noun
Big Bang
Refers to the cosmological theory of the universe's origin from a primordial explosion.
宇宙大爆発は約138億年前に起こったと考えられている。
The Big Bang is thought to have occurred about 13.8 billion years ago.
ビッグバン is the more common katakana loanword for the Big Bang theory. 宇宙大爆発 is a native Japanese term used in scientific or explanatory contexts.
Compound of 宇宙 (uchū, 'universe') + 大 (dai, 'big') + 爆発 (bakuhatsu, 'explosion'), literally 'great explosion of the universe'. A calque of the English 'Big Bang'.