2C-C is a psychedelic drug of the 2C family. It was first synthesized by Alexander Shulgin, sometimes used as an entheogen. The full name of the chemical is 2,5-dimethoxy-4-chlorophenethylamine. In his book PiHKAL (Phenethylamines i Have Known And Loved), Shulgin lists the dosage range as 20–40 mg. 2C-C is usually taken orally, but may also be insufflated. 2C-C is unscheduled and uncontrolled in the United States, but possession and sales of 2C-C could potentially be prosecuted under the Federal Analog Act because of 2C-C's close structural similarity to 2C-B, though there are no known cases of this for 2C-C.

Not much information is known about the toxicity of 2C-C. Many users report that 2C-C is gentler and more sedating than other closely related psychedelic phenethylamines.^{[citation needed]}

Albert Einstein ( /ˈælbərt ˈaɪnstaɪn/; German: [ˈalbɐt ˈaɪnʃtaɪn] ( listen); 14 March 1879 – 18 April 1955) was a German theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics. While best known for his mass–energy equivalence formula E = mc² (which has been dubbed "the world's most famous equation"), he received the 1921 Nobel Prize in Physics "for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect". The latter was pivotal in establishing quantum theory within physics.

Near the beginning of his career, Einstein thought that Newtonian mechanics was no longer enough to reconcile the laws of classical mechanics with the laws of the electromagnetic field. This led to the development of his special theory of relativity. He realized, however, that the principle of relativity could also be extended to gravitational fields, and with his subsequent theory of gravitation in 1916, he published a paper on the general theory of relativity. He continued to deal with problems of statistical mechanics and quantum theory, which led to his explanations of particle theory and the motion of molecules. He also investigated the thermal properties of light which laid the foundation of the photon theory of light. In 1917, Einstein applied the general theory of relativity to model the structure of the universe as a whole.