Is our universe haunted? It might look that way on this dark matter map. The gravity of unseen dark matter is the leading explanation for why galaxies rotate so fast, why galaxies orbit clusters so fast, why gravitational lenses so strongly deflect light, and why visible matter is distributed as it is both in the local universe and on the cosmic microwave background. The featured image from the American Museum of Natural History‘s Hayden Planetarium previous Space Show Dark Universe highlights one example of how pervasive dark matter might haunt our universe. In this frame from a detailed computer simulation, complex filaments of dark matter, shown in black, are strewn about the universe like spider webs, while the relatively rare clumps of familiar baryonic matter are colored orange. These simulations are good statistical matches to astronomical observations. In what is perhaps a scarier turn of events, dark matter — although quite strange and in an unknown form — is no longer thought to be the strangest source of gravity in the universe. That honor now falls to dark energy, a more uniform source of repulsive gravity that seems to now dominate the expansion of the entire universe.
Source: https://apod.nasa.gov/apod/astropix.html
Illustration Credit & Copyright: Tom Abel & Ralf Kaehler (KIPAC, SLAC), AMNH
Scents of Science 
October 25, 2020 at 5:50 pm
on one hand: despite its simple approximation as a force, and its beautifully subtle description as a property of spacetime, we’ve come to realize over the past century that we still don’t know what gravity actually is. on the other hand: Black holes are only a tentative explanation to make OUR calculations work for the 5% we can see.
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October 25, 2020 at 5:52 pm
we don’t really know what black holes are, neither what gravity is…
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