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. D

    I Question on the particles that formed the Earth.

    Full disclosure, I am a creationist, but i want to know the finer points about the big bang and the creation of the universe. So we know that the formation of new rock from lava doesn't make them "day zero" rocks, ie they still would be considered aged when we do radiometric dating. So we know...
  2. C

    N-body random peak velocity of passing particles

    I've been experimenting with my own N-body simulation and I've found a seemingly unsolvable problem. When 2 particles cross paths exactly the peak velocity varies according to how close they are at their closest point and they either fly off the screen or slow right down, I can add an offset to...
  3. deuce123

    I Particle accelerator question -- when the protons "crash" particles are created

    I'm not sure if this is the right place for this question., but I'll ask anyways. So in particle accelerators when the protons "crash" particles are created because of the extremely high amount of energy(example of e=mc^2?)? Is that correct? Also, where do these particles come from? The Higgs...
  4. F

    Group of particles in a magnetic field

    Homework Statement A group of particles is traveling in a magnetic field of unknown magnitude and direction. You observe that a proton moving at 1.50 km/s in the +x-direction experiences a force of 2.25 x ##10^{-16}##N in the +y-direction, and an electron moving at 4.75 km/s in the -z-direction...
  5. ZawL

    Getting energy from kinetic motion of air particles

    I am proposing a piece of equipment a bit similar to Crooke's radiometer with the aim of using kinetic motion of air particles to rotate the mill, without need for an external source of EM radiation. Instead of flat vanes as in Crooke's radiometer, I propose 3-dimensional vanes in the shape of...
  6. Lunct

    B How do we know some particles don't exist until measured?

    I don't know if I am right, but I have read about how some particles do not even exist until measured. How would we know this?
  7. G

    Addition of Angular Momentum for identical particles

    This is the problem I'm trying to understand: Consider two particles with spin 1 without orbital angular momentum. If they are distinguishable, from the rule of addition of angular momentum applied to spin, we'll have states of total spin j=0,1,2. If we have, however, identical particles which...
  8. Dennis Plews

    A LHC - absence of supersymmetric particles

    Thread title edited by moderator. I've not seen any reports from CERN concerning the detection of any putative supersymmetric particles. Is the absence of such detections a problem?
  9. Lunct

    B What kind of difference would particles have?

    In quantum mechanics there is a no cloning rule, so you cannot have two things that are exactly the same. So that must mean that all particles are different. So what kind of unique properties can individual electrons or protons have?
  10. P

    Particle accelerators and timing for particles

    So, I found this document that talks about rf cavities at lhc https://home.cern/about/engineering/radiofrequency-cavities Can you please explain me what i underlined Means? If i understood when the particles achieve the velocity the scientist want them to achieve they get into the cavity when...
  11. Sophrosyne

    B Relationship between Higgs particles and gravitons?

    In trying to understand the relationship between Higgs particles and gravitons, I would like to pose a question on hypothetical question: What would happen if you increase the Higgs field around a planet? It seems it would mean its mass increases, which would mean its gravitation increases...
  12. Burt

    A What Is a 'Black Hole' & What Does It Mean for Particles?

    When they talk about information falling into a black hole, are they referring to the basic defining parameters of the particles falling into the hole?
  13. Chris Miller

    B Gravitational Force and the Endless Supply of Massless Particles

    If gravitational force is caused by a particle (tensor boson) which is massless and so travels at c, why doesn't matter ever exhaust, or even seem to reduce, its supply of these particles?
  14. O

    Question about entropy, particles

    Hello, I am a curious layman, so I might have some misconceptions. I have been pondering some questions, and I was hoping someone might be able to either confirm, or explain this. What I am wondering, if I am understanding this correctly, is why atoms do not experience entropy? If this is true...
  15. G

    Entropy change when the number of particles decreases

    Hi. I found following exercise in a high school textbook: "Compute the entropy change in following process:" The solution is "The number of particles decreases from ##N_1## to ##N_2=N_1/2##. Hence the entropy decreases by $$\Delta S=-k\cdot N_1\cdot \ln{2}\enspace ."$$ I can't quite follow...
  16. J

    I Identical Particle States in a Unidimensional Box

    I have an "unidimensional" box with two identical particles in. My question is , Does it matter in which total spin state is my total function? I mean , if it is a singlet or triplet , one is antisymmetrical and the other is symmetrical, but I only integrate the function in the spatial...
  17. J

    B Do particles "care" about consciousness or simply the data

    I'm curious if there have been any variations to the double slit that specifically looked at whether the particles behavior was determined by the computer keeping the data or if a consious person was there to see it. For example what I had in mind was having an isolated room where the computer...
  18. N

    I Do particles create space over time? Is that expansion?

    If a particle can potentially be transported to any place in space limited only by the speed of light, does that potential amount to an expansion of space? And another question: Does it make sense to define space as any place a particle could go to?
  19. L

    Decay rate of a particle into three particles

    Homework Statement Consider the process of decay of a muon into one electron, one electron antineutrino and one muon neutrino using the Fermi theory. Assume the matrix element is, ignoring the electron's and the two neturino's masses, |\mathcal{M}|^2 = 32G_F^2(m^2-2mE)mE being E the electron...
  20. L

    B Entangled particles and lorentz contraction?

    can lorentz contraction be measured via quantum entanglement with one of the entangled particles moving near the speed of light? would the particle in motion be affected by lorentz contraction? if so, would the particle at rest follow suit and appear affected?
  21. M

    I Are elementary particles subject to inertia?

    Do elementary particles have inertial mass in the same way composite objects have? If yes, does it have an impact on the motion or on the forces that act on them?
  22. E

    Why do photons pass through particles with a delay

    hi everyone. i'm only 16 so please beer that in mind. I've been doing some reading around and have come across the idea that light slows down in an dense medium as a result of the photons moving tough other particles with a slight delay however they retain all factors about them selves apron...
  23. Chris Miller

    B Is QE knowing how to correlate particles' measurements?

    source = http://scienceblogs.com/principles/2012/03/14/entanglement-is-not-that-magic/ It's not clear to me from the above whether this experiment is repeated on the same entangled pair of photons, or a different pair each time. Also, thanks to SR, I have trouble with the "when." Would the...
  24. Nathan Warford

    I Theoretical Models for Sizes of Fundamental Particles

    I am aware that according to the Standard Model of Particle Physics, fundamental particles such as electrons and quarks are treated as point-like particles. However, if fundamental particles are indeed 0-dimentional points with no spatial extent, it creates problems (i.e. fundamental particles...
  25. T

    I Math doesn't add up: stars + planets < particles in universe?

    I see they finally counted all the particles in the universe, it's10 to power of 80 They also counted all the planets: 10 to power of 24 and also counted all the stars: 10 to power of 24 and also counted all the atoms in the Earth: 1.3 x 10 power of 50 Good work everyone! Now, I'm trying my...
  26. davidge

    Thought experiment: charged particles

    Suppose we have two charged particles on the laboratory and two observers A and B. ##A## is inside one of the charges (never mind how) ##B## is sitting at the laboratory In the lab reference frame we accelerate the particles. According to ##A## there will be only electric attraction or...
  27. Sophrosyne

    I Why are gluons considered to be elementary particles?

    Gluons are often depicted as fundamental particles in the Standard Model. But in looking at their mechanism, it seems they are not really fundamental particles in the sense that they are fundamental, indivisible, building blocks. They are mesons- a composite quark-antiquark pair, where their...
  28. G

    Are particles accelerated along magnetic field lines?

    I have a question which puzzled me when I was reading up about auroras. When talking about the interaction of the solar wind and the Earth's magnetic field, the book said that "particles are accelerated along magnetic field lines towards the earth" That didn’t sound quite right, as I was taught...
  29. F

    I Can Quantum Fields be derived from Particles?

    Typically, particles are said to be excitations of quantum fields. My question is whether fields can be derived from particles. Perhaps virtual particles can be summed up in some way to produce a field, for example. Any theories on this? Thanks.
  30. A

    "Seeing" particles with De Broglie visible wavelengths

    Say an electron is fired with the same De Broglie wavelength as blue light. If the electron were to reach your eye, would you see blue, or would something else happen?
  31. J

    B The perfect relativistic quantum particles simulation

    How would a physicists expect a perfect relativist quantum particles simulation to look like? Can anyone give a description of its functionality? Let's say for example, someone would program a simulation, composed of a 4D space-time diagram. Within this simulation are a large amount of quantum...
  32. nabilah

    Solving Distance of Starch Particles in Fluid w/Stoke's Law

    1. Homework Statement I did an experiment to separate different sizes of starch particles (range of size 1 µm to 10 µm). I mixed the starch powder with water in a long cylinder. I have to create model by using long cylinder to separate those starch particles according to their size (<1µm...
  33. A

    B Measuring the energy of particles

    If i have the momentum of the particle, could I measure their energy ? I'm talking about particles in a beam, they are moving in a relativistic speed.
  34. J

    B Rotating Disks: Particle Movement & Spin

    When we rotate a disk, can this process be fully explained by looking worldlines of the particles the rotating disk is composed of, hence their x,y,z,t position "as time passes", or do particles have some kind of "facing direction", hence also spin(not the quantum mechanical notion of spin)...
  35. J

    A Quick question about electron quasi particles....

    http://www.nature.com/news/not-quite-so-elementary-my-dear-electron-1.10471 So when the electron is in the material, it separates into 3 different quasiparticles. But then it says that they cannot exist independently outside of the material. So does that mean the 3 quasiparticles are always...
  36. mfb

    I LHCb observes 5 new particles (excited hadrons)

    Plain old standard model baryons, but 5 at the same time, and with crystal clear peaks in the decay to ##\Xi_c^+ K^-##. Each peak in the figure is a particle never seen before, and the significances of those peaks are about 20 sigma (10 sigma for the 5th one). A broad 6th state might hide around...
  37. P

    Particles in a Magnetic Field Question

    Homework Statement A beam of doubly ionized particles (i.e., twice the elementary charge) is accelerated across a potential difference of 2000 V in a mass spectrometer. They are then passed perpendicularly through a magnetic field of 0.085 T resulting in a radius of curvature 12.5 cm. Calculate...
  38. John Doe

    I Amplitude of particles in the medium of a longitudinal wave

    I was thaught you can create a sinusoidal wave by making a source oscillate with simple harmonic motion in a medium, such as moving one end of a rope up and down to create a periodic transverse wave. For transverse waves, it is easy to see that every particle in the rope moves up and down with...
  39. A

    What is the kinetic energy of particles in plasma

    if i connect an electric current of 30 volts to argon gas to transform it to plasma, what is the average kinetic energy of the argon particles in that plasma?
  40. Eri ep

    Motion of Charged Particles in Field Uniform B-field E=0

    Hello! So I've been working on proving to myself different parts of https://ocw.mit.edu/courses/nuclear-engineering/22-611j-introduction-to-plasma-physics-i-fall-2003/lecture-notes/chap2.pdf packet for several weeks. Under 2.1 Uniform B field, E=0, for the Larmor Radius, I need to know...
  41. J

    I What do tau particles DO? What is their function/purpose?

    Almost ALL introductory articles or videos on subatomic particles virtually NEVER tell you what some particles actually DO: what their function or purpose in the grand scheme of things is. The Tau lepton is a good case in point: even the Wikipedia article is absolutely silent regarding what the...
  42. Lola1

    B Exercises total angular momentum and spin (more particles systems)

    I need websites or books that has quantum mechanical exercises in particular that finds the total angular momentum eigenvalues (for example two spin 1/2 systems). Do you know where I can train?
  43. mangojuice14

    Identical particles and separating the Schrodinger equation

    Homework Statement Two identical particles, each of mass m, move in one dimension in the potential $$V = \frac{1}{2}A(x_1^2+x_2^2)+ \frac{1}{2}B(x_1-x_2)^2$$ where A and B are positive constants and ##x_1## and ##x_2## denote the positions of the particles. a) Show that the Schrodinger equation...
  44. J

    I Virtual Particles and Energy Scales

    Just a basic question which I will ask through an example: An electron and positron can scatter by annihilating to form either a virtual Z or virtual photon, either of which can then pair produce to give an electron/positron pair (amongst an infinity of other processes whose contributions need...
  45. menniandscience

    B Exploring the Effects of Speed on Time and Decay: Unraveling Einstein's Theory

    it is known that einstein's theory has been verified and time slows down for particles that should decay in certain time, takes more time to decay if moving fast. what makes them behave like that, how moving fast makes time to slow down, is it really time or just maybe this has not been...
  46. T

    I Is the KleinGordon Eq the Wave Eq for Spin0 Scalar particles

    If we take the Lagrangian of a spin-0 scalar field and use the Euler-Lagrange equation, we end up with the Klein-Gordon equation. Does that mean that the wave equation of spin-0 scalar particles is the Klein-Gordon equation?Thank you
  47. S

    A Using Fastjet in Pythia to plot distribution of particles

    I am using fastjet in pythia8.I am studying jet formation in pp collisions.I need to plot distribution of transverse momentum of fastest particle in fastest jet formed in 1000 events simulated.But i don't know how to access particle properties after jet formation.Like if I want to know the...
  48. 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...
  49. 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...
  50. 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
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