Job said God suspends the earth over nothing. And God confirmed that Job had spoken the truth about him. So if God is right that Job is right about this, the earth does not have anything under it supporting it. The Bible disagrees, though.

Job previously suggested that the earth is on pillars, and since he was talking about God at the time, that must have been true too. Asaph says God agrees that the earth has pillars. Samuel’s mother says God has set the earth on foundations. David and Solomon agree that the earth has foundations, and David also says the earth is floating on the sea. Other psalmists, like Asaph, agree that the earth is on foundations.

So does Isaiah, and most of the time when he says that, he’s claiming to be reporting what God says about the foundations of the earth. Jeremiah says God says the earth has foundations below it, Zechariah says the earth has a foundation, and Micah says God says it will always have foundations. God even directly states in the book of Job that the earth has a foundation.