In astronomy or cosmology, what is Dark Matter?

Uniontera number 11-1, hope it helps.

Existence is the time expressed by light itself. http://www.youtube.com/watch?v=AN1jTwHUC7E

1. Arrow A is the laser work. (Same time work)

2. Arrow B is the reason of gravity. (also, Higgs boson individually / Different time work)

3. The rose line is the beginning light. (result from Bible)

4. The existence of different time. (result from relativity of light)

5. 2 dimension is not a space. (result from 2-axis, math)

6. Universe came from nothing. (result from No.5 / cf. Playing with bubbles)

6-1. A barrier[posititon] exist between the inner and outer bubbles. But universe do not have that barrier. (Cause of Inertia / Reason of Sun / Position of Antimatter / cf. Expansion)

6-2. Nothing is not a no existence. No existence is a zero dimension. There is two zero dimension. One has a position. The other doesn't have a position. These different positions were connected by something. That "something" is not a what but a way. (Cause of Light)

7. Progress / Event / Probability is a time. (This is my trinity.)

8. Wave-particle duality of light, creation & evolution, uncertainty principle, etc. (result from No.7)

9. Coalescing of different time. (Cause of Rotation & Spin / Equator has plenty of time.)

10. Your so-called black hole is a wholly condensed time. (cf. Kerr spacetime)

11. The reason of "your so-called magnetic field". (result from step3 and 4)

11-1. The reason of "your so-called dark matter". (result from step3 to 4 / Energy-Mass duality / cf. Dark energy "step4 to 3")

12. The reason of "your so-called electric field". (result from the crack of time / Same time's crack is a different time's coalescing. / Cause of Static electricity)

13. Your so-called "space" is a crack of time. (result from No.12 / Cause of Lightning)

14. Boundary is a crack of space. (result from No.13 / Same space's crack is a different time's contact. / Cause of Superfluid / cf. Fractal)

15. Boundary is nothing. Your so-called hole is a boundary itself. Also, nothing is K=0 temperature. (result from No.14 / cf. Calabi-Yau, Hilbert space)

16. This is a wall of your so-called fire. (result from No.15) - copyright ⓒ uniontera

Our nonsense has come from one time. Uniontera is a key.

English is not my first language, sorry!

If it is difficult to understand, just remember & enjoy "Hand touching everything is a time". This is the only one result of uniontera.

First, it is dark, meaning that it is not in the form of stars and planets that we see. Observations show that there is far too little visible matter in the Universe to make up the 25% required by the observations. Second, it is not in the form of dark clouds of normal matter, matter made up of particles called baryons. We know this because we would be able to detect baryonic clouds by their absorption of radiation passing through them. Third, dark matter is not antimatter, because we do not see the unique gamma rays that are produced when antimatter annihilates with matter. Finally, we can rule out large galaxy-sized black holes on the basis of how many gravitational lenses we see. High concentrations of matter bend light passing near them from objects further away, but we do not see enough lensing events to suggest that such objects to make up the required 25% dark matter contribution.

Dark matter is a theoretical construct used to explain

the discrepancy between the observed behaviour of the

universe and the predicted behaviour based on accepted

theories of gravitation. If the only matter in the universe was

that which we can see, the universe should behave much differently

than it does.

Nobody knows. Simple as that.

Matter that doesn't absorb or reflect light.