This is nothing like saying we will never fly a plane. Flight was always quite obviously possible, physically. Birds and other flying creatures did it all the t

This is nothing like saying we will never fly a plane. Flight was always quite obviously possible, physically. Birds and other flying creatures did it all the time. Gliders existed long before powered flight, so the basics of aerodynamics were understood well ahead of powered flight. Understanding time travel and its possibility is definitely purely based on the laws of physics. What else would it be based on?