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A pair of researchers from the University of Nevada, Reno, in an attempt to detect and better define dark matter, have pulled off a pretty amazing science experiment. The team used 16 years worth of GPS data to turn the whole planet into a massive detector that might detect clumps of dark matter that could extend beyond the solar system.
Dark matter makes up roughly 85% of all matter in the universe, which is a real bummer for us humans — as we simply have no idea what it is, what it looks like, nothing. Astrophysics has provided multiple evidence that it actually exists, but so far, it’s always been beyond our grasp. As generally tends to happen when faced with great unknowns, we do however have quite a lot of hypotheses pertaining to its nature.
"So, the two gathered data from the 32 satellites that make up the 31,000-mile-wide GPS constellation and ground-based GPS stations, retrieving figures recorded every 30 seconds for the last 16 years. Data was retrieved from sources around the world, and in particular from NASA’s Jet Propulsion Laboratory. They then used a model to sift through this data, looking for irregularities in atomic clock signals.
[...] Aaaaaaand they didn’t find anything. It’s a bit disappointing, sure, but it’s not really surprising given how elusive dark matter has proven itself to be up to now. It has to be said, however, that while the team didn’t find any definitive proof to support their theory, it could be that the effect is simply more subtle than anything we can pick up, or that the Earth crosses lumps of dark matter very rarely."
https://www.zmescience.com/science/earth-dark-matter-sensor-gps/
(Score: 4, Informative) by Anonymous Coward on Sunday November 05 2017, @03:14PM (2 children)
physicist here. i don't work in cosmology or quantum field theory. I'm gonna summarize, for those actually interested in facts.
there are several ways to estimate how much matter there is in the universe.
you can count stars.
you can look at the microwave background, to see what conditions were like when the universe first became transparent.
and you can look at how general relativity predictions compare with actual measurements of star/galaxy/galaxy cluster movements.
as of right now, these different measurements contradict each other.
since we have very good verifications of general relativity (monumentally better since last year, and especially since a few weeks ago), we believe it to be true.
however, general relativity says that if galaxies behave in a certain way, then there must be more matter than we observe. in fact, it says space around these galaxies must be bent more than the directly observed matter could bend it.
therefore most physicists agree that there must be some sort of "matter", additionally to what we can observe because of EM radiation, that generates the required gravitational field modifications.
we call it "dark" because we don't know what it is, and it's quite literally dark.
theories conceptually distinct from general relativity can describe particles that only interact gravitationally with regular matter.
depending on some assumptions, predictions on how exactly they do interact can be made, and then experimentalists can verify whether or not these predictions are verified.
so:
1. dark matter "exists", as long as we don't have a better theory of gravity than general relativity.
in other words: if you believe in general relativity, and you believe cosmologists about various measurements, you automatically believe that dark matter exists (in the sense of mathematical logic).
2. various theoretical candidates for dark matter have been ruled out. the only conclusion is: it's weirder than we thought.
(Score: 2) by FatPhil on Monday November 06 2017, @10:54AM (1 child)
What's happened recently?
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2) by FatPhil on Monday November 06 2017, @11:07AM
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves