In a recent press release from Fermilab, a recent survey of dark matter was announced. This survey was performed by the Dark Energy Survey using the Dark Energy Camera. To be clear, the main purpose of the Survey and the Camera is to observe and document dark energy, which makes up close to 70% of the observable universe and is "causing" the universe's accelerating expansion, but the nature of this specific survey was of dark matter, which is close to 25% of the observable universe and is responsible for the much larger amount of gravity present in galaxies than would be there if only due to conventional matter. The Camera for the Survey is extremely sensitive and looks at millions of galaxies to document their accelerated expansion over time, but the resolution is good enough to look at their specific structures, and so the dark matter forms within them as well.
Dark matter itself is mysterious and difficult to detect, since it interacts with other matter only weakly through gravity and doesn't obstruct or reflect light; however, its gravitational effects can be detected through gravitational lensing, an effect predicted by Einstein's General Relativity. This allows not only for the total amount of dark matter to be detected by subtracting the gravity of conventional matter from the gravity seen, but it also allows for the general shape of the dark matter formation to be detected.
As it turns out in this case, the shapes of dark matter formations match the predictions made based on where galaxies had formed. Normal matter was found to cluster around where the dark matter was clustered, and space between galaxies and there clusters were found to be relatively empty of both. At first, I questioned why the assumption being gone with was that conventional matter clustered around where the dark matter already was instead of other possibilities, but then I remembered that dark matter was present in the early universe and formed structures before conventional matter did. This makes it reasonable to abduce that dark matter formations attracted conventional matter, especially since the combined gravity of dark matter is so much greater and we have no reason to think that conventional matter produced it.
Although unnecessary, this review is also a nice additional confirmation of dark matter. Dark matter has been confirmed many times already, such as the Bullet Cluster analysis in 2006, and a recenter review of similar collisions; however, this is yet another level of confirmation through the analysis matching conventional theories. One would also not expect conventional matter to follow gravitational strands with models like MOND (modified Newtonian dynamics), but rather for the conventional matter and gravity to match perfectly, since the gravity is being produced by the conventional matter in the first place.
This is only the beginning of the analysis that the Dark Energy Survey will perform, and I am excited to see how the rest of it goes. The ultimate, and lofty goal of the endeavor is to document dark energy and (hopefully) determine its role and/or cause. Dark matter and especially dark energy are two of the most exciting cosmological mysteries we are confronted with today, and I would positively love to learn more about them!
As it turns out in this case, the shapes of dark matter formations match the predictions made based on where galaxies had formed. Normal matter was found to cluster around where the dark matter was clustered, and space between galaxies and there clusters were found to be relatively empty of both. At first, I questioned why the assumption being gone with was that conventional matter clustered around where the dark matter already was instead of other possibilities, but then I remembered that dark matter was present in the early universe and formed structures before conventional matter did. This makes it reasonable to abduce that dark matter formations attracted conventional matter, especially since the combined gravity of dark matter is so much greater and we have no reason to think that conventional matter produced it.
Although unnecessary, this review is also a nice additional confirmation of dark matter. Dark matter has been confirmed many times already, such as the Bullet Cluster analysis in 2006, and a recenter review of similar collisions; however, this is yet another level of confirmation through the analysis matching conventional theories. One would also not expect conventional matter to follow gravitational strands with models like MOND (modified Newtonian dynamics), but rather for the conventional matter and gravity to match perfectly, since the gravity is being produced by the conventional matter in the first place.
This is only the beginning of the analysis that the Dark Energy Survey will perform, and I am excited to see how the rest of it goes. The ultimate, and lofty goal of the endeavor is to document dark energy and (hopefully) determine its role and/or cause. Dark matter and especially dark energy are two of the most exciting cosmological mysteries we are confronted with today, and I would positively love to learn more about them!
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