The astrobiologist David Grinspoon criticized the dire "blight" situation on Earth portrayed in the early scenes, pointing out that even with a voracious blight it would have taken millions of years to reduce the atmosphere's oxygen content. He also notes that gravity should have pulled down the ice clouds. Neil deGrasse Tyson, an astrophysicist, explored the science behind the ending of Interstellar, concluding that it is theoretically possible to interact with the past, and that "we don't really know what's in a black hole, so take it and run with it". The theoretical physicist Michio Kaku praised the film for its scientific accuracy and said Interstellar "could set the gold standard for science fiction movies for years to come". Timothy Reyes, a former NASA software engineer, said "Thorne's and Nolan's accounting of black holes and wormholes and the use of gravity is excellent".