Negative mass, a concept that mostly remained in the realm of speculative theories, has been physically observed by scientists from the Washington State University.
The concept got traction by enthusiasts who argue that since electric charges can be positive or negative, then the matter can also take up positive or negative mass.
Proponents of the existence of negative mass were using it as a tool for interpreting wormholes, which are cosmological tunnels supposed to exist between two points of the universe.
The conceptual patronage for wormholes came from physicists such as Ludwig Flamm, Albert Einstein, and Nathan Rosen, who believed that black holes are stretchable and envisaged their inter-linkages with implications of negative mass properties for such transits.
A wormhole has no observational evidence to back it. In theory, it is considered the medium of intergalactic travel.
However, negative mass completely overturns the conventional laws of motion. The Newton's laws of motion state that when an object is pushed, acceleration works in the direction to which the object has been shoved.
"With negative mass, if you push something, it accelerates toward you," said Michael Forbes, a physicist at Washington State University and co-author of the paper.
That means an object with negative mass is defying laws of motion, which hold force as a product of mass multiplied by the acceleration (F=ma) of the object, and acting in the reverse direction.
The concept of negative mass was fist propounded by physicist Hermann Bondi in a paper published in 1957. He argued that negative mass is a possibility given that there are negative electric charges.
Experiments With Bose-Einstein Condensate
In creating the preliminary conditions required for observing negative mass, the team led by Peter Engels of Washington State University (WSU) cooled rubidium atoms just above the temperature of absolute zero, close to -273C for making the Bose-Einstein Condensate.
In the BEC state, the particles will move slowly and act like waves in accordance with quantum mechanics. In the superfluid state, the flow will be without loss of energy.
In the next step, the researchers used lasers to kick the rubidium atoms back and forth for making changes in the way they were spinning.
The BEC, when agitated by lasers showed a tendency to rush out of the web with negative mass.
"Once you push, it accelerates backward," said Forbes and noted the rubidium was behaving as if it was hitting an invisible wall.
After releasing atoms from the laser trap, they were found expanding and displaying negative mass properties.
Study Of Cosmological Phenomena To Benefit
In the experiment, the WSU researchers made sure that past defects did not constrain the experiment as in previous attempts while trying to understand negative mass.
"What's a first here is the exquisite control we have over the nature of this negative mass, without any other complications," said Forbes.
The new research is expected to trigger more studies in astrophysics, neutron stars, dark energy, and black holes. Forbes said the experiment will provide the right guidance for environments in studying the peculiar phenomenon.
The study has been published in the Physical Review Letters.