I just invented something that I think I'll call "Radio." Tell me where I'm wrong.

Factual Questions
1

I was taught little physics in high school, and absorbed even less, possibly having an undiagnosed ADD. Forty years later I’m trying to catch up by listening to popular science audiobooks while I drive. Of course, driving and having several other thought streams competing for attention means that I still don’t absorb much, but it’s more advanced than the stuff from high school, which stopped around Newton and Galileo. So please bear with me–this is all new to me.

Anyway, a visible electromagnetic field using a bar magnet and iron filings has always intrigued me, because without luminiferous æther (I know that I need to be quiet about that stuff, even as an explanation for Dark Matter) as the medium through which the field is propagated it wasn’t working in my head. Then it hit me: The magnetic field is bending space. And I’m guessing that if you use an electromagnet hooked up to a rheostat the field will vary as you vary the voltage. And the atoms in the antenna move as the varying field moves the space they are in, so they emit electrons in coordination with the bending and unbending of space.

I still haven’t invented the “tuner” and the “amplifier,” but I’m on a roll and should have them worked out in a few days. I invented the “loudspeaker” decades ago, so that’s set, just waiting for the rest.

So, how much of that is right and how much is the result of too little knowledge plus too much time on my hands waiting while my wife shopped?

2

Since quantum mechanics and relativity seem to be mortal enemies for the time being, it’s probably safe to say that no one truly understands how any of this works on the most fundamental level.

That said, I’ve seen posts here from people who are quite knowledgeable about the physics to the extent that it is understood and we (humans) do seem to have a pretty good handle on electromagnetic phenomena, so I don’t expect to do much better but you’ve given me courage. :slight_smile:

First, in relativity, it’s not space that is warped but spacetime and there is one school of thought that regards the time element as superfluous. However it does require curved space (yeah, don’t ask, no clue here either).

Second, there is an electric field and a magnetic field and they are always present together and orthogonal (I think I used that correctly). In this instance that just means that one propagates at a right angle to the other.

You can trade a loss of magnetic field strength for an increase in the electric field, which I think is how wireless chargers such as for a handheld rechargeable toothbrush work. Or can go the other way which I think is how things like electro-magnets work.

Honestly none of this ever made any sense to me either even with the ether. Magnetic fields do sort of. Dump some iron filings, see the fields lines. Check. The idea of an electric field though never really sunk in.

Anyway, what I think happens with radio is that you’re transmitting both an electric and magnetic field but the receiver is only designed to pick up one of them which is (eenie, meenie . . .) the ummm electric field (???). I don’t remember if it propagates better, has less interference or what.

That field is in some sense composed of massless photons which are force carrying particles in what is know as the Standard Model. But on the quantum level, every phenomenon is described by it’s wave function. You would think that implies that there are no particles but only waves. Actually it means that everything is both and neither. It depends on why you’re asking.

For the purposes of analyzing a radio signal, it’s best to consider photons as existing as an electromagnetic wave. It does happen to exist on the backdrop of the zero point quantum field which is the sea of constant oscillations of the quantum vacuum, but I’m not aware of there being any connection between that and wave propagation.

I’ll now wait for this post to be thoroughly decorated in red ink from all of the corrections it will require.

3

You and me, both. Finally exercising these brain cells is fun!

4

I was under the impression that quantum mechanics and relativity have, if not kissed and made up, figured out that one needs the other if it’s going to work.

My bad. I meant spacetime, but use space and spacetime interchangeably because I don’t know any better. But I thought…wait, you just mean that time requires curved space, but everything else just needs space that can be curved, right?

That’s new to me.

But how can a wave propagate if there is nothing to propagate in?

5

The proposition is that every varying electric field or magnetic field, is in a radio transmitter

Correct.

The proposition is that every varying electric field or magnetic field, is in a radio transmitter ONLY because the field bends space/timespace/special relativity.

Incorrect.

6

It works best if the field is generated by the conductor of one of the fields, and then the other field is generated and not immediately looped… so it forms its own loop and goes off an an EM wave…

In practice the antenna is an electric conductor and magnetic non-conductor,
as its hard to find a magnetic conductor that is not an electric conductor.

7

Okay, so what carries the wave? Bear in mind that all rumors that I’m an idiot are true and I’m perfectly happy to go back to ether because none of this is something I need to know to function in society, and am only getting into this because I need something to think about. And while I appreciate short paragraphs because I can’t follow walls of text, that answer could bear some expansion.

8

It is the electromagnetic field that is being bent, not space itself. At every point in space there is an electromagnetic field. Its value may be 0 at some points, but not when you introduce a magnet or a charged particle. I don’t think this requires quantum theory.

9

Really? But what really is a field?

This is what happens when you pick up things in dribs and drabs over the years, and spend too long reassembling a sentence you just heard so that you can grasp its meaning to hear the next two. One reason I play those books is for my wife, who is all scientificalistic. She knows all that junk already, but it helps her have sciencey and mathological dreams. Plus, there’s no commercials or politics or songs I’ve heard a million times, so I keep my blood pressure down.

I’ve also learned that Immanuel Kant was not just a philosopher and a real pissant who was very rarely stable, but was also a fairly brilliant astrophysicist. And that Lou Boudreau was not just an announcer for the Cubs, but a Hall of Famer at short and a pretty good manager.

No, that last one is from the print book I’m reading (slowly) at lunch. They won’t let me have an MP3 player at my desk because they are, at heart, thumb drives. Yes, my company is more secure than the NSA.

10

You don’t need a carrier. In fact, there’s every reason to believe that on the quantum level, space, in any sense we would comprehend, doesn’t even exist. The same goes for time. That sounds like gibberish but there is a great article in June 15th New Scientist on this.

11

Y’know, I realized I’d gotten past the “that sounds like gibberish” point when I heard Timothy Ferris (the sciencey one) say that, in some hypotheses, strings are shards of fractured spacetime, and my response was, “Okay. I can work with that for now.”

ETA: While I’m new at being a scientist, and am part of their apparent target demographic, I do not subscribe to the New Scientist and cannot read that article. :frowning:

12

Yes. I did know that in advance. I should have said something but my thought was that it might still be on newsstands since it’s the current issue.

edit: oh damn. It’s not current. June 22nd. is. OK, sorry again. :frowning: :o

13

On a mathematical level, a field is any quantity that has a point at every value in space and time. The electric field, for example, defines a vector at every point in space and time, pointing in the direction that a test charge would experience a force and proportional to that force’s magnitude.

But that’s the boring answer. Here’s the more interesting one: One of the main ideas to come out of the last 100 years of physics is that everything is a field. More precisely, there’s a field corresponding to every form of matter that we know about: the electromagnetic field, the gravitational field (sometimes called “the metric field”), the electron field, the quark fields (several types of those, depending on how you count them), the Higgs field, and so on. The Universe is, on a fundamental level, made of fields. Excitations of these fields are what we perceive as particles. How these fields interact with each other is described by the Standard Model (except for the gravitational field, which hasn’t quite be reconciled with the Standard Model as yet.) In a very real sense, fields make up the Universe; “particles” are mere constructs that can help us simplify the interactions of the fields in some situations.

14

Quantum mechanics works just fine with the Special Theory of Relativity, and in fact, all of the most successful theories of physics have come out of a combination of quantum mechanics and special relativity. It’s only when you try to combine quantum mechanics with general relativity that you get problems.

15

Well, there is the non-locality issue with respect to entanglement and I know I’m forgetting a few things, but yeah, that was what I was referring to, the fact that they seem to be irreconcilably incompatible.

16

[In physics] a field is something that is defined at every point in space (or spacetime for fields in relativity). The language used in physics is mathematics, so each the field at each point in space/spacetime is described by some mathematical object. Usually this mathematical object is a scalar (i.e. a number, usually a real number; e.g. 1,2,3, pi, etc), a vector (a quantity has a magnitude which is describe by a number, but also a direction e.g. velocity) or a tensor (a generalization of vectors and scalars which can describe fairly complicated things like how to multiply two vectors together at each point). Sometimes each point is described by even more esoteric, but similar, mathematical objects such as spinors.

We usually require that the field is smooth, which means that it can’t jump around from place to place with no rhyme or reason and it’s value at any given point must be somewhat related to it’s value at nearby points.

We also have to be a little bit wary of seeing the actual physical field as being the same as it’s mathematical description. Sometimes two mathematically distinct fields can be used to describe exactly the same physical field, this is known as gauge symmetry.

The electromagnetic field was originally described in terms of two related fields: the electric field and the magnetic field. However the prime theoretical motivator of the special theory of relativity was electromagnetism and when viewed in terms of relativity it is clear that the electric field and magnetic field can be described in terms of one field. The usual way to describe this field would be in terms of a tensor field defined on spacetime.

As I mentioned earlier we usually require the value of a field at one point to be somewhat related to its value at nearby points and this requirement means that changing its value at one point, must change its value at some other points too. Exactly how this change manifests itself depends on the field itself, but in the electromagnetic field these changes, within a certain limit, propagate at the speed of light and manifest themselves as electromagnetic radiation. So essentially all radio waves, light waves, etc are, are time-varying electromagnetic fields.

17

Except as I’m sure you know, the ‘quantum’ in quantum mechanics stands for precisely that sort of thing. OK, originally it meant quanta of energy, but one only needs to think of the popular idea of a ‘quantum’ leap to realize that it also applies to things jumping about. Quantum tunneling is an even better and more interesting example.

18

There you go, bringing the 20th Century into it! This was Physics for Liberal Arts Students in 1970. We barely touched on Relativity and it was mostly handwaved away as something nobody actually understood.

19

I don’t think this article is very good at all. The only evidence it offers for its headline is that in quantum mechanics (or more specifically the Schrodinger equation) time and space are treated on a different footing, whereas in relativity they’re treated on equal footings. However this is such a basic mistake: the Schrodinger equation is non-relativistic simply because it wasn’t formulated to be relativistic, not because of some fundamental clash between quantum mechanics and special relativity. Placing time and space on equal footings in quantum theory brings in additional complications, however these complications have now been considered to be resolved for a very long time. The article then goes on a whistle-stop tour of how time and space are treated in various approaches to quantum gravity, none of which really justifies its central premise.

20

Yes, that’s what the two fields were unified long ago. :rolleyes: