the planets they visit, which are structures that would go beyond the material strength that ice could support. 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." Theoretical physicist Michio Kaku praised the film for its scientific accuracy and has said Interstellar "could set the gold standard for science fiction movies for years to come." Similarly, 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." Wormholes and black holes To create the visual effects for the wormhole and a rotating, supermassive black hole (possessing an ergosphere, as opposed to a non-rotating black hole), Thorne collaborated with Franklin and a team of 30 people at Double Negative, providing pages of deeply sourced theoretical equations to the engineers, who then wrote new CGI rendering software based on these equations to create accurate simulations of the gravitational lensing caused by these phenomena. Some individual frames took up to 100 hours to render, totaling 800 terabytes of data. Thorne described the accretion disk of the black hole as "anemic and at low temperature—about the temperature of the surface of the sun," allowing it to emit appreciable light, but not enough gamma radiation and X-rays to threaten nearby astronauts and planets. The resulting visual effects provided Thorne with new insight into the gravitational lensing and accretion disks surrounding black holes, resulting in the publication of three scientific papers. Christopher Nolan was initially concerned that a scientifically accurate depiction of a black hole would not be visually comprehensible to an audience, and would require the effects team to unrealistically alter its appearance. The visual representation of the black hole in the film does not account for the Doppler effect which, when added by the visual effects team, resulted in an asymmetrically lit black and blue-black hole, the purpose of which Nolan thought the audience would not understand. As a result,