• Qualia. What is this subjective experience that I know as consciousness? I've gone through Wiki, SEP and a fair number of books on philosophy and a few on neuroscience but I still don't understand what it is that I experience as the color "red" when in reality it's just a bunch of electric fields (photons). Why can't I get the same experience — i.e., color — when I look at UV or IR photons? These too are the very same electric fields as the red, blue, green I see all the time.
• Photographic composition. I'm a designer. I know them. I use them. But only empirically. I just do not understand them at a neuroscientific level. Why does rule-of-thirds feel pleasing? Is the golden ration bullshit? My gut says yes but I'm unable to come up with a watertight rebuttal. Why do anamorphic ultra-widescreen shoots feel so dramatic/cinematic? Yet to see an online exposition on the fundamental reasons underlying the experience. Any questions to artists are deflected with the standard "It's art, not science" reply.
• Wave-Particle duality. "It's a probability wave that determines when a particle will pop into existence out of nothingness." okay, where exactly does this particle come from? If enough energy accumulates in a region of empty space, a particle pops into existence? What is this "energy"? What is it made of? What even is an electron, really? I've followed quite a few rabbit holes and come out none the wiser for it.
• Convolution. It's disappointing how little I understand it given how wide its applications are. Convolution of two gaussians is a gaussian? Convolution in time domain is multiplication in frequency domain and vice-versa? How do these come out of the definition which is "convolution is sliding a flipped kernel over a signal"?
The idea is that it is in this waveform until you do something to observe it. Observation requires an exchange of energy, i.e., an interaction. This is why there is always uncertainty, because in order to observe something, that which observes has now intimately interacted with the waveform in order to cause its "collapse" into what we consider to be a particle. A particle very well may just be a highly localized energy that we perceive to be "solid"
You can't, for example, try to get a measurement of the location of a photon without putting a measuring device which absorbs the energy of the photon, modifying its wave function and thus the probability of where it will decide to reveal itself at that point in spacetime.
note: I consider energy, fundamentally, to simply be the consequence of fluctuating. The fluctuation of one thing can interact with the fluctuation of another and, minding conservation, transfer "fluctuation". The direction of that transfer of energy relying may be due to the fact that entropy always increases along the arrow of time, i.e., energy likes to spread itself out just as heat goes from high concentration to low concentration.