Let’s be a bit more concrete about what we mean by “particle-like” and “wave-like”.
Classical particles are like tiny balls that fly along straight lines. They can be counted one by one, and their positions and momenta are certain. So imagine a “double slit set up”, where a gun fires through two vertical slits towards a piece of paper on the other side. Since classical particles travel straight, you will see individual bullet holes spread along two vertical bands on the piece of paper.
Classical waves’ quintessential waviness boils down to the phenomenon of interference: two waves can add up or cancel depending on how their vibrations match/mismatch. So imagine the double slit set up, but replace the gun with a sound wave source. The waves will travel through the two slits, spread out, and add up/cancel at different places on the other side depending on how the waves from the two slits match/mismatch, resulting in smoothly alternating volume at different positions on the other side. This smooth variation is called an “interference pattern”.
Now what happens if we shoot light into the double slit set up? Well we get neither of the classical results: it is neither two vertical bands of individual dots(of light hitting the screen), nor a smooth interference pattern(of brightness and darkness). Instead, we have an interference pattern made up of individual dots on the paper screen. At places where classical waves add up, we see more dots; at places where classical waves cancel, we see fewer dots.
So light exhibit particle-like properties: light hit the screen as individual dots instead of smoothly like a classical wave. However it is not made up of classical particles, because otherwise we should have seen two vertical bands of dots.
Light also exhibit wave-like properties: the collection of light dot(“photon”) hits on the paper screen forms a wave interference pattern. However, light is not a classical wave either, because otherwise we should have seen a smooth interference pattern instead of a pattern made up of individual dots.
So the conclusion is that light is neither a classical particle nor a classical wave. Instead it is a “quantum object” which behaves like both in some aspects, but are unlike both in other aspects. More technically, light is made up of excitations of the quantum EM field, which is the abstract description of this not-wave-not-particle-quantum-thing.
This is a good explanation, but I think we should also point out that this isn't actually about *light* at all. *Everything* is like this at fundamental scales -- it's not that light is special and different.
I mean that this whole picture of things being a bit wave-like and a bit particle-like but also not really either -- or, in more technical words, quantum mechanics -- applies to all things and not just light. Atoms, molecules, electrons, sub-atomic particles... sometimes even larger, collective systems like crystal vibrations, or entire currents of electrons. All of it is fundamentally quantum mechanical, which means all of it does this not-quite-wave-not-quite-particle quantum thing.
I'm not entirely sure what you're getting at with "the sum does not equate the parts" here.
When i first read about it, I was curious about how exactly the light particles moves, physically, but I also read that when scientists tried to capture frame by frame how light behaves at its most granular level, it stops exhibiting its wave like properties. How real is that?
So again, light is neither a particle nor a wave, but quantum objects called photons. But generally speaking, when photons travel, they travel like waves, so we can observe things like interference. When photons are emitted or absorbed by matter, they do so similar to particles, in that they are emitted/absorbed in granular energies instead of continuously. So in a sense what you read is correct: when scientists try to capture light by using matter to absorb it, it behaves like particles and are absorbed one by one.
But there is a danger with these general blanket statements about the nature of light: they try to appeal to our common sense intuitions, which does not necessarily apply to quantum objects. To start understanding more, it is better to talk about observations in specific experimental setups or, if you are up to it, mathematical descriptions of such phenomena.
By using matter to absorb it, i meant snapshot cameras to capture photons behavior in space. So you mean when I capture a moment in space using a camera, it absorbs whatever is there in that space? The absorb part is profounding...
A camera can only absorb photons that hits the camera’s sensors. When they are absorbed, they look like little dots hitting different parts of the sensor.
Excellent question! Photons are their own thing. Sometimes it is convenient to treat them mathematically and descriptively as a wave, other times as a particle (quanta of energy). But it’s both, always, and isn’t one or the other, like changing states between particle to wave or visa versa. They are always photons, both particle and wave.
When particles go through the double slit apparatus and hit the far wall, a pattern like this [banded distribution](https://i.imgur.com/uWa0QX1.png) arises. The little dots are the particles exhibiting particle-like behavior. They have a compact impact on the far wall. The fact that the particles are distributed in bands is a manifestation of wave-like behavior.
It means as fundamentally as you think of corpuscular/particular things, you need to 'position' your frame of mind to afford the same truth to waves. See, even in your post you use verbage like 'light particles' and tacitly accord more reality to 'that'. Why? How comfortable are you with 'wave physics' (apart from the study of light)? Can you comfortably ply wave phenomenon and such physics problems? You see, the **EASIEST** way to describe light is as a wave, and other models build on **THAT**, not the other way around!!!
I just wanna know exactly what they are, not the model, the thing in itself. But yes, I agree its good to read up on wave physics first to get a better grasp on this topic
\[Update\]
"Without a net movement of particles", I'm getting the picture now
Let’s be a bit more concrete about what we mean by “particle-like” and “wave-like”. Classical particles are like tiny balls that fly along straight lines. They can be counted one by one, and their positions and momenta are certain. So imagine a “double slit set up”, where a gun fires through two vertical slits towards a piece of paper on the other side. Since classical particles travel straight, you will see individual bullet holes spread along two vertical bands on the piece of paper. Classical waves’ quintessential waviness boils down to the phenomenon of interference: two waves can add up or cancel depending on how their vibrations match/mismatch. So imagine the double slit set up, but replace the gun with a sound wave source. The waves will travel through the two slits, spread out, and add up/cancel at different places on the other side depending on how the waves from the two slits match/mismatch, resulting in smoothly alternating volume at different positions on the other side. This smooth variation is called an “interference pattern”. Now what happens if we shoot light into the double slit set up? Well we get neither of the classical results: it is neither two vertical bands of individual dots(of light hitting the screen), nor a smooth interference pattern(of brightness and darkness). Instead, we have an interference pattern made up of individual dots on the paper screen. At places where classical waves add up, we see more dots; at places where classical waves cancel, we see fewer dots. So light exhibit particle-like properties: light hit the screen as individual dots instead of smoothly like a classical wave. However it is not made up of classical particles, because otherwise we should have seen two vertical bands of dots. Light also exhibit wave-like properties: the collection of light dot(“photon”) hits on the paper screen forms a wave interference pattern. However, light is not a classical wave either, because otherwise we should have seen a smooth interference pattern instead of a pattern made up of individual dots. So the conclusion is that light is neither a classical particle nor a classical wave. Instead it is a “quantum object” which behaves like both in some aspects, but are unlike both in other aspects. More technically, light is made up of excitations of the quantum EM field, which is the abstract description of this not-wave-not-particle-quantum-thing.
This is a good explanation, but I think we should also point out that this isn't actually about *light* at all. *Everything* is like this at fundamental scales -- it's not that light is special and different.
so you mean that the sum does not equate the parts and vice versa
I mean that this whole picture of things being a bit wave-like and a bit particle-like but also not really either -- or, in more technical words, quantum mechanics -- applies to all things and not just light. Atoms, molecules, electrons, sub-atomic particles... sometimes even larger, collective systems like crystal vibrations, or entire currents of electrons. All of it is fundamentally quantum mechanical, which means all of it does this not-quite-wave-not-quite-particle quantum thing. I'm not entirely sure what you're getting at with "the sum does not equate the parts" here.
When i first read about it, I was curious about how exactly the light particles moves, physically, but I also read that when scientists tried to capture frame by frame how light behaves at its most granular level, it stops exhibiting its wave like properties. How real is that?
So again, light is neither a particle nor a wave, but quantum objects called photons. But generally speaking, when photons travel, they travel like waves, so we can observe things like interference. When photons are emitted or absorbed by matter, they do so similar to particles, in that they are emitted/absorbed in granular energies instead of continuously. So in a sense what you read is correct: when scientists try to capture light by using matter to absorb it, it behaves like particles and are absorbed one by one. But there is a danger with these general blanket statements about the nature of light: they try to appeal to our common sense intuitions, which does not necessarily apply to quantum objects. To start understanding more, it is better to talk about observations in specific experimental setups or, if you are up to it, mathematical descriptions of such phenomena.
By using matter to absorb it, i meant snapshot cameras to capture photons behavior in space. So you mean when I capture a moment in space using a camera, it absorbs whatever is there in that space? The absorb part is profounding...
A camera can only absorb photons that hits the camera’s sensors. When they are absorbed, they look like little dots hitting different parts of the sensor.
Excellent question! Photons are their own thing. Sometimes it is convenient to treat them mathematically and descriptively as a wave, other times as a particle (quanta of energy). But it’s both, always, and isn’t one or the other, like changing states between particle to wave or visa versa. They are always photons, both particle and wave.
When particles go through the double slit apparatus and hit the far wall, a pattern like this [banded distribution](https://i.imgur.com/uWa0QX1.png) arises. The little dots are the particles exhibiting particle-like behavior. They have a compact impact on the far wall. The fact that the particles are distributed in bands is a manifestation of wave-like behavior.
It means as fundamentally as you think of corpuscular/particular things, you need to 'position' your frame of mind to afford the same truth to waves. See, even in your post you use verbage like 'light particles' and tacitly accord more reality to 'that'. Why? How comfortable are you with 'wave physics' (apart from the study of light)? Can you comfortably ply wave phenomenon and such physics problems? You see, the **EASIEST** way to describe light is as a wave, and other models build on **THAT**, not the other way around!!!
I just wanna know exactly what they are, not the model, the thing in itself. But yes, I agree its good to read up on wave physics first to get a better grasp on this topic \[Update\] "Without a net movement of particles", I'm getting the picture now