One thousand Chaturyugi cycles make one day of
Brahma. Also the same number of cycles represent one night of Brahma. The expansion, or creation of the universe is a day of Brahma and the contraction of the universe, dissolution, or
sleepiness of Brahma is called night or Pralaya. The universe expands for billions of years and then condenses. Afterwards, the universe expands again to make way for another creation or
Srishti and this cycle continues indefinitely.
In 1929, Edwin Hubble proved this Vedic formula to be accurate. Albert Einstein was even skeptical, but Hubble proved him to be incorrect. Of course, this information was stated in the Vedas much before the birth of Hubble.