Physicists Build Donut-Shaped Magnet To Find 'Ghost-Like' Dark Matter Particle (cnet.com)

An anonymous reader quotes a report from CNET: One of the central puzzles in particle physics is discovering what particle (or particles!) makes up dark matter — the form of matter that is responsible for 85 percent of the mass in the known universe. Some physicists believe searching for a hypothetical particle known as an "axion" could lead to a better understanding of dark matter and to hunt for it, a team of U.S. physicists have recently designed and tested a basketball-sized, donut-shaped apparatus that can seek it out.

It has been believed that axions may be detectable by looking at an unusual type of neutron star known as a "magnetar". These small, erupting stars create some of the most powerful magnetic fields in the universe. Because of their giant magnetic power, axions would be converted to radio waves in the presence of the magnetar -- and thus, detectable by telescopes on Earth. That strange cosmic phenomenon inspired theoretical physicists to create the impressively-named ABRACADABRA experiment (the full name is "A Broadband/Resonant Approach to Cosmic Axion Detection with an Amplifying B-field Ring Apparatus" so the theorists deserve a round of applause for that backcronym). The experiment consists of a donut (or "toroid") shaped device, dangled in a freezer just above absolute zero and fine-tuned to create its own magnetic field. If axions exist, the magnetic field in the middle of the donut could reveal them. The study has been published in the journal Physical Review Letters.

Comments

Could it be?

[Mister Transistor]

The FARGate? Completely legally different than StarGate?

Re:Could it be?

[jfdavis668]

There's no way it came from that movie, or that syndicated series based on the movie.

"Dark" "Matter"

[Anonymous Coward]

It's responsible for 85% of the mass of the known Universe, but we can't seem to find any. Yes, you in the back? No, there's no way we're mistaken, next question?

Re: "Dark" "Matter"

[Anonymous Coward]

A Nobel Prize is up for grabs to anyone who can come up with a testable idea that does a quantitatively better job of reconciling theory and measurement. That's why some of the smartest people in the world are working on it. Why don't you step in and best them all?

Re: "Dark" "Matter"

[Anonymous Coward]

I don't need to know the answer to recognize hand waving and wishful thinking when I see it. I can produce an incorrect proof that P = NP, does that mean you can't criticize it if you don't have a valid proof to the contrary?

Re: "Dark" "Matter"

[jellomizer]

If your proof that P = NP is incorrect but not yet independently identified, or had found a fault. But your proof is more of a Postulate or a Theorem.

One can still criticize a proof even if they cannot produce a counter proof. Because your proof isn't the final outcome but the steps to get to that point.
I don't have you discredit your Poof of P = NP by proving that P != NP but by going threw the steps in your poof, finding the error in your logic, often making an assumption or muddying the proof with other methods such as "Proof by intimation" by often stating something like "It is now obvious to anyone with a half a brain that from point A we now lead to point C."

 

Re: "Dark" "Matter"

[ThePyro]

Don't be so quick to dismiss dark matter! We have good reasons to speculate about the existence of a particle which doesn't normally interact with electromagnetic fields. In the example above, huge clusters of galaxies collided with each other and the ordinary matter slowed down as a result of the collision, but gravitational lensing suggests that the center of mass (i.e. dark matter) got separated during the collision. It's not a slam dunk, but it's an interesting result that suggests there's more going on than just an incomplete model of gravity.

Re:"Dark" "Matter"

[Sarten-X]

Since this is Slashdot, I'll throw in a car analogy, in the time-honored tradition.

You can see my car, a good distance away on level ground. It seems to be moving away from you. With more observations, you can tell it's not just moving, but actually picking up speed.

Since the ground certainly seems level, and you don't see anything else around, it's a safe assumption that my car does indeed have an engine, and someone's driving it away from you.

Now, the problem is that engine doesn't actually create any power. It just transfers the energy from its fuel, so it's also a safe assumption that my car has a fuel tank (or batteries, if electric), and that's providing the energy for the acceleration.

Now back to dark matter...

Galaxies don't have engines or fuel tanks, but we've recently confirmed that they are actually accelerating... and far more than makes sense for the amount of mass and energy we've seen. To use another car analogy, it's like having a horse-drawn cart keeping up with a race car... It's enough to suggest something really fishy is going on.

When something fishy happens in astrophysics, it means either our formulas or our models are wrong. Since our formulas seem to be correct everywhere else, we've started looking for this "dark matter" stuff, under the suspicion that it might hold the energy we're looking for... like finding rockets hidden under the bottom of the horse-drawn cart.

It is still possible that our formulas are wrong... but to match other experiments' results, they'd have to be off by an extremely small amount in some cases, and extremely large amounts in other cases. That means not just a tweak to a scalar value somewhere, but restructuring equations entirely...and we'd still need some kind of reason for the discrepancy. Draft horses don't run at race car speeds, and if they did, they wouldn't look like draft horses.

Looking for dark matter and the dark energy it caries is actually the simpler solution. The theory fits well with our existing observations, and doesn't require completely overhauling our understanding of how the universe works. If we keep running experiments like the one in TFA and finding nothing, we'll start the huge undertaking to figure out what else might be happening, but for now this is the sensible approach.

Re: "Dark" "Matter"

[Anonymous Coward]

Can the claim that 85% of the universe is made of stuff we haven't yet isolated not be a valid criticism of the logic behind the dark matter hypothesis? Certainly if I claimed there were unicorns in my sock drawer turning them inside out, you would criticize the mental leap required to create the unicorns even if I could point to some socks that were inside out? "But the unicorn theory neatly explains the socks being turned inside out. Until you have a better theory you cannot criticize this." Sure.

Re: "Dark" "Matter"

[Anonymous Coward]

Yes, but, if there were also unicorn poop in the drawer I might have to take your theory seriously.

Re: "Dark" "Matter"

[Anonymous Coward]

We've discovered a bunch of particles in the past 50 years, why is it wishful thinking to assume that there might be more?

Re: "Dark" "Matter"

[jellomizer]

Dark Matter hasn't been proven yet. However its hypothesized nature does fit into the mathematical models of the trended data of the observed universe.
Right now with our understanding of gravity and the universe expansion it would seem that we need more mass then what is observable. Could it be something different, yes. But the point of this article, is try to find ways to detect this "Dark Matter" where we then can either show that it does exist and now it is observable (no longer being dark matter) we can study it further and see if its properties does indeed help fill out all the number to match our models.

If we see that n^2 = 9 n will be equal to 3 or -3, both fit the model. However chances are it will be 3 not -3 as positive values are more common then negative ones.
This isn't good enough to pass a math test, however if we are going to make a model of the universe, we should pick the more common and simplest answer then trying to explain the more complex model.

Re:"Dark" "Matter"

[Anonymous Coward]

How on Earth is this idiotic response marked Insightful????

Re:"Dark" "Matter"

[greythax]

There are billions of WHOLE PLANETS we can not directly "see" yet, and you have a problem with the idea that there might be some widely diffuse clouds of exotic matter that we can't identify? Wow, you have a lot of faith in telescopes without much in the people who made those telescopes.....

Re: "Dark" "Matter"

[Anonymous Coward]

Dark Matter hasn't been proven yet. However its hypothesized nature does fit into the mathematical models of the trended data of the observed universe.

But this is no surprise because the nature of Dark Matter are made to fit into the mathematical models. Dark Matter is "invented" to fill the gaps.

Re: "Dark" "Matter"

[Anonymous Coward]

In the absence of unicorn poop, we can safely assume that unicorns don't poop. See what I did there?

Re:"Dark" "Matter"

[UnknowingFool]

I don’t know the finer details of dark matter, but what I do know is that one of the very first questions posed about the existence of dark matter was whether it was just unaccounted ordinary matter. And further research said no it was not. And it wasn’t one team/person that verified this. Multiple teams in at least two ways have verified the numbers.

Also using visible light isn’t the only technique cosmologists use. The EM spectrum consists of way more than human visible light.

Re:"Dark" "Matter"

[Anonymous Coward]

You might counter that, OK, we could call it DOGFOOD instead of dark matter, but the current consensus is that DOGFOOD is some kind of particle. Alright, great. Then where is the evidence that it's a particle? Normal particles are great because you can smear a bunch of them in a petri dish and look at them under a microscope. Quantum physics aside, particles are definite things that definitely exist in definite places. Is dark matter comprised of particles in the same sense? If so, show me the petri dish. If not, why call whatever DOGFOOD is made of particles?

OK, if you feel it's a bad name then fine. I have no particular dog in that race.
In fact you have at least one if not two generations of people behind you on that one, not wanting to use the word "dark" to reference something unknown.

As for it being matter, this comes out of the Friedmann equations.
"Matter" is something with an energy density that scales to the inverse cube (^ -3) of the universes scale factor.
"Radiation" is the other option, which has an energy density that scales to the inverse forth power(^ -4) of the scale factor.

The observations wouldn't exist if dark matter was only to the inverse power of -4, and we do observe it obeying scaling to the inverse cube.
It also can't have the same density everywhere in space, since then it wouldn't interact with itself, and all observations show that it does. We also see this in the CMB, and we see it from gravitational lensing effects around galaxies.

Short version, radiation wouldn't cause the observations, matter would. There aren't any other options to pick from.
It also started out uniform and later clumped together, a property shared by 100% of all matter we see, from planets to stars to galaxies to filaments.

As for if it is a *particle*, that only stems from the fact all of the matter we know is in the form of a particle, and we don't know if any matter that isn't a particle.
Short version again, if it isn't a particle, what would it be? There are no other options we know of to pick from.

I mean, we aren't even very sure about what gravity actually is at this point.
Most think it should be a particle (graviton) but some think it is an attribute of the universe being manifested and not within it at all.
If it turns out gravity isn't a particle, not to put words in anyones mouth, but I'd guess you would see nearly everyone more than willing to 'jump ship' and change the default assumption of what dark matter could be to that.

But so far the universe has consistently behaved quantized when dealing with matter, and so would anything causing the dark matter effects we see. Like I said it's a default assumption and is for a very good number of reasons.

It is far more logical to start going down the list of things we know are possible and rule them out before we start day dreaming about what has so far shown consistently to not be possible.

Why start trying to rule out non-existent items on a non-existent list? When we have a perfectly good list of things that do exist to rule out from.

Re:"Dark" "Matter"

[swillden]

and doesn't require completely overhauling our understanding of how the universe works.

If I were to bet on precisely where we are getting this question wrong, this would be where I threw my money.

The problem with this view is that it's completely unproductive. Okay, so you start by throwing out everything from Newton onwards? What do you replace it with? Something different, sure, but where do you even start to figure out what the shape of that replacement is? And in the meantime how do you calculate rocket trajectories, etc.? Well, obviously you have to continue using what you threw out, so you didn't actually throw it out, did you?

No, the best bet is to continue using what we have that appears to work in all of the other cases and trying to fill in the holes. Maybe the effort to find dark matter and dark energy to explain the discrepancies won't work, but even if it doesn't, maybe the search will show us something else that begins to give us a clue about how to fix the models.

Re: "Dark" "Matter"

[Darinbob]

But the idea that there is 85% of the universe that we can't detect comes from measurements that strongly hint that this may be true. We can't detect the unicorn but we can see the unicorn poop in your sock drawer. Alternate theories may be true if they can also explain the missing mass or the appearance of rainbow poop.

Re: "Dark" "Matter"

[Darinbob]

The theories point to there being something missing out there, and some form of matter that we can't yet detect is one idea that people are trying to test. Other idea may be true instead. However just rejecting the whole concept and claiming that what we currently know is the entirety of what there is means we have to rewind many decades of physics.

Re: "Dark" "Matter"

[Darinbob]

125 years ago we couldn't detect electrons and they were only a theory. 51 years ago we hadn't detected any quarks and only theorized about their existence. So why today does it make sense for a lay person to put down their foot and say "it's nonsense!" when they hear about some other form of matter that we can't detect?

Slightly apropos, the word "quark" in German is slang for "rubbish" or nonsense.

Re:"Dark" "Matter"

[thereddaikon]

Dark Matter is merely the name given to the observation. It's not a theory stating that the universe is full of black stuff that's hard to see. There are many competing ideas on what exactly dark matter is. The possibility that we just have got gravity wrong again is one of them. Once we can account for the observations then it will no longer be called dark matter. It will be called something more appropriate.

This is something that layman reporting on physics often does a poor job of explaining. It's often presented as Dark Matter is a specific thing and scientists have been spending years trying to find data to prove it. That's bad science and not at all how it works. The reality is, dark matter and dark energy are just placeholder terms for observed behavior of the universe and there are many possible causes for those observations. They've been spending the last 30 years going down the list and crossing the possibilities off with clever new experiments and ever better observations.

Re: "Dark" "Matter"

[Bengie]

Theories pointing to something missing is much less interesting than observations objectively showing that something is missing, which is what the Dark Matter phenomena is.

Re: "Dark" "Matter"

[Bengie]

It's not missing mass. We think it's missing matter because it's the only thing not moving at the speed of light that could explain the observed mass which has no corresponding matter.

Re: "Dark" "Matter"

[Pfhorrest]

Slightly apropos, the word "quark" in German is slang for "rubbish" or nonsense.

Any connection to "quark cheese" scraps? (Like maybe those bits of cheese were considered "rubbish", discardable?)

Re:"Dark" "Matter"

[Pfhorrest]

It sounds like you are talking about dark energy rather than dark matter. Dark energy is whatever it is that is accelerating the expansion of the galaxies away from each other. Dark matter is whatever is keeping galaxies gravitationally bound into themselves given the rates that we observe them spinning (at which rates the mass accounted for by visible matter would not be enough to keep all the stars in them from flying apart into intergalactic space).

Re: "Dark" "Matter"

[Darinbob]

Equations are pointing to something missing. No one just made this shit up.

Donut shaped?

[140Mandak262Jamuna]

We were freshman in IIT, having passed JEE, head high in the clouds, top 1000 All India Rank, all the orientation speakers calling us creme-de-la-creme of India. First Chemistry 101 class. Reading ahead for the class, our study group found there are some electron orbital stuff, n orbital, p orbital etc. One of them was described to be doughnut shaped. All of us were stumped. We did not know what a doughnut was or what it would look like.

Then one from our study group found an American chemistry text book with pictures. It spelled doughnut as donut, but had a picture. We exclaimed, "It is a damned torus! Why wouldn't they call it a torus? Why use this weird thing donut/doughnut". In the class Prof PJ Narayanan said, "... it says doughnut in the text book. Doughnut is like a vada but it is sweet not savoury, they make in the West..."

If slashdot is going to call itself "news for the nerds" the least it can do is to call that shape by its proper name, a torus.

Re:Donut shaped?

[Kokuyo]

Is it really that important in which foreign language the thing is described? At least the English language isn't dead, no matter how much it gets tortured by each new generation ;).

Re:Donut shaped?

[140Mandak262Jamuna]

Torus is an English word. It has origins in Latin. But it is a very legitimate English word.

Re:Donut shaped?

[Anonymous Coward]

Well this discussion just went pear shaped

Re:Donut shaped?

[140Mandak262Jamuna]

It is street food. Very popular. Lentil batter deep fried in oil. You will find it in almost all Indian restaurants. Garnishing would differ. Traditional South Indians serve vada with a couple of sauces (sambhar and chutney) on the side. North Indians serve it as the patty in a sandwich, called vada-pav.

Re:Donut shaped?

[Anonymous Coward]

If slashdot is going to call itself "news for the nerds" the least it can do is to call that shape by its proper name, a torus.

Most people know what a donut is, and don't know what a torus is. Super-nerds seem to often suffer from this disease where they think everyone else is a super-nerd. They can't imagine that not everyone knows what a torus is, or that even other nerds might not know what a torus is. Most people here are computer related, and the torus shape just doesn't come up that often.

Language should be descriptive and open to everyone, not overly technical. It's nice that you're a super-nerd from India, but most of the rest of the english speaking world knows what a donut is.

Re:Donut shaped?

[Anonymous Coward]

What I don't get is how you get to be in the tippy top percentile and not already have exposure to SPDF orbitals, etc..

Did anyone notice that the OP said n-orbitals, which aren't a thing? n is the principle quantum number, but it isn't a type of orbital.

This screams troll.

Re:Donut shaped?

[Anonymous Coward]

you torus a new one

Re:Donut shaped?

[fat man's underwear]

If you're going to write Donut's, why didn't you also write Mind's?

Re:Donut shaped?

[Anonymous Coward]

Most donuts are filled?

Buddy, you ever BEEN to a donut shop?

Statistically, most are missing that middle part. We use special terms to deisgnate the non-toroidal ones.

Re:Donut shaped?

[Lije Baley]

If you say "torus", too many Americans will think you are hitting on the them or talking about an old Ford sedan (Taurus). Besides, I can't imagine that a torus tastes as good as a doughnut.

Re:Donut shaped?

[bill_mcgonigle]

And Dark Matter is like a ghost.

Every so often /. editors post shit to elicit outrage comments rather than topical one. Eyeballs are eyeballs; advertisers don't care.

The readers fall for it hook, line, and sinker every time.

Re: Donut shaped?

[Anonymous Coward]

Traditionally, most donuts were not ringed but were in fact filled, usually with cream or fruit. The reason for the filling was that there was usually some uncooked dough at the center. Then someone came up with the idea of taking out the center to start with.

Re:Donut shaped?

[timere969]

We were freshman in IIT, having passed JEE, head high in the clouds, top 1000 All India Rank, all the orientation speakers calling us creme-de-la-creme of India. First Chemistry 101 class. Reading ahead for the class, our study group found there are some electron orbital stuff, n orbital, p orbital etc. One of them was described to be doughnut shaped. All of us were stumped. We did not know what a doughnut was or what it would look like.

Then one from our study group found an American chemistry text book with pictures. It spelled doughnut as donut, but had a picture. We exclaimed, "It is a damned torus! Why wouldn't they call it a torus? Why use this weird thing donut/doughnut". In the class Prof PJ Narayanan said, "... it says doughnut in the text book. Doughnut is like a vada but it is sweet not savoury, they make in the West..."

If slashdot is going to call itself "news for the nerds" the least it can do is to call that shape by its proper name, a torus.

It is the ghost-like that got me. What are the actual properties of a ghost? Sheet like with holes for eyes?

Re:Donut shaped?

[LynnwoodRooster]

A torus?

A torus is the folk who walk aroun an take photos of stuff an eat at yer local restraunt and thing... Usully show up on big ol bus and wear funny shorts an hats.

Re:Donut shaped?

[MiniMike]

I think they use that term to make sure that everybody knows about donuts. It's a public service.

You have learned something new, enjoy!

Re:Donut shaped?

[Anonymous Coward]

If slashdot is going to call itself "news for the nerds" the least it can do is to call that shape by its proper name, a torus.

Fuck you and your cultural sensitivity. It's a donut, it's always a donut, and anyone who doesn't like it can go to naraka.

Re:Donut shaped?

[sheramil]

A torus comes after Aries and before Gemini.

Re:Donut shaped?

[LynnwoodRooster]

Is that light coming torus or movin away?

Not Theorists!

[Roger W Moore]

Theorists develop the underlying theory of physics by suggesting extensions to existing laws to solve problems or by calculating what existing laws predict for given situations. These physicists have built, and are running, an experiment. They are collecting and analysing the data to test a theoretical prediction of a new model of physics which makes them experimentalists, not theorists.

Re:LOL ... wow ...

[RoccamOccam]

The really odd thing is that it wasn't a backcronym. The researchers just happened to get lucky with the name.

Arxiv version of paper

[As_I_Please]

Here's the pre-print on arxiv: https://arxiv.org/abs/1901.106...

The primary result in this paper is the validation of the experimental design using a scaled-down version. From the paper:

ABRACADABRA-10 cm represents the first step in an experimental search program, which aims to ultimately be sensitive to ADM in the coupling range preferred by QCD axions. Future phases of ABRACADABRA will require larger magnets with higher fields, improved shielding, and strong mitigation of mechanical vibration. Augmenting the techniques described here with a resonant amplification readout and scan strategy will also greatly improve the sensitivity of a future full scale ABRACADABRA detector. We have already begun engineering studies towards designing and building such a detector and ABRACADABRA-10 cm creates a strong foundation for this ongoing work.

Oblig. Bad Car Analogy

[PPH]

don't know what a torus is

Torus is made by Ford.

Re:Oblig. Bad Car Analogy

[DigiShaman]

What?! Why would anyone magnetize a Ford Torus? For the crusher? /ducks

Physicists build donut-shaped magnet

[DontBeAMoran]

Is one of those physicists named Homer, by any chance?

Re:Physicists build donut-shaped magnet

[UnknowingFool]

Mmmmmmm . . . donuts *drools*

Re:Physicists build donut-shaped magnet

[cellocgw]

Is one of those physicists named Homer, by any chance?

You jest, eh? The physicist is named T. Horton, you hoser.

Re:Physicists build donut-shaped magnet

[DontBeAMoran]

That would be the same joke, kind of.

Hang on...

[stealth_finger]

How does having a frozen magnetic field here let you detect the conversion of a thing that may or may not exist into radio waves god only knows how many light years away?

Re:Hang on...

[iggymanz]

The axion was a particle postulated to answer the question of why strong interactions, those between quarks, conserve charge-parity. If it exists it would have detectable properties. The range of its mass, and the fact it could be changed into a photon by a strong enough magnetic field.

Even without considering it a candidate for dark matter, it would be a huge experimental breakthrough for QCD (quantum chromodynamics, our most useful model of quarks and their interactions) theory to find the particle or to confirm it doesn't exist.

Great object

[Sqreater]

CLAPCLAPCLAPCLAP for the acronym - brilliant! But you won't find it because it isn't a particle - unless you have to, then you will, of course. It is a bit of denser space but not dense enough to be a particle. The only thing that came out of the beginning is space in different densities.

that's amazing

[slashmydots]

I didn't know magnets can detect math errors causes by not knowing how gravity and space really work? Need I remind everyone that no dark matter has ever ACTUALLY been detected in any way, shape, or form (pun intended)

Re:that's amazing

[Pfhorrest]

The bullet cluster would like a word with you.

Torus vs. Do(ugh)nut...

[Mister Transistor]

The issue is that the term "torus" has only entered the mainstream public vernacular in fairly recent days. The branch of math that refers to them primarily is Topology. They are referenced, defined and used in general Geometry, but aren't particularly important shapes because there are few examples of Torii in the physical universe. Do(ugh)nuts, Tires,and other things like life preserver/rescue rings make up most of the examples of that shape in the real world. There just are't that many. So, unless you were a Geometry or Topology math wonk you probably didn't know about Torii. Branches of math that use them most have only been around since the early 20th century, so they are not very "main stream", even now at present unless you're a math student or professor you probably have not heard of or ever use the term "Torii" or "Torus".

Now, Do(ugh)nuts have been around since 1847 according to the experts, so they have had nearly a 100 year head start on the public awareness of those delicious rings of fried dough. Hence, more people have heard of Do(ugh)nuts for quite a longer time than torii. Also they are called different things in different locales, sometimes they referred to their specialist examples, such as Crullers, Beneyets (sp?), Bear Claws, Sweet Rolls, Eclairs, Long Johns, Danish, Jelly Rolls, Bismarks, etc. Not all Do(ugh)nuts are Torii, and not all Torii are Do(ugh)nuts.

Anyway, TL;DR is the "Torus" is a niche technical math term, whereas "Do(ugh)nuts" is a common bakery food term, so as such it's much more in the awareness of the mainstream public.

find black cat in a dark room.

[porky_pig_jr]

even a dougnut shaped magent won't help with finding a black cat in a dark room - when it's not there. Researchers tend to forget that a dark matter is nothing more than a figment of someone's imagination.

Re:Virtual particles use a different metric

[PPH]

the topology (road) you see the car on looks flat to you

So it's dark matter making it pull to the right?

April fools

[manu0601]

Today it gets hard to distinguish fundamental physics and April fools' jokes.

Mmm

[backslashdot]

How about a magnet shaped donut instead. That ought to have some uses. Before I eat it.