All the matter you’ve ever interacted with has mass, and as such it obeys the standard laws of motion as enunciated by Newton centuries ago. If you push something, it moves in the direction you push it. However, matter with negative mass would do the opposite. It sounds like wacky science fiction, but it’s close to becoming reality. Researchers at the University of Rochester have worked out a way to create negative mass particles using, what else, lasers. Is there anything lasers can’t do?
Physicists have been chasing real-world examples of negative mass for years, but it’s all been theoretical until recently. The math predicted negative mass was possible, though. In the classic physics equation for force (F = ma), all three variables are positive. However, if you make mass a negative number, the resulting force is negative as well. Thus, pushing an object with negative mass causes it to accelerate toward you. Try to pull it toward you and it’ll move away. It’s a real mind-bender.
The University of Rochester team says the new experiment published in Nature Optics is the first example of creating particles that exhibit negative mass. In the experiment, a laser bounces off mirrors within a small optical cavity. The key to generating negative mass particles was the use of an ultra-thin semiconductor made of molybdenum diselenide. The photos on the laser and excitons in the semiconductor then interact to produce the negative mass effects.
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