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Dark matter and the solar wind

  1. Mar 14, 2009 #1
    It seems to me that an obvious source of dark matter (and possibly dark energy) might be the massive ejections of spent fuel from our sun in the form of the solar wind. If our sun regularly ejects spent fuel in the form of the solar wind, it follows that the same process must happen in billions of other stars in the Milky Way and across the entire universe. This may sound crazy, but if an approximate mass could be calculated for the amount of material expelled by living stars, it could well be analogous to the amount of so called dark matter we are told is present in the universe.
    Any thoughts?
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    Also, can anyone explain or point to an explanation of the material ejected by the sun in the solar wind, the best explanation I've ever heard is that it's a sort of 'plasma'. We're spending billions of dollars chasing elementary particles around accelerators. Why not use the detector technology at the heart of these detectors on sattelite based instruments capable of detecting and offering science some insight into the particles in the solar wind. If my understanding of the nuclear processes at work within the sun is correct then what is the solar wind but an ejection of sub-nuclear particles. The key point is that the particles in the solar wind are formed in nature and not by man. Shouldn't the objective be to limit the effects of the observer on the observations?
     
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  3. Mar 14, 2009 #2

    Janus

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    For one, dark matter doesn't interact electromagnetically(which is why we can't detect it using the electromagnetic spectrum), while the Solar wind is composed of particles (electrons and protons) which do. The Solar wind helps to supply the matter that makes up the interstellar medium.

    Secondly, during its entire lifetime, the Sun has only lost about 0.01% of its mass as Solar wind, and the ratio of dark matter to normal matter is about 5 to 1. All the solar wind of the all the star in a galaxy only amounts to a fraction of a percent of the mass needed to explain dark matter.
     
  4. Mar 15, 2009 #3

    Chalnoth

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    Wikipedia is usually good for this sort of information:
    http://en.wikipedia.org/wiki/Solar_wind

    Meet WIND:
    http://www-istp.gsfc.nasa.gov/wind.shtml

    There are also other satellites in orbit as well as planned whose mission is, at least in part, to investigate the solar wind. The basic punchline is this: learning more about the solar wind will tell us more about the Sun, and about how to protect our satellites from the solar wind. It won't teach us anything new about fundamental physics.

    Nope. The nuclear furnace of the Sun is deep within its core. Basically the only sort of thing we can directly measure from that nuclear furnace is neutrinos (because they tend to zip right through ordinary matter). The other particles emitted during the nuclear processes just run into the material of the Sun, heating it up. The solar wind is a result of the high temperatures and magnetic fields that happen at the Sun's surface. It is almost completely independent of what's going on deep in its core.

    Oh, and by the way, we have a number of observatories currently measuring the neutrinos from the Sun, as well as other sources. And you might be interested to know that we actually learned something new about fundamental physics from observing these solar neutrinos: that neutrinos have mass. See the solar neutrino problem.

    This is pretty much irrelevant. An electron is an electron is an electron. There is no conceivable way of distinguishing between an electron produced by "man" or through any other process. The same goes with all other fundamental particles. Now, what nature does offer us is certain high-energy processes that produce particles at energies vastly beyond what we can hope to achieve in terrestrial particle accelerators. And we have experiments to measure those too (such as Auger Observatory). But we went beyond the energy regime probed by the solar wind a long time ago (The LHC should be at around a million times greater energy).
     
  5. Mar 15, 2009 #4
    Thanks for that folks. Simple answers to a simple question, I like it!!
    Thanks also Chalnoth for the links, I'll be reading up later.
     
    Last edited: Mar 15, 2009
  6. Mar 16, 2009 #5
    OK, but how many of the particles in the Standard Model have actually been detected as existing freely in nature? I fully accept your explanation why the solar wind could have nothing to do with dark matter. I also accept that an electron is an electron is an electron but I have a problem with the Standard Model as it seems that some of the particles in it have only been detected or inferred from particle accelerator experiments. If I was to smash a crystal vase on the floor, I could come up with a complicated, esoteric mathematics to describe the shards I would find all over the floor but I would be no closer to discovering the processes that caused the vase to come about or what the purpose of the vase was.
     
  7. Mar 16, 2009 #6

    Chalnoth

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    Well, perhaps a short description of how accelerator experiments are performed will help.

    First, the idea of an accelerator experiment is to produce high-mass particles: first we slam two particles together (sometimes electron/positron pairs, sometimes protons/anti-proton pairs, sometimes just protons, or other combinations, all depending upon the accelerator). When we do this, the kinetic energy in the beams is converted to mass energy in the form of new particles. Now, most of the new particles that are produced decay almost instantaneously. But we can measure the stuff they decay into, and add up the quantum numbers to determine what was originally there. For example, if a particle is produced with a specific charge and mass, then adding up the charge and energy of all of the decay products tells us what that charge and mass were.

    There are also all sorts of other measurements that can be done: how long, on average, does it take for this type of particle to decay? How often does it decay in one way versus another? How often is it produced in the kind of reaction we're looking at? Each of these measurements depend upon the properties of the particle in question as well as how it interacts with other stuff. And the standard model of particle physics only allows for very specific patterns between all of these relationships. For example, there's a very specific relationship between the rate of production of a particle and its rate of decay.

    If we were to use the solar wind for this, it would end up being the exact same thing. Except that it would be at about one millionth the energy we are currently using in particle accelerators, an energy so low in fact that we wouldn't be producing any new particles at all, so it would basically be useless for this sort of investigation.

    Of course, we do want independent confirmation of these results, and one way to do that is to look to cosmology. The very early universe, for instance, was hot enough that typical collisions happening at that time are as energetic (or more) as collisions produced in current and future particle accelerators. Therefore what we discover about the behavior of matter in particle accelerators has direct implications as to how matter behaved in the very early universe. So if we take the properties of natural laws that we discover from particle accelerators, and apply those natural laws to the early universe, we should get results that conform with observation. If we don't, then there's something wrong with our theories.

    So far, the agreement is good but not perfect. There are additional effects active in the early universe that we have not yet accounted for in particle physics, namely the baryon asymmetry and the existence of dark matter. But in general the agreement, so far, looks good.
     
  8. Mar 23, 2009 #7
    Quick question Chalnoth:- (Bear in mind I'm a lay nut and just trying to understand!)

    If I shone a light on some dark matter, would it reflect the light or is it completely electromagnetically null?
     
  9. Mar 23, 2009 #8
    No, light will just pass thru the dark matter.
    ordinary matter will also pass thru the dark matter without any resistance
     
  10. Mar 23, 2009 #9

    Chalnoth

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    This is a good answer, but just to add my own little piece: If it did interact with light, then we could see it, and wouldn't call it dark.
     
  11. Mar 24, 2009 #10
    OK, so what are we saying dark matter consists of? Really tiny fundamental particles the likes of which we're only beginning to understand thru particle accelerator experiments? Or something else entirely? Also, if dark matter has mass (this seems to be the reason for the original psotulation that it exists:- to explain mass effects on expansion history of the universe and motion of galaxies) then how does it not interact electromagnetically? We must be talking about some pretty weird material here.
    Could it not just be that our estimates of the amount of matter in the universe based on what we can 'see' are just plain wrong?
    I refer back to the solar wind, we never really 'see' this material until it interacts electromagnetically with this and other planets' magnetic fields, and I'm sure there is plenty of this type of material in our galaxy, not to mention in the intergalactic 'void'. Also, what about planets and planetoids of other stars. Are we sure that we can 'see' or estimate for all the non 'dark' material that's out there that we just can't detect. I mean, our sun has an asteroid belt and another zone beyond the planetary limits which contains a lot of comets etc. Have we factored this type of material in our calculations of how our galaxy and the cosmos in general should operate?
     
  12. Mar 24, 2009 #11
    1 We dont know for sure, there are several ideas (lightest supersymmetric particles, for example, wiki it)
    2 How mass is related to electromagnetism? There are many massive neutral particles
     
  13. Mar 24, 2009 #12

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    Even if our estimate of the amount of total matter in the Solar system in the form of planets, comets, asteroids etc. was too small by a factor of ten, it would still only amount to about 1% the mass of the Sun. So, for such matter to account for the missing dark matter, we would have to miss seeing 99.98% of the matter in the universe.

    Remember this matter would interact with light, including blocking it. If there was 5000 times more of it, it would block off a lot more light from other stars then it does. Instead of the thousands of stars we can see with the naked eye, we'd be down to maybe dozens.
     
  14. Mar 24, 2009 #13

    Chalnoth

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    We don't yet know, but our present knowledge of dark matter indicates rather strongly that it is made up of an as-yet-unknown fundamental particle with no electric charge. Neutrinos were considered early-on, as they have many of the required properties, but it turns out that their mass is too small.

    Other popular options are the lightest supersymmetric particle or an axion. But given that we don't know whether supersymmetry or the theories that predict one or more axions are accurate, we don't know if any of these ideas are correct. It is possible that it's something completely different.

    By having no electric charge. Neutrinos are like this (they're just too light to explain the dark matter), so it's not that exotic.

    Well, there are a variety of reasons why this can't explain our dark matter observations. Basically, our observations force the dark matter to be:
    1. Weakly-interacting.
    2. Have no electric charge.

    We can see this, for example, in the Bullet Cluster where most of the mass is demonstrated to be almost completely unaffected by the collision. There we directly detect that the "solar wind" type stuff is caught in between the two clusters after the collision, while the mass passes through with almost no friction.

    Yes. It was clear from the very first measurements of dark matter that this could not really explain it, as the distribution of mass of the dark matter entirely different from the distribution of mass of the stars.
     
  15. Mar 25, 2009 #14
    Thanks for your replies, especially your patience in explaining these concepts to a lay person and for the links..
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  16. Mar 26, 2009 #15

    Chronos

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    The total mass of dark matter within the orbit of Saturn cannot much exceed that of earth without measurable consequences to planetary orbits.
     
  17. Mar 29, 2009 #16
    Meaning that the total mass of the solar wind at any given time is much greater than the mass of the earth?
    How does your statement above relate to the questions and explanations given earlier in the thread?
    Again, I'm just a lay person trying to understand!!
     
  18. Mar 29, 2009 #17
    How do you know?
    For example (it is my fantasy) imagine that Earth density is less then expected by 5%, and 5% of mass of the earth is a mass of an ultra-cold dark matter residing inside the earth

    In total it gives the same mass of the earth so it will be consistent with all the data we have now...
     
  19. Mar 29, 2009 #18

    Chalnoth

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    Through detailed measurements of the orbits of the planets as a function of distance, we get a really accurate picture of how much mass exists within the Solar System, as well as what its distribution is. There just isn't that much unaccounted for mass hanging around.
     
    Last edited: Mar 29, 2009
  20. Mar 30, 2009 #19
    Chronos:-
    Question for you a couple of posts back
     
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