Negative mass particles created in WSU experiment

Study matter and its motion through spacetime...

Moderators: Calilasseia, ADParker

Negative mass particles created in WSU experiment

#1  Postby Blackadder » Apr 19, 2017 5:00 pm

I confess my knowledge of physics is too puny to fully understand how it works, but the phenomenon sounds mighty intriguing.

From the BBC

http://www.bbc.co.uk/news/science-environment-39642992

Physicists have created a fluid with "negative mass", which accelerates backwards when pushed.
In the everyday world, when an object is pushed, it accelerates in the same direction as the force applied to it; this relationship is described by Isaac Newton's Second Law of Motion.
But in theory, matter can have negative mass in the same sense that an electric charge can be positive or negative.
The phenomenon is described in Physical Review Letters journal.
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.
When the atoms were released from the laser trap, they expanded, with some displaying negative mass.


The full paper is here (behind a paywall unfortunately):

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.155301
That credulity should be gross in proportion to the ignorance of the mind that it enslaves, is in strict consistency with the principle of human nature. - Percy Bysshe Shelley
User avatar
Blackadder
RS Donator
THREAD STARTER
 
Posts: 3673
Male

United Kingdom (uk)
Print view this post

Ads by Google


Re: Negative mass particles created in WSU experiment

#2  Postby newolder » Apr 19, 2017 5:23 pm

Also available through the arxiv

I'm not a condensed matter guy but the idea of negative mass and positive buoyancy may have some parallels. :dunno:

For example, the behaviour of a buoyant, tethered helium-filled balloon seems counter-intuitive, at first.
Geometric forgetting gives me loops. - Nima A-H
User avatar
newolder
 
Name: Albert Ross
Posts: 6471
Age: 8
Male

Country: Feudal Estate number 9
Print view this post

Re: Negative mass particles created in WSU experiment

#3  Postby crank » Apr 19, 2017 6:13 pm

I thought I saw somewhere that there were huge implications if negative mass was possible?
“When you're born into this world, you're given a ticket to the freak show. If you're born in America you get a front row seat.”
-George Carlin, who died 2008. Ha, now we have human centipedes running the place
User avatar
crank
RS Donator
 
Name: Sick & Tired
Posts: 10362
Age: 4
Male

Country: 2nd miasma on the left
Pitcairn (pn)
Print view this post

Re: Negative mass particles created in WSU experiment

#4  Postby twistor59 » Apr 19, 2017 6:24 pm

https://physics.stackexchange.com/questions/327450/negative-mass-or-just-the-appearance-of-negative-mass-whats-the-acid-test

The 'negative mass' referred to in the paper is effective mass. The idea is that while every fundamental constituent of a physical system has a known, nonnegative mass, the effective degrees of freedom of the system may behave as if they have a different mass.
A soul in tension that's learning to fly
Condition grounded but determined to try
Can't keep my eyes from the circling skies
Tongue-tied and twisted just an earthbound misfit, I
User avatar
twistor59
RS Donator
 
Posts: 4966
Male

United Kingdom (uk)
Print view this post

Re: Negative mass particles created in WSU experiment

#5  Postby crank » Apr 19, 2017 7:05 pm

That's a way the fuck NOT creating negative mass particles then. The 'holes' we used to work with semiconductor calculations are as 'bizarre' as this. While the holes are said to have a positive charge, that makes a lot more sense than saying these things have negative mass, at least to me. The closest the abstract, or the OP I should say, came to using anything like 'effective' is when it said 'displaying negative mass'. I think the paragraph is poorly worded making it misleading. Just my opinion, and I am a crank after all.
“When you're born into this world, you're given a ticket to the freak show. If you're born in America you get a front row seat.”
-George Carlin, who died 2008. Ha, now we have human centipedes running the place
User avatar
crank
RS Donator
 
Name: Sick & Tired
Posts: 10362
Age: 4
Male

Country: 2nd miasma on the left
Pitcairn (pn)
Print view this post

Re: Negative mass particles created in WSU experiment

#6  Postby The_Metatron » Apr 19, 2017 7:09 pm

Holes? The navy used to teach their techs that shit. We airmen learned how the electrons flow.


Sent from my iPad using Tapatalk
I AM Skepdickus!

Check out Hack's blog, too. He writes good.
User avatar
The_Metatron
Moderator
 
Name: Jesse
Posts: 20608
Age: 56
Male

Country: United States
United States (us)
Print view this post

Re: Negative mass particles created in WSU experiment

#7  Postby crank » Apr 20, 2017 6:45 am

You had techs working with internal semi-conductor physics? Were they trying to fix transistors by redoping them in the field? That would indeed be impressive.
“When you're born into this world, you're given a ticket to the freak show. If you're born in America you get a front row seat.”
-George Carlin, who died 2008. Ha, now we have human centipedes running the place
User avatar
crank
RS Donator
 
Name: Sick & Tired
Posts: 10362
Age: 4
Male

Country: 2nd miasma on the left
Pitcairn (pn)
Print view this post

Ads by Google


Re: Negative mass particles created in WSU experiment

#8  Postby DavidMcC » May 01, 2017 10:32 am

crank wrote:I thought I saw somewhere that there were huge implications if negative mass was possible?

Indeed there would. If an ACTUAL (as opposed to solid state effective) particle mass was negative, space itself would probably be destroyed, assuming E = m * C2, so that the presence of the particle would require less energy than its absence!

EDIT: It think the thread title is highly misleading, because solid state effective mass is NOT actual particle mass - it is strongly dependent on the periodic lattice in which the carrier moves. It is this periodicity that entirely causes the "negative mass", when no actual particles with negative mas are involved.
This topic pops up from time to time, as people who have no background in solid state physics read about "negative mass".
As they say: "a little knowledge is a dangerous thing".

FURTHER EDIT: Even superfluids do not involve actual negative mass particles. As with solid state, it is particle-particle interactions that create the effect.
May The Voice be with you!
DavidMcC
 
Name: David McCulloch
Posts: 14913
Age: 66
Male

Country: United Kigdom
United Kingdom (uk)
Print view this post

Re: Negative mass particles created in WSU experiment

#9  Postby theropod » May 01, 2017 1:33 pm

Doesn't Hawking Radiation depend on virtual particles? If virtual particles exists, and some evidence suggest they do, when they recombine to destroy each other surely a positive and negative assignment must exist or they would not be destoryed in recombination. Just asking, don't have a meltdown if I am out of my element.

RS
Sleeping in the hen house doesn't make you a chicken.
User avatar
theropod
RS Donator
 
Name: Roger
Posts: 7529
Age: 65
Male

Country: USA
United States (us)
Print view this post

Re: Negative mass particles created in WSU experiment

#10  Postby DavidMcC » May 01, 2017 1:51 pm

theropod wrote:Doesn't Hawking Radiation depend on virtual particles? If virtual particles exists, and some evidence suggest they do, when they recombine to destroy each other surely a positive and negative assignment must exist or they would not be destoryed in recombination. Just asking, don't have a meltdown if I am out of my element.

RS

That is correct, but virtual particles are only constructs - they don't actually exist.
May The Voice be with you!
DavidMcC
 
Name: David McCulloch
Posts: 14913
Age: 66
Male

Country: United Kigdom
United Kingdom (uk)
Print view this post

Re: Negative mass particles created in WSU experiment

#11  Postby DavidMcC » May 01, 2017 1:58 pm

On superfluid flow: many years ago, there were claims published that superfluids flow uphill. What I think must have actually been happening is that they were literally "bouncing out" of a test tube (rather than defying gravity ) after being poured in.
Last edited by DavidMcC on May 01, 2017 3:05 pm, edited 1 time in total.
May The Voice be with you!
DavidMcC
 
Name: David McCulloch
Posts: 14913
Age: 66
Male

Country: United Kigdom
United Kingdom (uk)
Print view this post

Re: Negative mass particles created in WSU experiment

#12  Postby theropod » May 01, 2017 2:41 pm

DavidMcC wrote:
theropod wrote:Doesn't Hawking Radiation depend on virtual particles? If virtual particles exists, and some evidence suggest they do, when they recombine to destroy each other surely a positive and negative assignment must exist or they would not be destoryed in recombination. Just asking, don't have a meltdown if I am out of my element.

RS

That is correct, but virtual particles are only constructs - they don't actually exist.


Damn, I am really confused now.


Thus virtual particles are indeed real and have observable effects that physicists have devised ways of measuring. Their properties and consequences are well established and well understood consequences of quantum mechanics.


From HERE.

RS
Sleeping in the hen house doesn't make you a chicken.
User avatar
theropod
RS Donator
 
Name: Roger
Posts: 7529
Age: 65
Male

Country: USA
United States (us)
Print view this post

Re: Negative mass particles created in WSU experiment

#13  Postby DavidMcC » May 01, 2017 2:59 pm

Roger, it may be that virtual particles can be regarded as "real for a fleeting instant", but it is an odd form of reality when they are required to vanish in an instant, and may defy the laws of physics as they pertain to "really real" particles that continue to exist for much longer (even if they decay fairly quickly - at least they obey the conservation laws both before and after decay!). Also, I am a little sceptical of assurances that the Casimir effect is proof to the reality of virtual particles.

EDIT: Also, Hawking radiation has never been shown to occur - real black holes are way, way too big to evaporate in a reasonable time.
FURTHER EDIT: I believe it has been shown that astronomical black holes invariably accrete matter much faster than they could possibly lose it by Hawking radiation, even in the high vacuum of deep space.
May The Voice be with you!
DavidMcC
 
Name: David McCulloch
Posts: 14913
Age: 66
Male

Country: United Kigdom
United Kingdom (uk)
Print view this post

Re: Negative mass particles created in WSU experiment

#14  Postby theropod » May 01, 2017 3:36 pm

I know. This is why I am having issues wrapping my head around this whole subject.

RS
Sleeping in the hen house doesn't make you a chicken.
User avatar
theropod
RS Donator
 
Name: Roger
Posts: 7529
Age: 65
Male

Country: USA
United States (us)
Print view this post

Re: Negative mass particles created in WSU experiment

#15  Postby DavidMcC » May 01, 2017 4:05 pm

Roger,
it seems that the Casimir effect is on firmer ground than I thought:
http://math.ucr.edu/home/baez/physics/Quantum/casimir.html
The Casimir effect is a small attractive force that acts between two close parallel uncharged conducting plates. It is due to quantum vacuum fluctuations of the electromagnetic field.
The effect was predicted by the Dutch physicist Hendrick Casimir in 1948. According to the quantum theory, the vacuum contains virtual particles which are in a continuous state of fluctuation (see physics FAQ article on virtual particles). Casimir realised that between two plates, only those virtual photons whose wavelengths fit a whole number of times into the gap should be counted when calculating the vacuum energy. The energy density decreases as the plates are moved closer, which implies that there is a small force drawing them together.
The attractive Casimir force between two plates of area A separated by a distance L can be calculated to be,

π h c
F = ------- A
480 L4

where h is Planck's constant and c is the speed of light.
The tiny force was measured in 1996 by Steven Lamoreaux. His results were in agreement with the theory to within the experimental uncertainty of 5%.
Particles other than the photon also contribute a small effect but only the photon force is measurable. All bosons such as photons produce an attractive Casimir force while fermions make a repulsive contribution. If electromagnetism was supersymmetric there would be fermionic photinos whose contribution would exactly cancel that of the photons and there would be no Casimir effect. The fact that the Casimir effect exists shows that if supersymmetry exists in nature it must be a broken symmetry
According to the theory the total zero point energy in the vacuum is infinite when summed over all the possible photon modes. The Casimir effect comes from a difference of energies in which the infinities cancel. The energy of the vacuum is a puzzle in theories of quantum gravity since it should act gravitationally and produce a large cosmological constant which would cause spacetime to curl up. The solution to the inconsistency is expected to be found in a theory of quantum gravity.

However, see the last para. of my quote!
May The Voice be with you!
DavidMcC
 
Name: David McCulloch
Posts: 14913
Age: 66
Male

Country: United Kigdom
United Kingdom (uk)
Print view this post

Ads by Google


Re: Negative mass particles created in WSU experiment

#16  Postby DavidMcC » May 01, 2017 4:12 pm

... Also, I wonder whether this experimental result has ever been independently verified. I guess it would be very difficult to achieve an adequate vacuum with such a small plate gap.
May The Voice be with you!
DavidMcC
 
Name: David McCulloch
Posts: 14913
Age: 66
Male

Country: United Kigdom
United Kingdom (uk)
Print view this post

Re: Negative mass particles created in WSU experiment

#17  Postby theropod » May 01, 2017 4:21 pm

I obviously need to spend some time reading about this as I am now more confused than ever. There's a reason theoretical physicists spend a lifetime thinking about this stuff. Thanks for trying DavidMC, but it's a case of old dogs learning new tricks.

RS
Sleeping in the hen house doesn't make you a chicken.
User avatar
theropod
RS Donator
 
Name: Roger
Posts: 7529
Age: 65
Male

Country: USA
United States (us)
Print view this post

Re: Negative mass particles created in WSU experiment

#18  Postby crank » May 02, 2017 10:42 pm

I wish I had the citation handy, I think it was newolder who posted it, a piece on fields and how virtual particles are not really particles, the fields are entirely different. They sorta act/appear like particles but fundamentally are a different beast.
“When you're born into this world, you're given a ticket to the freak show. If you're born in America you get a front row seat.”
-George Carlin, who died 2008. Ha, now we have human centipedes running the place
User avatar
crank
RS Donator
 
Name: Sick & Tired
Posts: 10362
Age: 4
Male

Country: 2nd miasma on the left
Pitcairn (pn)
Print view this post

Re: Negative mass particles created in WSU experiment

#19  Postby DavidMcC » May 03, 2017 10:40 am

crank wrote:I wish I had the citation handy, I think it was newolder who posted it, a piece on fields and how virtual particles are not really particles, the fields are entirely different. They sorta act/appear like particles but fundamentally are a different beast.


That would make sense, because I don't think that real negative mass particles are feasible, with physics as we know it.
Perhaps newolder could find the citation.
May The Voice be with you!
DavidMcC
 
Name: David McCulloch
Posts: 14913
Age: 66
Male

Country: United Kigdom
United Kingdom (uk)
Print view this post

Re: Negative mass particles created in WSU experiment

#20  Postby newolder » May 03, 2017 11:09 am

crank wrote:I wish I had the citation handy, I think it was newolder who posted it, a piece on fields and how virtual particles are not really particles, the fields are entirely different. They sorta act/appear like particles but fundamentally are a different beast.

This one, perhaps? https://arxiv.org/abs/1204.4616
Quantum foundations are still unsettled, with mixed effects on science and society. By now it should be possible to obtain consensus on at least one issue: Are the fundamental constituents fields or particles? As this paper shows, experiment and theory imply unbounded fields, not bounded particles, are fundamental. This is especially clear for relativistic systems, implying it's also true of non-relativistic systems. Particles are epiphenomena arising from fields. Thus the Schroedinger field is a space-filling physical field whose value at any spatial point is the probability amplitude for an interaction to occur at that point. The field for an electron is the electron; each electron extends over both slits in the 2-slit experiment and spreads over the entire pattern; and quantum physics is about interactions of microscopic systems with the macroscopic world rather than just about measurements. It's important to clarify this issue because textbooks still teach a particles- and measurement-oriented interpretation that contributes to bewilderment among students and pseudoscience among the public. This article reviews classical and quantum fields, the 2-slit experiment, rigorous theorems showing particles are inconsistent with relativistic quantum theory, and several phenomena showing particles are incompatible with quantum field theories.

I don't see how this relates to negative mass though. :dunno:
Geometric forgetting gives me loops. - Nima A-H
User avatar
newolder
 
Name: Albert Ross
Posts: 6471
Age: 8
Male

Country: Feudal Estate number 9
Print view this post

Next

Return to Physics

Who is online

Users viewing this topic: No registered users and 1 guest