1. Welcome to Religious Forums, a friendly forum to discuss all religions in a friendly surrounding.

    Your voice is missing! You will need to register to get access to the following site features:
    • Reply to discussions and create your own threads.
    • Our modern chat room. No add-ons or extensions required, just login and start chatting!
    • Access to private conversations with other members.

    We hope to see you as a part of our community soon!

Featured Serious Dark Matter Problems

Discussion in 'Science and Religion' started by Native, Apr 11, 2021.

  1. Native

    Native Free Natural Philosopher & Comparative Mythologist

    Joined:
    Aug 25, 2011
    Messages:
    4,003
    Ratings:
    +535
    Religion:
    Natural Perceptions
    Subject: 10 Problems with Dark Matter - With Pavel Kroupa

    Pavel Kroupa
    (born 24 September 1963 in Jindřichův Hradec, Czechoslovakia) is a Czech-Australian astrophysicist and professor at the University of Bonn.



    Luckely, some scientists have observed the flaws of "dark matter" and other invented dogmas.

    BTW: There is nothing new to me in his critical analysis and perceptions, but he also needs more alternate informations if solving some more problems.
     
    #1 Native, Apr 11, 2021
    Last edited: Apr 11, 2021
  2. Regiomontanus

    Regiomontanus retired astronomer

    Joined:
    May 24, 2017
    Messages:
    1,923
    Ratings:
    +1,847
    Religion:
    Eastern Orthodox
    The video is almost an hour long. How about the main takeaways?
     
    • Like Like x 2
    • Optimistic Optimistic x 2
    • Useful Useful x 1
  3. epronovost

    epronovost Well-Known Member

    Joined:
    Oct 15, 2019
    Messages:
    3,528
    Ratings:
    +3,459
    Religion:
    Atheist/non-religious
    Here is a good resumé of his argument. To be fair, it's a good one, but it shifts a weakness compared to the more standard model.

    In 1997 and in Heidelberg Kroupa, together with Ulrich Bastian, took the first precise measurement of the spatial movement of two extragalactic systems. In 1997 he also discovered stellar-dynamic solutions for the satellite galaxies of the Milky Way without the need for exotic dark matter. His work implies a possible connection of the satellite galaxies with the Bulge of the Milky Way. This connection can be explained by a collision of the early Milky Way with another young galaxy during which the satellite galaxies formed as tidal dwarf galaxies about 11 Gyr ago. This is shown in a series of research papers with Manuel Metz and Marcel Pawlowski.
     
    • Informative Informative x 6
  4. Pete in Panama

    Pete in Panama Active Member

    Joined:
    Mar 31, 2019
    Messages:
    341
    Ratings:
    +144
    Religion:
    Baha'i
    Given the guy's assumptions it's not to hard to defend what he's saying w/ logic, tho it's a lot easier to defend "Last Thursdayism " w/ logic.
     
  5. Regiomontanus

    Regiomontanus retired astronomer

    Joined:
    May 24, 2017
    Messages:
    1,923
    Ratings:
    +1,847
    Religion:
    Eastern Orthodox
    Thanks. There have been some cases over the years which can be modeled without the need for dark matter. MOND is the best known approach but there have been others (I don't recall this case). But anyway, much (!) more has been done on this since the 90s obviously and of course we have examples now that cannot be explained by MOND. If these folks have come up with something that holds up to scrutiny, great! But that does not seem to be the case. The example with our Local Group members is not relevant to dark matter; no mysteries there.
     
    • Informative Informative x 1
  6. Native

    Native Free Natural Philosopher & Comparative Mythologist

    Joined:
    Aug 25, 2011
    Messages:
    4,003
    Ratings:
    +535
    Religion:
    Natural Perceptions
    Thanks for your resumé.

    If "dark matter" is on it´s way out, scientists need to come up with another explanation of the observed galactic rotation curve, which contradicts Newton´s "Universal Law of Celestial Motions".

    And what then about the assumed 28 % dark matter in the Universe?

    Regarding the Milky Way orbiting dwarf galaxies, I don´t think the hypothesized "collisions of galaxies" is correct. If something is orbiting a center, the dwarf galaxies shall be connected to the very formation of the Milky Way mother galaxy.

    The same really goes for the formation of the Solar System, which also orbits the Milky Way center - but then we operate with two different types of orbital motions in the same overall system which has to be explained by alternate ideas of formation.

    I´m not surprised that MOND have it´s problem even when having adjusted "gravity". Pavel Kroupa also mean that even Einstein´s relative gravity has to be revised and adjusted.

    - In many attempts to find a TOE, "gravity" is "the bad boy in the class", and I don´t think a TOE can be made before scientists revisit and take up the galactic rotation curve issue once more and include other fundamental forces but "gravity" (The issue which led to the assumption of "dark matter" in the first place).
     
  7. night912

    night912 Well-Known Member

    Joined:
    Mar 26, 2019
    Messages:
    1,886
    Ratings:
    +769
    Religion:
    Not religious
    Leave the science work for the scientists.
     
    • Winner Winner x 7
    • Optimistic Optimistic x 1
  8. Native

    Native Free Natural Philosopher & Comparative Mythologist

    Joined:
    Aug 25, 2011
    Messages:
    4,003
    Ratings:
    +535
    Religion:
    Natural Perceptions
    Not at all. Convensus scientists have had their "dark matter" chances for about 100 years now without solving anything at all.

    They can´t solve old scientific problems by using old scientific dogmas. Alternate thoughts are needed.
     
  9. Twilight Hue

    Twilight Hue Twilight, not bright nor dark, good nor bad.

    Joined:
    Mar 7, 2009
    Messages:
    38,401
    Ratings:
    +16,466
    Religion:
    Philosophical Buddhism
    Yea. Some cliff notes for dummies would be nice.
     
  10. Native

    Native Free Natural Philosopher & Comparative Mythologist

    Joined:
    Aug 25, 2011
    Messages:
    4,003
    Ratings:
    +535
    Religion:
    Natural Perceptions
    These are already provided by @epronovost above here at #3.
     
    #10 Native, Apr 12, 2021
    Last edited: Apr 12, 2021
  11. Twilight Hue

    Twilight Hue Twilight, not bright nor dark, good nor bad.

    Joined:
    Mar 7, 2009
    Messages:
    38,401
    Ratings:
    +16,466
    Religion:
    Philosophical Buddhism
    I'd rather have factual science and not alternatives on matters like this. Unless of course the alternate uses science and can get published in journals like Nature and Scientific American for people to read.
     
  12. Native

    Native Free Natural Philosopher & Comparative Mythologist

    Joined:
    Aug 25, 2011
    Messages:
    4,003
    Ratings:
    +535
    Religion:
    Natural Perceptions
    Well, you have all that in Pavel Kroupa´s video here at
    #1 - and all his critiques of the standard thinking too as well.
     
  13. Regiomontanus

    Regiomontanus retired astronomer

    Joined:
    May 24, 2017
    Messages:
    1,923
    Ratings:
    +1,847
    Religion:
    Eastern Orthodox
    I watched the first ~20 minutes and might watch more later. He is not a crank. But one thing that jumped out at me was his assumption about all galaxies have dark matter halos. So when talking about the Small and Large Magellanic Clouds he assumes each has a significant halo and how the three of them should be the source of significant Chandrasekhar friction but none is observed so therefore there are no dark matter halos in nature. The problem, though, is that we know his assumption is not a universally valid one. Take this recent case (there are others):


    "But astronomers have been puzzled since last year's discovery of 'NGC1052-DF4', a stable and long-lived galaxy with almost no dark matter. How can the galaxy exist without this important ingredient? Are our theories about galaxy formation wrong?

    Today, an international study led by UNSW Sydney suggests the dark matter was there to begin with—it's just been stolen by a greedy neighbour.

    "The dark matter isn't there because it's already been removed," says Dr. Mireia Montes, lead author of the study and astronomical researcher at UNSW Science and the Space Telescope Science Institute.

    "We found that the gravitational pull from the nearby massive galaxy NGC1035 is removing its stars—and dark matter."

    The research, published today in The Astrophysical Journal, provides an explanation for why so much dark matter is missing from the galaxy without contradicting our existing understanding of galaxy formation.

    "When two galaxies are passing close to each other, they suffer from each other's gravitational pull," says Dr. Montes. "Our very deep imaging found faint stars being pulled away by the larger galaxy—an interaction called 'tidal disruption'." "

    https://phys.org/news/2020-11-case-dark-galactic-mystery.html
     
    • Informative Informative x 2
  14. Native

    Native Free Natural Philosopher & Comparative Mythologist

    Joined:
    Aug 25, 2011
    Messages:
    4,003
    Ratings:
    +535
    Religion:
    Natural Perceptions
    IMO, this is the main problem of asserting something unobserved "stuff" when a scientific problem has occured - as in the case of the discovery of the galactic rotation curve discrepancy.

    This invented "dark stuff" apparently does´n fit in some cases - which IMO, then should be completely discarded as an scientific universal solution.
    This is of course very convenient being able just to add and to subtract this or that when this is needed, but it leaves it all to be very inconsistent and untrustworthy.

    In fact, it wery well could be that the (§) understanding of galaxy formation is wrong as it needs "dark matter" to work in the scientific calculations in the first place.
     
    #14 Native, Apr 12, 2021
    Last edited: Apr 12, 2021
  15. Regiomontanus

    Regiomontanus retired astronomer

    Joined:
    May 24, 2017
    Messages:
    1,923
    Ratings:
    +1,847
    Religion:
    Eastern Orthodox
    I have no dog in this fight. There is much we do not know about galaxy formation and we are indeed pretty clueless about dark matter and energy. I was a skeptic of both for a long time (though it had little impact on my research) but the case is very strong now, overall. But who knows.
     
  16. We Never Know

    We Never Know Well-Known Member

    Joined:
    Jan 20, 2019
    Messages:
    7,469
    Ratings:
    +4,979
    Religion:
    It exists
    I like you have no dog in this fight.
    However dark matter was said to be slowing the expansion of the universe until 5bya when dark energy started rapidly expanding it. I wonder several things such a ..
    1. Did dark energy just appear 5bya?
    2. If it was always there why wasn't it speeding expansion before 5bya?
    3. Did dark energy become more abuntant than dark matter 5bya and reverse the effects of dark matter?
    4. Over time did the dark matter become weaker and dark energy become stronger?

    Who knows
     
  17. Polymath257

    Polymath257 Think & Care
    Staff Member Premium Member

    Joined:
    Mar 28, 2017
    Messages:
    21,504
    Ratings:
    +26,058
    Religion:
    Non-theist
    1. No.
    2. Radiation, and then matter, dominated the energy balance. Over time, though, the expansion diluted their effects.
    3. It's more that dark matter (and ordinary matter and radiation) diluted under the expansion but dark energy did not.
    4. Dark energy did not become stronger (as far as we know). But because of expansion, matter and energy contribute less to the overall energy balance.
     
    • Informative Informative x 1
  18. Polymath257

    Polymath257 Think & Care
    Staff Member Premium Member

    Joined:
    Mar 28, 2017
    Messages:
    21,504
    Ratings:
    +26,058
    Religion:
    Non-theist
    One option: use the full version of general relativity:

    https://arxiv.org/pdf/1508.07491.pdf

    Interestingly enough, it seems to fit the observed rotation curves without problems.

    Whether it also deals with lensing and the Bullet cluster has yet to be calculated.
     
  19. We Never Know

    We Never Know Well-Known Member

    Joined:
    Jan 20, 2019
    Messages:
    7,469
    Ratings:
    +4,979
    Religion:
    It exists
    Is the following statement true that there is 2.5x more mass of dark energy than dark matter? If so has it always been that way since neither can be created or destroyed?

    "Dark energy is the far more dominant force of the two, accounting for roughly 68 percent of the universe’s total mass and energy. Dark matter makes up 27 percent. And the rest — a measly 5 percent — is all the regular matter we see and interact with every day."

    What’s the Difference Between Dark Matter and Dark Energy?
     
  20. Polymath257

    Polymath257 Think & Care
    Staff Member Premium Member

    Joined:
    Mar 28, 2017
    Messages:
    21,504
    Ratings:
    +26,058
    Religion:
    Non-theist
    Energy conservation is tricky in general relativity since curvature effects have to be taken into account.

    The easy answer is no, there is NOT a constant ratio between the different components of the total energy.

    For example, ordinary matter has a density that decreases as the cube of the scale factor. In essence, this means that the same energy is distributed over a larger volume and the volume goes as the cube of the scale factor.

    But for radiation (light), the energy density decreases faster than that: it decreases as the fourth power. The reason is that the wavelength of the light is stretched as the volume is increasing. But a larger wavelength corresponds to a smaller energy.

    Dark energy is just strange: it's density stays the same under expansion. In a sense, we can think of it as an energy density of empty space. So the more space, the more dark energy contributes to the total.

    Running things backwards, in the very early universe the energy from radiation was dominant. But, with expansion, the energy of the radiation falls faster than that for matter, so eventually matter dominated the energy balance. The energy from dark energy was there, but smaller. But, as the expansion continued, both the energy density for radiation and that for matter fell more. Eventually, they fall under the *constant* density from dark energy.

    In this scenario, dark matter acts the same as ordinary matter: it's density decreases as the volume.
     
    • Like Like x 1
    • Informative Informative x 1
Loading...