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Charge balance in observable universe

  1. Aug 4, 2013 #1
    Hi,

    I've been wondering about the charge balance in the known universe, factors that might alter it, and the consequences of any small imbalance that might exist. This is a sort of layman's theory. I don't expect it to be right but I'd love to understand how it can be refuted. I am surely confused on any number of points, and ask only for help in putting my picture of how things work together a little bit more. These are just questions that come up as I am learning.

    This is the line of reasoning that's been bothering me:

    1) I've heard that when a particle crosses the event horizon of a black hole that its electromagnetic forces are transformed in such a way that they no longer have an effect outside the black hole. Is this true?

    2) Since electrons have higher charge/mass than protons, protons should be gobbled up by black holes a little bit more easily than electrons. And once a proton goes in the electron will have an improved chance to escape due to the absence of the electric field attraction of the proton. Even if the electric field of the proton as seen by the electron does not go away entirely but is reduced along the gravitational gradient, that would still be enough to give the electron an improved chance to escape.

    3) As a consequence there would be extra electrons in space. Because the electric field force is so much stronger than gravity, these free electrons would become almost uniformly distributed throughout the universe. Unlike escaped orbital electrons which have a very high energy due to the local charge imbalance these free electrons would have low energy. Would they have a correspondingly lower quantum energy level and wavelength?

    4) In my simple understanding, interactions between free, low-energy electrons and electromagnetic waves would result in low-frequency electromagnetic noise that would be observable. If the free carrier density of space was low there would not necessarily be a detectable attenuation or band absorption or emission. Also because the electrons are very low energy the quantum interaction with electromagnetic radiation would have a different character than with orbitally bound or dislocated electrons we're familiar with. The same interactions would occur but at different frequencies. The band structure would be different because of starting at a much lower level, so absorption and emission of photon energy would have different spectra.

    5) Electron mass would be a kind of "dark matter" that would alter large-scale gravitational calculations.

    6) Because over time black holes would eat more protons, the number of low-energy free electrons would always increase. This would cause the universe to expand a little bit more rapidly over time.

    7) Over time the free electrons would spread out faster than the momentum-driven expansion of the universe.

    8) Because electrons would be almost uniformly distributed over a huge range of local space they would affect the speed of light by giving free space a tiny increase in refractive index. Our measured speed of light would already account for the current large-scale distribution. It's possible that this distribution could look uniform well past the point where charge-balanced matter exists in the universe.

    9) There would be a slight charge gradient from the parts of space containing excess electrons to parts of space with no free electrons. Eventually at the edge of the expanding universe there would be no more free electrons. This should create a very tiny refractive index gradient across the known universe.

    10) If you somehow model the Big Bang as particles and/or energy escaping from a black hole, you might have a charge balance difference from the start.

    11) I wonder if a small charge imbalance would have any effect at all on most measurements we make. Even though there are many instances where we think of a free electron as being incredibly significant, it really seems to be a free electron at a certain energy level or field imbalance that we are concerned with.

    12) Where the free-carrier lifetime of an electron in matter imposes a kind of viscosity on the electron gas, completely free electrons would behave as a non-viscous fluid and have the velocity distribution of an ideal gas. The net velocity of the fluid would be related to the relative locations and density of the sources and be very little affected by gravitational forces or the velocities of the sources.

    Keith
     
    Last edited: Aug 4, 2013
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  3. Aug 4, 2013 #2

    Simon Bridge

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    No - that isn't quite true.
    The effect depends on who is doing the measuring.
    Glibly: Seen from a long way away, energy that gets close enough to a black hole is "thermalized" and returned as "Hawking radiation".

    What leads you to say that? They both fall at the same rate. What about BHs that already have a charge?

    We may imagine an infalling hydrogen atom approaching the Schwarzschild radius ... as far as the H atom is concerned, there is nothing particularly special about that spot in space.

    If the gravity gradient is steep enough, it may rip the atom apart ... since the atom is a quantum structure with the electron best described as a "probability cloud" around the nucleus, it's anyones' guess which gets pulled from what.

    Particles escaping from close to the event horizon can have very high energies - due to various slingshot effects. To get out, it should have started with very high energy anyway. There is no reason to suppose that escaping particles must have low energies.

    The weakness of gravity just means that you need very much more mass to overcome the EM forces. This routinely happens in quite modest stars - it's how the p-p fusion happens in the Sun. Black holes are much much bigger.

    Since the rest of your questions follow from these - I'll stop there.
     
  4. Aug 4, 2013 #3
    Thanks for your reply Simon!

    Indeed I think it was my fuzzy thinking about the probabilities of heavier versus lighter particles going into the black hole that hung me up. I was confused by the idea of the electric field being "hidden" by the black hole and thought about it in an inconsistent way.

    I do want to say that the world is full of mechanisms that separate particles based on their charge/mass ratios. E.g. it will always happen particles describe a curved path through space when there is a fixed electric or magnetic field present. If there was a strong electric or magnetic field that could cause particles to slow down or speed up as they made a "near miss" of falling into the black hole and if that mechanism operated somewhat consistently in different black holes throughout the universe then maybe you could still have a difference in charge balance.

    Unfortunately I don't know what kinds of electric or magnetic fields would be observed by a particle making such a "near miss." Is the environment around a black hole understood in that sort of detail?

    Keith
     
  5. Aug 5, 2013 #4

    Simon Bridge

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    The space-time about a black hole is pretty well modeled - in that sense, "yes" the environment around a black hole is understood in that sort of detail. The thing to remember about relativity is that everything works out pretty much as you'd expect locally - everything depends on where the observer is. If the observer, per your description, is a charged particle ... close to the event horizon, there may be dramatic tidal effects but, apart from that, nothing special beyond that.

    The event horizon is a coordinate singularity - like the ones across the top and bottom of a map of the Earth. Change the coordinate system and it goes away.

    Black holes which accumulate a charge will tend to favorably attract the opposite charge - so would tend towards neutral charge over time.

    Some reading (I've tried to keep it accessible).

    In 10 things you didn't know about black holes -- Phil Platt, food for thought on BHs in general.

    In Space-time geometry inside a black hole Jim Haldenwang covers space-time geometry outside as well.

    Journey into and through a Reissner-Nordström black hole ... illustrates a BH that has charge but no spin.

    ... and this discussion in another forum goes into the electromagnetic field about a charged, rotating, black hole.
     
  6. Aug 5, 2013 #5
    Those are great references! Thank you. They contain good hints on how to start to understand how charged particles close to a black hole might behave. Maybe I can get there eventually.

    I see the answer to at least one more of the things that was bothering me: If there were excess electrons (for example) in the universe then it seems like they would have to spread out in a locally uniform manner, like a gas. And it seems that they would change the refractive index of everything a little bit, including space. I don't know how to calculate the refractive index change from the electron density right now, but I know it can be done and can find the answer. The refractive index change would create a small dependence of the speed of light on the average frame of rest for the electron gas.

    So based on experimental observations of the speed of light we can get an upper bound on the density of unpaired charged particles. That won't bound the absolute charge imbalance but at least it will bound the charge density of the imbalance for a given type of particle. That in turn gives an upper bound on the locally uniform mass density for the imbalance.

    Anyway if I manage to make this calculation I will post it back. I'm guessing it will show that the density of any imbalance would have to be extremely small. This is the method I wanted to understand.

    Thank you again for your help!

    Keith
     
  7. Aug 5, 2013 #6

    Simon Bridge

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    Are you thinking that once a negative charge is paired with a positive charge, the positive charge cannot attract any more negative charges?
     
  8. Aug 5, 2013 #7
    Yes: I was thinking that when equal charges of opposite sign are close together they will tend to remain close and look neutral from a long way away. But when there are excess charges of the same sign they will spread out as far as possible. There is no strong force to restrain them from entering or leaving matter, and their repulsive force is stronger than gravitation. They will still create and interact with magnetic fields, but I don't think this prevents them from spreading out evenly and, at a very large scale, accelerating away from their centroid like an expanding gas. In the middle of the universe they would not have much net motion but at the edges they will have a large outward velocity.

    It sounds like I may have missed something though. Is this different from the way you think free charges would really behave?

    Keith
     
  9. Aug 5, 2013 #8

    Simon Bridge

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    A single proton can attract more than one electron ... the hydrogen anion H-, for instance.
    http://en.wikipedia.org/wiki/Hydrogen_anion
    Hydrogen is not the only atom that can form anions.

    In the macroscopic world, electrons can get stuck in conductors or in the surface of insulators - making the bulk material negatively charged.

    Note: the gravitational force is not always weaker than the coulomb force, it depends on how much mass, and how much charge, there is. A very diffuse negative charge distribution would get warped by accumulations of neutral matter. Central gravitational fields will allow free electrons to accumulate closer together.

    The comparison that makes gravity the weakest is between the force constants.

    It's a big universe, there's lots going on.
     
  10. Aug 17, 2016 #9
    Suppose that an evil villain had access to a black hole and a large amount of hydrogen gas near the black hole. The villain separates the electrons from the protons, drops the protons into the black hole, and uses the energy released to throw the electrons a long distance away. How much of this could occur before effects on celestial mechanics became noticeable? According to my old Halliday & Resnick physics text, it would not take very long.
     
  11. Aug 17, 2016 #10
    Thanks for writing back, even to this old thread. I still think this is an interesting topic. I've continued to be interested in this subject, and in the years since the original post my understanding has evolved and I've gotten partial answers to my original questions. I eventually got considerable help from a professional physicist and cosmologist. He helped me in several ways including finding this reference: http://arxiv.org/abs/1409.3096 .

    I agree with your point, that if even a fairly small charge imbalance exists on a large scale then there are some effects that need to be taken into account in celestial mechanics. My question eventually turned into something more narrow: could part of the "mass deficit" in the theory of galactic structure formation be attributed to uneven distribution of electric charges within galaxies? The contributions to the rotation speed of the arms of spiral galaxies is at least in the right direction. The effect on lensing around galaxies might also be similar.

    On the down side, the electric field needed to counteract the gravitational force enough to make up the difference between the predicted and actual velocities of the galactic arms is very large: maybe 1 V/m near our solar system, according to the reference. It would be surprising if such a thing existed and and we had not detected it.

    So I still think the question is interesting and even though I have not gotten a definitive answer, very likely the question has been asked and answered many times. For example if the hypothesis were true then there would be some observable effects: if we had a nightly count of charged and uncharged particles collected from a satellite-based instrument pointed away from the Earth then we should see a variation over the year. Likewise energy of particles entering our solar system versus their charge/mass ratio should show a directional difference relative to the galactic core.

    Keith
     
    Last edited: Aug 17, 2016
  12. Aug 17, 2016 #11

    Simon Bridge

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    Welcome to PF;
    It depends what you mean by "noticable".

    Which H&R, and what page? What does H&R mean by "not very long"?
     
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