What is the differentce between science and pseudoscience?

Answer 1

One standard definition of science is that it makes claims that may be proven false. One excellent example of this is the concept of the luminiferous aether, which was the theoretical construct that scientists used in the 18th and 19th centuries to describe the transmission of light. They had a pretty elaborate theory on how it worked too, i.e. that the aether was a material of some sort, and that it operated like air transmitting sound waves. (Look up the Michaelson Morley experiment.)
Pseudoscience, in contrast, presents claims that either cannot be proven, cannot be disproved, or make grievous misuse of scientific concepts. My personal favorite whipping-boy here is homeopathy. Start by taking a substance which may or may not have certain curative powers. Dissolve said substance in water. Dilute said solution repeatedly. According to homeopathic practice (I shall not use the word "theory," because theories may be tested and proven or disproven), the water maintains a memory of the supposedly efficacious substance - and the more dilute the solution is, the greater its effectiveness.