It’s my understanding that flat earthers also believe that the earth is a number under 15 thousand years old. I believe that the earth is a couple billion years old, and the universe is over a dozen billion years old. There are lots of things telling us that the earth and universe are very old, including various earth terrain, fossils, carbon dating, observing very distant space objects and other phenomena, etc.
I understand that not all (even not many) flat earthers believe space objects are real, despite the interesting things one can observe with telescopes and basic equipment. I’m curious if a FEr would confirm that FET in general believes the earth is relatively young, provide supporting arguments, and refute the example arguments that a) the Grand Canyon took millions of years to carve and b) observable phenomena like redshift and objects in space are as they seem. I pulled these out of a metaphorical hat, and there’s plenty more examples that could be discussed that indicate the earths very old age.
I think if we could establish that earth is very old, a cascade of determinations would occur leading to being required to accept modern day physics, as FET partially rejects.