# What is De broglie: Definition and 272 Discussions

Louis Victor Pierre Raymond, 7th Duc de Broglie (, also US: , French: [də bʁɔj] or [də bʁœj] (listen); 15 August 1892 – 19 March 1987) was a French physicist and aristocrat who made groundbreaking contributions to quantum theory. In his 1924 PhD thesis, he postulated the wave nature of electrons and suggested that all matter has wave properties. This concept is known as the de Broglie hypothesis, an example of wave–particle duality, and forms a central part of the theory of quantum mechanics.
De Broglie won the Nobel Prize for Physics in 1929, after the wave-like behaviour of matter was first experimentally demonstrated in 1927.
The 1925 pilot-wave model, and the wave-like behaviour of particles discovered by de Broglie was used by Erwin Schrödinger in his formulation of wave mechanics. The pilot-wave model and interpretation was then abandoned, in favor of the quantum formalism, until 1952 when it was rediscovered and enhanced by David Bohm.Louis de Broglie was the sixteenth member elected to occupy seat 1 of the Académie française in 1944, and served as Perpetual Secretary of the French Academy of Sciences. De Broglie became the first high-level scientist to call for establishment of a multi-national laboratory, a proposal that led to the establishment of the European Organization for Nuclear Research (CERN).

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1. ### I De Broglie Wavelength at rest: λ = h/p = h/0 when v=0?

De Broglie Wavelength is λ = h / p. So at rest, v=0, and p=mv, so p=0. This means that λ = h/p = h/0 so we run into a divide by 0 issue, or infinite wavelengths for objects at rest. Is this line of reasoning flawed? Or can we consider v=1 for rest masses? Time Dilation is related to v. The...
2. ### B Time Dilation & Muon De Broglie Wavelength: Explained

I understand it's experimentally verified muons traveling at relativistic speeds relative to an observer will be observed to have longer half-life than would be observed in the rest frame of the muons, which is explained theoretically by a relativistic time dilation effect. Does this correspond...
3. ### I E=hf for massive particles, but which Energy exactly?

Hi there, I'm a bit confused about the E=hf equation for mass particle(f for frequency), and Lorentz Invariant (E^2 -p^2c^2=m^2c^4). The question is, which energy is it? Total Energy- Kinetic plus Rest, or only kinetic energy. Now, if it's total energy, then you get that a particle at rest...
4. ### I Confused on the premise behind De Broglie's hypothesis

I'm confused on how De Broglie's hypothesis works. I've attached my thinking in a pdf file below. I'm not an expert in the field of particle physics(I'm only in high school), so there may be some error in my logic(I really think so, or else De Broglie was wrong!(hint:he isn't)) I've also read...
5. ### Can a Single Point Grapefruit Create an Interference Pattern?

I tried using lamba = h/p as follows: (6.626 * 10^-34 J *s) / (8 m.s * 0.6 kg) = 1.38041667*10^−34 and then using the small angle approximation sin(alpha) = lamba/d as follows: (1.38041667*10^−34)/(0.6m) = 2.30069444 * 10^−34 then converting to radians with the following: (2.30069444 *...
6. ### A De Broglie to Schrödinger to Thomson to Bohm?

I'm investigating some newly conceived Hamiltonians using the approaches of de Broglie and Schrödinger as jumping off points. Lanczos in "The Variational Principles of Mechanics" p. 278 describes and analyzes them. Neither de Broglie nor Schrödinger really completed the program of the H-J...
7. ### De Broglie Relations Confusion

I've been attempting to run through some quantum mechanics and I've seen something extremely odd, and I just can't spot my mistake. I know the relationships: ##p = \frac{h}{\lambda}## and ##E = hf##. I also know the relationship ##E = \frac{p^2}{2m}##. I tried to show using the energy-momentum...
8. ### A question related to de Broglie wavelength and the Uncertainty Principle

"Now, if an electron has a definite momentum p, (i.e.del p = 0), by the de Broglie relation, it has a definite wavelength.A wave of definite (single) wavelength extends all over space. By Born’s probability interpretation this means that the electron is not localised in any finite region of...
9. E

### When does the wavefunction wavelength equal the De Broglie wavelength?

For instance, in the case of the infinite square well, the wavelength of the wavefunction is \frac{2L}{n}. This also turns out to be the De Broglie wavelength, and and we can find the possible energies directly from the Schrodinger equation, or by using the De Broglie relations. However, if the...
10. ### I Did de Broglie contribute later to pilot wave theory?

If I recall correctly it was in Adam Becker's book "What is Real?" where I read that late in life de Broglie took up again the pilot wave theory that he had introduced at Solvay in 1927 and that Bohm had done so much work on in the interim. Did de Broglie make any contributions to pilot wave...
11. ### How to derive the de Broglie Relation

I began by taking E = mc^2 and E = hf , where h is Planck's constant, and then rewrote E as 1/2mv^2. I rewrote f as c / λ, which made hf become h*c / λ. I then set this expression equal to the Kinetic Energy equation 1/2mv^2, which gave me: 1/2mv^2 = h*c / λ I then replaced c on the...
12. ### How can I derive the relativistic de Broglie equation?

I know I can get momentum in terms of kinetic energy in this way: K = .5mv^2 => p = sqrt(2mK) substitute into debroigles gives me: λ = h/(sqrt(2mk)) = hc/(sqrt(2mc^2K)) which would be the nonreletivistic equation but I need the reletivistic equation. I can plug in the equation for...
13. ### I De Broglie Waves: Hypothesis, Derivation & References

I need to know how did debroglie come to this hypothesis, derivation. And his original paper on matter waves. And some highly good reference on this topic.
14. ### De Broglie wavelength of an electron

I'm reposting this thread with some editing suggested by fresh_42: 1. Homework Statement Calculate the mass, velocity and the de Broglie wavelength of an electron and an alpha particle, given the kinetic energy K = 2MeV Homework EquationsThe Attempt at a Solution please find attached![/B]...
15. ### I The definition of velocity in the de Broglie relation

I apologize ahead of time for the simplicity of the question, but this has really been bothering me.Given the de Broglie relation, assuming natural units, where ##\hbar = 1##: $$\begin{split} \vec{k} &= M \vec{v} \end{split}$$My question regards velocity and...
16. ### A Is energy contained in matter wave equals hv like EM waves?

h is plank constant and v is frequency. I was using this to derive the TDSE. But I ran into problem because to substitute k^2 in E=h^2/8mpi^2 * k^2, I can use single derivative of psi squared or double derivative, both of which tend to give the correct answer. So, is my assumption of energy...
17. ### I De Broglie relation - new student

Hi physics folk, Thought you guys would be able to clarify something, self study learner here getting into quantum. So I've just learned about the De Broglie relation and The Photoelectric effect and am bamboozled (in a good way). The notion being that light is absorbed in packets. However I'm...
18. ### I Compton's Effective Velocity and de Broglie == numerology?

In Compton's 1923 paper, he notes that the scattered wavelength's angular dependence is identical to the Doppler Shift due to an electron moving with the incident wave at an effective velocity: $$\beta = \frac{ h \nu_0 } { h \nu_0 + m_0 c^2 }$$ What's really interesting is that if you calculate...
19. ### I De Broglie relation using four momentum in particle physics

In particle phyisics four-momentum is used and De Broglie relation is used to understand what lenghts can be "seen" in an experiment. Here (page 6) https://people.phys.ethz.ch/~pheno/PPP/PPP2.pdf it is claimed Where ##Q^2## is not actually "momentum" but its the square of the four momentum...
20. ### De Broglie wavelength of electron and proton

Homework Statement Homework EquationsThe Attempt at a Solution de Broglie wavelength λ of a particle = h /P a) since mass of proton is more than electron and speed is same , momentum of proton is more . De Broglie wavelength of proton will be less . b) wavelengths will be same . c) Using...
21. ### I Does the de Broglie-Bohm pilot wave theory make predictions?

I find the de Broglie-Bohm pilot wave theory interesting but what I still feel missing in the descriptions I could find so far is that it reformulates what we already know but nobody speaks of new testable predictions that could eventually distinguish it from other interpretations (such as a new...
22. ### Wavefunctions and the de Broglie wavelength

The position wavefunction makes a spatial probability amplitude wave right? And it is the combination of different frequencies My question is that if these frequencies are the spatial frequencies in the debrogile relations
23. ### I The relativistic de Broglie equation

I'm having trouble understanding how the 4-wave vector is derived, and also how it is then used alongside the 4-momentum vector to formulate the relativistic de Broglie equation. The inner product of the 4-momentum vector with itself, is an invariant quantity. If we define the 4-momentum...
24. ### I A question about a particle's de Broglie wavelength

For electron scattering experiment which measures charge radius of the nucleus, it's said that energies of scattering electrons (or protons) must be such that their wavelength size is of the same order as nuclear dimensions. While i understand why this must be true I'm not entirely sure. My...
25. ### "Seeing" particles with De Broglie visible wavelengths

Say an electron is fired with the same De Broglie wavelength as blue light. If the electron were to reach your eye, would you see blue, or would something else happen?
26. ### E = hf what sort of Energy is this?

Homework Statement Is this E - say of an electron - the very E in E2 = (mc2)2 + (pc)2? If it isn't, what sort of Energy is this? Help is greatly appreciated! Homework EquationsThe Attempt at a Solution
27. ### I Interpreting "momentum" in WKB approximation

According to WKB approximation, the wave function \psi (x) \propto \frac{1}{\sqrt{p(x)}} This implies that the probability of finding a particle in between x and x+dx is inversely proportional to the momentum of the particle in the given potential. According to the book, R. Shankar, this is...
28. ### A Why is the Matter wave analogous to photon and derived from it?

The electromagnetic wave derivation uses the fact that charge enclosed is zero and it goes to obey plane wave equations. Lets say we were deriving a wave equation from maxwell's equations for electron wave motion, but we assume that charge enclosed is not zero, and come up with some...
29. ### I De Broglie Momentum doesn't seem in Agreement with p=mv

Hi there. So I had this lab last week about De Broglie hypothesis. In a simulation, we plugged in the electron velocity and the computer gave back a beautiful wavefunction, from which I can measure the wavelength. So here I have an electron going at 0.6 m/s with a wavelenght of 0.00060606...
30. ### I De Broglie wavelength in non-constant potential?

Hi. Does the de Broglie wavelength have any significance for the wavefunctions of particles in a potential that is non-constant in no region of space? As far as I can see, the solutions of the time-independent Schrödinger equation are only sinusoidal if ##E>V=const##. This is enough to derive...
31. ### B De Broglie - Where's the rest?

Given De Broglie's equations of a quantised wave: E = 2.Pi.hbar.c Where: E = Energy Pi = PI (Ratio of circumference to radius) hbar = Planck's constant (Reduced over 2.Pi) c = celerity, causal displacement per time interval In most texts this is summarised as: E = h.nu Where: h = Planck's...
32. ### I Question about the deBroglie hypothesis

Hi, I am a new member here : ) I have always wondered about this. It seems that the answer is easy but I missed an important lecture. De Broglie proposed that just as light has both wave-like and particle-like properties, electrons also have wave-like properties. Why is that? I know the relation...
33. ### B De Broglie Wavelength & Classical EM Wavelength Comparison

Under what condition would particle de Broglie wavelength be equal to the classical EM wavelength?
34. ### De Broglie wavelength and energy levels

Homework Statement In the earliest circular planetary model of the atom the electron and proton orbited a common centre. The electrostatic forces alone provided the force field. However an accelerating charged body will send out electromagnetic waves and the orbiting charges would consequently...
35. ### I Energy associated with matter waves of macroscopic objects

Consider an object of mass 1kg moving with a speed of 1m/s. Theoretically , the de broglie wavelength associated with it is about 3.6x10-37. Now if we calculate the energy associated with this wave it comes out to be 3x1011. This is a huge amount of energy which could be very hazardous but it is...
36. ### Is de Broglie's Pilot Wave Theory Accurate?

In 1924, when de Broglie proposed the pilot wave, he seems to be saying that the velocity of the individual oscillations of the pilot waves, v', is always greater than the velocity of light c, and its relationship to the velocity of the particle v, is given by v' = c^2 / v Is this formula...
37. ### A The de Broglie wavelength: What happens in the case of a frame change?

I have a problem to understand the de Broglie wavelength. We know that also particles undergo scattering and interference at a double slit. The interference pattern is calculated by the use of the de Broglie wavelength which is defined as lambda = h / p ; p is the momentum of the particle. This...
38. ### I De Broglie: Kinetic or Total Energy?

Just a quick question (although there is a followup depending on the answer). In the formula ##E=\hbar \omega##, is E only kinetic energy or the total mechanical energy (kinetic energy plus potential energy). Thanks!
39. ### I 1 pm de Broglie wavelength? What's pm?

I'm reading about delayed-choice experiments http://arxiv.org/pdf/1407.2930.pdf and in this sentence "In modern interferometric experiments, the wave nature of molecules of approximately 7000 atomic mass units and 1 pm de Broglie wavelength has been demonstrated" I can't figure out or find out...
40. ### Experiment to measure frequency of de Broglie waves

Homework Statement Somebody knows an experiment to measure directly frequency of de Broglie waves?
41. ### I De Broglie Matter Waves: Where Does the Fraction Come From?

In de Broglie's original proof of the theorem of phase harmony, the frequency of the moving wave of energy mc^2 (not the internal periodic phenomenon wave) is multiplied by the following term ##freq * ( t - \frac{\beta * x}{c} ) ## Does anyone have an idea where the fraction comes from? All...
42. ### I Unit and dimension about De broglie wave

From the de Broglie wave formula we know, Rhamda=h/p In actual examples of course the answer would be 'something [meters]' I am having hardtime to understand how unit of h/mv [J*s]/[kg]*[m/s] turn into wavelength unit [m] I studied the Mass-Energy relation part earlier, But still can't get...
43. ### I De Broglie wavelength - relativistic correction

According to the wiki page: http://en.wikipedia.org/wiki/Matter_wave the generalised form for the de Broglie wave is simply: \lambda = h/p I suppose this not correct, because there is no trasform which can change only one side of the equation. In this case we have two variables: 1. a momentum...
44. ### A De Broglie Wavelength - Compound Particles, Particle Systems

Can someone describe the physical processes which distinguish between separate and single particles when dealing with a collection of particles in the context of the De Broglie wavelength? The De Broglie wavelength is inversely proportional to the momentum of a "particle". Assume "separate"...
45. ### I What specific momentum should be used in the matter wave?

According to de Broglie's hypothesis, the matter wavelength could be described by lamda=h/p. But which momentum, the classical p=mv, or the relativistic one p=mv(1-v^2/c^2)^(-1/2) should be used in this equation? Additionally, an even more confusing issue to me is regarding the other relation...
46. ### I The Debroglie Relation and SR?

The function ei(p.r – Et) is the central player in non-relativistic QM. Yet the expression (p.r – Et) is the Minkowski inner product of the space-time four-vector, (t,r), and the four-momentum (E,p) and as such is Lorentz invariant. According to Feynman, De Broglie realized the relativistic...
47. ### I Did de Broglie err in his hypothesis?

I'm a novice in this so to start with, I believe ... [mentor's note: a personal theory posted in violation of the Physics Forums rules has been removed from this post]
48. ### De Broglie Wavelength/Electron momentum

Homework Statement Homework Equations Einsteins photon momentum: p=h/wavelength (rearrange to get de broglie wavelength) The Attempt at a Solution I am quite new to all this quantum physics stuff. First of all where is the momentum of the electron reffering to its angular momentum when...
49. ### De Broglie wavelength and velocity

I was wondering about the equation for the de Broglie wavelength which indicates that the wavelength of any object is shorter when the object is moving faster. Why does this occur? And how we connect this with special relativity where the velocity depends on the frame of reference.
50. ### De Broglie about individuality and system

I've read De Broglie's book "La Physique Nouvelle Et Les Quanta" from 1936, which translates in "The New Physics and Quanta" but I haven't found the english version of the book (not sure it exists). This book looks over what you can learn during approximately the 2 first years of a bachelor in...