What is Particles: 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. R

    I Are some elementary particles too massive to obey QM?

    I understand photons and elections fit into the probalistic rules of QM. Are there any other elementary particles (more massive) that don’t obey the point/wave duality?
  2. A

    B Virtual Particles and nothingness

    According to what I have read and watched (I am new to the subject) the empty space is actually full of temporary virtual particulars that spontaneously and continuously emerge from nowhere and then disappear from the nothingness again but from where comes so much energy for so much creation of...
  3. N

    I Motion of Null, Timelike & Spacelike Particles

    For a null particle, ds^2 = 0, Timelike, ds^2 >0, spacelike, ds^2 < 0, how would you characterize the motion of each particle?
  4. O

    I From Indistinguishable to Completely Identical Particles

    Is it possible to take two identifiably different particles of the exact same type (I previously called them indistinguishable in error?) which have different quantum states (say a different distribution in position or momentum Hilbert space) and physically cause them to have identical states...
  5. Andrew Lewis

    Thermal Physics: Photon Statistics on Bose Particles

    Homework Statement [/B] I have solve the rest of this problem pretty easily and see no problems with working with Indistinguishable particles, Distinguishable particles, fermions and Bosons. Part c has me very confused though about what it is even asking. Suppose a system with equally spaced...
  6. Akash47

    What is the Electric Field at a Point Surrounded by Infinite Charged Particles?

    There are infinite number of charges each with charge q along a straight line at a distance of 1,2,4,8,16,… … … unit from a point. What is the electric field at this point? No idea about it.Please help me out.
  7. D

    Dave Parham, Raleigh, NC, I love Science

    hi there, i have always loved Science, and from astronomy transitioned into particle physics because of the Higg Boson, learning about the implications of Dark Matter, and Dark Energy. i am also studying things like Zero Point Energy, have always been fascinated with the flight dynamics of...
  8. Decimal

    I Value of orbital angular momentum for two particles

    Hello, I encountered the following statement in my lecture notes and there is a couple of things I don't understand:"Let's consider two particles with spins ##s_1 = \frac{1}{2}## and ## s_2 = 1## with a spherically symmetric interaction potential. Assume these two particles are in a two...
  9. S

    Kinetic Energy for particles (alpha decay)

    Homework Statement Many heavy nuclei undergo spontaneous "alpha decay," in which the original nucleus emits an alpha particle (a helium nucleus containing two protons and two neutrons), leaving behind a "daughter" nucleus that has two fewer protons and two fewer neutrons than the original...
  10. M

    Elastic collision with particles, find the kinetic energy

    Homework Statement A proton strikes a stationary alpha particle (4He nucleus) head-on. Assuming the collision is completely elastic, what fraction of the proton’s kinetic energy is transferred to the alpha particle? Homework Equations Pi = Pf Ki = Kf The Attempt at a Solution Tried finding...
  11. S

    Is Constant Linear Velocity Possible in Rotating Particles?

    If talking about a particle rotating around an axis away from it by r. if the particle is moving with constant angular velocity ω. is the linear velocity constant or no? Now what I know is that since we have Vt= ωr, so r doesn't change, as well as ω, so Vt is said to be constant. but I think...
  12. nomadreid

    I Infinite range of E-M field vs finite age of particles

    It is said (hopefully no need to give references for such a common statement) that the electromagnetic field of a given charged particle is infinite in range (albeit converging to zero as the distance goes to infinity). However, given that charged particles apparently did not exist at the...
  13. G

    I Where are the Beta Particles in a Muon Detector?

    This may be a pretty basic question ,but i'll through it out any way. As a project i built a muon detector from 2 matched PMTs and 2 4x6x1 plastic PVT scintillators. And pulse processing NIM modules. I was getting pretty good coincidence reading,some what less than predicted.ie ( 1...
  14. C

    -- The drawing shows three particles far away from....

    The drawing shows three particles far away from any other objects and located on a straight line. The masses of these particles are mA = 340 kg, mB = 567 kg, and mC = 139 kg. Take the positive direction to be to the right. Find the net gravitational force, including sign, acting on (a) particle...
  15. D

    Accelerating charged particles and conservation of energy

    Hi I'm wondering how when a charged particle is accelerating it both emits energy in the form of em radiation while also gaining kinetic energy. All of that energy comes from the thing accelerating the charged particle, yeah? Is that necessary, like it is not possible to give a charged particle...
  16. Amrator

    I LHCb Discovers Two New Particles

    https://home.cern/about/updates/2018/09/lhcb-experiment-discovers-two-perhaps-three-new-particles http://lhcb-public.web.cern.ch/lhcb-public/Welcome.html#LHCCCKM This is very exciting news! What exactly does it say about the strong interaction?
  17. H

    I What does it mean for particles to be "far apart" in QFT

    I'm currently reading Schwartz's QFT text "Quantum Field Theory and the Standard Model" (although this question does not specifically pertain to this text) and I've got two questions: 1. At the beginning of chapter 6 he talks about how we may consider the system to be non-interacting in...
  18. opus

    Characteristics of a particles path- v(t) and a(t)

    Homework Statement Please see the attached images. The position of a particle moving along a coordinate axis is given by ##s(t) = t^3-9t^2+24t+4## where t is greater than 0. a) Find v(t) b) At what time(s) is the particle at rest? c) On what time intervals is the particle moving from left to...
  19. M

    Elastic collision in one of the particles' frame

    Homework Statement A particle B is standing still while another one, A, is moving towards it with initial 4-momentum ##(E,p,0,0)##. Calculate the change in particle A's 4-momentum as viewed from the particle B's rest frame, in terms of the initial energy E and the scattering angle ##\theta##...
  20. Z

    B LHC Collisions: Events, Energy & Finding New Particles

    What do ‘events’ refer to when collisions occur at the LHC. The Higgs Boson was found from a blip in the graph of Events vs Energy at about 125Gev. It shows an excess of events at this energy. But what events are in excess and why does this indicate the existence of a particle?
  21. Marco DF

    B What is the Role of Sub-Particles in the Existence of Matter?

    Hi everyone! Here the question(s). In the vacuum, the sub particles pop up and down (annihilation). If this is right, we can tell that the all matter is the attempt of sub particles to remain alive? so, is my glass of wine a desperate attempt of electrons, quarks, and all the other particles...
  22. Nevada City Bob

    I Bosons: Explaining Particles That Defy Imagination

    I've never been able to get my head around the idea that forces are particles. In the case of fermions, a particle seems to be a natural concept. Even though it's really a wave, or an excitation in a quantum field, I can envision it as being something in a particular place. For bosons that...
  23. BeyondBelief96

    What Angle Causes Particles A and B to Collide?

    Homework Statement A particle A moves along the line y = d (30 m) with a constant velocity (v= 3.0 m/s) directed parallel to the positive x-axis (Fig. 4-40). A second particle B starts at the origin with zero speed and constant acceleration (a = 0.40 m/s2) at the same instant that particle A...
  24. Deepblu

    I Why are all particles of the same type identical?

    Why all particles of same type identical? All electrons are identical to each other, all protons are identical..etc. It is as if they are copy pasted from each other! For me this is one of the biggest mysteries ever, why we don't detect more massive or less massive electrons? Is it related...
  25. S

    Statistical physics question - particles in a magnetic field

    Homework Statement [/B] I'm stuck on part (b) and (c) of the following question Homework Equations The Attempt at a Solution The partition function was ##Z_N = 2 cosh(μBβ)## where ##β = \frac {1}{kT}##. From there I used ##U = - \frac {∂}{∂β} ln (Z_n)## to get ##U = -NμB tanh( \frac...
  26. K

    I Standard boost, particles with mass M > 0

    Weinberg considers (p.68 QFT Vol. 1) particles with mass M > 0. The Little Group is SO(3). He wants to calculate the rotation W(Λ,p) ≡ L-1(Λp) Λ L(p). He says that for this we need to choose a standard boost L(p) which carries the four momentum from kμ = (0,0,0,M) to pμ. He then shows the...
  27. A

    Simple harmonic motion of charged particles

    Homework Statement Two identical particles, each having charge +q, are fixed in space and separated by a distance d. A third particle with charge -Q is free to move and lies initially at rest on the perpendicular bisector of the two fixed charges a distance x from the midpoint between the two...
  28. A

    A Vacuum in interacting QFT and physical particles

    After some reading, I'm quite confused about the vacuum state in interacting QFT. I've read the @A. Neumaier post on "The Vacuum Fluctuation Myth," where he notes that "bare quantum field theory with a cutoff, the vacuum is a complicated multiparticle state depending on the cutoff – though in a...
  29. R

    B In the beginning, how did elementary particles form?.........

    ... and how were these then able to go on to form atoms?
  30. J

    B Identification of sub atomic particles?

    I have not formally studied physics but am interested in quantum physics. I have studied calculus so I know a little bit about mathematics in case the answer requires it. My question is, when a physicist conducts experiments at the quantum level, how do they know that what they are "seeing" is...
  31. A

    I Identity Operator for Multiple Particles

    Hi, For a particle in a box (so that the momentum spectrum is discrete), we can write the identity operator as a sum over all momentum eigenstates of a projection to that eigenstate: $$I=\displaystyle\sum\limits_{p} |p\rangle\langle p|.$$ I was wondering what the corresponding form of the...
  32. G

    A Charged particles mass before symmetry breaking

    How could electrically charged particles be massless before the symmetry breaking? Wouldn't the energy stored in the electric field contribute to particles mass?
  33. HCverma

    What does it mean by 'number of particles in a substance'?

    Homework Statement If, N = n × NA Where N = Number of particles in the substance and n = Amount of substance in moles (mol) and NA = Avogadro Number = 6.022 × 1023 particles mol-1 To find the number of particles, N, in a substance: N = n × NA To find the moles, n, of substance, n = N ÷ NA...
  34. L

    I Particles more fundamental than fields

    In this Nima Arkani-Hamed paper on page 5 I found the sentence: These constraints are an artifact of using fields as auxiliary objects to describe the interactions of the more fundamental particles. In Schwartz's QFT book I also get away with the impression that the Poincaré irreps (i.e...
  35. F

    I Decorrelate 2 particles initially entangled

    Hello, I am studying the entanglement in quantum physics, especially the Aspect's experience where 2 photons initially correlated keep this correlation through the measure of their polarity. The Wikipedia article is only available in French, but there is an article in English written by Alain...
  36. LarryS

    I Do identical particles really exist?

    The concept of Identical Particles in non-relativistic QM seems a little shakey to me. All elementary particles of a certain type, say electrons, are supposed to be identical except for a handful of degrees of freedom like spin direction, position, etc. (For some reason, energy and momentum...
  37. BadgerBadger92

    B Are electrons virtual particles?

    Since electrons pop in and out of existence, are they virtual particles?
  38. BadgerBadger92

    How is light related to charged particles?

    I did a little more research, please clarify. So the electric field is directed to the proton and that emits light? Can you get into more detail? I am not educated in math so this is hard to understand at this point. I understand how electrons emit light but not protons. So is the magnetic...
  39. I

    I Invariant mass plots for resonance 'particles'

    The interaction p + π- → n + π- + π + may proceed by the creation of an intermediate 'particle' or resonance called a rho. This can be detected as a peak in the plot of invariant rest mass energy of the emergent pions versus frequency of pions observed. My question is quite simply, invariant...
  40. R

    How do plasma particles interact with a magnetic field?

    How does plasma particles (ions, electrons, neutral particles as a whole) interact with an applied steady-state magnetic field? If you have plasma at atmospheric pressure ejected from a plasma torch in the z-axis direction (upwards/north), how will two permanent magnets, axially aligned N-S to...
  41. bland

    B Understanding Particle Motion in Deep Intergalactic Space

    I hear that deepest void of intergalactic space may contain say one particle per cubic cm. I don't want to quibble the amount but let's take that as close enough for my purposes. Now is this figure a statistical average so that if it were correct that each cubic kilometre of deep space would...
  42. R

    I Do elementary particles experience gravity?

    For example, do electrons, atoms etc. experience gravity? Is this proved by experiment?
  43. Ericdjs

    Is it correct to calculate the number of particles

    I want to calculate that how many particles will be recorded by detector with MCNP. using the F8 tally which would provide energy spectrum, add all of data that related with full energy peak of spectrum, multiply by number of nps, then obtain the number of particles. is it correct ? i am not...
  44. Kenneth Boon Faker

    A question about wave/particle duality

    Subatomic particles can take the form of a wave or a particle. While in wave form, it is not like a physical wave, but rather a probability wave, (i.e. a wave of information about where the particle is probably located etc.) And while in particle form, a photon, for example, can knock electrons...
  45. RosutoTakeshi

    Superman created virtual particles?

    Comic is Superman/Batman #80 Superman explains that virtual particles are always spontaneous generated And that he's using his heat vision to (excite) the vacuum in order to accelerate the process. He's generating more virtual particles So my question is, how much energy or heat did...
  46. Cocoleia

    Position of particles on a detector after decay

    Homework Statement A hypertriton (a bound system with a L hyperon together with a deuteron core (proton and neutron) is produced at the origin of the coordinate, (x,y)=(0,0) with a velocity of 0.94c (beta=0.94), flying along the x-axis. The mass of the hypertriton is 2.991 GeV/c2 . It decays...
  47. facenian

    I Deriving GHZ Theorem for 3 Particles: A Detailed Guide

    Where can I find a detailed derivation for GHZ theorem for 3 particles?
  48. Malek

    B Speed of Light & Virtual Particles: Is There a Connection?

    Are there any relationships between the speed of light and the virtual particles in the vacuum? I mean that, Can I call it as a medium of propagation of a light beam?
  49. Dadface

    I There are no particles, only fields

    It seems to be widely accepted on this forum that fields, not particles, are fundamental. In other words particles are made of fields. I have seen particles described in various ways such as being excitations of fields or eigenstates with known energy. This creates a problem for high school...
  50. H

    Find the minimum distance between 2 particles

    Homework Statement A point particle of mass m and charge q(>0) approaches to a point particle Q(>0) at a fixed position. When the distance between the two particles is L, the speed of the moving particle is v. The permittivity of the vacuum is denoted as Epsilon0. Find the minimum distance...
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