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posted by Fnord666 on Thursday August 20 2020, @10:52PM   Printer-friendly
from the get-one-while-it's-hot dept.

The Universe Has Made Almost All the Stars It Will Ever Make:

But there's a big puzzle here. Exactly what puts a cap on the number of stars the universe has made and will ever make? This question has long been a subject of intense astrophysical debate, particularly in relation to the stellar composition of individual galaxies. For example, our current cosmological paradigm (or at least the one that most scientists subscribe to) is that we live in a universe dominated by dark matter, and in a dark matter universe the biggest galaxies should have formed the most recently,4 being assembled by the hierarchical, gravitationally driven merger of smaller systems. Yet if you examine very large, massive galaxies you find that they tend to be composed of older stars, suggesting that they've already sat around in their dotage for a very long time.

To try to explain this, astronomers invoke the idea of "quenching," where something acts to suppress or shut down the formation of new stars across galaxies. Not surprisingly, you need a pretty potent mechanism to quench anything on these scales, and among the most plausible culprits are the supermassive black holes that exist at the core of most galaxies and which can flood the space around them with photons and particles emitted from material as it screeches toward their event horizons. That outward transfer of energy can, quite literally, blow away the interstellar gas that would otherwise cool and clump into new stars.

The precise details of how this might work are certainly not yet fully understood. But there are new tantalizing clues in the fact that the masses of supermassive black holes appear to correlate with the mass of stars contained in their host galaxies.5 That is pretty shocking because even a supermassive black hole a billion times the mass of our sun only occupies a volume similar to that of our solar system. So somehow a galaxy that spans tens of thousands of light-years is intimately related to what is, in effect, a microscopic dot at its center.


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  • (Score: 0, Insightful) by Anonymous Coward on Thursday August 20 2020, @11:37PM (5 children)

    by Anonymous Coward on Thursday August 20 2020, @11:37PM (#1039598)

    Who gives a shit anymore? Dark matter is the most obvious wrong idea in science history so anything that assumes dark matter, like this article, is also wrong.

    How many hundreds of billions have been spent on looking for evidence of dark matter and there is none? GR makes the wrong predictions, and has since the 1930s. That is all this is.

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  • (Score: 2, Informative) by khallow on Friday August 21 2020, @01:18AM (1 child)

    by khallow (3766) Subscriber Badge on Friday August 21 2020, @01:18AM (#1039649) Journal

    How many hundreds of billions have been spent on looking for evidence of dark matter and there is none?

    Neutrinos are an obvious counterexample. We've found dark matter with the right sort of characteristics. We just haven't found enough.

    We may never find enough dark matter, because it isn't there in the necessary quantity, but it's a far cry from finding none at all.

    • (Score: 1) by fustakrakich on Friday August 21 2020, @05:24AM

      by fustakrakich (6150) on Friday August 21 2020, @05:24AM (#1039779) Journal

      :-) When you travel at or near the speed of light, all that "dark" matter will light up! Bigger than Times Square!

      It's a Doppler thing

      --
      La politica e i criminali sono la stessa cosa..
  • (Score: 2) by maxwell demon on Friday August 21 2020, @01:03PM (2 children)

    by maxwell demon (1608) on Friday August 21 2020, @01:03PM (#1039853) Journal

    Dark matter is the most obvious wrong idea in science history so anything that assumes dark matter, like this article, is also wrong.

    Yeah sure, and all astrophysicists are stupid, and you (probably without any astronomy knowledge beyond popular science articles) can have a better understanding than those people who dedicated their whole lives to studying it.

    Of course it may turn out that dark matter is the wrong hypothesis. But if so, your agreement with the facts will only be coincidental.

    Actually, while I don't really care one way or another, I do hope that one day dark matter will be proven beyond any doubt just because otherwise all those morons who “knew” that dark matter was wrong without actually having any knowledge beyond some popular science articles they've read will boast themselves with “I told you so”.

    Actually I'm convinced that the majority of them would be strong proponents of dark matter if scientists had come to the conclusion that it is a bad model, and favoured another option instead.

    GR makes the wrong predictions, and has since the 1930s. That is all this is.

    Well, you couldn't have illustrated your lack of knowledge better. Here's a hint: Why do you think the most prominent alternative to dark matter is called “Modified Newtonian Dynamics” and not “Modified Einsteinian Dynamics”?

    --
    The Tao of math: The numbers you can count are not the real numbers.
    • (Score: 0) by Anonymous Coward on Sunday August 23 2020, @04:46AM (1 child)

      by Anonymous Coward on Sunday August 23 2020, @04:46AM (#1040673)

      "Yeah sure, and all astrophysicists are stupid, and you (probably without any astronomy knowledge beyond popular science articles) can have a better understanding than those people who dedicated their whole lives to studying it."

      While I'm not taking any positions on this (TBH, I don't really know enough about this to take any positions) I generally see appeals to authority as a sign of weakness. Arguments like "you think you know better than the professionals" is not an argument.

      If someone has a specific argument to make one way or another then make it. Claims like "they know better because they studied it longer and therefore you lose" is not an argument but a sign of weakness.

      • (Score: 2) by maxwell demon on Sunday August 23 2020, @03:08PM

        by maxwell demon (1608) on Sunday August 23 2020, @03:08PM (#1040808) Journal

        You're misunderstanding the concept of “appeal to authority.”

        If I had claimed that dark matter is true because the majority of astrophysicists think so, then that would be an appeal to authority.

        But that's not what I did. The post I answered to basically claimed that the author knows better than those astrophysicists, and moreover that one has to be pretty stupid to believe what those astrophysicists believe, without giving any evidence that this claim is backed up by any knowledge at all (and indeed, some evidence that there is a distinct lack of knowledge). That is, the poster has not just made a claim about physics (dark matter is wrong) but about the astrophysicists (they have to be pretty stupid to believe that). And that claim I countered, and for that it is not an appeal to authority, because there is lots of evidence for them being knowledgeable and not entirely stupid. That doesn't mean they are always right, but it means their position isn't completely unreasonable.

        And yes, “you think you know better than the professionals” is an argument if the one this is aimed to shows no evidence of actually knowing better.

        --
        The Tao of math: The numbers you can count are not the real numbers.