Giant Sheets Of Dark Matter Detected

Wandering Wombat writes "The largest structures in the universe have been, if not directly found, then at least detected and pounced upon by scientists. 'The most colossal structures in the universe have been detected by astronomers who tuned into how the structures subtly bend galactic light. The newfound filaments and sheets of dark matter form gigantic features stretching across more than 270 million light-years of space — three times larger than any other known structure and 2,000 times the size of our own galaxy. Because the dark matter, by definition, is invisible to telescopes, the only way to detect it on such grand scales is by surveying huge numbers of distant galaxies and working out how their images, as seen from telescopes, are being weakly tweaked and distorted by any dark matter structures in intervening space.' By figuring how to spot the gigantic masses of dark matter, hopefully we can get a better understanding of it and find smaller and smaller structures."

Re:Heh

[KublaiKhan]

Interesting or noninteresting to -whom- exactly?

It's really probably just a point of view issue. After all, should there be 'dark matter organisms' of some kind, they'd be most likely supremely uninterested in the likes of us for anything other than curiosity value. However, we're rather interesting to us, being as we -are- us and we tend to be somewhat self-interested.

Sheets and Filaments

[TheEmptySet]

So we are to understand that dark matter, acted on only by gravity, forms sheets and filaments? We know very well what shapes distributions of particles form over time with only gravity acting on them and they look a lot like galaxies and very little like sheets and filaments. Can anyone clear this up for me?

Re:Three times larger?

[TheEmptySet]

It's a good philosophical question though. When is a collection of things (say atoms, bricks and mortar, etc.) a thing and when is it just lots of things? Deep down atoms don't come anywhere near touching each other to make molecules and larger structures. I myself am just a collection of tiny dots floating in space a long way from each other.

Re:How can they tell this is caused by Dark Matter

[Big_Breaker]

You are throwing up your hands WAY too soon and crying occam's razor.

Atmospheric distortions are not consistent over time or different locations and those distortions do not "lense" like gravity does. Also standard astronomic technique is to have someone confirm your results with a different telescope, in a different part of the world.

It may not be dark matter, but it's not a smudge on their mirror either.

Re:It May Be Dark...

[kalirion]

Could be just a bunch of black holes. Size to mass ration is pretty small, so you could easily miss them.

Re:Sheets and Filaments

[exp(pi*sqrt(163))]

Right. But it's important to show that theory and observation are in agreement here: both give you filaments.

Re:Simulation error

[teslar]

You joke, but consider if the universe were a simulation -- quantum mechanics makes a lot more sense in term of a simulation. Things like spooky action at a distance become lazy evaluation. Quanta become memory locations, variables. And so on. Quantum mechanics is easy to simulate. But how does one simulate gravity? It has to propagate in every direction at the something like speed of light or else -- god forbid -- information could travel faster than light. The whole concept of gravity, that every individual particle affects however slightly every other particle, is not possible to compute directly. Now suppose the universe were simulated as a sparse matrix. Each cell could contain a gravity component that stored the aggregate gravity force from each of a certain number of directions (perhaps expressed as several point masses). Depending on the number of directions this would give highly accurate simulation at a small scale, where error is absorbed as noise, while being computable for the overall universe as a whole. However the error would magnify over great distances due to 'floating point' type errors accumulating. What if what these people are seeing as dark matter is not matter at all, but simulation error. Perhaps even dark matter is related to a sparse simulation of the universe where intervening space is approximated by invisible masses that gravity affects but nothing else does. These mass would act to consolidate cells in the matrix to reduce the overall memory requirements.

That always gets me. People assume the universe is a simulation (unprovable in my opinion) and then proceed to explain a very small subset of physical phenomena in terms of computations they understand. Where does this idea that the Universe simulator would work anything like our computers come from? Consequently, how does the assumption that the Universe is a simulation help in any way given that it is unknown what computations give rise to it?

Another way to look at it: Every time a physicist describes a new effect with a formula, he has in fact given you a (mathematical) simulation of this effect. But that does not mean that this effect is a result from a simulation in the first place. And just because it is possible to think of a computational implementation that might behave similarly to an observed effect (which is a crude way of describing it mathematically if you can't do the maths) doesn't mean it is the result of a computational implementation in the first place. Assuming the Universe is a simulation does not add any insights, so why bother?

Also kinda reminded me of that old joke... An engineer thinks his equations are an approximation of reality but a Physiscist thinks reality is an approximation of his equations (meanwhile, the mathematician doesn't care....).

Re:Simulation error

[Anonymous Coward]

> "Aw, shucks... you guessed it! Now I have to stop the simulation and start over."

"There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable."

"There is another theory which states that this has already happened."

  - Douglas Adams, HHGTTG

Re:Simulation error

[SETIGuy]

Quantum mechanics is easy to simulate.

[yoda] Tried have you? [/yoda] If it's so easy, can simulate a single atom for me? Let's say a Beryllium atom of the most common isotope? Compute the exact energy levels of all of the electrons, and all of the electronic transitions. Now compare them to measured values and tell me again how simple it is to simulate quantum mechanics.