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. S

    Three particles, finding Q of one of them (Coulomb's Law)

    Homework Statement "A particle with charge -3.03 nC is at the origin, and a particle with negative charge of magnitude Q is at x = 49.0 cm. A third particle with a positive charge is in equilibrium at x = 20.8 cm. What is Q?" Homework Equations I'm fairly certain that Coulomb's Law is the...
  2. J

    Maximizing Displacements in SHM: Is ωt = -Φ/2 the Correct Value?

    Homework Statement Homework EquationsThe Attempt at a Solution The displacements of the two particles are given as y1 = Asin(ωt) y2 = Asin(ωt+Φ) y2 - y1 = Asin(ωt+Φ) -Asin(ωt) y2 - y1 = 2Acos[(2ωt+Φ)/2]sin(Φ/2) Maximum value of displacements between particles is given as 3A/2 . This...
  3. G

    Momentum of alpha particles

    Homework Statement Fast moving α particles of mass m make collisions in a cloud chamber with gas atoms of mass M and negligible initial velocity. After a collision, the velocities of the scattered α particles and the recoiling gas atoms are v and V respectively, the former being inclined at an...
  4. kq6up

    I P and X completely describing a system of particles

    I have heard it said that in classical physics that if one knows all the particles of a systems momentums and positions, that the evolution of the system can be completely known. I would imagine this also would have to include the nature of all the forces acting on the particle. Also, for...
  5. Souhardya Nandi

    I Exploring the Distinction Between Virtual and Real Particles in String Theory

    I am reading a bit about them. However, I feel that there is not much difference between them except for the life span. Can you please help me understand the distinction ? Can this be explained on basis of string theory ? Please elaborate.
  6. P

    I Measuring particles through experiments

    How is it reliably ascertained that the "particles" 'measured' can be "proven" to have "traversed the experiment" and are not just conveniently (or inconveniently depending on perspective) incident / external? Is this obtained through statistical analysis from a large number of repetitions...
  7. LeInvertedPenguine

    I How elementary particles form matter

    Hello, So i wonder how elementary particles which are said to have no physical extension on a larger scale are able to form what is known to us as matter? Aka stuff with an observable physical extension.
  8. D

    B What particle(s) pass through Earth?

    What particles(s) can pass through hundreds of miles of the Earth? Is it only neutrinos, or is there some other particle(s)?
  9. F

    Two particles moving in a central potential

    Homework Statement Two particles move in a central potential. The potential has the form V(r1, r2)=-a/(/r1-r2/^1.5)... Homework EquationsThe Attempt at a Solution I am having trouble understanding what it means for two particles to move in a central potential. From what I understand a central...
  10. C

    I What causes disturbance on my phone camera?

    Hi I have a cheap smart phone with a low quality camera when I go to take a picture there is what I would describe as like old television static appearing in front of the image as it appears on the phone screen (although what is beyond it can still be seen). I am wondering if this is just dust...
  11. ISamson

    B Light, Photons, Waves, Particles: Wave-Particle Duality....

    Me and my friend have recently (half a year ago) had a huge debate, between ourselves, about the wave-particle duality. We took sides in light being a particle or a wave. I was for particle he was for waves. At the end of a hot-filled week of arguing, the debate ended up with the acceptance of...
  12. Mcbleak

    B Expanding space time and Virtual particles

    If space time (the universe) is infinitely expanding what happens when it rips? Have we observed Virtual particles in an area and counted them? Does the expansion of space time affect the amount of Virtual particles in a particular area? Is it theoretically possible to expand space time to a...
  13. VSayantan

    Entropy of a System of Spin-half Non-interacting Particles

    Homework Statement A system having ##N## non-degenerate energy eigenstates populated by##N## identical spin-zero particles and ##2N## identical spin-half particles. There are no interaction between any of these particles. If ##N=1000## what is the entropy of the system? Homework Equations...
  14. C

    Collision of two charged particles projeced in magnetic field

    Homework Statement Two particles having mass m separated by a distance d is uniform magnetic field as shown in the figure . If v=qBd/m, at what instant does collision occur. The coulomb force between the particles is switched off. Homework Equations T=2πm/qB The Attempt at a Solution For the...
  15. A

    A String Vacua and Particle Interactions

    I've been doing a little bit of reading on string theory, and the very large number of string vacua that are possible (i.e., perhaps 10^500 or more). One thing that is not clear to me is exactly what constitutes a 'vacuum' in string theory. In QFT theory, the vacuum is defined as the state with...
  16. Fraser MacDonald

    What is the electrostatic force field?

    I have just covered the electricity unit in my advanced higher physics course, and have happily accepted that a force is created between charged particles. I understand that coulombs law can be used to calculate this force, but here is my question. What actually is this force between the charged...
  17. robindymer

    B How does vibration affect the Higgs field interaction?

    I have been thinking about the Higgs field and how things interacts with it. I thought about why photons for example does not interact with it while quarks does. It could be because of the size and if when a particle is a certain size it will interact with the Higgs bosons and then slow down and...
  18. K

    I Exploring Mass & Constrained Massless Particles

    Poorly phrased but here goes - I'm trying to understand some of the SpaceTime videos on youtube, specifically the massless mirrored box and how the mass (ie resistance to acceleration) is a function of the change in momentum of the contained (constrained) photons. It makes sense but raises a...
  19. Pushoam

    No. of spinless particles in the left half of a box

    Homework Statement How to solve question no. 35? Homework EquationsThe Attempt at a Solution Since the particle is spinless, spin = 0 , this means that the particle is a boson. Applying Bose - Einstein distribution function, ## f(E) = \frac1 { e^{\beta ( E - \mu)} -1}## I can get the value of...
  20. F

    I Does the path Integral contain virtual particles?

    So Feynman's path integral considers every possible path that a particle could take from start to end. In that process, there would be a path which contains a segment from, say, A to B at time t. But there could also be a path with a segment from B to A at that same time, t. If so, would this...
  21. AlexanderinCbus

    Question from a layperson: Particles & temperature

    Hello! First post here so go easy on me. I am a Physics enthusiast, but I fear I am a layperson when it comes to the field. Most of what I know comes from low level college classes and the youtube channel PBS Spacetime. I have a question that might be a ridiculous one. But here goes. (Go easy...
  22. C

    Collision Angle for Two Particles with Constant Velocity and Acceleration

    Homework Statement I am currently solving a problem and I am not sure if it is correct. There are two particles A and B. A has a constant velocity with |\vec{v}| = 3 and starts from y = 30 B has constant acceleration with |\vec{a}| = 0,4 The goal is to find the angle between the...
  23. R

    B Possible Loophole in the uncertainty principle

    The uncertainty principle states that anyone given person who knows a lot about a given particles velocity will know less about the location, but if then they try to observe the location, the less they will know about the velocity. What if two scientists observed one particle though. One...
  24. ISamson

    B How do particles become entangled?

    Hi. I know that particles can become entangled, but I don't understand the actual physical process that the particles are involved into become entangled. Can anyone help me? Thanks.
  25. S

    B Exploring the Existence and Energy of Virtual Particles in Quantum Mechanics

    Hello everyone, I am here today with a doubt, I first apologize for my ignorance on the subject, but come on, the uncertainty principle predicts that in the "vacuum" there are virtual particle that cancels out constantly, but my question is: which is the amount of energy that exists in this...
  26. S

    B Electromagnetic fields of fundamental particles -- help please

    Hi, we know that the particles have intrinsic properties for them electric field and magnetic moment, but for what I mean particles, I mean quarks, the fundamental blocks of (protons, neutrons and mesons) with everything that nobody explained as electric and The magnetic field of a particle and...
  27. Nathan Warford

    B What are the predicted sizes of elementary particles?

    I understand that the Standard Model of QFT treats elementary particles like the electron, quark, photon, muon, etc. as point-like objects. But I've also heard that a "point-like particle" is nothing more than an idealization of a particle. Elementary particles can be treated as point-like...
  28. I

    Struggling with constrained motion of connected particles

    Hi everyone! Really struggling with this question here, was hoping someone could point me in the right direction? https://puu.sh/xVitw/4c0b89c576.png 1. Homework Statement Set origin to bottom right. OA is y (Which using cos(60)*R you can determine to be 0.5R). OB is x (which you can...
  29. R

    Electric potential due to collection of charged particles

    Homework Statement A particle with charge q1 = -6.75x10^-6 is located at (0,3.25x10^-2 m ) and a second particle with charge 3.2x10^-6 is located at (0,-2.75x10^-2 m) what is the electric potential due to the two charges at the origin? Homework Equations V = kq/r The Attempt at a Solution So...
  30. C

    System of two particles: Prove motion along connecting line

    Homework Statement Given an isolated system of 2 particles in space, we can express the motion of both particles as follows: $$m_1\ddot{\vec{x_1}}=-\frac\partial{\partial \vec{x_{1}}} V(\vec{x_1},\vec{x_2})\\ m_2\ddot{\vec{x_2}}=-\frac\partial{\partial \vec{x_2}} V(\vec{x_1},\vec{x_2}),$$ where...
  31. W

    I Questions Regarding Free Particles - Griffith's QM (I)

    Homework Statement [/B] 1) I don't quite understand what 2.94 means on its own. It was derived from 2.93, yet it doesn't show a superposition of any sort. The author then takes 2.94, and attempts to normalise it by stating ##\int \Psi_k^* \Psi_k dx = \mid A^2 \mid\int dx = \infty ## What...
  32. E

    Two particles on a vertical ring

    Homework Statement In this problem, I have two particles that slide on a ring with a radius of R. The ring is orientated in a vertical plane. One of the particle is heavier than the other and has a mass of 3m. The heavier particle is attached to a spring with an unstrectched length of 0 and a...
  33. C

    B What is the Physics behind Smells?

    I was thinking about light and sound and then I thought "what about smells?". What I mean is, what's the physics behind a smell?? Is it a wave, is there particles that you smell?? It sounds weird but I'm really curious about this. I understand it might be in the biology sort-of area but then...
  34. D

    B Superposition particles in a box

    If I had a box with a bunch of particles in superpositions in it, what would I find if I found the mass of the box? First: Is it possible to have have box like this? If not what about theoretically. Second: Does weighing the box collapse the superposition of the particles? Third: Could I, by...
  35. O

    Distance of two moving particles

    Homework Statement There are two particles. There are moving equally on two intersecting lines to intersection. On time t=0 is the distance of two particles d. The velocity of one particle relative to the other has a projection u in the direcion of d. In direction perpendicular to d is the...
  36. S

    A How do we know the spins of elementary particles?

    How do we know the spin of an elementary particle? For example, a fermion has spin 1/2; a photon has spin 1; and even the ficticious graviton has spin 2. How do we know these spins? In other words, how are these spins determined?
  37. A

    A Observable particles as asymptotic states....

    I've read Arnold Neumaier's excellent Insight article on virtual particles, but I'm very confused about one thing: Observable particles are considered to be on-shell, and as 'asymptotic states' at time +- infinity. Now, in a scattering experiment, I may produce a new particle, which will travel...
  38. P

    B The Problem with Point Particles

    There is a clear problem with the continuing belief that (any) point particles exist in nature. Quantum mechanics, relativity and even classical physics all forbids this approach. Let's explore why: 1). Quantum theory forbids point particles, because points themselves do not make sense in phase...
  39. B

    I Probability of creation of virtual particles

    Is it correct to assume that all known particles may be created as virtual particles in the vacuum? If so, is there a higher probability of a particular particle being produced than say some other particle type. For example, is an electron more likely to be created as a virtual particle than a...
  40. A

    B No new fundamental particles at CERN until today

    I remember reading in some book, that the most important experiments are those that produce negative results: the Michelson-Morley experiment for example. The standard model is complete after the Higgs boson. I believe that if no new particle appears in CERN, it would be one of the greatest...
  41. bbbl67

    I Particles of matter as Bosons?

    Now from my basic understanding of particle physics, matter is supposed to be fermions, while particles involved in force interactions are bosons (photons, gluons, W/Z, and Higgs). Now, apparently there are also some composite particles of matter that are considered to be bosons too. For...
  42. C

    Motion of Charged Particles in Electric Fields

    Homework Statement This is the question: An electron at rest of mass 9.11 × 10−31 kg is accelerated through a potential difference of 350 V. It then enters some deflecting plates of 50 V with dimensions as shown. Calculate the distance x (deflection of the electron) (Charge on an electron is...
  43. Pushoam

    Work Energy Theorem: particle, system of particles, rigid body

    Question: A) Derive the work - energy theorem for one particle. B) Check whether it is applicable for a system of particles and a rigid bodyWork - energy theorem for one particle system, total sum of work done by individual forces = work done by total force To show the above equality, let's...
  44. yrjosmiel

    The acceleration of two colliding particles

    Something about collisions has been bothering me. Let's say I have 2 particles with equal mass: one is moving at velocity v towards the other particle. Kinetic energy and momentum is conserved during this collision. However, I have a question: what is the acceleration of the particles during the...
  45. Suppaman

    B Cosmic Rain: Exploring the Mysteries of High-Energy Particles

    I was just reading the article about “cosmic rain” here and they talk about these very high energy particles striking a detector. But as I understand things, these have to be waves, not particles, put up a double slit and these things will go through both as waves (and since they do not know...
  46. Auto-Didact

    A Erebons: Planck mass Dark Matter particles

    Erebon theory is a novel explanation of dark matter recently invented by Roger Penrose. Erebons are scalar particles of the order of a Planck mass which can only interact gravitationally. When erebons decay, they release their energy as oscillating classical gravitational waves on the order of...
  47. C

    B Heisenberg applied to accelerated particles

    I may be getting these Thread Levels wrong. I get the impression that they apply to my level of knowledge such that someone else might be able to give an answer that I might be able to understand rather than the level of knowledge required to answer the question. Rest assured I am quite stupid...
  48. T

    B Understanding Quantum Entanglement: Debunking Common Misconceptions

    I have some questions about quantum entanglement 1 - Why is this phenomenon considered so surprising, if it just states conservation of quantities (e.g. spin, momentum) and we are already accostumed with conservation of quantities in classical physics 2 - Suppose we have, say, a hydrogen...
  49. C

    Two particles' spin Hamiltonian

    Homework Statement Hi, I'm trying to familiarize with the bra-ket notation and quantum mechanics. I have to find the hamiltonian's eigenvalues and eigenstates. ##H=(S_{1z}+S_{2z})+S_{1x}S_{2x}## Homework Equations ##S_{z} \vert+\rangle =\hbar/2\vert+\rangle## ##S_{z}\vert-\rangle...
  50. davidge

    I Spin 0 Particles & General Relativity | Carrolls Notes

    In Carrolls notes on General Relativity, it is said that the general formula for finding the spin number of a particle is $$\frac{360°}{\theta}$$ where ##\theta## is the angle of rotation, after which the state of the field describing the particle returns to its original state polarization. He...
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