Astrophysicists have long speculated that ordinary matter made up only a fraction of the total mass in the universe, with the rest accounted for by mysterious, unobserved “dark matter”. Recent research might indicate they were wrong and the missing matter is ordinary baryonic matter after all.
A more readable, less technical article:
Actually, no. The observations refer to the missing baryonic matter that is expected to be there, but hasn’t been observed yet. NOT the dark matter component:
This “missing matter” doesn’t refer to dark matter, the mysterious stuff that remains effectively invisible because it doesn’t interact with light (sadly, that remains an ongoing puzzle). Instead, it is “ordinary matter” made up of atoms, composed of electrons, protons, and neutrons (collectively called baryons) which make up stars, planets, moons, and our bodies.
(from the space.com reference)
I suspect that further observations and research will find that all of the remaining missing matter consists of baryonic matter and other particles that make up the standard model. Either that, or corrections to the theory of gravitation that obviate the need for dark matter.
IMO, if dark matter existed, it would have been detected by now. I may be wrong, of course, but I suspect dark matter will go the way of the luminiferous ether that was once speculated to fill all of space.
That would imply that we are seriously under counting the mass in most galaxies, but getting it right in others! Since there are galaxies that seem to not contain dark matter (there are galaxies where the observed gravitational attraction matches what we would expect from what can be seen, and just forgetting about dark matter). The idea is that during the collisions of two galaxies with dark matter: the regular matter can separate from the dark matter, leading to galaxies without dark matter. This should be possible since dark matter is presumably much different than regular matter (that it doesn’t interact electrically: you can’t hit it with a photon). This could easily cause dark and regular matter components (that started with the same positions and trajectory) to have different trajectories, causing the visible components of the galaxy to go one way, and the dark matter components to go another direction (leading to us occasionally finding a galaxy that seems to be missing its dark matter).
There’s a lot of physics that has no real explanation and some of it makes no sense as to why it’s that way. For example, why are there three generations of leptons rather then just one? Or why does matter-antimatter asymmetry exist? Perhaps there’s an underlying explanation that we haven’t discovered yet for these and other things we don’t understand yet.
Science is littered with “theories” that didn’t pan out, like the luminiferous ether and phlogiston. Fortunately, one of the things that separates science from religion is that science discards theories that evidence shows aren’t correct.
I have an idea about dark matter . . . which seems so obvious that I can’t believe that it hasn’t occurred to someone else at some point, yet I haven’t found a mention of it anywhere.
There is an equivalence between mass and energy, as energy can be converted into mass and vice-versa.
The Universe is expanding outward from itself because of the Big Bang, and this constant outward expansion represents a tremendous amount of kinetic energy.
If this kinetic energy was–somehow–converted into mass, would this be enough mass to represent the invisible dark matter?
Isaac Asimov wrote a brilliant essay that seems relevant to my point. He mentioned that scientists were misled into believing that there was a small planet between Mercury and the Sun because Mercury’s and Venus’ motions suggested a gravitational perturbation.
Later, this astronomical discrepancy was resolved when Einstein’s famous equation (often printed on tee shirts and applied out of context by people who want to seem educated) demonstrated that the potential energy represented by the Sun’s gravitational field also created its own gravity.
Isaac Asimov communicated the details of how an understanding of General and Special Relativity could account for Mercury’s perturbations, and this hypothetical intra-Mercurial planet was no longer needed.
When I re-read this essay after considering dark matter, I wonder if the kinetic energy of the expanding Universe causes the astronomic discrepancies that we attribute to dark matter?
The essay was called “The Planet that Wasn’t,” which was published in a book of the same name by Issac Asimov in 1975.
This essay is available for free from the Internet Archive online library if you wish to see the context of this idea for yourselves.
Presumably, what you are suggesting would be the source of energy for the creation of all matter (dark matter and regular matter).
My favorite hypothesis for the origin of energy/matter that caused the big bang is a quantum fluctuation.
I may not have communicated well.
My point is to wonder if the kinetic energy of the expanding Universe creates its own gravity like the potential energy of the Sun.
If the potential energy of the Sun’s gravitational field also creates its own gravity, then what of the kinetic energy of the expanding Universe?
After all, the gravity of the potential energy of the Sun’s gravity is significant enough to perturb Mercury’s orbit, then what of the gravity represented by the kinetic energy of the expanding Universe?
Can this be what makes us think that dark matter exists?
There’s a hypothesis that the total amount of energy in the universe is zero, that the energy bound up in matter plus the energy in photons, etc., is exactly balanced out by the negative energy associated with gravity.
If this is the case, then why does the Universe expand? Or seem to expand?
What drives the dark matter discussion is the observation that most galaxies don’t seem to have anywhere near the amount of mass required to generate the gravity required to maintain their shape (not fly apart). Leading to two obvious explanations:
Well this will make some people’s heads explode. I’m thinking in particular of a panentheist and prolific poster on another site who is convinced that dark matter means that science is ignorant about most of reality.
I provided an explanation for the emergence of the dark matter concept in this post, while dealing with an ignorant mythology fanboy.
As I stated in that post, the following two postulates are not particularly remarkable:
[1] the postulate that there exists missing mass - since we already have evidence in abundance for particles with mass, adding some more is parsimonious with respect to additional assumptions. It also has the benefit of being supported by simulations of galaxy rotation curves.
[2] The postulate that the missing mass consists of particles that do not interact via the electromagnetic force - again, we already have evidence for one of these, in the form of the neutrino. Postulating that other such particles exist isn’t that great a leap into the unknown as a result.
Since the particles in question possess mass, they are required to interact via gravity by definition, and their presence should therefore be detectable via appropriate gravitational effects, such as gravitational lensing. An example of mapping dark matter halos via this process, is provided here (we can safely assume that the journal Science isn’t a crackpot publication).
Any alternative to the dark matter hypothesis has to provide an explanation for data such as the aforementioned example. Without which, any alternative is dead in the water.
Oops. Didn’t see this. Just started a topic on it myself. Pretty huge discovery so I don’t know whether to delete it. Used a different source. This news is surprisingly getting little attention at this point. If it gets support from other researchers then it will likely swamp the net. With so few scientifically literate reporters around nowadays I shouldn’t be surprised really.