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Washington State University physicists have created a fluid with negative mass, which is exactly what it sounds like. Push it, and unlike every physical object in the world we know, it doesn't accelerate in the direction it was pushed. It accelerates backwards.
The phenomenon is rarely created in laboratory conditions and can be used to explore some of the more challenging concepts of the cosmos, said Michael Forbes, a WSU assistant professor of physics and astronomy and an affiliate assistant professor at the University of Washington. The research appears today in the journal Physical Review Letters, where it is featured as an "Editor's Suggestion."
Hypothetically, matter can have negative mass in the same sense that an electric charge can be either negative or positive. People rarely think in these terms, and our everyday world sees only the positive aspects of Isaac Newton's Second Law of Motion, in which a force is equal to the mass of an object times its acceleration, or F=ma. In other words, if you push an object, it will accelerate in the direction you're pushing it. Mass will accelerate in the direction of the force.
takyon: Just what I needed for my Alcubierre drive?
(Score: 5, Informative) by NotSanguine on Tuesday April 18 2017, @06:36AM (4 children)
What AC said.
From TFA:
"Blimey! It's smaller on the outside!"
No, no, you're not thinking; you're just being logical. --Niels Bohr
(Score: 0) by Anonymous Coward on Tuesday April 18 2017, @08:00AM (2 children)
> if behaves as if it has negative mass.
Does nobody notice the if (there is even 2 of them....)?
It seems to me this is not really negative mass, it just behaves as negative mass would behave, seemingly because of some thermodynamic, but not gravitational, force.
But perhaps a physicist can clarify?
(Score: 4, Interesting) by VLM on Tuesday April 18 2017, @12:25PM (1 child)
About 8 years ago PRL had an article titled "Mass of a Spin Vortex in a Bose-Einstein Condensate"
https://arxiv.org/pdf/0902.3685.pdf [arxiv.org]
might be somewhat enlightening. Its a theory paper from about 8 years ago which sounds similar to the experimental results.
(Insert ridiculous levels of hand waving here that would make the paper author cringe if they ever saw it) If you make a vortex in a super fluid its kinda stable which is really weird but well known ish. The vortex itself has a moment of inertia and stores rotating energy and has what boils down to a mass it takes force to mess with a vortex just like it takes peculiar forces depending on rotating speed to mess with a spinning gyroscope which could be abstracted at least instantaneously into a model of just a lump of very heavy metal with a weird moment of inertia shape that isn't rotating. It turns out that superfluid vortexes as they get messed with can under weird circumstances wiggle about on an instantaneous basis as if they were a solid block of steel with negative mass. They aren't of course, the apparatus doesn't lift up into space, but an abstract simulated instantaneous predictive model has a negative number for mass so people get all wound the hell up about it.
An interesting example of negative mass mostly outside this discussion is some hall effect thing where holes wander about as if they are things (rather than lack of things...) that wander about as if they (they as in the hole) have a negative mass.
Another example of negative things that piss people the heck off, is its very easy to build circuitry that essentially emulates a negative resistance. I'll be damned you lower the input voltage and the current goes up what manner of witchcraft is this begone evil spirit. Of course this is merely a boring as hell switching power supply behavior. You graph the behavior of a resistor on a P-I graph paper and you get a hopefully perfectly straight line of a positive resistance welcome to ohms law (although real world resistors do vary with voltage and quite a bit sometimes and also vary with current LOL but close enough to linear most of the time). You graph a nice 100 watt switching power supply with various incoming voltage and current and WTF the damn thing on the graph has a negative resistance. of course the atoms that make it up are entirely positive resistance on a small enough scale... the negative lives in the design of the supply in the system itself. Sorry no bad SN automobile analogy but I did provide you a nice EE analogy so thats not so bad.
In a sense if you were a fish and defined space as having a density of 1 gram per mL which is about right enough for seawater (to one sig fig anyway) and you worked out all manner of gravitational theory you'd be confused as hell about cavitation bubbles if you ever saw one. So water has a density of zero and this "hole in the water" has a density of -1 grams per mL wtf? And you only get cavitation bubbles by spinning a propeller faster than the speed of sound essentially? Weird.
The whole topic is sort of like trolling/provoking people using the light year long scissors and no part of the scissors ever moves faster than 1 m/s but the intersection point of the two blades can move an arbitrary multiple of the speed of light by getting the angle just right.
As for what to do with something that isn't flubber but behaves like it in a certain sense, well, I bet you could make a rube goldberg like seismometer or maybe a gravity wave meter out of a great big volume of it. I wonder if you could tune the virtual mass of a vortex to have very low measurable mass and then very small nearby contaminants like neutrinos would throw it out of balance tada you have a magic nuclear submarine detector. Of course the Navy probably invented, classified, and deployed this 30 years ago but if I disappear, at least you'll know why. It seems like the kind of thing that would be self evident and the magic is all in the engineering, kind of like a nuke, actually.
(Score: 2) by art guerrilla on Tuesday April 18 2017, @01:19PM
whoa, okay...
so was that the blue crystal meth, then ? ??
(Score: 2) by kaszz on Tuesday April 18 2017, @01:15PM
So no closer to the Alcubierre drive then..
Hopefully they succeed to get some data that can improve knowledge to accomplish it though.