APOD: Illustris Simulation of the Universe (2014 May 12)

[APOD Robot]

Illustris Simulation of the Universe

Explanation: How did we get here? Click play, sit back, and watch. A new computer simulation of the evolution of the universe -- the largest and most sophisticated yet produced -- provides new insight into how galaxies formed and new perspectives into humanity's place in the universe. The Illustris project -- the largest of its type yet -- exhausted 20 million CPU hours following 12 billion resolution elements spanning a cube 35 million light years on a side as it evolved over 13 billion years. The simulation is the first to track matter into the formation of a wide variety of galaxy types. As the virtual universe evolves, some of the matter expanding with the universe soon gravitationally condenses to form filaments, galaxies, and clusters of galaxies. The above video takes the perspective of a virtual camera circling part of this changing universe, first showing the evolution of dark matter, then hydrogen gas coded by temperature (0:45), then heavy elements such as helium and carbon (1:30), and then back to dark matter (2:07). On the lower left the time since the Big Bang is listed, while on the lower right the type of matter being shown is listed. Explosions (0:50) depict galaxy-center supermassive black holes expelling bubbles of hot gas. Interesting discrepancies between Illustris and the real universe do exist and are being studied, including why the simulation produces an overabundance of old stars.

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[FLPhotoCatcher]

Cool simulation and music. I have to wonder how realistic it is though. Even before reading that there are discrepancies in the model vs reality regarding star types and abundances, I recalled that, a few days ago, there was an APOD that mentioned that in star clusters, "the youngest stars are concentrated near the middle of the cluster." That's the opposite of models that predict star formation to "begin first in the denser center and progressively move outward toward the edges leaving the older stars, not the younger ones, in the center."

[Nitpicker]

Cool simulation and music. I have to wonder how realistic it is though.

Wondering is good. There is still enough mystery in the Universe for everyone.

[neufer]

Absolutely beautiful simulation!
......................
Just wish someone, at the close of the simulation, would add zooming into where our local galaxies are, then the Milky Way, then the Sun, then the blue dot from Saturn and finally Home.

This aint us.

This is a simulation of how the sorts of wrinkles in the cosmic microwave background would most likely evolve into something like us over 13.8 billion years.

[Chris Peterson]

Cool simulation and music. I have to wonder how realistic it is though. Even before reading that there are discrepancies in the model vs reality regarding star types and abundances, I recalled that, a few days ago, there was an APOD that mentioned that in star clusters, "the youngest stars are concentrated near the middle of the cluster." That's the opposite of models that predict star formation to "begin first in the denser center and progressively move outward toward the edges leaving the older stars, not the younger ones, in the center."

A simulation is a type of experiment. The purpose of an experiment is to either disprove or to bolster a theory or hypothesis. Or increasingly, a model, which is a complex hybrid of interacting theories.

Because this simulation broadly matches what we actually observe, we should have confidence that it probably is substantially accurate. Because it differs from reality in details, we know it still has some errors or omissions. But that's the point. This gives theorists ideas about which areas of the current models need more development.

[Evenstar]

Cool simulation and music. I have to wonder how realistic it is though. Even before reading that there are discrepancies in the model vs reality regarding star types and abundances, I recalled that, a few days ago, there was an APOD that mentioned that in star clusters, "the youngest stars are concentrated near the middle of the cluster." That's the opposite of models that predict star formation to "begin first in the denser center and progressively move outward toward the edges leaving the older stars, not the younger ones, in the center."

A simulation is a type of experiment. The purpose of an experiment is to either disprove or to bolster a theory or hypothesis. Or increasingly, a model, which is a complex hybrid of interacting theories.

Because this simulation broadly matches what we actually observe, we should have confidence that it probably is substantially accurate. Because it differs from reality in details, we know it still has some errors or omissions. But that's the point. This gives theorists ideas about which areas of the current models need more development.

Then here's to the further development of this simulation!

[Chris Peterson]

Then here's to the further development of this simulation!

Of course. Science is the only method of developing knowledge we've ever devised that only moves forward. The quality of our physical knowledge only increases, because every test inspires new ones, every test slightly advances what we know to be true.

[Ron-Astro Pharmacist]

Then here's to the further development of this simulation!

Of course. Science is the only method of developing knowledge we've ever devised that only moves forward. The quality of our physical knowledge only increases, because every test inspires new ones, every test slightly advances what we know to be true.

I recently heard that the difference between physics and metaphysics was that science was essentially the study of scientifically provable or proven philosophical ideas. That being said metaphysical concepts are then left for those to devise new experiments that prove them worthy to create divisions of science. I wonder where that leaves simulations? As you say Chris – somewhere on the verge of developing new knowledge.

It seems to me it's possible that when we know how close this simulation is to reality may be about the same time we discover that our reality is a simulation as some hypothesize.

http://www.nature.com/news/simulations- ... am-1.14328


Not to be contrary but it's interesting the different avenues that simulations take. I wish I could fully appreciate the effort today's APOD took. Thanks to those who put it together!!

[Chris Peterson]

I recently heard that the difference between physics and metaphysics was that science was essentially the study of scientifically provable or proven philosophical ideas. That being said metaphysical concepts are then left for those to devise new experiments that prove them worthy to create divisions of science. I wonder where that leaves simulations? As you say Chris – somewhere on the verge of developing new knowledge.

This simulation is physics, pure and simple. No metaphysics to be seen here.

It seems to me it's possible that when we know how close this simulation is to reality may be about the same time we discover that our reality is a simulation as some hypothesize.

It doesn't matter to me if reality is a simulation. What matters to me is that we understand the rules.

[Boomer12k]

So.....if OLDER Stars in Globular Clusters of the Milky Way Galaxy, are 12 billion years old....and as a forming Galaxy around 10 billion years old....then we started back around 2 to 3 billion years in the time frame of THIS simulation....and yet....there is ONLY DARK MATTER FORMING, as given in the right side corner of the screen......giving the structure to the Universe....BUT THERE ARE STARS AT THAT TIME....So, there is Hydrogen, and NOT just Dark Matter at that time....as we SEE STARS then. And so you have Gas Temperature and Dark Matter Simultaneously, (so my observation is the simulation is not taking early hydrogen formation into account, it would seem to me)...and the actual matter is heavier as a Gas...so has more influence gravitationally, and thus the "Structure of the Universe".

There are articles on "The Oldest Stars In the Milky Way"...and such....some estimates are up to 14.5 billion years old.....

Recombination of Elements, the early forming of Hydrogen, is said to have taken place around 378,000 years after the Big Bang.....Thus....Stars and Galaxies can form MUCH EARLIER, and MORE SOLIDLY than this simulation would suggest....And as such....there would be LESS INFLUENCE BY DARK MATTER....as something HEAVIER has actually formed ALREADY, and is acting on Spacetime....THUS, not so much need for Dark Matter as an influence on the early formation of the Structure of the Universe....

Just my suppositions this afternoon....

:---[===] *

[southern cross]

Very impressive - those explosions were a surprise. Had a quick look at the Illustris website - there is lots more available there for those who have the time to explore. I will definitely be doing so. The video will be an excellent classroom activity with which to start a discussion.

[Chris Peterson]

So.....if OLDER Stars in Globular Clusters of the Milky Way Galaxy, are 12 billion years old....and as a forming Galaxy around 10 billion years old....then we started back around 2 to 3 billion years in the time frame of THIS simulation....and yet....there is ONLY DARK MATTER FORMING, as given in the right side corner of the screen......giving the structure to the Universe....BUT THERE ARE STARS AT THAT TIME....So, there is Hydrogen, and NOT just Dark Matter at that time....as we SEE STARS then. And so you have Gas Temperature and Dark Matter Simultaneously, (so my observation is the simulation is not taking early hydrogen formation into account, it would seem to me)...and the actual matter is heavier as a Gas...so has more influence gravitationally, and thus the "Structure of the Universe".

I think you are misunderstanding the simulation. Different things were simulated, but only subsets are displayed at any point.

All the dark matter in the Universe, and all the hydrogen in the Universe, were present within the first 20 minutes following the Big Bang. There are simply too many dimensions of data to display simultaneously when you only have color and intensity available. The simulation is certainly taking into account both dark matter and ordinary matter (including hydrogen) from the very beginning. I think the choice of what parameters to display at particular times was somewhat arbitrary, although it clearly makes sense to start with dark matter, since it was dominant in defining the structure of the Universe very early on.

Recombination of Elements, the early forming of Hydrogen, is said to have taken place around 378,000 years after the Big Bang

Hydrogen (in the form of free protons and deuterium) existed just minutes after the BB. Recombination defines the period when things cooled enough that electrons recombined with the hydrogen ions.

[tomatoherd]

All the dark matter in the Universe, and all the hydrogen in the Universe, were present within the first 20 minutes following the Big Bang.

How can any scientist talk about nanoseconds, seconds, one minute or even 20 minutes after the BB? If space itself was being formed, and an absolute "kilometer" then has no equivalence to a kilometer of today's Universe (i'm not phrasing this right,but you get my drift), then time was coming into existence too, and its flow and measure that early on cannot correlate with those #s today. And space seems even more concrete than time, which some have debated is an illusion of our consciousness.hu

[Chris Peterson]

How can any scientist talk about nanoseconds, seconds, one minute or even 20 minutes after the BB? If space itself was being formed, and an absolute "kilometer" then has no equivalence to a kilometer of today's Universe (i'm not phrasing this right,but you get my drift), then time was coming into existence too, and its flow and measure that early on cannot correlate with those #s today. And space seems even more concrete than time, which some have debated is an illusion of our consciousness.hu

All that exotic stuff like the creation of time and space itself happened in the first billionth of a second. After that, we actually have a pretty good handle on most of the physics, and the laws of nature as we observe them today seem to have been in place. So we can very reasonably talk about what was happening 20 minutes after the BB.

[Boomer12k]

Chris....

Thanks for your explanation. And it depends on where you read, I guess....

As I went to their website, I can see they actually did MORE...and combined things together, overlaying elements. But the depiction of today's APOD, gives a limited, and "straight line" IMPRESSION...

Dark Matter, and Dark Energy, are very much "Mechanisms behind the scenes", as UNSEEN and UNSUSPECTED for so long,...and thus as such are Metaphysical in Concept. Yes, there is some evidence for such a supposition, thus the science to figure out, What, How, and Why....but they are very much the "Ectoplasm" of the Universe, so to speak. A substance behind things, we don't directly observe, we see some effects, though..... The 11th Dimension is WHERE??? Exactly....all around us, (I presume), but we don't see it. Feel it, etc....But that is supposedly where all this Energy comes from...we just don't perceive it...

Do those Membranes still exist? Or did they dissipate in some sort of "Short"????

:---[===] *

[ta152h0]

I am going to grab me a drink and see if I can figure out where this is expanding to

[DavidLeodis]

It's a fascinating simulation of the Universe. Simulations of 'parallel universes' will be interesting, though I guess they may be the same!

On opening all of the very many links I did feel as exhausted as the child in the 'exhausted' link image. OK, I admit I very soon only had a cursory look at what was being brought up through the links.

PS. Assuming that the Universe does eventually start collapsing back I assume that time will still continue, but perhaps with increasing stranger effects as the Universe gets ever more compact!

[JohnD]

There is a loot of intense colour coding in that video. For instance the episode about halfway through which developes into a Hollywood car crash explosion and chain reaction. Peering into the screen I eventually saw that this was coded as "gas temperature", so some more guidance would be helpful to understanding. Was this a star forming epoch as successive gas clouds condensed and started their nuclear furnaces, leading to shock aves and more condensation, or what?

There are more detailed videos on the 'Net, some including simultaneous displays of differetanta spects of the moel. so a Master simulation must be available somewhere, preferably with controls so that the different colour codes can be chosen or even switched dutring the run.

Or do I ask too much for a simulation alleged to have used 20 million CPU hours?

John