X-rays From Other Galaxies Could Emanate From Particles of Dark Matter

sciencehabit writes "X-rays of a specific wavelength emanating from the hearts of nearby galaxies and galaxy clusters could be signs of particles of dark matter decaying in space, two independent teams of astronomers report (first study, second study). If that interpretation is correct, then dark matter could consist of strange particles called sterile neutrinos that weigh about 1/100 as much as an electron."

Comments

That's "strange weird" not "strange flavor"

[jfengel]

It took me a second to figure that out. Neutrinos don't participate in the strong force and don't have any flavor. (The names are charming, but kind of annoyingly ambiguous out of context.)

They sure are strange-weird if they don't even participate in the weak force, as other neutrinos do. They're barely there at all (if they ARE there at all).

Re:That's "strange weird" not "strange flavor"

[gIobaljustin]

That might be the case, but it might also not be the case.

Re:That's "strange weird" not "strange flavor"

[Jane Q. Public]

"It took me a second to figure that out. Neutrinos don't participate in the strong force and don't have any flavor. (The names are charming, but kind of annoyingly ambiguous out of context.)"

Be careful when you say "charm" in the context of subatomic particles. (Or "strange", for that matter. I'm looking at you, OP.) You might end up saying something you did not intend.

I don't think they've named anything "weird" yet though. Still waiting for that one.

Re:That's "strange weird" not "strange flavor"

[marcosdumay]

I can't wait until the entire English vocabulary has a different meaning in subatomic physics. Things were better when the names were made-up.

Well, now on topic, we'd expect that any dark matter candidate is barely there at all, wouldn't we? The only problem (for me, certainly, no the theory) is that I don't understand how something with only 7kEv * c^2 of mass won't be seen already. Even if it shares no property with normal matter, I'd expect it to appear from bare energy + momentum available at accelerators*... Or are people just classifying them as normal neutrinos?

* I mean, would it be 10^-29 times as probable as a normal neutrino? Even if so, wouldn't people have seen a bunch of them?

Re:That's "strange weird" not "strange flavor"

[gregstumph]

*whoosh*

Re:That's "strange weird" not "strange flavor"

[Anonymous Coward]

I don't understand how something with only 7kEv * c^2 of mass won't be seen already. Even if it shares no property with normal matter, I'd expect it to appear from bare energy + momentum available at accelerators*... Or are people just classifying them as normal neutrinos?

Sterile neutrinos lack the weak interaction of normal neutrinos. The process that allows accelerators and nuclear processes to produce normal neutrinos is through the weak force. In the same way you can't take a photon and turn it directly into a neutrino + anti-neutrino because they don't interact with electromagnetism, you can't take "bare energy and momentum" to produce sterile neutrinos easily in accelerators. More subtle approaches look for them in accelerators, but having a light mass means you need quite a bit of precision to account for missing energy, and a situation distinguishable from say a normal neutrino. Search attempts also involve looking at neutrino oscillations closely, because of various models allowing mixing between normal and sterile neutrinos that could cause them to come up or affect neutrinos emitted from processes that can't emit a sterile neutrino directly.

Re:That's "strange weird" not "strange flavor"

[Anonymous Coward]

Neutrinos don't participate in the strong force and don't have any flavor.

Quarks have both flavour, which defines what type they are, and colour, which defines how they interact with the strong force. Quark flavours are up, down, top, bottom, charm and strange; quark colours are red, green and blue.

Neutrinos do not interact with the strong force, so they don't have colour. But they do come in different varieties, which are (as for quarks) called flavours. The neutrino flavours are electron, muon and tau, corresponding to the type of charged lepton they're associated with. (For example, when you destroy an electron, you have to produce an electron-flavoured neutrino.)

So, you're partly right - neutrinos don't interact with the strong force, but they *do* have flavour.

Re:That's "strange weird" not "strange flavor"

[Ferrofluid]

Why do you keep posting that?

Re:That's "strange weird" not "strange flavor"

[Anonymous Coward]

He thinks the Catholic church is conspiring to keep the truth from the world.

Re:That's "strange weird" not "strange flavor"

[jfengel]

(I was hoping somebody would notice. Thank you!)

Interesting Stuff

[rmdingler]

The data they're sorting through is only a 1% bump above the continuum,

but before the shouting about statistical noise begins,

RTFA... it sounds plausible.

Re:Interesting Stuff

[turkeydance]

could be signs......dark matter could consist..... Denver could beat Seattle......

Re:Interesting Stuff

[rmdingler]

Denver could beat Seattle......

The Meadows had forecast that very probability prior to the contest.

Re:Interesting Stuff

[93 Escort Wagon]

Well, if you're referring to the Denver Broncos playing football against the Seattle Mariners, then yes it's a possibility.

Otherwise no.

Re: Interesting Stuff

[s.petry]

Most science fiction sounds plausible, that is why we enjoy it. We have no proof dark matter or dark energy exists, so claiming side effects is pretty stupid. Sure, it is possible but it is equally not possie. A whole segment of theoretical physicists has been working on equations that don't require dark matter or energy with promising results so far.

Re: Interesting Stuff

[Baloroth]

Most science fiction sounds plausible, that is why we enjoy it. We have no proof dark matter or dark energy exists, so claiming side effects is pretty stupid. Sure, it is possible but it is equally not possie. A whole segment of theoretical physicists has been working on equations that don't require dark matter or energy with promising results so far.

And just as fast as those physicists have come up with those equations, they have been ruled out. Currently, none of the equations explain the phenomenon better than dark matter (and they're often much much worse). It's not equally as possible that dark matter exists as that it doesn't: the current evidence points to dark matter being more likely to exist than not. Tweaking equations and throwing in correction terms to force the model to fit the observations is usually a bad approach in physics (or science in general).

BTW, looking for side-effects that would result if dark matter does exist is, far from being stupid, a decent method of indirectly confirming the existence of dark matter in the first place (since observing dark matter directly is really, really hard, perhaps even impossible).

Re: Interesting Stuff

[rmdingler]

Sure, it is possible but it is equally not possie.

Probably, less than equally possible.

Nonetheless, these poor bastards are postulating intelligently with scant additional evidence about a theory yet to be empirically proven.

If they lack a quality necessary for scientific breakthrough, it is not imagination.

Re:Interesting Stuff

[mbone]

RTFA... it sounds plausible.

It may sound plausible, but it doesn't look plausible, at least to me.

Re: Interesting Stuff

[Anonymous Coward]

scant additional evidence about a theory yet to be empirically proven. ... If they lack a quality necessary for scientific breakthrough,

Well, you don't get scientific breakthroughs or theories to have more empirical evidence by not making quantitative predictions and comparing those predictions to observations...

Re: Interesting Stuff

[Vitriol Angst]

Of course equations work better with "dark matter" -- whatever is not calculable or not explained -- it's fricken' Dark Matter. You can't see it or sense it, but it is there, wherever observation and theory don't meet up.

Now, it might be there is such a thing as Turbulence due to Gravity, or sub-quantum fluctuations in the aether. Or even that Higgs Boson, shadows from another dimension or graviton flocking. Whatever it really is -- it will be called Dark Matter, so that everyone can feel like they understood what is going on.

Dark Matter is the best invention since the algebraic Variable. We could have called it substance X, but the Power Puff girls already had the copyright.

Re: Interesting Stuff

[s.petry]

This is supposed to be "Science" correct? Well it's not science at this level, it's science fiction. Is it plausible and possible that there is dark energy and matter? Of course, but we have no proof. Is it equally possible that we find some other missing thing proving that there is no dark anything, and our equations were never wrong.

My point was, and is, no theory of dark anything works either. Various physicists use various numbers for both dark matter and dark energy to make models work. That is not evidence that either exist.

To make a parallel, I could write up a great story of fluctuations in gravity due to dense matter. That is another plausible piece of physics which I find interesting to contemplate. We have no proof that there is such a thing, so me claiming that X happens because of dense matter would be equally unscientific.

Re: Interesting Stuff

[Anonymous Coward]

i look at it in 2 ways

if we ever figure it all out and there isnt "another layer of the onion lying beneath our latest discovery"life sure would be boring

and forget the sci fi author but there was a short story or small book where once the experimental subjects (thats us) become aware of the experiment the researchers end the experiment because it skews the experiment's results (we get offed by the more advanced researchers

so Im divided on this kind of thing

only want it to advance so we can finally leave this world and venture off into the stars

Why so many?

[Anonymous Coward]

Next question is why the universe would have an affinity to create so many? Seems highly doubtful to be the correct answer, but who knows...

Dark Matter Asteroids

[Anonymous Coward]

Really ?

I thought Dark Matter existed as asteroids ? :-)

(Just one of the amazing facts I learnt from watching a certain programme.)

Re:Dark Matter Asteroids

[mbone]

Really ?

I thought Dark Matter existed as asteroids ? :-)

In asteroids. (Maybe.)

Re:Dark Matter Asteroids

[davewoods]

I do believe OP is mentioning the "Good Shepherd" episode of ST:Voyager. I know it is the only thing I have been thinking about this whole time.

Starships

[symbolset]

That is pollution left by the warp drives. The k'Thref effect causes small portions of neutrinos to go irrational.

Re:Starships

[Soulskill]

It's mainly those jerks driving Sports-Utility Starships. Those things are dilithium guzzlers.

Re: Starships

[Anonymous Coward]

Why are you den

Re:Starships

[davewoods]

Let us not forget the tragedy of the Hekaras Corridor, go green!

Dark matter as likely as ether and phlogiston

[Anonymous Coward]

Given the repeatedly failed discoveries of exotic particles for "dark matter", it's as likely as "phlogiston", "ether", magnetic monopoles, and the Higgs bogon. It fills in some mathematical gaps that are better explained by better examining the real data. Stop inventing mystical forces to explain failures of measurement or because it makes equations symmetrical or petty.

The "experimental" reason to assume the prevalence of dark matter is confusing maps of distant galazies and their red shift. Simple errors of measurement or modeling of galactic density can explain the discrepancies. So can the recently discovered prevalence of "dark worlds", the startling number of planets that are *not* in orbit around a sun, only recently revealed by our best orbital telescopes and their occasional occulusion of other stars. Given such worlds widely spread across entire galaxies of interstellar space, galaxies could easily mass 20% more than expected from pure stellar mapping, which would handily explain most of the anomalies of galactic expansion.

So let's stop inventing funky physics that we don't need.

Re:Dark matter as likely as ether and phlogiston

[Anonymous Coward]

So can the recently discovered prevalence of "dark worlds", the startling number of planets that are *not* in orbit around a sun, only recently revealed by our best orbital telescopes and their occasional occulusion of other stars. Given such worlds widely spread across entire galaxies of interstellar space, galaxies could easily mass 20% more than expected from pure stellar mapping, which would handily explain most of the anomalies of galactic expansion.

Astronomers working on dark matter theories aren't ignoring that, and in fact were a big push for research into that starting over a decade ago. They expected to see a lot of occlusions to account for dark matter, but did not. The lack of and limited observations of such events sets a clear upper bound on how many such bodies can be in the galaxy and it is way below what is needed to explain rotation curves. The connections you draw to galactic densities and thinking 20% more observed baryonic mass is enough to explain situations suggests you don't really have any clue of the scale of the actual situations. Not only do you need to better examine real data, but you need to more than glance at the headlines as a start.

Re:Dark matter as likely as ether and phlogiston

[CHIT2ME]

There are two things you are forgetting in your critique. First, we are just beginning to look for occulusions caused by "dark worlds". It's far too early to draw any conclusions on this. Second, what about the billions or even trillions of small to medium black holes floating about the universe? These, also, cannot be seen and have a bad habit of curving light around themselves to further hide themselves from detection. As I hope you are aware, black holes, even small ones have enormously more mass than even Jupiter sized dark worlds.

big brass ones.

[meglon]

sterile neutrinos that weigh about 1/100 as much as an electron.

So what you're saying is, once you sterilize a neutrino, it only weighs 1/100 as much as when it still had balls. Those aren't just big brass ones, those are big brass ones armored in the stuff they armor Ogre's with.

Re:big brass ones.

[Anonymous Coward]

So what you're saying is, once you sterilize a neutrino, it only weighs 1/100 as much as when it still had balls.

No, the neutrino is lighter than the electron. I'm not sure how accurately the mass of the neutrino has been measured, but AFAIK a massless neutrino is within the margin of error. Though a massless neutrino might be conflicting with other theories, so it may be more likely the neutrino is not massless but just much lighter than anything else we have measured.

Re:big brass ones.

[Anonymous Coward]

There is a known mass difference between the three flavors of neutrinos, as the square of the mass difference is a lot easier to measure than absolute mass of them. Even if the lightest one was massless, that would suggest the other two are not massless, as zero difference in mass is about 10 sigmas away from the current estimates of the differences.

Three sigma?

[mbone]

If you believe Figure 5 in this paper, I have a bitcoin exchange I would like to sell you.

Re:Three sigma?

[mmell]

Three sigma. As in .001 probability that the null hypothesis is true despite our sample observation.

Not even significant enough to justify a paper. Enough to justify further experimentation, but not even nearly strong enough to even suggest a correlation yet.

That's the problem with real science - the paperwork's a bitch.

Re:Three sigma?

[Anonymous Coward]

Not even significant enough to justify a paper. Enough to justify further experimentation,

You seem to have things ass-backwards, since typically the criteria needed to justify further experimentation is higher than a paper, especially considering each experiment and observation in such fields gets used for as much as it can, and to make current results available so other scientists can give their input on new experiments. Depending on the exactly what you are doing, how much has previously been done on the subject, a paper can easily be justified with results less significant than one sigma to times when you want to wait for more than five. Usually two sigma is plenty to suggest a correlation, even if that is not enough to assume a correlation as solid fact.

Re:Three sigma?

[sFurbo]

Three sigma. As in .001 probability that the null hypothesis is true despite our sample observation.

No, 0.001 probability that we would observe this, or worse, if the zero hypothesis were true. In order for it to tell anything about the probability of the null hypothesis being true, you need to include the probability of the null hypothesis being true before we made the observation.

Re:Three sigma?

[ceoyoyo]

Whoever came up with that explanation for a p-value was undoubtedly well meaning but should have been gagged. It confuses more people.

The OPs definition is simpler, much more intuitive, and correct if you add "given only the data collected in the experiment." You can actually make an argument that the OPs definition is correct as is since "null hypothesis" refers to the statistical hypothesis, which is generally assumed to relate only to the current experiment.

Yes, you can't make judgements about the actual probability without priors, but friends don't force their informative priors on friends.

Re:Three sigma?

[Anonymous Coward]

Simpler but completely incorrect. In order to say something about the probability of the hypothesis being true you have to work in Bayesian statistics. Frequentist statistics only assign probabilities to the outcome of repeated trial hence the "probability that we would observe this, or worse, if the zero hypothesis were true" is referring to the probability of obtaining a particular (or one of a particular set) observation from repeated trials given that the hypothesis is true. There is no meaning to the phrase "probability that the hypothesis is true" in a frequentist frame work since the hypothesis is not a randomly distributed variable it's either true or it isn't.

Re:Three sigma?

[sFurbo]

As the AC said, you are interpreting the frequentistic concept of p-value in a Bayesian framework. I think it says something about frequentistic probability theory that its most famous concept is confusing except if it is explained in an incompatible framework.

Could?

[Anonymous Coward]

"Could" this and "could" that.

Wake us when there's absolute proof.

Re:Could?

[mmell]

Sleep, little anonymous one. Sleep forever . . .

Re: Considering Republicans...

[John Da' Baddest]

And this relates to dark matter how?

why does the interface keep changing here?

[Anonymous Coward]

What is going on on slashdot? What is with the gray text on gray background? This is annoying, black text on white is easy to read, screw "pretty", make it useful! STOP SENDING ME TO THIS MESSED UP INTERFACE!

Re:why does the interface keep changing here?

[mmell]

If you don't like it, why do you keep coming here?

Re:why does the interface keep changing here?

[RandomFactor]

That's only peripherally related - Dark Pixels. Very difficult to see.

There is no dark matter

[flyingfsck]

There is no dark matter. The weight of the visible galaxies were estimated wrong.

Re:There is no dark matter

[Anonymous Coward]

Came here to say this.

Re:There is no dark matter

[mmell]

Thank you! Please stop inventing luminiferous aethers unless you can come up with something like evidence that one exists. Unexplained phenomena (e.g., "cosmic expansion") are not evidence.

Re:There is no dark matter

[Anonymous Coward]

Yeah, I'm still waiting for evidence that neutrinos even exist, instead of unexplained phenomena like missing momentum, energy, and cross-Earth correlations between nuclear reactors and detectors.

Re:There is no dark matter

[Bengie]

And the gravitational lensing the in the galactic voids is just magic. Fully transparent voids that are 10x-100x larger than the Milkyway, with no observable matter, not even dust, yet huge amounts of detectable gravity via lensing back-ground galaxies.

Re:There is no dark matter

[ceoyoyo]

You realize our current accepted theories of quantum mechanics have the luminiferous aether in spades, right? It's called the electron field, which permeates the entire universe and has "electrons" as energetic disturbances within it. It's joined by many other aethers, I mean fields, such as the family of quark fields, the neutrino fields and the Higgs field(s).

It's hilarious when Slashdot armchair science critics use that example.

Re:There is no dark matter

[Anonymous Coward]

Or just plain, old electric and magnetic fields that permeate out to infinity in a real world without perfect conductors. The armchair crowd seems to have redefined the luminiferous ether from what it was in the past (which is impressive considering how vague and changing its definition was then) to mean anything that permeates space, then act like dark matter or dark energy is the only example of that in science.

Re:There is no dark matter

[mmell]

So you're answer is "You're wrong - this highly theoretical, unverified, counter-intuitive solution which relies upon an unknown and undetectable quantity is right, 'cuz we all think so".

Yes, these theories explain the observed phenomena - but so does "G*d did it!". Theories are great - but a little more suporting evidence would be in order, I think.

Looks like a simple explanation is needed

[dbIII]

Dark matter just means stuff we know is there from gravity effects but can't actually see.
It's like having someone step on your foot in a dark room - you know somebody or something else is in there but you only know from one limited sense.

As for phlogiston - damn good idea to explain some reactions if you don't know there is more than one type of gas and it was associated with some useful empirical equations. Oxidation of iron didn't fit. Not long after oxygen was discovered. Phlogiston was science in action - put up an idea - test it - find where it doesn't work and then you can find another fit.

the startling number of planets that are *not* in orbit around a sun

Nowhere near the same thing. We can see those with light and radio waves from the stuff behind them.

Re:Looks like a simple explanation is needed

[Anonymous Coward]

> Dark matter just means stuff we know is there from gravity effects but can't actually see

Unfortunately, the phrase has been co-opted to cover exotic matter, and some serious wild goose chases have been run to try to invent exotic matter. That's where it 's become like "the ether", with contradictory properties never seen united in nature..

> Nowhere near the same thing. We can see those with light and radio waves from the stuff behind them.

It's turned out to be extraordinarily difficult. They're distant, they're extremely small compared to the distances involved, and they are *cold*. Detecting occultation by objects that are not in orbit around stars and thus unlikely to occult again is like detecting leaves landing in a forest a mile away. Simple ede distortions of the shadow cast by such a planet in the light from suns, nebula, or distant galaxies will smear optical optical or radio images below the ability to resolve them. It's only relatively close such objects that we've been able to detect, and there seem to be a *lot* of them. We've only recently actually been able to measure enough of them to get some idea of their prevalence, and the amount of interstellar matter is pretty starting.

Re:Looks like a simple explanation is needed

[Anonymous Coward]

It's only relatively close such objects that we've been able to detect, and there seem to be a *lot* of them. We've only recently actually been able to measure enough of them to get some idea of their prevalence, and the amount of interstellar matter is pretty starting.

It is only a lot in the human scale sense, not a lot in the sense there is some huge amount of missing mass in the form of rogue planets. This was a big disappointment in some sense, that astronomers thought an easy solution to the galaxy rotation curve problem would be stuff we just have trouble seeing. except as hard as it should have been to see such things, we would need to see a lot more. Additionally, other problems in astronomy besides just galaxy rotation curves popped up and could all be explained by dark matter, leading to...

Unfortunately, the phrase has been co-opted to cover exotic matter, and some serious wild goose chases have been run to try to invent exotic matter. That's where it 's become like "the ether", with contradictory properties never seen united in nature..

Yes, because there is now evidence that missing regular matter is unable to explain various observations. Those same observations also show we are not seeing a lot of normal matter too, as in there is a lot of regular matter we are missing that is not part of "dark matter." It always seems odd how people are quick to talk of hubris of assuming astronomy has seen all there is to be seen (which astronomers know they have not...), but it is okay to assume there particle physicists have seen all of the particles there are to be seen.

Re:Looks like a simple explanation is needed

[Pino Grigio]

It's stuff you think is there because of gravitational effects assuming the laws of physics as currently understood hold at those larger scales.

Re:Looks like a simple explanation is needed

[Anonymous Coward]

> Additionally, other problems in astronomy besides just galaxy rotation curves popped up and could all be explained by dark matter, leading to...

Stellar and galactic astronomy, as wonderful and intriguing as it is, has very limited instrumentation dealing with very remote objects. The desire to invent new types of matter to explain interstellar behavior is a bad and confusing habit, a direct violation of Occam's Razor. Knowledge about spin, gravitational lensing, and galactic clumping is coming from better instruments and careful analysis of existing data, without inventions of exotic matter that has no direct experimental verificaton.

The hubris, I think, comes when s subtle discrepancy in an analysis of an analysis of an analysis is used to justify rewriting observable behavior of matter, rather than more reasonably checking the error bars on your original measurements. Hubble Shift calculations of distant galaxies, for example, make enormous assumptions of lack of obscuring material or the behavior of older stars to conclude the distance of those objects. The error bars are *enormous*, yet second and third and fifth order analyses of intergalactic expansion are made from these analysis..

It's like sampling a $5 bottle of table wine and deducing the climate of the village the grapes growers came from, and deducing that the wine growers were Pastafarians because of the lack of climactic shift compared to wine from *a different continent*. It's *silly*.

Re:Looks like a simple explanation is needed

[Anonymous Coward]

he desire to invent new types of matter to explain interstellar behavior is a bad and confusing habit, a direct violation of Occam's Razor

Funny how Occam's Razor is the greatest things ever to an armchair physicist when trying to argue current theories are too complicated or propose that they are just wrong. It always comes down to some horribly subjective definition or idea of what it means for something to be complex or unnecessary, a proxy ultimate for them just not liking something. How often do you see people who insist proposing a new particle is "obviously" ignoring Occam, while proposing their own new ideas like arbitrary terms to a new theory of gravity or "obscuring material" that acts differently from any other forms of obscuring material we've seen before. And yet at the end of the day, those that they claim to be flaunting this golden rule are making quantitative predictions while those arguing on the net can't do more than just grump about vague things, using Occam's Razor as a psuedo-intellectual form of "Nyuh uh, you're wrong, because." It is also funny how fast one loses count of the number of seminars and colloquia about dark matter alternatives that end with, "Well, it is a promising start, but still doesn't match observations as well as dark matter" when you work some place that has such researchers around frequently.

Re:Looks like a simple explanation is needed

[dbIII]

Unfortunately, the phrase has been co-opted to cover exotic matter

By who exactly? Journalists that never did anything other than the compulsory science in school and haven't been reporting for long or someone else?

they're extremely small compared to the distances involved

And are likely to be nothing than a blip considering the mass involved. You do know the amount that we're talking about here don't you? Not just 0.005 of the expected mass of what we can see but many orders of magnitude more. Surely you could pick up that much of an understanding even if you are limited to this site for your source of general knowlege.

Re:Looks like a simple explanation is needed

[dbIII]

That's the assumption we have to make until something shows otherwise.

Re:Looks like a simple explanation is needed

[Pino Grigio]

The funny thing about this comment is that if you rephrase "dark matter" to be "the error in our observations when compared to theoretical calculations", it's not really a surprise that dark matter matches it so well. Dark matter has been specifically hypothesised to fill in the discrepancy here, so OBVIOUSLY it's going to fit any theory that includes it extremely well. Indeed, it is parametrised to do so!

Re:Looks like a simple explanation is needed

[Anonymous Coward]

The interesting thing isn't that someone came up with a label for a difference between theory and observation, but that a proposed solution to the difference can explain several differences, and is far from overfitting. Whereas many alternatives end up being overfit models, for example having arbitrary additions to gravity that require fitting to solve one specific issue but needing different tuning to fit others.

Typo

[dbIII]

Not long after that oxygen was discovered

Phlogiston was a short-lived idea from before the discovery of oxygen. We don't know if it was taken seriously or was just a chemical shorthand to mark unusual reactions.

Oh, I can answer that.

[neoshroom]

He might be a bot, but he also might not be a bot.

wrong

[Anonymous Coward]

Dark matter is composed of chemically inert hydrinos.

I really hate to mention this, but ...

[mmell]

Has anybody noticed a trend among cosmologists and sub-atomic physicists to invent new, undetectable stuff (dark matter, dark energy) when they encounter phenomena they can't otherwise explain?

Yes, they (nuclear physicists) predicted the existence of and found a particle at around 1.27GEv. Might even be Higgs they said they were looking for. But they've outright defined dark matter and dark energy like Wilson's teapot - we can never see 'em directly, only their effects. Well, if these quantities can affect our physical universe, then there's a way for our universe to affect these quantities which means they do interact with normal matter and energy, and that means they should not be undetectable like Wilson's teapot.

Next thing you know, cosmologists will be telling us that G*D did it. I'm okay with that . . . but only if you come up with some kind of evidence, not merely "well, we can't find anything else to explain it...".

Re:I really hate to mention this, but ...

[Anonymous Coward]

Might even be Higgs they said they were looking for. But they've outright defined dark matter and dark energy like Wilson's teapot - we can never see 'em directly, only their effects. Well, if these quantities can affect our physical universe, then there's a way for our universe to affect these quantities which means they do interact with normal matter and energy, and that means they should not be undetectable like Wilson's teapot.

You say this in response to an article giving one example of precisely what the second half of the quote proposes... it is an example of astronomers looking for an effect of dark matter interacting with normal matter and energy. And this is one among many other already done and proposed observations for other such tests. Your issue may in part be that the first half of the quote is not how dark matter and dark energy are defined...

Re:I really hate to mention this, but ...

[mmell]

Giving credit while asking the question, is all. Yes, I understand that initially the Higgs Boson was nothing more than an intellectual fantasy, until proper experiments were devised with agreed-on criteria. A prediction was made and then supported.

Dark matter and dark energy (as I understand the ideas) both preclude this - the first thing I"ve learned about either of these two theoretical quantities is that they're defined as not interacting with normal matter and energy. At this point, we're talking about Wilson's Teapot here - except that even Wilson's Teapot will surrender someday to better observational techniques and better experiments which show that such a teapot is really pouring rain down on us (or not).

I don't mind the part where we're told we haven't detected it yet. I do mind the part where we're told they're undetectable, we can only see the secondary effects of their existence. That's exactly what ghost hunters keep telling the rest of us, and I really mislike the similarity there. If proponents of dark matter and dark energy theories would at least assert a testable prediction (even if it's not testable right now), it would help; but saying that it explains the observation correctly (gravitic lensing, cosmic expansion) is one hell of a long way from providing evidence that the theory is correct, or even meaningful.

Re:I really hate to mention this, but ...

[Anonymous Coward]

that they're defined as not interacting with normal matter and energy

No, this is flat out wrong. You've created a very flimsy strawman to knock down by using that definition. It should be pretty obvious that dark matter is not defined as being unable to interact with ordinary matter since the very reason the theory was created to explain effects seen in ordinary matter via an interaction. Plus the on going research looking for interactions of various types. Dark matter gets its name from have weak or no interaction with electromagnetism, but that is a long ways from saying it doesn't interact with normal matter. This is why searches have included things like looking for MACHOs, which would just be literally dark pieces of rock or black holes, to candidate particles that would interact with the strong and weak forces, or in this case sterile neutrinos which interact with other neutrinos. Plus all of those interact with normal matter through gravity.

Hey, wait a minute . . .

[mmell]

I know that we know better now, but weren't neutrinos supposed to be massless when their existence was first proposed?

Sterile Production

[Roger W Moore]

The only problem (for me, certainly, no the theory) is that I don't understand how something with only 7kEv * c^2 of mass won't be seen already.

Sterile neutrinos are usually thought of as being produced by mixing with normal neutrinos. Hence the coupling to matter is extremely weak and with such low masses it is quite easy to imagine that they would have escaped detection so far. However neutrinos are produced with velocities near the speed of light in the Big Bang whereas dark matter is slow moving (it's "Cold Dark Matter") so it seems unlikely unless there is some production mechanism which can produce them at a slower velocity. Also, not that it really makes much difference but technically these are gamma rays not x-rays. The energy ranges for both overlap and the name depends on how they are produced - in physics photons from particle decay or annihilation are gamma rays.

Re:Sterile Production

[Anonymous Coward]

The energy ranges for both overlap and the name depends on how they are produced - in physics photons from particle decay or annihilation are gamma rays.

Astronomers tend to just go by the energy in their definition, with typically 100 keV cutoff, because they traditionally were more concentrating on the detection of x-rays instead of production of x-rays.

Re:Sterile Production

[budgenator]

I pretty much understood the article, so obviously it was "dumbed" down to non-physicist levels so I wouldn't get to excited about the X-ray vs. Gamma ray mix-up, especially since the photons were about half the typical KVP of a dental X-ray.

So it's not dark energy or dark matter...

[mmell]

It's a neutrino that we've never detected. Okay, I'll bite. How do we detect/identify a sterile neutrino? For bonus points - we've been looking for neutrinos as a species for a little while now, if there is a way to detect and identify a sterile neutrino, why haven't we seen these yet? This kind of assertion requires more than three sigma confidence with noted exceptions. Just sayin'.

Dark Matter is really Gravity.

[Anonymous Coward]

Dark Matter is a fiction when in reality it is another form of gravity or rather a super coalesced form of gravity. What no one talks about is the speed of gravity and in that regard, Gravity permeates the entirety of the universe (visible and non-visible) and is instantaneous in all directions.