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. G

    Calculation of alpha particles from 226-Ra decay

    I am trying to solve the following problem for my graduate course in isotope geochemistry. If 1 g of 226Ra is separated from its decay products and then placed in a vessel, how much helium (cm3) will accumulate in the vessel in 60 days? Here is what I know. The decay series from 226Ra to Lead...
  2. N

    Electrons are not elementary particles?

    http://www.nature.com/news/not-quite-so-elementary-my-dear-electron-1.10471 Scientists have split an electron into 3 quasiparticles in the lab, why isn't this updated on the standard model?
  3. Toon

    Electric Forces with particles and Columbs law problem.

    Homework Statement Two particles, one with charge -7.13 × 10-6 C and one with charge 1.87 × 10-6 C, are 0.0284 meters apart. What is the magnitude of the force that one particle exerts on the other? Two new particles, which have identical positive charge q3, are placed the same 0.0284 meters...
  4. A

    Elastic collisions of particles

    Homework Statement Three particles, A, B, and C, with masses M, 2M, and 3M respectively, lie at rest in that order in a straight line on a smooth horizontal table. The particle A is then projected directly towards B with velocity U. Assuming the collisions are perfectly elastic, I need to find...
  5. C

    Negative amount of particles in statistical mechanics

    Suppose that you have N = \left(\frac{\partial U}{\partial \mu}\right)_{S,V} < 0, supposedly the number of particles, even though the actual number of particles is greater than zero. This means that you can have, in a system subjected to a grand canonical ensemble, less than 0 particle for...
  6. F

    Finding some quantities of particles moving relativistically

    Homework Statement A 2.5 MeV photon is moving in positive x-direction and an electron in the opposite direction at a velocity of 0.99c. Calculate their common total energy, momentum and total rest mass.Homework Equations Relativistic EquationsThe Attempt at a Solution I have some concerns...
  7. M

    Kinetic Energy of uranium particles

    Homework Statement A uranium-238 atom can break up into athorium-234 atom and a particle called an alpha particle, α-4. The numbers indicate the inertias of the atoms and the alpha particle in atomic mass units (1 amu = 1.66 × 10^−27 kg). When an uranium atom initially at rest breaks up, the...
  8. X

    Unit vectors for multiple particles? (Quantum Mechanics)

    It's been a little bit since I have studied multi-particle quantum mechanics and I am a little rusty on the notation. Let's say I have a wave function, that consists of the tensor product of two spaces, one for each particle moving, ##|\psi_1,\psi_2>##. Each of these particles is moving in a...
  9. M

    Solving for Charge of Particles on X-axis

    Hello everyone. Hopefully someone would be able to help me with this problem. The question states: Two point charges qa = -12 micro coulombs and qb = 45.0 micro coulombs and a third particle with unknown charge qc are located on the x axis. The particle qa is at the origin placed so that each...
  10. J

    Are photons really particles or just a misconception?

    Hello everyone, thanks for reading I'll explain my question. At first, light was described as electromagnetic waves, until Einstein proposed the photoelectric effect and thus creating the concept of photon, a particle of light with momentum and energy, but no mass. It could explain why the...
  11. D

    Finding magnitude and distance of a particles acceleration

    Homework Statement The figure depicts the motion of a particle moving along an x axis with a constant acceleration. The figure's vertical scaling is set by xs = 7.20 m. What are the (a) magnitude and (b) direction of the particle's acceleration ( +x or -x )? Homework Equations The Attempt...
  12. T

    Total mass-energy v nature of forces, particles

    What does the standard model have to say about the relationship between the total mass-energy of the universe and the characteristics of forces and force-carrier particles? That is, if the total mass-energy were different, would the nature, strength, … of the forces and force-carrier particles...
  13. D

    Particles Statics: Tension in Ropes & Angle Alpha

    Homework Statement Two tugboats are pulling a barge. if the resultant of the forces exerted by the tugboats is a 5000-lb force directed along the axis of the barge, determine (a) the tension in each of the ropes, give then alpha = 45 (b) the value for alpha for which the tension in rope 2 is...
  14. ComaBerenices

    Virtual Particles & the Casimir Force: Exploring the Link to Universe Expansion

    This is just a short question, it might have been asked already but I couldn't find anything. I read that we have attempted to reconcile the Casimir force with the observed expansion of the universe, doing this, we get a number 10^120 times too big. This is obviously a bad number to say the...
  15. I

    Number of elementary particles in an atom

    How Number of elementary particles in an atom are counted?
  16. TotalNovice

    B Speed of interaction between entangled particles

    When the spin of an entanglement particle is established, it is said that the corresponding spin of its entangled twin is revealed immediately, (via wave collapse?), and that this interaction can occur across a substantial distance. It has also been said that this immediate interaction can occur...
  17. Z

    Does exchange of identical particles lead to new state?

    Does an exchange of two identifical particles (electrons) lead to a new microscopic state?
  18. danihel

    Do hadron particles have half-life?

    Hi, i heard that as the universe will expand and the energy will grow sparse, in the end the matter itself will turn into radiation that will loose energy. So i wanted to ask, can a proton decay? and is it the same phenomenon as radioactive decay? Does it mean that even hydrogen (with no...
  19. G

    Interacting Quantum Field Theory: Ground State

    Hi all, I have a question about the ground state of an interacting quantum field theory. The state space in non-interacting QFT is a space where each field mode (with specified momentum p) has some occupation number n. These modes are interpreted as n particles with momentum p. The vacuum is...
  20. Vicol

    High-energy particles and Radiation burn

    Hello, it is my first post created in this forum :) I'm interested in physics of radiation burn. How does it work? In my opinion high-energy particles (like photons, neutrons etc.) leave their energy inside human body (for example breaking bonds in DNA). This event trigger primary electrons...
  21. MathematicalPhysicist

    Replacing the shape of the track of accelerator particles

    From what I can recall the shape of tracks of particle accelerator is circular. Is it possible to change this circular shape in future particle acclerators, to shapes like some knots (with more than one crossing)? to gain more distance in less space, I don't know how construct it, but it's a...
  22. Roy Stout

    Charged particles passing through a magnetic wave?

    Random thought... Is it possible for a charged particle to travel fast enough, or simply enter a magnetic field at just the right time in the magnetic wave's cycle, to pass through the magnetic field unaffected? If so, what is that calculation. If not, why not. Roy
  23. nnerik

    What is the problem with point particles?

    When I read about string theory, I sometimes get a feeling that the pointlike nature of particles in QFT is a problem that needs to be fixed, but I have never seen an explanation of the problem. Is this correct, and if so, why? Point in case (from https://en.wikipedia.org/wiki/String_theory)...
  24. Ryan Reed

    Why Do Some Particles Decay Faster Than Others?

    What is so unstable about one particle that it only lasts a billionth of a second? Opposed to another particle that lasts much longer. What is so different between the two and why are there "timers" set when these particles created?
  25. F

    What particles are black holes made of?

    What particles that constitute the black holes?Does normal particles constitute the black holes? How can we calculate the ratio of types of particles in the universe(we consider known matter but not consider dark energy and dark matter)?How can we calculate the total number of particles in the...
  26. Dilatino

    Demystification of the spin-sum for massive spin-1 particles

    Assuming that a massive spin-1 particle has momentum only in the z-direction, the polarization vectors are given by \varepsilon_{\mu}(J_z = +1) = (0,-\frac{1}{\sqrt{2}},-\frac{i}{\sqrt{2}},0 ) \varepsilon_{\mu}(J_z = 0) = (\frac{p}{m},0,0, \frac{E}{m}) \varepsilon_{\mu}(J_z = -1) =...
  27. J

    Can Electron Teleportation Occur in Small Time Intervals?

    If we measure the location of an electron in atom once and then again instantly, we would cause the collapse of the wave-function twice in some time interval and the object has a probability of being in a distanced location in regard to the location of previous measure (for example, we measure...
  28. M

    Can the equation E = pc be applied to particles?

    Homework Statement Can the equation E = pc be applied to particles? Why or why not?Homework EquationsThe Attempt at a Solution It can be applied to particles that DONT have a rest mass (photons, which are particles). It can not be applied to particles that have a rest mass (almost everything).
  29. M

    Electric fields, particles and deflection

    Homework Statement Explain the circumstances that enable a particle to move un-deflected with uniform motion through an electric field if it is given an initial velocity perpendicular to the electric field. Assume the electric field is the only field present.[/B] Homework EquationsThe Attempt...
  30. L

    Motion of charged particles in electric and magnetic fields

    Homework Statement 1) Describe and explain what happens to the electron beam on the screen of a teltron tube as the EHT(electrical high tension) voltage increases from 3000V to 3500V. 2)What is the effect of E field on light waves? Homework EquationsThe Attempt at a Solution 1) The beam...
  31. N

    Fundamental point like particles?

    Is it possible that fundamental point like particles (ie electrons) are actually particles with shape size and structure that are too small for any of our current technology to detect?
  32. Akhilesh Kumar

    Why do particles have charge?

    We have been able to explain the reason for the mass of a particle to a great extend... But till now why are we not getting a clear idea of why does a particle has charge?? What gives a particle its charge??
  33. Ryan Reed

    Are there Quark-Antiquark Particles?

    There are exotic atoms such as the protonium (proton+antiproton) and positronium (electron+positron); I was wondering if quark-antiquark particles could appear even if they only exist for a fraction of a second.
  34. N

    What if elementary particles do have size

    Is it possible that they have the structure something like we used to picture them as? For example, what if we captured an electron and zoom in with a microscope that see infinitly small distances. Is it possible that if we zoomed into the electron close enough that we would see an object...
  35. S

    Are particles lost during fusion?

    Hi simple question here, I was wondering if matter (actual particles) are lost from the fusion process.
  36. L

    How 2 particles become entangled?

    I don't have clear how two particles initially "independent" in the sense of "not entangled" become then entangled because of their mutual interaction (and in this last case, when and how I can say they "interact"?). How do I know how should they approach or how strong their interaction should...
  37. SpiderET

    I Particles with mass can't reach speed of light?

    One of the important predictions of relativity theory is that particles with mass can't reach speed of light in vacuum and will always be slightly slower. I wanted to know more about the maximum speed which can be reached by particles with mass and looked for relevant experiments. But to my...
  38. tomdodd4598

    Spin Matrices for Multiple Particles

    I have two questions, but the second is only worth asking if the answer to the first is yes: Are the spin matrices for three particles, with the same spin, σ ⊗ I ⊗ I, I ⊗ σ ⊗ I and I ⊗ I ⊗ σ for particles 1, 2 and 3 respectively, where σ is the spin matrix for a single one of the particles? I...
  39. S

    A Problem about representations of group and particles

    I'm reading a paper these days, How can I get 2.28? It seems for a D-dim SO(2) gauge field, we have spin2, spin1, as well as spin0 particles?
  40. tomdodd4598

    Eigenstates of 3 spin 1/2 particles

    Hi, I have learned about how to find the 4 spin states of 2 spin 1/2 particles, and how to find them by using the lowering operator twice on |1/2, 1/2> to find the triplet, then simply finding the orthogonal singlet state, |0, 0>. I started to attempt finding the states of 3 spin 1/2...
  41. newjerseyrunner

    The Uncertainty of Time in Quantum Mechanics

    I was thinking about the double slit experiment and I know that if you let electrons go through one slit on the other it'll produce a pattern like a particle and if you let it go through both it'll act like a wave. I also know that if you observe the electron at the hole, the ones you observe...
  42. T

    What is a good book to learn particles?

    I'm interested in learning about standard model, and particles. What's a good book to learn from? I have taken some college physics classes. Thanks!
  43. Coffee_

    BEC question about number of excited particles

    Assuming no interactions, and the energy levels ##\epsilon_j## for a single particle state, the occupation number for this state for a system of particles is given by: à ##n_j=\frac{1}{exp(\frac{\epsilon_j-µ}{kT}) - 1}## (1) (Here comes argument 1) We conclude that the maximal value that µ...
  44. meyol99

    Describe movement of particles with one equation?

    Hello everybody, I have a new thread to post,it is very important to find a solution for this : -Imagine a box full of air particles.The particles are forced to move to a point A on the edge of the box.My question is now,how can I mathematicly describe the movement of these particles toward...
  45. S

    How fast do subatomic particles move?

    what might be the speed of subatomic particles ? The problem arises from all the interactions of subatomic particles are known to be super fast . thus wish to know how fast they are . Does time have anything to do with subatomic particles ? ( Relativity ) " am a science enthusiast just out of...
  46. DeathbyGreen

    Question of spin 1/2 particles in a rotating field

    Homework Statement So I'm given a spin 1/2 particle in a rotating magnetic field in the (x,y) direction and a constant field, B_0, in the z direction and am asked to find the S matrix describing it. Given is: B(t) = [B_1 \cos(\omega t), B_1 \sin(\omega t), B_0] Homework Equations H = \sum...
  47. Superleopard21

    Will two particles never touch each other?

    i found that in the 3 W-W exchange of 4-fermion interaction of weak decay of Neturon beta-decay process and also this happens in scattering process,is there will be a gap or a channel between two particles?
  48. C

    Wave function of multiple particles

    I've got a question for you all. if there is a wave-function for a single particle, such as a photon.. and there is a wave-function for an electron.. "A wave function in quantum mechanics describes the quantum state of an isolated system of one or more particles. There is one wave function...
  49. B

    Do Particles at LHC Travel Near Light Speed?

    If particles at the LHC are traveling very near the speed of light, are they affected by the slowness of time? Also, how can they travel near the speed of light when the planet is rotating around the sun and the solar system is traveling around the galaxy and the galaxy is moving through space...
  50. olgerm

    Schrödinger equation for 2 particles

    U(x,y,z,t)*ψ(x,y,z,t)-(ħ/(2*m))*(d2ψ(x,y,z,t)/dx2+d2ψ(x,y,z,t)/dy2+d2ψ(x,y,z,t)/dz2)=ħ*i*dψ(x,y,z,t)/dt qproton=-qe Schrödinger equation for electron in hydrogen atom (if we consider proton as point charge which is moving at a constant speed vproton→=(vp;x;vp;y;vp;z).) is...
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