gib65 Posted December 31, 2022 Share Posted December 31, 2022 (edited) How does the light from distant stars get to our eyes? Maybe it's just my misunderstanding, but the odds of seeing a distant star seem astronomically low. Here's my understanding of how it works. Please let me know if I've got anything wrong. The light emitted from stars are photons. Photons travel through space as waves. These waves are no different than the waves of any other particle described by the wave function of quantum mechanics. That is to say, they describe the locations where the particle is most likely to be if one attempted to measure their location. By the time a photon from a distant star reaches my eye, the wave spans a vast amount of space. I can see the star from locations on Earth thousands of miles apart. I can even see the star from the Moon. Or from Mars. But according to quantum mechanics, when the wave function collapses, it collapses to a much more specific location. This is where I might be misunderstanding. When we see something, the light from that thing is stimulating a molecule in either a rod cell or a cone cell in the retina which triggers an electrical signal to be sent from the eye to the brain. Does this count as the wave function of the photon "collapsing"? Is the molecule in the rod/cone "absorbing" the photon? If this is right, then out of all the places and things that could have collapsed the photon's wave function throughout it's journey from the star, this one molecule in my eye happened to be the one. That seems astronomically improbable. Now, I realize the star is not just emitting one photon. It emits billions or trillions of photons every second (right?). Is this what makes up for the improbable odds? The probability still seems extremely low. The star may emit billions or trillions of photons but it is billions or trillions of miles away, so that's a huge number of things that could interact with the photon and cause it to collapse. Furthermore, it doesn't seem to matter where I stand. If I move an inch to the left, I can still see the star. If I move an inch to the right, I can still see the star. That means there are photons coming from the star for every inch of ground I could be standing on, and for every inch of ground I could be standing on, there are enough photons such that out of all the things that could cause its collapse, one of them is always guaranteed to collapse on this one molecule in my eye (and more likely, there are enough photons to collapse on several such molecules since seeing a star most likely requires several rod/cones in the eye to be stimulated). Are there really just that many photons being emitted by the stars in the sky? Or am I misunderstanding something in the above? Edited December 31, 2022 by gib65 Link to comment Share on other sites More sharing options...
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