

Scientists Complete Universe Millennium Simulation 375
james tech writes "The Virgo Consortium recently completed its massive "Millennium Simulation", tracing the universe's evolution from its early origins to present day. To simplify the computations, they considered only dark matter which composes most of the universe. Using a 512-node cluster with IBM processors, the group produced over 20 terabytes of data with some of the most breathtaking images of the universe never seen. A visible matter simulation is underway, at a lower resolution."
impressive (Score:4, Funny)
Re:impressive (Score:5, Funny)
Well, rumor has it that... (Score:5, Funny)
Re:impressive (Score:3, Funny)
--Rob
Total Millenium Vortex (Score:4, Funny)
Re:Total Millenium Vortex (Score:3, Funny)
You're welcome.
Mod parent up Insightful (Score:2)
Re:Mod parent up Insightful (Score:3, Insightful)
Dark matter is "observed" indirectly through gravitational effects. It is not that the scientists doubt its existence, it is just that they cannot observe it directly, hence the name "dark".
A crude example would be if you were looking out your window at a lake. You might see waves caused by fish swimming below, but you would not be able to describe the fish, because you only saw the wave.
Talk about bloat (Score:5, Funny)
Re:Talk about bloat (Score:5, Funny)
Caveat -- cosmology not far from understood (Score:5, Insightful)
I feel that this quote is appropriate, as I believe this type of simulation possibly cannot contain every essential physics that governs the evolution of the Universe. Some oversimplification must be present and some tweaks (e.g. dark matter) may go into the modeling to match whatever we see it today.
This isn't the end of the study of cosmology. That's all I'm trying to say.
Re:Caveat -- cosmology not far from understood (Score:2)
Re:Caveat -- cosmology not far from understood (Score:2)
This combines the largest simulation of the growth of dark matter structure ever carried out with new techniques for following the formation and evolution of the visible components. We show that baryon-induced features in the initial conditions of the Universe are reflected in distorted form in the low-redshift galaxy distribution, an effect that can be used to constrain the nature of dark energy with next generation surveys.
Re:Caveat -- cosmology not far from understood (Score:3, Insightful)
Yeah, this could be proven to be utterly wrong in 5 years; or it could be used as a benchmark study for the cosmological study of large scale structure. The community will decide that sooner or later.
Re:Caveat -- cosmology not far from understood (Score:2)
Yes, but as a source of desktop backgrounds (ignoring the impending /. effect) it can't be beaten
Re: Caveat -- cosmology not far from understood (Score:5, Insightful)
> > "It doesn't matter how beautiful your theory is, it doesn't matter how smart you are -- if it doesn't agree with experiment, it's wrong." -- R.P. Feynman
> I feel that this quote is appropriate, as I believe this type of simulation possibly cannot contain every essential physics that governs the evolution of the Universe. Some oversimplification must be present and some tweaks (e.g. dark matter) may go into the modeling to match whatever we see it today.
Yes, and figuring out why your model doesn't reproduce what you see is where the potential for real discoveries lies.
Re: Caveat -- cosmology not far from understood (Score:2)
I'd say many predictions are crazy nonsense. Here's a prediction on tomorrow's weather: It's going to rain.
I'm correct aren't I? I just didn't say where. Okay, a less smart ass reply: It's going to rain in Sydney. Am I right? Am I wrong? Who knows. If I'm right, I can say I've got a predictable model, if I'm wrong, I can say "hey, I'm not always wrong." I'm sure the model they use is better then mine, but it's easy to create a model tha
Re: Caveat -- cosmology not far from understood (Score:3, Interesting)
People get information about the current weather using weather balloons, satellites, everyday weather instruments and whatever else. Then they can use that data to pretty accurately predict what's going to happen next. If you see a bunch of hot air, clouds, cold air, you know where winds are coming from, the temperature of them, the speed, etc. and you know from past experience what
Re:Caveat -- cosmology not far from understood (Score:3, Interesting)
The best we can eventually hope for is a comsological model that agrees wit
evidence (Score:5, Interesting)
Re:evidence (Score:5, Informative)
Re:evidence (Score:5, Informative)
Since the amount of matter is measured to be around 25% this means dark matter must be around 20% of the critical density.
Incidentally, this also means that 75% of the energy/matter in the universe is 'dark energy', since the cosmic microwave background indicates the universe is almost exactly flat.
However, the importance of each constituent changes over time because essentially the dark energy is proportional to the size of the universe and when it was much smaller the matter was more concentrated so it had a far greater influence. Therefore for studies of the early evolution of the universe the dark energy is unimportant, and since dark matter is most of the total matter the models can just use dark matter alone. At present, however, the dark energy appears to be causing an acceleration of the expansion rate, which is seen using distant supernovae. This is how the 75% figure is worked out.
NB: Nobody can explain what the dark matter or dark energy is right now! This is by far the most important problem in Cosmology, and there are many , many competing theories.
Re:evidence (Score:3, Interesting)
Also, recently some structures of the higher energy band of the background radiation are suspected to be the result of the decay-series of those weakly interacting particles, as predicted by the theory of supersymetry.
http://arxiv.org/abs/astro-ph/0405235 [arxiv.org] (sorry for the plug
Counter-evidence (Score:2)
It is surely more absurd to insist that all the matter in the universe interacts by the electromagnetic force, than to suggest that a sizable proportion does not.
Re:evidence (Score:4, Interesting)
I looked into that whole thing. Most of the people who make that claim refer to Keplers laws of motion for orbiting bodies. If you assume the stars orbit a heavy core and don't interact with each other you get a galactic rotation curve that tapers off with radius. Real measured curves are nearly flat, so they conclude some "dark matter" that has some really unintuitive properties (see below). My own calculations of a rotation curve for a uniform flat disk of stars using interactions between all stars shows velocity increasing roughly linearly all the way out, and increasing even faster toward the edge. I don't think we should be suprised that observation lies somewhere between these two models. My distribution of stars is not accurate.
Stupid properties of dark matter: The interaction with regular matter must be asymetric. Why? Because they model it as a sphere of dark matter enclosing a disk shaped galaxy to get the expected rotation curve. If dark matter interacted with itself and visible matter in the same way visible matter interacts with itself, they should have the same distribution. I think they just observed that a big sphere of stuff would make their flawed model match reality and said "oh there must be this goofy thing here". Remember, there are NO direct observations of dark matter (or energy).
The tragedy of Einstein is that he convinced physicists that strange nonintuitive things are a part of the universe. This encourages the promotion of nifty off-the-wall sounding theories that make headlines to get funding.
I've said it here before: The only dark matter is between the astrophisicists ears.
Re:evidence (Score:4, Insightful)
This argument has several flaws. There is direct evidence for dark matter in the cosmic microwave background data, which is why dark matter is now the preferred theory for explaining galactic rotation rates.
It's not actually the theory that all of the "normal matter" in our galaxy is visible in a disk, and all of the "dark matter" is distributed in a sphere - a significant percentage of the dark matter in our galaxy is thought to be normal matter that just didn't clump enough to form (many) stars - that is, disperse hydrogen gas.
For the remaining "exotic dark matter", the one thing we know about it (from the CMB data) is that it interacts weakly with normal matter. There's no reason to assume that whatever caused most "normal" matter to clump and eventually become stars would cause "exotic" matter to have a similar distribution. A disk makes sense for matter that tends to form clumps as a result of collisions, and a sphere makes perfect sense for matter that doesn't. It's not all that unintuitive or surprising, given the data now in hand.
Re:evidence (Score:2)
I believe Big Bang is the outcome of the observed
RedShift. Dark Matter is the outcome of trying
to fit the rotation curves, and Gravitational
Lensing. It is also used to fit the data for
structural formation of the observed universe.
But these all could be due to the same lack of
understanding of the basic laws as applied to
large distances.
Big bang (Score:4, Funny)
Apparently all the packets on the internet condensed in one of their servers and created a second universe, from now on to be referred to as "cyberspace".
Comment removed (Score:5, Funny)
So that is where all the money goes... (Score:2, Funny)
Mirror to full text (Score:2, Informative)
MirrorDot (Score:4, Informative)
About those authors... (Score:4, Funny)
> Authors: Volker Springel (1), Simon D. M. White (1), Adrian Jenkins (2), Carlos S. Frenk (2), Naoki Yoshida (3), Liang Gao (1), Julio Navarro (4), Robert Thacker (5), Darren Croton (1), John Helly (2), John A. Peacock (6), Shaun Cole (2), Peter Thomas (7), Hugh Couchman (5), August Evrard (8), Joerg Colberg (9), Frazer Pearce (10) ((1) MPA, (2) Durham, (3) Nagoya, (4) UVic, (5) McMaster, (6) Edinburgh, (7) Sussex, (8) Michigan, (9) Pittsburgh, (10) Nottingham)
Now you know why "et al." is one of the most important concepts in the natural sciences.
Seems like a waste of time (Score:2, Insightful)
Sorry, but this reminds m
Re:Seems like a waste of time (Score:2, Insightful)
Re:Seems like a waste of time (Score:2)
Amazon didn't get a single patent on Einstein's watch. That alone should get him a B+.
Yes, I'm replying to a .sig; mod me like I endorsed a M$ product.
Re:Seems like a waste of time (Score:2)
What, with the cynical slashdot crowd?
Re:Seems like a waste of time (Score:2, Insightful)
a new model, with better clustering, better arithmetic, better data mapping, we get an improvement in modelling technology and its applications. Very little separates 90% of the software in this example from the modelling used for DNA modelling in medical sciences or the massive tensor arrays used for climate modelling.
I agree many theoretical physics stuff seems pie
Re:Seems like a waste of time (Score:3, Informative)
All models are oversimplifications. Even our models of molecules pretend that atoms are solid spheres... This doesn't mean that the models are useless.
That said, only time will tell how useful this model is.
Re:Seems like a waste of time (Score:2)
Rather than disagree with your analogy, let's add a time-condition. It's like finding a drawing of Michaelangelo's "The Adoration of the Magi", done in green crayon that was executed on a cave wall sometime in the paleolithic. Now that's impressive. Our scientific cosmology is still in
Backwater journal you say? (Score:2, Insightful)
Well, if you considert "Nature" a backwater journal, then i dont know.... where should i publish? This paper went through a peer-review process, so its not just pretty pictures.
Although, I am partial to agree that simualtions are approximations, how long should we wait then before we attain "suitable" computing power? Everything starts somewhere.
Re:Seems like a waste of time (Score:5, Insightful)
I've done some work in the past couple of years on simulations of galaxy collisions, and can speak a little on the value of this type of research.
Large-scale structure simulations such as this one do have specific uses. They do not claim to reproduce the current universe in all its complexity, but can be used to test theories on its composition. When doing simulations like these, one makes certain assumptions in order to test them. They seem to have assumed that dark matter is made of non-relativistic (cold) particles that only interact gravitationally. They also would have had to assume an initial distribution of dark matter that has small density fluctuations. So by comparing the results of this simulation with observations of the real universe, one can get an idea of how accurate our theories of dark matter behavior and initial conditions are.
A common theory that is often assumed to be true is the Cold Dark Matter (CDM) cosmology, where all dark matter is assumed to be relatively heavy particles that are moving much more slowly than the speed of light. When you do this kind of simulation, a large number of dwarf galaxies are created, several times more than are observed in the real universe. This is a strong indication that the CDM assumption is flawed, that there is at least small portion of the dark matter that is "hot", or relativistic, as if there were a large number of high energy neutrinos, or some similar particle.
Re:Seems like a waste of time (Score:3, Interesting)
Re: just because we can. That's the greatest and best reason to do anything.
I think you make a salient point though, in that the publication of such preliminary research tends to be injurious to the general public..
Typical (Score:5, Funny)
Reminds me of a joke:
A rich oil-baron hires a veterinarian, a statistician and a physicist to develop a method for predicting the outcome of a horse race. The three scientists disappear for a week and each returns with a different method; The vet states "I have studied the form, health and blood-lines of all the horses for the next race and can confidently say that number 7 is the best of the lot. Whether he wins on the day, is another question". The Statistician boasts "I have studied the race histories of all the horses in the next race and all the races ran on this track and can definitely say that horse number 3 has a 85% chance of coming in the top 3". The physicist then strides up to the baron and boldly proclaims "I have developed a way to predict the outcome of any race with 100% accuracy! First, one assumes that the horses are perfectly spherical and moving through a vacuum...".
Re:Typical (Score:5, Insightful)
I generally find that joke is found to be funny in direct proportion to the audience's scientific illiteracy. "Har har, look at those silly scientists, spouting their nonsense. I'll just sit here and laugh at them while I enjoy all the lovely modern technology their work has made possible."
While mildly amusing, it betrays a deep failure of understanding the value of analytical simplification. Just because something sounds silly to the uninformed does not mean it has no value.
As pitiful as the current public understanding of science is (as evidenced by such things as the rampant belief in nonsense like 'creationism'), it'd be nice if the problem not further exacerbated.
Re:Typical (Score:5, Insightful)
It's an exaggeration for comic effect. Every good scientist recognizes in it some silly oversimplification he or she has made at some point in the past, because that's the way science gets done. The nonscientist doesn't get it precisely because he doesn't know how science gets done.
Public misunderstanding of science has little to do with the jokes of scientists poking fun at themselves. In fact, one of the best ways to convince the general public that science is simply wrong is to be humorless about it. Lighten up.
Re:Typical (Score:2, Insightful)
Suffice it to say it sounds funnier the less you actually understand the subject matter. It has a very shallow perception of the subject; someone who actually knows the material is more likely to think "wait, that's not how it works..."
Have you ever seen technology-oriented jokes of the variety that poke fun at how difficult simple electronic devices are to use? The whole "haha, the power
Who is to say... (Score:5, Insightful)
Re:Who is to say... Tipler/Physics of Immortality (Score:2)
Re:Who is to say... (Score:3, Funny)
If I had a dollar for every stoned college kid that thought of that and exclaimed, "Whoa, dude," I'd have enough money to buy a supercomputer capable of simulating an entire universe of stoned college kids wondering whether they were in a computer simulation and exclaiming, "Whoa, dude."
Re:Who is to say... (Score:2, Interesting)
It would be cool to imagine that during the above experiment, in what for us seemed a few days, an entire universe came to be, evolved and faded away.
Re:Who is to say... (Score:4, Insightful)
Actually, I-D does preclude evolution (at least macro evolution). I-D proponents claim that complex structures (they love to pick on the eye and protozoan flagella) must have been designed, and could not have evolved. Many try to bastardize the concept of entropy, and claim that complexity arising out of less complex structure violates the laws of Physics. If you try to posit complex structures coming into existence through evolution, then you remove their entire argument for I-D (watch needs a watchmaker).
There are many people who believe that a god created the Universe, and created life, but then that life evolved into the diversity that exists today. This is not I-D.
TORRENTS needed! (Score:3, Informative)
The video I got was pretty impressive at 1024 full screen mode. I haven't been able to get the other one.
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See Also... (Score:2)
title? (Score:2)
100Gyr (Score:3, Insightful)
Re:100Gyr (Score:2)
Its because they absolutle exacly know what is going to happen, simply because of the choice of starting parameters of their simulation.
But as their is no reality to compare with (for those future), there is no scientific value to it.
Suspicious (Score:3, Insightful)
Re:Suspicious (Score:2, Insightful)
If this simulation is useful in any way for building new theories that are in turn useful for predicting other things, then it isn't a loss.
Even if the simulation is complete bunk, as long as it is studied and reasons are articulated why it is complete bunk, then it wasn't a loss then either, we then know how not to do such a simulation in the future.
Re:Suspicious (Score:2, Insightful)
While the simulation in question makes huge sweeping simplifications (including the amusing--if reasonable--omission of the relatively insignificant contribution of visible matter), it seems to be based on cosmological physics that have been thoroughly tested and produce reliable predictions. The more speculative stuff doesn't really even enter into it.
Besides, the purpose of a simulation like this isn't to be accurate
The simulation... (Score:2, Funny)
Currently slashdotted (Score:2, Informative)
Suggest people who want to see the pretty pictures use the Mirrordot mirror link at
http://mirrordot.org/stories/bdfc0ad7cef604a1af6b
Re: (Score:2)
So, to quickly simulate everything that exists... (Score:5, Funny)
Yay!
Re:So, to quickly simulate everything that exists. (Score:2)
But they can't run it into the future... (Score:3, Funny)
Here they come (Score:2, Funny)
google maps link to server beeing /.ed (Score:2, Interesting)
And the Answer is (Score:4, Funny)
Ok, Let me get this straight... (Score:5, Funny)
Breath-taking images of *DARK MATTER* ??? WTF
Dark Server (Score:2)
Torrents (Score:2, Informative)
happy downloading
The answer everyone's waiting for? (Score:2)
Well, do I win?
Low resolution... (Score:2)
From TFA: By zooming in on a massive cluster of galaxies, the movie highlights the morphology of the structure on different scales, and the large dynamic range of the simulation (10^5 per dimension in 3D).
Now I understand that this resolution means 10^15 voxels ((10^5)^3) but that only equates to a linear resolution of 1mm in a 10m wide universe. Impressive it may be, but it's a long way short of the real thing.
Dark Matter (Score:2)
In other words, they left out the entire observable universe. Not only does that simplify the calculations, it makes it a little difficult to truly authenticate the results. :)
dark matter is invisible (Score:2)
To simplify the computations, they considered only dark matter which composes most of the universe
no wonder those breathtaking images remain invisible...
Wallpaper (Score:2)
Re:Wallpaper (Score:2)
My God, it's full of stars! (Score:2)
Thought I'd beat someone to it.
Copyright? (Score:3, Interesting)
--grendel drago
Re: Shame (Score:2)
> Since it's pretty obvious that "dark matter" is just a hack to make the maths work; there's almost certainly no such thing.
Like the cosmological constant?
> Oh, well.
Let us know when your Nature article comes out.
At least TRY... (Score:3, Insightful)
I guess thats in the same class as "its KNOWN the earth is flat"...
So please give me a proof, or at least a good theory, why there cant be particles that dont interact with the strong or electromagnetic forces and have large mass?
We SEE the results of their gravitation (and not just with the galactic rotation, but you cannot really do cosmology ignoring them), so who are you to claim them a "hack to make maths work"?
(btw: maths work really most of the time. The trick is that the resu
Re:At least TRY... (Score:2)
The gavitational effects are more likely to have something to do with a hole in the gravitational theory; perhaps a sign of quantum effects in gravity/acceleration? Dark matter is just plain silly.
The other implication of dark matter theory that really points to it being wrong is that the age of distant galaxys is too great (in terms of stellar evolution and population mix)
Re:At least TRY... (Score:2)
I'm truly not trying to flame(bait) but there are so many people ready to take dark matter as a literal truth, but scoff at any notion of the supernatural.
And as for all those people only to willing to apply Occam's Razor to anything vaguely mystical - where are they now? What's more likely - incomplete knowledge of the long dist
Re:At least TRY... (Score:2)
I've always preferred to think that the equations of general relativity might be imperfect. After all, Newton's equations are simplifications of Einstein's, there's no reason why his might not be simplifications of <insert future clever basta
Re:At least TRY... (Score:2)
And if you first sentence represents what you think dark matter is and why you think it is postulated, you should take a MUCH closer look at cosmology.
Re:Shame (Score:3, Funny)
I'd have to disagree, because we've found several draft scientific documents in the Kiev that indicate that In Soviet Russia dark matter made the maths work.
Re:Shame (Score:2)
What are you sitting on then?
Re:Yes, but... (Score:2)
Re:Yes, but... (Score:2, Funny)
also, see the nice poste (Score:2)
sad mirrordot doesn't also take the links
Re:Breathtaking indeed. (Score:5, Insightful)
Re:Breathtaking indeed. (Score:2, Interesting)
The theories can tell you what happened a split nanosecond after the big bang and can track the expansion of the universe.
One of the basic principals all these theories hold common is that energy can never be created nor destroyed, only change form.
What I really want to know is what was the universe like a split nanosecond before the big bang.
Re:Breathtaking indeed. (Score:4, Informative)
There is no known way--and likely never will be--to know anything about existance outside of the post-big bang observable universe, other than indulging in wild and baseless speculation.
Re:Breathtaking indeed. (Score:3, Interesting)
Actually, this is not completely true. There are certain special conditions under which energy can be created, similar to the vacuum energy phenomenon. Furthermore, the big bang, specifically the first 10^(-43) seconds of the universe, is certainly another kind of special condition, the physics of which are n
Re:Breathtaking indeed. (Score:3, Funny)
We'll have a lot more to go on once we figure out how to point telescopes at right angles to reality.
Re:Breathtaking indeed. (Score:2)
Re:Breathtaking indeed. (Score:2, Insightful)
There's nothing arbitrary about it. Science is a description of how the world around us behaves; inventing fanciful and largely frivolous reasons t
Crazy talk (Score:2)
Oh.
Re:There is no bigbang or darkmatter (Score:2, Insightful)
"So the Deep Impact mission could prove to be an acid test. The electric theorists have made their position clear, and there won't be much wiggle room for the conventional "dirty snowball" hypothesis. If water is not observed to explode from the surface at the projectile's impact, a domino effect will be set loose. An absence of water would mean there is no mainstream model left, only the electric model would remain. A single event could thus alter the mindset of all who work