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Thread: Neutrinos/Plasma in space, charged plasma exchange between bodies.

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    Neutrinos/Plasma in space, charged plasma exchange between bodies.

    So yes sorry my question is prompted somewhat by reading regarding Comet Elenin stuff but before you banish me too quickly to the "Woo Woo Planet X Questions" subforum...

    It strikes me as amazing that we literally swim in a constant bombardment of solar neutrinos. Now of course these particles only interact via "the weak force" but we are awash in them. Before the notion of atmosphere and it's importance to life was fully understood, the manifestation of it in the wind was perceived and the wind was regarded as separate. Later it turns out that components of that invisible stuff is essential to almost all life.

    Before we knew what the solar wind was, we saw the aurora. But now we know that the solar wind treats us to the constant all-penetrating solar neutrino rinse as well as interacting with Earth electromagnetically.

    Now I know that, although consisting of a gazillion tons of material, once the solar matter that is ejected during a CME event reaches us, it is diffuse. But it is a fact that the Earth and other planets earth swim through a varying density of solar wind/plasma bath.

    But can that diffuse plasma bath serve as a conductor/conveyor for the transfer of electrical, electromagnetic or other forces between bodies?

    Also, could the constant solar neutrino bath be good or even essential to life? Do the infintesimal neutrino reactions some how benefit us?

    (where the comet elenin thing comes in is that the usual folk are claiming it will Destroy Us All (DUA) because it is a type of dielectric "super capacitor" that is building up a massive charge. It will come in between the earth and the sun, and as a result will somehow close a giant cosmic circuit that will... well, you know: DUA.)

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    Solar neutrinos have nothing to do with the solar wind. They do not interact or affect one another.

    Of all the rather huge number of neutrinos that pass through a human body, you would have to be unlucky to have even one neutrino interact with your body in your lifetime. You would have to be hit by a car while waterskiing unlucky to have two neutrinos interact with you during your lifetime.

    Plasma can serve as a conductor, and pretty much must serve as a conductor if there are electric fields around. That is why the 'super capacitor' is silly. If Elenin were a 'super capacitor' it is constantly being discharged by the solar wind.

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    Hi, can you point out some plasma in space that doesn't emit neutrinos?
    ***poor choice of words "emit"***

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    Quote Originally Posted by fcunnane View Post
    Hi, can you point out some plasma in space that doesn't emit neutrinos?
    ***poor choice of words "emit"***
    If you didn't mean emit, what did you mean?

    Collisions between cosmic ray (CR) particles and the nuclei of atoms (ions) in the inter-planetary medium, ISM (interstellar medium), etc will produce neutrinos (not every collision, of course!), as will CR particle collisions with the nuclei of atoms in the bodies of human beings, etc. So in this sense every part of the universe where there are cosmic rays will "emit" neutrinos.

    But I think you may have meant something quite different.

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    Quote Originally Posted by korjik View Post
    Solar neutrinos have nothing to do with the solar wind. They do not interact or affect one another.
    Thanks for this info and for making this distinction. I've read about the two separately, and wasn't sure if they were directly related or not. My general question is really "goodness, the sun throws out a lot of stuff, some of which we know and perceive the effects of, and some stuff that we don't: but can we sure that the stuff we are unable to perceive/measure the effects of is really not affecting things on a level we can't measure yet?"

    Quote Originally Posted by korjik View Post
    Plasma can serve as a conductor, and pretty much must serve as a conductor if there are electric fields around. That is why the 'super capacitor' is silly. If Elenin were a 'super capacitor' it is constantly being discharged by the solar wind.
    Thanks, that was exactly what I was thinking: a capacitor builds up a charge, if such a "space borne super-capacitor" actually existed and it were to discharge, it would do so throught the nearest conductor. If a conductive "plasma sea" existed all around it, then any built up charge would discharge through that sea. The potential for it electrically interacting with any surrounding conductive plasma would be based on the density and conductivity of that plasma. So the dreaded "DUA switch" is always in the on position, the bare leads of the capacitor are always exposed to the conductive plasma.

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    Quote Originally Posted by korjik View Post
    Plasma can serve as a conductor, and pretty much must serve as a conductor if there are electric fields around. That is why the 'super capacitor' is silly. If Elenin were a 'super capacitor' it is constantly being discharged by the solar wind.
    I don't know about any "capacitance", but won't the interplanetary plasma cause objects to charge negatively? For example, doesn't interplanetary plasma causes dust to charge negatively, eg:



    Of course this would cause positively charged objects to discharge.

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    Quote Originally Posted by utenzil View Post
    But can that diffuse plasma bath serve as a conductor/conveyor for the transfer of electrical, electromagnetic or other forces between bodies?
    A 2007 NASA press release has this:

    "The [THEMIS] satellites have found evidence of magnetic ropes connecting Earth's upper atmosphere directly to the sun," said David Sibeck, project scientist for the mission at NASA's Goddard Space Flight Center, Greenbelt, Md. "We believe that solar wind particles flow in along these ropes, providing energy for geomagnetic storms and auroras."
    Also, I beleive that ions have been detected by SOHO from Venus's magnetotail "connecting" to earth (ref)

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    Quote Originally Posted by korjik View Post
    Plasma can serve as a conductor, and pretty much must serve as a conductor if there are electric fields around. That is why the 'super capacitor' is silly. If Elenin were a 'super capacitor' it is constantly being discharged by the solar wind.
    While I agree with your "super capacitor" comment, I've been reading around on plasmas and capacitance, and it does appear that dust grains (which I assume are present close to a comet) can have a capacitance. For example:

    We now consider the case of grain charging by plasma collection currents when the grain density in the plasma is high. In this case, the grain charge may be lower than its "isolated" value, as discussed earlier. There are two competing effects that lead to this result; one is that the capacitance of the grain increases, which tends to increase the charge, and the other is that the magnitude of the grain surface potential relative to the plasma potential decreases, which decreases the charge. The capacitance of a grain increases from its value in vacuum (where the capacitance is proportional to the grain radius) as the grain spacing becomes comparable to or less than the Debye length. In this case, the positive sheath (for a negatively charged grain) moves closer to the grain surface, thus essentially decreasing the capacitor gap, or the distance between the edge of the sheath and the grain surface, thereby increasing the capacitance (Whipple et al 1985, Northrop 1992) - Mendis, D. A.; Rosenberg, M., "Cosmic Dusty Plasmas" (1994) Annual Review of Astronomy and Astrophysics, Volume 32, 1994, see "2.2 Grain Ensemble", page 426.
    Obviously this nothing like a "super capacitor", but it does seem that the effect is not completely absent.

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    Photoemission and impacts by charged particles will more easily knock electrons loose than positive ions, so things generally get positively charged and surrounded by a cloud of electrons. On the moon, charged surface dust will even suspend itself off the surface by self repulsion.

    Capacitance usually refers to mutual capacitance between two electrodes, but every object has self capacitance, the amount depending on surface geometry and materials. A capacitor is two plates separated by a dielectric, and its rating is the mutual capacitance between those plates, a supercapacitor is a capacitor with a particularly high rating due to the materials and structures used. A comet (or dust particle) does have capacitance and a net charge, but is no supercapacitor.

    Behavior of surface charges is probably important to understanding formation of the dust tail of comets. However, I don't see any way for it to be of relevance to interactions between the comet and Earth. There's limiting processes...the charge will rise until it reaches equilibrium, with the comet charged highly enough to grab electrons from the solar wind as fast as they're knocked away. The moon is much bigger, much closer to Earth (it even regularly passes directly through the Earth's magnetotail), and is constantly exposed to the sun, its interactions with Earth's magnetosphere are vastly greater than anything we'll see from this tiny comet.

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    Quote Originally Posted by cjameshuff View Post
    Photoemission and impacts by charged particles will more easily knock electrons loose than positive ions, so things generally get positively charged and surrounded by a cloud of electrons. On the moon, charged surface dust will even suspend itself off the surface by self repulsion.
    Photoelectric charging is indeed important, and tends to charge positively. Plasma electrons (charging negatively) will dominate in shadow, and the absence of light. Plasma ions and secondary electrons may also charge. A summary of all these charging mechanisms on the Moon can be found in the paper "Lunar Surface Charging" (2005) (PDF)

    I'm sure I've seen an old Apollo photo of the lunar dusty layer levitating above the Moon's surface, but I don't recall where. Can anyone help?

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    Charging of objects in space is dependent on where the object is located. If there is sunlight then most likely the object will be charged positively because of the UV knocking off electrons. If the object is in the shade then free electrons can attach themselves to the surface and the object will be charged negatively. In both cases however, there will be a sheath formed around the object, because of the high mobility of the plasma in space, which will, over the distance of a few Debye lengths neutralise this charged object, when seen from a distance.

    This means that, should two of these charged objects pass close to each other, that nothing happens as both will "see" a neutral object. So there will also not be any discharges, because the system is in equilibrium. However, charged dust will be very interesting in the surroundings of a cometary nucleus, I am already looking forward to start working on the Rosetta data in 2014.
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    Quote Originally Posted by iantresman View Post
    A 2007 NASA press release has this:
    Ahhhh not again that idiotic press release!!!!!
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    Quote Originally Posted by tusenfem View Post
    Quote Originally Posted by iantresman
    A 2007 NASA press release has this:
    Ahhhh not again that idiotic press release!!!!!
    This document, or references to it or quotes from it, can be found all over the internet.

    One might even say it is often used for a specific purpose, sometimes quite deliberately.

    The shortcomings of the PR, in terms of space science, are much less common, on the internet; indeed, they are quite hard to find (that there are such serious, scientific, short-comings is, as your scream suggests, certain).

    Perhaps you could take some time to address the main shortcomings, tusenfem?

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    Quote Originally Posted by Nereid View Post
    This document, or references to it or quotes from it, can be found all over the internet.

    One might even say it is often used for a specific purpose, sometimes quite deliberately.

    The shortcomings of the PR, in terms of space science, are much less common, on the internet; indeed, they are quite hard to find (that there are such serious, scientific, short-comings is, as your scream suggests, certain).

    Perhaps you could take some time to address the main shortcomings, tusenfem?
    I specifically quoted David Sibeck, project scientist for the mission at NASA's Goddard Space Flight Center. It is his words that need to be addressed, not the press release.

    I am not aware that I wrote anything contentious here, nor why you are suggesting that there are "pernicious myths" (the subject of your link) that need addressing.

    If I have misunderstood anything, I would welcome any corrections.

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    Quote Originally Posted by utenzil View Post
    Also, could the constant solar neutrino bath be good or even essential to life? Do the infintesimal neutrino reactions some how benefit us?
    I was looking for some figures on interaction rates and didn't find anything particularly useful. But this article says that the Gran Sasso detector uses 600 tonnes of liquid argon and has detected 144 neutrinos in 15 months, roughly 10 a month. Say you weigh 1/10,000 of that then you may absorb one neutrino in a lifetime. So I think you can forget about neutrinos as being significant.

    On the other hand, we are constantly bombarded by low levels of background radiation - this may be significant as a cause of genetic change and hence evolution.

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    Quote Originally Posted by iantresman View Post
    I specifically quoted David Sibeck, project scientist for the mission at NASA's Goddard Space Flight Center. It is his words that need to be addressed, not the press release.

    I am not aware that I wrote anything contentious here, nor why you are suggesting that there are "pernicious myths" (the subject of your link) that need addressing.

    If I have misunderstood anything, I would welcome any corrections.
    No, it IS the press release that needs to be discussed, because Dave should have READ the release before he let it get out. I have no time at the moment to go through it all, but the "ropes connecting the Sun to the Earth" comment, for example: Yes THEMIS measured this big long magnetic rope, but no they did not find that it was connected to the sun. Yes, activity of the Sun will lead to aurora, BUT the main particles that create the aurora are magnetospheric particles and not solar wind particles, as Dave should clearly know. The substorm in the beginning of the press release, discussed by Vassilis has completely NOTHING to do with the magnetic rope, because THEY HAPPENED ON DIFFERENT DAYS. Etc. etc. etc. These kinds of press releases makes for very muddy waters.


    HOWEVER, TO ALL this is nothing to be discussed in this thread, so this is the END.
    One can take it to a pernicious thread if you like (I would if I knew what pernicious meant), but no more here in this thread.
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  17. 2011-Sep-05, 03:09 PM
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    Just noticed Admin comment to not discuss this

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    Quote Originally Posted by tusenfem View Post
    No, it IS the press release that needs to be discussed,

    HOWEVER, TO ALL this is nothing to be discussed in this thread, so this is the END.
    I'm a little confused, I assume this means that none of the content of the press release should be discussed, including the science therein? And without wanting to sound difficult, I don't understand why, when it relates to the original poster's question. Will await clarification.

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    Confused indeed. IF you have a problem with any Moderation then report the post, do not discuss it in the thread!
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    Science by press release is not the way to go. The explanation that Dave is giving is rather flawed and in all the whole press release is mixing up two different events as I said, and there are real papers in which the science is correctly discussed, that is why, IMHO, this press release should not be used here.
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    Quote Originally Posted by tusenfem View Post
    Science by press release is not the way to go. The explanation that Dave is giving is rather flawed and in all the whole press release is mixing up two different events as I said, and there are real papers in which the science is correctly discussed, that is why, IMHO, this press release should not be used here.
    Sure, isn't this how we all learn? I have other NASA web page to mention, and would love to get to the scientific papers, all of which seem (to me) relevant to the original poster's post.

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    No, that is how one gets great misunderstandings on how plasma works because one never bothered to actually learn the concepts from first principles. It is also how one gets great misimpressions on the relevance to the OP cause one dosent actually know how plasma works

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    Quote Originally Posted by utenzil View Post
    My general question is really "goodness, the sun throws out a lot of stuff, some of which we know and perceive the effects of, and some stuff that we don't: but can we sure that the stuff we are unable to perceive/measure the effects of is really not affecting things on a level we can't measure yet?"
    This is, I think, a really good question!

    How do we, scientists*, go about trying to answer such questions?

    Here are a couple of thoughts:

    -> if we can't measure it, yet, how can - how could - we know we know it even exists? An imperceptible, unimagined cause is, almost by definition, beyond the scope of science

    -> if our best theories, which we've tested 55 ways to Sunday, suggest there's something that might be measurable, then we can develop hypotheses and go test them! In principle anyway.

    -> if you (or anyone else) has an idea about what might be happening (to affect things on a level we can't measure yet, but is a real effect nonetheless), then you can develop that idea to the point where it's sufficiently quantitative that you can actually go test it (again, in principle). Contrariwise, if your novel idea - no matter how beautiful it may seem - cannot be developed into a testable form, then what use is it?

    But I'm curious to know how you'd answer your own question! Care to try?

    * that includes you, utenzil!

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    Quote Originally Posted by korjik View Post
    No, that is how one gets great misunderstandings on how plasma works because one never bothered to actually learn the concepts from first principles. It is also how one gets great misimpressions on the relevance to the OP cause one dosent actually know how plasma works
    BAUT is a discussion forum. I quite agree that some sources are more or less useful than others, but who would know that even NASA scientist can't be relied upon for information? But more importantly, if we can't discuss it, and learn, what's the point of a forum?

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    Quote Originally Posted by korjik View Post
    that is how one gets great misunderstandings on how plasma works because one never bothered to actually learn the concepts from first principles
    Two points.
    1. If we could work out how the universe works from first principles, wouldn't we know a lot more than we do?
    2. I don't believe you can always make predictions from first principles. A good examples of this is the behavior of plasma flow along a curved magnetic field. At the time all the theoretical predictions were wrong, demonstrating that you can't always rely on first principles. (ref: Lindberg, L., "Plasma flow in a curved magnetic field", Astrophysics and Space Science, vol. 55, no. 1, May 1978, p. 203-225.


    I believe that at the very least, it has been constructive to discuss this.

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    STOP this metadiscussion!
    This has nothing to do with the OP.
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