What is Particle: Definition and 1000 Discussions

In the physical sciences, a particle (or corpuscule in older texts) is a small localized object to which can be ascribed several physical or chemical properties such as volume, density or mass. They vary greatly in size or quantity, from subatomic particles like the electron, to microscopic particles like atoms and molecules, to macroscopic particles like powders and other granular materials. Particles can also be used to create scientific models of even larger objects depending on their density, such as humans moving in a crowd or celestial bodies in motion.
The term 'particle' is rather general in meaning, and is refined as needed by various scientific fields. Anything that is composed of particles may be referred to as being particulate. However, the noun 'particulate' is most frequently used to refer to pollutants in the Earth's atmosphere, which are a suspension of unconnected particles, rather than a connected particle aggregation.

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  1. aligator11

    Particle Dynamics Problem (kinematics)

    Summary: Mechanics problem related with Calculus (differential equations) Hi everyone, I would like some help in that task, if anyone would be willing to help :) Namely I have a problem from particle dynamics. "D:" means given info... so, D: m,g,h,b, miu. We're looking for v0 and S as given...
  2. S

    B My particle simulation version of the Double Slit experiment

    I created this in java just a while ago.
  3. X

    B Can we produce black holes by particle accelerators?

    Summary: Thanks to CERN, we now have huge particle accelerators such as the LHC. We use them to enhance our understanding of quantum physics. As everyone know,particle accelerators are huge machines that smashes atoms into pieces at near the speed of light. I have heard making antimatter by...
  4. K

    I Is a neutron a separate particle or compound?

    In many physics fields, the neutron is considered as a separate particle? But the neutron decays into a proton and an electron. Why is it considered an independent particle? Although the fact of decay suggests that the neutron is a composite particle.
  5. fight_club_alum

    Particle in a circular path due to magnetic field

    v = sqrt( (2 * charge of proton * 3000/e) / (mass of proton)) v = 1.893986024 x 10^`15 r = ( (mass of proton) * (velocity) ) / ((magnetic field) * (charge of proton)) r = 24715769.68 m Anyone please help
  6. fight_club_alum

    Particle that moves in an electric and magnetic field

    m = 0.005 q = -70 x 10^-6 c v = 30,000 m/s Since there is no movement vertically Fb = Mg So, q . V . B = mg So, (70 x `10^-6) . (30,000) . B = (0.005) . (9.8) So, B = 0.0233333 or ~ 23 MT
  7. fight_club_alum

    Find the charge of this particle moving in a magnetic field

    F = ma F = (6x10^-6) * 8 F = 4.8 * 10^-5 F = QBVsin(theta) F/(BVsin(theta) = Q (4.8 x 10^-5) / (5 x 10^-3) (4000) (sin(37)) = 3.98 x 10^-6 ~ 4 uc <---- THE RIGHT ANSWER IS -4 uc
  8. fluidistic

    How to mathematically write down a probability of measuring a particle

    Consider a system of 2 identical electrons that are confined in a region so that there is a single wavefunction describing the whole system. In several textbooks one can read that the probability to measure the position of an electron in region near ##r_1## and the other in a region near ##r_2##...
  9. W

    Particle Would like some particle physics textbook-reading advice

    Hi all, I am in a bit of a funny situation where I need to pick up at least a cursory knowledge of QFT and particle physics in the space of two weeks. I borrowed "QFT and the Standard Model" by Schwartz but I have no idea how I should approach it. Ideally I'd pour through every page, but I...
  10. B

    I Parallel plate particle acceleraton questions

    Suppose there exists a pair of parallel plates with a voltage between them. These plates have a certain amount of energy stored in the electric field between them (E=1/2*C*V^2). Now we fire a fast (~5,000,000 m/s) beam of protons through the plates (parallel to the electric field) such that the...
  11. Zeynaz

    How Does Particle in a Box Relate to Quantum Mechanics?

    I am having difficulties understanding this concept. Particle in a box (as far as i understood) shows that the electrons or particles need a certain about of potential energy to escape the one-dimentional potential well. I think its pretty similar to the concept of the electons and ionising...
  12. Hypervalent_Iodine

    How does the missing + sign in the equation affect the trajectory of a particle?

    Can someone explain how can i get that answer?
  13. Silvio Macedo

    I Wave function of particle / quantum field in space, also in time?

    Quantum fields have wave functions that determine a particle position in space. It solves non-locality, double-slit paradox, tunnel effect, etc. What if the wave function is also in time? Won't it solve the breaking of causality at quantum level? (Delayed Choice/Quantum Eraser/Time) Not much...
  14. Celso

    Particle in a "roller coaster"

    I first found ##v_{B}## by ##E_{p,A,B} = mgh_{1} = E_{c, B} = \frac{1}{2}mv_{B}^2 \therefore v_{B} = \sqrt{2gh_{1}} ## After this I made several failed attempts basically trying to find its final velocity so I could use conservation of energy. Spliting the velocity into its components never...
  15. BobbaD

    I Can Particles Defy Time by Reaching Below Absolute Zero?

    Could a particle be sent back in time on it's world line? Time is defined by events, but at absolute zero, there is no movement or vibration of a particle - does not time cease to pass then at absolute zero for the particle? If the particle was somehow brought below absolute zero, could it be...
  16. K

    Velocity of a charged particle

    Hi. I will be glad if you can help me with a small problem. I got a cylinder with a density $$ \rho (r) = b \cdot e^{\lambda r} $$, with radius $$ R $$. If I let go a charge q < 0 from $$ R_0 $$ when $$ R_0 > R $$ , what will be the velocity that the charge will hit the axis of the cylinder.So...
  17. J

    A Classical particle in a 2D box

    I am trying to understand ergodic theory, i.e. how simple systems reach equilibrium. I consider a classical particle in a 2D (or 3D) box. Funnily, I have never seen this example in books (probably due to lack of knowledge). Instead, in QM, the particle in a box is a prototypical example. My...
  18. K

    I Confused about particle interactions

    Hello! As far as I understand, in QFT the interaction between particles is mediated by the exchange of a boson. When doing calculations, one assumes that you have 2 free particles coming in, they interact at a point by exchanging a boson and then they propagate again as free particles, and this...
  19. R

    B Particle properties conclusion from no-slit diffraction

    Is it possible to infer particle properties from 2 sources diffraction with no slit/slits involved? Some explanations of experiments i can find, if i understand them correctly at all, relate to the possibility of concluding particle momentum, from absorption lines, when emanating from a single...
  20. M

    I Why not a particle for charge?

    I was recently seeing videos on standard model of particle physics and something occurred to me that ,Higgs field gives mass to elementary particles ,this gives reason for one property of matter that is mass. Why not a field that gives elementary particles a charge ? After all their are two...
  21. B

    B So can I use "wave particle duality?"

    Some sources say wave particle duality is very much a principal, others say it's oversimplified and not exactly true but still okay to use in order to explain things, and many say it's flat out wrong... so who's right? Can I say "wave particle duality" when talking quantum mechanics or no?
  22. RicardoMP

    How to determine particle energies in center of momentum frame?

    That said, my approach was to determine the energies and 3-momenta at the center of momentum reference frame for each particle, with a fixed s, and check it corresponds to each one of the above, but I'm having some trouble proving that, for example, E_A=\frac{s+m^2_A-m^2_B}{2\sqrt{s}}. I've...
  23. F

    I Particle in a box experiment confirmation

    Is there any experiments that validate the results of particle in a box with infinite or finite potential. Thanks
  24. remormalise

    I Unveiling the Mystery of Entangled Particle Spin

    If you change the spin of an entangled particle without knowing its original spin, what happens to the other entangled particle?
  25. JD_PM

    Particle moving in conservative force field

    I don't get why ##F \cdot dr = \frac{mv^2}{2}## I know this has to be really easy but don't see it. Thanks.
  26. Haorong Wu

    The position and momentum operators for a free particle in Heisenberg picture

    Homework Statement From Griffiths GM 3rd p.266 Consider a free particle of mass ##m##. Show that the position and momentum operators in the Heisenberg picture are given by$$ {\hat x}_H \left( t \right) ={\hat x}_H \left( 0 \right) + \frac { {\hat p}_H \left( 0 \right) t} m $$ $$ {\hat p}_H...
  27. S

    Solving Particle Motion in a Rigid Box: t=0

    I have question, how can I solve problem of particle in rigid box when one of the wall gets completely destroyed? At time t = 0 the right wall of box gets completely destroyed, left wall is still here( ψ(0) = 0 ), also at t = 0 we know that particle is in ground state. How can I search for...
  28. A

    Fluid Mechanics, Particle Size, Bouyouncy Force

    1. What should be the size of object/Particle (sphere) so that it should remain suspended (neither it should sink nor it should float)? container dimensions 30*25*25, density of fluid 0.9g/cm3 , density of particle 0.86g/cm3 , particle is coated with aluminium having density of 2.07g/cm3.(if...
  29. F

    Motion Homework -- A particle moving along the x-axis....

    Homework Statement The position function x(t) of a particle moving along an x axis is x = 6.00 - 7.00t2, with x in meters and t in seconds. Homework Equations (a)[/B] At what time and (b) where does the particle (momentarily) stop? At what (c) negative time and (d) positive time does the...
  30. fight_club_alum

    Electric Potential slowing a charged particle to a stop

    Homework Statement A particle (mass 6.7 × 10–27 kg, charge 3.2 × 10–19 μC) moves along the positive x-axis with a speed of 4.8 × 105 m/s. It enters a region of uniform electric field parallel to its motion and comes to rest after moving 2.0 m into the field. What is the magnitude of the...
  31. Alan Ezra

    I Particle in a box and quantization of energy

    Greetings, In the scenario of a particle in an infinite potential well, there are discrete energy levels, i.e.##E=\hbar ^2 n^2 \pi ^2/ (2 m L^2)## where L is the width of the potential well, and n takes on positive integers. But what will happen if I put a particle of energy ##E_i## that is not...
  32. S

    Admissions PhD in Particle Physics: Oxford or Imperial?

    Hi all, I recently got accepted to do a PhD into High Energy Physics groups at Oxford, Imperial, UCL, Cambridge and Manchester. My main interest is neutrino physics, which all of these places are offering. However, I am struggling to pick between Oxford and Imperial. I have met and discussed...
  33. S

    Studying Minimal preliminary knowledge for a PhD in particle physics?

    Currently, I am doing a master in mathematical physics. I am interested in particles& field theory and want to apply a PhD in this field. But I am not sure whether I can... I just learned a little high energy physics from Griffth and Peskin' book on elementary particles and QFT. Recently, I...
  34. Nathan Warford

    B Significance of the Planck Particle

    Taken from the Wikipedia page: Is there something significant about the physics of the Planck Particle or its properties? If so, then what is the significance? If there's nothing especially significant about the Planck Particle, then you can just say "No" and I will consider the matter closed...
  35. L

    A Quantum amplitude for a particle falling into a black hole

    Here we consider a black hole formed by gravitational collapse classically. We also consider a scalar massless Klein-Gordon field propagating on this background. To quantize the field we expand it in appropriate modes. The three sets of modes required are: The incoming modes, appropriate for...
  36. S

    B Does Entangled Particle Detection Prove the Spooky Action at a Distance?

    My question about quantum entaglement is: is a Quantum particle's spin [altered] into another spin position at the moment of detection or is it just a 'snapshot picture' of the spin at the moment of detection (without alteration)? It seems this is an important differentiation. If there is no...
  37. D

    I Parity operator and a free particle on a circle

    Hi. I have just looked at a question concerning a free particle on a circle with ψ(0) = ψ(L). The question asks to find a self-adjoint operator that commutes with H but not p. Because H commutes with p , i assumed there was no such operator. The answer given , was the parity operator. It acts...
  38. R

    I Boltzmann particle distinguishability

    What justifies the use of multinomial coefficient in the combinatorics used by Boltzmann? The particles are distinct but counts as identical when they are in the same energy state?
  39. S

    I Interpreting SM Lagrangian "differential particle" terms

    The Standard Model Lagrangian contains terms like these: ##-\partial_\mu \phi^+ \partial_\mu\phi^-## ##-\frac{1}{2}\partial_\nu Z^0_\mu\partial_\nu Z^0_\mu## ##-igc_w\partial_\nu Z^0(W^+_\mu W^-_\nu-W^+_\nu W^-_\mu)## How should one interpret the "derivative particle fields" like...
  40. E

    I Advancements in Cyclotron Particle Accelerator Design: A Scientist's Perspective

    I've been working on modifying the cyclotron particle accelerator. Tell me what you think? It's pretty basic though
  41. A

    What is the magnetic field generated by these two particle beams?

    A uniform beam of positively charged particles is moving with a constant velocity parallel to another beam of negatively charged particles moving with the same velocity but in opposite direction separated by a distance d. Then, how should be the variation of magnetic field B along a...
  42. brotherbobby

    Alpha Particle Scattering and angular momentum

    Statement of the problem : "Using the definition L = r ##\times## p, prove that the direction of L is constant for an alpha (##\alpha##) particle whose scattering is shown in the diagram below. " Relevant equations : We are aware that the scattering takes place via a central force F = F(r)...
  43. K

    I Acceleration of a relativistic particle

    In an inertial frame, consider that a particle's position and the time measured by a clock in this frame are respectively, ##(t,x)##. Suppose there's another frame, moving with constant speed ##v_R## with respect to the frame described above. The particle acceleration is given in the first...
  44. Edge5

    I Making World's Smallest MEMS Accelerometer

    Hi everyone. I want to make a very small accelerometer. (A micro or nanosized MEMS accelerometer) What do you think about this idea? I will have a source which will emit alpha particles. I will place two movable magnets at both sides of the alpha particle. When I apply acceleration to the...
  45. A

    B Is it possible to change a fundamental property of a particle?

    Is it possible to change a fundamental property of a particle? If that can be done, will it's twin particle's state also be altered accordingly?
  46. FourEyedRaven

    I Particle Physics vs Quantum Field Theory vs Standard Model

    Hi. I'd like to ask what are the differences between Particle Physics, Quantum Field Theory and the Standard Model. I see these names of physics courses but I want to confirm if I understand the difference. My understanding is that when students learn particle physics in their undergraduate...
  47. Mutatis

    Net force acting on a charged particle ##+Q##

    Homework Statement Twelve equal particles of charge ##+q## are equally spaced over a circumference (like the hours in a watch) of radius R. At the center of the circumference is a particle with charge ##+Q##. a) Describe the net force acting over ##+Q##. b) If the charge located at...
  48. S

    Calculus Problem: acceleration, speed, and displacement of a particle

    Homework Statement The acceleration of a particle given a=A√t where A=2.0 m/s5/2. At t=0, v=7.5 m/s and x=0. (a) What is the speed as a function of time? (b) What is the displacement as a function of time? (c) What are the acceleration, speed, and displacement at t=5.0s. Homework EquationsThe...
  49. D

    Trajectory of a particle when its position vector changes

    Homework Statement The position vector of a particle changes: Only by its module. Only by its direction. What can be said about the trayectory of the movement of the particle? Obtain the answer analitically. Homework Equations None. The Attempt at a Solution I think that the trayectory...
  50. L

    I Massive Particles in Sonic & Slow Light Black Holes

    I am working on a research project where I intend to describe what the Penrose process would like in a sonic black hole. I have found what a rotating (Kerr) black hole looks like in the sonic analog: https://arxiv.org/pdf/1802.08306.pdf I have also found that the analog of massless particles...
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