electromagnetic fields and empty space

nouveau_riche

is it possible for electromagnetic field to exist without matter?

CompuChip

Yes, it is.
That's one of the particulars of 20th century physics.
People have thought for a long time that electromagnetic fields should propagate through some medium, in the same way that water waves or sound do. To explain EM waves propagating through vacuum they invented the concept of something called ether, permeating throughout space.
Ironically the experiment of Michaelson and Morley, which intended to prove the existence of that substance, was one of the major factors in discarding it.

Drakkith

Yep! Just look at a photon!

timthereaper

Doesn't the EM field require the existence of charged particles to form?

ecneicS

light isn't a charged particle but it is an oscillating ripple in the EM field. But I couldn't tell you why.

mathfeel

I think what OP wants to know is that electromagnetic wave can propagate without a medium, but can you create them without charged matter somewhere. Yes, You need some oscillating charge somewhere to create them, except maybe for fluctuation of the vacuum.

On the other hand, one predicted death of the universe is that everything, including proton, decays to photons so far away from each other that they never interact. So I suppose that'd be the case of photon without matter.

Drakkith

Remember that according to current science, the universe itself was once all photons. So where did those photons come from if they needed charged particles to create them?

DaleSpam

In principle it would be possible to have a universe with no charges, but with radiation. The early universe was radiation-dominated.

Edit: looks like Drakkith beat me to it!

Dotini

The early universe was dominated by ionizing radiation, wasn't it? So charge must have preceded matter.

Respectfully,
Steve

DaleSpam

The phrase "ionizing radiation" just refers to radiation of sufficiently high energy that it could ionize an atom. It by no means implies anything about its origin.

nouveau_riche

i asked for electromagnetic fields to exist without matter,that itself excludes photon

Drakkith

How so? Photons ARE electromagnetic fields. Or rather oscillations in them or whatever. If photons existed before matter then that is an example of EM fields existing without matter.

nouveau_riche

because photon itself is matter

Drakkith

No, photons are not matter. They are electromagnetic radiation.

mikeph

Hold on- at sufficiently high temperatures there is the matter-antimatter-radiation equilibrium, and when the temperature drops, matter and antimatter combine to form radiation and whatever is left. It's at this point that you look and see that there are many more photons than protons/electrons, and conclude "the early universe was radiation dominant"...

Radiation dominant doesn't mean there wasn't matter, simply that the matter/antimatter difference was so slight that when they combined, most of the matter was converted to radiation, leaving a small amount of matter, and a relatively large amount of radiation (dominant == considerably higher energy density).

I don't believe radiation dominant can be used for an argument that the electromagnetic field can exist without there ever previously being any charge present. That radiation came from charge/anticharge interactions in the first place.

nouveau_riche

so what makes matter as matter?how can photon exist without existence of matter?

Dotini

Maybe photons would exist, but would you know it unless it had a material surface to light up?

I see electrons, protons and other subatomic particles coming together from the regime of ionizing radiation to form atoms and molecules.

Respectfully submitted,
Steve