Scientists create fluid that seems to defy physics

Imagine somethingthat reacts totally opposite to the way it should.That's what scientists at Washington State University have created, and it could help them better understand our universe.

When we push on an object, we know intuitively that adhering to Isaac Newton's Second Law of Motion it will move away. Butimagine taking your child to the park, putting him or her on a swing and pushing only to have the swing move toward you and not away.

Physicists at Washington State University (WSU) have created a fluid with this sort of property,called a negative mass.

How it was created

The theory of negative mass has been around for some time. Just like an electric charge can be positive or negative, it isbelieved the same should hold true for mass. But no such naturally occurring substance has ever been found.

The researchers at WSU were able to create it by using a laser to coolrubidium atoms to just above absolute zero (273 C). This slows the atoms to the point where they're almost immobile, called a superfluid. And, as opposed to moving as individual atoms, they act as one, moving as a wave, as predicted by quantum mechanics. If the atoms were released , they would rush out as expected.

However, then a second laser was applied that changed the way the atoms spin. Once the rubidium rushed out, itacted as though it had hit a walland accelerated backward.

"It's just strange. You push something and you see it go in the wrong direction," said Canadian researcherMichael Forbes of WSU, and co-author of thestudy."It's a new way of studying physics here, and a phenomenon that's reallycounterintuitiveto everydaylife."

And while it does seem counterintuitive, it's not a violation of physics.

"It's not like we violated some laws of physics," Forbes said. "These objects are not going to create a black hole or anything like that."

Practical applications

Forbes said creating negative mass allows him to study matter that he's unable to study in any other way. His studies focus around neutron stars, small and extremely dense stars. The neutrons in the crust of the star form a superfluid similar to the ones created in this kindofexperiment. This can help answer questions as to why the neutron in these stars behave the way they do.

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This creation may have practical applications as well.

"Once new quantum ideas and phenomenon are discovered, there's a fairly short timescalebefore those tend to be developed into quantum technologies which can be used to create high-precision measurements or improve navigational devices and things like that," Forbes said.

For example, earlier experiments have resulted in our phones having compasses.

And there's a lot of money being put into developing quantum technology, he said.

As to what possible technologies this new creation may lead to, Forbes said it's too early to tell.

"We don'tknow where this is going yet but once you start understanding these behaviours, then you can use them to engineer devices, engineer measurement techniques, and then they can find their way into consumer devices."