A prototype jet engine can propel itself without using any fossil fuels, potentially paving the way for carbon-neutral air travel. The device compresses air and ionizes it with microwaves, generating plasma that thrusts it forward, according to research published Tuesday in the journal AIP Advances.

smithsonian.com Biologists don't call them " the hidden kingdom" for nothing. With an estimated 5 million species, only a mere 100,000 fungi are known to scientists. This kingdom, which includes molds, yeasts, rusts and mushrooms, receives far less attention than plants or animals.