What is the fate of a photon after it hits the retina and is absorbed by an Opsin Molecule?
In: Physics
It ceases to exist. It was a wave, the wave hit something, and the wave died while that something took the impact. It’s like asking what happens to the sound that hits your ear. It’s gone, the air just stopped vibrating as much, while your ear drum started to.
The photon was an excitation in the electromagnetic field, and it transferred that excitation to the molecule (thanks to its electrically charged electrons). The electromagnetic field just goes back to its normal unexcited state, that is, no photon.
The “excitation” transfered was its energy, momentum, and angular momentum /spin.
A photon like everything else is made of energy. Eventually it gets converted to heat, so when it hits your eye is just gets absorbed and converted to heat/electical energy.
You said it right there, it got absorbed. It has ceased to be.
It got absorbed and that energy was enough stimulation to activate the cell on your retina, and that activation becomes a signal that is transmitted to the brain.
The photon ceases to exist. Its energy has been transferred to the electron field, which transfers to mechanical energy to move the atoms of the retinal molecule, which transfers to mechanical energy to move the atoms of the opsin protein. Changing the shape of the opsin protein causes the photoreceptor to fire. Additional stored energy from various locations (think of energy stored in the protein as “springs”) gets added at each step to make the overall process happen
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