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. Nikhil Rajagopalan

    Work done by internal forces on a system of particles

    Dear Experts, Trying to analyze the work done by internal forces in a very simple two particle system which is attracted to each other with a constant force, i performed calculations based on two frame of references, 1.The center or mass frame of reference and 2. Frame of reference of one of the...
  2. R

    I Matter/antimatter collisons between "unlike" particles?

    Just about everything I have read about antimatter talks about proton/antiproton, electron/antielectron, and neutron/antineutron annihilation. But what happens if, for example, a proton and an antineutron collide? Would a weird nucleus be created or would there be a partial annihilation...
  3. Hose way or joshua

    B What particles make up an atom?

    I'm trying to find a way to understand Q.P. So far I know that each element contains as many protons as it does nuetrons or electrons. Is that right? Derp lol
  4. H

    Defining magnetic interaction between charged particles

    Homework Statement [/B] Consider two charged particles 1 and 2, each of them able to translate (move from place to place) and to spin.Homework Equations I can not completely think of relevant equations at the moment. The Attempt at a Solution [/B] I am a bit confused on how charged particles...
  5. Z

    B Clarification Requested: Particles as higher dimensional objects

    I request clarification on the the dimensional definition of fundamental particles. 4th dimensional objects interacting with the 3rd dimension would appear as coherent 3D slices of their 4th dimensional bodies at time T. The "slice" observed would be unknown without complete knowledge of the...
  6. M

    I Dark Matter Particles: College Student Seeking Theorem Evidence

    I am in college and trying to develop a theorem, If there is any information there is any papers or evidence to dark matter being particles could you please tell me as it will do me a great favor. Thank you for reading
  7. smodak

    Quantum Relativity, Elementary Particles and Black Holes

    Relativity, Elementary Particles and Black Holes by Thorne & 't Hooft Any idea what this book is and why it is unavailable? Is it a popular science book? I did not know that Thorne and 't Hooft co-authored a book.
  8. S

    Potential Energy vs. Position Graphs

    Homework Statement A particle has the potential energy shown in the figure. (Figure 1) What is the x-component of the force on the particle at x =5, 15, 25, and 35 cm? I'm stuck on finding the Fx at 25 & 35 cm.Homework Equations F = -du/dx 100 N = 1J/cm The Attempt at a Solution Slope...
  9. C

    Can three particles be entangled?

    Homework Statement I'm trying to understand the information paradox at a black hole. Can three particles be entangled? I read on a site that it's impossible to entangle multiple particles. When searching on google I found out that it is possible for multiple particles to entangle. So what...
  10. F

    B Does right/left spin reverse in tunneling particles?

    As I understand it, a relativistic reversal can occur in a Lorentz boost. A particle's forward angular momentum can become backward angular momentum, if the observer accelerates sufficiently. But the particle and its angular momentum are unchanged. The only change is in the observer’s frame...
  11. DjMadness

    Magnets -- Experiments with sheets and particles

    Hello I have magnetic sheets A4 sized that could be bent but not enrolled, having a thin thickness. I want to cut them in a circular shapes. The idea, is there any possibility to make one of them (or other material same physics) positively charged and second negatively charged; then have...
  12. L

    Voltage derivation for charged particles

    I have a very weak understanding of the particle modelling of electrical phenomena.1: Electric field =\frac{Force}{Magnitude of charge} 1 is The definition of electric field on a particle (?) 2: Force = \frac{Q1*Q2*K}{R^2}\\ 2 is Coulombs law, to find force between two particles. 3...
  13. F

    Decay of a particle of mass M into two particles

    Homework Statement A particle of mass M and 4-moment P decays into two particles of masses m1 and m2 1) Find the total energy of each particle (lab frame). 2) Show that the kinetic energy T1 of the first particle in the same reference frame is given by $$T_1= \Delta M (1 - \frac{m_1}{M} -...
  14. F

    I Two particles: Entangled State vs Non interacting State

    Hello Forum, Could anyone offer some insight on this topic? In the case of a physical system composed of multiple particles, there is only one single wavefunction that depends on the three position variables of each particle and the parameter time t. For example, in the case of 2 particles, we...
  15. P

    Inelastic collision between two perpendicular particles

    Homework Statement A particle of mass m1 collides with a particle of mass m2 initially moving at right angles to it(see Figure 1 below). Calculate the final velocities of each particle, and the angles at which the particles leave the collision site( as measured with respect to the original...
  16. tomdodd4598

    I Interpreting These '2 Particles in a Box' Plots

    Hey there, I am familiar with the mathematics of multi-particle systems, but have now moved on to trying to plot them. I was a little ambitious and thought I'd attempt to somehow plot energy eigenfunctions of two particles in a 2-D box. Obviously I immediately ran into the issue that there are...
  17. Algr

    Alternative particles in Nucleus?

    Tony Stark: I've tried every element. Nick Furry: You haven't tried all of them. Are there any other particles besides protons and neutrons (and their antis) that could be stable in the nucleus of an atom?
  18. D

    B Do particles actually have a volume?

    You often hear "most of everything is made up of empty space", referring to the idea that atoms only have mass in their nucleus. It seems to me that this is trying to explain physics in terms of everyday intuition, rather than the other way around. Specifically we have this intuitive notion of...
  19. L

    Coulomb's Law problem: Charged particles and the net electric field and force

    Homework Statement Figure (a) shows charged particles 1 and 2 that are fixed in place on an x axis. Particle 1 has a charge with a magnitude of |q1| = 19e. Particle 3 of charge q3 = +16e is initially on the x axis near particle 2.Then particle 3 is gradually moved in the positive direction of...
  20. J

    Calculating electrostatic force on particles

    Homework Statement Homework Equations F=(kq1q2)/d^2 The Attempt at a Solution So it should be fairly easy to use "parts" to come up with each answer Part a Because particle 1 has no pull in the x direction I should be able to ignore it when finding the x component of the force...
  21. M

    I Virtual Particles: Speed & Impact on Rocket

    Hi, quantum fluctuations enable virtual particles in space. If a rocket travels through space, these particles (real ones of antiparticle-particle pairs) could impact it. Is the effect of an impact dependent of relative speed of such particle and the rocket? For example rocket could be warmed...
  22. J

    Harmonic oscillator with 3 charged particles

    Homework Statement I got an alpha particle (charge 2+) fixed at x=0 and an electron fixed at x=2. I then add a fluor ion (charge 1-) to the right of the electron and we note his position xeq. The question is to find the constant spring (k) relative to the harmonic oscillation made by the fluor...
  23. Brunolem33

    B Uniformity of Particles Formed After Big Bang

    In the beginning there was the Big Bang...then there was plasma...then there were particles, and so on... Now, how is it possible that from a cooling plasma, randomly (?) emerged particles that are so perfectly uniform? I mean, all neutrons are exactly the same...size, mass, properties...and...
  24. G

    I Gibbs paradox for a small numbers of particles

    Hi. Trying to solve the Gibbs paradox for two identical volumes of ideal gas with ##N## particles each, I found the mixing entropy to be $$\Delta S=2N \log(2)-\log((2N)!)+2\log(N!)\enspace .$$ The usual approach now uses Stirling's approximation to the order ##\log (n!)\approx n\log (n)-n##...
  25. phosgene

    Time taken for two relativistic particles to meet

    Homework Statement A particle P undergoes the hyperbolic motion x_{P}(t) = \frac{c}{a}(c^2 + a^2 t^2)^\frac{1}{2} along the x-axis of frame S, where c is the speed of light and a is a constant. A second particle, Q, undergoes the motion x_{Q}(t) = \frac{1}{2}ct + \frac{c^2}{a} and so...
  26. gabi123

    I Can Antiparticles Collide with Each Other and Create Energy?

    Now it is common knowledge that antiparticles destroy particles on collision, and release the same amount of energy as if the masses of the two particles were combined and plugged into E=mc^2. But what about an antiparticle colliding with another antiparticle? Would they have the same effect on...
  27. M

    I Energy associated with entangled particles

    Assuming two particles are entangled, is there a quantifiable energy associated with separation distance? Rephrasing the question: If two entangled particles are distance x1 apart and another pair of identical entangled particles are distance x2 apart, is there a difference in the energy...
  28. M

    MHB Proving |PR|=3|RQ|: Two Particles Collide

    a particle is projected vertically upwards from a point P. at the same instant a second particle is let fall from rest vertically at q. q is directly above p. the 2 particles collide at a point r after t seconds . when the 2 particles collide they are traveling at equal speeds. prove that...
  29. physea

    A What are the available methods to separate particles

    Hello! What are the available technologies to separate small particles from a flow of gas? I assume that if the particles are magnetic we can apply a magnetic field? Any other methods? And what if they're not magnetic? Thanks!
  30. R

    Gravitational potential between two massive particles....

    If my understanding is correct, all particles are sources of gravitational fields (albeit minor ones), and the gravitational potential energy between two bodies is given by: U = -GMm/r So, if we have two Z bosons (or any other bosons with mass but no repulsion due to charge) which are traveling...
  31. V

    Two particles undergoing circular motion

    Homework Statement Homework EquationsThe Attempt at a Solution I am actually stumped by this seemingly simple problem . Since both the particles are moving , in order to calculate angular velocity of Q with respect to P looks to be difficult as the relative velocity of Q w.r.t P is...
  32. M

    MHB Are These Equations for Particle and Wedge Dynamics Correct?

    im stuck on question 8. the equation i got for the wedge is .6R -.5S=ma r stands for relative force of the particle s stands for relative force of the wedge . i got the equation 4mg-R=5m(.6a) for the particle where a stands for acceleration of the wedge. does anyone know where to go from here...
  33. Vibin Narayanan

    B Gauge Boson Exchange: Do Particles Influence Each Other?

    Do a particle influence another particle by exchange of gauge bosons? If so, how?
  34. P

    Can massless particles reach the boundary at z=0?

    Homework Statement We're working in 2-d Anti-de Sitter space with metric: \begin{eqnarray*}ds^2 = \frac{1}{z^2}(-dt^2 + dz^2)\end{eqnarray*} with 0<=z. The solution is: \begin{eqnarray*}z^2 = (t+c)^2 + B\end{eqnarray*} And we've been asked to plot this (I think its a parabola with minima at...
  35. C

    A Fullerene confined metal particles and increasing pressure

    Hello, I would like to ask a question regarding possible change of orbital conformation of a fullerene particle filled with metal. Is there any basis to the assumption that for if you encase a metal, such as a round nanoparticle of lead cooled to minimal thermodynamical state, just so it fits...
  36. D

    I Virtual Particles and Charge Screening

    The following article says virtual particles don't exist or are just book keeping device. https://www.physicsforums.com/insights/physics-virtual-particles If that's the case, then how do you explain charge screening? We observe the charge of an electron to be less than the bare charge, or what...
  37. Allen_Wolf

    B Acceleration of Particles: Black Holes & Speed of Light

    I have a little doubt to get cleared. Gravity of the Earth causes an acceleration of 9.8 m/s2 which increases the velocity of a body at free fall. So for a very massive body like a black hole FOR INSTANCE, the acceleration due to gravity on a body will be very high, right? So if a body falls...
  38. M

    MHB Particles on a Wedge Q4: Find Accel & Force

    Q4 A wedge of mass 11 kg is held on the ground with its base horizontal and smooth faces inclined at 30° and 45° respectively to the horizontal. A 5 kg mass on the face inclined at 30° is connected to a 7 kg mass on the other face by a light inextensible string which passes over a smooth light...
  39. pittsburghjoe

    I Can particles exist without duality?

    Does Duality serve any other purpose than preventing investigators from fully understanding the framework of our reality?
  40. T

    Difference in Radius of Charged Particles in Magnetic Field

    Homework Statement Ions having equal charges but masses of M and 2M experience a constant electric field while they travel a fixed distance d and then enter a uniform magnetic field perpendicular to their path. If the heavier ions follow a circular arc of radius R, what is the radius of the arc...
  41. petrushkagoogol

    Behavior of charged particles in Free and Bound states

    If there are 3 positive charges of +1, +3, +5 coulombs equidistant from a negative charge of 1 coulomb what positive charge will this negative charge be attracted to ? Is the result different if the charges exist in a “bound” state (resulting in electrovalent compounds) where a positive charge...
  42. M

    B How long can a virtual particles exist in a vacuum state?

    As much as I have understood, virtual particles keep appearing and disappearing in a vacuum state. This leads to zero-point energy, Casimir effect etc. Now, I want to know if there is a lifetime (i.e. a time limit) for which these virtual particles can exist before disappearing. Also can there...
  43. petrushkagoogol

    I Compute Relativistic Velocities of Photons & Neutrinos

    Can we compute the relativistic velocities of 2 photons or 2 neutrinos ? :))
  44. J

    Fixing Error: 10 Particles Got Lost in Fast Reactor Model

    Hi I am trying to run a fast reactor model but I cannot figure out what is happening because I get the error: run terminated because 10 particles got lost. I am using the sdef card (with and without parameters) and the model is not running. Hope you can help me to fix any mistake I did. The...
  45. Hallucinogen

    B Which fundamental properties of particles can actually vary?

    Hi everyone. Very orderly forum you have here. I'd like to ask a few philosophical questions which are very fundamental to QM. Firstly I assume we all agree that a fundamental particle - imagine an electron or quark - has multiple inherent properties which are all separable from each other, such...
  46. I

    Temperature inside a box as particles escape a small hole

    Homework Statement Edit: Thanks to gneill for showing me the LaTeX ropes. Equations should work now. A perfect gas enclosed within a container escapes into vacuum through a small circular hole. The particle flux through the hole is ##\frac{nc}{4}## and the energy per particle escaping can be...
  47. Tommyboyblitz

    B Particles touching each other inside a Black Hole's core....

    I had a quick question regarding particles touching each other. I know no one can really say for sure but inside a black hole where the gravity is astronomical would the particles be considered to be pressed up against each other? are the forces involved enough to compress atoms down into the...
  48. Elvis 123456789

    System of particles with non-degenerate energy levels

    Homework Statement A system has three non-degenerate energy levels with energies 0, ε, and 2ε. a) Calculate the entropy of the system if the three levels are populated by two distinguishable particles such that the total energy is U=2ε. b) Calculate the entropy of the system if the three...
  49. quantumfunction

    B Do we measure the particle or the wavefunction?

    It seems to me that we don't measure a particle because a particle doesn't have an objective existence independent of the wave function or does it? The wave function in this case would have to be real because you can't have probability without the underlying possibility of a specific outcome...
  50. J

    B Relativistic Simulation of Charged Particles: How a Physicist Would Go About It

    Supposed i wanted to do a relativistic simulation of charged point particles moving at different velocities and interacting with each other. My simulation would give me the x,y,z coordinates of each particle seen from an arbitrary observer's point of view, at a given t. The t given however, is...
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