evidence: The theory of "chemtrails" has been around for several decades; online essays connecting commercial aircraft to chemical spraying and weather modification appeared in the late 1990s. According to chemtrails believers, the government or another shadowy force is using commercial aircraft to release chemicals into the atmosphere — for anything from weather modification to mass mind control. [...] In the last few years, however, experts say the claim has changed. Some now say that chemtrails are being used to carry out solar geoengineering — and that researchers and government employees investigating solar geoengineering are part of the larger scheme. [...] The Tennessee bill, sponsored by state Sen. Steve Southerland (R) and state Rep. Monty Fritts (R), says that "it is documented" that the federal government or other entities "may conduct geoengineering experiments by intentionally dispersing chemicals into the atmosphere." The bill prohibits the release of chemicals "with the express purpose of affecting temperature, weather, or the intensity of sunlight." The bill has not passed the Tennessee House.