Gravity or Electromagnetism? Which will win?

[The Man]

Teehee. Best description ever.

Thanks, but it just followed from your “wrestling match” remark

Hmmm. I know this isn't what the discussion is about, but indeed gravity first acts on neutral atmoic hydrogen to make stars, it is only in the hot, pressurized interior does hydrogen ionize and the EM force become important. Then again, EM forces hold atoms together in the first place. Ack! I think the whole thing of asking "which is more important" is just trivial. But asking which is stronger in certain circumstances can be talked about. It's just complicated.

Well, some people make it even more complicated then it really is, but I don’t mean you.

Again, I'm still not sure whether we're talking about electric and magnetic fields or light.

Both, since light is basically the oscillation of an electro-magnetic field.

Hmmm... I may have heard of that before.

Probably, but lacking any significance, it is very easy to forget

 

[robinson]

Ack! I think the whole thing of asking "which is more important" is just trivial. But asking which is stronger in certain circumstances can be talked about. It's just complicated.

Indeed. It started due to the claim that at great distances, gravity "dominates", or "gravity is all that matters", or something like that.

Same for "large objects". Gravity is all that matters.

Which is why I pointed out that EM fields and ionized particles, as well as electrons, protons and plasmas, can extend at distances and power levels that make gravity a trivial matter.

A 20 light year jet of high energy plasma, or a hundred light year radio lobe, makes the gravity of the source pale by comparison.

That energetic plasmas and particles, accelerated to near light speeds are not even effected by gravity, but contained and channeled by EM fields, makes it even more absurd to try and claim gravity is all that matters.

In the original objection I pointed out a supernova going off nearby isn't going to matter much at all, from a gravitational perspective, but the Electromagnetic energies could kill us. Even at a great distance.

Of course gravity dominates for orbits of planets around stars. Maybe even for Galactic rotation. But if you buy into the dark energy thing, gravity doesn't dominate between Galaxies. Dark energy is more powerful than gravity.

Of course maybe dark energy isn't real energy, but some new force, so it might not be EM as well. Great mysteries abound.

Space, the final frontier.

 

[Tubbythin]

In the original objection I pointed out a supernova going off nearby isn't going to matter much at all, from a gravitational perspective, but the Electromagnetic energies could kill us. Even at a great distance.

In supernovae, ten times the energy given off in the form of photons is carried away by neutrinos. Neutrinos only couple to the weak force (erm, and gravity). Ergo the weak force is clearly the strongest force.

 

[The Man]

A 20 light year jet of high energy plasma, or a hundred light year radio lobe, makes the gravity of the source pale by comparison.

That energetic plasmas and particles, accelerated to near light speeds are not even effected by gravity, but contained and channeled by EM fields, makes it even more absurd to try and claim gravity is all that matters.

"gravity is all that matters"? Keep stuffing straw, but I doubt you can get that man to stand up long enough for you to knock it down.

That those "jet of high energy plasma" and "energetic plasmas and particles, accelerated to near light speeds" or Relativistic Jets can be powered by a rotating black hole still gives gravity a dominate role in such cases.

http://en.wikipedia.org/wiki/Galactic_jet

“makes the gravity of the source pale by comparison”, unless of course gravity is the source, for the power of those emissions.

 

[NoisyAstronomer]

I think maybe the "gravity dominates" argument stems from the observation that most "normal" phenomena are gravitational. The building of galaxies, clusters, stars themselves, etc. Phenomena like radio lobes of galaxies are still considered rare in the universe.

But more importantly, gravity, being the weakest of the forces, is so important to the history of the universe that we just stand around in awe at it.

 

[The Man]

I think maybe the "gravity dominates" argument stems from the observation that most "normal" phenomena are gravitational. The building of galaxies, clusters, stars themselves, etc. Phenomena like radio lobes of galaxies are still considered rare in the universe.

But more importantly, gravity, being the weakest of the forces, is so important to the history of the universe that we just stand around in awe at it.

Although the weakest force, on a scale comparison, it is the only cumulative force. Get enough charges of one kind together and they will explode from their repulsion. Counter that repulsion with opposing charges and you end up with essentially no charge, or charge neutral. Strong force, hell it’s great when you are trying to separate quarks, get them far enough apart, oops enough energy to create another quark and now you have to separate them again. Only gravity builds upon itself, get enough mass in a small enough volume and a singularity, infinities abound, including energy. The solution to oil dependence, but you might not be able to go anywhere in a black hole powered car (unless it is a contained micro black hole evaporating).

 

[Dancing David]

To other readers: what are the odds that r will offer an apology? or admit to ignorance?

I know that you two has been a fueding but the answer is won't. R. is a contrarian sceptic and often is just rattling people chains. I find that it is probably humor.

 

[robinson]

I think maybe the "gravity dominates" argument stems from the observation that most "normal" phenomena are gravitational. The building of galaxies, clusters, stars themselves, etc. Phenomena like radio lobes of galaxies are still considered rare in the universe.

It is no doubt a false dichotomy, this belief that one force dominates another. While discussing vast distances and large objects, if we go the other way, right here on the surface of the planet, EM dominates almost everything we experience, except for being stuck to the planet.

But more importantly, gravity, being the weakest of the forces, is so important to the history of the universe that we just stand around in awe at it.

That was funny. It made me realize that it is a damn good thing gravity is so weak, or the Universe would be far different than it is now. The weakness of gravity means we can live on a huge planet like ours, without much fuss.

It also led to pondering another issue. It has been said that gravity can't be blocked, or neutralized, unlike EM (talking specifically about charge only).

Large bodies tend to be mostly neutral (discounting the currents flowing in the core that produce the magnetic field, as well as the vast and powerful Van Allen belts, which are far from neutral).

But considering gravity, regarding local effects, like here on earth, the earth's gravity neutralizes the gravity of the sun, as well as the moon, and every other gravity source in the Universe. While gravity may be vast, acting at huge distances, to us, stuck firmly to a globe spinning at a thousand miles an hour (equator), or even spinning very slowly (poles), none of that gravity really matters to us. We can't even detect it, unless you count the tides, which are more of a giant wave, rather than water being pulled towards the source.

An accelerometer won't even show the effect of the moon, which is by far the most powerful local effect, from gravity.

Yes yes, we fall around the sun due to gravity, but none of that motion is measurable from our viewpoint, deep in the gravity well of our planet. In reagrds to gravity, the earth's gravity is neutralizing all the other sources in the Universe, due to our proximity.

Interesting. Neutralize is probably not the correct word, I know that. But from a practical viewpoint, nothing else matters much, in terms of gravity, here on the planet.

Aside from the moon and sun, nothing else is even close to being an issue to us, as far as gravity goes.

In a practical sense.

 

[Vorpal]

It is no doubt a false dichotomy, this belief that one force dominates another. While discussing vast distances and large objects, if we go the other way, right here on the surface of the planet, EM dominates almost everything we experience, except for being stuck to the planet.

Or we can simply say that that the significance or domination of forces is relative to the effect we're considering or focusing on. The entire premise of this thread is seemingly based on taking something inherently context-dependent and trying to force it to be an absolute statement.

But considering gravity, regarding local effects, like here on earth, the earth's gravity neutralizes the gravity of the sun, as well as the moon, and every other gravity source in the Universe.

No, it does not. We're as much in orbit around the Sun as Earth itself is. We're accelerating toward the Sun at about 1/1700 of Earth gravity, and toward the Moon at about 1/300,000 of Earth gravity.

We can't even detect it, unless you count the tides, which are more of a giant wave, rather than water being pulled towards the source.

???

An accelerometer won't even show the effect of the moon, which is by far the most powerful local effect, from gravity.

It wouldn't matter if the absolute force (in the Newtonian framework) due to either the Sun or the Moon were a thousand-fold higher. An accelerometer still wouldn't measure the force. The only things that would be measurable would be tidal forces.

Yes yes, we fall around the sun due to gravity, but none of that motion is measurable from our viewpoint, deep in the gravity well of our planet.

Right, but you seem to think that this is because of the Earth's gravity, which is just fundamentally wrong. If you throw an accelerometer in the air, it wouldn't register any acceleration while in freefall, regardless of how strong the Earth's gravitational field is.

In reagrds to gravity, the earth's gravity is neutralizing all the other sources in the Universe, due to our proximity.

It does no such thing. If you were to go into space and orbit the Sun at the same orbit as the Earth, you would still feel no acceleration, and your accelerometer would not register anything. The same is also true for any other orbit.