8 ms·

I always shy away from analogies because more often than not they give the wrong "feel" for a concept. But this is one of those rare exceptions.

Filligree 2y ago
It's not an analogy. This is precisely how it works.
- khazhoux 2y ago
  Unless your car radio consists of a flashlight and a tree, this is an analogy.
  - viraptor 2y ago
    Well... It kind of does. The source of the radio station is a kind of flashlight, just on a different frequency. The tree is still a tree (and all the other objects)
    - cloudwalk9 2y ago
      More accurately a giant lightbulb, but emitting at 102.7 MHz (my favorite local radio station) rather than ~450 THz (my favorite color). Put visible light over a really long waveguide and modulate the colors, you invented fiber optic telecommunication.
  - llm_trw 2y ago
    The flashlight is the radio tower, the tree is the tree, and the radio in the car is your eyes. There is no analogy here, it is literally the same EM waves shifted up to where our eyes can see them. It's like saying that the violins is merely an analogy for how a double base works.
    - JumpCrisscross 2y ago
      > it is literally the same EM waves shifted up to where our eyes can see them Rubber ducks aren't battleships because they both float. Visible light and radio attenutate in meaningfully-different ways. It's an analogy.
      - dexwiz 2y ago
        Rubber ducks and battleships both displace water in the same way.
        aksss 2y ago
        Ducks and witches, on the other hand. . .
        JumpCrisscross 2y ago
        > Rubber ducks and battleships both displace water in the same way 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.
        aeonik 2y ago
        But if you say that a battleship floats on the water in a similar way to a rubber duck floating in the water... it's actually not similar... they are the same. It's the same water and the same physics. The "only" appreciable difference is scale. 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.
        swores 2y ago
        > But if you say that a battleship floats on the water in a similar way to a rubber duck floating in the water... it's actually not similar... they are the same. It's the same water and the same physics. The "only" appreciable difference is scale. 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.
  - senorrib 2y ago
    Both concepts are based on frequency and amplitude of waves (radio vs light).
    - khazhoux 2y ago
      That's what makes the analogy so clear.
  - kelnos 2y ago
    Essentially that is actually the case. Human-visible light and AM/FM radio waves are just different wavelengths along the EM spectrum. A flashlight beams out waves that we can see; a radio transmitter beams out waves we can't. The brightness of the beam of light is related to its amplitude, just like the signal content in AM radio is related to its amplitude. And the color of the beam of light is related to its frequency, just like the signal content in FM radio is related to its frequency.
    - khazhoux 2y ago
      The explanation asks us to imagine shining a flashlight through a tree, first changing the flashlight brightness and then changing its color. The flashlight is an analogy for a radio transmitter. We all get that they work on same principle but just on different wavelengths. But regardless I can't shine the flashlight in my kitchen drawer at my radio and pick up a signal.
      - mordae 2y ago
        Remove cover, locate LNA, modulate light correctly and voila... :-)
Sesse__ 2y ago
It _is_ the wrong feel for a concept. The analogy breaks down because the color changes are way too wide in frequency (and thus too robust to noise) compared to what happens in a radio broadcast. If you changed the color from RGB(127, 0, 0) to RGB(126.999999, 0.000001, 0), the movement of that tree would actually start to make your strategy difficult. Going from red to orange is about 50 THz. Typical FM radio modulation width is 100 kHz.
- Workaccount2 2y ago
  The analogy isn't wrong, it's just that it is incomplete as given. You are bringing the sensitivity of the receiver into the equation. But it doesn't really break down the analogy, because the frequency shift in color is calibrated for the human eye's sensitivity. Calibrate it for a FM receiver and that tiny color shift becomes easily discernible. The tree leaves have no impact on frequency, just amplitude. The reason the analogy is good is because it isn't even really an analogy, it is in fact a description of electromagnetic waves and a noise source.
  - Sesse__ 2y ago
    > The tree leaves have no impact on frequency, just amplitude. That's an oxymoron, really. Frequency and amplitude are closely interrelated concepts (e.g. see Heisenberg's uncertainty principle in the context of signal processing). Frequency-varying and amplitude-varying even more so!

Filligree 2y ago

It's not an analogy. This is precisely how it works.

khazhoux 2y ago
Unless your car radio consists of a flashlight and a tree, this is an analogy.
- viraptor 2y ago
  Well... It kind of does. The source of the radio station is a kind of flashlight, just on a different frequency. The tree is still a tree (and all the other objects)
  - cloudwalk9 2y ago
    More accurately a giant lightbulb, but emitting at 102.7 MHz (my favorite local radio station) rather than ~450 THz (my favorite color). Put visible light over a really long waveguide and modulate the colors, you invented fiber optic telecommunication.
- llm_trw 2y ago
  The flashlight is the radio tower, the tree is the tree, and the radio in the car is your eyes. There is no analogy here, it is literally the same EM waves shifted up to where our eyes can see them. It's like saying that the violins is merely an analogy for how a double base works.
  - JumpCrisscross 2y ago
    > it is literally the same EM waves shifted up to where our eyes can see them Rubber ducks aren't battleships because they both float. Visible light and radio attenutate in meaningfully-different ways. It's an analogy.
    - dexwiz 2y ago
      Rubber ducks and battleships both displace water in the same way.
      - aksss 2y ago
        Ducks and witches, on the other hand. . .
      - JumpCrisscross 2y ago
        > Rubber ducks and battleships both displace water in the same way 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.
        aeonik 2y ago
        But if you say that a battleship floats on the water in a similar way to a rubber duck floating in the water... it's actually not similar... they are the same. It's the same water and the same physics. The "only" appreciable difference is scale. 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.
        swores 2y ago
        > But if you say that a battleship floats on the water in a similar way to a rubber duck floating in the water... it's actually not similar... they are the same. It's the same water and the same physics. The "only" appreciable difference is scale. 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.
- senorrib 2y ago
  Both concepts are based on frequency and amplitude of waves (radio vs light).
  - khazhoux 2y ago
    That's what makes the analogy so clear.
- kelnos 2y ago
  Essentially that is actually the case. Human-visible light and AM/FM radio waves are just different wavelengths along the EM spectrum. A flashlight beams out waves that we can see; a radio transmitter beams out waves we can't. The brightness of the beam of light is related to its amplitude, just like the signal content in AM radio is related to its amplitude. And the color of the beam of light is related to its frequency, just like the signal content in FM radio is related to its frequency.
  - khazhoux 2y ago
    The explanation asks us to imagine shining a flashlight through a tree, first changing the flashlight brightness and then changing its color. The flashlight is an analogy for a radio transmitter. We all get that they work on same principle but just on different wavelengths. But regardless I can't shine the flashlight in my kitchen drawer at my radio and pick up a signal.
    - mordae 2y ago
      Remove cover, locate LNA, modulate light correctly and voila... :-)

Sesse__ 2y ago

It _is_ the wrong feel for a concept. The analogy breaks down because the color changes are way too wide in frequency (and thus too robust to noise) compared to what happens in a radio broadcast. If you changed the color from RGB(127, 0, 0) to RGB(126.999999, 0.000001, 0), the movement of that tree would actually start to make your strategy difficult. Going from red to orange is about 50 THz. Typical FM radio modulation width is 100 kHz.

Workaccount2 2y ago
The analogy isn't wrong, it's just that it is incomplete as given. You are bringing the sensitivity of the receiver into the equation. But it doesn't really break down the analogy, because the frequency shift in color is calibrated for the human eye's sensitivity. Calibrate it for a FM receiver and that tiny color shift becomes easily discernible. The tree leaves have no impact on frequency, just amplitude. The reason the analogy is good is because it isn't even really an analogy, it is in fact a description of electromagnetic waves and a noise source.
- Sesse__ 2y ago
  > The tree leaves have no impact on frequency, just amplitude. That's an oxymoron, really. Frequency and amplitude are closely interrelated concepts (e.g. see Heisenberg's uncertainty principle in the context of signal processing). Frequency-varying and amplitude-varying even more so!