Negative Mass : A Hypothetical Matter

(Last Updated On: January 27, 2018)

What is negative mass?

In theoretical physics, negative mass is a matter whose mass is of opposite sign to the mass of normal matter. Such matter would violate one or more energy conditions and show some strange properties. It is used in certain speculative theories, such as on the construction of wormholes. Originally the closest known real representative of such matter is a region of negative pressure density produced in Casimir Effect.


negative mass


Newton’s law of motion, f=ma, dictate that pushing an object will accelerate in the direction in which it was pushed. Our everyday world sees only the positive aspects of Newton’s 2nd law of motion. But in case of mass with negative sign if we push such thing it accelerates towards us just like it hits an invisible wall. Just as electric charge can be either positive or negative, matter could hypothetically, have either positive or negative mass.


Source of idea of negative mass

Cosmologists have examined the effect that it would have on the structure of space-time but they generally conclude that negative matter can not exist as it breaks essential assumption of Einstein’s theory of general relativity. However scientists at university of Canada found a solution to general relativity that allows negative mass, without breaking any essential assumptions. They suggest that it can exist, provided there is a reasonable mechanism for producing it. Their conclusion point out that if positive and negative mass exists simultaneously, they would form plasma which would have important implications for future of astronomy.


negative mass


Recently, physicist Peter Angles and a team at Washington state university have created a fluid with negative mass.Unlike every physical object in the world we know,it doesn’t accelerate in the direction it is pushed,it accelerates backwards i.e. in the direction opposite of force applied.The phenomenon is rarely created in laboratory conditions and can be used to explore some more challenging concepts.


Related experiment and conditions

The latest study provides a new platform to study this hypothetical form of matter. By showing that under certain precise conditions, normal particles can be made to behave like they had mass with negative sign. On 10 April, 2017 the team created new “effective” mass by reducing the temperature of rubidium atoms near just to absolute zero. It is called Bose-Einstein condensate. In this cooled state particles move extremely slowly. At this point the rubidium super fluid has regular mass. It follows principles of quantum mechanics and behaves like waves. This state of matter is known as super fluidity, in which a liquid can creep up the sides of jars and over the top. By using a laser trap, the team were able to reverse the spin of some of the rubidium atoms in this state. Then they observed that once released from the trap, the atoms expanded and displayed properties of negative mass, in particular accelerating towards a pushing force instead of away from it.

negative mass

Some recent work with meta materials suggests that some undiscovered composite of superconductors also could show the signs of negative mass.

Summing up all above stated,theoretically this sounds straightforward,but picturing how this behaviour  would work in the real world is bewildering.Although in real world all particles are considered to have positive mass for convenience, but physicists have been able to associate negative mass of exotic matter with negative momentum,negative pressure,negative kinetic energy and faster than light phenomena.

So mind it if someone push you and you move towards the opposite direction then you may be made of negative mass!!!

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