Particles Definition and 1000 Threads

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

    Why does the PE of particles during steam condensation decrease?

    The answer says it decreases but shouldn't it increase? according to the kinetic model, KE accounts for particle vibrations. PE accounts for the attractive forces between particles. Since condensation means gas -> liquid, it means the particles become closer and hence the attractive forces...
  2. theblazierbroom

    Deriving the particle's motion using numerical integration

    When I used differential equation techniques, I found the function of x and v to be a negative exponential function. However, based on the notes, I believe the problem wants me to use finite summations as the relevant equations above. This stumps me because the acceleration is dependent on the...
  3. mister i

    I Number of Higgs "particles" per unit volume

    Is the number of Higgs "particles" per unit volume constant (or Higgs field value), even in expanding space?
  4. A

    Prove v<c for particles with m>0 using two identities

    I can't figure out how to prove this using only those two identities? I mean in general, I could prove it easy when using relativistic equations, and showing that if ## v = c##, the denominator becomes 0, and if ## v>c##, the denominator becomes an imaginary number (a negative square root)...
  5. K

    B Matter/Anti-Matter in a Vacuum

    I do not know if this is the place to post this. I am not a great physicist. Actually, I was an Electronic/Electrical Technician before I retired. I learned that the vacuum of space is filled with matter/antimatter particles popping out of nothing and destroying themselves almost instantly. My...
  6. Grinkle

    B Expected Earth-relative velocity of interstellar particles

    I recently saw (on a pop-sci video) an opinion that the engineering challenges involved in interstellar travel are insurmountable. One of the challenges discussed was how to protect a ship moving at, say 0.2c, from being disintegrated over time by collisions with interstellar particles. That...
  7. H

    I What is the meaning of "same direction" for spin measurement?

    Hi Pfs, I read that pairs of entangled particles were measured on earth along a same direction and that the distance between them was greater than 1000 kilometers. What is the définition of a "same direction" on earth? is Is it related to the direction of a very distant galaxy or somethig like...
  8. Heisenberg7

    Closest distance of approach between 2 charged particles

    A few hours ago, I tried solving this problem and I'm still not quite sure if I've made a mistake somewhere or perhaps the guy in the video is wrong? Anyway, here's my solution: In the problem we're given that the total kinetic energy of of these 2 charges at this instant(look at the picture)...
  9. Ignorantsmith12

    I What if particles are moving near light speed and one slows?

    I tried to solve this problem independently, but given how confused I am about the twin paradox and the concept of relativity of simultaneity, I have no confidence in my solution. Suppose a collection of particles has been moving very close to the velocity of light relative to the Cosmic...
  10. SWIRF

    I Breaking the Light Speed Barrier?

    If we have a pair of super-asymmetrical entwined particles, and move them a light year away so that they retain their quantum entanglement, and we set a clockwise spin as 0 and a counter-clockwise spin as 1. Would it be possible to transmit binary data faster than the speed of light? If we hold...
  11. arivero

    A Why do the proton and electron have equal and opposite electric charge?

    The most common explanation I know is that anomaly cancelation implies the sum of electric charges of each particle must cancel generation-wise, so 3 Q(Up) + 3 Q(Down) + Q(electron) = 0, and electroweak doublets imply Q(Up) - Q(Down) = Q(neutrino) - Q(electron), so with Q(neutrino) = 0 it solves...
  12. 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...
  13. 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...
  14. 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...
  15. 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...
  16. 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##...
  17. 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.
  18. S

    Can Two Particles Have Multiple Collisions in a Single Interaction?

    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...
  19. 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?
  20. 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 ?
  21. 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...
  22. 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?
  23. 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?
  24. 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
  25. 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?)
  26. 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...
  27. 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...
  28. 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...
  29. 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?
  30. 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,
  31. 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...
  32. 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?
  33. 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.
  34. 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...
  35. 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!
  36. S

    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...
  37. 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...
  38. 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.
  39. M

    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...
  40. Vilius

    Why Don't GM Counters Detect 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...
  41. 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...
  42. 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+...
  43. emilmammadzada

    Particles transporting in MCNP5

    Is it possible to transport only photon , electron and neutron in mcnp5?
  44. 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...
  45. 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...
  46. 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...
  47. 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...
  48. 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...
  49. 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...
  50. 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...
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