Since the consequence, spacetime, is "doomed", the undelying premise, Einstein's 1905 constant-speed-of-light postulate, is false. The combination "wrong consequence, true premise" is forbidden by logic:
http://www.thebatt.com/science-techn...3aa345281.html
"Spacetime is any mathematical model used in physics to explain physical phenomenas of the universe by combining space and time in one continuum. [....] Arkani-Hamed said."Because of the existence of gravity and quantum mechanics, we believe that the concept of spacetime is doomed and there are many simple thought experiments that tell us that space time is doomed."
http://www.cctv-america.com/2016/08/...ntury-geniuses
"Nima Arkani-Hamed is considered one of the top minds at the forefront of theoretical physics, and a 21st century genius. Known for being a disruptive force in science over the course of his career, his revolutionary theories about the functioning of the universe openly push boundaries."
http://community.bowdoin.edu/news/20...rs-of-gravity/
"Special relativity is based on the observation that the speed of light is always the same, independently of who measures it, or how fast the source of the light is moving with respect to the observer. Einstein demonstrated that as an immediate consequence, space and time can no longer be independent, but should rather be considered a new joint entity called "spacetime."
Pentcho Valev