There’s something fundamental we all need to understand about dark matter—it may not actually be matter at all. Neil deGrasse Tyson has a bone to pick with this misnomer that is distracting physicists and the public from the real discoveries to be made. Scientists know very little about “dark matter”, and in fact it can only be observed indirectly by its effect on other objects. Tyson has a few suggestions for its re-naming: how about “Fred”, he jokes, which is a name devoid of any implied meaning—suitable for our current level of knowledge. But if you want it to sound sexy and be accurate, then the way to go is dark gravity, according to Tyson. Why? Because when you add up everything in the universe—the stars, moons, gas clouds, black holes, everything—85% of gravity is unaccounted for. That is so-called “dark matter”. What makes it so interesting isn’t the wild-goose-chase question of whether or not it exists, but why it doesn’t interact with ordinary, known matter? On the way to explaining that dark matter “doesn’t give a rats ass about us,” Tyson explores ghost particles, the essence of objects, and why we haven’t found any dark matter planets. Tyson’s new book is Astrophysics for People in a Hurry.
1- Dark matter doesn’t emit or absorb light.
2 - Dark matter works only via gravity
3 - Dark matter is extremely cold
4 - Dark matter is extremely weak (the weakest stuff)
5 - Dark matter doesn’t carry electric charge
6 - Dark matter is passive / neutral stuff
7 - Dark matter consists of (unknown) elementary particles
8 - Dark matter is much more than ordinary matter
9 - Dark matter must have some interaction with ordinary matter
10 - Dark matter can have non-gravitational interactions
11 - Dark matter must have own sector of existence
Ordinary matter interacts through the electromagnetic,
weak and strong forces – helping the visual matter
of our world to form complex systems
Stars, rocks, oceans, plants and animals owe their
very existence to the unity of the non-gravitational
(EM, weak, strong) forces with ordinary matter.
Familiar picture can be thought of interaction
between antiparticles (antimatter) and dark matter
Antiparticles (as EM forces) 10^36 times stronger
than weak particles of dark matter and therefore
can involve it in a process of ‘‘quantum gravity’’,
the earliest state of creation our material World.
Scientists still search a real / potential candidate for dark matter
Another alternative: ‘‘dark matter’’ is basis of classic ‘‘matter’’
Dark matter is a form of matter that is thought to account
for approximately 85% of the matter in the universe and
about a quarter of its total energy density.
New Hubble data suggests there is an ingredient missing from current dark matter theories
Date: September 10, 2020
Source: ESA/Hubble Information Centre
Summary: Recent observations have found that something may be missing from the theories of how dark matter behaves. This missing ingredient may explain why researchers have uncovered an unexpected discrepancy between observations of the dark matter concentrations in a sample of massive galaxy clusters and theoretical computer simulations of how dark matter should be distributed in clusters.
Journal Reference:
Massimo Meneghetti, Guido Davoli, Pietro Bergamini, Piero Rosati, Priyamvada Natarajan, Carlo Giocoli, Gabriel B. Caminha, R. Benton Metcalf, Elena Rasia, Stefano Borgani, Francesco Calura, Claudio Grillo, Amata Mercurio, Eros Vanzella. An excess of small-scale gravitational lenses observed in galaxy clusters. Science, 2020 DOI: 10.1126/science.aax5164