Gravity or Electromagnetism? Which will win?

[Zeuzzz]

It depends on which scales your talking about. For the planetary scale gravity is dominant, and its assumed that gravity remains dominant for larger scales, an assumption that is very hard to prove. The structure of objects on larger scales certainly implies that an exclusively attractive field (gravity) has no significant role to play. Large scale jets, galaxies, and general non circular objects are extremely hard to explain with gravity, unless your happy to invent a ton of dark matter/energy to shape the field to your desired morphology. This is not true for the scale of planets and stars, which are circular, and so are seemingly dominated by gravity. For smaller objects we know for sure that EM forces reign supreme, even over great distances, thus why the properties of dusty plasmas has been getting so much attention recently. And the various complex properties of plasma in space may enable long range EM forces/pinches/instabilities to account for some large scale phenomenon, though this is hotly disputed by most.

The recent experiments that attempt to keep a spacecraft in orbit via electrodynamics are very interesting. So far they have not been sucessful, as they are not utilizing a plasma double layer which would allow the charge to stay on the spacecraft and prevent discharge, but it certainly looks like a promising prospect for the future.

http://arxiv.org/abs/0805.3332

Experimental Study of a Lorentz Actuated Orbit

This experimental study investigates a new technique to keep a satellite in orbit utilizing electrodynamics. The technique consists of establishing a charge on a satellite such that the body's motion through a planetary magnetic field induces acceleration via the Lorentz force. In order to find the relationship between capacitance and power required to balance incident plasma current, various objects were tested in high vacuum, plasma, and Xenon gas to determine their ability to hold charge. Radioactive material (Am-241) and pyroelectric crystals were tested as a candidate power source for charging the objects. Microscopic arcing was observed at voltages as low as -300 V. This arcing caused solder to explode off of the object. Insulating the object allowed the charge to remain on the object longer, while in the plasma, and also eliminated the arcing. However, this insulation does not allow a net charge to reside on the surface of the spacecraft.

And heres a brief press release outlining some of the idea and the results so far; http://arxivblog.com/?p=432

Other groups have noticed that this inherent property of plasma to separate into double layers and create large charge separation, which could potentially be used in various space propulsion devices. Heres one; Electric Double Layer is Secret Behind Revolutionary Space Thruster, but creating these stable double layer devices in practise seems to prove a lot harder than nature seems to find creating them in space plasma.

An electric double layer is a local region in a plasma which can sustain a potential difference, much like a cliff of potential (like a riverwaterfall) that can energise charged particles falling through it. These double layers are rather exotic objects that can only be described by resorting to non-linear physics. Apart from being an interesting phenomenon for space plasma physics, the ions accelerated by a double layer can be used for thrust in a space craft. Scientists at the ANU are currently building a prototype of the Helicon Double Layer Thruster (HDLT) which will be tested at the ESA (European Space Agency) in Europe.

 

[sol invictus]

It depends on which scales your talking about. For the planetary scale gravity is dominant, and its assumed that gravity remains dominant for larger scales, an assumption that is very hard to prove. The structure of objects on larger scales certainly implies that an exclusively attractive field (gravity) has no significant role to play. Large scale jets, galaxies, and general non circular objects are extremely hard to explain with gravity, unless your happy to invent a ton of dark matter/energy to shape the field to your desired morphology. This is not true for the scale of planets and stars, which are circular, and so are seemingly dominated by gravity.

More of your gibberish. I particularly like this: "This is not true for the scale of planets and stars, which are circular, and so are seemingly dominated by gravity."

Where do you get this stuff?

 

[Ziggurat]

If the mass density is high enough then collapse is inevitable, but are you sure you can get it high enough?

Actually, it's not simply density. Pick any density you want, and you'll get a black hole if you make it large enough (although if you pick a low enough density, the fact that the universe isn't flat starts to matter).

do you think you could make a black hole out of just electrons?

I don't think there's anything in the universe which can force enough electrons together, but if you could, you would get a black hole.

or would the energy required to get the density high enough result in...

No. Charge is conserved, so it's not like quark separation: creating new particles won't lower the energy. And the energy of repulsion will contribute to the gravity of the collection.

 

[Zeuzzz]

More of your gibberish. I particularly like this: "This is not true for the scale of planets and stars, which are circular, and so are seemingly dominated by gravity."

Where do you get this stuff?

How can a field that has no repulsive component create an object of substantial mass that is not a spherical shape? Can you point me to an object of ~solar/planetary size of substantial mass that is any shape other than spherical? Any triangular planets you know of? Toroidal?

Its quite clear that at solar/planetary scales gravity dominates. This is evidenced in our own Solar System in which gravitational dynamics dominate even with the observed effects of solar wind, coronal mass ejections, auroras, comet tails, etc. The plasma in our Sun is stabilized by gravitational forces, even though plasma effects are very active within the Sun itself. When you get up to galactic scales, the morphology of objects do not seem to obey Newtons law so much. Thus why various Dark things are invented to explain the various anomalies, and balance various forces. Its really quite simple Sol. "it is highly likely that the hierarchy of structures in the universe, the lab, earth, solar system, galactic, cosmic does not stop at the laws that we use in the solar system, but requires a corresponding hierarchy of theories."

http://www.cosmology.info/2005conference/wps/gallo_1.pdf

The rotational dynamics of our Solar System fits gravitational theory very well. No additional matter or forces are significant.
However, the measured rotational dynamics of Spiral Galaxies do NOT fit gravitational theory alone. Two different solutions have been presented to explain this gross distortion from gravitational dynamics: (1) Dark Matter , and (2) ElectroMagnetic Plasma Effects. .

 

[ponderingturtle]

How can a field that has no repulsive component create an object of substantial mass that is not a spherical shape? Can you point me to an object of ~solar/planetary size of substantial mass that is any shape other than spherical? Any triangular planets you know of? Cubes?

Well one spherical makes no sense, as a orbit will be 2 dimensional not 3. Also you need to look at science that predates the theory of universal gravitation, namely that the orbits are not circles but elipses, discovered by Kepler in around 1605.

 

[Zeuzzz]

Well one spherical makes no sense, as a orbit will be 2 dimensional not 3. Also you need to look at science that predates the theory of universal gravitation, namely that the orbits are not circles but elipses, discovered by Kepler in around 1605.

I was not talking about orbits. I was talking about the shape of planetary/solar physical objects. Which, at this scale, are always spherical. (actually, there are some enigmatic exceptions: http://www.holoscience.com/news.php?article=x50hfzxa "Although astronomers already knew that Achernar spins at least 225 kilometers per second, they were flat-out astonished by their newest observations. The squashed star is more than 1.5 times as wide as it is tall.")

 

[DeiRenDopa]

Question for robinson: what is "Electromagnetism(EM)" (as in the OP of this thread)?

How does the "EM" in the OP relate to contemporary physics?

To what extent do you intend this thread to be a discussion that is science-based?

 

[ponderingturtle]

I was not talking about orbits. I was talking about the shape of planetary/solar physical objects. Which, at this scale, are always spherical. (actually, there are some enigmatic exceptions: http://www.holoscience.com/news.php?article=x50hfzxa "Although astronomers already knew that Achernar spins at least 225 kilometers per second, they were flat-out astonished by their newest observations. The squashed star is more than 1.5 times as wide as it is tall.")

Also the earth is an oblate spheriod, not a perfect sphere.

See Saturn, its polar radius is 54,364 km, its equitorial radius is 60,268 km.

 

[Ziggurat]

How can a field that has no repulsive component create an object of substantial mass that is not a spherical shape? Can you point me to an object of ~solar/planetary size of substantial mass that is any shape other than spherical? Any triangular planets you know of? Toroidal?

The rings of Saturn are toroidal. So is the asteroid belt. And the solar system itself is not spherical at all: it's planar. The obvious answer to your question is angular momentum. Angular momentum is what keeps them in a flattened configuration. Kind of like, you know, the galaxy.

 

[Zeuzzz]

The rings of Saturn are toroidal. So is the asteroid belt.

with all due respect, the rings of saturn, or the asteroid belt, are not really on the scale of the planets, which was the specific scale I was referring to, ie, where the mass is sufficient to nearly always create a (roughly) spherical shape. Meteors are generally not spherical as gravity is not strong enough to make them so. But larger scale objects generally are, that is, until you get to far larger and massive structures where this observation seems to break down somewhat.

And the solar system itself is not spherical at all: it's planar. The obvious answer to your question is angular momentum. Angular momentum is what keeps them in a flattened configuration. Kind of like, you know, the galaxy.

No quarms here.

 

[Ziggurat]

with all due respect, the rings of saturn, or the asteroid belt, are not really on the scale of the planets, which was the specific scale I was referring to, ie, where the mass is sufficient to nearly always create a (roughly) spherical shape.

That's what you get if a large enough mass has a low enough angular momentum and is sufficiently dense. Take away any of those criteria, though, and you don't end up with a spherical body, even if it's very massive.

No quarms here.

Do you mean "qualms"? Because I've never heard of "quarms" before.

 

[Reality Check]

How can a field that has no repulsive component create an object of substantial mass that is not a spherical shape? Can you point me to an object of ~solar/planetary size of substantial mass that is any shape other than spherical? Any triangular planets you know of? Toroidal?

Its quite clear that at solar/planetary scales gravity dominates. This is evidenced in our own Solar System in which gravitational dynamics dominate even with the observed effects of solar wind, coronal mass ejections, auroras, comet tails, etc. The plasma in our Sun is stabilized by gravitational forces, even though plasma effects are very active within the Sun itself. When you get up to galactic scales, the morphology of objects do not seem to obey Newtons law so much. Thus why various Dark things are invented to explain the various anomalies, and balance various forces. Its really quite simple Sol. "it is highly likely that the hierarchy of structures in the universe, the lab, earth, solar system, galactic, cosmic does not stop at the laws that we use in the solar system, but requires a corresponding hierarchy of theories."

http://www.cosmology.info/2005conference/wps/gallo_1.pdf

Hi Zeuzzz, "various Dark things" implies a lot of dark things. There are just two - dark matter and dark energy. The only one that has to do with gravity is dark matter (dark energy is to do with the expansion of the universe). As you must know by now (or choose to ignore) dark matter has actually been observed. Therefore we find that Newton's law holds at large scales when we account for all of the matter involved.

A local observation that supports the existence of dark matter: Dwarf galaxies in the Local Group are 400 times more massive than their visible matter.

You should also note that the quote in your post also applies to electromagnetism, i.e. the "corresponding hierarchy of theories" is needed for both EM and gravity.

 

[Zeuzzz]

That's what you get if a large enough mass has a low enough angular momentum and is sufficiently dense. Take away any of those criteria, though, and you don't end up with a spherical body, even if it's very massive.

Yeah, if your being precise. Though it may make more sense to say that's what you get if a small enough volume is sufficiently dense and has low enough angular momentum. But that pretty much means the same thing.

Do you mean "qualms"? Because I've never heard of "quarms" before.

I have an tendency to spell things how they sound as opposed to how they should be spelt, If i cant hear a silent letter it just doesn't tend to enter my head.

Or to put it another way, I'm crap at spelling.

 

[NoisyAstronomer]

How can a field that has no repulsive component create an object of substantial mass that is not a spherical shape? ...

When you get up to galactic scales, the morphology of objects do not seem to obey Newtons law so much. Thus why various Dark things are invented to explain the various anomalies, and balance various forces.

They obey Newton's laws quite well, until you realize that an extra component IS needed to describe the motions of stars and gas as your go further out in spirals. This idea of dark matter was met with great skepticism when it was first introduced, and rightly so. But decades of research have shown dark matter to be a real thing. My favorite being the Bullet Cluster, which shows, using gravitational lensing, where most of the mass in the two interacting galaxy clusters lies. It's not with the hot gas that makes up most of the visible matter of the cluster, it's in the unseen dark matter.

Why don't large scale objects fall into a spherical shape? As another poster pointed out, conservation of angular momentum keeps rotating systems "up" in the same way that the planets have orbited the sun for billions of years. This goes for spiral galaxies, where the orbits are ordered in a plane, as well as for elliptical galaxies where the orbits are randomized.

Even these things tend towards a spherical shape and homogeneity when they are virialized. But this takes a very, very long time for most systems of these sizes and densities, though some galaxy clusters seem to be virialized.. but by now I'm way out off topic

 

[LordoftheLeftHand]

Gravity or Electromagnetism? Which will win?

I'm putting all my money on the Strong force. (Rolling dice) comeon, baby needs a new pair of shoes!

LLH

 

[Dancing David]

They obey Newton's laws quite well, until you realize that an extra component IS needed to describe the motions of stars and gas as your go further out in spirals. This idea of dark matter was met with great skepticism when it was first introduced, and rightly so. But decades of research have shown dark matter to be a real thing. My favorite being the Bullet Cluster, which shows, using gravitational lensing, where most of the mass in the two interacting galaxy clusters lies. It's not with the hot gas that makes up most of the visible matter of the cluster, it's in the unseen dark matter.

Why don't large scale objects fall into a spherical shape? As another poster pointed out, conservation of angular momentum keeps rotating systems "up" in the same way that the planets have orbited the sun for billions of years. This goes for spiral galaxies, where the orbits are ordered in a plane, as well as for elliptical galaxies where the orbits are randomized.

Even these things tend towards a spherical shape and homogeneity when they are virialized. But this takes a very, very long time for most systems of these sizes and densities, though some galaxy clusters seem to be virialized.. but by now I'm way out off topic

Welcome to the Forum!

 

[robinson]

... Its quite clear that at solar/planetary scales gravity dominates. This is evidenced in our own Solar System in which gravitational dynamics dominate even with the observed effects of solar wind, coronal mass ejections, auroras, comet tails, etc. ...

This brings us back to the central issue. In regards to large bodies, planets, asteroids, moons, comets, even space probes, gravity wins. Of course win isn't very scientific, neither is dominates. Maybe gravity is more important. It is obvious the motion of large bodies is because of gravity, as well as the very shape of objects. Well, most of them, those asteroids and the moons of Mars are not obeying, as well as comets and the like.

And if we are stuck in the old fashioned view that only objects matter (pun intended), then it is easy to say gravity is it baby. Gravity wins!

But back to the OP, which of course describes a real event, not a theoretical one, even with the errors in velocity and such, we have another situation. Small stuff doesn't seem to care as much about gravity as it does EM forces, especially magnetic fields.

Plasma, as well as hydrogen and helium, they seem to be directed by EM, and of course, EM radiation of all kinds doesn't give a hoot about gravity.

So how can we compare the two? One sucks, the other goes shooting off like crazy, and doesn't care about gravity. Much. (real near the sun, yes).

Gravity keeps large objects in orbit around the sun, but EM, mostly from the sun, sends all kinds of matter away from the sun!

Doing some quick calculations, EM causes far more mass to leave the solar system than is orbiting the sun. Rough figures, every 30,000 years, more mass leaves the solar system from EM, than the mass of the planet earth.

Don't take my word for it, you can do the math yourself. Took me about 5 minutes.

I didn't include CMEs, due to the variations with solar cycles. It would only add around 1.8 trillion tons a year, at solar maximum. So yes, it would be less than 30,000 years, but there are other factors. Very hard to calculate.

Before somebody point out that most of that mass is leaving as energy, if you discount the EM itself, the protons and electrons ejected still equal the mass of the earth every 150,000 years. And those particles are leaving at between 400 and 1,000 Kilometers a second. It wouldn't be fair to use relative mass, due to high velocity. That would dwarf our entire planetary system very quickly.

Even low ball figures show EM dominates gravity, in our local system. Much much much more mass is leaving the solar system, than is orbiting the sun. Since the earth as formed, the sun has sent something like 133,333 times the mass of the earth shooting off into space.

Even if I screwed up the calculation by an order of three magnitudes, EM still wins.



I hope somebody else does the math, because I am a little amazed it is that much. It doesn't seem right.

I would have thought maybe a few dozen planet earths of mass.

 

[robinson]

OK I am 100% sure that previous post is wrong. It is impossible.

No time to do the correct maths. It has to be far less mass than that.

 

[robinson]

3.1536 × 10¹³ solar wind each year

1.5768 × 10¹⁴ EM each year

6.6 × 10²¹ mass of earth


Math is hard.

 

[Hellbound]

1 Earth mass every 34,880,000 years.