In 1973, Albert A. Jackson and Michael P. Ryan, physicists at the University of Texas, proposed that the Tunguska event was caused by a small (around 1017 kg to 1019 kg) black hole passing through the Earth. This hypothesis is considered flawed, as there was no so-called exit event, a second explosion occurring as the black hole, having tunnelled through the Earth, shot out the other side on its way back into space. Based on the direction of impact, the exit event would have occurred in the North Atlantic, closer than the impact event to the seismic recording stations that collected much of the evidence of the event. The hypothesis also fails to account for evidence that cosmic material was deposited by the extraterrestrial body, including dust trails in the atmosphere and the distribution of high-nickel magnetic spherules around the impact area.
In 1941, Lincoln LaPaz, and later in 1965, Clyde Cowan, Chandra R. Atluri, and Willard F. Libby suggested that the Tunguska event was caused by the annihilation of a chunk of antimatter falling from space. Antimatter is the extension of the concept of the antiparticle to matter, where antimatter is composed of antiparticles in the same way that normal matter is composed of particles. As with the above hypothesis described, this does not account for the mineral debris left in the area of the explosion.
The Wardenclyffe Tower: