# ９　The size of the Universe【What is the Universe？】Dialogue with the Universe

９　The size of the Universe【What is the Universe？】Dialogue with the Universe

・The size of the universe is more than 93 billion light-years(ly). [1]　　　　　　　　　　　　　　　　　　　　　　　 ・・・0.92×１０ˆ１１
Surface that the universe is expanding at the speed of light[2]
・・・0.36×１０ˆ１１
・Distance to the Andromeda Galaxy(the nearest galaxy) is about 2.5 million ly 　　　　 ・・・2.5×１０ˆ６
・By the way, the disk of the Milky Way galaxy is about 100 000 ly in diameter.　　　　　　　　　　　　　　　　　　　　　　　　　　 ・・・１×１０ˆ５
・Distance to the nearest star　　　　　　　　　　　　　　　　・・・４×１０ˆ０
・Solar system is about 100,000 ly in diameter.　 　 ・・・0.6×１０ˆ−３
・Distance to the Sun from the Earth　　　　　　　　　　　 ・・・1.6×１０ˆ−５
・Diameter of the sun　 　　　　　　　　　　　 ・・・1.5×１０ˆ−７
・The Earth is about 13,000 km in diameter.　 ・・・1.4×１０ˆ−１２
・Human height is about 1.7m. 　　　　　　　　　　　　　・・・1.8×１０ˆ−１６
(The length of the DNA in the cell of the human is 1.8 m.)
・The size of human cells is about 15μm.　　　　　　　　　・・・1.6×１０ˆ−２１
・The size of the atom　　　　 　　　　　　　　　　　　　 ・・・1×１０ˆ−２６
・The sizeof hadron (proton, neutron) ・・・1×１０ˆ−３１
☆The size of the atom and the nucleus is different enough human height and cell. So, the nucleus is not visible even look at the atom.
・The length of "String" and "other seven spatial dimensions" contemplated in the superstring theory　　　　　　　　　　　　　　　　　　　　・・・1×１０ˆ−５１

☆If the reference unit of the size of the universe is the speed of light, the size of the parallel universe is about １×１０ˆ５１ly.
☆It may be there are the 82nd power piece of 10 universe in the parallel universe.

[Expansion of the universe] [3]
• Since the Big Bang, The universe has continued to expand.
・Everything is moving away from us, with a speed that is proportional to its distance. ：The Hubble Law [4]
・ For expansion of the universe is the expansion of space-time itself, so it is also possible to exceed the speed of light.
・The universe is the same everywhere.：Uniformity
・Currently, the observable universe is expanding at 3.5 times the speed of light.
・Expansion of the universe is described in the general theory of relativity.
・ Outside of the observable universe is not known whether infinite or finite.

⇒ Therefore, in order to escape from our universe, rather than fly, it is necessary to exceed the time and space.

【Reference】
1. Wikipedia: 観測可能な宇宙(The universe/Japanese)
2. The galaxies, 18 billion light-years more distant from the observer, go far off beyond the speed of light. So we can not observe them.
3. Wikipedia:宇宙(The universe/Japanese)
4. edX/Cosmology/Section1 Space and Time/Lesson1/Referende Notes 1