Colliding galaxies mark Hubble anniversary Aficionados of galactic pile-ups can avail themselves today of a set of 59 Hubble images of colliding galaxies, released to commemorate the 18th anniversary of the space telescope's launch. The dramatic snaps, constituting the "largest collection of Hubble images ever released to the public", include this close encounter …
OK, it's boring Thursday.....and if I could borrow someone elses' braincells for 0.005 seconds, I might be able to answer this myself....but.....
If we believe in the Big Bang theory and that there was a single point of origin that "exploded" x billion years ago......forming the Universe.........so why now (or rather some few million years ago, given that the light from the picture in question took an awfully long time to get to us).......are these two huge galaxies colliding?
If all the particles from the Big Bang were all sent out in different directions heading AWAY from a central point, how come these at least one of these two galaxies (or any others for that matter) is moving in a different direction and is approaching this other galaxy ???
Surely the universe is expanding.....and whatever time it took to form these dust clouds, that doesn't allow them the time to stop going AWAY from the origin of the Big Bang and to then change direction and to now be about to hit this other one?
I can't figure this out...and I doubt there are any other forces (dark matter?) strong enough to make a galaxy turn around without pulling it apart ?
After the big bang, the matter created wasn't sent hurtling in different directions through space. Instead, the space began to expand and continues to expand to this day. Matter, however, travels through space in all sorts of directions, buffeted hither and thither by various forces and two particles might well collide. That's how stars and planets formed. Ultimately, it's how we all formed.
You may be interested to know that the andromeda galaxy is hurtling through space on a path that will lead it to collide with our own galaxy many billions of years hence. Something to look forward to.
The two galaxies colliding are due to 'random motion'. Similar to the vortexes you get if you drop an object into liquid, it's the same idea. So one sort of swings round, and collides with the other one.
It's going to happen with the Milky Way and the Andromeda Galexy in something like 100million years or so.
hth :)
Why do galaxies collide? Simple: gravity. Yes, the universe is expanding so that on a large scale everything is getting further away from everything else. However, the matter in the universe is not evenly spaced and some clumps of it are closer together than other clumps. If two clumps (in this case galaxies) are close enough then their mutual gravitational attraction will pull them together and they will end up merging. This process can be seen in our own galaxy as it is currently in the process of gobbling up at least one satellite dwarf galaxy that got too close, and in approximately 3 billion years time an event much like the Hubble pictures will happen when the Milky Way and Andromeda galaxy collide.
This happens on an even larger scale than 'just' galaxies. Our galaxy is one of a group of about 30 that and on top of all the interactions between these galaxies, the group as a whole is being drawn towards something else. What that something is is a mystery at the moment and it is know simply as The Great Attractor.
Attn: AC
The universe did not start at any one "single point" that is identifiable. The ENTIRE universe was that one point, so we can say this was the point of origin of the universe or anything else. The expansion of space does not imply that no matter will ever meet any other matter (good thing, that, or we wouldn't exist); it just implies that ON AVERAGE and particularly on large scales things are flying apart at an impressive clip. If what you said was accurate then there would exist NO blueshifted objects at all in the cosmos which is not the case. There are simply more redshifted objects than blueshifted objects.
A good example of an approaching body is the Andromeda Galaxy, which is moving towards the Milky Way at an impressive clip and in a few hundred aeons or something it'll collide with our own galaxy.
Good question, AC. A layman's attempt at an explanation (any visiting astrophysicists - please correct me):
Matter on a scale of millions of light-years is very 'lumpy'. Most galaxies exist in clusters, which may contain thousands of galaxies gravitationally bound to each other. "Gravitationally bound" implies that the attraction between them is sufficiently strong (or they're falling together sufficiently quickly) to more than compensate for the expansion of the space between them.
Within these clusters, collisions are possible and relatively frequent - given that a collision takes place over many millions of years we can see quite a lot of them in differing stages. Our own local cluster includes the satellite galaxies of the Milky Way (principally the Magellanic Clouds) and the Andromeda galaxy. We will collide with the latter in a few billion years time (booking early is essential if you would like a good seat :).
The reason that galaxies could collide is because the gravitational mass and therefore forces of the two galaxies exceeds the force of the universe expanding and hence bringing them together, whilst also moving with the expanind universe. That's my understanding of it anyway, I might be wrong. The Big Bang theory relies heavily on gravity being the key to everything however there are alternative theories that could be conisered better.
There are a few flaws in the Big Bang's theory concerning the age and shape of the universe. It uses dark matter to attempt to plug its holes, and this is yet another theory based on a theory. Some of the alernatives opt for an infinite universe, no start or end, other theroies consider that perhaps the universe is governed by electricity, gravity and magnetism. At the end of the day, it's one big head f*** and we as humans haven't even scratched the surface.
Dancing round each other like rain kissed lovers
gravity singing whale whilst capturing others
the Multiverse is eternal and full of stars,
held within another's celestial grasp.
The big bang theory and dark matter story
of expanding gases, sub atomic blast in history
our 'verse is ever steeped in mystery
and the deep abiding sense of long ago history...
I'm such a good IT engineer tho' :-)
The expansion of the universe is tough to grasp. The best explanation I have had is by analogy. Try to imagine a two dimensional man who lives in a two dimensional world on the surface of a balloon which is slowly being inflated.
As far as he's concerned, his entire (2 dimensional universe) is expanding. As he's only two dimensional, he has no concept of up or down, so there's no central point from which his universe expands; it just keeps getting bigger, seemingly from nowhere.
All the time this expansion is going on, he lives his life normally. In fact, his two dimensional glaxy attracts nearby two dimensional galaxies exactly as if the universe were not expanding (OK, it's a BIG balloon). They are still attracted to each other, even thought the balloon is getting bigger.
We're just the same, except that we're clearly three-or four dimensional aware, and the expansion is occurring at right angles to OUR reality.
Paris, because she's the one who explained this to me.
O
> The universe did not start at any one "single point" that is identifiable. The ENTIRE universe was that one point,
unless it was a string
> The expansion of space
measured with a ruler (or piece of string) that is "outside" space presumably. Likewise the bloke on the expanding balloon will also get bigger as well, unless he is a being from another "dimension"
> Most galaxies exist in clusters, which may contain thousands of galaxies gravitationally bound
assumption which fails for spiral galaxies and globular clusters (without ad hoc assistance from metaphysics)
> Has anyone told Lembit "Cheeky Boy" Opik about this?
more to the point has anyone told amanfromMars
The analogy of the balloon is a bit off. If it was like this, then all objects would become larger and stretch out along with the expansion. 2D has up and down, it doesn't have true depth.
A better analogy is to imagine compressing a sponge to an infinitely small size, then releasing it. Everything expanding out at the same time, yet each molocule maintaining its original size. There is no real center, as everything already existed; and no matter what perspective you view the expansion from (within the sponge itself), appears to be the center.
Even though the Hubble telescope was originally flawed (the main mirror was incorrect), the fixes and improvements made by the Shuttle since have led to it becoming the best instrument for this kind of astronomical picture. The results alone justify the expense of maintaining a fleet of Shuttles. How can we (I suppose as NASA) even conceive of letting it fall into disuse?
My cynical side wonders if this is a part of Shrubs attempt to replace science in American culture and policy with (mis-guided) religion. Let us hope the next president, whoever that turns out to be, can and will reverse this Luddite policy!
Meanwhile, thank you for steering me to these FANTASTIC pictures.
As to "A Very Bad Day", remember that galaxies are mostly empty space. Colliding galaxies tend to merge or rearrange themselves, but the great majority of the stars within them will survive these collisions, even though they may be moved from their original orbits within their original galaxy, and even end up in the other if the result is not a merger. One can expect most planetary systems (such as ours) to survive such a collision with only minor effects. The collisions take many millions of years in any case (galaxies are typically many 100,000 light years across, and their relative motion is a small fraction of the speed of light).
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