I can't help but notice you didn't ask it what's the world record for walking across the English Channel.
As already discussed, it's a sensible question and the straightforward answer is '11 hours' by an asylum seeker who was prosecuted for it. He walked, across, the English channel, in a certain time. So, the question has an answer, just like if there was a giant bridge over it and he'd walked across that instead of using a tunnel under it. (The biking record, if you were curious about other dry foot-powered modes, is apparently 55 minutes, and was legal. I didn't come across any further modalities like horseback or pogo stick, but given modern athletics, I d...
The big question about GPT-3 is not whether it can reproduce everything it's ever read, but whether it gleaned some understanding of the world while reading. Answering the question about the Channel with something like "No one ever walked across the Channel since humans can't walk on water" would indicate that it did, even though it'd be factually wrong.