News: Physicists create negative mass

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SDK
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News: Physicists create negative mass

Postby SDK » Wed Apr 19, 2017 10:12 pm UTC

Physicists have created a fluid with "negative mass" which accelerates towards you when pushed.
or if you prefer
Scientists have created a fluid with negative mass – but what does it tell us?

Prof Peter Engels, from Washington State University (WSU), and colleagues cooled rubidium atoms to just above the temperature of absolute zero (close to -273C), creating what's known as a Bose-Einstein condensate.

In this state, particles move extremely slowly, and following behaviour predicted by quantum mechanics, acting like waves.

They also synchronise and move together in what's known as a superfluid, which flows without losing energy.

To create the conditions for negative mass, the researchers used lasers to trap the rubidium atoms and to kick them back and forth, changing the way they spin.


Weird. I'd heard about this before as something-that's-not-technically-impossible, but never figured we'd actually create the stuff.
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Re: News: Physicists create negative mass

Postby p1t1o » Thu Apr 20, 2017 8:08 am UTC

Apparently this involves negative effective mass, which is not the literal negative mass of our imaginations. Or something.

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Re: News: Physicists create negative mass

Postby Tub » Thu Apr 20, 2017 8:18 am UTC

The paper does not claim anything to have negative mass. That's the result of horrible journalism (and thread titles).

What the paper claims is that (under certain circumstances) the particles behave as if they had a negative m in F=m*a. To put it in a lot less exciting terms:
"Scientists reveal that quantum effects can violate classical laws."


It may still be insightful research (I have no way of telling), but it's not negative mass.

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Re: News: Physicists create negative mass

Postby Link » Thu Apr 20, 2017 7:49 pm UTC

Tub wrote:
The paper does not claim anything to have negative mass. That's the result of horrible journalism (and thread titles).

Yep. This article is interesting in its own right, but wonky effective parameters aren't unusual in quantum systems. The Casimir effect can also be seen as a kind of negative mass.

Unless and until we get clear experimental evidence of a violation of the average null energy condition, "negative mass" isn't something to lose any sleep over.

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Re: News: Physicists create negative mass

Postby Eebster the Great » Thu Apr 20, 2017 11:55 pm UTC

Tub wrote:The paper does not claim anything to have negative mass. That's the result of horrible journalism (and thread titles).

The title of the paper begins with the words "Negative-Mass". I think you are being excessively pedantic here. Yes, obviously there is still positive energy density, but you really do get negative effective inertial mass.

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Re: News: Physicists create negative mass

Postby doogly » Fri Apr 21, 2017 1:11 am UTC

Yeah, there's room for this to be super exciting and for it not to be in anyway inconsistent with what we know about quantum mechanics. And to not be able to make time machines and wormholes out of it. Quantum mechanics is plenty cool, this is totally cool.
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Re: News: Physicists create negative mass

Postby Tub » Fri Apr 21, 2017 8:52 am UTC

Eebster the Great wrote:
Tub wrote:The paper does not claim anything to have negative mass. That's the result of horrible journalism (and thread titles).

The title of the paper begins with the words "Negative-Mass".

One word short. It starts with "negative mass hydrodynamics". Those belong together.

I'm not objecting to the "negative mass" term, I'm objecting to something having negative mass, or to negative mass being created. What's claimed is something behaving as if having negative mass.

The first formulation sounds like you can mass-produce negative mass stuff, pile it up and create wormholes. That's just plain wrong. The second sounds like weird quantum effects doing non-classical things. Which is interesting, but not quite as revolutionary.


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