Why do magnetic fields attract only materials like iron and why do gravitational fields attract everything?

[Astrodob]

So gravitational fields attract everything because of the mass of the object creating it like the Earth,but then why does the heated core made out of a nickel-iron alloy increase this since gravitational fields are diffrent from magnetic fields?

[ronin]

The post does not quite seem to match the title, or at least I am thick enough not to see the relationship.

Megnetism is apparently a force A attracts/repels B, Gravity is looking more and more like an effect that we explain in terms of a force.

The other simple answer is they are different, why should they operate the same?

Mass distorts space/time, so far it appears magnetism does not, so they are, and operate, differently. A big heavy magnet has no more distortion on space/time then a big heavy non-magnet.

[Ptarmigan]

So gravitational fields attract everything because of the mass of the object creating it like the Earth,but then why does the heated core made out of a nickel-iron alloy increase this since gravitational fields are diffrent from magnetic fields?

As ronin says, there is a bit of a disconect there !

The core is massive, it is part of the mass of the earth. The earth's gravity is thus partly defined by the mass of the core.

But if you want to talk about magnetism and gravity in the same breath then we should start with Maxwell who had the good fortune to live in a cool universe.

At this time in this cool universe we can observe that the magnetic and electric fields can be combined into a unified electromagnetic field.

When the universe was a bit younger, hotter, more energetic, condensed, the e-m can be unified with the weak and strong nuclear interactions.

This can be observed at CERN and elsewhere.

If we suppose that at some even earlier epoch gravity can be combined with those intereractions and you can find the TOE that explains it you will surely be awarded a Nobel

[Astrodob]

So what is a field like a magnetic or gravitational one its invisible i know that,but u can see its effects.Since everything is made out of particles could even a magnetic/gravitational field be made out of some form of particles.Even electricity is a form of particle (electrons) so why cant an electric field be a particle.Or is it just energy which is invisible made out of nothing,but its there... and we dont understand it fully.

[acey]

So gravitational fields attract everything because of the mass of the object creating it like the Earth,but then why does the heated core made out of a nickel-iron alloy increase this since gravitational fields are diffrent from magnetic fields?

Can you say where you heard this? You're possibly referring to an effect of general relativity rather than Newtonian gravity. In general relativity the sources of gravity are energy density and pressure. Mass is equivalent to energy so it's a source. But if the energy density is increased (e.g. by heating) or the pressure is increased (e.g. in the cores of very dense stars) then the field is increased.

Your other question: "Why do magnetic fields attract only materials like iron and why do gravitational fields attract everything?"

Since energy density is a source of gravity, everything with energy feels gravity, and that's everything.

Magnetism is felt by things with electric charge, e.g. electrons. If the electrons orbiting an atomic nucleus have a certain arrangement then the magnetic effect can be very strong - this is what happens in the case of ferromagnetic materials. But every atom is in a sense a little magnet (it has a "dipole moment") which is how MRI (magnetic resonance imaging) works in hospitals.

[Astrodob]

Can you say where you heard this? You're possibly referring to an effect of general relativity rather than Newtonian gravity. In general relativity the sources of gravity are energy density and pressure. Mass is equivalent to energy so it's a source. But if the energy density is increased (e.g. by heating) or the pressure is increased (e.g. in the cores of very dense stars) then the field is increased.

Your other question: "Why do magnetic fields attract only materials like iron and why do gravitational fields attract everything?"

Since energy density is a source of gravity, everything with energy feels gravity, and that's everything.

Magnetism is felt by things with electric charge, e.g. electrons. If the electrons orbiting an atomic nucleus have a certain arrangement then the magnetic effect can be very strong - this is what happens in the case of ferromagnetic materials. But every atom is in a sense a little magnet (it has a "dipole moment") which is how MRI (magnetic resonance imaging) works in hospitals.

Mass has got something to do with it and density too you can have a lot of dense stuff and u can have less dense stuff (mass).

[Astrodob]

Mass is a property that determines the bodyes resistence to beeing accelerated by force... So it has something to do with Mass.The Earth is an enormus object and of course its big and dense so it will have a big mass,an asteroid is small and isnt dense therefore it will have smaller mass.So what will have a stronger gravitational pull? The Earth of course...

[Astrodob]

Can you say where you heard this? You're possibly referring to an effect of general relativity rather than Newtonian gravity. In general relativity the sources of gravity are energy density and pressure. Mass is equivalent to energy so it's a source. But if the energy density is increased (e.g. by heating) or the pressure is increased (e.g. in the cores of very dense stars) then the field is increased.

Your other question: "Why do magnetic fields attract only materials like iron and why do gravitational fields attract everything?"

Since energy density is a source of gravity, everything with energy feels gravity, and that's everything.

Magnetism is felt by things with electric charge, e.g. electrons. If the electrons orbiting an atomic nucleus have a certain arrangement then the magnetic effect can be very strong - this is what happens in the case of ferromagnetic materials. But every atom is in a sense a little magnet (it has a "dipole moment") which is how MRI (magnetic resonance imaging) works in hospitals.

What are the fields made out of,just pure energy or what?

[Ptarmigan]

just pure energy or what?

It might be a good idea to define what you mean by 'pure energy' and what the units are ?

Then we (both, or all) can decide what else the 'what' might be.

[acey]

There's no such thing as "pure energy". Einstein tells us us (E=mc^2) that mass and energy are equivalent. "Pure energy" would be equivalent to "pure mass". The word energy has an informal meaning outside physics, and when people speak of "pure energy" they're invoking that informal meaning. Other informal expressions of the same kind would be "pure power", "pure force", "spirit" etc.

[Ptarmigan]

But it is a valid question for Astrodob to ask :

"what is it made of"

After all, the talking heads on the box (no names no pack drill ! ) usually illustrate the fields with rubber sheets and ball bearings

or, in the case of the Higgs they employ treacle, and raisins spontaneously  in high temperature fairy cakes !!

Given those analogies it is hardly surprising that us mortals wonder what these 'fields' are composed of.

We can get awfull lost in english and semantics when contemplating interacting gauge, or 'mediating',  particles in Feynman diagrams

[acey]

If there were something more fundamental than the fields then you could say that's what they were "made" of, and would then ask what those more fundamental things are "made" of. Rubber sheets, treacle, or Faraday's "lines of force" are pictures. It's possible to say how the fields behave, and use the concept to make accurate predictions. Maybe that's as far as it goes. Maybe superstrings are more fundamental, and we ask what superstrings are made of. Perhaps "made of" is just not the right way to think of it.

Before quantum field theory, if you asked what an electron was made of, the answer would have been "electron stuff", or something like that. The electron was considered fundamental, not made of anything other than its whole self.

[Astrodob]

If there were something more fundamental than the fields then you could say that's what they were "made" of, and would then ask what those more fundamental things are "made" of. Rubber sheets, treacle, or Faraday's "lines of force" are pictures. It's possible to say how the fields behave, and use the concept to make accurate predictions. Maybe that's as far as it goes. Maybe superstrings are more fundamental, and we ask what superstrings are made of. Perhaps "made of" is just not the right way to think of it.

Before quantum field theory, if you asked what an electron was made of, the answer would have been "electron stuff", or something like that. The electron was considered fundamental, not made of anything other than its whole self.

I think its going to be something like a particle with a field or a particle and a wave(something like light,but u can see it and something to do with dark matter).

[Dan Leach]

Everything is attracted to gravity because gravity (unlike other forces) doesn't work across spacetime, it warps spacetime.

[ollypenrice]

If I could step into the future the thing I really would like to know is whether or not we will ever have a conceptual grasp of the quantum world which seems as reasonable to us as a bat propelling a ball by hitting it or a horse towing a barge by means of a rope. I don't think we will, personally, because qualitiative or conceptual explanations seem to be receding rather than approaching...

To quote the Goons out of context, I think modern physics really does 'mean the end of the horse drawn zeppelin...'

 lly

[Ouroboros]

I assume the question in the title asks in what way are magnetic and gravitational fields different and how does this difference arise. Gravitational force arises from the attraction between objects with mass. In simplistic terms magnetic force arises from the movement of electric charge. This occurs at the atomic level due to electron spin. Materials which are capable of being magnetised, like iron, have atoms with unpaired electrons which can line up collectively in a magnetic field. In this way the lump of iron becomes a magnet and can experience the force of magnetism. Other materials, including aluminium for example, do not have unpaired electrons so they can't be magnetised.

[ollypenrice]

I assume the question in the title asks in what way are magnetic and gravitational fields different and how does this difference arise. Gravitational force arises from the attraction between objects with mass. In simplistic terms magnetic force arises from the movement of electric charge. This occurs at the atomic level due to electron spin. Materials which are capable of being magnetised, like iron, have atoms with unpaired electrons which can line up collectively in a magnetic field. In this way the lump of iron becomes a magnet and can experience the force of magnetism. Other materials, including aluminium for example, do not have unpaired electrons so they can't be magnetised.

I'm not a physicist but from my readings and studies in astronomy I don't agree with this as a description of GR. My understanding is that there is no attraction between massive bodies. This is more like Newtonian gravity and was the very thing that troubled Newton himself. Rather, in GR massive bodies distort their local spacetime and, having done so, move differently within that spacetime and look as if they are attracting each other. A nice example I read described two pilots setting off from the equator a thousand miles apart at the same time and at the same speed. They both set an accurate course towards the same pole by plotting a trajectory at right angles to the equator and sticking to it.  They collide and bail out over the north pole. While waiting for rescue they discuss what force might have brought them into collision. But no force is needed. It's all geometry.

Olly

[Ouroboros]

You are of course correct. I was trying to provide a short and simple description of how the differences between gravitational and magnetic fields arise.