3 ms·

It all depends on what you mean by "view". In my understanding it does not immediately follow that it must be "viewed" by making use of collision experiments.

It all depends on what you mean by "view". In my understanding it does not immediately follow that it must be "viewed" by making use of collision experiments. This picture in my opinion "views" dark matter just as much as you would "view" neutrinos: https://upload.wikimedia.org/wikipedia/commons/thumb/a/a8/1e0657_scale.jpg/1200px-1e0657_scale.jpg https://upload.wikimedia.org/wikipedia/commons/thumb/a/a8/1e... (the bullet cluster) Regardless, I find the discussion on the meaning of ill-defined laymen language tiring while we probably agree on the actual facts.

adrian_b 3y ago
No, the current status of neutrinos and of dark matter are not at all comparable. Like another poster has already written, the status of dark matter is like that of the neutrinos when their existence had been postulated, but before means to detect them by alternative methods have been devised. In the beginning, the existence of neutrinos has been presumed because in certain reactions the conservation of the energy and of the linear momentum and of the angular momentum was not observed. So every time when there were missing energies and momenta, it was assumed that they had been carried away by neutrinos. In the same way, nowadays whenever there is an extra gravitational force, it is assumed that there exists some dark matter that is the source of the extra force. Until another means of determining the existence of dark matter is discovered, this does not constrain enough the properties of the dark matter. For any mathematical model of the gravitational forces, when we see that it does not match reality we can add a fictitious distribution of dark matter computed to match the observations. In fact, for the postulated neutrinos even before their first detection we had much more knowledge about them, because they had to satisfy many distinct conservation laws, so we knew that they must be fermions with null electric charge and h_bar/2 spin and that their mass must be much smaller than the mass of the electron. On the other hand, we are really in the dark about dark matter. We know nothing about any properties of any constituents of dark matter.

adrian_b 3y ago

No, the current status of neutrinos and of dark matter are not at all comparable. Like another poster has already written, the status of dark matter is like that of the neutrinos when their existence had been postulated, but before means to detect them by alternative methods have been devised. In the beginning, the existence of neutrinos has been presumed because in certain reactions the conservation of the energy and of the linear momentum and of the angular momentum was not observed. So every time when there were missing energies and momenta, it was assumed that they had been carried away by neutrinos. In the same way, nowadays whenever there is an extra gravitational force, it is assumed that there exists some dark matter that is the source of the extra force. Until another means of determining the existence of dark matter is discovered, this does not constrain enough the properties of the dark matter. For any mathematical model of the gravitational forces, when we see that it does not match reality we can add a fictitious distribution of dark matter computed to match the observations. In fact, for the postulated neutrinos even before their first detection we had much more knowledge about them, because they had to satisfy many distinct conservation laws, so we knew that they must be fermions with null electric charge and h_bar/2 spin and that their mass must be much smaller than the mass of the electron. On the other hand, we are really in the dark about dark matter. We know nothing about any properties of any constituents of dark matter.