Is gravity only magnetism in disguise?

[rigney]

Could it be that gravity is only magnetism in disguise? We know that planets, moons, asteroids, our sun and literally everything else existing throughout the universe is said to possess what we consider to be gravity. Yet, while science has found that every atom has magnetic properties, there is no evidence they posesse gravity; other than a beautifully constructed formula by Sir Isaac Newton, which I'm not going to equivocate simply because it works. But for instance, when earth began forming; were those first bits of (dust) matter, coalescing with other dust particles because of magnetism or gravity? When earth was basketball size, had gravity gained the upper hand, or was magnetism somehow still a part of the mix. Even when this planet was the size of our moon, was the controlling factor gravity or magnetism? Please, don't beat me up; just give me some feedback.

Edited September 6, 2010 by rigney

[Mr Skeptic]

Easy demonstration: lift a car with a large electromagnet. Then, try to lift a feather.

[rigney]

Easy demonstration: lift a car with a large electromagnet. Then, try to lift a feather.

 

Gotcha! But I can lift a small piece of paper with a comb that I've run through my hair a few times, but the comb won't stick to the car either. Never tried it with a small feather?

Edited September 6, 2010 by rigney

[Mr Skeptic]

That's electrostatics.

[rigney]

That's electrostatics.

 

How did I know you'd be going there? Seriously though, if gravity is actually a force in itself, what size must something be to begin exerting this force? That's why I mentioned the different stages of earths development. Does a point eventually come to where gravity is boss and an increasing size brings on an increase in force?

[John Cuthber]

IIRC the electromagnetic force is about 10^36 times bigger than the gravitational force.

Asking if one is the other in disguise is something like asking if a virus is the planet Earth in disguise.

I may have lost count of the decimal places there; but there's clearly a difference.

On the other hand, they may be different aspects of the same "unified" force.

At this point physicists start talking about wriggly bits of string so I will leave them to it.

[Mr Skeptic]

Any and every object exerts a gravitational force. It is much much weaker than the electromagnetic force.

[timo]

To fake being on-topic: No. There's no reason to assume gravity was a form of magnetism. According to mainstream physics the answer is even more strict: it isn't.

 

Actual point (off-topic but I find it worthwhile commenting on a common and in my opinion incorrect statement):

IIRC the electromagnetic force is about 10^36 times bigger than the gravitational force.

It is indeed common to throw around such ratios but I tend to deny that they make any sense outside a well-defined context. For example, a particle physicist might take the heaviest object he'll ever expect to encounter and compare the expected gravitational force (say, assuming classical gravity) to the force felt if two such objects had an electric charge of one. Without such a rather well-constrained context, I doubt that such ratios have any meaning. Or asked the other way round: What do you think it means that "the electromagnetic force is 10^36 times larger than the gravitational force"? For sun and earth, it's pretty widely acknowledged that gravity is the dominating force, for example.

[John Cuthber]

The figure quoted is generally for an electron and a proton attracting one another. (You can move the decimal point a bit by looking at the force between two protons or two electrons.)

 

If you looked at the force between all the protons in the sun and all the electrons on earth the force would still be roughly 10^36 times bigger than the gravitational force.

The difference is that the electrostatic attraction is practically cancelled out by the protons in the earth and the electrons in the sun.

 

This is, of course, another example of the difference; gravity doesn't ever seem to cancel out.

Incidentally, the reason I can pick up a book is that a relatively small amount of electromagnetic force (in my muscles) can overcome an entire planet's worth of gravity.

That's really quite a big difference.

[timo]

I was about to ask if you happen to be a chemist by chance. But I guess the "chemistry expert" sign kind of answers that. You are probably right that if your world consists of protons and electrons, a ratio of the forces can be given. It's actually pretty similar to my example of a particle physicist who also investigates a limited range of effects on a limited scale (ignoring the infamous Planck units for a second ).

In practice, relevant forces and their (relative) magnitudes depend on the phenomenon (e.g. a neutron star where relevant forces are gravity and volume-dependency of the energy levels) and also how you view it. It's perfectly fine if you think that there is a force between sun's protons and earth electrons that is countered by another force between both objects' electrons. But you can also consider the electric field caused by the sun (pretty much zero) and then look at its effect on earth and compare that to sun's gravitational field and its effect on earth (non-zero). There is not much reason to call one view correct and the other one wrong (I could argue that the field-based approach is more modern but that doesn't make the force-based view wrong).

[Mr Skeptic]

Why is gravity so weak?

Why is the electron/proton mass so small?

 

Both of those are essentially the same question.

[rigney]

My knowledge of gravity is far less than what any of you have presented. So, could someone explain to me how large this planet must have been in mass and density, to allow gravity to became the controlling factor? Or did it happen when the first two bits of dissimilar matter came together to form a bond and progress from there? I'm a firm believer in magnetism but can't understand the action of gravity other than something almost mystical. I've worked with electricity my entire life and in general know circuitry and why we use it as we do. But gravity has me stumped.