[Infinite Grey]

So, I’ve had a question bothering me for some time. What is the net charge of the universe? I asked this of my college physics professor, and surprisingly he told me that his best estimate was that that the universe held a negative charge. What!? What happened to conservation of charge? Looking at the universe as a system with the assumption that there is nothing outside of it would imply that (due to the law of charge conservation) the net charge should be zero. Is my physics professor right? If he is, what does that imply about our universe?

[Moriarty]

Curious. Are you certain he was discussing the entire universe and not some ionized pockets of this or that?

Next time you see him, ask him how he figured this out. As a bonus question, ask him why the Universe isn't exploding if it has a net electrical charge.

[dijitalrayne]

I don't have any good theoretical answer to this. One might suspect that it would be neutral because we have yet to observe any reaction/process that violates conservation of charge. I wouldn't be surprised if pockets were ionized. One would expect there to be a positive/negative charge symmetry due to a lack of symmetry-breaking things, but one might also expect the same of matter/antimatter, and yet here we are.

[Vagrant]

I think the universe is net acidic, but the reason for that is hydrogen is so abundant. >.>

Totally random thought, my bad.

[thegnat]

	Originally Posted by Vagrant To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.
	I think the universe is net acidic, but the reason for that is hydrogen is so abundant. >.> Totally random thought, my bad.

If it's net acidic, then do you think it would correlate to charge in any fashion?

[Reon]

I have no evidence to back this up, but shouldn't the net charge of the Universe equal zero? To avoid constant incessant reactions with any outside systems?

[LaoTzu]

There does need to be balance, so I would also assume 0. However, This is more a theological than scientific observation.

[thod]

Why should the net charge of the universe be zero?

What is being argued is elegance, that symmetrical systems are more elegant than ones that are not, and thus it must be true. It was once thought that planets had perfectly circular orbits due to the same reasoning. Yet we know that the universe was not symmetrical, we were left with more matter than anti-matter for example. We have particles that carry mass but non that carry anti-mass. So why not have more carriers of negative charge than positive?, its simply what was created or what was left over. I simply don't know enough about quarks to tell you the fundamental carriers of charge.

Even if it was created equal, it doesn't mean it would stay that way. Suppose you have a pair produced by quantum fluctuation on a black hole boundary. One falls in, removing it and its information from the universe, the other escapes, adding its charge to the universe.

[JohnDoe]

Any nontrivial large scale charge imbalance in the universe would create forces that would be observable in large scale galaxy surveys. In particular because the electromagnetic force is dramatically larger then the gravitational one, any such imbalances would be very, very obvious and very very strong. Given we don't see any very very strong forces in large scale galaxy surveys, it stands to reason that there are no large scale charge gradients in the universe.

Edit: If however, there was a small (assume sufficiently small to not be observable) minor charge imbalance, I'm hesitant to say if there would be any observational issues provided such an imbalance was uniformly distributed. It would, however, present a major theoretical issue. In particular U(1) as a gauge invariance is pretty much built in into all current quantum field theories, so somehow you have to create this imbalance without breaking existing quantum field theories, and I don't know how to do that. I'm tempted to say it is very, very, very implausible that the imbalance is so small as to be just unobservable, yet still exist, and furthermore the mechanism that produces such a charge would have to not effect particle physics, which has very very very strong constraints on conservation of electric charge. The precise fine tuning of such a situation makes the odds of a nonzero charge essentially 0.

[Vagrant]

	Originally Posted by thegnat To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.
	If it's net acidic, then do you think it would correlate to charge in any fashion?

Well, chemically it should hold a net positive charge, as the lightest elements (hydrogen, helium, lithium, etc) are the most abundant elements, and are either neutral or positive. And yes, chemicals do have a bearing on electric charges (due to electrons).

That's only chemically speaking though. I'm not experienced enough in the electronics of the various forces of the universe to really say for the rest.

[thegnat]

Originally Posted by Vagrant To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

Well, chemically it should hold a net positive charge, as the lightest elements (hydrogen, helium, lithium, etc) are the most abundant elements, and are either neutral or positive. And yes, chemicals do have a bearing on electric charges (due to electrons). That's only chemically speaking though. I'm not experienced enough in the electronics of the various forces of the universe to really say for the rest.

I would agree with you...with acidity helping to yield a positive charge except in the fact that when something's deprotonated to form a base, it becomes negative. Thus the net charge of the H+ A- pair is zero (in a theoretical acid HA). Unless of course you deprotonate with something that accepts the hydrogen which in turn causes the new compound to be either neutral or positive. Then you leave the base of the acid (the "A-") negative. I'm not exactly certain whether you can say net acidity will absolutely yield a net positive charge.

Helium is neutral and inert.

Lithium, although positive is reactive (Li + H2O -> H2 + LiOH (unbalanced)). And water's not exactly a compound that isn't abundant.

If I knew what form every element was most commonly in, perhaps I could get a better feel for net charge. Unless I'm just missing something which I may be.

I suppose you probably have pure hydrogen in space...but then again it's probably H2...neutral. Helium...neutral. Other elements in space? I do not know abundancies.

[Vagrant]

Originally Posted by thegnat To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

I would agree with you...with acidity helping to yield a positive charge except in the fact that when something's deprotonated to form a base, it becomes negative. Thus the net charge of the H+ A- pair is zero (in a theoretical acid HA). Unless of course you deprotonate with something that accepts the hydrogen which in turn causes the new compound to be either neutral or positive. Then you leave the base of the acid (the "A-") negative. I'm not exactly certain whether you can say net acidity will absolutely yield a net positive charge. Helium is neutral and inert. Lithium, although positive is reactive (Li + H2O -> H2 + LiOH (unbalanced)). And water's not exactly a compound that isn't abundant. If I knew what form every element was most commonly in, perhaps I could get a better feel for net charge. Unless I'm just missing something which I may be. I suppose you probably have pure hydrogen in space...but then again it's probably H2...neutral. Helium...neutral. Other elements in space? I do not know abundancies.

Of course, I'm not speaking about reactions. LiOH is rarely found in nature as it is such a strong base. Pure lithium metal (or sodium metal) in space, however, is believable, as pure lithium's problem on Earth is the abundance of water.

I bet it also wouldn't be too surprising to find unpartnered hydrogen atoms floating around in space, seeing as the main reason they combine to hydrogen gas is the reactivity of free radicals. Without the pressure of an atmosphere (and almost never bumping into any other molecules), they can float around without reacting.

[jndiii]

	Originally Posted by thod To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.
	Even if it was created equal, it doesn't mean it would stay that way. Suppose you have a pair produced by quantum fluctuation on a black hole boundary. One falls in, removing it and its information from the universe, the other escapes, adding its charge to the universe.

Sorry, it doesn't work that way. A black hole can have a charge.





jndiii added to this post, 13 minutes and 30 seconds later...

Most of the comments here ignore the fact that while the ions would have various net charges (mostly positive), the electrons didn't just disappear. If you can prove that charge isn't conserved, you'll get a Nobel prize in physics: it would be a very cool discovery.

The observable universe appears to be made mostly of plasma: electrons and ions, with all sorts of funky magnetic fields moving them around in cool ways. Any macroscopic section of the universe will have, more or less, zero net charge, because the plasmas instantly react to any nonuniform charge distribution. Even if we assume the most radical of inflationary theories, the net charge of any given section will remain very close to zero.

All of that said, it's entirely possible for the universe to have a net charge, positive or negative. I'm not sure what degree it would contribute to its expansion, especially if it's a small net charge. The net charge would have no effect on local physics, however. (An homogeneous, isotropic distribution of that extra charge would exert no net local force except for expansion.)

[JohnDoe]

	Originally Posted by jndiii To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.
	All of that said, it's entirely possible for the universe to have a net charge, positive or negative. I'm not sure what degree it would contribute to its expansion, especially if it's a small net charge. The net charge would have no effect on local physics, however. (An homogeneous, isotropic distribution of that extra charge would exert no net local force except for expansion.)

No its not just possible. A net charge would be visible on large scale galaxy surveys unless it was very very very small. And you need a mechanism to create this net charge without breaking current theories of how matter is created. You can't just will random stuff into being without a theoretical explanation. This would actually be a really really big theoretical deal if there was an excess charge.

[Latro]

Originally Posted by Vagrant To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

Of course, I'm not speaking about reactions. LiOH is rarely found in nature as it is such a strong base. Pure lithium metal (or sodium metal) in space, however, is believable, as pure lithium's problem on Earth is the abundance of water. I bet it also wouldn't be too surprising to find unpartnered hydrogen atoms floating around in space, seeing as the main reason they combine to hydrogen gas is the reactivity of free radicals. Without the pressure of an atmosphere (and almost never bumping into any other molecules), they can float around without reacting.

OK, lemme put it this way:
Ignoring nuclear reactions for a moment, suppose you begin the universe with x protons, y neutrons, and x electrons, and suppose no other matter exists. Now suppose those protons and neutrons fuse to form the nuclei of the elements with which we are familiar now (we're imagining supernovae happening here as well), and that the electrostatic force then proceeds to convert the nuclei and free electrons into atoms. Now that we're in this state, it is not possible for Li+, Na+, H+, etc. to build up without either liberated electrons or anions also building up. That is to say, ionization reactions of hydrogen and the light metals could not cause a buildup of net charge in the universe. Having a buildup of net charge would require that the SUBATOMIC particles be created in an imbalanced fashion. Discussing that requires some discussion of things like quark physics about which I have only a minor understanding.

[JohnDoe]

Originally Posted by Latro To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

OK, lemme put it this way: Ignoring nuclear reactions for a moment, suppose you begin the universe with x protons, y neutrons, and x electrons, and suppose no other matter exists. Now suppose those protons and neutrons fuse to form the nuclei of the elements with which we are familiar now (we're imaging supernovae happening here as well), and that the electrostatic force then proceeds to convert the nuclei and free electrons into atoms. Now that we're in this state, it is not possible for Li+, Na+, H+, etc. to build up without either liberated electrons or anions also building up. That is to say, ionization reactions of hydrogen and the light metals could not cause a buildup of net charge in the universe. Having a buildup of net charge would require that the SUBATOMIC particles be created in an imbalanced fashion. Discussing that requires some discussion of things like quark physics about which I have only a minor understanding.

Right. Production of a net charge would have to be a particle physics issue, not a chemistry issue. You could create net pockets of charge using chemistry, but these would quickly dissipate because of the strength of the electric force.

[jndiii]

	Originally Posted by JohnDoe To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.
	No its not just possible. A net charge would be visible on large scale galaxy surveys unless it was very very very small.

In other words, it's possible. Personally, I believe it's zero, just the same as I believe the cosmological constant is zero, though it could possibly be very very small.

	Originally Posted by JohnDoe To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.
	And you need a mechanism to create this net charge without breaking current theories of how matter is created. You can't just will random stuff into being without a theoretical explanation. This would actually be a really really big theoretical deal if there was an excess charge.

There is tremendous hubris in any "theory of how matter is created." It's not testable, it's not falsifiable. At best it can be consistent with known theories of particle physics and General Relativity, and beyond that it is merely "thumb-sucking science."

Sorry, I'm a bit biased about cosmological theories, superstrings, and TOEs in general. (This is the stuff that fascinated me, back in the day. As you might be able to tell, I came away disillusioned.) I see such as useful for research and developing tools to analyze, but I don't expect any concrete results from them. In this instance, a theory that assumes a net positive charge, and predicts a result that is falsified by observations, that disproves the theory as a whole, but not the hypothesis of a net positive charge, per se.

To concede part of your main point, it would take a major tour de force to convince the theoretical community that there is indeed a net charge one way or the other.

[JohnDoe]

Originally Posted by jndiii To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

In other words, it's possible. Personally, I believe it's zero, just the same as I believe the cosmological constant is zero, though it could possibly be very very small. There is tremendous hubris in any "theory of how matter is created." It's not testable, it's not falsifiable. At best it can be consistent with known theories of particle physics and General Relativity, and beyond that it is merely "thumb-sucking science." Sorry, I'm a bit biased about cosmological theories, superstrings, and TOEs in general. (This is the stuff that fascinated me, back in the day. As you might be able to tell, I came away disillusioned.) I see such as useful for research and developing tools to analyze, but I don't expect any concrete results from them. In this instance, a theory that assumes a net positive charge, and predicts a result that is falsified by observations, that disproves the theory as a whole, but not the hypothesis of a net positive charge, per se. To concede part of your main point, it would take a major tour de force to convince the theoretical community that there is indeed a net charge one way or the other.

Matter creation is quite testable, its what we have particle accelerators for. Superstrings, cosmological theories, and TOE's have absolutely nothing to do with simple quantum field theories which are mostly understood. But it is testable. Because any method that would allow a net charge to develop should produce effects in particle physics that can be studied.

[jndiii]

	Originally Posted by JohnDoe To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.
	Matter creation is quite testable, its what we have particle accelerators for. Superstrings, cosmological theories, and TOE's have absolutely nothing to do with simple quantum field theories which are mostly understood. But it is testable. Because any method that would allow a net charge to develop should produce effects in particle physics that can be studied.

You're referring to energy-mass conversion in a controlled setting, not the initial boundary conditions of the Big Bang. The topic is the net charge of the universe, not the net charge of the particle accelerator. As I originally noted, discovering a true violation of charge conservation would be a major event, and yes that is all testable.

On a cosmological scale, we actually don't know the original boundary conditions. We can guess and surmise, and we're doing pretty good to have found evidence of a "beginning" of the universe, and apply our current highly-detailed knowledge of particle physics to come up with likely scenarios of the first few minutes. Eventually, however, we end up at a point where there's a big, giant question mark.

You're implicitly assuming that the initial net charge of the universe was zero, and therefore conclude, due to conservation of charge, that it must still be zero. I'm not assuming that the initial net charge is zero. There are some major asymmetries of the observable universe, such as a near absence of anti-matter; it is not unreasonable to suppose a mild excess of charge too small to be measured. Again, my opinion is that such is not the case, but the term I used was "possible".





jndiii added to this post, 11 minutes and 3 seconds later...

Now here's an interesting take my intuition just popped into my head - an extra electron or three in the initial conditions of the universe might be all it would take to "seed" the universe with matter instead of anti-matter, where an extra few positrons would have seeded it with anti-matter, and a perfect balance of charged particles would have been unseeded and remained a sea of photons and virtual positron/electron pairs (no matter ever generated, always a radiative universe). ... Anyway, that's just pure fun speculation on my part, not a serious proposal in which I am interested in defending.

[JohnDoe]

There is no good reason for an antimatter/matter asymmetry to behave differently for leptons and baryons, unless your specifically trying to create a net charge. Now your question essentially amounts to are there particles in the universe that were not created by baryiogenis and leptogensis and the answer is .. I don't know. If it was a boundary condition, it should be visible on the CMB, so I don't think you could find a way to rig such a thing up.

[SirJac]

I'd venture that even if there was some net negative charge on the universe, it wouldn't have any influence we can measure.

If we appoximate the universe as a sphere of infinite size and give it some negative charge with equal distribution and let it play out over several billion years, what would happen? I propose that the universe can be also approximated as being conductive, as the time scale and vast amounts of empty space would allow for generally free movement of excess electrons.

On smaller scales, we see that if we give a condutive sphere a charge with equal distribution the charge accumulates at the surface of the sphere nerely instantly due to mutual repulsion. Give that the universe is infinite and there is no surface to accumulate on, instead excess charged particles would simply be found ever accelerating at the farthest reaches, creating an outer shell around the rest of the matter in the universe.

Now, applys gauss' law we see that by putting a imaginary sphere between the charged shell and the rest of the matter in the universe, the net electric feild within the sphere (which encompasses the entire observable universe) is completely unaffected by the excess charged partcles.

As such, even if there was a net charge on the universe when it was first created the entire obervable universe would have no net charge and no net electric feild to measure.

[Infinite Grey]

Originally Posted by SirJac To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

I'd venture that even if there was some net negative charge on the universe, it wouldn't have any influence we can measure. If we appoximate the universe as a sphere of infinite size and give it some negative charge with equal distribution and let it play out over several billion years, what would happen? I propose that the universe can be also approximated as being conductive, as the time scale and vast amounts of empty space would allow for generally free movement of excess electrons. On smaller scales, we see that if we give a condutive sphere a charge with equal distribution the charge accumulates at the surface of the sphere nerely instantly due to mutual repulsion. Give that the universe is infinite and there is no surface to accumulate on, instead excess charged particles would simply be found ever accelerating at the farthest reaches, creating an outer shell around the rest of the matter in the universe. Now, applys gauss' law we see that by putting a imaginary sphere between the charged shell and the rest of the matter in the universe, the net electric feild within the sphere (which encompasses the entire observable universe) is completely unaffected by the excess charged partcles. As such, even if there was a net charge on the universe when it was first created the entire obervable universe would have no net charge and no net electric feild to measure.

I like this answer very much. I emailed my old Physics professor, and I'll be sure to leave a comment of his reply when he is free enough to return my email.

[DewFuel]

Originally Posted by thegnat To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

I would agree with you...with acidity helping to yield a positive charge except in the fact that when something's deprotonated to form a base, it becomes negative. Thus the net charge of the H+ A- pair is zero (in a theoretical acid HA). Unless of course you deprotonate with something that accepts the hydrogen which in turn causes the new compound to be either neutral or positive. Then you leave the base of the acid (the "A-") negative. I'm not exactly certain whether you can say net acidity will absolutely yield a net positive charge. Helium is neutral and inert. Lithium, although positive is reactive (Li + H2O -> H2 + LiOH (unbalanced)). And water's not exactly a compound that isn't abundant. If I knew what form every element was most commonly in, perhaps I could get a better feel for net charge. Unless I'm just missing something which I may be. I suppose you probably have pure hydrogen in space...but then again it's probably H2...neutral. Helium...neutral. Other elements in space? I do not know abundancies.

Interstellar elements don't really follow the rules that are found on earth. a lot of the events that created elements are accompanied without capture of electrons (since the density of these gases is extremely low, the probability of capturing an electron is also low.) but as far as hydrogen goes, most of the stuff found is charge neutral. Helium might behave funny because it has less propensity to acquire electrons than hydrogen, and it is less abundant, so i would imagine there is a larger percentage of charged helium in interstellar medium.

But all this is kind of moot because we're still talking about chemical reactions, and if we are in this realm, then everything must be charge balanced.

Any nuclear reaction, chemical reaction, or whatever you can think of requires fundamentally conservation of charge.

What we have to dig at is the creation of these particles:

If there were some asymmetry during the creation of matter (the initial moments after the big bang, if you subscribe to that theory). If we limit ourselves to strictly electrons and protons, and ignore their antiparticle creation, then it should be fairly evident that electrons would require less energetic photons to be created. The temperature and density of a photonic gas would have to be much less for the production of electrons. So if I were to guess, the net charge of the universe would have to be negative.

[Azel]

The universe has no net electric charge.

[DewFuel]

just talked to my professor, it seems particle creation is more complicated than at first glance...