In 2001, a British engineer named Roger Shawyer launched something called the EmDrive, which was nicknamed the ‘impossible drive.’ He shared that it could create thrust without carrying any propellant. But, as per physics, you can’t move forward without pushing something backward.
Then in 2016, the Eagleworks team at NASA also detected a bit of thrust from a test version. But in 2021, a study at Germany’s Dresden University of Technology noted that there was no thrust at all.