Newton’s Second Law of Motion states that “The acceleration of an object produced by a net force is directly proportional to the magnitude of the net force and in the same direction as the net force”. In simple terms it means that when we push an abject, it will accelerate in the direction that we push it in.
That is how mass generally behaves. Until now, that is. Physicists at the Washington State University have created a fluid that displays negative mass- when one pushes it, the substance bizarrely doesn’t accelerate in the direction it is pushed. It accelerates backwards, towards the person pushing it.
In our everyday world, we are used to things moving away from us when pushed, and moving closer to us when pulled.
“That’s what most things that we’re used to do,” said Michael Forbes, a WSU assistant professor of physics and astronomy and an affiliate assistant professor at the University of Washington. “With negative mass, if you push something, it accelerates toward you.” Mr Forbes was part of the team that made the discovery, acting as a theorist analysing the system.
How was this negative mass created?
The WSU team cooled rubidium atoms to just above absolute zero. This resulted in the rubidium atoms turning into the Bose-Einstein Condensate. The Bose-Einstein Condensate (BEC) was first predicted by the scientists Satyendra Nath Bose and Albert Einstein, hence the name.
A Bose-Einstein condensate is a group of atoms cooled to a very low temperature. At that point, the atoms begin to clump together, losing individual identity and becoming identical. The whole group of atoms then starts behaving as though it were a single atom. They synchronize and move in unison in a wave-like motion. The entire mass is known as a superfluid, and this superfluid can flow without losing energy.
The atoms of the BEC thus formed were kicked back and forth until they started spinning backwards. At this stage, the rubidium rushed out at speed and displayed an unusual behaviour- as if it had negative mass.
“Once you push, it accelerates backwards,” said Mr Forbes. “It looks like the rubidium hits an invisible wall,” said Forbes. “What’s a first here is the exquisite control we have over the nature of this negative mass, without any other complications,” he added.
The new discovery is a potent new tool that will enable researchers to conduct experiments regarding the study of analogous physics in astrophysics, like neutron stars, and space phenomena like black holes and dark energy- areas where experimenting has proved to be next to impossible. “It provides another environment to study a fundamental phenomenon that is very peculiar,” Forbes said.
How this new creation can be put to maximum use is a matter of great interest to the scientific community. Until then we can just wait and watch.