Scientists Complete Universe Millennium Simulation

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."

Comments

Talk about bloat

[sygin]

"20 terabytes of data" This has to be the most bloated screensaver ever!

Re:Talk about bloat

[AndroidCat]

There's talk of Google buying them out and offering it as Google Everything.

Caveat -- cosmology not far from understood

[helioquake]

"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.

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

[Black Parrot]

> > "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.

evidence

[resistfascism]

Besides the argument that stars orbiting around the fringes of galaxies appear to be moving too fast to stay in orbit without extra mass, what other observable evidence of dark matter is there?

Re:evidence

[Use Psychology]

a good one is gravitational lensing by massive clusters -- a lens analysis of all the arcs seen in, for example, a cluster, can be used to infer the mass of the cluster, and hence see that it is inconsistent with the mass of all the luminous matter. i.e. dark matter

Re:evidence

[gilzreid]

Also, by measuring the expansion rate of the universe over a very long time (ie. billions of years), and making observations of the Cosmic Microwave Backgound (CMB, the left over radiation from around 300000 years after the Big Bang) we can calculate the amount of matter it must contain. Then from models of the Big Bang and the CMB observations we can also find the amount of 'normal' matter (ie atoms), which comes to about 4% of the so called 'critical density', which is the amount of matter/energy required to have the universe be spatially flat (expands forever but tends toward zero expansion rate as time goes to infinity)

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.

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Typical

[CleverNickedName]

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...

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

[syntaxglitch]

Bah.

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

[jfengel]

Actually, I think only a scientist would find that joke funny. A nonscientist is just going to give you dumb stares.

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.

Who is to say...

[seti]

That this whole universe as we see it is not an experiment in somebody's supercomputer?

So, to quickly simulate everything that exists...

[kahei]

...they left out everything that is actually known to exist.

Yay!

Re:Breathtaking indeed.

[Xaositecte]

"Just a theory" is a phrase that should never be used in the context of Scientific discussions. It shows a misunderstanding of what the word theory means in Science. A Theory, put simply, is an explaination for observed phenominon which can be experimentally disproven, and is capable of being used to make predictions. Mathmatical theory applies to the real world only insofar as it correctly explains real-world phenomina, and predicts the actions of the real universe. Current theories on the creation of the Universe are anything but simplistic, and are accurate according to the data we've collected so far. When more data comes along that proves the theory false or inadequate, the theory will have to change, creating a stronger theory. The idea that it's somehow worthless because it's incomplete is ridiculous.

Well, rumor has it that...

[alien-alien]

After 6 days of calculation, they took the next day off.