This just seems like the magical, "aether" like there is no mass to use to transfer energy, so it must be propagating irrelevant to physical mass.

Yeah, my first thought about fields was "Isn't this just the aether in fancier clothes?" But the distinction is profound: to the 19th century physicist, the aether was a fluid that filled all of space, i.e., it was something that existed in space. The problem was that no one could explain how this incompressible, massless, zero-viscosity fluid actually worked. And when the Michelson-Morley experiment couldn't detect it (no big surprise there), physicists abandoned the notion of an aether.

To the 21st century physicist, however, fields don't exist in space -- rather, space is made of fields. This isn't just a semantic distinction; QFT describes precisely and in a falsifiable way how interactions between these fields give rise to all the components of matter. In other words, where the aether was an explanation of EM propagation through space, fields are a full theory of matter.

OK. I can fire a laser into space, and the light travels just fine. I think radio frequency energy would do the same. It can even be focused with a parabolic antenna. Just it isn't wiggling any mass so it must be just radiating like light??? It is, in and of itself, traveling on its own energy?

The energy comes from the source, e.g., the radio transmitter. You use energy to wiggle the field, and that propagates as EM radiation. Both the laser and the radio transmitter are working with the same kind of stuff, electromagnetic energy. The only difference between visible light and radio waves is frequency.

 

To the 21st century physicist, however, fields don't exist in space -- rather, space is made of fields.

That is very close to my own interpretation... that fields are the very fabric of space-time.

The only difference between visible light and radio waves is frequency.

Exactly the way I think too.

 

It's all because we live in an eleven dimensional super reality.

I've just watched that video... and I'm feeling dizzy... this is the most interesting thread I've participated in in a long time...

 

I've just watched that video... and I'm feeling dizzy... this is the most interesting thread I've participated in in a long time...

That video is instructive on how we understand the nature of electromagnetic energy using a higher dimensional construct that unifies the electric and magnetic fields we see in our 3D universe. We have all heard about a time varying electric field gives rise to a time varying magnetic field and vise versa. That sounds great until we look for a cause and effect of why that's happening instantaneously over the space of a moving wave in a universe where cause and effect is limited over space by light speed. If we imagine the electromagnetic energy as a 4D entity then we can have what looks like in our 3D universe to be instantaneous changes by rotations or translations in the 4D objects 3D shadow like the 2D ant moving on a 3D surface.

Electric and magnetic fields are what the electromagnetic field 'looks like' from a particular (inertial) frame of reference.

Dizzy?

 

That video is instructive on how we understand the nature of electromagnetic energy using a higher dimensional construct that unifies the electric and magnetic fields we see in our 3D universe. We have all heard about a time varying electric field gives rise to a time varying magnetic field and vise versa. That sounds great until we look for a cause and effect of why that's happening instantaneously over the space of a moving wave in a universe where cause and effect is limited over space by light speed. If we imagine the electromagnetic energy as a 4D entity then we can have what looks like in our 3D universe to be instantaneous changes by rotations or translations in the 4D objects 3D shadow like the 2D ant moving on a 3D surface.

Electric and magnetic fields are what the electromagnetic field 'looks like' from a particular (inertial) frame of reference.

Dizzy?

The hypercube is an object that long ago I learned to accept as unvisualizable, except by projecting its three-dimensional shadow in our own reality. It has helped me learn that some mathematical concepts can be intuited from previously grasped principles. But for most of us, it's almost impossible to make the huge intellectual leap of abandoning graphic interpretations, for our minds to finally plunge into abstract ones.

 

Mr. Pragmatic accepts the demonstrated facts that radio waves travel and gravity sucks. Getting a grip on the how and why of it is a whole 'nuther matter.

I recently speculated: that we aren't walking on this planet because of gravity, but we are walking on a curve in space-time and there is no such thing as a mysterious force called "gravity". Gravity is merely a manifestation of the curvature of space-time and does not exist as a primary force. Meanwhile, electrical fields and their associated magnetic fields propagate entirely irrelevant to the presence or absence of physical matter.

I think I'll go fix a truck. It makes more sense to me.

Grab the surf board, it is time to hit the waves! http://www.pbs.org/wgbh/nova/next/physics/big-ideas-of-2016-gravitational-waves-rocked-the-world/

 

... An interesting point, explained by Feynman in one of his lecture books ... Electric field strength, say the field generated by a dipole antenna, attenuates ... or decreases ... in proportion to 1/R, where R is the distance from the antenna. However, the associated magnetic field, produced simultaneously, attenuates in proportion to 1/R^2. Consequently, the E field can propagate vast distances and still have sufficient signal strength to be received, amplified, and have some utility. Magnetic fields, however, are strictly local, in the near field sense, around the antenna, and serve no useful purpose.

 

... An interesting point, explained by Feynman in one of his lecture books ... Electric field strength, say the field generated by a dipole antenna, attenuates ... or decreases ... in proportion to 1/R, where R is the distance from the antenna. However, the associated magnetic field, produced simultaneously, attenuates in proportion to 1/R^2. Consequently, the E field can propagate vast distances and still have sufficient signal strength to be received, amplified, and have some utility. Magnetic fields, however, are strictly local, in the near field sense, around the antenna, and serve no useful purpose.

First, that's just not true for far field EM waves as the associated magnetic field is in exact portion to the electric field and is easily received by every AM radio ferrite magnetic field antenna made.

https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/RadCom/part7/page5.html

 

First, that's just not true for far field EM waves as the associated magnetic field is in exact portion to the electric field and is easily received by every AM radio ferrite magnetic field antenna made.

https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/RadCom/part7/page5.html

The electromagnetic radiation of a dipole antenna is such that the E field component has a direction that is perpendicular to the wire antenna axis. The magnetic field component, generated by the same moving charges in the wire, is directed cicumferentially about the wire, and is local in nature, being weak at any significant distance. It must be pointed out that the perpendicularly radiating E field is what serves to allow useful communication at a distance, in this particular instance.
Radar antennas, microwave dishes, optical transmitters ... have different radiation patterns and characteristics.

The text linked here has a more general explanation:
http://www.feynmanlectures.caltech.edu/I_toc.html
Volume I, Chapter 28 on radiation might be of interest.

 

The electromagnetic radiation of a dipole antenna is such that the E field component has a direction that is perpendicular to the wire antenna axis. The magnetic field component, generated by the same moving charges in the wire, is directed cicumferentially about the wire, and is local in nature, being weak at any significant distance. It must be pointed out that the perpendicularly radiating E field is what serves to allow useful communication at a distance, in this particular instance.
Radar antennas, microwave dishes, optical transmitters ... have different radiation patterns and characteristics.

The text linked here has a more general explanation:
http://www.feynmanlectures.caltech.edu/I_toc.html
Volume I, Chapter 28 on radiation might be of interest.

You are only reading half the story, there are more antenna types than dipoles so you can't generalize EM propagation in free space because of one type of near field antenna operation. Most AM band stations transmit using a 1/4 wave tuned vertical antenna that uses the ground plane to image a dipole so the E field component has a direction that is perpendicular to the wire antenna axis. On the receiver end most of the same AM stations are received using magnetic antennas that are not very sensitive to the E field component. The key to see how this is possible is to understand that EM wave energy is not separate fields moving into space, it is a single entity that has both components.

All of those antenna effects pertain to the near field and the use of a dipole antenna antenna that's sensitive to the E field component. Loop and magnetic antennas are sensitive to the H field component and work perfectly well to transmit and receive electromagnetic energy with proper matching.

 

If EM waves are transverse, why can't I place my antenna on any half wave distance node and hear silence?

Linear means one direction. Fixed density patterns (angular patterns) is the only option.

 

Doesn't it take two signal sources, emitting similar waves, and separated by some distance, to form nodes and troughs?

 

Maxwell said that the electric and the magnetic scissor as they propagate. Other people think the E and M rotate during propagation in space.

If it did, the scissor or rotation would be timed with distance. If that's true, at the distance proportional to zero crossings, the signal is zero. We could not receive that signal at that distance with that frequency.

Does that make any sense?

 

If EM waves are transverse, why can't I place my antenna on any half wave distance node and hear silence?

Is that a trick question? The wave itself is in motion. For what you're saying to happen you'd have to move in sync (same direction and speed) with the wave. That means you'd have to move at the speed of light, which is impossible.
And it wouldn't matter where along the wave you'd be, be it node or crest.

 

Maxwell said that the electric and the magnetic scissor as they propagate. Other people think the E and M rotate during propagation in space.

If it did, the scissor or rotation would be timed with distance. If that's true, at the distance proportional to zero crossings, the signal is zero. We could not receive that signal at that distance with that frequency.

Does that make any sense?

No

 

If EM waves are transverse, why can't I place my antenna on any half wave distance node and hear silence?

You can under the right conditions (standing waves).
You can easily see the effect in any microwave by looking at the standing wave heating pattern.

 

Well I certainly am bamboozled now. I guess that proves it.

 

You can under the right conditions (standing waves).
You can easily see the effect in any microwave by looking at the standing wave heating pattern.

Aren't standing waves created by interference patterns? You have to get more than one wave (or an additional reflection of the original) into the mix to accomplish that effect, right?

 

If we don't understand one emission......how can we understand their interaction?

 

Aren't standing waves created by interference patterns? You have to get more than one wave (or an additional reflection of the original) into the mix to accomplish that effect, right?

Yes, it's an interference pattern. The standing wave is not actually a wave but rather a pattern that results from the interference of two or more waves.