Quantum physics says that energy is quantised, and since the energy of a photon is only dependent on the wavelength, the wavelength of a photon is quantised. This means that even though an infinite amount of numbers exist between 380 and 700, there is a finite amount of wavelength a photon can have between 380nm and 700nm.  1) How can I mathematical predict if it is possible for a photon to have a given frequency?  2) How many possible frequencies can a photon have within the ?   3) In general, in there an equation for how many possible frequencies a photon can have within any given range?  Edit: I managed to find an answer on . "[T]he frequency available [for a photon of light] is continuous and has no upper or lower bound, so there is no finite lower limit or upper limit on the possible energy of a photon." I think that what it is meant when physicists say 'energy is quantized' is that particles of matter have quantized energy levels, but the energy levels of particles carrying energy between that matter (e.g. photons) are not quantized.
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I'm just starting to learn physics and I have a question (that is probably stupid.)  I learned that energy levels that the bound electron can have are discrete. I also learned that when an electron transitions from one level to another, a photon with a specific wavelength (energy) is created and released into the wild.  My question is this: are there holes in the electromagnetic spectrum, values of frequency that the created photon can't possibly have?
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So my physics examinations are coming up and I was going through my notes on waves, but I realized that there were some discrepancies.   In my notes, the energy of a wave is directly proportional to the square of the amplitude, ie. $E \propto A^2$  However, I recalled that, in one of my physics lessons, our physics teacher told us that the energy of a wave can be calculated using $E=hf$, where $h$ is the Planck constant and $f$ the frequency.  Hence I was rather confused and tried searching google for answers but couldn't find any suitable ones. To the best extent of that research, what I found out was (apparently) (for visible light), the frequency of the wave could be used to calculate the energy of the wave, while the amplitude was used to determine the intensity of the wave.  So I was wondering, firstly, whether the above statement was correct, and secondly, in the event it is correct, whether it would be applicable to all kinds of waves, (ie. Sound waves, water waves, other EM waves, etc.), and thirdly, back to the original question, how do we calculate the energy of a wave?  Thanks. :)
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Because an object's temperature is inversely proportional to the wavelength of blackbody radiation which it emits, physicists have theorized the existence of  at around $1.4×10^{32}$ K.   Does this imply that temperature must be discrete? Meaning, the temperature could never be $1.0×10^{32}$ K, because that would imply a wavelength which is a non-integral multiple of the Planck length.  If it does imply this, does that mean that a system, if approaching the Planck temperature, and given more energy, would suddenly and radically change states from $0.7×10^{32}$ K to $1.4×10^{32}$ K? (perhaps much like a )  Pardon me if this question is bizarre, as I am not a physicist by profession (except maybe of the armchair variety).
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Is there any size of photon if so what is it?  And also which particle had smallest size / radius / volume considering all of the matter.
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I am starting to learn about quantum mechanics and was wondering about the solutions to a question about a particle in an infinite potential well of length $L$.  The solutions are: $$\psi_n(x) = \sqrt{\frac{2}{L}}\sin\left(\frac{\pi n x}{L} \right)$$  And I was wondering what is the meaning of $n$. Isn't there supposed to be only one wave function? In that case, $\Psi = \sum_{n=1} ^\infty a_n \psi_n$, but what are the $a_n$? Or maybe it is probabilistic, and we don't know which $\psi_n$ the particle is currently in?
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If you have a set amount of space, lets say 10 cubic centimeters, and you would be able to trap photons in there. If you would then add more and more photons to that space, could you then go on infinitely or would you eventually run into a maximum amount of photons that can be in that space?
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If you emit a single photon, wait an interval, emit a second photon, wait the same interval, and keep repeating, is the resultant stream of photons describable by the frequency at which you emitted each one? Or does each photon have its own "frequency", independent of the rate of emission? I thought the former description explained the Doppler effect.
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The electromagnet spectrum looks to be continuous, yet energy is discrete. Shouldn't one see evidence of the electron's "quantum leap"? What's going on?     Moderator, please size my photo. Thank you.
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I'm having a discussion with someone. I said that it is -even theoretically- impossible to reach $0$ K, because that would imply that all molecules in the substance would stand perfectly still.  He said that this isn't true, because my theory violates energy-time uncertainty principle. He also told me to look up the Schrödinger equation and solve it for an oscillator approximating a molecule. See that it's lowest energy state is still non-zero.  Is he right in saying this and if so, can you explain me a bit better what he is talking about.
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We've all heard of the inverse square law, but apparently that refers to the flux or intensity or number of photons hitting an imaginary surface area. This is not exactly what I want to ask about.  I'm asking about the energy level of an individual photon, or individual ray of light. The light could be any frequency or wavelength.  If I'm not mistaken, the amplitude of the light ray is directly related to its energy.  Consider a ray of light travelling through a vacuum. Does its energy decrease over time according to inverse square law? Maybe inverse linear? Or not at all?  This question comes from . If it's true that the energy doesn't diminish at all, then that would mean a laser beam shot into space (and never hits anything) would never lose any energy and arrive at the other side of the Universe with the same energy it started with. That's kinda hard to believe.  EDIT: It appears "energy" and "amplitude" are not synonyms for light rays. Apparently the concept of waves is tricky for light, since after all, a vacuum has no medium to propagate through in the normal wave sense. So let the question be, "Does an individual photon lose energy solely from the act of traveling through a vacuum?"
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I recently read an old physics news about the Higgs boson where it was observed to decay into 2 photons and I was wondering why it wouldn't have decayed into a single photon with the combined energy of 2 photons?
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says that a photon of  to $10^{-62}$ kg has been detected:     10×10−62 kg   Mass equivalent of the energy of the lightest photon   detected [citation needed]   This equates ($mc^2=E=hf=h\frac{c}{\lambda}$) to a wavelength of $\lambda=2.2\times 10^{20}$ m (roughly a million ly)! Can anyone provide a citation for this measurement? And how can such a large wavelength/low energy photon be detected?  Edit  Apart from the quotation (true/false un/reliable un/documented ....), I'd like to learn about the lightest photon detected, or about the instrumental limit: what is the lower limit of energy that can be registerd by an intrument (or the greatest wavelength), and how it is done? For example, can you detect a radiowave of 1 Hz?
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My textbook and the following extract from feynman's lectures present the same idea regarding wavetrains and uncertainty in their wavelengths. Why is it that a wavetrain confined to some space has an uncertainty in its wavelength or the wave number? Is not a confined wave-train equivalent to a burst of successive pulses which can have a definite wavelength according to their origin or nature of origin.   Next, i understand that the De Broglie relation relates the uncertainty in wavelength to the uncertainty in momentum but what links the finiteness of the wave-train to the uncertainty in position?
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When light is emitted (or received) one photon at a time, what is the duration of each pulse? Is it related to the wavelength? Is it possible to create a laser pulse (or a radio wave) shorter than the wavelength (period of oscillations)?
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in classical physics frequency represents how many cycles in one unit time, but I do not know how we define a frequency for a particle? what does it mean for a particle to have a frequency, the book I read it from just says Energy is proportional to the frequency of the photon but where is frequency?
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I'm reading a book by George Gamow, "Thirty years that shook Physics" and have trouble understanding his way of describing the UV catastrophe. In a first part he points out that applying the Equipartition Theorem (or principle) to radiation would lead to a situation in which every wave of each frequency should have $0$ energy (or, better, $E/\infty$, if $E$ is the original amount of energy of the system). Next he states that if we introduce for instance red light in a Jeans cube and we apply the principle to this situation, we could have the absurd consequence that the cube could be a source of high fequency radiation ($\gamma$, $X$, etc).  Now, how can the second situation even exist if (equvalently absurd) each frequency had zero energy to begin with? I cannot see a "UV" catastrophe, rather a "disappearing energy" catastrophe. What am I missing?
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According to Quantum Mechanics, in order for an atom to absorb a photon the energy of the photon must be precisely that of a "jump" between energy states of the atom.  How precise must it be?   If I create a photon with an energy within an error of 0.0001% of that of an energy state, will it be absorbed by my atom?