Who decided there would be 7 days in a week? Does every culture have 7 days per week?

Answer 1

Week (from Latin vicis,”change”), is the period of seven days now in universal use as a division of time. It is of Hebrew or Chaldean origin and is mentioned as a unit of time in the Bible (see Genesis 29:27). The division of the lunar month into seven-day periods probably began as a celebration of the creation of the world in six days with the seventh day for rest. The Roman week was an eight-day period until 303 ad, when official recognition of the Christian religion made it necessary to celebrate the Sabbath every seventh day. The English names for the days of the week—Sunday (Sol), Monday (Moon), Tuesday (Tui, the Saxon Mars), Wednesday (Woden, or Mercury), Thursday (Thor, or Jupiter), Friday (Frygga, or Venus), and Saturday (Saturn)—come from Roman or Norse names for the planets.

Answer 2

7 days of the week is based on the Biblical account of creation, where God made the earth in 6 days, resting on the seventh. This seventh day was called the Sabbath day, the day the Israelites were to rest and do no work. Sabbath is our Saturday--the 7th day of the week. The rest of the calendar has nothing to do with weeks, nor is there any intended correlation with the moon or sun. Any math you try to figure out on it is circumstance.

Only Judeo-Christian cultures originally had this setup, as you might imagine, but it was generally adopted by the rest of the world (for the most part) as the Gregorian calendar (which we use today) was brought during global colonization by Europeans.

Answer 3

I'd imagine it stems from the lunar cycle being 28 days and that being divided up into 4 phases of the moon...28 / 4 = 7.

Answer 4

try this site:
http://en.wikipedia.org/wiki/Maya_calendar