Giant Sheets Of Dark Matter Detected 231
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."
What if.... (Score:1, Interesting)
Three times larger? (Score:4, Interesting)
The Rubber sheet analogy is WRONG!!! (Score:5, Interesting)
Current analogy of space time:
Take a rubber sheet and stretch it out over a frame and drop a bowling ball and marble and drop them on it, they push down and those dents are gravitation fields in space-time.
New more correct analogy:
Take a swimming pool and fill it all the way to the top with water. THEN, stretch a rubber sheet over it and seal it so that no water leaks out. Then put your bolwing ball and marble on it. Draw a line running between the bowling ball and marble, and take that cross section, note that the bowling ball and marble behave the same way at close distance like they do above, but when they are a opposite sides of the pool there is a slight "repulsive" effect. We call that Dark Energy! This repulsive effect also can help stick objects together applying a "pressure" against all the other objects, hence "Dark Matter". This effect will also affect light waves moving past it, hence gravitational lensing.
I'll take my Nobel prize now!
Re:Three times larger? (Score:5, Interesting)
Re:Sheets and Filaments (Score:4, Interesting)
However, galaxies also form 'sheets and filaments' at extremely large scales, as well; presumably, should these folks figure out how to find smaller structures, they should look somewhat more familiar.
Re:The Rubber sheet analogy is WRONG!!! (Score:3, Interesting)
If you took all the matter in the universe and spread it out evenly, it would put the same "pressure" against space time, like a uniform sheet or membrane, make a large enough disturbance and all that matter will start flowing to one area and the sheet will stretch till it hit the bottom of the pool and rebounds, hence the Big Bang.
Re:Sheets and Filaments (Score:3, Interesting)
If I were feeling particularly sci-fi, I'd probably call it something like 'gravitational bleed-over from close neighboring dimensions'.
Re:Three times larger? (Score:4, Interesting)
Gravity, it is wrong (Score:5, Interesting)
These are the reasons I work on a rank 1 field theory for gravity. For the details, read as much of this thread as you like: http://physicsforums.com/showthread.php?t=87097 [physicsforums.com] This is a LONG thread, more than 36k views, I make learn things along the way. Right now I am trying to find derive the Maxwell equations, and then the unified field theory, instead of using tensors. Quite a bit of fun. I have never had to write so many partial differential equations in my life.
Doug
Simulation error (Score:5, Interesting)
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.
So they didn't really detect dark matter then (Score:4, Interesting)
So from what I gather, this is still more pie in the sky from dark matter proponents then? It has been argued that we don't need dark matter to explain the universe, and that a minor tweaking of Newton's law of universal gravitation would explain everything. As of yet, no one has truly detected/demonstrated dark matter particles.
If our fundamental laws are a bit off, then this bending/distorting of the light would be explained by that, and these dark matter constructions would be nothing but an illusion created by a mathematical error in our first principles. Therefore, until someone can actually demonstrate a dark matter particle, I am not jumping on this bandwagon. There are experiments underway to actually find dark matter, and for now I await their results.
Re:Simulation error (Score:3, Interesting)
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.
If your hypothesis is correct then we wouldn't know the answer to this because we are not the ones running the simulation & whoever is obviously has technology & knowledge greater than our own hence, it would be possible to compute gravity directly in every known situation. This would also fit the rules of quantum physics in that you can either know the state or position of things but not both since the simulator would be using this OR clause to save memory and/or processing capability.