Eli5: Does a photon really act different by looking at it? How does it know it’s being observed?
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The only photons you “see” are the ones that hit your retina and have their energy absorbed. All those photons zipping by in front of you, but missing your eyes, you don’t even know about.
The only photons you “see” are the ones that hit your retina and have their energy absorbed. All those photons zipping by in front of you, but missing your eyes, you don’t even know about.
Yes, the act of “observing” a photon does change its behavior. We discovered this by way of an experiment known as the “double slit experiment.”
It’s a bit difficult to explain without visual aids, but I’ll try and will also include a video detailing it at the end.
So you take a barrier and put two parallel slits in it, wide enough to allow something to pass through. Depending on what this something is (particle or wave), you will end up with two different patterns on the other side of the barrier. For a particle, you will have two lines of particles which neatly correspond to the slit locations with little to nothing beyond where the slits are. However if you have waves (like water, for instance) you end up with the one wave being split in half and then interfering with itself, giving you a wide pattern that repeats beyond the “boundaries” of the original slits. This is an interference pattern, and is the hallmark of waves interacting with one another.
So as an experiment, scientists fired photons at the two slits. Believing photons to be particles, they were surprised to find an interference pattern on the other side. That makes light a wave. But photons are particles, right? So how did it produce a wave pattern? So they set up equipment to record the path of the photons to see how the wave pattern was produced by particles. And in watching it happen, the pattern on the other side was changed to a particle pattern as each photon was observed passing through each slit individually.
Like I said, difficult to explain without visual aid, so [here’s a link for you.](https://youtu.be/Iuv6hY6zsd0)
For what it’s worth, I have not actually watched this video in particular. However, I like Veritasium and know he’s very good at explaining things in an easy-to-digest manner. I hope this helped!
Yes, the act of “observing” a photon does change its behavior. We discovered this by way of an experiment known as the “double slit experiment.”
It’s a bit difficult to explain without visual aids, but I’ll try and will also include a video detailing it at the end.
So you take a barrier and put two parallel slits in it, wide enough to allow something to pass through. Depending on what this something is (particle or wave), you will end up with two different patterns on the other side of the barrier. For a particle, you will have two lines of particles which neatly correspond to the slit locations with little to nothing beyond where the slits are. However if you have waves (like water, for instance) you end up with the one wave being split in half and then interfering with itself, giving you a wide pattern that repeats beyond the “boundaries” of the original slits. This is an interference pattern, and is the hallmark of waves interacting with one another.
So as an experiment, scientists fired photons at the two slits. Believing photons to be particles, they were surprised to find an interference pattern on the other side. That makes light a wave. But photons are particles, right? So how did it produce a wave pattern? So they set up equipment to record the path of the photons to see how the wave pattern was produced by particles. And in watching it happen, the pattern on the other side was changed to a particle pattern as each photon was observed passing through each slit individually.
Like I said, difficult to explain without visual aid, so [here’s a link for you.](https://youtu.be/Iuv6hY6zsd0)
For what it’s worth, I have not actually watched this video in particular. However, I like Veritasium and know he’s very good at explaining things in an easy-to-digest manner. I hope this helped!
Yes, the act of “observing” a photon does change its behavior. We discovered this by way of an experiment known as the “double slit experiment.”
It’s a bit difficult to explain without visual aids, but I’ll try and will also include a video detailing it at the end.
So you take a barrier and put two parallel slits in it, wide enough to allow something to pass through. Depending on what this something is (particle or wave), you will end up with two different patterns on the other side of the barrier. For a particle, you will have two lines of particles which neatly correspond to the slit locations with little to nothing beyond where the slits are. However if you have waves (like water, for instance) you end up with the one wave being split in half and then interfering with itself, giving you a wide pattern that repeats beyond the “boundaries” of the original slits. This is an interference pattern, and is the hallmark of waves interacting with one another.
So as an experiment, scientists fired photons at the two slits. Believing photons to be particles, they were surprised to find an interference pattern on the other side. That makes light a wave. But photons are particles, right? So how did it produce a wave pattern? So they set up equipment to record the path of the photons to see how the wave pattern was produced by particles. And in watching it happen, the pattern on the other side was changed to a particle pattern as each photon was observed passing through each slit individually.
Like I said, difficult to explain without visual aid, so [here’s a link for you.](https://youtu.be/Iuv6hY6zsd0)
For what it’s worth, I have not actually watched this video in particular. However, I like Veritasium and know he’s very good at explaining things in an easy-to-digest manner. I hope this helped!
Yes but to make it simpler you have to remember that photons correspond to a quantity of energy that is measurable and is not a ball of light flying around. So essentially you are seeing energy. Just like a wave in the ocean which is also energy, a perturbation of the water body. The wave itself does not physically exist but we can see it by its perturbation and measure its properties.
Yes but to make it simpler you have to remember that photons correspond to a quantity of energy that is measurable and is not a ball of light flying around. So essentially you are seeing energy. Just like a wave in the ocean which is also energy, a perturbation of the water body. The wave itself does not physically exist but we can see it by its perturbation and measure its properties.
Yes but to make it simpler you have to remember that photons correspond to a quantity of energy that is measurable and is not a ball of light flying around. So essentially you are seeing energy. Just like a wave in the ocean which is also energy, a perturbation of the water body. The wave itself does not physically exist but we can see it by its perturbation and measure its properties.
It doesn’t “know” its being looked at. The fact is that to observe anything, we have to bounce stuff off of it, and measure what comes back (most of the time we bounce electrons or photons off of things).
Now most things are very heavy, and electrons/photons are very light. So chucking, for example, a photon at a blue wall isn’t going to do anything to the blue wall. But when you chuck a photon at another photon, or at an electron/proton/neutron, is going to affect those tiny particles.
“Looking is touching” (dunno who said that).
Bounce a photon of an electron, and now measure the photon. You have effectively “looked at” the electron. Now do the same, but don’t measure the photon. The effect on the electron will still be the same (we can check this by bouncing a second electron off of both, and measuring both). The measuring itself isn’t really what changes things, it’s the tools we use for measuring.
It doesn’t “know” its being looked at. The fact is that to observe anything, we have to bounce stuff off of it, and measure what comes back (most of the time we bounce electrons or photons off of things).
Now most things are very heavy, and electrons/photons are very light. So chucking, for example, a photon at a blue wall isn’t going to do anything to the blue wall. But when you chuck a photon at another photon, or at an electron/proton/neutron, is going to affect those tiny particles.
“Looking is touching” (dunno who said that).
Bounce a photon of an electron, and now measure the photon. You have effectively “looked at” the electron. Now do the same, but don’t measure the photon. The effect on the electron will still be the same (we can check this by bouncing a second electron off of both, and measuring both). The measuring itself isn’t really what changes things, it’s the tools we use for measuring.
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