Not all individual strands of hair will be exactly and perfectly cylindrical.
That’s an image using an electron microscope, which has VASTLY superior resolution that the simple visible-light methods used.
Hair is extremely elastic, so there’s no reason to assume it isn’t being deformed by tension. Which we know for a fact it is, because it’s tied in a knot.
Why would the photographer lie about using hair, and use something else instead? What motivation exists to be honest about a grain of sand, but dishonest about the hair?
Not all individual strands of hair will be exactly and perfectly cylindrical. That’s an image using an electron microscope, which has VASTLY superior resolution that the simple visible-light methods used. Hair is extremely elastic, so there’s no reason to assume it isn’t being deformed by tension. Which we know for a fact it is, because it’s tied in a knot. Why would the photographer lie about using hair, and use something else instead? What motivation exists to be honest about a grain of sand, but dishonest about the hair?
I’m not doubting the photographer if this was really what he said. I’m more so doubting what the OP said.