If I'm looking at a star in the night sky that astronomers tell me is 400 light years distant, then the photons striking my rods and cones have been unchanged for 400 million years and mind boggling distance. But where do they go then? Are they converted to heat? Does an electron fly out of my eye? I want to know where that particle without mass, or that packet of energy that has maintained it's speed and properties for as long or far as there are stars to see--where does it go when it finally meets the back of my eyeballs? Has that photon died? Can a photon die?
2007-05-09 15:58:03 · 6 answers · asked by Jim N 3 in Science & Mathematics ➔ Physics
The easy anser: The photon is used up in the process to tell you you saw something.
The slightly more scientific answer (and maybe more dull fro some of you):
yeah...i dont' remember much about photoreceptors- but the energy from the photon changes the conformation (shape) of the photoreceptor molecule...there might be some electron transfer chains involved to send the signals to your brain...(I really really despised learning about cytochromes and co-enzymes....so i dont' remember it..not because it isn't cool..but because there are just too many things to remember). Changing the shape of things uses energy....so the photo is used/converted.
What I mean by conformational changes:
http://www.bmb.leeds.ac.uk/illingworth/bioc3800/cistrans.gif
and a better explanation of the process here
http://images.google.com/imgres?imgurl=http://www.chemistry.wustl.edu/~edudev/LabTutorials/Vision/images/Rodcell.jpg&imgrefurl=http://www.chemistry.wustl.edu/~edudev/LabTutorials/Vision/Vision.html&h=523&w=223&sz=32&hl=en&start=34&sig2=1ZicEO617RKZxyZmJjEJ3A&um=1&tbnid=Jl9T3XsAxE_JzM:&tbnh=131&tbnw=56&ei=AY1CRrq1B6PeiQHNmdDSCA&prev=/images%3Fq%3Drhodopsin%2Bphotons%2Belectron%2Btransfer%2Bchain%26start%3D18%26ndsp%3D18%26svnum%3D10%26um%3D1%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26hs%3D59d%26sa%3DN
2007-05-09 16:09:17 · answer #1 · answered by Seraph 2 · 1⤊ 0⤋
See the references for more detail on how the eye senses light. That photon which has been travelling for 400 years (not 400 million) is the quantum packet of electromagnetic energy. When it reaches the rod cell in your eye (the only cell type that can detect a single photon), it imparts its energy to the retinol molecule and changes its structure. That rather complex process is called visual phototransduction. It imparts its energy to that molecule and ceases to exist, or is annihilated. It's just the name for the mechanism for transfer of energy.
In that (relatively nearby) star, the fusion reaction produced a high energy helium atom. When one electron in that atom drops to a lower energy state, a photon is emitted whose energy is the difference between those two energy states. That's what found its way to your eye.
2007-05-09 18:01:09 · answer #2 · answered by Frank N 7 · 1⤊ 0⤋
No, the photon is absorbed by your eye so that you can see a picture of that really far away object.
P.S. isn't it cool that you can see the past?
2007-05-09 16:04:39 · answer #3 · answered by The Ponderer 3 · 1⤊ 0⤋
Your eye acts as a lens to concentration the gentle beam to the back of the attention, the place based on the wave-length, it is going to set off a chemical chain-reaction, culminating in brainicells firing in a undeniable way, which we perceive as coloration/gentle sensation
2016-10-31 00:09:24 · answer #4 · answered by Anonymous · 0⤊ 0⤋
i think an easier way of looking at it is by saying that the light you are seeing is a wave with properties of a wave... it just took that long for that wave to reach your eye... nothing really happens to that light outside your body... once its in your eye you perceive it... but the light and energy from that star doesn't go away once you perceive it...
2007-05-09 16:08:39 · answer #5 · answered by N TigerPaw 4 · 0⤊ 2⤋
It hits the back of your eye and energy is released that your receptors sense.
2007-05-09 16:05:34 · answer #6 · answered by Gene 7 · 0⤊ 0⤋