back to article Dark matter? More like diet matter: Super-light axions may solve universe's mass riddle

Boffins have calculated the mass of axions, which are a promising candidate for the mysterious dark matter loitering in our universe. Axions are up to ten billion times lighter than an electron, according to new supercomputer simulations of the early universe. With these figures in mind, scientists can now fine tune their …

  1. Pascal Monett Silver badge
    Coat

    "Topological quantum fluctuations in quantum chromodynamics"

    Inverse the polarity now !

    Um, sorry, for a minute there I thought I was reading an excerpt from a ST:TNG episode.

    1. Richard 12 Silver badge

      Re: "Topological quantum fluctuations in quantum chromodynamics"

      Space is bent and changes colour.

      1. Olius

        Re: "Topological quantum fluctuations in quantum chromodynamics"

        "Space is bent"

        Has anyone told M Khan?

        1. Anonymous Coward
          Anonymous Coward

          Re: "Topological quantum fluctuations in quantum chromodynamics"

          > Has anyone told M Khan?

          Check your privilege!

          1. Olius

            Re: "Topological quantum fluctuations in quantum chromodynamics"

            Check my what now?

            If you're too young to remember Mary Whitehouse, you could at least google "M Khan"...

        2. Swarthy

          Re: "Topological quantum fluctuations in quantum chromodynamics"

          "Space is bent and creates a rainbow."

          -M Khan

    2. King Jack
      Boffin

      Re: "Topological quantum fluctuations in quantum chromodynamics"

      You forgot to say 'rotate the shield harmonics and patch in the secondary EPS conduits'.

    3. Pirate Dave Silver badge
      Pirate

      Re: "Topological quantum fluctuations in quantum chromodynamics"

      "Um, sorry, for a minute there I thought I was reading an excerpt from a ST:TNG episode."

      I kept expecting to read :

      and the Librarian replied "Ook! Ook!!"

  2. Michael H.F. Wilkinson Silver badge
    Coat

    Would those be

    Euclid's axions? Never took those lightly myself.

    OK, OK, I'll get me coat. The one with the book on geometry in the pocket please

  3. lglethal Silver badge
    Trollface

    To paraphrase Red Dwarf

    The thing about Dark Matter is that it's dark, and the thing about Space, your basic description of Space, is its dark. So how are you supposed to see the Dark Matter?

    1. Mephistro
      Facepalm

      Re: To paraphrase Red Dwarf

      WHO THE FUCK DOWNVOTED THAT???

      And why?

      1. Anonymous Coward
        Anonymous Coward

        Re: To paraphrase Red Dwarf

        You can get downvotes round here now for stating that the cloudless daytime sky is blue. I assume it's lunatics who hold a grudge against your previous comments because you disagree with them.

        1. Olius

          Re: To paraphrase Red Dwarf

          I assume it's lunatics w̶h̶o̶ ̶h̶o̶l̶d̶ ̶a̶ ̶g̶r̶u̶d̶g̶e̶ ̶a̶g̶a̶i̶n̶s̶t̶ ̶y̶o̶u̶r̶ ̶p̶r̶e̶v̶i̶o̶u̶s̶ ̶c̶o̶m̶m̶e̶n̶t̶s̶ ̶b̶e̶c̶a̶u̶s̶e̶ ̶y̶o̶u̶ ̶d̶i̶s̶a̶g̶r̶e̶e̶ ̶w̶i̶t̶h̶ ̶t̶h̶e̶m̶.̶

          FTFY (and upvoted, of course) :-)

      2. mr.K
        Boffin

        Re: To paraphrase Red Dwarf

        Given that topological quantum fluctuations in quantum chromodynamics result in a violation of time symmetry, me thinks the reason is quite clear.

        1. Mephistro

          Re: To paraphrase Red Dwarf (@ mr.K)

          Yes! It was the chicken!

    2. David Nash

      Re: To paraphrase Red Dwarf

      Red Dwarf notwithstanding, that is indeed the fundamental problem with dark matter. It's why it was given the name.

  4. David 66

    Wot no Boffinry?

    What are "researchers", and what is this "research" they supposedly do?

    1. Anonymous Coward
      Holmes

      Re: Wot no Boffinry?

      I suggest we setup a team of Boffins to find this elusive "researcher", possibly of greater mass than we previously detected...

  5. Michael H.F. Wilkinson Silver badge
    Happy

    No mention of MACHOs either

    MAssive Cold Halo Objects were also once a contender for dark matter. MACHOs vs WIMPs was such a nice name for a scientific controversy.

    1. Swarthy

      Re: No mention of MACHOs either

      I think it was shown that the MACHOs would just be WIMPs putting on a show....

  6. arctic_haze

    DAMA and her mysterious WIMPs

    The arguments for axions as the dark matter gets stronger the longer no WIMPs are discovered. And not only the WIMP dark matter detectors but also LHC which was supposed to find supersymmetry particles (strongest WIMP candidates) by now. Discovering supersymmetry would be a great step forward and much more fun than axions but the nature likes to play tricks on us.

    By the way it is not true that no WIMP detectors had any results. The Italian DAMA have been seeing an unexplained seasonal change of signal which may be a result od Earth changing its speed versus the galactic dark matter particles while circling the sun. The problem is no one is able to reproduce the result.

    http://www.nature.com/news/controversial-dark-matter-claim-faces-ultimate-test-1.19684

    1. Charlie Clark Silver badge

      Re: DAMA and her mysterious WIMPs

      The arguments for axions as the dark matter gets stronger the longer no WIMPs are discovered.

      That's not logical. They are competing but generally unrelated hypotheses (one will not necessarily disprove the other) both of which have merits but also problems which is why more empirical research is required. I'm pretty sceptical about the axion theory but then again much quantum theory is odd, especially the bits dealing with mass.

      We may well need another Newtonian/Einsteinian/Paulian moment to come up with a new theoretical approach.

      1. arctic_haze

        Re: DAMA and her mysterious WIMPs

        Yes, that's not logical but human being are not completely logical as Mr. Spock will notice in a few centuries.

        So you misread my comment. I was simply stating the fact that more researchers get interested in axion research the longer the search of WIMPSs brings no results (except for the controversial DAMA ones). According to Web of Sience, papers having "axions" AND "dark matter" in the title or abstract or key words were cited 1628 times in 2014 and 3248 in 2015 (a 100% increase in one year).

        Which does not change the fact we are not even certain axions exist. I'm also still not convinced.

        1. Rich 11 Silver badge

          Re: DAMA and her mysterious WIMPs

          but human being are not completely logical as Mr. Spock will notice in a few centuries.

          Mr Spock has already noticed this, having visited Earth in our past.

          1. This post has been deleted by its author

          2. David Nash

            Re: DAMA and her mysterious WIMPs

            "Mr Spock has already noticed this, having visited Earth in our past."

            Yes but he noticed in our future, prior to visiting our past!

    2. Axman

      Re: The problem is no one is able to reproduce the result

      If you can't reproduce it, I'd suggest it wasn't a result.

  7. Charlie Clark Silver badge

    Dark, as in invisible

    "dark" used in the terms "dark energy" and "dark matter" merely refers to our inability to detect something posited to account for observations that are counter to theory: these are values plopped into equations to make them balance. "Missing" might be a better term but names are hard™.

    1. Anonymous Coward
      Anonymous Coward

      Re: Dark, as in invisible

      Or "dark" because it doesn't emit anything appreciable in the EM spectrum, where most of our observations still are? Most of the "visible" matter emits some kind of EM radiation.

      1. Charlie Clark Silver badge

        Re: Dark, as in invisible

        Most of the "visible" matter emits some kind of EM radiation.

        Not really: those bloody neutrinos don't for a start and elsewhere radiation is tied to changes in energy sates. What most matter tends to do is interact with EM radiation or other particles. Hence, the "WI" in WIMPS – weakly interacting. This is why "dark" is so confusing. If we had a way of visualising gravity then these things could be very bright indeed.

        But until we come across something that more or less validates the theories it could be anything including a bunch of photons doing something odd, which as any fule nose, also have mass.

    2. Anonymous Coward
      Thumb Up

      Re: Dark, as in invisible

      A million up votes for you. Why? Because when people call it "the dark side" when they mean the far side, and not the "side facing away from our sun", I have great regret they never tried to understand the world they live in.

      PS, and don't even get into "does a photon have mass" discussion without first confirming we are not talking about (the now redundant?) term of "rest mass".

  8. Hairy Spod

    stupid question

    What do these axions do?

    1. Fading

      Re: stupid question

      Well you know when you were doing long division way back at school and you had a big number being divided by a smaller number - and at the end you had a remainder? The boffins have added up all we know about how the universe is and measured it against what we have observed about the universe and there is a remainder left (not be confused with a remainer which is a brexit free-radical)

      Some of the boffins postulate this remainder is made up of WIMPS that have a certain mass, others that it is made up of many more axions which may have the mass this super computer in the article has calculated.

      What they do is hang around all the other subatomic particles and give them a bit more gravitas.

      1. Anonymous Coward
        Anonymous Coward

        Re: stupid question

        "What they do is hang around all the other subatomic particles and give them a bit more gravitas."

        I conclude from this that our Parliamentary system is axion-deficient.

        1. Destroy All Monsters Silver badge
          Angel

          Re: stupid question

          Frank Wilczek, who likes Axions, on Axions:

          Time’s (Almost) Reversible Arrow

          The laws of physics work both forward and backward in time. So why does time seem to move in only one direction? One potential answer may also reveal the secrets of the universe’s missing mass.

          The though occurs that with that kind of mass, axion particles are REALLY hard to localize, slipping away under the Heisenberg uncertainty principle...

          (Holy Particle Icon Seems Appropriate)

          1. richardcox13

            Re: stupid question

            > The laws of physics work both forward and backward in time.

            Except the Second Law of Thermondynamics.

            Which gives time only one direction.

            1. Destroy All Monsters Silver badge

              Re: stupid question

              That's a macro law, essentially saying that random walks are bound to end up in state spaces that are large rather than small (spontaneous disassembly is more likely than spontaneous assembly)

              Here we are talking micro law: is the set of allowed subatomic interactions going forward the same as the set of allowed subatomic interactions going backward? Amazingly, it's "no". Amazingly, this "no" should occur more evidently than it does. Hence, Axions to bulldozer this particular problem.

    2. Axman

      Re: stupid question - what do these axions do?

      The dirty low paid jobs mostly.

  9. Mark 110

    Is it not possible?

    Is it not possible that the hole in the mass of the galaxy equation is caused by many particles (or other things that impact on the equation) that we haven't identified yet. They keep going in search of a one missing particle that will make the maths add up. If theres a million missing particles we haven't identified yet all of different mass then they are surely never going to find the answer unless we develop the tools to examine those particles.

    Personally I think there may be a huge error in the dark matter theory in the first place though I will probably not live long enough to find out.

    1. Anonymous Coward
      Anonymous Coward

      Re: Is it not possible?

      What is known is that the dynamics of galaxies does not match our understanding of gravity. Missing or dark matter is an hypothesis as to the cause. There is a different anomoly on very large scales for which the hypothesis is dark energy whatever that may be. Dark matter may not be the correct explanation but attempts to modify the dynamics/gravity are not promising. The nature of dark matter if it exists is very much up for grabs. My personal niggle is that there are two different anomolies at different but large scales it would be nice if they had a single or at least related explanation. Dark matter does not do that but it is a relatively conservative and therefore more likely explanation. What is exciting is that there are clear observations showing something is missing from our current understanding and therefore the opportunity to learn more.

      1. Anonymous Coward
        Anonymous Coward

        Re: Is it not possible?

        What if stupidity had mass? There's more than enough of that around to explain away the whole dark matter idea.

        Of course, if stupidity does have mass, that then opens up the challenge that love, hate, information (data) or knowledge (understanding) might also have positive or negative mass. I know the conventional wisdom is that these things don't have mass, but I bet they haven't checked at the sort of weights being posited for axions.

        1. phuzz Silver badge
          Boffin

          Re: Is it not possible?

          "What if stupidity had mass?"

          Knowledge is power.

          Power is energy over time.

          Energy can be exchanged for mass using the formula everyone knows, E=mc^2

          Therefore knowledge can be converted into mass, this may mean that stupidity can produce anti-gravity.

          (joke blatantly stolen from pterry)

        2. W4YBO

          Re: Is it not possible?

          "What if stupidity had mass?"

          It does, and is normally referred to as "dumbass."

        3. Captain DaFt

          Re: Is it not possible?

          "What if stupidity had mass?"

          Doesn't it? The most common comment made about stupid people is how dense they are.

      2. Doctor Syntax Silver badge

        Re: Is it not possible?

        "What is known is that the dynamics of galaxies does not match our understanding of gravity. Missing or dark matter is an hypothesis as to the cause."

        An alternative hypothesis could be that our misunderstanding of gravity is the cause.

        1. Ian Tresman

          Re: Is it not possible?

          The dynamics of galaxies does not work because it omits electromagnetic forces and the fact that 99.999% of the universe is in the plasma state.

    2. Charlie Clark Silver badge

      Re: Is it not possible?

      If theres a million missing particles we haven't identified yet all of different mass

      Well, while initially restating the WIMP theory, you then go ahead and spoil it by driving a coach and horses through it: quantum theory doesn't allow for "millions" of particles and the heavier ones are generally extremely unstable.

      WIMPs provide a solution by having few heavy particles (of a known eV mass); Axions do it by having lots and lots of light particles (the mass of which has now been calculated). Checking for Axions should be easier because they're lighter and it will require less energy in the particle punisher of choice to create them. In theory.

    3. Anonymous Coward
      Anonymous Coward

      Re: Is it not possible?

      "If theres a million missing particles we haven't identified yet all of different mass then they are surely never going to find the answer unless we develop the tools to examine those particles."

      The point here is that we cannot currently observe any of these hypothetical millions of particles. All we can do is consult the Standard Model and a few spin off ideas to get a clue as to what particles might exist that don't reveal themselves to our sensors. Since the number of fundamental particles needed to explain matter and radiation is really quite small, there are no a priori grounds for thinking there are vastly larger numbers waiting to be discovered.

      The idea is to look for possible "holes" in the model and see what might fit into them. Heavy particles that don't feel the EM force are one candidate, because we wouldn't be able to see them and they would not be attracted to the electron clouds or the nuclei of "normal" matter so they would rarely interact.

      The neutrino was a very hypothetical particle for a long time because it was unobservable. It was, effectively, the first form of dark matter until detectors improved and it turned out the the universe is full of the little buggers. Axions could be the next one down. Neutrinos were "invented" to explain a serious problem in physics - beta emission seemed to be violating Newton's laws of motion and conservation of energy. The idea that a small family of particles accounts for a big physical problem - whether it's the existence of matter, beta decay or there not being enough matter - is sufficiently well established that it's going to be the standard approach.

  10. Mage Silver badge
    Alien

    1922 or 1977?

    Axions on Wikipedia

    The axion is a hypothetical elementary particle postulated by the Peccei–Quinn theory in 1977 to resolve the strong CP problem in quantum chromodynamics (QCD)

    (I'm nearly sure it's time and not colour)

    Or there is some other explanation for the cosmic observations and/or solution to the strong CP problem, which might be unrelated anyway.

    1. Anonymous Coward
      Anonymous Coward

      Re: 1922 or 1977?

      I assume, due to T invariance, "colour" is a better descriptor, as "time" is rather relative, so using the other description gives a fixed property to describe.

      You would then describe it as "time" once talking about an entire system. But a single particle experiences no time (think of a photon travelling at the speed of light). However the interactions do... though I think every interaction effectively is a re-emission or interaction in the quantum field...

      It gets rather complicated, but I'd go with their definitions for now. They have spent a long time getting it wrong (learning! :D ) to get to where we are now, and I'd not want to start getting it wrong too much by renaming again.

    2. Rattus Rattus

      Re: 1922 or 1977?

      @Mage: Nope, it's colour. The strong nuclear force has three types of "charge" which physicists have chosen to refer to as "colour" charge: +/- red, +/- green, and +/- blue.

  11. CustardGannet
    Headmaster

    "ten billion times lighter than an electron"

    If item A is 10 billion times *heavier* than item B, this does not mean item B is 10 billion times *lighter* than A.

    I believe the phrase you're looking for is "one 10-billionth of the mass of an electron".

  12. Harry the Bastard

    this one on arxiv....

    https://arxiv.org/pdf/1606.07494.pdf

    ...looks like it may be the paywall-free equivalent, same diagrams

  13. deconstructionist

    Intresting

    Interesting research But there are many theories even conjectures on the precise nature of Dark matter but this kind of science which states it must be particle based bemuses me, what like the graviton and gravity.

    Dark matter at moment is more of an effect rather than force or a particle, Christ it could even be quantum gravity so I have my skeptic hat firmly on again , as we are doing that forcing pegs into holes again.

    1. nijam Silver badge

      Re: Intresting

      > ... science which states it must be particle based ...

      The whole point about quantum theory is that it really doesn't say anything is a particle or a wave, only that it may have those aspects when observed in a particular way. In this case, axions are particles for the purposes of writing an article like this one - but that's because it's convenient notation, not because axions are purely particles and have no wavelike aspect at all.

      1. deconstructionist

        Re: Intresting

        you missed the point which is par for the course in here. dark matter is only an effect we witness, it does not need to be an attribute of a particle or derived from.Just like gravity.

        Discourse on the nature of Quanta is hard when we don't really understand the quantum world but hey never that's stopped the EL REG before ...guys why don't you just drop this section like the other dead sections?

  14. Ugotta B. Kiddingme

    another potentially stupid question

    Please bear with me. Just trying to learn.

    Why is the mass of subatomic particles expressed in eV - by definition, a unit of energy? Yes, I understand that energy can be exchanged for mass and vice versa using (e=mc^2) but why force the conversion calculation? Why isn't there a mass standard to apply?

    The gram would seem to be far too large a unit for this particular task and I suppose expressing something as "0.000000001 yoctograms" is cumbersome, but still. Please enlighten me.

    1. Destroy All Monsters Silver badge

      Re: another potentially stupid question

      Actually it is expressed in eV/c² but the /c² is generally elided (and c chosen to be "1")

      According to E = m * c² giving E and diving by c² yields the mass.

    2. Anonymous Coward
      Anonymous Coward

      Re: another potentially stupid question

      Apart from DaM's comment above, the basic reasons are (1) convenience - it's a mass-independent measure of energy and (2) history - Einstein's formula got really interesting when it was realised that if a photon had an energy greater than 2mc2 where m is the electron rest mass, it could decay into an electron and a positron in Compton scattering; below that energy the decay was not possible. The maximum energy of a photon produced by an electron striking a target in a vacuum tube, is of course related to the PD between anode and cathode in volts, and the electron charge. So eV, keV and MeV are natural units for this sort of thing.

  15. Anonymous Coward
    Anonymous Coward

    Not WIMPs?

    Why are axions not WIMPs? As I understood the term, "massive" in this context meant having mass, not that WIMPs had to be especially enormous. Is it that axions are not weakly interacting?

    1. Anonymous Coward
      Anonymous Coward

      Re: Not WIMPs?

      Actually "massive" is actually meant to be "massive", around Top Quark mass, 100 GeV or so. And they would indeed interact with normal matter via "weak interactions". Axions would interact with magentic fields only (don't ask me why!). The Wikipedia articles seems actually bretty gud:

      Axion

      WIMP

  16. steamrunner

    OK, they're making this sh*t up now aren't they? "Trillions of a thing (that we're not sure of) inside a cubic centimetre of a random bit of the universe"? This is surely just scientific people having a giggle after too many late night pints and drugs, right? Or someone is missing some decimal points or exponentials on their old HP Calculator and hasn't realised whilst calculating their Sainsbury shopping bill?!?

    1. HamsterNet

      Nope,

      Just take the Neutrinos flowing from just our local tiny Sun. Right now around 65 billion neutrinos per cubic CM per second flow through you.

      1. Doctor Syntax Silver badge
        Coat

        "Right now around 65 billion neutrinos per cubic CM per second flow through you."

        The trouble with all these billions of neutrinos and trillions of axions it's difficult to find room for anything else.

        Mine's the one with not much in the pockets.

        1. Anonymous Coward
          Anonymous Coward

          Stranger!

          The fun thing around here is that as long as you stay below some critical mass density and (in case of fermions) avoid having exactly the same state, you can cram all you want into the head of a pin.

          > Trillions of a thing

          It's actually one thing: The axion field, which is energized enough to yield a few trillions of axion quanta.

        2. David Nash

          it's difficult to find room for anything else.

          Except, it's not. Because they are barely interacting with anything else.

    2. Destroy All Monsters Silver badge

      Dude!

      The vacuum is basically a solid, layered material of various "fields" (in particular, the gravitational and electromagnetic fields), and a superconductor for the color force. On top of that it carries the stupendously large "quantum reality", at least at "small amount of bits". Ain't nothing fun about that.

  17. Captain DaFt

    What if they're simply overthinking it?

    (Bear with me, I may have a point)

    Galaxies don't behave right (according to theory), unless you add dark matter.

    Dark matter has been "observed" around galaxies by how much they bend light via gravity.

    But, dark matter hasn't been observed anywhere there isn't matter, no clumps of it free floating around screwing up astronomical observations.

    If it has mass, and is gravitationaly attracted to mass, it should clump. unless:

    Dark Matter isn't a thing, it's an effect, generated by matter.

    How? What would matter affect this way? Space?

    Why not? Gravity has been shown to pull, twist, stretch and bend space, is it possible that it also induces a "false mass" in space the way a moving magnetic field induces a current with its own counter magnetic field in a conductor?

    But since gravity is a unipolar force, the inducted force would not be a counter force, but the same.

    Therefore, The DaFt Theory:

    "Dark Matter" is an effect generated by mass (or its equivalent energy) acting on Space as it moves through it.

    There >dusts off hands< that's my bit of crackpot theorising for the day.

    1. Anonymous Coward
      Anonymous Coward

      Re: What if they're simply overthinking it?

      You're missing something very important here.Why does matter clump?

      The answer is that gravity pulls the particles together. True. But where does the energy go when they collide? The short answer is that it goes to form bonds - chemical, such as hydrogen bonds or valence bonds, or nuclear in neutron stars. But for this, when two particles collide one of two things would happen; they would recoil elastically preserving momentum, or they would annihilate.

      Dark matter is nowadays so called because it does not feel the EM force, so it does not interact with photons and has no charge. That means that when two dark matter particles collide, they repel elastically with the same momentum. They do not clump because kinetic energy is not lost (I know that last sentence isn't very rigorous). Because they feel no EM force, they are not attracted to ordinary matter and will normally go straight through it.

      So galactic haloes of dark matter are what you get due to the influence of gravity on fast moving particles, but the orbits they are in remain pretty stable, and that's why they don't clump. There is nothing to slow them down except over multi-billion-year timescales.

    2. David Nash

      Re: What if they're simply overthinking it?

      Gravity itself is just an effect on space, caused by mass, no? ie. General relativity. So you are proposing an extension to that, dependent on the motion of said mass?

  18. PGTART

    theregister should look for emerging gravity cause dark matter doesnt exist, its a new theory.

    darkmatter was there to fix things no its no longer required to describe the universe, and efficient as the unviverse is it wouldnt act like fixing itself

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