It seems like any color or sound can be accurately encoded (and recreated) with just a few numbers. Yet that doesn’t seem to be the case with smell or flavor. You can take a photo or sound recording and it’ll be a faithful recreation, but there’s no way to do that with smells or flavors. Is it a technology limitation or is there something fundamental to them that makes it harder to encode?
In: Physics
Vanilla is primarily dominated by one chemical, vanillin. It has a bunch of other minor volatile compounds, but you can ‘fake’ it with just the one. Raspberry is another, the primary ketone 4-(4-hydroxyphenyl) butan-2-one (RK) can be perceived as raspberry even without the minor supporting chemicals. However, you can’t realistically produce Vanillin and RK from the same chemical “speaker” – they’re totally different things.
The smell of strawberries, on the other hand, is made of up to 360 individual volatile chemicals, none of which can stand alone and need to be at specific concentrations in relation to each other. Even if you have the same chemicals, if you get the concentrations wrong, your brain will not perceive it as strawberry, e.g. it might come off as rotten/fermented.
Even the same chemical can smell differently at different concentrations – “Dimethyl sulfide is important for fruit flavours, but also at certain concentrations gives the smell of the sea.”
Sound is one thing, the perceived pressure of vibrations at various frequencies and amplitudes in the air against one receptor, our eardrums. Color is the wavelength and amplitude of photons hitting our eyes, which only have to condense information from two different types of receptors – rods and cones.
Smell is the interaction of tens or hundreds or thousands of chemicals, all of which are made up of different molecules which are made up of different atoms, all at various concentrations, interacting with hundreds of different types of smell receptors.
To put it another way, think of those pin impression toys that you can press your hand or face into. Each sound from a speaker could leave an impression in the same board, and you can tell them apart. You can do the same thing with a smell, but instead of just storing the depth of the pins, you’re also changing the color of the individual pins, and their size, and their shape, and their material, and it changes with time, etc. And we can and do store all that information in various ways, but there’s still no existing technology that can reproduce the million billion trillion possible combinations of stuff on the fly out of some universal base material like sound or light can.
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