Well, the physical universe will still exist, but I don't think that
physics - the scientific study of said universe - will become sort of meaningless, I would think?
Why meaningless? Imperfect knowledge can still be useful, and ultimately that's the only kind we can ever have about anything.
"We could learn to sail the oceans and discover new lands and transport cargo cheaply... But in a few centuries we'll discover we were wrong and the Earth isn't really a sphere and tides are extra-complex so I guess there's no point."
Why meaningless? Imperfect knowledge can still be useful, and ultimately that's the only kind we can ever have about anything.
"We could learn to sail the oceans and discover new lands and transport cargo cheaply... But in a few centuries we'll discover we were wrong and the Earth isn't really a sphere and tides are extra-complex so I guess there's no point."