May 10, 2024 05:26 PM
https://theconversation.com/is-dark-matt...sts-228826
EXCERPTS: . . . This brings us to the Cassini mission, which orbited Saturn between 2004 and its final fiery crash into the planet in 2017. Saturn orbits the Sun at 10 AU. Due to a quirk of Mond, the gravity from the rest of our galaxy should cause Saturn’s orbit to deviate from the Newtonian expectation in a subtle way.
[....] But Cassini did not find any anomaly of the kind expected in Mond. Newton still works well for Saturn.
One of us, Harry Desmond, recently published a study investigating the results in greater depth. Perhaps Mond would fit the Cassini data if we tweaked how we calculate galaxy masses from their brightness? That would affect how much of a boost to gravity Mond has to provide to fit models of galaxy rotation, and thus what we should expect for Saturn’s orbit.
Another uncertainty is the gravity from surrounding galaxies, which has a minor effect. But the study showed that, given how Mond would have to work to fit with models for galaxy rotation, it cannot also fit the Cassini radio tracking results – no matter how we tweak the calculations.
[...] That’s not the only bad news for Mond. Another test is provided by wide binary stars – two stars that orbit a shared centre several thousand AU apart. Mond predicted that such stars should orbit around each other 20% faster than expected with Newton’s laws. But one of us, Indranil Banik, recently led a very detailed study that rules out this prediction...
[...] Results from yet another team show that Mond also fails to explain small bodies in the distant outer Solar System...
[...] The standard dark matter model of cosmology isn’t perfect, however. There are things it struggles to explain...
[...] Ultimately though, Mond, as presently formulated, cannot be considered a viable alternative to dark matter any more. We may not like it, but the dark side still holds sway... (MORE - missing details)
EXCERPTS: . . . This brings us to the Cassini mission, which orbited Saturn between 2004 and its final fiery crash into the planet in 2017. Saturn orbits the Sun at 10 AU. Due to a quirk of Mond, the gravity from the rest of our galaxy should cause Saturn’s orbit to deviate from the Newtonian expectation in a subtle way.
[....] But Cassini did not find any anomaly of the kind expected in Mond. Newton still works well for Saturn.
One of us, Harry Desmond, recently published a study investigating the results in greater depth. Perhaps Mond would fit the Cassini data if we tweaked how we calculate galaxy masses from their brightness? That would affect how much of a boost to gravity Mond has to provide to fit models of galaxy rotation, and thus what we should expect for Saturn’s orbit.
Another uncertainty is the gravity from surrounding galaxies, which has a minor effect. But the study showed that, given how Mond would have to work to fit with models for galaxy rotation, it cannot also fit the Cassini radio tracking results – no matter how we tweak the calculations.
[...] That’s not the only bad news for Mond. Another test is provided by wide binary stars – two stars that orbit a shared centre several thousand AU apart. Mond predicted that such stars should orbit around each other 20% faster than expected with Newton’s laws. But one of us, Indranil Banik, recently led a very detailed study that rules out this prediction...
[...] Results from yet another team show that Mond also fails to explain small bodies in the distant outer Solar System...
[...] The standard dark matter model of cosmology isn’t perfect, however. There are things it struggles to explain...
[...] Ultimately though, Mond, as presently formulated, cannot be considered a viable alternative to dark matter any more. We may not like it, but the dark side still holds sway... (MORE - missing details)
