excerpt from space.com:
Contains further information, videos, pictures.
x ym erger_media.html
http://www.gsfc.nasa.gov/topstory/2004/0831gala
And don't forget the wipe-out-nearly-all-life gamma ray bursts! No advance warning on those puppies.
Although that's only because we don't know anything about them.
If one started happening near enough for it to bother us, I suspect we'd notice *something* going on beforehand. Energy can't just appear suddenly and randomly, it has to come from some source. And gamma ray bursts are a LOT of energy. I'm way too lazy to actually look it up, but I think it's at least on the scale of like, if an antimatter star collided with a matter star and they instantly turned each other into 100% pure energy at e=mc^2 (m is enormous, c^2 is enormous, guess how big their product will be), it still wouldn't be enough.
I mean, I'm with you on the whole "they're astoundingly big and powerful" thing, but I suspect for that very reason one wouldn't just pop up nearby without us noticing something weird well beforehand.
Random and weird software I've written.
Crap! Two galaxy clusters collide and I missed it!
Anyone know what time it happened?
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Did anyone notice the "Mergers & Acquisitions" ads by google? Considering the funding woos of NASA, perhaps......
Stay sentient. Don't drink bad milk.
This seems like an good excuse for the network beeing down yesterday :)
A little stupidity is as unlikely as a little pregnancy
Also, gravity will generally only make two stars collide under very specific conditions -- what will usually happen instead when two stars wander into the same area is that their paths will be deflected by the other, or maybe they'll go into orbit about each other. But without a way to shed the angular momentum, they're unlikely to ever collide unless their initial paths are *just* right.
But if it ever happens (two stars actually colliding, especially big ones) ... I'll bet it's one hell of a show! (as long as you're far enough away to be safe from the resulting nova/super nova/black hole -- not that a black hole would be any more dangerous than the two stars that combine to create it, of course.)
Well, a giant star has a large gravity field, and if two giant stars were to collide, it would be even larger, but that's really about it.
If a large star got close enough to us to affect the local gravity field enough to affect time, we'd all be dead long before, so there's little reason to worry about that. It takes seriously strong gravity (by terrestial standards) to signifigantly affect time, and anything that came even remotely close to doin that would destroy the Earth first (not to mention distrubring our orbit, which alone could cause massive global catastrophes.)