- In modern physics, the double-slit experiment demonstrates that light and matter can satisfy the seemingly incongruous classical definitions for both waves and particles. This ambiguity is considered evidence for the fundamentally probabilistic nature of quantum mechanics. This type of experiment was first performed by Thomas Young in 1801, as a demonstration of the wave behavior of visible light. In 1927, Davisson and Germer and, independently George Paget Thomson and his research student Alexander Reid demonstrated that electrons show the same behavior, which was later extended to atoms and molecules. Thomas Young’s experiment with light was part of classical physics long before the development of quantum mechanics and the concept of wave–particle duality. He believed it demonstrated that Christiaan Huygens’ wave theory of light was correct, and his experiment is sometimes referred to as Young’s experiment or Young’s slits.
- Mount Rushmore (summitpost.org)
The Mount Rushmore climbing area is only the 2nd SummitPost.org “climbing” submission for South Dakota. This is not overly surprising due to the state’s remoteness but is astonishing regarding the quality of granite routes that can be found here. There are two popular climbing areas south of Rapid City, South Dakota in the Black Hills National Forest (1.2 million acres!): the Needles area, which is known for its ethics via trad climbing and limited fixed protection; and the Mount Rushmore climbs which feature many fully bolted sport routes.