# Gravity and Magnetism the same?

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#### bowman316

##### Guest
You ever think if gravity and magnetism are the same force?
Every object of large mass out in space has gravity, which just pulls other objects closer to it. But if both objects are nearly the same size, they tend to orbit. which can be viewed as 2 of the same poles rejecting each other. They don't want to get too close to each other.

I know these 2 forces are similar, but maybe they are more similar than we think?

Imagine the sun being a N pole, and so are we. Or maybe we are attracted, but jupiter is holding up back in a tug of war, and jupiter is the same pole as the sun, but we are opposite poles from both.

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#### MeteorWayne

##### Guest
Absolutely not. They act in different ways.
You should really spend some time educating yourself about how gravity and magnetism work. If you do so, you will find they are in no way comparable.

For one thing, gravity always presents as an attractive force, while magnetism can attract or repel.

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#### bowman316

##### Guest
then why does the moon not crash into us, why does it stay so far away?
There has to be some sort of repeling force there.
Is it just the fact that the moon's gravity is pushing against the earths?

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#### drwayne

##### Guest
Actually, the moon, like any other objects in orbit is in fact falling towards the Earth! All the time!

It just so happens it is on a trajectory in which it's falling towards the Earth is countered by the fact
that the Earths surface is falling away from it at the same rate. No repulsive force required.

Wayne

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#### MeteorWayne

##### Guest
It is because the moon is in motion. It is in fact falling toward the earth. But the earth's surface is falling away (since it's a sphere) at exactly the same rate. That is the definition of an orbit. If the moon was standing still, the earth's gravity ould pull it in, and it would hit the atmosphere at 11.2 km/sec (about 25,000 mph). Again, that's basic high school level Newtonian/Keplerian physics. It has been understood for more than a few centuries.

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#### drwayne

##### Guest
Keep in mind that there is nothing "magic" about the moon, it is a satellite - just like Vangaurd.
It doesn't acquire new properties (repulsion) in orbit that it didn't have on Earth.

--------------------------------------------------------------------

As an entertaining tangentially related exercise for the reader, consider the following proposition.

Suppose I were to invent a way to create a "negative" mass - call in Wayneium (very dense to be sure).

If I were to release it here on Earth, what would happen, and why?

Wayne

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#### MeteorWayne

##### Guest
To follow up a bit, if the earth's gravity were not pulling on the moon, with it's motion it would fly in a straight line off into space. The earth''s gravity curves the path into an orbit.

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#### Saiph

##### Guest
I think I'll quote the Sage Douglas Adams in one of his Hitchhiker's guide to the galaxy books: "The trick to flying is to throw yourself at the ground, and miss".

That's exactly what the moon is doing. It is falling towards earth, but it's ALSO moving sideways at a high speed...so it misses. It's all about inertia.

A more appropriate analogy would be a weight on a string. Take a string, which can only pull objects. I mean, have you ever tried to push anything with a piece of twine? Doesn't do much at all! Now, tie a weight to it, and spin it around your head. The string is constantly pulling the weight towards your hand, you can actually feel that. But the weight doesn't ever reach your hand because you're spinning it about.

This string, which can only pull, is keeping the weight about your hand, and yet the weight doesn't come crashing into your hand despite, as you put it, the lack of a 'repulsive' force.

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#### bowman316

##### Guest
The moon is actually slowly getting farther away. In a million years or so, it will be really far away, and eventually get shot out into space.

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#### Mee_n_Mac

##### Guest
bowman316":32bhj3w9 said:
The moon is actually slowly getting farther away. In a million years or so, it will be really far away, and eventually get shot out into space.

No it won't. What makes you think the above ? What's happening is that the rotation of the Earth is slowing down (as it has already for the Moon). Due to conservation of angular momentum the Moon's orbit is slowing increasing in radius. When the Earth no longer rotates wrt the Moon the increase in orbit will stop. The Moon isn't going to leave Earth orbit, at least due to any predictable cause.

http://curious.astro.cornell.edu/questi ... number=124

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#### Saiph

##### Guest
granted, using that mechanism it is possible to for a satellite to leave orbit, but it won't happen with our moon.

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#### kelvinzero

##### Guest
bowman316":dwf6fx83 said:
You ever think if gravity and magnetism are the same force?
Every object of large mass out in space has gravity, which just pulls other objects closer to it. But if both objects are nearly the same size, they tend to orbit. which can be viewed as 2 of the same poles rejecting each other. They don't want to get too close to each other.

I know these 2 forces are similar, but maybe they are more similar than we think?

Imagine the sun being a N pole, and so are we. Or maybe we are attracted, but jupiter is holding up back in a tug of war, and jupiter is the same pole as the sun, but we are opposite poles from both.

Gravity does not seem to be at all like magnetism, but reputable physicsts are trying very hard to unify basic forces such as gravity, electric forces and the forces that keep protons and neutrons together to form the nucleus of an atom.

Have a look at this link: http://en.wikipedia.org/wiki/Unified_field_theory

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#### Fallingstar1971

##### Guest
drwayne":1ovnoa07 said:
Keep in mind that there is nothing "magic" about the moon, it is a satellite - just like Vangaurd.
It doesn't acquire new properties (repulsion) in orbit that it didn't have on Earth.

--------------------------------------------------------------------

As an entertaining tangentially related exercise for the reader, consider the following proposition.

Suppose I were to invent a way to create a "negative" mass - call in Wayneium (very dense to be sure).

If I were to release it here on Earth, what would happen, and why?

Wayne

Wouldnt Mass and Anti-mass mutually destroy each other? I would say that at the moment of release, Whatever the amount of "anti" or "negitive" mass would instantly destroy an equal amount of regular mass and the energy......wait a sec.....

E = MC2

E = -MC2

-E = -MC2 (Whatever you do to one side of the equal sign you have to do to the other)

errrrrrr

OK

Anti-Energy

Instead of a titanic explosion, a titanic IMPLOSION that sucked the energy out of everything (living things included)

Wow, that would be weird. You just may kill the universe.....

Star

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#### drwayne

##### Guest
No, I specifically did *not* call it anti-matter. I didn't even call it anti-mass.

This is a thought experiment that requires one to think about a couple of effects that mass (and its
"polarity") has on the motion of a mass acting under the influence of gravity.

Wayne

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#### Fallingstar1971

##### Guest
The point I was making was simple........

Negative mass as opposed to what exactly......positive mass? How would it be "negative?" Opposite charges? And would not the rest of the Universe be "positive" mass?

Or is it negative mass as in a mass measurement below zero?

In statement two, it would generate anti-gravity I think. The one instance in the Universe where opposites would NOT attract because the negative mass would push away while the positive mass would attract due to gravity.

In your "thought" experiment, gravity and anti-gravity could cancel out. So I guess if you rule out gravity, then all you have left is the electromagnetic charges of the two objects. That would cause them to move together like two oppositely charged magnetic fields. Under the right circumstances you may even produce an electrical charge like the +/- of a battery.

As far as anti-mass/anti matter, well, I guess that since things made of antimatter still have a positive mass, then yes, I misunderstood your original statement.

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#### drwayne

##### Guest
"Negative mass as opposed to what exactly......positive mass?"

Exactly. Thought experiment - mass analogy to electrical charge.

How does this impact how the mass reacts to the Earth?

Wayne

p.s. Bonus question that you might want to think about first. How does it react Wayneium react to an appled force?

W

#### williammook

##### Guest
Pick up a copy of Misner Thorne and Wheeler's GRAVITATION (big black cover with the word 'GRAVITATION' in white 1,100 pages) The book is really cool, it introduces DIRAC NOTATION - introduced back in the 40s to describe functional relationships between one tensor field and another. You have BRAKETS and the consist of BRA and KET. <| is a bra. |> is a ket. <a| is a column vector, or tensoer. |b> is a row vector, or a transpose of a tensor. You can relate the two;

<a| C |b>

This simplifies the older Einsteinian notation where you sum all the rows and columns.

The form of electromagnetic force is the same as gravitic forces. They are both inverse square laws. They are however, distinctly different in detail. One deals with moving charges and is fully described by Maxwell's equations. The other deals with moving masses and is fully described by Einstein.

Page 99 - shows that the Lorentz force is nothing like gravitational force

Page 111 shows how the electromagnetic 2-form naturally gives rise to radiation by accelerating charges.

PAge 77 shows the different ways to write the underlying math... Maxwells equations become very simple with the right notation

Think of air blowing around. Divergence measures how many flow lines there are perpendicular to the flow. Gradient is te variation of pressure along the flow line. Curl doesn't happen with blowing wind, but it does happen with Electromagnetic forces - a charge moving along a path produces a magnetic field that curls around the path.

Page 147 details Gauss' theorem and shows how Lorentz forces and gravity forces are created - but Lorentz forces are communicated via electrostatic and electromagnetic fields. Gravity forces are generated by geometric deformations of spacetime itself.

A magnetic or electric field has the same form as a gravity field. It sin't the same thing exactly, the dimensionality is not right. Its these extra dimensions that make gravity electromagnetic and electrostatic forces have different strengths. As does the weak force and strong force.

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#### ramparts

##### Guest
I'm surprised that none of the people more familiar with GR have brought up Kaluza-Klein theory so far. It's not an answer to the OP's questions (which have to do with much simpler physics), but it's an absolutely beautiful piece of work, highly interesting, and is at least what I immediately think of when the question "are gravity and [electro]magnetism the same?" is asked. So, despite it being tangential, and 3 in the morning here, I think it's interesting enough to warrant a post And possibly a thread hijack.

Einstein came up with his field equation in 1915, which in mathematical language both stunningly simple and unimaginably complex describes how the curvature of spacetime (on one side of the equation) is proportional to a given distribution of mass and energy (on the other side). A second equation takes in that spacetime curvature and lets you compute the paths that one takes in that spacetime, and voila - we're able to describe the effects of gravity in general relativity.

Now, these equations don't depend on the number of dimensions of spacetime - it's usually trivial to solve the Einstein field equation in as many dimensions as you'd like. So some fellows (including the named Kaluza and Klein) decided to imagine that there was an extra dimension of space, and solve Einstein's equations in this new 5-dimensional paradigm, with one caveat - that the laws of physics don't depend in any way on that fifth dimension (a question in itself). As an added bonus, they did so by setting the matter/energy side of the equation to 0 - in other words, taking Einstein's equation in a 5-dimensional vacuum.

A beautiful thing happens - by separating the 5-D Einstein equation into its components, we can come up with three very interesting, smaller equations. One describes something called a scalar field (don't ask!). Another is simply Einstein's equations in 4 dimensions, but right side of the equation is no longer 0 - rather, it describes a field of electromagnetic radiation! The third equation is perhaps the most shocking - nothing more or less than Maxwell's equations (condensed into one equation) describing the electromagnetic force.

So from higher-dimensional gravity, electricity and magnetism "appear" in 4 dimensions, and from a higher-dimensional vacuum, we get "stuff" - radiation! Light! Fantastic little result, and in many ways the basis of the higher-dimensional theories (such as string theory) that we have today. Higher dimensions seems to be useful for getting other forces out of gravity.

There are ways to extend this mechanism to include other forces, like the strong and weak force, and this has been tried with varying levels of success. There hasn't been a solution for the other forces quite as elegant and beautiful as the Kaluza-Klein solution, however, and correspondingly it's been difficult to make other particles besides photons appear from a higher-dimensional vacuum. Regardless, it is clear that there's more to gravity than meets the eye, and if there's but one higher dimension, hidden from our view, magnetism and electricity are, indeed, the same as gravity.

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#### yevaud

##### Guest
Oh yes, we are amply familiar with Kaluza/Klein here. After all, it's the bais for Yang-Mills that followed, and thus a major underpinning for the Standard Model of today, not to mention M-Theory.

An interesting aside is that Kaluza/Klein is itself based on the Euler Beta Function. The implication is that had he followed through on it, Euler could well have discovered the roots of KK, YM, and the Standard Model...in the middle 1800s!

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#### MeteorWayne

##### Guest
ramparts":213qnvh0 said:
I'm surprised that none of the people more familiar with GR have brought up Kaluza-Klein theory so far. .

Thanx for a very clear and concise explanation. You do pretty good at 3 AM!!

Wayne

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#### ramparts

##### Guest
yevaud":37gdz64i said:
Oh yes, we are amply familiar with Kaluza/Klein here. After all, it's the bais for Yang-Mills that followed, and thus a major underpinning for the Standard Model of today, not to mention M-Theory.

An interesting aside is that Kaluza/Klein is itself based on the Euler Beta Function. The implication is that had he followed through on it, Euler could well have discovered the roots of KK, YM, and the Standard Model...in the middle 1800s!

No way - now that's a big claim I'm curious, how is Kaluza-Klein based on the beta function? The papers I've read seem to approach it differently (or maybe just skipped the relevant part of the derivations).

Y

#### yevaud

##### Guest
Well, in 1968, Gabriele Veneziano stumbled onto the fact, when he found that the Beta function perfectly matched modern data on the Strong Nuclear Force. This conforms to Kaluza-Klein. In point of fact, this may be said to be the very beginning of String Theory

V

#### vividasday

##### Guest
Gravity & Magnetism the Same?

Gravity vs. Magnetism

I am so inspired by SPACE!!! We - can only IMAGINE!!!
IMO...

E

#### emperor_of_localgroup

##### Guest
ramparts":al6ooilp said:
I'm surprised that none of the people more familiar with GR have brought up Kaluza-Klein theory so far. It's not an answer to the OP's questions (which have to do with much simpler physics), but it's an absolutely beautiful piece of work, highly interesting, and is at least what I immediately think of when the question "are gravity and [electro]magnetism the same?" is asked. So, despite it being tangential, and 3 in the morning here, I think it's interesting enough to warrant a post And possibly a thread hijack.

A beautiful thing happens - by separating the 5-D Einstein equation into its components, we can come up with three very interesting, smaller equations. One describes something called a scalar field (don't ask!). Another is simply Einstein's equations in 4 dimensions, but right side of the equation is no longer 0 - rather, it describes a field of electromagnetic radiation! The third equation is perhaps the most shocking - nothing more or less than Maxwell's equations (condensed into one equation) describing the electromagnetic force.

There are ways to extend this mechanism to include other forces, like the strong and weak force, and this has been tried with varying levels of success. There hasn't been a solution for the other forces quite as elegant and beautiful as the Kaluza-Klein solution, Regardless, it is clear that there's more to gravity than meets the eye, and if there's but one higher dimension, hidden from our view, magnetism and electricity are, indeed, the same as gravity.

Interestingly my latest line of thoughts also point to such a direction. There may be only ONE fundamental force, and that force is gravity. All other forces are special cases of gravity. I can't explain it because there are lots of wrinkles in my chain of thoughts and need to be smoothed out. I'm surprised so far no scientist gave gravity a chance as the only fundamental force, it seems very obvious to me.

O

#### origin

##### Guest
I can't explain it because there are lots of wrinkles in my chain of thoughts ......it seems very obvious to me.

You can't explain it but it is obvious - this is really a pretty funny thing to say.

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