The results of a study on a number of galaxies with a rich gaseous component are in agreement with what is expected from a theory proposed in the '80s, an alternative hypothesis of the existence of dark matter.
The results of a new study, which examined a sample of galaxies, are fully compatible with what is expected from a theory that could be called "vintage": a bit 'dated, not everyone likes it, but not thrown away. It is the MOND theory, Modified Newtonian Dynamics .
formulated and proposed in the early '80s, offers a modified Newtonian dynamics, or that set of physical laws that describe relationships between the forces and accelerations, including gravity.
There has always been perfect harmony between what is expected from the classical laws of Newton and the phenomena observed, at least until he decided to study the rotation of galaxies. It was then that we realized that the theory predicts something that does not really happen.
galaxies rotate on themselves differently from what is expected, as one moves away from the center the speed should decrease, and yet this does not occur. It is as if they were composed of a lot more matter than it is able to detect: they are not stars or gas, nothing known or visible in some way with our tools. At this point the roads are two. Or is this matter really is extra. Or the laws that we are not going well on a galactic scale.
If we choose the first path, here come into the scene dark matter: the theory that accepts that there is one that receives more support, the most fashionable, although the identity of this matter continues to be, precisely, obscure. However, if we assume that dark matter is not there and we know that laws should somehow change when you consider systems like galaxies, one of the proposed changes is precisely that the MOND theory has recently found new confirmation .
This study, conducted by Stacy McGaugh University of Maryland, examined 47 galaxies with a rich gaseous component and for all, found a compatibility very good between the observed data and theoretical predictions obtained by applying the laws of MOND.
were chosen particularly gas-rich galaxies because they contain relatively fewer stars and is the uncertainty in the estimation of the mass of stars to make the test inaccurate. It is essential to obtain reliable measurements of mass and rotation speed of galaxies in order to make reliable comparisons with the theoretical values \u200b\u200bMOND. Comparisons have been well demonstrated compatibility between observations and theory that goes beyond that obtained with the theoretical models that include dark matter.
If, however, adds up when it comes to galaxies, the MOND theory is not of great help by passing on scales even larger than those of galaxy clusters where the challenge is open to a more powerful rival, the dark energy. For the moment we must acknowledge that the MOND theory has worked: "if the correct theory is that dark matter," McGaugh asks, "why the world has proved its worth?". In any case, the theory of winning, whatever it is, must give an account of this fact also not negligible.
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