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E=mc^2 Verified In Quantum Chromodynamic Calculation

kdawson posted more than 4 years ago | from the tee-shirts-were-right-all-along dept.

Supercomputing 268

chirishnique and other readers sent in a story in AFP about a heroic supercomputer computation that has verified Einstein's most famous equation at the level of subatomic particles for the first time. "A brainpower consortium led by Laurent Lellouch of France's Centre for Theoretical Physics, using some of the world's mightiest supercomputers, have set down the calculations for estimating the mass of protons and neutrons, the particles at the nucleus of atoms. ... [T]he mass of gluons is zero and the mass of quarks is only five per cent. Where, therefore, is the missing 95 per cent? The answer, according to the study published in the US journal Science on Thursday, comes from the energy from the movements and interactions of quarks and gluons. ... [E]nergy and mass are equivalent, as Einstein proposed in his Special Theory of Relativity in 1905." Update: 11/21 15:50 GMT by KD : New Scientist has a slightly more technical look at the accomplishment.

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First proton (-1, Offtopic)

Anonymous Coward | more than 4 years ago | (#25846065)

First = MC^2

Re:First proton (0, Redundant)

SimonTheSoundMan (1012395) | more than 4 years ago | (#25846123)

Wow, are /. comments becoming like icanhas, digg or something.

Re:First proton (1)

denis-The-menace (471988) | more than 4 years ago | (#25846469)

You can thank the Idle section for that.

Re:First proton (2, Funny)

idontgno (624372) | more than 4 years ago | (#25846563)

I'm picturing a tiny kitten peering intently at his cute little paw, with a macro over his head reading "My quark has a flavor?"

My proof (5, Funny)

Chapter80 (926879) | more than 4 years ago | (#25847089)

My proof:

We know that e^(pi*i)=-1
and i=Sqrt(-1)
So, to prove that e=mc^2,
we substitute for e, and you get
(mc^2)^(pi*sqrt(-1))=-1 or
(mc^2)^(sqrt(-pi^2)=-1
mc Hammer only had 15 minutes of fame, so squaring that is 225 minutes
If you had a pie, and you squared it off, and I took it from you, and made it round again, you'd have the square root of a negative pie squared.
But this is pi, not pie, so we need to divide by e, which we know is 2.71828...
So 225^(1/2.71828)=-1

I know this worked yesterday... one moment....

Frogs (-1, Offtopic)

Anonymous Coward | more than 4 years ago | (#25846085)

Damn Frogs ... they are good .....

I've only got one thing to say... (-1, Flamebait)

jornak (1377831) | more than 4 years ago | (#25846097)

... no shit, sherlock.

Re:I've only got one thing to say... (-1, Offtopic)

Anonymous Coward | more than 4 years ago | (#25846121)

I second that: No shit, jackasses.

Re:I've only got one thing to say... (-1, Offtopic)

Anonymous Coward | more than 4 years ago | (#25846137)

keep digging watson

Re:I've only got one thing to say... (5, Informative)

underpants_gnome (1226602) | more than 4 years ago | (#25846497)

I wouldn't say that. Not in this case. Just because the equation is "works" in one scale (non-quantum), doesn't mean it works at ALL scales.

Newtonian Mechanics at Relativistic speeds comes is a good example of that.

Re:I've only got one thing to say... (0, Offtopic)

underpants_gnome (1226602) | more than 4 years ago | (#25846547)

comes to mind, and is a good example of that*

Re:I've only got one thing to say... (-1, Offtopic)

Anonymous Coward | more than 4 years ago | (#25846573)

Your sentence construction is "sucks" at this scale.

Re:I've only got one thing to say... (5, Informative)

tonywestonuk (261622) | more than 4 years ago | (#25847273)

Newtonian Mechanics is wrong at any speed. Just the error becomes more noticeable near light speed.

F=MA, yet a 1kg mass accelerated by 10 neutons for 1 second from stationary, will NOT be traveling at 10 m/s
It will be traveling just, very slightly slower....

Anyhow, I thought the actual thought experiment that leads to the derivation of e=mc2, (the one with a photon and a box), assumes the existance of the 'photon' a quantum scale particle.

Re:I've only got one thing to say... (2, Insightful)

Instine (963303) | more than 4 years ago | (#25847307)

and how do you see relativistic speeds as scale restricted? Indeed that is what is being tested here...

So your saying... (1, Funny)

Anonymous Coward | more than 4 years ago | (#25846111)

Cowboy Neal isn't 'heavy set', he is just full of energy?

Re:So your saying... (1)

The Gaytriot (1254048) | more than 4 years ago | (#25846561)

Literally.

He just has tons of energy stored up for later use.

Re:So your saying... (1)

Muad'Dave (255648) | more than 4 years ago | (#25847117)

I've always wondered how long I'd burn if you stuck a wick in me and lit it.

Pretty cool (2, Insightful)

grub (11606) | more than 4 years ago | (#25846119)


All that computing power to verify what Einstein figured out with his head and a chalkboard.

Re:Pretty cool (4, Insightful)

bradkittenbrink (608877) | more than 4 years ago | (#25846173)

To me, it sounds more like verifying that Quantum Chromodynamics isn't inconsistent...

Re:Pretty cool (0)

Anonymous Coward | more than 4 years ago | (#25846247)

Good point. It /is/ useful if you view it as verifying Quantum Chromo-dynamics. But for them to say they "verified" Einstein's equation is ridiculous... Almost laughable.

Re:Pretty cool (2, Insightful)

Edward Kmett (123105) | more than 4 years ago | (#25846315)

It is remarkable in the fact that all of the previous attempts to mix Quantum-"anything" with Relativity have pretty much spectacularly failed.

I'm quite impressed.

Re:Pretty cool (4, Informative)

caramelcarrot (778148) | more than 4 years ago | (#25846479)

Since E=mc^2 is a result of special relativity, and special relativity has been a feature of quantum mechanics since the Dirac equation, no, special relativity+QM has been spectacularly successful. GR and QM is slightly more problematic, but irrelevant to the issue.

Re:Pretty cool (1)

Amazing Quantum Man (458715) | more than 4 years ago | (#25847037)

Yep. Electron spin is a purely relativistic phenomenon. It can't be derived from "classical" QM.

Re:Pretty cool (2, Informative)

Anonymous Coward | more than 4 years ago | (#25847303)

That's not true, actually. But it's a very commonly held misconception.

Spin is not a relativistic phenomenon in itself, although it does arise naturally from the Dirac equation. It is not even a QM property in itself; It can be viewed physically as a circulating energy flow in the wave field of the electron. This was shown by Belinfante in 1939.

If you're interested, see, e.g. "What is Spin?" Ohanian, Am J Phys, 54(6), 500-505

Re:Pretty cool (1)

who knows my name (1247824) | more than 4 years ago | (#25847157)

special relativity and QM still aren't fully integrated, even after the Dirac Equation. Any further unification of the two theories is an important step towards quantum relativity (and hopefully in the long run, quantum gravity).

Re:Pretty cool (1)

The_Wilschon (782534) | more than 4 years ago | (#25847333)

Uhhh, yes they are. Quantum field theories are exactly quantum theories with Lorentz symmetry. They are, as the GP said, spectacularly successful. QCD is one of them. Disclaimer: IAAPGS (Physics Grad Student)

Re:Pretty cool (1)

marcosdumay (620877) | more than 4 years ago | (#25846521)

You mean, like Dirack did at the 20's? (Or was it at the 30's? I don't remeber.) Or like all kinds of nuclear, x-ray, and particle physics? None of those failed.

If we couldn't mix quantum-anything with relativity, one of those theories (maybe both) would have be disproved a long time ago. If there is something that makes people crazy is exaclty that those theories are consistent in all kinds of experiments that we are able to do, but not ont theory.

Re:Pretty cool (1)

Cyberax (705495) | more than 4 years ago | (#25846875)

Wrong.

The first relativistic extension of Schroedinger equation (http://en.wikipedia.org/wiki/Klein-Gordon_equation) has been derived in 1926.

We can't reconcile General Relativity and quantum field theories, but special relativity in quantum mechanics has been used quite successfully for quite a long time.

Re:Pretty cool (5, Informative)

evanbd (210358) | more than 4 years ago | (#25846209)

Not really the same thing. Einstein derived it for non-quantum objects (ie large ones, or ones for which we can otherwise ignore quantum effects). This team verified it for quantum objects. This is interesting because the two theories don't mesh well -- one works at small scales and the other at large scales. It's not a theory of everything, because it doesn't touch gravity, but it's important to know where precisely the region the two are in conflict is. This calculation helps map that border.

Re:Pretty cool (1)

zappepcs (820751) | more than 4 years ago | (#25846459)

Exactly. Well said. When we manage to solve the difference between the theories we now have, we should end up with the theory of everything. Perhaps then we'll all get our flying cars, and so everyone will know how to skydive.

I wonder how much more compute power we'll need to get some facts behind the eventual theory of everything, and will it's name be '42'?

Re:Pretty cool (1)

Jason Levine (196982) | more than 4 years ago | (#25846977)

Perhaps then we'll all get our flying cars, and so everyone will know how to skydive.

If a flying car is so unsafe that you are required to know how to skydive, I don't think I want to drive one!

Re:Pretty cool (3, Informative)

caramelcarrot (778148) | more than 4 years ago | (#25846489)

Once again, you're confused between special relativity (which QM meshes well with) and GR, which it doesn't. E=mc^2 is a result of special relativity, and so this isn't wholly suprising.

Re:Pretty cool (0)

Anonymous Coward | more than 4 years ago | (#25846511)

E = m * c^2 comes from the special relativistic theory, which mixes very well with quantum mechanics (for example the Dirac equations are a relativistic formulation of quantum mechanics).

SRT also works independently of scales, because it just looks at frames of references and their relation, and doesn't care about absolute sizes of objects.

Re:Pretty cool (1)

hypomorph (1305401) | more than 4 years ago | (#25847067)

Exactly, its only the inclusion of gravity within the perspective of special relativity (which is called general relativity) that causes problems with quantum mechanical formulations.

Re:Pretty cool (1, Funny)

Anonymous Coward | more than 4 years ago | (#25846691)

There is no gravity the universe sucks.

Re:Pretty cool (0)

Anonymous Coward | more than 4 years ago | (#25846927)

Also not really the same thing, and on the other hand the same thing: Leibniz already knew this formula: vis viva = mv2 (link [wikipedia.org] )

Re:Pretty cool (1)

ceoyoyo (59147) | more than 4 years ago | (#25847221)

Actually, the summary, and presumably the article it quotes, mangle to point into unrecognizability. The New Scientist article is much better.

The interesting point, though well recognized, is that most of the mass of hadrons comes from virtual particles -- most of it from virtual gluons. This research added in virtual quarks and got a result closer to the real mass - 2% off instead of 10% without the virtual quarks.

E=mc^2 is derived from special relativity, which is a critical component of quantum mechanics. The equation is verified for quantum particles all the time in particle accelerators, and probably has small but measurable effects in that old CRT sitting on your desk.

Re:Pretty cool (4, Insightful)

invisiblerhino (1224028) | more than 4 years ago | (#25846217)

It's not quite that simple. QCD is a quantum field theory, so E=mc^2 is "built in". Really, the point is that experimental results (i.e. proton and neutron mass) are confirmed and a clear explanation for this "mass discrepancy" given. I wouldn't say it's proven, since lattice QCD is a (very very good) approximation to an exact theory.

Re:Pretty cool (0)

Anonymous Coward | more than 4 years ago | (#25846657)

+1 ..ahh what he said...

Re:Pretty cool (3, Insightful)

dkleinsc (563838) | more than 4 years ago | (#25846289)

Einstein may have demonstrated that the math had to be right, but this sort of result was needed to demonstrate that the math correctly described the universe.

Re:Pretty cool (3, Interesting)

u38cg (607297) | more than 4 years ago | (#25846757)

Did Hiroshima not convince you?

Re:Pretty cool (0, Offtopic)

JonDorian88 (1341359) | more than 4 years ago | (#25846313)

Yes, the chalkboard was impressive... But did it run Linux?

Re:Pretty cool (0)

Anonymous Coward | more than 4 years ago | (#25846361)

No. And it didn't support Silverlight neither!

Re:Pretty cool (1)

Ambitwistor (1041236) | more than 4 years ago | (#25846981)

Although the point of the exercise wasn't actually to verify E=mc^2, it was to develop a computer simulation capable of calculating the masses of baryons using quantum chromodynamics. You could write down a formula for them, but nobody had been able to solve it.

Also on Yahoo, (4, Informative)

zeromorph (1009305) | more than 4 years ago | (#25846231)

Also on Yahoo, but with a horrible headline [yahoo.com] . Anyway both just reproduce the AFP text.

The original article seems to be this [sciencemag.org] :

Ab Initio Determination of Light Hadron Masses
S. Dürr, Z. Fodor, J. Frison, C. Hoelbling, R. Hoffmann, S. D. Katz, S. Krieg, T. Kurth, L. Lellouch, T. Lippert, K. K. Szabo, G. Vulvert

Science 21 November 2008:
Vol. 322. no. 5905, pp. 1224 - 1227
DOI: 10.1126/science.1163233

Re:Also on Yahoo, (0)

Anonymous Coward | more than 4 years ago | (#25846263)

Why is it I always read 'Hadron' as 'Hard-on'?

Re:Also on Yahoo, (0)

Anonymous Coward | more than 4 years ago | (#25846387)

Yeah. It's too bad they took Smiling Bob's product off the market. I need to do something about my light hadron mass.

Re:Also on Yahoo, (2, Insightful)

Anonymous Coward | more than 4 years ago | (#25846491)

Because you're a douche bag?

I guess (0)

Anonymous Coward | more than 4 years ago | (#25846267)

It's all relative

This story is useless without a paper. (0)

Anonymous Coward | more than 4 years ago | (#25846277)

As per the title. Is there nothing on arXiv or something for those of us who don't think quarks are Ferengi bartenders?

So the proof is sound, but is it valid? (0)

Anonymous Coward | more than 4 years ago | (#25846279)

So, we've now established that assuming we have a discrete four-dimensional universe, energy and mass are equivalent.

Now prove that this assumption is true, for the win.

Good news, everyone! (4, Funny)

Drakkenmensch (1255800) | more than 4 years ago | (#25846331)

"You fools! You've altered the outcome by observing it!" - Professor Hubert Farnsworth

Re:Good news, everyone! (1, Funny)

Anonymous Coward | more than 4 years ago | (#25846801)

I tried that line on my ex when she surprised me with her sister on her bed. It didn't work.

Mathmatically verifiable (2, Interesting)

fish_in_the_c (577259) | more than 4 years ago | (#25846347)

As I understand it there were several geocentric models of the universe that were mathematically validated.

Am I mistaken or, doesn't that just mean that our theory matches all the known data and the data matches the theory. It Really doesn't have anything to do with whether or not the theory expresses reality.

Re:Mathmatically verifiable (2, Informative)

Andr T. (1006215) | more than 4 years ago | (#25846455)

It Really doesn't have anything to do with whether or not the theory expresses reality.

If you're using Popper's way of doing Science, you'll never know for sure if a theory expresses reality. The theory will be more plausible as it provides data about the reality and when it shows correct predictions about observable facts.

Re:Mathmatically verifiable (3, Interesting)

fish_in_the_c (577259) | more than 4 years ago | (#25847149)

Hadn't heard of him before. That is truly fascinating. It almost appears to have come full circle.
Prior to Galileo, scientists never made the assumption that their theory actually had correspondence to reality. They were mostly concerned with whether or not it corresponded to the data and considered a theory 'true' if it corresponded to the existing data and had predictive power. There was a phrase which was used to mean that but I can't remember it right now.
'conservation of aspects' 'preservation of aspects' something like that.

I once read a work by Hippocrates called which I believe was titled: 'advice to traveling physicians'

In it he begins by explaining that a traveling physician should take into account the environment of the town he is about to enter, because it will help him predict the type of diseases likely to exist in the population.

He then enumerates different environments and diseases.

For example he predicted , correctly , that people living in areas where there were 'strong seasonal winds' --- I assume monsoons, had a higher number of stomach related ailments. He noted this was most likely because they tended to drink brackish or salty water. He then explained that the reason for the stomach problems was because the salt made their heads soft and caused the phlegm to run into their stomach, which also explained why they tended to be much stupider then the rest of the world.

I think it makes that makes an interesting example how the 'testable' part of a theory can be completely correct and useful for predictiveness and the 'un-testable' part of the model can by wholly wrong.

That being said there are a lot of people trying to do silly things like , prove God does or doesn't exist using science or prove people do or don't have immortal souls or free will.

The problem comes in of coarse with testability and shows that science, while incredibly useful as a tool to the race, simply has it's limits which it is unlikely to easily transcend and are of coarse tied to our ability to gather, and interpret data.

Questions like whether or not God exists are simply outside the realm of science proper, because of the ability to gather sufficient and repeatable data with proper controls.
That includes, however, both the positive and negative answer. I have never quite understood the instance, some people seem to have, that you cannot prove God exists while insisting it is possible to prove he doesn't.

Re:Mathmatically verifiable (0)

Anonymous Coward | more than 4 years ago | (#25846765)

Well, you're wrong.

Sure, you can make a geocentric mathematical model that works. But it means the planets will be moving in extremely strange trajectories, doubling back on themselves, etc. Basic classical physics would reject such an explanation.

So either you go with the simpler, heliocentric model which fits with physics as we know it. Or do you choose the more complicated one that would invalidate everything we think we know about how things move? Obviously the theories are not on equal footing.

But even if they were on equal footing with respect to physics, the oft-misunderstood Occam's Razor would come into play. Given two _equally acceptable_ theories, we choose the simpler one.

Whether or not the theory reflects 'reality' or not is a moot point. For all practical intents and purposes, reality is what can be measured. The data IS reality. If a model fits all known data, then it's 'reality' as we know it. If several models do, then that is the realm of research. Find a point of difference between the models and construct an experiment to get new data to determine which one is correct.

If you can't construct such an experiment, then those theories, or at least the area of difference between them isn't scientific. It's metaphysical and of no interest to anybody but teenage philosopher-wannabes.

Re:Mathmatically verifiable (1)

jacekm (895699) | more than 4 years ago | (#25846841)

Geocentric model can be easily mathematically valid. The motion of bodies can be desribed in any coordinate system of ones choice. It just requires more difficult calculations.

JAM

Re:Mathmatically verifiable (0)

Free the Cowards (1280296) | more than 4 years ago | (#25847007)

There's nothing wrong about geocentrism.

The universe has no center, as far as is known. Physical laws work the same in any frame of reference. Choosing the Earth as the center of your coordinate system produces results which are just as correct as any other way.

Such a technique makes astronomical objects a lot harder to work with, but that doesn't make it wrong, merely impractical.

Re:Mathmatically verifiable (4, Insightful)

Ambitwistor (1041236) | more than 4 years ago | (#25847017)

Science can't tell you whether some theoretical construct is "really" there. That's a matter of philosophical definition. All science can tell you is whether the predictions of theories agree with what is observed in the world.

Re:Mathmatically verifiable (1)

Chris Mattern (191822) | more than 4 years ago | (#25847225)

As I understand it there were several geocentric models of the universe that were mathematically validated.

Yes, you can constructed a mathematically consistant model of the universe with the earth as its unmoving center. That's part of the theory of relativity: you can construct a mathematically consistent model of the universe around *any* frame of reference. Since the earth is not an inertial frame of reference, it makes the math needlessly complicated, but you can do it.

Re:Mathmatically verifiable (0)

Anonymous Coward | more than 4 years ago | (#25847269)

Not really.

It means that one theory, based on one model and one set of data (and later verified with additional data) still applies when using a completely different model, based on completely different sets of data.

Thus far, there has been no overlap between relativity, and quantum anything. They describe and model completely different things (gravity versus the strong nuclear force), on completely different scales (very large versus very small).

The news here is that they've managed to actually come up with something that works in both models - namely that mass / energy equivalence also makes sense in terms of quantum chromodynamics.

Silly question... (1)

HAL9000_mirror (1029222) | more than 4 years ago | (#25846419)

If mass translates to energy and energy being lossy, shouldn't the mass of nucleus decrease over time? :-)

Anyway, the article seems to indicate that the energy produced from the interaction between quarks and gluons account for the extra mass. What is to say that the energy produced from the interaction is always the same? If not always the same, it implies that the mass of neutron may vary over period of time!

Btw, the article doesn't care to summarize how the super-computers were used in the proof (except for that last quote in the article).

Re:Silly question... (1)

Neon Aardvark (967388) | more than 4 years ago | (#25846583)

If mass translates to energy and energy being lossy, shouldn't the mass of nucleus decrease over time?

No, because energy isn't ever lost in quantum mechanical bound systems in their ground state.

Re:Silly question... (1, Interesting)

Anonymous Coward | more than 4 years ago | (#25846983)

Energy isn't 'lossy'. The amount of energy (or energy and mass) in the universe is constant.

> What is to say that the energy produced from the interaction is always the same?

Nothing.

> If not always the same, it implies that the mass of neutron may vary over period of time!

It does. In accordance with the uncertainty principle:
deltaE * deltaT >= h-bar/2

Since E = mc^2, you can rewrite that in terms of mass:
deltaM >= h-bar/(2 * c^2 * deltaT)

Where deltaT is the period of time and deltaM is the varation in mass. This applies to everything in the universe equally of course.

When you calculate a quantum-mechanical property, you're always talking about the _expectation value_ of that property. Simply put: The statistical average.

> Btw, the article doesn't care to summarize how the super-computers were used in the proof (except for that last quote in the article).

Well.. not much to say. I involves solving the Dirac equation (the relativistic version of the SchrÃdinger equation). It's a big-ass partial differential equation. As the article notes, they're using a lattice of fixed points. So essentially it's a Finite-Element method, which is a common way of solving differential equations numerically. (Since most of them can't be solved analytically)

Re:Silly question... (4, Informative)

Ambitwistor (1041236) | more than 4 years ago | (#25847113)

It's not solving the Dirac equation (which is for a free fermion), but the full Yang-Mills equations, including the strong nuclear force. And they're not really solving DEs by finite element methods. They're evaluating functional integrals via Monte Carlo (integrating configurations over field space). But the functional to be evaluated (the action) is defined on a spacetime lattice and involves field derivatives, which is where the finite differencing comes in.

Wow, I learned something new... (1)

stangbat (690193) | more than 4 years ago | (#25846429)

For all these years I thought it was E=mc^2. Now I find out it is E=2mc!

Oh dear (2, Funny)

YourExperiment (1081089) | more than 4 years ago | (#25846433)

New Scientist has a slightly more technical look at the accomplishment.

When I read a sentence like that, I begin to wonder if maybe I'm getting my science news from the wrong source.

Re:Oh dear (0)

Anonymous Coward | more than 4 years ago | (#25846979)

If you read Slashdot over New Scientist for science news, then yes you are.

Dark matter (2, Interesting)

Anonymous Coward | more than 4 years ago | (#25846439)

Since the missing mass is from the movement, does this mean anything in the search for dark matter?

Re:Dark matter (0)

Amazing Quantum Man (458715) | more than 4 years ago | (#25847005)

I don't normally go for scatological humor here, but....

Since the missing mass is from the movement, does this mean anything in the search for dark matter?

You usually find the dark matter from the movement in the toilet.

Re:Dark matter (2, Informative)

Ambitwistor (1041236) | more than 4 years ago | (#25847197)

No. They're just verifying that gluons contribute to the binding energy of baryons. A gravitational analogy: we know that the total energy of a binary star system is different from the energy of two random stars millions of light years away from each other. That's because the energy of the system is not just the mass of the stars, but the star masses plus the gravitational energy in the system. For protons, the quarks are like individual stars. We knew that the mass of the proton equals the mass of the quarks plus their binding energy (from the strong force), but until now, we weren't able to calculate that energy.

This doesn't have relevance to dark matter because dark matter can't be due to nuclear binding energy between distant particles: the nuclear force is short ranged.

Ah, so THERE'S the dark matter everyone looks for? (0, Redundant)

waferhead (557795) | more than 4 years ago | (#25846539)

"[T]he mass of gluons is zero and the mass of quarks is only five per cent. Where, therefore, is the missing 95 per cent? The answer, according to the study published in the US journal Science on Thursday, comes from the energy from the movements and interactions of quarks and gluons. "

To repeat what A.C. asked...

This is too obvious to be correct, but perhaps that explains "dark matter"???

(Or is this missing 95% already accounted for somewhere?)

Re:Ah, so THERE'S the dark matter everyone looks f (1)

nedlohs (1335013) | more than 4 years ago | (#25846641)

No, they're saying that 95% of the mass of the normal matter is in fact interaction energy between the subatomic particles.

So 5% or 5% is actually "stuff" :)

Re:Ah, so THERE'S the dark matter everyone looks f (1)

jfengel (409917) | more than 4 years ago | (#25846643)

Yes. This 95% is the mass everybody expected to see in plain old ordinary matter, but wasn't previously accounted for in the QCD theory. We already had the experimental observation; now, we just know that the the theory gives the same answer.

Essentially, it's not telling us anything we didn't already know, so we don't get any new theories out of it. It does increase the confidence in the existing theory, so people who are trying to figure out what the dark matter is can rely more strongly on the theories we already have. But it's not opening up any new avenues.

It's always a little too bad when theory and observation do mesh, because it's when they disagree that we really learn something. But it's also nice to know that the theories are good ones, so at least we can use them as a basis for seeking out other discrepancies.

Re:Ah, so THERE'S the dark matter everyone looks f (0)

Anonymous Coward | more than 4 years ago | (#25847081)

With a good theory it should say something like 'if it is correct you will observe X and not Y and not Z' for a REALLY good theory it will also say something like 'if it is wrong you will not see X but maybe Y and/or Z, and we dont understand Y and Z yet'

Without a good test it is just a theory. A good test should have positive tests and negative tests.

Take 'global warmming' both sides have a lot of theory but very little in the way of good tests that can prove it one way or the other. Then you dig into either side and it is a mish mash of bad science. We barely understand weather more than a day or two out how can we say if it is real one way or the other? That is bad science on both sides.

Re:Ah, so THERE'S the dark matter everyone looks f (4, Informative)

Ambitwistor (1041236) | more than 4 years ago | (#25847251)

Take 'global warmming' both sides have a lot of theory but very little in the way of good tests that can prove it one way or the other.

You can test it by observing that natural sources of warming don't agree with the magnitude, rate, or timing of the observed warming; and that human sources do. You can further observe, for instance, that an enhanced greenhouse effect will lead to stratospheric cooling as a result of heat being trapped lower in the troposphere, and we do observe that. There are further predictions which distinguish manmade warming from various types of natural warming, depending on the type of natural warming. For instance, warming from the atmosphere means the oceans warm from the top down, which is observed, and disagrees with theories that have the surface heat come from the oceans. The greenhouse effect also means that you get shifts in the diurnal and seasonal patterns of warming which disagree with the shifts predicted by solar-induced warming, because of the daily/seasonal patterns in sunlight shifts which do not occur for the greenhouse effect. And so on.

Photons (1, Interesting)

Anonymous Coward | more than 4 years ago | (#25846569)

Could someone please explain to me why photons don't have mass but do have energy (Photons [wikipedia.org] )?

Re:Photons (0)

Anonymous Coward | more than 4 years ago | (#25846735)

a photon travels at the speed of light (c), so its rest mass (zero) is divided by sqrt(1 - v^2/c^2) (also zero) to result in a non-zero effective mass.

Re:Photons (3, Informative)

elashish14 (1302231) | more than 4 years ago | (#25846863)

From what I've been reading, it appears that there are two kinds of mass - intrinsic and relativistic. In the case of photons, they have zero intrinsic mass in the same way that the quarks have only 5% intrinsic mass of the proton. However, their relativistic mass is derived from their energy (E/c^2), analogous to the remainder of the mass that makes up the proton as described in the article. I'm no expert, but that's what it sounds like.

Re:Photons (1)

metalman (33387) | more than 4 years ago | (#25847253)

So in this scenario, are they then combining the two types of mass to account for 100%? The type of mass that accounts for 95% of the particle is the energy given off from gluons and quarks, which is a relativistic mass since movements and interactions don't have intrinsic mass? But the intrinsic mass of quarks makes up 5%?

Or is saying that 95% of its mass "comes from the energy from the movements and interactions of quarks and gluons" just another way of saying there's other stuff in there that must have mass, we just haven't identified them yet? Aren't they confusing various definitions of mass to explain the total mass which they think should be there?

Re:Photons (1)

Ambitwistor (1041236) | more than 4 years ago | (#25847337)

So in this scenario, are they then combining the two types of mass to account for 100%? The type of mass that accounts for 95% of the particle is the energy given off from gluons and quarks, which is a relativistic mass since movements and interactions don't have intrinsic mass? But the intrinsic mass of quarks makes up 5%?

Yeah, that's basically it.

Aren't they confusing various definitions of mass to explain the total mass which they think should be there?

The conserved quantity is relativistic mass. The relativistic mass of the quarks, plus the relativistic mass of the gluons, equals the relativistic mass of the proton.

This is somewhat confused by the fact that relativistic and intrinsic mass of a particle are the same at rest. So if the quarks aren't moving too much, you can basically equate their relativistic mass with their rest mass. I'm not sure which is the 5% they refer to. And then, if the proton is at rest, then the relativistic mass which all the constituents add up to becomes the proton's "intrinsic" mass, treating it as a single particle.

Re:Photons (1)

Ambitwistor (1041236) | more than 4 years ago | (#25847283)

You're right. The "intrinsic" mass is usually called "invariant" mass or sometimes "rest mass" (although the latter doesn't apply to photons). The "relativistic mass" is called "relativistic mass", or "total mass-energy".

Poor headline (2, Informative)

Ancient_Hacker (751168) | more than 4 years ago | (#25846597)

This does not prove anything about E=mc2. You can't "prove" fundamental equations by twiddling bits.

They ASSUME that E=mc2, then use that equation to calculate the details of nuclear energies.

Grammar Problem or Misunderstanding? (1)

Timoleon (1225804) | more than 4 years ago | (#25846615)

In the article: "According to the conventional model of particle physics, protons and neutrons comprise smaller particles known as quarks, which in turn are bound by gluons." Shouldn't it read: "are comprised of"?

Higgs Boson? (2, Interesting)

MozeeToby (1163751) | more than 4 years ago | (#25846717)

I could be totally wrong, but I was under the impression that all the 'missing mass' of subatomic particle was believed to be generated by the Higgs Boson/Field.

Re:Higgs Boson? (2, Informative)

ceoyoyo (59147) | more than 4 years ago | (#25847239)

The mass of fundamental particles, like quarks and electrons, yes. Hadrons are not fundamental, they're made up of quarks and gluons, some of which are real and some of which are virtual. Most of the mass of the composite particle actually comes from the virtual components, NOT the real ones.

Albert Einstein: (0)

Anonymous Coward | more than 4 years ago | (#25846869)

I TOLD YOU SO! Just kidding. Keep up the good work!

Its NOT E=mc^2 (4, Insightful)

Lawrence_Bird (67278) | more than 4 years ago | (#25846945)

the correct statement is: E^2=m^2c^4 + p^2c^2

Re:Its NOT E=mc^2 (4, Informative)

DirePickle (796986) | more than 4 years ago | (#25847121)

I think that it's generally accepted that in that equation m is the relativistic mass.

Incomplete Equation (0, Redundant)

Tawnos (1030370) | more than 4 years ago | (#25846955)

I thought the full equation was
E^2 = (mc^2)^2 + (pc)^2

Re:Incomplete Equation (2, Funny)

Muad'Dave (255648) | more than 4 years ago | (#25847195)

E^2 = (mc^2)^2 + (pc)^2

Political Correctness has found it's way into Physics now, I guess.

After all these years... (1)

Paronomasiac (810476) | more than 4 years ago | (#25847013)

It's about friggen' time.

Step One Completed (0, Offtopic)

LifesABeach (234436) | more than 4 years ago | (#25847031)

Now for step 2? Resolving FTL Travel, Anti Gravity; and my personal favorite, Access to better Servers when I play WOW?

completely bogus interpretation (4, Interesting)

bcrowell (177657) | more than 4 years ago | (#25847051)

The article at theage.com gives a completely bogus interpretation, which is repeated in the slashdot article. The New Scientist article is much better.

It's taken more than a century, but Einstein's celebrated formula e=mc2 has finally been corroborated,

This is just total scientific illiteracy. E=mc2 has been verified over and over again. We see it, for example, in processes like alpha decay, where the sum of the masses of the product nuclei doesn't equal the mass of the original nucleus. Mass is converted into energy in that process, and that's been experimentally established since probably the 1920's. Likewise energy can be converted into mass, as when cosmic rays hit the atmosphere and create electron-antielectron pairs. The theoretical foundations of E=mc2 are also extremely firm; it's deeply linked to the basic logical structure of relativity, and relativity has been abundantly experimentally verified.

Saying that this calculation verified E=mc2 is just stupid. The calculation assumes (1) special relativity, (2) quantum mechanics, (3) some technical stuff about how to make special relativity and quantum mechanics work together (generic ideas about quantum field theory), and (4) a bunch of very specific technical approximations needed in order to get an answer out of this particular flavor of quantum field theory (lattice QCD). The calculation has a bunch of adjustable parameters (quark masses, coupling constants). You play with the adjustable parameters and get a bunch of numbers out (neutron and proton masses, etc). If the number of adjustable parameters that goes in is m, and the number of experimentally testable numbers that pop out is n, then n-m is the number of degrees of freedom that verify whether the calculation is right. (For n=m, it would just be a complicated exercise in fitting the data, like putting two points on a graph and saying "look, it's a line!") I assume they calculated more than just the mass of the proton and neutron, because otherwise n=2 would be less than m. I assume the n-m degrees of freedom checked out fairly well, because they're calling it a success.

To see why this calculation can't really be interpreted as a test of E=mc2, you have to imagine what would have happened if it had turned out wrong. If it had disagreed with experiment, then we would conclude that some of the assumptions built into it were wrong. Let's look back at the assumptions 1-4 above. Well, 1 (special relativity) has been verified a zillion different ways since 1905 (or even as far back as the 19th century, the Michelson-Morley experiment, with hindsight). 2 (quantum mechanics) has likewise been verified a zillion different ways since the 1920's. 3, the general framework of quantum field theory, has some ugly spots, but it's been used to verify things like the magnetic moment of the electron to a dozen decimal places, so it's still on fairly firm ground. 4 is extremely shaky; it's only very recently that anyone has claimed to be able to calculate anything at all useful and realistic with QCD. So if it had failed, no physicist in the world would have interpreted it as evidence that assumption 1 (relativity) was wrong. They would have interpreted it as evidence that assumption 4 was wrong: the lattice QCD approximations weren't good enough, probably for very boring, technical reasons that would only be of interest to a specialist in lattice QCD.

Wasn't he... (1)

Muad'Dave (255648) | more than 4 years ago | (#25847069)

...led by Laurent Lellouch...

Wasn't he the pitcher in "Bull Durham" [imdb.com] that hooked up with Susan Sarandon?

Oh wait, that was Ebby Calvin 'Nuke' LaLoosh; nevermind!

Funny. This Java script doesn't need supercomputer (3, Interesting)

Zdzicho00 (912806) | more than 4 years ago | (#25847103)

Use Heim Mass Calculator [daimi.au.dk] to easily compute masses of proton, neutron, electron and a lot of other particles as well, with a great precision (relative errors less then 0.00001) when comparing with most precise laboratory measurements available. The only hardware you need is Java in your browser.

This algorithm is based on 50-year old equations of Burkhard Heim thanks to his beautiful theory [wikipedia.org] . Notice that it include computation of neutrino mass which was found in recent years. When Heim was working on his theory almost all scientist were sure that neutrino is massless. The only input which this algorithm needs is a bunch of well known constants: h (Planck's Constant), G (Gravitational constant), vacuum permittivity and vacuum permeability.

Our current "mainstream" (hate this word) theory known as Standard Model is full of inconsistencies which are forcing scientists to constantly mumble about "dark mass" and "dark energy" stuff.
It remembers me about Enrico Fermi's comment "Beautiful theory, wrong universe". Does it apply here?

/Z

And the Answer is... (1)

strikeleader (937501) | more than 4 years ago | (#25847147)

42

needs to be repeated (1)

TheSHAD0W (258774) | more than 4 years ago | (#25847241)

What if these guys actually discovered a glitch in the theory, a mode where the amount of energy out exceeded the amount going in, tantamount to a free energy source - and then falsified the result in order to use the glitch for profit? "Nothing here, everything's consistent, now go away."

Conspiracy theory rules. ;-)

We're here! Virtually! (1)

tkjtkj (577219) | more than 4 years ago | (#25847321)

[/q]The Higgs field creates mass out of the quantum vacuum too, in the form of virtual Higgs bosons. So if the LHC confirms that the Higgs exists, it will mean all reality is virtual. http://www.newscientist.com/article/dn16095-its-confirmed-matter-is-merely-vacuum-fluctuations.html [newscientist.com] Good to know that my pain isnt real!
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