Astronomers have found an enormous "void" in space 1.8 billion light-years across, the largest structure yet found in the universe. The void is aligned with a "cold spot" discovered in the cosmic microwave background. The void was found using the PAN-STARRS telescope on Maui and NASA's Wide Field Infrared Survey Explorer (WISE) in space. Detection of a supervoid aligned with the cold spot of the cosmic microwave background The study suggests that the void is draining light energy from the surrounding space, causing the cold spot. This supervoid may not be empty, but could be the lair of an ultra-massive black hole. Old theories of the universe can't explain a structure this large. The void could have been formed by an ultra-massive black hole emptying the space around it. The black hole would be primordial, born of a quantum fluctuation shortly after the Big Bang. Size of a black hole is limited by a "horizon distance" related to the speed of light. This immense void is one more sign that the speed of light was once much larger.