If you shine a flashlight through a tree blowing in the wind and vary the brightness to convey information, the signal can get distorted pretty easily.
However, if you have a constant brightness source and vary the color, it’s a lot easier to figure out what the source is trying to convey.
It's like saying that the violins is merely an analogy for how a double base works.
Rubber ducks aren't battleships because they both float. Visible light and radio attenutate in meaningfully-different ways. It's an analogy.
Lol news to me and my physics degree, Do tell because as far as I'm aware Maxwell's equations don't have an asterisk on them that say "doesn't work below 1 GHz".
Yes. Just like light and radio waves are both EM. A rubber duck remains an analogy for the buoyancy of a battleship. Not "literally the same" thing.
Did you really just pull out Maxwell's equations?
EM interacts with matter in different ways. Glass hardly attenuates visible light, but wood does. 2.4 Ghz can pass through walls better than 5Ghz.
There's the concept of permittivity wherein Maxwell's equations are defined in free space with vacuum permittivity.
https://en.wikipedia.org/wiki/Vacuum_permittivity#Permittivi...
To accurately model EM waves, you need more than just Maxwell's equations. You require material equations to model interactions of EM with media.
If you want to get really advanced, whereas Maxwell's equations are classical physics, there's Quantum electrodynamics (QED) which can model interactions of EM and matter.
https://en.wikipedia.org/wiki/Optical_fiber#Mechanisms_of_at...
Same with communications over coax. Obviously visible light doesn't transmit well over copper, but a spectrum of radio waves do, some better than others.
If the ocean were as clear as your average long-distance fiber cable, you would see down to the bottom of the Mariana Trench (also in the range of visible light, AFAIK).
Clear in certain wavelengths. Depends on the composition of the glass.
https://en.wikipedia.org/wiki/Optical_fiber#/media/File:Si_Z...
Silica glass behaves differently from ZBLAN (fluorozirconate glass).
Which goes to show how complicated EM interactions with media can be. It's generally easier to just empirically measure attenuation through some medium and use the empirical measurements as a model.
For me, the people saying they are the literal same thing are the same type of people that gave me that "aha" moment that really helped solidify my understanding of RF.
It was pretty mind blowing when I Understood that AM is a change in brightness and FM was a change in color. We just can't see RF, but if we could, that's what it would be.
> You require material equations to model interactions of EM with media
> Quantum electrodynamics (QED) which can model interactions of EM and matter.
It's amazing how condescending some people on here are; how could you possibly have missed literally in the first sentence of my response
> ... my physics degree
It’s a terrific analogy. OP is arguing that it isn’t an analogy but an identity. For what should be obvious reasons, it isn’t. And in this case, the difference between analogy and our best model of reality is material.
You don’t see how one being able to attenuate around a hill while another needs line of sight isn’t material to the way we use light and radio waves?
You literally started your comment with "Lol news to me", then you used your degree as if it made you more knowledgeable than anyone else here. Take a look in the mirror?
> ... Do tell
I did?
The extra information isn't to condescend. It's for other people that want to know more about the science.
But battleship doesn't equal floating in water, floating in water is a property it has.
If you're saying "the way a battleship floats in water is like how a rubber duck floats in water" then it's not an analogy, it's as you say just describing two versions of the same thing.
But it is an analogy to directly compare the two objects, because "floating on water" is a property of the objects it's not the object you are comparing.
Wikipedia begins its page on analogies with this, sourced from The Oxford Companion to the English Language: "Analogy is a comparison or correspondence between two things (or two groups of things) because of a third element that they are considered to share."
Or Marriam-Webster: "a comparison of two otherwise unlike things based on resemblance of a particular aspect"
Apart from rubber ducks and battleships both having the "third element", or aspect, of "primarily used for floating on water", they are definitely two completely different things. Nobody could look at a rubber duck next to a warship and say "they seem to be the same thing".
The more closely related two things are the more useful and less stretched the analogy available, which is why the analogy about radio waves was so enlightening to so many people in this thread. But it's bang on as the definition of what an analogy is.
IIRC, when Corning Co. first started working on optical fibers, the best available glass would be good for sending signals about ten meters. What was improved was not the total internal reflection; it was the purity of the glass.
