Edit: the 2 comments below give a pretty good explanation as to why the following comment is not correct. Original comment, as always:
I don’t see why they’d have to have big eyes. We use massive radio telescopes for sensitivity, not for the spectrum range. AM radio is in the order of 100 meter wavelengths, but handheld devices can receive it. Wavelength isn’t really the defining factor as much as being able to handle the frequency of the data over the time required. Wavelength is not how tall the wave is, amplitude is.
Handheld devices can receive it, but to actually “see” with it you need a very large aperture(iris) and a “retina” with many of those antennas that respond to different wavelengths. The overall structure of an eye capable of seeing would be massive, not because the signal is faint or you can’t “fit” the amplitude in the aperture but because that’s what you need for acuity and to actually have meaningful angular resolution. Those long waves have more limited angles to fit in a given eye diameter. For something like AM, we’re talking a very big structure.
θ ≈ λ/D where θ is the angular resolution, λ is the wavelength, and D is the diameter of the aperture
As you can see, increasing the wavelength by orders of magnitude means you need to increase the aperture by orders of magnitude to get the same angular resolution.
Massive singular radio telescopes are used to pick up individual signals from one direction, and can’t do imaging alone.
Sure you can pick up long wave radio with smaller antennas, but not without trade-offs. They often need long coils, and to make up the remaining difference you need to very precisely control electric resonance, and you lose efficiency (you pick up less energy from the radio waves). You definitely can’t do imaging with just one.
Just look at how big NFC and Qi coils are, they can’t practically be made smaller at those wavelengths, or else you lose too much energy!
Massive radio telescope arrays spanning the globe uses the massive distance to create a tiny amount of angular resolution, just enough that with months of processing you can image a black hole a few light years away with some thousands of pixels. Compare to how your phone can run deblur algorithms on a fraction of the power over far more pixels, because the angular resolution makes such a huge difference (blur radius is infinitely smaller)
Also, amplitude is signal strength. That’s only tall on a chart.
Alright, I think I can see I was picturing data in the wrong dimension. The data for an AM radio, in a very human-like interpretation, is running along the time axis rather than actual width across the available sources. It’d take multiple radios to “see” multiple frequencies.
Edit: the 2 comments below give a pretty good explanation as to why the following comment is not correct. Original comment, as always:
I don’t see why they’d have to have big eyes. We use massive radio telescopes for sensitivity, not for the spectrum range. AM radio is in the order of 100 meter wavelengths, but handheld devices can receive it. Wavelength isn’t really the defining factor as much as being able to handle the frequency of the data over the time required. Wavelength is not how tall the wave is, amplitude is.
Handheld devices can receive it, but to actually “see” with it you need a very large aperture(iris) and a “retina” with many of those antennas that respond to different wavelengths. The overall structure of an eye capable of seeing would be massive, not because the signal is faint or you can’t “fit” the amplitude in the aperture but because that’s what you need for acuity and to actually have meaningful angular resolution. Those long waves have more limited angles to fit in a given eye diameter. For something like AM, we’re talking a very big structure.
https://en.m.wikipedia.org/wiki/Angular_resolution
θ ≈ λ/D where θ is the angular resolution, λ is the wavelength, and D is the diameter of the aperture
As you can see, increasing the wavelength by orders of magnitude means you need to increase the aperture by orders of magnitude to get the same angular resolution.
I realize now I was thinking of data in the time axis rather than the width/resolution direction
Massive singular radio telescopes are used to pick up individual signals from one direction, and can’t do imaging alone.
Sure you can pick up long wave radio with smaller antennas, but not without trade-offs. They often need long coils, and to make up the remaining difference you need to very precisely control electric resonance, and you lose efficiency (you pick up less energy from the radio waves). You definitely can’t do imaging with just one.
Just look at how big NFC and Qi coils are, they can’t practically be made smaller at those wavelengths, or else you lose too much energy!
Massive radio telescope arrays spanning the globe uses the massive distance to create a tiny amount of angular resolution, just enough that with months of processing you can image a black hole a few light years away with some thousands of pixels. Compare to how your phone can run deblur algorithms on a fraction of the power over far more pixels, because the angular resolution makes such a huge difference (blur radius is infinitely smaller)
Also, amplitude is signal strength. That’s only tall on a chart.
Alright, I think I can see I was picturing data in the wrong dimension. The data for an AM radio, in a very human-like interpretation, is running along the time axis rather than actual width across the available sources. It’d take multiple radios to “see” multiple frequencies.