# １１　Dark Matter and Dark Energy【Exploring the universe】Dialogue with the Universe

１１　Dark Matter and Dark Energy【Exploring the universe】Dialogue with the Universe

○Dark Matter
・ Dark matter is matter and energy, which is supposed to describe the structure of the universe and the operation of the galaxy. (Fritz Zwicky in 1934) [1]
・ It is named darkness from the fact that is not only not emitting light but also not reflecting.
・Dark matter is distributed spherically around the galaxy.
・From it is to us that can not be only three spatial dimensions recognition, dark matter can not be seen in motion in the other seven spatial dimension to us. [2]
・Mass of dark matter is a kinetic energy of the particles(Elementary particle?　In superstring theory, it is string that vibrates at a high frequency) in motion in the other seven spatial dimensions. [2]
• It can be detected by the gravitational lens effect.

○Dark Energy
・In observation of galaxies and galaxy clusters(Cosmic structure) that have been made in the 1990s, if the space has to be flat, only dark matter was suggested that not be explained only about 25% of the universe mass. If the dark energy compensate about 70% of the remaining, can be explained that the universe is flat.
・The universe(space-time) is expanding at an accelerated pace. The dark matter and substances act as a brake against the expansion of the universe in order to attract each other by gravity. On the other hand, dark energy acts as a repulsive force. ・・・？
・And the universe (space-time) even though continued accelerated expansion, the density of dark energy does not become thin.
・The identity of the dark energy is not known. [3] (Related to the quantum theory of gravity ...？)

☆ There are important things that do not appear in the table.

【Reference】
1. Why dark matter is assumed?
１） By the third law of Kepler, from the orbital period and the semi-major axis of the two stars we can obtain the sum of the mass of the stars.
Ｍ＝ａ＾3／ｐ＾2
Ｍ：Sum of the mass of stars（solar mass）
ｐ：Orbital period（year）
ａ：Semi-major axis of two stars（astronomical unit: au
２）When estimating the total mass of galaxies, based on the movement of the galaxy its periphery, the result is a few hundred times the mass which is estimated based on the total luminance of galaxies and the number of galaxies observed optically.
３）Therefore, it is assumed that there are substances that are not visible.
2. 「宇宙は何でできているのか」村山　斉(Japanese)
3. Dark Energy, Dark Matter - NASA Science - Science@NASA