Six days is obviously a metaphor.. If "someone" could create a world in six days, why not six minutes, or six seconds. or six whateverons.. Manipulating matter is a hardly studied "science".. We have oh! so much to learn..
If God in the future gave you the power to do that (manipulate matter)..
What would YOU do with it(that GIFT).?.
Obviously? I don't think so. God himself stated while giving the Ten Commandments -- you know the ones that contain the commandment not to bear false witness -- that He created the heavens and the earth and all that in them is in "six days." He intended to convey the idea that it was the length of physical time equal to six literal spins of the earth on it's axis, as he then used that "fact" to justify keeping the seventh day (that's the 24 hour kind) as holy.
So the implication in Genesis 20 is that the days he was speaking of were the same length on the time line as the seventh day he now commanded the Israelites to rest on.
Is there anything else spoken by God in Exodus 20 that was "obviously" a metaphor?