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. LuckyFox

    B Strange cosmic particles in my detector

    Hello! This is my first post on this forum. I am writing because I would be very interested to know the opinion of the forum participants on this issue. Almost ten years ago, I wrote a program Cosmic Ray Finder to record particle traces on a webcam (analogue of the project DECO) (the webcam is...
  2. O

    MCNP Help: 10 Particles Lost

    In my intro class, I am trying to design for radiation sources. Currently, I am trying to plot the flux from neutron and photon source locations progressively moving further and further away, however the code is not running and it says "geometry error: no cell found run terminated because 10...
  3. stephen193

    I like listening when nature speaks, on its own terms.

    I am nobody important, and don't have any relevant training. I do what I enjoy, and learn whatever my curiosity demands. Lately, that has involved taking a close look at the properties of fundamental particles, trying to see if I can identify any interesting patterns. There are a few! I hope to...
  4. mister i

    B Percentage of known energy in the Universe

    It is said that the universe is made up of approximately 4.9% ordinary matter, 26.8% dark matter and 69.3% dark energy. Why isn't ordinary energy included in this "pie"? I suppose it is included within ordinary matter, but could it be calculated what % are particles with mass and what % is pure...
  5. MatinSAR

    Statistical mechanics: particles in magnetic fields

    Let’s consider that the total energy of this system is represented as ##E=-2mB##. Question 1: how many microstates correspond to this energy level? We have ##2^4=16## microstates. ++++ Total magnetic moment: ##4m## Energy: ##-4mB## - - - - Total magnetic moment: ##-4m## Energy: ##4mB##...
  6. Gullets

    A Are Symposium Books as Comprehensive for Particle Physics History?

    Books like Griffith, Martin, and Perkins are best if I consider them for the thorough history of particle physics.
  7. S

    Collison between two particles

    I am stuck with this problem. Intuition tells me the answer is no, but I am struggling to prove it. If we consider two particles travelling in the same direction, the 2nd particle will gain velocity (impulse is in same direction to velocity), and the first particle will lose velocity (if it...
  8. T

    I What makes up the bare mass of elementary particles?

    And as an aside what is the difference between bare mass and invariant mass of such particles?
  9. R

    A Why don't we see super-symmetric particles?

    we can se many particles, also we can detect and produce antimatter however my question is why even at high energies we can not see any supersymmetric partner of a particle ?
  10. Pixelex

    B Quantum Entanglement in Practice

    How is quantum entanglement done in practice for different particles with different properties eg. spin, polarization, etc.? Why is entanglement useful for quantum circuits? *I am curious about how they are actually entangled and used. I don't know how is entanglement applied in practice so I...
  11. Ggb

    B Coulumb's Law at 1 light year distance

    Hi, What happens to the force when the particle are kept at 1 light year distance. I agree practically the force would be very weak because of inverse square law, theoretically what happens to the force?
  12. Pushoam

    B Scattering of light by dust particles

    Inside a dark room, when light comes through a hole, we see the dust particles as the particles scatter the light. But, when the whole window is open, we don't see the dust particles scattering the light. Why?
  13. S

    MCNP: How to display particles outside the source?

    Particle display in visual editor of mcnp input file only shows particles inside source, I am interested to see particle path towards tally region. Plz guide thanks
  14. S

    B Sun's Mass Loss: 4 Billion kg/sec from Sunlight & Ejected Particles

    Found out the sun loses 4 billion kg per second worth of sunlight in e = mc². How much mass does the sun lose per second if we include all particles that the sun ejects such as ions and neutrinos? (and, neutrons?)
  15. AngryBeavers

    Focus all of your ire on me, if you would

    TL;DR Summary: A completely non-scientific look at wave function, because ChatGPT persuaded me to include my thoughts somehow, some way. Howdy, the post title, as im sure you've noticed, is a weird one, and out of place in such a location. Fitting, considering the topic, I think. Backstory...
  16. harryharns

    C/C++ Perform RK4 between 2 Clusters in Magnetic Field

    I have a simulated data of charged particles in a magnetic field. I have selected clusters, each cluster contains a set of points(x,z) and I want to perform RK4 between the first and second clusters and fill the positions in a histogram. I have selected the clusters with the initial...
  17. mgcgian

    I Photoelectric effect: Saturation voltage

    Hi, I just got two inquiries: My understanding is that the saturation current is reached when the intensity of light is fixed, when the potential difference is at its positive maximum magnitude. Subsequently, whatever kinetic energy store of any photoelectrons, however deep within the metal's...
  18. emilmammadzada

    Particles produced and energies in the target Geant4

    Dear experts.Which example file in Geant4 can I use to find the particles and energies produced in the target?
  19. Pradyuman

    A How can gauge fields be associated with real particles?

    When we make our lagrangian invariant by U(1) symmetry we employ the fact that nature doesn't care how I describe it, but, how come that I can associate the real physical particles with the coordinates I use to describe? Even though gauge symmetry is not a physical Symmetry,
  20. P

    A system of independent particles (energy levels)

    Hi guys, Can you give me some feedback on whether my calculation is correct? I applied the formula below (Boltzmann Distribution) but I didn‘t know what to use for the variable z. I don‘t even know if I used the correct equation. Can you help me further? The task is: Consider a system of...
  21. Ranku

    I Correlation between size and mass of particles

    Is there a correlation between the size of a matter particle (defined as its matter wavelength) and the mass of the particle? With the photon, its wavelength and its energy/mass are inversely correlated. Is it also true of matter particles?
  22. milkism

    Conservation of relativistic energy, collision of particles

    Question: With maximum do they mean that the speed of the pions is the same as the proton and an antiproton? Otherwise there will be two unknowns, and if I use both relativistic-energy and momentum conservation equations I get difficult equations.
  23. D

    B Subatomic particles and dark matter

    I am by no means an expert in physics, but I have a question. We have recently found the particle that cause attraction (Bos-Higgs) would it not be reasonable to think the there is a particle that cause repulsion? That would lead to cluster of attraction surrounded by fields of expansion. Would...
  24. N

    B Exploring the Intersection of Oscillations/Waves & Particles in EM Fields

    For an upcoming presentation I am looking for a topic which covers both the field of oscillations/waves and particles in electromagnetic fields. Do you have any interesting ideas for a possible topic? Many thanks for your help in advance!
  25. Suryabarta Saha

    I Exploring Microscopic Particles: Interactions & Measurement

    1.How is that possible for us to say that a non-interacting microscopic particle can have numerous values of a physical parameter in a given instant? the mixed state of a microscopic particle is simply the probability distribution of the particle having those values of a given physical parameter...
  26. Like Tony Stark

    Collision between two particles with different spin

    1) The Hilbert space for each particle and the system are: ##H_1={\ket{\frac{1}{2} \frac{1}{2}}; \ket{\frac{1}{2} -\frac{1}{2}}}## ##H_2={\ket{1 1}; \ket{1 0}; \ket{1 -1}}## ##H=H_1 \otimes H_2## 2) I'm not sure what "considering the total Hamiltonian" means, but I think that the two CSCO...
  27. Addez123

    Determine the particles most probable position

    To get expected value I use $$E = \int \Psi^* Q \Psi dx$$ where Q = x $$4a^3 \int xe^{ax} \cdot x \cdot xe^{-ax} dx = 4a^3 \int_0^{\inf} x^3 dx$$ which is undefined. But the answer is suppose to be 1/a.
  28. C

    Finding ##v## for four particles after being released from square

    I tried solving the problem above by using conservation of energy ##U_{Ei} = U_{Ef} + KE ## ##\frac{4k_eq^2}{\sqrt{2}L} = \frac{4k_eq^2}{2\sqrt{2}L} + 4(\frac{mv^2}{2}) ## ##\frac{2k_eq^2}{\sqrt{2}L} = 2mv^2 ## ## v = \sqrt {\frac {k_eq^2}{\sqrt{2}Lm}} ## However, the solutions solved the...
  29. Vilius

    GM counter and alpha particles

    Hi, I am an undergraduate electronics engineer building a GM counter for my final assessment. I read a lot of theory about GM counters as well as the nuclear physics theories in general, but there is one thing I can not find an answer to. Why do none of the GM counters detect alpha particles? I...
  30. sal1854

    I Direction of motion of particles with total spin under magnetic field

    According to Chapter 8 of Griffiths' book Introduction to Electrodynamics, the magnetization force that acts on a magnetic dipole is $$F_M=\nabla (m \cdot B)$$, where ##m## is the magnetic moment and ##B## is the magnetic field. For a paramagnetic or diamagnetic particle...
  31. J

    I Three Plus Anti-symmetric Particles

    So I understand that fermions are anti-symmetric under exchange, but in the contexts I've seen this explained they were always talking about two particles, or at least two wavefunctions. I'm curious how this works when there are three or more particles. Is any two given pairs of those 3+...
  32. emilmammadzada

    Particles transporting in MCNP5

    Is it possible to transport only photon , electron and neutron in mcnp5?
  33. J

    I Quantum fluctuations & 'virtual particles'

    I've been reading about how language around virtual particle fluctuations is metaphorical. This is helpful: https://www.physicsforums.com/insights/vacuum-fluctuation-myth/ I'm just trying to understand a bit more from a layman's point of view. I found Matt Strassler's article 'Virtual...
  34. Spector989

    System of particles, impulse and conservation of angular momentum

    So i was able to solve the angular velocity part but i don't know how to find the velocity of centre of mass . For the first part i simply conserved momentum about COM because if i consider the particles as a part of the same system as rod the collision are internal forces . I am mainly...
  35. B

    Two Particles Connected by Massless Rod: Dynamics Analysis

    Two point-like particles of mass m. The particles are rigidly connected to each other with a mass-less rod of length L. The particles are initially at rest in such a way that one particle is at the origin and the other is at the point (0, L). A point-like particle of mass M collides with a...
  36. A

    I Some classical models of particles and quantum gauge theories

    My article has been published in Quantum Reports. Expanded abstract: There is currently no consensus on the interpretation of quantum theory, so this article may be of interest as it contains a review and new results on some relevant mathematical models emulating well-known quantum theories...
  37. BadgerBadger92

    B How do particles get their spin?

    https://physics.stackexchange.com/questions/418865/why-does-an-electron-have-spin I’ve been trying to do research on this and haven’t gotten a clear answer. It sounds like they get it through particle interactions, but I may be misreading it. Is there an answer to this? And if there is, how...
  38. C

    I Resources to learn about particles on a grid/mesh

    Hello. I am looking to learn about averaging out a particle gas or any other type of organization of particles within a system or volume that can be approximated onto a grid or mesh where the particles are at a constant distance from each other: https://en.wikipedia.org/wiki/Particle_mesh. I...
  39. D

    Dissolving Particles in Oil (but Water resistant)

    Hello Everybody, I have a superoleophobic surfaces which shows high contact angle for Water, Oil, Hexadecane... I am looking for a kind of particles which are attached to the surface and once I touch them with a droplet of oil are dissolving in that oil droplet. If I then remove the droplet...
  40. S

    I Brownian motion of charged particles?

    If we have charged particles having Brownian motion, would this motion be associated with (or produce) heat or electricity? Would it produce electromagnetic radiation (and if it would produce it, what type of radiation in the electromagnetic spectrum)? Could there be Brownian motion of charged...
  41. DrClaude

    B Sabine Hossenfelder on the search for new particles

    https://www.theguardian.com/commentisfree/2022/sep/26/physics-particles-physicists Note: Please read what she is talking about before commenting.
  42. BadgerBadger92

    I How can gravitons have anti particles?

    https://physics.stackexchange.com/questions/273918/is-there-a-possibility-for-discovery-of-anti-graviton-i-e-the-graviton-antipar How can a graviton have an anti particle even though they are essentially the same thing? Same thing with the photon. Any help would be great [Mentor Note: The PSE...
  43. lindberg

    I Unruh, Haag et al.: No Room for Particles in Quantum Field Theory?

    In a paper by Bain (2011), particles are left with little ontological value because of the Reeh-Schlieder theorem, the Unruh effect and Haag's theorem. The author claims (and here I am copying his conclusion): First, the existence of local number operators requires the absolute temporal metric...
  44. G

    B Understanding Waves, Particles and Probabilities

    In the ongoing quantum interpretations and foundations thread vanahees71 explained to me that the wave particle duality has been explained by the model where the position of a particle is calculated according to a probability distribution traveling in space. Am I understanding this...
  45. B

    B (ELI5) why can’t massless particles travel infinitely fast?

    I feel like if something is massless it should be able to travel infinitely fast with any amount of energy. When you have something with mass, you would need an infinite amount of energy to push it infinitely fast, but if the thing you’re pushing is massless, you should be able to push it with a...
  46. TheHeraclitus

    I Carlo Rovelli, loop quantum gravity and point particles

    I am reading a popular-science book Reality Is Not What It Seems by Carlo Rovelli, one of the founders of loop quantum gravity. He writes: and and So basically, space (spacetime) is just another quantum field like all the others, and the quanta of this field is the nod. Nods have volume...
  47. V

    B How does exchange of elementary particles result in a force?

    Homework Statement:: I came across the following in an online article. I am unable to understand how these elementary particles cause a force to exist. "Each of the four forces results from the exchange of force-carrier particles.". Above statement is taken from...
  48. I

    B Proving the Existence of Particles: An Exploration

    I studied physics in University a bit out of interest. Curious on how exactly one proves the existence of particles. If I look it up, often the most basic example would be the cathode ray experiment. It seems pretty simple to me, but in my eyes it does not prove the existence of particles...
  49. C

    B Why do subatomic particles change what they do when observed?

    Why do subatomic particles change what they do when observed? Does it matter who is doing the observing? What happens if a non-sentient robot does the observing? How does that compare with a sentient human doing the observing? Thank you.
  50. malawi_glenn

    I LHCb discovers three new exotic particles

    I thought pentaquarks were already considered discovered? https://phys.org/news/2022-07-lhcb-exotic-particles-pentaquark-first-ever.html