13 mai 2017

Un fluide qui possède une "masse négative"

Quelle fascinante découverte:

Changing a particle’s spin changes how it behaves and interacts with its environment, so the WSU manipulators once again used lasers to alter the spin of these considerably chilly rubidium nuclei.

Ultimately, this caused them to behave as if they had negative mass.

(...) This team appear to have created negative mass, in that it behaves in very much the opposite way to normal mass. If you push a ball, the momentum you impart upon it pushes it forwards in the direction of applied force.

This new rubidium fluid moves backwards when you push it, because it apparently has negative mass. In reality, this is not true negative mass, but something called negative effective mass, which is mass that behave as if it is negative mass (...)

It’s likely that negative mass already exists elsewhere, but as reported in the journal Physical Review Letters, this experiment allows the researchers to carefully control a version of it and probe its characteristics. The new fluid also opens up a new avenue of analysis for strange astronomical features, like black holes and dark energy, which cannot be directly experimented with.

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