h a l f b a k e r yContrary to popular belief
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So, I was wondering about dark energy and dark matter.
If
you know about such things, skip the next two
paragraphs
or, better yet, the entire idea.
Dark matter: it seems that galaxies are spinning around
too fast to be held together by their own gravity.
Therefore, we have to postulate
some additional,
invisible
mass (dark matter) to provide the gravitational glue to
hold all the stars together in a galaxy.
Dark energy: the universe is expanding (post big bang)
but,
oddly, the rate of expansion is increasing. This is the
opposite of what you'd expect: gravity should be pulling
everything back and slowing the expansion. Hence 'dark
energy' as a mysterious provider of force to account for
the
accelerating expansion.
Hmmm. Here is a stupid alternative suggestion.
Suppose that the cores of galaxies tended to be positively
charged overall, whilst their outer regions were
negatively
charged. This might happen (in my simple world view)
because, whenever protons and electrons find themselves
alone in interstellar space, the heavier protons are
gravitationally pulled gently towards the galactic core,
whereas the much lighter electrons are much less pulled.
It might also happen because radiation pressure will tend
to drive isolated electrons away from the galactic core to
a
greater extent than it drives the heavier protons away.
You might, therefore, have galaxies with positively
charged cores and negatively charged peripheries.
At the centre of such a galaxy, the density of matter
would be enough to
hold things together against their electrostatic repulsion.
At the periphery, electrostatic attraction would keep the
negatively charged outer stars bound to the positive
inner
core. Remember that electrostatic forces are about
10^34
times stronger than gravitational ones, so a small charge
difference would make a big contribution. Gadulka! No
need for dark matter.
Now to dark energy. Atoms in a solid repel one another
because, although each atom is neutral overall, the
negative outer shells of the atoms prevent them getting
too close. In effect, each atom only "sees" the outer
layer
of electrons of its neighbours.
If all the galaxies have negative "shells" around positive
cores, then there will be a net repulsion between
galaxies
and, gadulka! No need for dark energy.
It's also been noted recently that more galaxies spin one
way than the other, in the universe. I'm sure there's
some
sort of alignment-of-dipoles argument to be had here.
Question: Why isn't this an explanation for "Dark Matter"?
http://www.bbc.co.u...nvironment-13416431
I may be showing my ignorance on this one - but, if they've counted all the stuff that emits light, but their calculations don't come up with the answer they'd expect - how about including all the things (like what's in the link) that they can't see? Presumably, that's an oversimplification - but can someone explain why that's an oversimplification? [zen_tom, Nov 14 2012]
No-hair theorem
http://en.wikipedia...iki/No-hair_theorem
Black holes have mass, charge and angular momentum ... and that's it. [Wrongfellow, Nov 14 2012]
Kata/Ana viseo games
Kata_2fAna_20Alter-Dimension_20Games
Speculation herein about the behaviors of extraplanar objects of all sorts. [bungston, Nov 14 2012]
[link]
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Hmm. I'm not sure I'm on board with this idea of
free-floating electrons and protons. It seems to me
that they would tend to find each other within
their localized area of space, thus canceling each
other out pretty quickly. As you said, the
attracting force between protons and electrons is
far stronger than gravity, indicating that isolated
electrons and protons would be attracted to each
other despite gravitational pull. |
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//Remember that electrostatic forces are about
10^34 times stronger than gravitational ones, so a
small charge difference would make a big
contribution.// |
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Given the tremendous mass of a galaxy, you'd still
need a LOT of isolated protons and electrons to
overcome the force of gravity. |
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But then again, I do like the fractal nature of this
theory, so I'm inclined to award a bun for sheer
elegance. |
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Do the electrostatic forces work over that great a distance? It was my understanding that gravity is the farthest-acting force even though it is the weakest. Then again I learned that at an American high school so it is probably wrong. |
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//Do the electrostatic forces work over that great
a distance?// |
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Yes, both gravity and electric forces fall off as the
inverse square of the distance. |
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In the case of galaxies with negative "shells" and
positive "cores", the net repulsive effect will fall
off more quickly. Basically, when two such
galaxies are far apart, the negative "shell" of one
is only a little bit closer (proportionally) to the
negative shell of the other than it is to the
positive core. But there's still an effect. |
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I think it's time to invent my *string theory bikini*. |
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Next time eat about 1/3 less brownie. |
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But don't most galaxies have a black hole at their
core? If this is the case then in your model it would
be a black hole made from protons and I'm not sure
electrostatic forces would be able to escape from it.
The current induced by gazillions of protons orbiting
the black hole at near light speed as they spiral
down to their demise would be impressive though. |
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// The current induced by gazillions of protons orbiting the black hole at near light speed as they spiral down to their demise would be impressive though. // |
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Correction, there would be a large magnetic field, not a current. |
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I don't buy your reason for neutrally charge galaxies repelling each other. Electrostatic force can be calculated like gravitational force. If there is a sphere (or shell) of negative charge, the force can be calculated as if the charge is concentrated at a point at the center. A similar calculation can be done with positive charge. If the total charge is the same and the center is the same, then there will be no attraction to a charged particle (or galaxy) at a distance. |
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I would assume (possibly incorrectly) that on an atomic scale, neutral atoms wouldn't attract or repel each other until they were within the distance of their outer electron shells. As soon as the shells overlap at all, you can no longer treat the charge as a single point, and the positively charged nuclei will repel each other. Of course that doesn't take into account the discrete nature of electrons and any quantum mechanic effects. Can you reference some info about atomic repulsion due to the atoms only "seeing" the outer electron layer? |
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//I would assume (possibly incorrectly) that on an
atomic scale, neutral atoms wouldn't attract or
repel each other until they were within the
distance of their outer electron shells.// |
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I'm not sure, but I think you're wrong. On the
other hand, you might be right. |
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I don't have a specific reference for atoms only
"seeing" eachother's electron shells - it's one of
those things I think I've always known, without
knowing how I know it. |
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//But don't most galaxies have a black hole at
their core?// Maybe. I'm not sure what happens
to charge if a black hole swallows more protons
than electrons. Can a black hole have a charge? |
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// there would be a large magnetic field// Do we
know how big a field? In particular, do we know
how much charge (in coulombs per cubic parsec or
whatever) would be needed to hold stars together
in a spiral galaxy? My guess is that the charge
*density* would be fantastically low. |
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And do we know that galaxies don't have hefty
magnetic fields associated with them? Maybe
they do, and maybe that's why they seem to have
a preferred (aligned) spin. |
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//Can a black hole have a charge?// |
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I suspect not, because if it did, that would indicate
the relative number of protons and electrons in it.
Since information can't escape from a black hole
(according to last year's scientific thinking, at least),
it would seem to be impossible for it to have a
charge—at least, one that's determined by the
matter it has swallowed up. |
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OK, so if I make a little ion gun, and use it to fire
positive ions into a black hole, while I fire the
electrons the other way, then space gains a negative
charge but the black hole doesn't gain a positive
charge? |
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Well, if we are doing theories, my own view is that we don't need any of this scientific complication. Simple half-baked logic will serve just as well. If we live in an infinite universe which seems to be expanding (which, in my book*, rather calls into doubt our concept of what infinity is) then it seems likely that it must be expanding into something. That something must, ipso facto, be bigger than infinity. It therefore stands to reason that the gravitional forces existing in something that is bigger than infinity must be able to overcome those existing in something that is only infinite in size and hence our paltry, infinite universe is forced to expand by the overwhelming attraction of the greater than inifinite gravity without...or beyond...or whatever it is out there.
*My book is 'The Princess Bride' and I don't think that that word means what you think it means. |
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//OK, so if I make a little ion gun, and use it to fire
positive ions into a black hole, while I fire the
electrons the other way, then space gains a negative
charge but the black hole doesn't gain a positive
charge?// |
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I don't know. Is that a problem? |
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//Can a black hole have a charge?// |
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We refer you to Prof. S. Hawking, where knowledge may be had. |
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//Is that a problem?// I don't know. It just seems
odd that you could create a net negative charge in
the universe by hiding all the protons in a black
hole. |
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//do we know how much charge (in coulombs per
cubic parsec or whatever) would be needed to
hold stars together in a galaxy?// |
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That's a damned good and insightful question.
Let's see. |
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OK, we could start by asking what electric charge
would be needed to create an electrostatic force
between two stars which is (say) tenfold greater
than the gravitational force between them. |
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The electrostatic force is roughly 10^39 times
greater than the gravitational force (if we're
thinking about proton-proton forces as a simple
case). Ergo, there would need to be one surplus
electron per 10^38 hydrogen atoms. |
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A sun-sized star contains about 10^57 hydrogen
atoms, so we'd need a charge of about 10^19
electrons. That's only a Coulomb of charge, or
equivalent to charging a biggish but commonplace
capacitor up to 1 volt. |
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Hang on a tick. That doesn't sound right. Where'd
I go wrong? |
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I thought that was one of those trains that goes up
the side of a mountain? |
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I'm not sure your calculations are wrong, as such. I
think your error might be in treating a gravitational
mass as physically similar to an electrostatic charge.
I just don't think it's all that easy to maintain a
surplus of that many electrons in one place for long
enough for them to have a substantial effect before
dissipating. |
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I'm not sure why I think that, though—that's just my
gut reaction. My formal physics education amounts
to roughly nil, however, so take it for what it's
worth. |
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And the idea is?.... A yo-yo Galaxy on a string of course! |
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// OK, so if I make a little ion gun, and use it to fire positive ions into a black hole, while I fire the electrons the other way, then space gains a negative charge but the black hole doesn't gain a positive charge? //
This looks very similar as the electron holes in semiconductors. |
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I really don't know where to start criticizing this idea, so I won't. |
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I've never really understood how the space
between galaxies can be stretching, while the
space within an atom -- or for that matter (pun
intended) within a solar system, isn't. Does that
mean that gravity is necessary to hold not just
matter, but space/time together? |
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In that scenario, the classic illustration of a gravity
well -- the orbiting marble depressing the fabric of
space/time -- is incorrect and certainly somehow
counter-intuitive -- space/time is not in fact
stretched in the presence of gravity -- it's
stretched in its absence. |
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//Can a black hole have a charge?// - see link. |
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First a kick to the theory: it is proposed that mass is adequate to separate charged particles (protons in, electrons out). Then that charge different is adequate to move universe bits about. It seems to me that formidable charge puissance would just keep proton and electron together in the first place. Yah, ytk said that. |
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A testament to Max's gravitas that this party has not been banished to Overbaked for being theory. So I will sidle up to the keg! I am still fond of my extraplanar explanation for dark matter, which I rambled about in the linked Kata/Ana idea; the most relevant paragraph I will paste below. If you are going to posit matter with weird properties, the property of being extraplanar is not that weird. |
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harks back to a discussion elsewhere about "dark matter/ |
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I was getting excited about thinking about this today. Imagine not some funky 4D sphere but normal 3D objects, each in their own 3D planes. OK, for illustration instead consider a series of flatland planes stacked like shelves. Objects on different planes at some 2D distance from each other attract each other because most of the vector is the 2d distance. Objects in different planes but at no 2D distance (right on top of each other) exert no gravity on each other. One could gravitationally detect extraplanar objects at a distance but not close. That is just like dark matter. |
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Now is where my physics gets sketchy. Gravity between planes would not obey the inverse square law because the extraplanar vector component is subtracted. Objects in various planes gravitationally attracting each other would still "orbit" one another but it is not clear to me how those orbits would behave: a stack of flatland shelves would be predictable, but what if some flatland planes are perpendicular to each other, or they wrinkle on 3D space. One could have one flatlander be in the same 2D location as two extraplanar others, who themselves were far distant from each other on their own plane which they perceive as flat but is actually very wrinkly in 3D. |
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It seems like 4D objects as dark matter should be modelable and testable.
— bungston, Jun 05 2011
[edit, delete] |
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Hey, who's accusing me of having gravitas?? |
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//I'm not sure your calculations are wrong, as
such. I think your error might be in treating a
gravitational mass as physically similar to an
electrostatic charge.// I'm not disagreeing, but I
don't see the hole in the logic. The electrostatic
force between two charged particles is 10^39
times greater than the gravitational force
between two protons. |
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Ergo, if we add one electron to a star for every
10^38 hydrogen atoms it contains (and one proton
to another star for every 10^38 hydrogen atoms
_it_ contains), we will create an electrostatic
attraction between them which is 10 times
greater than their gravitational attraction. And
that amount of charge, for a typical star, is only
10^19 electrons (or protons), and hence is one
coulomb of charge. I don't see the error. |
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On the other hand, I do recall that if you put a
charge across two plates and then move them
apart, the voltage between the plates increases.
So perhaps that small amount of charge, between
two stars a light year apart, would entail some
truly bizarrely high voltage. |
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Okay, but here's the problem: |
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So, you've pumped the star full of extra electrons.
What's holding those electrons onto the star?
Gravity? Okay, but all of those electrons are
pushing away from each other with a force that's
10^39 times as powerful as gravity. |
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All of the electrons push away from each other, and
away from the star, and end up floating off into
space. Ergo, it's virtually impossible to maintain a
surplus of electrons in a star for any length of time. |
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Yeah, that sounds about right. Ah well. |
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Or is it? Might not the “natural state” of such electrons
be to settle into a “shell” orbiting the star, far away
enough that the electrons are distributed so sparsely
that the net outward force resulting from the electrons
interacting with each other is counteracted by the
gravitational pull of the star? |
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Is such a thing even possible? Or would the electrons
simply expand continuously outward? Perhaps the force
of the electrons on the direct opposite side of the star is
always greater than the pull of gravity, regardless of
distance. Or perhaps the distance is so great that
another star's gravitational pull influences the electrons
before they have a chance to settle. |
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I agree that when you add too many electrons (or protons) to a star, it will have an overall repulsion to them. However if you cut that number down, you can reach an equilibrium point where the particles are neither attracted nor repelled. For the positive star, that would be 1 proton per 10^39 hydrogen. For the star with the extra electrons, the star must be many orders of magnitude larger to hold the opposite charge. That might be on the order of 10^43 hydrogen atoms per electron, but I don't trust my source on that one. |
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You could never have a stable situation with two stars exactly at this equilibrium point because charged particles with no net attraction to its "home" star would be attracted to the distant star with the opposite charge. However, once a few charged particles had exchanged, it would stabilize. There would only need to be a small net attraction to the local star since the force drops off quickly with distance. |
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This of course doesn't give you 10x the attraction between those two stars. Actually I think it only increases the attraction by a factor of 10^39/10^43 since for this to balance, we had to increase in size of one of the stars by that factor before separating the charge. |
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I think it's clear that this idea was posted by
someone who has not thought adequately about
matters. |
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It does, however, raise another question: does the
Universe have a net charge? |
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Another question this brings to mind: If you bombard a black hole with protons to give it a positive charge, it should be possible for a proton traveling at high speed to cross the event horizon and exit again, essentially creating a secondary "proton event horizon" inside the normal event horizon. If you add enough protons you could reach the point where protons are no longer attracted at all to the black hole. Of course you’d never quite get to that state because as you get close the highest velocity protons from inside the black hole will be able to escape, so you’d reach an equilibrium where the number of protons escaping matches the number you are adding. |
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//does the Universe have a net charge?// |
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I'm not sure the Universe even has a net, so it would
be unethical to charge for it. |
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Seriously, though: The answer would seem to hinge on
whether there is some process for creating or destroying a
proton or an electron without also creating or destroying an
oppositely charged particle. As far as I can tell, there is
not. Electrons can be annihilated by collision with a
positron, but that still leaves a net charge of zero.
Likewise with protons and antiprotons. Now, a proton can
apparently be broken up into quark-gluon plasma, but that
doesn't seem to affect its net charge. |
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So, if every charged particle had to be created at some
point, and if it's impossible to destroy or create a charged
particle without likewise affecting (or effecting) an
oppositely charged particle, then the answer would seem to
be no—the Universe is has a net neutral charge. |
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Wikipedia: "The universe appears to have no net
electric charge, and therefore gravity appears to be
the dominant interaction on cosmological length
scales. The universe also appears to have neither
net momentum nor angular momentum. The
absence of net charge and momentum would follow
from accepted physical laws (Gauss's law and the
non-divergence of the stress-energy-momentum
pseudotensor, respectively), if the universe were
finite." |
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"Hey you, you're under arrest" "For what?" "You've obviously spent too long in the sun, and your skin's turned nearly black" "Are you for real? I am black!" "Exactly - you're under arrest - Dark Charge!" |
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So sorry Max - I simply can't help myself. |
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