There is much speculation, but the true answer is unknown. No one we know of has survived a trip to the edge and returned to tell the tale.

So, if I understand this correctly, the earth is either 4 billion years old or 7,000 years old, depending on who you ask, and in all that time, nobody has seen the edge of the earth? So, it is either an infinite plane, or that's pretty much impossible at this point in time. Who do you know that has set out to find the edge and never returned? Logic would have it, that, if the earth is indeed flat, there would be countless recorded attempts to find the edge, long before now. Even if they never returned, we would at least know who tried and failed...