Anon Archived A galaxy 11.3 billion light-years away appears filled with dark matter (sciencenews.org)
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Archived on: 11/16/2018 10:00:00 AM
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Anon Archived A galaxy 11.3 billion light-years away appears filled with dark matter (sciencenews.org)
submitted ago by 2677691?
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[–] ShinyVoater 2 points -1 points 1 point (+1|-2) ago
Standard orbital systems see objects further out have longer orbital periods further in. Galaxies, however, don't show this behavior and instead see a mostly constant rate of rotation throughout the system. You can write off dark matter as just a bookkeeping kludge to make mass appear where it has to be to make this absurdity work, but every other theory proposed so far has tripped over some experimental observation or another.
[–] B3bomber 1 point -1 points 0 points (+0|-1) ago
I'd love to see that proven considering the size of our galaxy, and where our solar system approximately is in it, has an orbital period of some odd 26,000 years (and I'd bet money there is no way in hell that is accurate). This means every other galaxy we look at follows that model too. We for absolutely fucking certainty do not have anywhere close to an observation time long enough to determine how long an orbit is of anything in those galaxies unless we are optically resolving the stars closest to the center inside the big glowing spiny ball of glowing dust several billion light years away.
[–] Commie_Meta ago
The stars' speed can be measured using the Doppler shift of their color spectra.
The European Space Agency's Gaia observatory will soon have complete speed observations of 1% of our galaxy's stars. It will be able to directly see the orbital effects of dark matter if there are any.
[–] ShinyVoater 1 point 0 points 1 point (+1|-1) ago
You don't have to see something make a complete orbit to know its period. For example, the distance from the center of a perfectly circular orbit can be determined by its distance from the center; increasing an object's speed simply serves to send it into a higher orbit with a longer period.
Galaxies are fairly well-rounded and should, by simple extrapolation, play by the same rules. Instead, the disc moves at a far more unified pace(like a CD), which requires mass to be where it visibly isn't. Some form of invisible matter is the only thing that makes sense with our current understanding of the universe. Alternate theories exist, of course, but, as I've said, they all have one problem or another that brings them out of agreement with observational evidence.