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Milky Way & Andromeda Collision
Frédéric writes: "A lof of people know that our Sun will be a red giant in about 15 billion years, and its size will increase dramaticaly beyond the Mercury orbit and we will burn. But do you know that the Andromeda Galaxy will collide with our Milky Way in about 3 billion years, a first time, then another time after 1 billion years to merge themselves, what a mess! There is some pretty nice simulations in MPEG, and a lot of pictures with some explanation. The simulator use 24 million particles, they are planning a 120 million particles simulation."
How is this a Troll?
AFAIK the total lifetime of our sun is about 8 billion years, with 4 billion years old that makes it up to 4 more billion years left for us.
The whole universe is about 12-18 billion years old. Our sun is a second generation star, build mostly of matter left from other, first generation stars. (this is the reason why there is matter with higher atom mass than iron on earth, it's the remains of supernovas.)
John Dubinski uses a parallel tree code. basically a Barnes-Hut tree with the 'local essential tree' method for parallelising. The ~O(N) FMM is a nice idea and works well in 2D, but in 3D it's a major memory hog and O(NlogN) trees are better.
:-)
http://xxx.lanl.gov/abs/astro-ph/9603097
his new code (which I'm working on too) is better
You can simulate colliding galaxies on your home computer using the Galcrash java applet. There are also several other nice astronomy java applets on this website. It's a cool way to spend the afternoon.
Yay astronomy!
In the big picture, on average, the universe is expanding. Compared to the overall scale of the universe, however, our local group of galaxies is a very small thing, so local motion within the group is the effect we see.
You assume uniform density of stars. So the chance of star collision on the periphery is much smaller than the probability you gave, but the chance is much higher if center collides with periphery, or even higher if center collides with center. What's the chance of star collision if center collides with center?
First off you're right on about radio waves. My guess is that there's some way to communicate (if not actually travel) FTL.
And yeah, I also doubt the idea of massive colonization. It seems likely that most civilizations able to progress to the point of having that technology would first have to stabilize their population. Without exponentially expanding population, there's no need to colonize millions of worlds(and anyway, who wants to go live on planets where the air is toxic to you - which I bet for any given life form most planets would be).
Long ago, I wrote up a more accurate n-body simulator called XStar, along with an introductory text on the n-body problem. XStar isn't that accurate either, as it is only a 2D simulation, rather than a 3D simulation, and the dynamics of a million particle system is very different than a system with only a couple dozen stars. Still, it is pretty accurate for what it does and will give you some insight on how stuff really works.
To give you some idea how old XStar is, it was designed on a 33MHz 486 on a 1024x768 display. If you run it, make sure you add more stars, as in "xstar -b 50" or even "xstar -b 200" if you have a fast computer.
--
SPF support for most open source mail servers can be found at libspf2.
The stars don't collide as such, true, but the orbits of the stars around the galaxies obviously change significantly. More importantly, the gravitational shockwaves (visibile as spiral arms etc.) cause regions of the interstellar medium to collapse and begin star formation.
You could also imagine that as the orbits of stars are altered, so will the object orbiting them, so you might find that, eg the planets of a solar system like ours would be showered by comets and meteors.
It would be interesting to see if new "stable" multiple star systems would be formed. Would solar systems combine? If two stars came close, would they eject each others planets?
Sounds like a very interesting field of research.
:)
I'm out of my tree just now but please feel free to leave a banana.
"There's one thing every scientist on the planet agrees on: whether it happens in a hundred years, or a thousand years, or a million years, eventually our sun will grow cold, and go out. When that happens, it won't just take us, it'll take Marilyn Monroe, and Lao-tsu, Einstein, Maruputo, Buddy Holly, Aristophanes - all of this. All of this was for nothing, unless we go to the stars."- J. Michael Strazynski
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
> Oops - my bad; it's just LA that're taxing stuff that isn't even on their planet.
If you have any evidence that Andromedans have a corporate base in LA, I think we should be told.
--
rant
How can you be sure that the earth orbit wouldn't be disturbed by ripping up Mars?
--- Hindsight is 20/20, but walking backwards is not the answer.
I think we're in big trouble if another star gets even close to our solar system. Which is a lot larger than just the sun...
We'll be jolted out of orbit.
--- Hindsight is 20/20, but walking backwards is not the answer.
when that system could be predicting next weeks Lotto numbers. Sign me up for an account.
We've got Bruce Willis on standby to go blow it up.
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Sheesh, evil *and* a jerk. -- Jade
Damn! There goes my nightime navigation.
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"All the things I really like to do are either immoral, illegal, or fattening."
"All the things I really like to do are either immoral, illegal, or fattening."
- Alexandar Woolcot
I'll make sure to buy term life insurance.
I keep trying to pick fights, but I can't shake this Excellent karma.
Just blame the police; it was the gravitational force between their car and yours that made you go that fast when they were trying to pull you over.
0x or or snor perron?!
On a brighter note, I bet Natalie Portman really will be petrified by then, so odds are that we'll go out with a meaningful comment on Slashdot.
Spacecraft and satellites are built in cleanrooms not to protect against atmosphere, but to protect against dust and dirt contamination. Dust and dirt will be a part of every human settlement, by virtue of skin flakes and hair if not due to dust and regolith from the lunar surface. So we'll still be building things in cleanrooms for now.
Andrew
It's not surprising that the chance is practically 1 that _one_ star or more will collide. What would be more interesting is the chance that our Sun will collide or not. (Dividing your answer by your 1e11 gives a rather small probability of this).
:)
Your calculation doesn't take into account the size or star density of Andromeda, it assumes stars' cross-sections won't overlap, and it seems to be assuming the galaxies are colliding face-to-face. Also, I read some time ago that the Galaxy's radius was 110,000 light years, so area = nearly 5x10^10 ly^2, ie. 4x10^30km by my calculation.
The galaxy's star distribution needs to be considered too. The galactic centre is _huge_, and probably contains a supermassive black hole. Whichever other stars get in the way of that are gonna be {insert synonym for bad occurrences}.
There's a photo I've seen of two other galaxies colliding (although I forget what they are or which constellation it was). Their edges met at about 90 degrees, and the was a large empty black strip along where they were colliding. Hopefully someone reading this will be able to give an URL or upload their slide
And finally, large gas clouds are no worries to those of us who have had to live with a compulsive farter
the machine that did these animations, the Blue Horizon, is actually one of the top supercomputers (last i checked, 8th). basically a shit load of Power3 (may have since been upgraded to Power 4's). It currently lives at the San Diego Supercomputer Center. more info: http://www.sdsc.edu/Resources/bluehorizon.html
~~~ They call me Little John, but don't let the name fool you...in real life I'm very big.
"The two model galaxies, which eventually merge into one, toss several million stars into the intergalactic void before joining together."
Would be one hell of a ride!
Also... When the sun Goes Red giant.. Are we sure Any of the planets orbiting the sun won't be a million asteroids from collidinnng with some other foreign body in some other galaxy. Or even better. We get sucked into a bigger entities gravity well!!! Whee!!!!!!! I hope we get to orbit a really cool planet like that Roman Planet from the original Star trek. yea!!
--------========+++Dont Feed The Lab Techs+++========--------
I really doubt we could destroy ALL life on this planet. We could destroy lots of it, and ourselves in the process, but not sterilize the planet! And mutating viri are not really a problem for nature! They are to us, but were not really a long term concern for nature!!
Excuse me? What was Fermi smoking?
From SciAM >...If extraterrestrials are commonplace, he asked, where are they? Should their presence not be obvious? This question has become known as the Fermi Paradox.
This problem really has two aspects: the failure of search for extraterrestrial intelligence (SETI) programs to detect radio transmissions from other civilizations, and the lack of evidence that extraterrestrials have ever visited Earth.
Erm..using that logic, we shouldn't exist. Our radio waves are not yet detectable outside of a ~ 90 light year radius and we've never visited another planet outside of our own freakin' solar system...
oops. We're just figments of our.. *poof*
3C
The worsed case would be if the sun passed through the center of the Andromeda galaxy, stars are much closer together there, there is a hell of a lot of ionising radiation there, and a nasty 1 billion solar mass black hole (Galaxy formulation theories suggest that about 1% of a galaxies mass in the central black hole.) Even if the Sun and Earth missed any of the objects in the Galatic core, the Earth might still be cooked and the stripped from the suns orbit.
Oh, my god! A supernova so close to L.A.! How do we save Hollywood? Think of the children! Let's blame Canada.
You can't handle the truth.
It will take that long to get the EU to approve the merger.
For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
I suppose that means that I'll have to change my pension plan and speed up construction of my concrete bunker. Ho humm, busy busy busy
It's easy to say it's not a destructive process when you watch the event from orders of magnitutes of light years away, using the Hubble. But just because it looks purty over there doesn't mean such an event happening to OUR galaxy wouldn't be quite existance-threatening.
Yes, galaxies are mostly empty space. Even still, there would be an uncountable number of collisions.
No, astral bodies don't need to SMACK INTO each other in order to cause major changes in gravitation, orbit, climate, etc.
Migrating to other star systems is a moot point in light of this event. How will populating another system in THIS GALAXY do anything to ensure our survival in an event that affects the entire galaxy?
If we collide with Andromeda, I assure you that the entire structure of both galaxies will change forever, because we don't live in a Newtonian universe. The event won't simply undo itself.
I think you need to read a little Gleick, Briggs, Peat, Lorenz, Hofstadter, Russel, Prigogine, Bohm, or Poincare. They all understand the nature of cause and effect a lot better than you seem to.
Not that I'm trying to sow discord.
There are a number of promising methods of getting information (everything's information, right?) from one place to another faster than the fascist 186k mi/s speed limit. It seems to me they fit into two categories: /. article a while back on this) that "they" are experimenting with this phenomenon to "clone" photons, by using an odd double-entangled procedure. This same article said something to the effect that it violates sumsuch quantum law to pass MEANINGFUL information in this way. I myself don't see how that's possible. I don't understand why a machine cannot be devised that passively measures some effect of the photon's polarity change. This wouldn't violate the integrity of the photon's polarity, because it's only being PASSIVELY measured. Then why can't they use THAT setup to pass digital information across light years instantaneously? I guess I need to look into that.
:) There is a theory floating around (probably has been for some time) that certain naked singularities (black hole without an event horizon, because the singularity spins so fast) that are toroidal in nature instead of spheroidal could mark access points to ERB's because the donut hole would be subject to a whole lot of weird forces. I can't intelligently comment on that, because I don't know how something like that would work. But maybe someone else can elaborate.
taking advantage of common phenomena,
and
finding clever ways to bypass the problem.
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The most immediately promising way to transmit information faster than light is by exploiting the nature of photons. One learns early on in quantum mechanics that photons are very weird creatures. They can become entangled. The exact nature of this relationship is beyond current human capacity to understand, I believe, but it makes for a very convenient situation. Almost a deus ex machina? Anyway, when photons become entangled, they become very self-conscious. They become obsessed with keeping up with the latest fashion trend. They become so obsessed that when their entangled pal changes her polarity, the other one changes to complement the polarity NOT at the speed of light, NOT "extremely fucking holy-shit fast", but INSTANTLY. And to make the situation further seem almost too convenient, entangled photons don't need to be materially near each other. After photons entangle, they can move to opposite sides of the universe and still INSTANTLY complement each other's polarity. Meaning if you change one, the other one changes. Meaning we as humans should be able to devise a system that takes advantage of this nature of photons. I have heard (I am sure most of you remember that
The second method is a little less polite. Speed of light? We don't need no stinking speed of light. The light barrier only applies to space-time. So even a child can postulate that if this odd "space-time" thing is giving us so many problems, why don't we just NOT USE IT as the medium? And I would pat that child on the head, smile, and say, "YOU JUST GOT AN ANSWER FOR EVERYTHING, DON'T YOU, YOU LITTLE LOUDMOUTH SHITHEAD?!" But I digress. That's the basis behind the Einstein-Rosen bridge (you know it from Contact, Event Horizon, and probably lots of other movies that don't cross my mind now). Basically it goes that since our space and time are pissing us off with these heinous limitations, we can just create our own alternative kind of space that connects two definite points in space and time. This alternative kind of space and time is not stable enough to use as a parallel universe, and though there are doubts that physical matter could pass through it and still remain intact, we're MARGINALLY sure that electromagnetic radiation could pass through it with an acceptable loss. So I guess that means that wormholes are lossy transportation protocol
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As always, come and point out my stupid mistakes.
What, me worry?
I remember as a kid learning that the Sun was going to go red giant in 5 billion years or so. My first thought was "But we are swarn to protect the national parks!"
Now in addition to moving the planit far enough away from the sun to protect the parks we now have to move the Milky way on top of that. O bother.
Ascii artist &
Numerically.
Funny thing they used a supercomputer, no?
(What's that? You wanted an analytic solution????)
This feels just like that real-time trip to Alpha Centauri computer game. Can't we do a fast-forward on reality?
Money for nothing, pix for free
I was just about to post a reply asking you to explain what you meant, but I was suddenly enlightened.
You're right: Stuff is cool.
...And people complain that Slashdot never has anything cheerful to say...
He put his boots up on the table and made a face. "The sig," he smirked. "You can waste your life in search of the sig."
all objects closer to another but because of their speed, I doubt many will actually collide
I'll cite that when I get pulled over by the police for speeding again.
The distribution of galaxies throughout the universe is not uniform. This clumpiness results in regions where local gravitational interactions dominate local kinematics.
In general, though, we see other galaxies as red-shifted (receding). Things tend to get more interesting at smaller scales (for Chinese values of interesting).
In 3 billion years, I figure we'll have a way to create a force field around our galaxy. Screw those prissy Andromeda folks one last time. -- ksheka
alias uptime="echo '5:33pm up 22342352324 days, 6:28, 2124315623 users, load average: 2432.40, 12312.31, 123123.19'"
Actually from the look of the simulation and knowing that the terran system is on the edge of the galaxy, it looks like *we* will be leaving after the third inning or so. Really what's the point of staying? It's all rigged anyhow.
Please be patient, I'm a work in progress! --Alan Jackson
Don't you mean (1 - 8.3e-19) ^ 1e11? I mean, assuming each potential collision is an independant, random event.
:-).
Yeah, that's true, but it didn't fit on my calculator, so I gave a reasonable approximation. And the collisions are not totally random, but I'd hate to do the math on that (that's why we have supercomputers, right?
But the sight will be something, provided you are on a dark enough spot (remember, in most populated places you can even see the milky way due to scattered light, and that's the galaxy we're in!)
- Mute
- Kite
`But gravity always wins.'
- Radiohead
If we don't begin to migrate to other planets and other star systems soon, we'll be doomed. Overpopulation, biological warfare, mutating viri.
Maybe we should actually first solve those problems with humanity that are dooming us (tendency to overpopulate, kill each other, play with overly destructive weapons, etc.) before we take our shit to other planets and ruin them too.
I think if aliens have been around here and seen us, they probably haven't officially contacted us because they realized we're a big bunch of destructive assholes. I bet they'd be interested in stopping us from spreading to other planets. :)
How can two galaxies collide!!!!
Truth: If it's not one thing, it's another
This is a very interesting question. No one seems to be able to get their stories straight regarding the Big Bang theory and evolution theory itself. For example, the galaxies wind themselves up too fast - they could only be a few hundred million years old. A good book on some of these issues is Starlight and Time by Dr. D. Russell Humphreys - ISBN: 12027
You're going to move enough resources to the moon to fabricate satellites from the Moon's raw materials, and this is supposed to be an energy savings over sending up a simple satellite? Get a grip.
- Sig this!
Somebody let Alex Chiu know about this!
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This is true, but you're forgetting that Andromeda can make the Kessel Run in under 12 parsecs.
Somewhere, something incredible is waiting to be known. -- Carl Sagan
Hey! Great news for the poeple at the Dark Sky Association. Besides, if I want to look at something grey and lumpy in the sky, I think they should just start throwing old people out of airplanes. Hey that solves the United States' Social Security problem too!!
Smeghead every day of the week.
Courtesy - Image Google
OK:
Make Galaxy^2 is 4 days on a Supercomputer.
Now, Make Universe is...
It takes 40+ muscles to frown, but only four to extend your arm and bitchslap the motherfucker
Actually, due to tidal forces between the earth, moon, and sun, before the moon escapes Earth orbit, an Earth day will exceed a month in length, and the moon will begin to approach the earth again. So theoretically, we won't lose it.
well, if he put the initial tools on the moon, then perhaps he could mine an asteroid. with ne perpultion methods making it feesable to travel to mars in only 2-3 weeks, then the asteroid belt would be a feasable target as well. we could launch the space craft crom the moon, harvest material, bring it back to the moon, mill it, and use it to build more stuff, and to send back to earth.
I am the Alpha and the Omega-3
after the whole china incident, i doubt that the big bad bush would have a problem if he was allowed to control "foreign bodies". ha. haha. *hackcoughdie*
Living on planetary surfaces is actually more costly than building space habitats--using current, not "thousand years" off, technology. And, yes, instead of living on Mars, we could (and probably WILL eventually) rip it apart and spread the material out more efficiently, creating a vastly greater surface area to live in comfortably. Leaving Mars, and the other planets alone, there's still enough asteroidal material to support a *million Earth populations (*I forget the 'exact' estimate, and am too lazy to look it up right now).
Power to the Peaceful
There's no future in living on the limited surface area of a select few habitable planets. However, there *is* a future in building our own habitats in freespace; and they'll be able to support populations millions of times larger than any Earth or Mars could.
Power to the Peaceful
What's the use of the truth if you can't tell a lie sometimes?
Sun will be a red giant in about 15 billion years, and its size will increase dramaticaly beyond the Mercury orbit
Does this mean I should buy a lot of SUNW stock?
Healthcare article at Kuro5hin
Given that life on earth has evolved under the influence of the Moon, that may be more serious a problem than most people would imagine. I wonder how many species depend upon the tides for their survival?
Ok, I'm mathematically ignorant but I'd like to know more about how they simulate these things -- in an educated layman's terms. Wouldn't two galaxies colliding be the n-body problem from hell?
It is somewhat of a deal actualy. While the stars themselves don't actualy collide, the dust and gas contained within the galaxies do.
This causes large numbers of new stars to be formed. New stars emit large amounts of hard radiation. Furthermore, many of the new stars are quite massive and soon explode into supernova, providing large, powerful radiation blasts.
How would this affect us? Any sufficiently close supernova would most likley be powerful enough to ionize the entire earth's atmosphere, wiping out all life here.
here's a picture of a starburst galaxy
This is from the article you link to: Paul Horowitz of Harvard University, has stated that he expects at least one radio-transmitting civilization to reside within 1,000 light-years of the sun
I bet there is at least one... Us!! Duh
Your sig should be attributed to A.C. Clarke, not Issac Isamov. (Due to the nature of sigs on slashdot, if you fix this my comment will look weird because the fix will appear retroactively in your post, but hey, I can live with that.
Don't label something "offtopic" unless you know the topic well enough to tell what's on topic.
How does a galactic collision affect planets in a galaxy?
Consider a single star, not in a galaxy, with a planetary system like the sun. Nice and stable. But if it should be heading for a galaxy, what are the chances of it passing through without gravitational forces disrupting the planets?
Interstellar separation may be large compared to stellar radii, but if you pass through enough stars there's an increased chance that you come near enough to one to affect the planets. Maybe.
Baz
This event will completely overshadow the release of kernel 388472466124525.27324.212
I am sure everyone will forget to update their kernel when the galaxies collide.
On a less humorous note, has anyone read that a scientist claims that the Earth can be gradually moved away from the Sun, using the gravitational force of a comet? The side effect will be that we may lose the Moon in the process...
http://www.space.com/scienceastronomy/planetearth/ earth_move_010207.html
The side effect will be that we may lose the Moon in the process
That would be nothing short of a disaster. I remember seeing a documentary on TV a couple of years ago where they showed that it was the gravitational pull of the moon in its particular orbit, that holds earth's axis in place. Thus stopping the spin of the earth from upending the poles or placing them somewhere completely different. We'd suffer terrible climate instability if the moon didn't exist where it does, and it's possible that life might never have developed here at all.
Macka
I'm pretty sure it's estimated the sun will burn out and become a red giant in about 4 billion years.
All you people working on infinite lifespan projects might as well hang it up now. Just 3bil years is hardly worth it now is it?
You never really know how close to the edge you can go until you fall off.
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"Of course, that's just my opinion. I could be wrong." --Dennis Miller
Of course, in 3 billion years, this might not much matter, but for two colliding galaxies, its quite possible for both of them to pass through each other without any stars colliding. However, its extremely likely that one or two stars will come within a light year of Earth. What will happen is a lot of the debris in the Oort cloud which usually remains in long period orbits way way out there can be flung into the inner solar system (the same effect happens every 60 million years or so when the solar system passes through one of the spiral arms.
:)
When this happens, there are suddenly a lot more big rocks roaming around the inner solar system, and the chances of Earth getting hit by one of them increases dramatically.
Of course, I personally don't plan to lose any sleep over this.
-Restil
Play with my webcams and lights here
Both galaxies have lot of void space. Only here and there an object can be found so there's not much chance for real collisions. Off course gravite will pull all objects closer to another but because of their speed, I doubt many will actually collide. Can anybody give an estimate of how many objects will actually collide and what this means for live on earth?
0x or or snor perron?!
Really nice guy, too. In '93 I wrote him a letter and asked him what the status of the Nemesis Hypothesis was, and he wrote a very nice and thorough reply in which he indicated that Hipparcos, a satellite which was supposed to resolve it once and for all, suffered an instrumentation failure. They were falling back to a manual sky-search and were hoping to have it done by 2000.
Given that it's now 2001 and we haven't heard anything, I think we can conclude either
- The search is taking far longer than expected
- Fundamental problems in the search methods kept it from being a productive observation
- The search was concluded and nothing was found, and Nemesis is pretty much a dead theory
... That being said, Richard Mueller is a very serious scientist. It angers me when I hear people call him a kook for the Nemesis Hypothesis (not that the original poster did).The Nemesis Hypothesis was classic scientific work. It was a blindingly creative look at a very difficult problem. It explained past observations and made predictions for future observations. The hypothesis was, is, testable (admittedly, not easily testable).
Compare this to superstring theory, which has no observational support, no experimental support, no predictions for future observations. While I like superstring theory--it's a really cool thought exercise--it's not science.
So why is it so many hail Brian Greene (superstring theory luminary) as the next Einstein, and in the next breath condemn Mueller as a kook?
It's just like how two cars can collide despite the expansion of the universe. Our two galaxies are not big enough or distant enough to be affected by the large-scale expansion of the universe. Other effects are much more significant at these small scales.
--
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
Sun's gonna go Red Giant in 5 billion years, not 15.
Picky picky picky.
--Nuintari
slashdot : where an opinion can be wrong.
I wonder if my collision insurance from State Farm covers galaxies. Which driver would be at fault?
I'm trying to teach myself to set people on fire with my mind... Is it hot in here?
Arthur C. Clarke
Because typical distances between objects in the universe (such as superclusters) are a lot Lot LOT bigger than the measly 2,300,000 light years between Milky Way and Andromeda.
The expansion of the universe means things which are already very far apart will get farther apart -- "the rich get richer...". It has miniscule effect at the level of individual galaxies, where gravity is firmly in charge.
You should now feel a whole lot smaller than you did a few minutes ago. On the bright side, you're still way bigger than quarks. :-)
Note that you're using the word "soon" in conjunction with an event 3 billion years from now. It seems to me that if we can get a self-sufficient Mars base within the next thousand years, and colonize other solar systems within the next million years, then we're way ahead of the game.
Overpopulation, biological warfare, mutating viri.Overpopulation is generally self-correcting (starvation). It's also easily handled by public education and women's rights (see western europe). And as for biowar/mutation, I have justified belief in medical progress and the human immune system.
Will Mozilla be finished by then so people can watch the live webcast?
Oops - my bad; it's just LA that're taxing stuff that isn't even on their planet.
Anyone interested in this should really check out the book The Mote In Gods Eye by Larry Niven and Jerry Pournelle. Mankinds first encounter with an alien species is with a species in much the situation described above. They can't efficiently get out of their solar system, which has led to all sorts of changes in their society, biology, traits, etc. Makes for an excellent read.
Just as water vapour moving very energetically in clouds produces lightning, I would imagine that colliding gas clouds would cause a lot of unimaginably intense electric charges.
These clouds are also a plasma similar to the inside of a fluorescent tube, so the lightning would cause very intense bright flashes.
Imagine the night sky being lit up by hundreds or thousands of bright flashes.
Dude, that's like saying, "Your going to spend all this time and effort building this huge Widget factory, when you can just carve Widget's out yourself?". Yes, of course there is a high up-front cost, but it's made up for in the long run. Economies of Scale, hello?
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True enuf, although I suppose the article cannot get everything right.
Time to get out the 5000 rated sunblock
;-)
Check out the Vinny the Vampire comic strip
"It is a greater offense to steal men's labor, than their clothes"
I'm going to have to start taking bets on the outcome
Check out the Vinny the Vampire comic strip
"It is a greater offense to steal men's labor, than their clothes"
Why are they using the Startrek font on that "Quicktime" mpeg? Are they trying to get some funding for an escape plan?
Good thing that galactic spirals aren't due to winding, then, isn't it?
An excellent online reference on density waves (the phenomenon currently thought to be responsible for the appearance of spiral galaxies) is at http://fuse.pha.jhu.edu/~danforth/spiral
Density waves were proposed in the mid-60s and have (so far) stood up pretty well. What this has to do with the big bang or evolution is beyond me.
5 Gy is the rule of thumb figure. I even just asked a passing solar physicist about it... :-)
Employee of Inrupt, Project Release Manager and Community Manager for Solid
As a layman, I would have thought that all galaxies would be moving generally away from one another.
Then again perhaps I'll catch that ride on one of those Vogon ships .. which reminds me ... plenty of time to invest some cash in a towel company..
--
Jon - TheSpork
I thought that was about 8 billion years? Anyone?
This is indeed highly cool and it's nice to see some astronomy on /. ... it's now comonly accepted that our galaxy has already borged many smaller less-fortunate ones in the local group; shreds of their corpses (I'm not making this up! have been located in our galaxy by looking for stars with anomalous motions, ie fossilised fragments of things we ate long ago.
Thing that gets me is, given that the Sloan Digital Sky Survey just found a quasar at redshift 6.2 (ie about 10 billion years old)... this is getting pretty close to the Big Bang... this doesn't give much time for our galaxy (or any others) to actually form, before we're switched on, full of stars, and eating our neighbours.
The more I write, the more this sounds like some sick geek in-joke... [*1 10 points if you spot the reference
--
"I'm not downloaded, I'm just loaded and down"
Every day the sun gets hotter and in a little under one billion years the earth will be too hot for life as we know it. My suggestion would be start snapping up that cheap Mars real estate right now. It's always best to get in on the ground floor for the best prices.
Smeghead every day of the week.
In another 3 billion years, according to moore's law, our processors are going to have enough transistors to attract nearby galaxies just by turning on. i bet that didnt go into the particle field.
I am trying to quit smoking
Someone call our galaxy's insurance agent, and be sure to get some
photos of the accident. I'd sure hate to be stuck with the
repair bill on this one.
I assume that's at least marginally more accurate than the screen saver that comes with my Linux distribution, eh?
Seeing this woke my curiosity...
;)
How carefully and realisticly can they predict all this? It must be very close to a chaos-theory if you ask me, *EVERYTHING* affects *EVERYTHING* and here they are saying what's going to happen in 4 billion years - bold.
Of course people can guess and make it a good guess at that but really, how much time and knowledge have been put into these simulations. How much do we know about the world/universe around us to accuratly predict "so and so will happen..."? Is everything just based on what we know every starsystem looks like and it's position or is there more stuff to back it up?
And besides, who cares? I'm long gone when these 3.9999999999999999 billion years has passed
Anataka suki desu. Itsumo. Itsumademo.
See the rather tasty java applet by Leonardo Boselli, Galactic Collider 1.0, which shows how spiral arms are created when galaxies pass close by each other. You could change the start positions to whack two galaxies together, if that's what you really want to do...
The child's site you point to correctly points out that the sun will * burn out* in about 5 billion years, however, it will turn into a red giant about a billion years before that.
As for the 15 billion figure that is the estimated age of the *entire frikkin' universe* so I guess the author should get credit for having been able to attach a cosmological number with a subject of cosmology, but it's kinda like saying that Lincoln was assasinated in 1066.
KFG
One statement there says "the gap is closing at 500000 km/hour". I am not a professional astronomer, but I understand that we can not currently determine the proper motion of objects farther away from us than a few tens of light years. So although we know that Andromeda and the Milky Way are hurtling toward each other at 500 thousand kilometers per hour, we do not know how fast they are moving with respect to each other in the sideways direction. It is highly likely that the proper motion component of the relative velocities is greater than zero. If there is a high enough proper velocity, this would mean that the two galaxies, being in orbit about a common point, would miss when they came to their closest point and just fly right by each other.
The article touches on this with "the best explanation is that the Milky Way and Andromeda are in fact a bound pair of galaxies in orbit around one another." But they make no reference to the unknown proper motion.
Also, it is possible that the galaxy we live in now may well be the result of a historic collision of two smaller galaxies. The evidence for this is that the Magellinic Clouds are now in orbit around the Milky Way and are irregular. Now, this is speculation on my part, but that's allowed, isn't it.
A few years ago, astronomers announced that a dwarf galaxy in the direction of Saggitarius was colliding with the Milky Way. I'm not sure it's exactly within our galaxy's borders [I'd thought it was, but the only reference I could find after a minute of googling said otherwise], but it's orbiting (every billion years or so), and the galaxies have had an effect on each other. Check out this FAQ about the dwarf and the referred page. Key quote: "It [SagDEG] is apparently in process of being disrupted by tidal gravitational forces of its big massive neighbor in this encounter. "
xlock -inwindow -mode galaxy &
:)
Bowie J. Poag
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Mod up a post Rob doesn't like and you'll never mod again
Galaxies collide all the time. It's not a real destructive process. Look at the distance between stars. A "collision" of galaxies is like the collision of dust particles in a wind. There are very few stars that actually come into contact with each other, it simply increases the mass of the galaxy as a whole. We add a lot more stars to the galaxy and that's pretty much it.
Never mind the fact that, unless we start to migrate to other star systems in the next few hundred years, there's little chance that any of our descendants will be around to see it.
We're at a very delicate time in the history of our race. If we don't begin to migrate to other planets and other star systems soon, we'll be doomed. Overpopulation, biological warfare, mutating viri. All these things can lead to the destruction of all life on this planet. Then there are the less likely scenarios: Asteroid collisions, comet collisions. These too will happen, it's just a matter of when.
But the actual collision of the galaxies, as I see it, is just another opportunity for us to have more planets to colonize.
It also raises the possibility of us finding other life out there.
Scientific American ran a great article here about how the chances are, we're the most advanced species in our galaxy and why. It makes a great deal of sense. A collision with Andromeda could change that, and that I find interesting. Especially given the time frame. If we're to migrate through the galaxy, we could be in very good shape if Andromeda itself is already populated.
But I'm just wandering off into all kinds of stuff completely unrelated. Sorry... I love this stuff, though.
solving the ODE's is done numerically.
the main problem is of calculating the force on every star at every iteration.
the problem was thought to be quadratic , but a decade ago was shown to be linear (by a PhD student named greengard) using spherical harmonics expansions.
a very nice layman's introduction is at:
http://www.amara.com/papers/nbody.html
there are other sources linked there as well.
keywords:
N-body problem
Barnes-Hut algorithm
Fast Multipole Method (FMM)
BTW I wonder what method they used, my guess is that at 10^8 stars an adaptive FMM variant is fastest.
Working for necessity's mother.
Galactic collisions are actually relatively common in Nature; typical galactic separations are of order hundreds to thousands of kiloparsecs (kpc), whereas a typical galaxy is of order a few kpc in radius. Moreover, galaxies form along a highly filamentary spiderwork of structure in the early universe, and tend to flow inwards to more massive galaxies.
This situation is to be contrasted with the fate of stars during a galactic collision. Stellar radii are about 10^8 times smaller than the typical interstellar separation, so the vast majority of stars will simply fly right by another. A few stars will probably encounter a direct encounter (particularly if the initial pass is close enough to raise subtantial tides on the stars, which would act to drain energy and angular momentum from the system), but the vast majority fly by unscathed.
It is true, however, that gaseous clouds in the interstellar medium are much more extended that stars, and collision between clouds (particularly giant molecular clouds) will be quite spectacular. It is hypothesized that cloud collisions as well as gaseous flows (bringing tremendous influxes of mass to the galactic nuclar region) resulting from galactic collisions can account for the tremendous bursts of star formation seen in "starburst" galaxies such as NGC 1808.
In any case, the future collision of the Milky Way with Andromeda will be quite fascinating for far future Milky Way astronomers (if any are still around). Or perhaps for astronomers in other galaxies, far, far away...
Bob
Science, like Nature, must also be tamed, with a view turned towards its preservation.
3 billion years, eh? That ought to give California plenty of time to figure out how to tax Andromeda.
Look, there's no point in acting all surprised about it! The plans for the destruction of the Milky Way have been up at your local planning office in the Lesser Magellanic Clouds for the last one and a half Hubble Times so there's no point complaining now! I don't know, stupid bloody apathetic Galaxy, I've got no sympathy at all!
Phear my l33t homepage.
"A lof of people know that our Sun will be a red giant in about 15 billions years, and its size will increase dramaticaly beyond the Mercury orbit and we will burn. " Who needs demotivators?