What do you consider a particle?
Something like a dust particle, perhaps?
Something tiny, localised to a point that follows a precise trajectory?
Something that you can attach labels to, like position and momentum, where the labels represent various properties of the particle?
If the above definitions sound reasonable, then no, photons are not particles. At least, they are not particles as defined above.
We need to change our definition of what constitutes a particle.
How about: Particles participate in local interactions.
That's a very restricted definition of what a particle is. It only pertains to
What do you consider a particle?
Something like a dust particle, perhaps?
Something tiny, localised to a point that follows a precise trajectory?
Something that you can attach labels to, like position and momentum, where the labels represent various properties of the particle?
If the above definitions sound reasonable, then no, photons are not particles. At least, they are not particles as defined above.
We need to change our definition of what constitutes a particle.
How about: Particles participate in local interactions.
That's a very restricted definition of what a particle is. It only pertains to interactions. It makes no claims about the so-called particles between interactions.
Under this restricted definition, photons are particles.
This is why quantum theory is not so intuitive. Most people associate particles with the properties I first listed. They cannot reject such properties and just accept the restricted property. Furthermore, the consequences of accepting only the restricted property are profound. Moreover, this is the definition you need to adopt with all quantum particles. This is ultimately encapsulated in the catch-all term, wave-particle duality.
Photons are force-carrying gauge bosons, along with gluons, the W and Z particles, and the Higgs. Unlike fermions, they can exist in any numbers for any given quantum state.
Like the gluon, the photon has no mass, but I have not heard of either of them not being “elementary particles.”
Irrelevant footnote: I see this chart with a tinge of regret. When I worked in the field (a half century or so ago), the generation III quarks were not called “top” and “bottom” but Truth and Beauty. I wonder if the purists will redub Strange and Charm as well, to zenith and nadir, or some other dumb aid to rememb
Photons are force-carrying gauge bosons, along with gluons, the W and Z particles, and the Higgs. Unlike fermions, they can exist in any numbers for any given quantum state.
Like the gluon, the photon has no mass, but I have not heard of either of them not being “elementary particles.”
Irrelevant footnote: I see this chart with a tinge of regret. When I worked in the field (a half century or so ago), the generation III quarks were not called “top” and “bottom” but Truth and Beauty. I wonder if the purists will redub Strange and Charm as well, to zenith and nadir, or some other dumb aid to remembering which is which.
Short answer: Yes.
Longer answer: The photon is a unit excitation (quantum) of the electromagnetic field. The electromagnetic field satisfies Maxwell's (wave) equations, which suggests that the photon is a wave. However, when you interact with the electromagnetic field, the interaction may be spatially localized, allowing the photon to appear as a particle.
The same is true for other particles, such as the electron. Which may explain why J. J. Thompson received the 1906 physics Nobel prize for discovering the electron particle; only to have his son, George Paget Thompson, become the recipient of
Short answer: Yes.
Longer answer: The photon is a unit excitation (quantum) of the electromagnetic field. The electromagnetic field satisfies Maxwell's (wave) equations, which suggests that the photon is a wave. However, when you interact with the electromagnetic field, the interaction may be spatially localized, allowing the photon to appear as a particle.
The same is true for other particles, such as the electron. Which may explain why J. J. Thompson received the 1906 physics Nobel prize for discovering the electron particle; only to have his son, George Paget Thompson, become the recipient of the 1937 physics Nobel for showing the wave properties of the electron.
Which takes me back to my short answer: Yes.
Yes, according to the way the teem is now used.
In 19th century classical physics there were a lot of terms for things that were thought to behave in a certain way, but where the behavior is now understood due especially to relativity and quantum mechanics. One has a decision to make as to what terms to use after the paradigm shift. One option is to come up with all new terms, but this probably would have made physics harder to learn.
Reusing terminology runs the risk of causing confusion also, but can help you notice analogies. Some principles remain valid and there are a lot of useful analogie
Yes, according to the way the teem is now used.
In 19th century classical physics there were a lot of terms for things that were thought to behave in a certain way, but where the behavior is now understood due especially to relativity and quantum mechanics. One has a decision to make as to what terms to use after the paradigm shift. One option is to come up with all new terms, but this probably would have made physics harder to learn.
Reusing terminology runs the risk of causing confusion also, but can help you notice analogies. Some principles remain valid and there are a lot of useful analogies. Classical physics is still important as an approximation to the better approximation provided by current physics.
The way that “particle” has been redefined is a cade of this. The phrase “wave-particle duality” helps to confuse this by making it sound like quantum mechanics says particles are only particles part of the time. But physicists decided to keep calling the matter particles like electrons particles. The massless particles like photons have nearly all the same attributes, and are also called particles.
The languages of “particles” and “fields” are alternative ways to talk about the same phenomena, but different aspects of it.
The main thing about what are now called particles that is unlike the way people used to think of particles is that they don't have an exactly defined position. But nothing does, as far as we know, including electrons. If you interact with them in a way that is sensitive to their position (like making them hit a screen) you get behavior like they were localized to one spot. This last feature is perhaps one of the hallmarks of being a particle.
According to quantum mechanics, they act like waves, but according to quantum mechanics everything does.
Waves like sound waves act enough like particles that they can be treated as a collection of quasiparticles called phonons. Physicists have opted to use the term quasiparticle that emphasizes the similarities with ordinary particles.
Sort of. They really aren’t particles like we know in the everyday macroscopic world. They are quantum particles. And by that we mean, they aren’t really in one place or in one state. They have a smeared out existence that really doesn’t make sense if you think of them like particles (tiny billiard balls).
Feynman was asked, ”Well if they aren’t like billiard balls, what are they like?”
He said, “I can’t answer that. I can’t tell you what they are like because they aren’t like anything you know of.”
You simply don’t know of things that have an existence smeared out in space, quantum state, and ti
Sort of. They really aren’t particles like we know in the everyday macroscopic world. They are quantum particles. And by that we mean, they aren’t really in one place or in one state. They have a smeared out existence that really doesn’t make sense if you think of them like particles (tiny billiard balls).
Feynman was asked, ”Well if they aren’t like billiard balls, what are they like?”
He said, “I can’t answer that. I can’t tell you what they are like because they aren’t like anything you know of.”
You simply don’t know of things that have an existence smeared out in space, quantum state, and time. And that leads to what we think of as contradictions, like the double slit experiment.
So, if you mean particles that you understand, then no, photons are not that kind of particle.
Is it a particle…? Is it a wave…? It’s, it’s… Superboson!
But seriously: the question is not so much “What is it”, but “how does it behave”. (It has both particle properties and wave properties. In some respects, it behaves as if it is a particle, and in some other respects, it behaves like a wave.)
Science is not about what things “ARE” -that would be truth business. And at its fundaments, that’s unknowable. “Stuff” is what we call a bunch of particles. But what about the particles themselves? What are they made of? (Is it even “made of”…?) Whatever it is: it ain’t “stuff”. It is what it is. An
Is it a particle…? Is it a wave…? It’s, it’s… Superboson!
But seriously: the question is not so much “What is it”, but “how does it behave”. (It has both particle properties and wave properties. In some respects, it behaves as if it is a particle, and in some other respects, it behaves like a wave.)
Science is not about what things “ARE” -that would be truth business. And at its fundaments, that’s unknowable. “Stuff” is what we call a bunch of particles. But what about the particles themselves? What are they made of? (Is it even “made of”…?) Whatever it is: it ain’t “stuff”. It is what it is. And its nature is alien to us.
Science describes the *behavior* of reality, and it looks for characteristic behavior. For that, science observes reality, and seeks to come up with models that describe and explain the behavior, and with which other behavior can be predicted. And the best model for some phenomenon, at any given time (typically, well-defined predictions turning out out be accurate or more accurate than other models- increases the status of a scientific model. When Einstein’s general relativity model appeared to be able to very accurately account for the mysterious precession of the orbit of Mercury, it proved to be more accurate than Newton’s model of gravity: Newton’s equations fail to explain this particular phenomenon, but it served well for the rest -and it still does- because for anything non-relativistic, it IS as good as spot on, and it’s easier to use than GR), is awarded the ultimate status: the theory of X. And when a better model comes along, it becomes the new champ. It’s tentative, and as a result, improvement is possible.
Science is not a matter of being “true”, and therefore it is not something to “believe” or to “believe in” -that would be religion. Science is about actually *understanding* how reality works. That’s a completely different ballgame. It has nothing to do with mere faith (belief based on proclamation - pontification) either. Theists sometimes like to belittle science -for instance for NOT being immutable, iow precisely for being able to improve(!)- by calling it… a *religion!!!* Priceless, huh?
TL;DR: Photons are particles, though the modern term "particle" shares very few properties with the classical particle.
The photon is a particle. In modern physics the term does not mean that it's a small ball or anything even close to that. Particle, in modern physics, is synonymous with field quantum. If you ever catch yourself thinking about little balls when you hear the word particle, instead, try to substitute it with "field quantum" and realize that you (probably) have no idea what that is and how it "should" behave!
Bonus: This substitution could help you be less surprised when field qua
TL;DR: Photons are particles, though the modern term "particle" shares very few properties with the classical particle.
The photon is a particle. In modern physics the term does not mean that it's a small ball or anything even close to that. Particle, in modern physics, is synonymous with field quantum. If you ever catch yourself thinking about little balls when you hear the word particle, instead, try to substitute it with "field quantum" and realize that you (probably) have no idea what that is and how it "should" behave!
Bonus: This substitution could help you be less surprised when field quanta behave in interesting ways, like tunneling through potentials that a classical particle wouldn't be able to pass through. That's a property of field quanta, and suddenly you know a tiny bit more about what defines them, instead of being confused because "solid balls pass through walls," which is not correct.
So, the particles commonly called photons are field quanta of the EM-field. They sometimes appear localized and sometimes non-localized. Or in other terms, sometimes they are particle-like (in the classical particle sense) and sometimes wave-like. Note that the "appear" and "-like" parts are important. One could even model them like waves sometimes and like classical particles other times, but each such model will ultimately fail to describe photons in all contexts.
Off-topic, though useful when thinking about QM, the following article describes a useful approach to physics:
Think Like Reality
Short excerpt:
Reality has been around since long before you showed up. Don't go calling it nasty names like "bizarre" or "incredible". The universe was propagating complex amplitudes through configuration space for ten billion years before life ever emerged on Earth. Quantum physics is not "weird". You are weird. You have the absolutely bizarre idea that reality ought to consist of little billiard balls bopping around, when in fact reality is a perfectly normal cloud of complex amplitude in configuration space. This is your problem, not reality's, and you are the one who needs to change.
In quantum mechanics, both. The particle and wave nature are entwined.
But if this bothers you, there are a number of ‘classical approximations’ that you can work with. They never explain the results of all experiments. But they are useful under restricted circumstances.
Let us start with an ‘all wave’ approximation. Assume that light is not made of true particles.
One approximation is that a photon is a wave packet with a minimum energy.
Look up:
Fourier transform
Wave packet
Wave packets are a superpositions of sinusoidal waves where most or all of the energy of these waves is restricted to a small
In quantum mechanics, both. The particle and wave nature are entwined.
But if this bothers you, there are a number of ‘classical approximations’ that you can work with. They never explain the results of all experiments. But they are useful under restricted circumstances.
Let us start with an ‘all wave’ approximation. Assume that light is not made of true particles.
One approximation is that a photon is a wave packet with a minimum energy.
Look up:
Fourier transform
Wave packet
Wave packets are a superpositions of sinusoidal waves where most or all of the energy of these waves is restricted to a small volume.
You can build up a large wave packet by superimposing smaller packet in space and time.
This is an all wave model. Wave packets act like particles. But on a fundamental level, they are constructions of wave.
One problem with this ‘classical approximation’ is the ‘minimal energy’. Classical waves don’t have a minimal energy.
Please note this is an approximation. You can’t explain entanglement this way, for instance.
- Imagine that everything in the universe (such as a photon) is made up of little chunks of energy.
- Imagine that each chunk is free to be anywhere in the universe at any given moment - all at once. Imagine it can be in two, three or a hundred places at once.
- However, because you are more likely to find a given chunk in some situations and less likely to find it in others - it appears to "exist more firmly" in certain situations - just like a ripple on a pond has a strong peak that attracts your eye as it moves along the water.
- So, if you "pin a particle down" by looking at the "peak of the wave" i
- Imagine that everything in the universe (such as a photon) is made up of little chunks of energy.
- Imagine that each chunk is free to be anywhere in the universe at any given moment - all at once. Imagine it can be in two, three or a hundred places at once.
- However, because you are more likely to find a given chunk in some situations and less likely to find it in others - it appears to "exist more firmly" in certain situations - just like a ripple on a pond has a strong peak that attracts your eye as it moves along the water.
- So, if you "pin a particle down" by looking at the "peak of the wave" it looks like a particle. But, if you "zoom out" a bit and look at it "in a more relaxed way" you can see it is a wave and you can catch it looking and acting like a wave.
The photon with the image we get from the particle is not really a particle. Consider that photon is not a solid spherical, even a point – like particle. The historical problem of light was the wave and particle properties of light that had been raised since Newton and Huygens. In 1807, Thomas Young showed light behaves like a wave. In 1864, James Clerk Maxwell established "Dynamical Theory of the Electromagnetic Field" and showed light is an electromagnetic wave. [1]
In 1900, Max Planck assumed that the radiation energy is emitted, not continuously, but rather in discrete packets called quanta
The photon with the image we get from the particle is not really a particle. Consider that photon is not a solid spherical, even a point – like particle. The historical problem of light was the wave and particle properties of light that had been raised since Newton and Huygens. In 1807, Thomas Young showed light behaves like a wave. In 1864, James Clerk Maxwell established "Dynamical Theory of the Electromagnetic Field" and showed light is an electromagnetic wave. [1]
In 1900, Max Planck assumed that the radiation energy is emitted, not continuously, but rather in discrete packets called quanta. The energy E of the quantum is related to the frequency as E=hf , Where h is universal Planck’s constant. [2]
“In 1902 Lenard discovered that energy of electrons in photoeffect does not depend on the intensity of light, while it depends on the wavelength of the latter”. [3]
In 1905, “Einstein has shown that all experiments related to the black body radiation, photoluminescence and production of cathode rays by ultraviolet light can be explained by the quanta of light”. [3]
“In 1905, Einstein attempted to resolve the duality of atoms and waves by demonstrating that part of Planck's formula can arise only from the hypothesis that electromagnetic radiation behaves as if it actually consists of individual "quanta" of energy. The continuous waves of Maxwell's equations, which had been confirmed experimentally, could be considered only averages over myriads of tiny light quanta, essentially "atoms" of light. With his light quantum hypothesis Einstein could not only derive part of Planck's formula but also account directly for certain hitherto inexplicable phenomena. Foremost among them was the photoelectric effect: the ejection of electrons from a metal when irradiated by light”. [4]
“There are still many puzzling aspects of the nature of light”. [5] Einstein wrote in 1951: “All these fifty years of pondering have not brought me any closer to answering the question, what are light quanta?” [3]
Seems light is a set of photons propagating through space as electromagnetic waves.
1 - Hamamatsu, History of research on light, Photon terrace
2 - M. Planck, On the Law of the Energy Distribution in the Normal Spectrum, Ann. Phys., 4, 553, 1901
3 - L.B. Okun, Photon: history, mass, charge, ArXiv, 2006
The honest answer is, both and none. This ambiguous answer is due to the nature of quantum physics.
The "photon" light particle concept is based on electromagnetic properties of Maxwell's equations, and the photon is an electromagnetic wave-packet. For this reason, the energy of the photon can be indicated by frequency as E=hf. In quantum mechanics, a photon is an unstructured point-like particle.
Even a century after the emergence and acceptance of quantum mechanics, the physical nature of particles and waves is still under dispute.
Consider the two opposing approaches below:
“Are the fundamental
The honest answer is, both and none. This ambiguous answer is due to the nature of quantum physics.
The "photon" light particle concept is based on electromagnetic properties of Maxwell's equations, and the photon is an electromagnetic wave-packet. For this reason, the energy of the photon can be indicated by frequency as E=hf. In quantum mechanics, a photon is an unstructured point-like particle.
Even a century after the emergence and acceptance of quantum mechanics, the physical nature of particles and waves is still under dispute.
Consider the two opposing approaches below:
“Are the fundamental constituents fields or particles? As this paper shows, experiment and theory imply unbounded fields, not bounded particles, are fundamental”. [1]
“I arrive at the conclusion that in addition to there being no particles, there are not even fields! The fields of QFT are operators”. [2]
Generally, we have almost the same understanding and imagination of large objects (at the level of molecules and larger). But in the case of subatomic particles, there is no clearly defined and visualized concept, and there are many uncertainties, especially in the case of photon and graviton. Therefore, any theory offers certain understanding (such as loop and string) of these particles. However, we are using the particles for graviton and photon without any imagination of them. Read more Hossein Javadi's answer to What do you think of this statement, “There are no fields in nature, only particles. Fields are figments of theorist’s imaginations.”?
1 - Art Hobson, There are no particles, there are only fields, American Journal of Physics 81, 211 (2013); https://doi.org/10.1119/1.4789885
2 - Robert J. Sciamanda, THERE ARE NO PARTICLES, AND THERE ARE NO FIELDS, American Journal of Physics 81, 645 (2013); https://doi.org/10.1119/1.4812316
It all dependes on way you observe it. Imagine you can only observe an object by it’s shadow. You shine a light on it and the shadow is a perfect circle.
You move the light to a different position and now the shadow is a triangle! Straight lines with sharp angles! The previous shadow had no straight lines and certainly no angles!
That is the duality of the photon, if you do experiments one way the ONLY explanation for the results is that the photon is a particle.
Other experiments the results show that the photon HAS to be a wave.
Which one is the correct view? The answer is, it all depends on how
It all dependes on way you observe it. Imagine you can only observe an object by it’s shadow. You shine a light on it and the shadow is a perfect circle.
You move the light to a different position and now the shadow is a triangle! Straight lines with sharp angles! The previous shadow had no straight lines and certainly no angles!
That is the duality of the photon, if you do experiments one way the ONLY explanation for the results is that the photon is a particle.
Other experiments the results show that the photon HAS to be a wave.
Which one is the correct view? The answer is, it all depends on how you are looking at it!
Back to the shadow, the object that casts the two remarkably different shadows is a cone. From the side it is a triangle, from above it is a circle.
Hi! Thank You for Your great Qustion
Light can be described both as a wave and as a particle. There are two experiments in particular that have revealed the dual nature of light.
When we’re thinking of light as being made of of particles, these particles are called “photons”. Photons have no mass, and each one carries a specific amount of energy. Meanwhile, when we think about light propagating as waves, these are waves of electromagnetic radiation. Other examples of electromagnetic radiation include X-rays and ultraviolet radiation.
It’s worth remembering light — regardless of whether it’s behav
Hi! Thank You for Your great Qustion
Light can be described both as a wave and as a particle. There are two experiments in particular that have revealed the dual nature of light.
When we’re thinking of light as being made of of particles, these particles are called “photons”. Photons have no mass, and each one carries a specific amount of energy. Meanwhile, when we think about light propagating as waves, these are waves of electromagnetic radiation. Other examples of electromagnetic radiation include X-rays and ultraviolet radiation.
It’s worth remembering light — regardless of whether it’s behaving like a wave or particles — will always travel at roughly 300,000 kilometres per second. The speed of light as it travels through space (or another vacuum) is the fastest phenomenon in the universe, as far as we know.
The double-slit experiment
Imagine you have a bucket of tennis balls. Two metres in front of you is a solid panel with two holes in it. A metre behind that panel is a wall. You dip each ball in red paint and throw it at one hole, and then the other. A successful throw will leave a red mark on the wall behind, leaving a specific pattern of roundish dots.
Now, suppose you shoot a single beam of light at the same panel with holes in it, on the same trajectory as the tennis balls. If light is a beam of particles, or in other words a beam of photons, you would expect to see a similar pattern to that made by the tennis balls where the light particles strike the wall.
That, however, isn’t what you see. Instead, you see a complex pattern of stripes. Why?
This is because light, in this situation, acts like a wave. When we shoot a beam of light through the holes, it breaks into two beams. The two resulting waves then interfere with each other to become either stronger (constructive interference) or weaker (destructive interference).
Now imagine there’s also a boat in the pond with Lego soldiers aboard. As the ripples reach the boat, they have the potential to throw the soldiers off. The more energy the ripples carry, the greater the force with which the soldiers will be thrown off.
And since each ripple can potentially throw off a soldier, the more ripples that reach the boat within a certain time limit, the more soldiers we can expect will be thrown off during that time.
Light waves also have peaks and troughs and therefore ripple in a similar manner. In the wave theory of light, these oscillations are linked to two properties of light: intensity and frequency.
Simply put, the frequency of a light wave is the number of peaks that pass a point in space in a given period (like when a certain number of ripples strike the boat within a specific time). The intensity corresponds to the energy of the wave (like the energy carried by each ripple in our pond).
Scientists in the 19th century pictured electrons on a sheet of metal as behaving similarly to the Lego soldiers on our raft. When light strikes the metal, the ripples should throw the electrons off.
The greater the intensity (the energy of the ripples) the faster the electrons will fly off, they thought. The higher the frequency within a specific time period, the greater the number of electrons that will get thrown off during that time — right?
What we actually see is the complete opposite! It’s the frequency of the light hitting the metal which determines the speed of the electrons as they shoot off. Meanwhile the intensity of the light, or how much energy it carries, actually determines the number of electrons flying away.
Einstein’s explanation
Einstein had a great explanation for this peculiar observation. He hypothesised light is made of particles, and is in fact not a wave. He then linked the intensity of light to the number of photons in a beam, and the frequency of light to how much energy each photon carries.
When more photons are shot at the metal (greater intensity), there are more collisions between the photons and electrons, so a greater number of electrons are emitted. Thus, the intensity of the light determines the number of electrons emitted, rather than the speed with which they fly off.
When light’s frequency is increased and each photon carries more energy, then each electron also takes more energy from the collision — and will therefore fly off with more speed.
This explanation earned Einstein a Nobel Prize in 1921.
Wave or particle?
Considering all of the above, one question remains: is light a wave that sometimes looks like a particle, or a particle that sometimes looks like a wave? There is disagreement about this.
My money is on light being a wave that displays particle-like properties under certain conditions. But this remains a controversial issue — one that takes us into the exciting realm of quantum mechanics. I encourage you to dig deeper and make up your own mind!
“Is light a wave, particle, or wave of particles?”
That’s one of those questions we don’t have a really good answer for yet.
Light behaves like a particle, and light also behaves like a wave. A single photon moves at the speed of light in straight lines like a bullet, but it also sort of “vibrates” with a frequency related to it’s energy level and it’s color.
But there’s that darn Heisenberg uncertainty thing that makes it impossible to separate out a single photon and study it. The moment we do that, it stops being a wave and becomes a particle. We can’t look at any of it’s wave-like properties.
“Is light a wave, particle, or wave of particles?”
That’s one of those questions we don’t have a really good answer for yet.
Light behaves like a particle, and light also behaves like a wave. A single photon moves at the speed of light in straight lines like a bullet, but it also sort of “vibrates” with a frequency related to it’s energy level and it’s color.
But there’s that darn Heisenberg uncertainty thing that makes it impossible to separate out a single photon and study it. The moment we do that, it stops being a wave and becomes a particle. We can’t look at any of it’s wave-like properties. But then, if we do study it’s wave-like properties, then we can’t learn anything about it’s particle-like properties either. We can’t know it as both a wave and a particle.
So, it’s not really “a wave of particles,” because it can’t be both. It IS both, but they can’t be both at the same time. They switch depending on how we observe them.
It’s weird and complicated, and I don’t entirely understand it myself. But that’s how it works.
No, it’s perfectly clear what light is. Light is energy propagating in the fundamental quantized electromagnetic field in the form of momentum. The fundamental quantized electromagnetic field is the three-dimensional matrix structure of its elementary particles of photons.
The photons of the field act like particles but the entire field exhibits wave-like behavior as the electromagnetic energy propagates through it.
The field is an immaterial medium so it is not physically waving. Only if we charted the oscillating field values on a graph would we see a wave pattern on the graph.
No, it’s perfectly clear what light is. Light is energy propagating in the fundamental quantized electromagnetic field in the form of momentum. The fundamental quantized electromagnetic field is the three-dimensional matrix structure of its elementary particles of photons.
The photons of the field act like particles but the entire field exhibits wave-like behavior as the electromagnetic energy propagates through it.
The field is an immaterial medium so it is not physically waving. Only if we charted the oscillating field values on a graph would we see a wave pattern on the graph.
Probably the best description of physical reality at quantum scale is in QFT, and it does not talk about particles or waves; it talks about quantum excitations of the field. There are four fundamental forces of nature identified by physics (so far) and they interact (which is why there is a search for a unifying theory, but that’s another story) to generate fields. The interaction is dynamic which makes the field oscillate. The peaks of those oscillations are the quantum excitations of the field. Fields interact to generate all observable phenomena; the field interactions are conducted by thos
Probably the best description of physical reality at quantum scale is in QFT, and it does not talk about particles or waves; it talks about quantum excitations of the field. There are four fundamental forces of nature identified by physics (so far) and they interact (which is why there is a search for a unifying theory, but that’s another story) to generate fields. The interaction is dynamic which makes the field oscillate. The peaks of those oscillations are the quantum excitations of the field. Fields interact to generate all observable phenomena; the field interactions are conducted by those quantum excitations of the field.
Photons are quantum excitations of the unbound EM field. They are not particles, nor are they waves. A “real” wave, that is, a classical wave like a wave on water, has an amplitude but it does not have a wavelength or a frequency; to derive those values there must be at least two waves. Not in quantum theory; a single photon “has” a frequency and associated wavelength. Actually, it doesn’t really, it only has an invariant velocity and a measure of kinetic energy. When a photon’s kinetic energy interacts with a quantum excitation of the bound EM field surrounding an atomic nucleus in an atom composing a molecule in a detector, it boosts the amplitude of the field’s oscillations and that boost is registered as a certain frequency with an associated wavelength. The photon itself only has a measure of kinetic energy; the field it interacted with was already oscillating when the photon arrived. On account of the oscillating field, it is assumed that photons are oscillating. Photons are not geometric waves like waves on water. They are only statistical waves; their behavior can be seen as wave-like as the distribution of the statistical probabilities of that behavior can be plotted on a graph and that plot looks like a wave. A real, physical wave only has an amplitude; it takes at least two waves to know the wavelength and frequency.
There was a mathematician named Dr. Eckhart Stein (taught at Konstanz U. in Germany) who thought he could illustrate the geometry of photons and electrons, and I made a video based on his ideas:
Neither. Light is not a particle and not a wave.
With this topic the word “particle” causes confusion. There are just too many meanings of that word. So I am going to use the word “marble” instead of particle here.
Light cannot be a wave because waves do not have marble properties and light cannot be a marble because marbles do not(*) have wave properties. Light (a photon) is something else.
(*): yes, yes. Quantum mechanics says they do, jada jada. But that is why I use “marble” here and not “particle”. “Marble” here is only about the particle-ness of particles, so excluding QM per-definition.
The
Neither. Light is not a particle and not a wave.
With this topic the word “particle” causes confusion. There are just too many meanings of that word. So I am going to use the word “marble” instead of particle here.
Light cannot be a wave because waves do not have marble properties and light cannot be a marble because marbles do not(*) have wave properties. Light (a photon) is something else.
(*): yes, yes. Quantum mechanics says they do, jada jada. But that is why I use “marble” here and not “particle”. “Marble” here is only about the particle-ness of particles, so excluding QM per-definition.
The way I make sense of this is that I think that a photon is a quantized packet of energy. More specific, an electromagnetic packet. A packet of electric and magnetic effects that induce each other like a kind of relay race. This packet is localized in space like a marble but fundamentally consists of only electric and magnetic effects with induce each other at some natural frequency where this frequency is responsible for the waviness.
This packet is relatively stable because of energy preservation and quantum effects (you cannot have half a photon). You could say this packet has a kind of cohesion. So it takes some effort to absorb, stop or convert a photon into something else. This “effort” is then part of the marble-ness and the frequency causes the waviness.
So depending how you look at a photon, you can find effects caused by its marble-ness and/or its waviness.
You have to define actually in order to answer this question.
In quantum mechanics, entities such as electrons, photons etc have a reality*, but it is not the same type of reality that, say, buses or footballs possess.
Photons possess energy and momentum, like a ball or a bus; however for a photon the Heisenberg uncertainty principle means these properties cannot be assigned simultaneously with time and energy respectively.
A key point of quantum mechanics is that particles are described by a wavefunction that exhibits interference properties- no classical particle has this property.
A photon is a
You have to define actually in order to answer this question.
In quantum mechanics, entities such as electrons, photons etc have a reality*, but it is not the same type of reality that, say, buses or footballs possess.
Photons possess energy and momentum, like a ball or a bus; however for a photon the Heisenberg uncertainty principle means these properties cannot be assigned simultaneously with time and energy respectively.
A key point of quantum mechanics is that particles are described by a wavefunction that exhibits interference properties- no classical particle has this property.
A photon is actually a particle if an electron is because both are quantum entities with wave and particle properties, depending on what you choose to measure.
But neither is like a tiny ball, or anything that can be imagined. Some would argue that they are ontologically different from classical particles.
I am sorry that that is confusing, but that is just how nature is!
Note
*I am following Karl Popper’s definition of reality from The Self and Its Brain
That is, something is real if it can affect a world 1 object such as a football. A photon can be detected by a sensor to activate a switch that makes a machine kick a ball so is “real”
It means that the phenomenon we call photons have behavior that in some ways is wavelike (can exhibit constructive and destructive interference, for example) and in other ways is particle like (when a photon strikes a photographic plate, for example, it always does so at a specific location with a specific amount of energy).
A better way to think about this is to note that all quantum level phenome
It means that the phenomenon we call photons have behavior that in some ways is wavelike (can exhibit constructive and destructive interference, for example) and in other ways is particle like (when a photon strikes a photographic plate, for example, it always does so at a specific location with a specific amount of energy).
A better way to think about this is to note that all quantum level phenomena have this behavior. The detectable interactions are always at specific locations and involve a specific amount of energy - detections behave like particles...
Whenever you fire light of sufficiently low intensity at a detector you find it gives single point activation, single clicks, or it activates one only pixel. That indicates that the energy is confined to a very limited volume, and we call something that does that a particle, or in this case, a photon.
However, if you shine light on a surface, such as water, you will find some is reflected and some is refracted. That is a wave property. Further, if you send your low-intensity light through the two-slit experiment you get the interference effect characteristic of waves, even though the detector a
Whenever you fire light of sufficiently low intensity at a detector you find it gives single point activation, single clicks, or it activates one only pixel. That indicates that the energy is confined to a very limited volume, and we call something that does that a particle, or in this case, a photon.
However, if you shine light on a surface, such as water, you will find some is reflected and some is refracted. That is a wave property. Further, if you send your low-intensity light through the two-slit experiment you get the interference effect characteristic of waves, even though the detector accumulates the pattern as a series of points.
The most interesting experiment is the Mach Zehnder interferometer. What happens is light goes to a beam splitter, and you get two paths. Each path is brought together by a further mirror on each path and brought to a second beam splitter, which has the ability to send the light to two detectors. What happens is that because a reflection gives a phase shift of π on reflection, the beam with the additional reflection at beam splitter 1 arrives out of phase with the other beam at beam splitter two. The net result is that through an interference effect all photons go to one detector, and let us say the total energy detected is E. Now, block one of the paths. The total energy at beam splitter 2 is, naturally E/2. That suggests strongly that all the photons that went down the unblocked path made it to the splitter, but now another phenomenon happens: both detectors fire equally. That indicates that for the photons that went down the unblocked path previously, something else went down the other path and it gave an interference effect.
In my opinion, the only rational way to explain this is to concede that there is BOTH a wave and a particle and they can travel separately if forced to with a beam splitter.
Fundamental components have aspects that are wave-like, and aspects that are particle-like. But both aspects are significantly different from what a casual use of those terms will lead you to think. They are the best words we have, but they are nonetheless misleading.
We only know where particles are when they interact. We are used to being able to track things as they move around, to watch them. But watching them is, in itself, an interaction. When we draw a diagram of a particle’s path, what we are doing is joining the dots between interactions with a line which we made up. If it is not inter
Fundamental components have aspects that are wave-like, and aspects that are particle-like. But both aspects are significantly different from what a casual use of those terms will lead you to think. They are the best words we have, but they are nonetheless misleading.
We only know where particles are when they interact. We are used to being able to track things as they move around, to watch them. But watching them is, in itself, an interaction. When we draw a diagram of a particle’s path, what we are doing is joining the dots between interactions with a line which we made up. If it is not interacting, it is not reasonable to say that a particle is somewhere, only that we can make up a line that satisfies our.
So we can separate the possible interaction into two halves: the probability that it will interact, and what it brings to the party when it does interact.
The wave part is the probability that it will interact. This spreads over a volume of space, and is wave like. In the right circumstances it can interfere with itself, creating a pattern what has holes in it, places it cannot possible interact, and other places where it is highly likely to do so.
The particle part is what happens when it does interact. Each particle has a mass, charge, spin, energy, momentum and so on. And when it interacts, it brings all of those to the interaction, which is what you would expect of a particle. In particular, for a photon, which is just energy and momentum, the thing that absorbs out has to take it all. Not taking what it wants and leaving a residue to carry on. So if an atom wants to absorb a photon, it must have a transition which can absorb the entire photon with nothing left over, but with the electron starting and finishing in a “legal” state.
So they have some properties which are wave-like, and some properties which are particle-like, but they are their own thing, not truly either.
Photons behave like waves and particles. what does this mean?
I think it’s a little more accurate to say light behaves like waves (classical) and particles (photons). (New Shimmer is a floor wax and a dessert topping. It’s online, but it appears NBC recently put it behind a sign-up wall and you have to agree not to use an ad-blocker.)
When there are obstacles for light to go through or around, we se
Photons behave like waves and particles. what does this mean?
I think it’s a little more accurate to say light behaves like waves (classical) and particles (photons). (New Shimmer is a floor wax and a dessert topping. It’s online, but it appears NBC recently put it behind a sign-up wall and you have to agree not to use an ad-blocker.)
When there are obstacles for light to go through or around, we see diffraction. In some cases we also see interference. This is light acting like it was made of waves.
But when it comes to black-body radiation, the photoelectric effect, the Compton effect, and photon statistics, it acts like a particle, the photon.
The connection between the two is given by the Einstein relation
[math]E = hf[/math]
and the de Broglie relation
[math]p = \dfrac{h}{\lambda}[/math]
Where E and p are the amount of energy and momentum carried by each photon. f is the frequency of the wave and [math]\lambda[/math] is the wavelength. h is the Planck constant, aka Planck’s constant.
In some cases you get both. You can do the two-slit experiment one photon at a time. It was done not terribly long ago by Hitachi, but using electrons, which also have wave and particle characteristics. They send it through a double-slit one electron ...
Photons are photons, they have some particle like behavior and some wavelike behavior. That is wavelike in the sense that it's described by the same maths as a wave. Same for the particle like behavior.
From what I understand of quantum physics. The probability of interaction is described by wave mathematics and the interaction by particle mathematics.
But the photon is photon. It's not just a particle. Though that's what we categories it as. But that's more convention then fact.
This particle wave duality idea and it is only an idea has arisen because we just don’t know how they interact.
Using fields, they are not real, gives approximate answers much like the geocentric model using complex geometric contraptions provided approximate answers. With the heliocentric model all those ridiculous contraptions were tossed out and a very simple model gave more accurate answers. When Kepler proved elliptical orbits everything fell into space except for mercury which took Einstein to solve.
Just because particles and waves can interfere with each other doesn’t mean that a particl
This particle wave duality idea and it is only an idea has arisen because we just don’t know how they interact.
Using fields, they are not real, gives approximate answers much like the geocentric model using complex geometric contraptions provided approximate answers. With the heliocentric model all those ridiculous contraptions were tossed out and a very simple model gave more accurate answers. When Kepler proved elliptical orbits everything fell into space except for mercury which took Einstein to solve.
Just because particles and waves can interfere with each other doesn’t mean that a particle is a field. A field is simply a mathematical construct of a wave model of matter.
I can assure you when I accelerate atoms or photons within a molecular beam they do not spread out through the universe only to give interference patterns a few feet away.
No one really knows what is the nature of photons, as that is not exactly “knowable thing”. What we can investigate is, what are the valid ways to model reality - quite a different question with much more relaxed answers than “what is the real nature of things”.
That being said, I would argue that it’s possible to use an intepretation of quantum mechanics where photons don’t exist at all, and that view pretty much removes all of quantum mystery in a pretty mundane way.
See for yourself;
I’m not quite sure why is it not more popular to view things this way. Peopl
No one really knows what is the nature of photons, as that is not exactly “knowable thing”. What we can investigate is, what are the valid ways to model reality - quite a different question with much more relaxed answers than “what is the real nature of things”.
That being said, I would argue that it’s possible to use an intepretation of quantum mechanics where photons don’t exist at all, and that view pretty much removes all of quantum mystery in a pretty mundane way.
See for yourself;
I’m not quite sure why is it not more popular to view things this way. People seem to revert back to photons after already making otherwise complete description of a quantum system, for no particular reason other than being used to doing so. Perhaps the only reason then is that too many people are completely stuck in a paradigm, overlooking much simpler alternatives (photons were, after all, a pre-cursor to the formation of Quantum theory)
It can be said, but it’s not a productive idea. Light isn’t either a wave or a particle. We know how to deal with wave mathematics and with particle mathematics. Sometime what light does is well modeled with wave mathematics and sometimes it is well modeled with particle mathematics. The mathematics that works doesn’t absolutely describe what light is.
It should not be surprising to find that analogies based on things we can see don’t always work well with things that function on much smaller scales.
The answer is neither. It is a different class of object called a quantum object or a quantum particle ( unfortunately the latter, and more common version , contains the ‘p’ word and provides a further opportunity for confusion.
Quantum object can be described by phasors, it is this that explains the apparent similarity to waves which can also be described by phasors. Quantum particles, when detected, occur in one location only, just as particles arrive in on e place, a wave arrives with its energy spread over an area (the wavefront). Thee S and P waves from the earthquake causes massive damage
The answer is neither. It is a different class of object called a quantum object or a quantum particle ( unfortunately the latter, and more common version , contains the ‘p’ word and provides a further opportunity for confusion.
Quantum object can be described by phasors, it is this that explains the apparent similarity to waves which can also be described by phasors. Quantum particles, when detected, occur in one location only, just as particles arrive in on e place, a wave arrives with its energy spread over an area (the wavefront). Thee S and P waves from the earthquake causes massive damage over a large area of Turkey and Syria. These waves did not arrive/ deposit their energy in just on place.
Forget wave particle duality- it was a problem that was identified in the early 1900’s and solve by the mid 1900s roughly speaking. It was problem - it was never a theory/an explanation.
Finally, these quantum objects are consistent in their behaviour and do NOT sometimes do this and sometimes do that. What varies is the experiment and what you are looking at. The quantum, particles do this whether you are looking or not.
Light is the end product of the combination of matter and antimatter. It is never helpful to think of light as a particle or even as a photon but rather as pure energy with an oscillating electromagnetic field. Note that the oscillating fields alternate between both types of charge - negative and positive - due to its composition of both matter and antimatter.
The oscillating electromagnetic fields trace out a sine wave as the light travels relative to an observer.
Despite light’s composition of matter and antimatter, light is neither and is categorised as a boson meaning that it has the ability
Light is the end product of the combination of matter and antimatter. It is never helpful to think of light as a particle or even as a photon but rather as pure energy with an oscillating electromagnetic field. Note that the oscillating fields alternate between both types of charge - negative and positive - due to its composition of both matter and antimatter.
The oscillating electromagnetic fields trace out a sine wave as the light travels relative to an observer.
Despite light’s composition of matter and antimatter, light is neither and is categorised as a boson meaning that it has the ability to occupy the same space as other bosons without limit. Light can spontaneously decay in to matter/antimatter pairs.
Jeez, this is a mess. Some people here have good points, though.
Light "particles" (photons) are excitations of the electromagnetic field. Similarly, all other "particles" are excitations of their respective fields (electron field, Higgs field, ...). That's all you can say without resorting to analogies.
We model "particles" by wavefunctions, which is something that is spatially distributed. Whether these are "real" or simply a mathematical abstraction is up to the philosophers. It's been interpreted as the charge density of particles, but not all particles are charged. In the case of photons, a
Jeez, this is a mess. Some people here have good points, though.
Light "particles" (photons) are excitations of the electromagnetic field. Similarly, all other "particles" are excitations of their respective fields (electron field, Higgs field, ...). That's all you can say without resorting to analogies.
We model "particles" by wavefunctions, which is something that is spatially distributed. Whether these are "real" or simply a mathematical abstraction is up to the philosophers. It's been interpreted as the charge density of particles, but not all particles are charged. In the case of photons, an oscillating electromagnetic field forms the wavefunction. Many people visualize these as wave packets:
This function is both reasonably localized (a particle-like property) and it also has an approximate wavelength (a wave-like property). So, as some people have mentioned, photons exhibit properties of both particles and waves. The wavefunction can change, e.g. compress itself to a point if the photon is detected, but photons remain mostly wavelike while travelling since they move at the speed of light and have a weak interaction with matter. A photon travelling in air will be much more spread out than the picture above suggests.
The wave-particle duality is strongly connected to Heisenberg's principle of uncertainty, since velocity is connected to wavelength. A "pure wave" will be infinitely spread out as a sine wave and will have a completely undetermined position, while a "pure particle" will be concentrated in a point and have a completely undetermined wavelength (and thus velocity). Most of the time, all particles are something in between. Call them what you want. I usually refer to them as fields, although this might not be the way particle physicists use the word.
It is both.
According to quantum mechanics, every particle acts, in some ways, like a wave. Wavelength is inversely proportional to energy, so the wavelength of a heavy particle is very small. Any macroscopic object has a wavelength infinitesimally smaller than its size, so you don't observe it acting like a wave. On the other hand, since photons (especially radio-band photons) don't have much energy, their wavelength is large enough that their wavelike properties matter a lot.
They are neither particles nor waves. Those are descriptions from QM, which has been superseded by QFT. The description of physical reality in QFT describes fields and the quantum excitations of those fields. Fields are physical expressions of opposing fundamental forces in dynamic equilibrium; the dynamism of that oppositional condition causes the field to oscillate and the peaks of those oscillations are the quantum excitations of that field. They can appear to behave in ways that remind us of particles in that these peaks of oscillating fields are incremental units of energy, yet they can a
They are neither particles nor waves. Those are descriptions from QM, which has been superseded by QFT. The description of physical reality in QFT describes fields and the quantum excitations of those fields. Fields are physical expressions of opposing fundamental forces in dynamic equilibrium; the dynamism of that oppositional condition causes the field to oscillate and the peaks of those oscillations are the quantum excitations of that field. They can appear to behave in ways that remind us of particles in that these peaks of oscillating fields are incremental units of energy, yet they can also appear to behave in ways that remind of us waves, but these are just descriptions of apparent behavior; they are not absolute categories at all.
They are neither little ball-like particles nor are they classical waves. They are “particles” in a quantum sense whose behavior can sometimes be modeled as ball-like particles and sometimes as classical waves. They can also be modeled as excitations of fields according to quantum field theory.
One of the hardest things about understanding quantum physics is moving beyond understanding things in terms of analogies to observable, classical phenomena.
Here's a new thing.
By the 1950's it was generally agreed that "the photon's wave and quanta (particle) qualities are two observable aspects of a single phenomenon, and cannot be described by any mechanical model." (Joos, George. Theoretical Physics. London and Glasgow: Blackie and Son Ltd. (1951).
In other words, it is somehow both a wave and a particle, but the most recent research in optics has shown that it can, in fact be "be described by [a quite simple] mechanical model" -- a particle that travels along a tight spiral path.
Bear with me a minute.
The story began when Richard A. Beth (1936)
Here's a new thing.
By the 1950's it was generally agreed that "the photon's wave and quanta (particle) qualities are two observable aspects of a single phenomenon, and cannot be described by any mechanical model." (Joos, George. Theoretical Physics. London and Glasgow: Blackie and Son Ltd. (1951).
In other words, it is somehow both a wave and a particle, but the most recent research in optics has shown that it can, in fact be "be described by [a quite simple] mechanical model" -- a particle that travels along a tight spiral path.
Bear with me a minute.
The story began when Richard A. Beth (1936) showed that photons exhibit angular momentum. The only things that can have angular (i.e. orbital) momentum are things that rotate around an axis. If such a particle is also moving along at right angles to the plane of rotation, then its path will be helical.
Photons then, it could be argued, behave like particles that travel along a spiral trajectory, and one complete revolution has been shown to take the same amount of time as one oscillation at that wavelength, which neatly resolves the wave/particle duality conundrum. A spiral, seen from the side, is a wave.
Now an important thing about angular momentum is that it must, by Law, be conserved. By convention, linearly polarised light is usually illustrated diagrammatically as a wavy line, as though the photons were following a zigzag path between imaginary 'poles', but that would breach the law of conservation of angular momentum. How can we resolve this problem?
Wikipedia states that " circular and linear polarization, can be considered to be special cases of elliptical polarization."
Since we are talking about angular momentum and spirals, it might be more reasonable to say that elliptical and linear polarisation are special cases of circular polarisation.
A strange, oxymoronic term anyway, 'circular polarisation', since no poles are involved.
We know, however, that circularly polarised light may be a left-handed or a right -handed spiral -- rotating clockwise or anticlockwise. In fact one of the 3D television systems -- RealD TV -- utilises this phenomenon by providing viewers with a pair of spectacles with one lens that is opaque to everything except left-handed circularly polarised light while the other is opaque to everything except light with right-handed polarity.
When a pristine (circularly polarised) photon glances off a solid surface the photon's wavelength and angular momentum will be conserved, so its spiral path, as well as changing direction, must become distorted in a very specific manner. (Fig.1)
FIG. 1
After a collision the circular path of the photon around its axis of rotation appears, from the observer's perspective to be elliptical. (Fig.2)This is referred to as elliptically polarised light.
Fig. 2
It has also been known for many years that when photons glance off a very flat, non-metallic surface such as a sheet of water or glass, a proportion of the light becomes linearly polarised, and if the light strikes the surface at a certain angle (50 - 60 degrees) then most of the light will be polarised parallel to the surface. For this reason some fishermen wear vertically polarised sunglasses to cut out that glare.
Fig. 3 is a more realistic representation of horizontally polarised light than the traditional zig-zag. It is just an extreme form of elliptically polarised light and the angular momentum, velocity, wavelength and amplitude all remain unchanged.
FIG. 3
Another fact that has been known for a long time is that horizontally and vertically polarised light can easily be rectified back to its pristine spiral form simply by passing it through a quarter-wave plate that photographers commonly use to improve contrast. Alternatively you can pass it through a simple rectilinear prism called a Fresnel rhomb or a sheet of mica, while a half-wave plate will reverse the 'polarity' from clockwise to anticlockwise and vice versa.
In space of course, there are very few solid objects for light to collide with, so it will tend to retain its natural circular form. On the surface of our planet much of the light will have collided with something or other before we see it but nevertheless it is possible to see perfectly well through RealD 3D glasses so we know that there is still plenty of pristine, 'circularly polarised' light all around us.
There's more to it of course. The photon generates an electric field as it travels along as well as a magnetic field at right angles to it. That's why light is called electro-magnetic radiation. In addition it has been shown that photons not only exhibit angular momentum, they also have spin momentum.
A team of physicists at Glasgow university has been studying circularly polarised light for some years and their work illustrates very clearly the spiral forms described by the electric and magnetic fields, as well as providing a significant clue to the elusive amplitude of light.
You may have noticed that scientists very rarely mention the amplitude of light waves -- i.e. the vertical distance from peak to trough. For most waves it is proportional to the energy in the wave -- the higher the wave the more power it has -- but, with light, the energy increases with frequency (wavelength) and there seems no way to know if amplitude means anything at all in the conventional model of light.
Serge Haroche recently measured the amplitude of a single photon "in a box" and received the Nobel Prize for it, though in his prize-winning paper he omits to mention just what the amplitude of that photon was. It's a very nice, shiny box though.
Miles Padgett’s Glasgow team simply focused a ray of circularly polarised light into such a tight beam that it was nothing more than a stream of single photons and observed the results projected on a screen http://homepage.cem.itesm.mx/fdelgado/ciencia/cadi/ref11.pdf (Fig.2) Every photon that struck the screen landed somewhere on a circle, just as you would expect if the photons were spaced randomly along a spiral. However tightly they focused the beam, not one photon struck the middle of the circle, nor outside the circle.
They really should have won that Nobel Prize but, because of the way they were approaching the subject, they chose to call the phenomenon the "annular intensity profile".
This is a more accurate description than 'amplitude' anyway, because only waves have amplitude, and light, as we have seen, is not a wave in that sense. Nevertheless the diameter of the spiral corresponds exactly to amplitude in the same way that the distance travelled along the axis of the spiral in one complete revolution corresponds exactly to wavelength.
Now it seems that nature strongly objects to anything travelling faster than 186,000 miles a second -- the speed of light -- yet, if the helical model stands up to scrutiny, the photon, in moving 186,000 miles 'as the crow flies' will have followed a spiral path a good deal longer than this during that one second.
However much energy a photon possesses, and that seems to be without limit (the current record is 10 to the power 20 electron volts -- about equal to the energy of a well struck cricket ball -- per single photon), nature won't let it exceed the speed limit. Instead it makes the wavelength shorter and shorter, so that the photon rotates around its axis more and more times for every centimetre that it travels forwards.
It's just like the speed limits set by traffic authorities. If the sign says 30mph, it doesn't matter how fast your engine is revving, how much fuel you are burning or how fast the pistons are travelling inside the engine. The law only considers forward motion.
The spiraling photon isn't breaking any fundamental law of physics, it's just that the law needs to be slightly reworded so as to specify linear motion.
The helical model also neatly explains diffraction. When light strikes a prism, the different colours of light take slightly different paths, the shorter, blue wavelengths being bent more than the red. If you consider the spiral path the photons take, it is clear that a longer wavelength will strike the glass at closer to 90 degrees and the tighter spiral path of blue photons will hit the surface at a more acute angle.
Both will also strike a pyramidal prism on the downward leg of its spiral, regardless of whether it's left or right handed, so both will be diffracted downwards.
This also explains why the light that becomes linearly polarised on water strikes it at such an obtuse angle. It is the angle at which the face of the spiral lies almost flat on the water.
As if that isn’t enough, the helical photon model would also predict that only circularly polarised light travels at 186.000 miles a second (the “speed of light in a vacuum” — c.) If we consider the spiral path of the deflected photon in fig 1, above, we can see that for half of each rotation the photon is travelling slightly backwards relative to its linear trajectory, so it would cover less distance in a second than circularly polarised light and this testable hypothesis has indeed been verified — [1411.3987] Photons that travel in free space slower than the speed of light . The difference amounts to some 3mm per kilometer in the original experiment, which showed that only plane (i.e. circularly polarised) waves travel at c. The implications of this fact are immense for both physics and cosmology.
The entire big bang theory is based on the assumption that all light travels at c and that the observed red shift in distant galaxies is due to actual expansion of the universe. In fact, since light rays are deflected by gravity, every time a photon enters or leaves a gravitational field its transverse structure will be altered and its speed will be correspondingly reduced, causing the observed light to be red shifted.
The further it has traveled the redder it will appear and at the greatest distances the emissions will be at infra red, radio or microwave frequencies. This leaves us in a very much larger universe than is currently believed, which is not expanding, was not smaller in the past and which did not therefore originate in a big bang.
I wouldn't advise students to mention any of this in an exam. If you want to pass your exams, just draw the zig-zags, but it is a great time to think about going into optics for your PhD.
Let me briefly try to understand how.
Quantum field theory (QFT) is the best tested fundamental theory of physics (yet). It seems to be saying that there exists a certain fundamental efficacy throughout the universe, called the quantum electromagnetic (EM) field (as an analogy, say, like a universe size drum!), having infinitely many discrete states of possibility or modes of excitation (say, like
Let me briefly try to understand how.
Quantum field theory (QFT) is the best tested fundamental theory of physics (yet). It seems to be saying that there exists a certain fundamental efficacy throughout the universe, called the quantum electromagnetic (EM) field (as an analogy, say, like a universe size drum!), having infinitely many discrete states of possibility or modes of excitation (say, like the modes of the drum’s vibration).
A photon is, by definition, an elementary excitation mode of possibility of the EM field, that is c o m p l e t e l y characterized by the quintet, say, of their energy, momentum, spin, amplitude and phase — a l l the five at the s a m e time. The first three are particle-like and the last two are wave-like. So, a photon exists as a w h o l e unit of its energy, mome...
Small particles behave differently than what you would expect. You can think of particles which construct matter as particles who act like waves. Quantum mechanics is a very big subject, but the bottom line is this: These "particles" can "fool" the world by having a presence at two places at once. It's kind of like looking through a glass which blurs up everything. When you're far away, it looks almost the same, but close enough everything blurs up.
Because these particles fool the world by being at one place and not the other, they end up fooling themselves and interfering with themselves. Be
Small particles behave differently than what you would expect. You can think of particles which construct matter as particles who act like waves. Quantum mechanics is a very big subject, but the bottom line is this: These "particles" can "fool" the world by having a presence at two places at once. It's kind of like looking through a glass which blurs up everything. When you're far away, it looks almost the same, but close enough everything blurs up.
Because these particles fool the world by being at one place and not the other, they end up fooling themselves and interfering with themselves. Because of their small size and high speed, they see the world differently. The faster a particle goes, the more chance it has to interfere with itself by being near itself in another place in time, or pass in a different hole then they were targeted at. This causes the particles to act as waves and bump with themselves when speeding really fast. It's kind of like a "calculation error" effect of the real world.
More reference here:
http://en.wikipedia.org/wiki/Wave%E2%80%93particle_duality
And the double slit experiment:
http://www.youtube.com/watch?v=uSnVnyQA8UU
Look at this image on electron diffraction:
Do you see the dots? That is electrons exhibiting particle nature. Do you see the bright and dark bands? That is electrons exhibiting wave nature.
Wave nature pretty much controls where the electrons go. Particle nature pretty much controls what the electrons do when they arrive.
Look at this image on electron diffraction:
Do you see the dots? That is electrons exhibiting particle nature. Do you see the bright and dark bands? That is electrons exhibiting wave nature.
Wave nature pretty much controls where the electrons go. Particle nature pretty much controls what the electrons do when they arrive.
Q: Is a photon a particle or an event?
No. A photon is a quantum, which is a fancy name meaning “doohickey that sometimes acts like a particle and sometimes acts like a wave depending on how you look at it.”
A photon is not a particle. It is never, under any circumstances a particle.
A photon is not a wave. It is never, under any circumstances, a wave.
A photon is a quantum, and sometimes it acts like a wave and sometimes it acts like a particle. But if you allow yourself to think it is one or the other or both, it will seem weird and magical. But it isn’t. It’s just a photon. It only seems weird
Q: Is a photon a particle or an event?
No. A photon is a quantum, which is a fancy name meaning “doohickey that sometimes acts like a particle and sometimes acts like a wave depending on how you look at it.”
A photon is not a particle. It is never, under any circumstances a particle.
A photon is not a wave. It is never, under any circumstances, a wave.
A photon is a quantum, and sometimes it acts like a wave and sometimes it acts like a particle. But if you allow yourself to think it is one or the other or both, it will seem weird and magical. But it isn’t. It’s just a photon. It only seems weird and magical because we don’t understand it very deeply.
A photon is a type of elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force (even when static via virtual particles). The photon has zero rest mass and always moves at the speed of light within a vacuum.Like all elementary particles, photons are currently best explained by quantum mechanics and exhibit wave–particle duality, exhibiting properties of both waves and particles. For example, a single photon may be refracted by a lens and exhibit wave interference with itself, and it can b
A photon is a type of elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force (even when static via virtual particles). The photon has zero rest mass and always moves at the speed of light within a vacuum.Like all elementary particles, photons are currently best explained by quantum mechanics and exhibit wave–particle duality, exhibiting properties of both waves and particles. For example, a single photon may be refracted by a lens and exhibit wave interference with itself, and it can behave as a particle with definite and finite measurable position or momentum, though not both at the same time. The photon's wave and quanta qualities are two observable aspects of a single phenomenon, and cannot be described by any mechanical model; a representation of this dual property of light, which assumes certain points on the wavefront to be the seat of the energy, is not possible. The quanta in a light wave cannot be spatially localized.
Source- Wikipedia.
Early in the last century,people discovered that light which was a wave had particle like properties. Around the same time they discovered that particles - electrons could display wave like particles. They introduced the term wave particle duality - it was reasonable at the time. 100 years later it is just incorrect to use these ideas.
These time things are quantum objects and behave in a way which is perfectly consistent. They are not waves or particles or both and are always - quantum objects - they don’t sometimes do one thing and other times do some thing different.
The modern view, which do
Early in the last century,people discovered that light which was a wave had particle like properties. Around the same time they discovered that particles - electrons could display wave like particles. They introduced the term wave particle duality - it was reasonable at the time. 100 years later it is just incorrect to use these ideas.
These time things are quantum objects and behave in a way which is perfectly consistent. They are not waves or particles or both and are always - quantum objects - they don’t sometimes do one thing and other times do some thing different.
The modern view, which does not get represented in school text books and which largely is not taught up to the age of 18, is that there are three types of object. Classical waves, classical particles and quantum objects.
If anyone talks about wave particle duality they are about 100 years behind the times.
Notable exception- if it is your teacher telling you what your examination syllabus specifies, it would be wise to answer in terms of wave particle duality. Once you have passed the exam- you can move on and be with the times.
No it is not.
It can display properties that we associate with waves or particles, but ultimately it is neither. The need to distinguish between the two is based on our human perception, not any fundamental quality of existence.
A photon is a quantum system. In that sense it is neither a wave nor is it a particle. It has aspects of both, but it is something quite different. If we look for a wave, we find one. If we look for a particle,we find one. Deep down in the machinery of the universe, there is a principle that tells us we can't see both of these aspects at the same time.
Your question is framed in the language of quantum mechanics, an early version of quantum physics which has been superseded by QFT. QFT emphasizes the primacy of the field, not the wave / particle duality. QFT describes what we used to misleadingly call “particles” as quantum excitations of the field. A field is a region where fundamental forces interact; force interactions are always dynamic, never static, a condition which makes fields oscillate. Field oscillations are the mechanisms by which fields interact with each other to generate all phenomena. An excitation of the field describes thos
Your question is framed in the language of quantum mechanics, an early version of quantum physics which has been superseded by QFT. QFT emphasizes the primacy of the field, not the wave / particle duality. QFT describes what we used to misleadingly call “particles” as quantum excitations of the field. A field is a region where fundamental forces interact; force interactions are always dynamic, never static, a condition which makes fields oscillate. Field oscillations are the mechanisms by which fields interact with each other to generate all phenomena. An excitation of the field describes those interactions. The word “quantum” literally means minimum quantity; a quantum is a measurement, not an object that does things. Atomic and subatomic scale energetic transactions are observed / detected / measured by classical machinery which show researchers various ways those quantum scale energetic transactions occur; one way of viewing / interpreting the quantitative results calls to mind discrete ‘particles’, another way of viewing the same process calls to mind the non-discrete, contiguous wave form. These are inaccurate descriptions of physical reality. QFT does not perpetuate this misconception of small scale physical reality; the fields themselves are contiguous but thanks to their oscillations, their interactions are intermittent, incremental, hence the concept of the quantum, the minimum quantity of energy content that can be measured in any given field.