Washington State University physicists have created a fluid with negative mass, which is exactly what it sounds like. Push it, and unlike every physical object in the world we know, it doesnt accelerate in the direction it was pushed. It accelerates backwards.
The phenomenon is rarely created in laboratory conditions and can be used to explore some of the more challenging concepts of the cosmos, said Michael Forbes, a WSU assistant professor of physics and astronomy and an affiliate assistant professor at the University of Washington. The research appears today in the journal Physical Review Letters, where it is featured as an Editors Suggestion.
Hypothetically, matter can have negative mass in the same sense that an electric charge can be either negative or positive. People rarely think in these terms, and our everyday world sees only the positive aspects of Isaac Newtons Second Law of Motion, in which a force is equal to the mass of an object times its acceleration, or F=ma.
In other words, if you push an object, it will accelerate in the direction youre pushing it. Mass will accelerate in the direction of the force.
Thats what most things that were used to do, said Forbes, hinting at the bizarreness to come. With negative mass, if you push something, it accelerates toward you.
To create negative mass, the researchers applied a second set of lasers that kicked the atoms back and forth and changed the way they spin. Now when the rubidium rushes out fast enough, if behaves as if it has negative mass.
Once you push, it accelerates backwards, said Forbes, who acted as a theorist analyzing the system. It looks like the rubidium hits an invisible wall.
