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. e2m2a

    B Virtual Particles Momentum Transfer

    My understanding is that virtual particles don't really exist. However, they somehow come into existence under certain circumstances. For example, in the Casimir Effect the virtual particles on the outside of the plate now have the capacity to transfer momentum and kinetic energy to the...
  2. Jerome71

    B Do entangled particles always react in an anti-symmetric way?

    I am a non scientist and nonetheless a have the following question: once particles are (intrinsically) entangled do they always react in the opposite way/ anti-symetric to each other? Source https://www.physicsforums.com/forums/quantum-physics.62/post-thread
  3. shrey07

    B Supersymetry versus Anti Particles?

    What is the difference between an anti particle and a super-partner? Would SIMPs fall under the supersymmetry theory, or the anti particle theory, or both?
  4. G

    B Can particles appear from "actual" nothing including no space?

    Hi and thank you for answering questions on complex subjects like this. I’m a non-scientist who is jealous of your brain capacity! Recently, in a discussion with a chemist, he said the particles appearing from nothing might have been the initial cause of the universe. I’m familiar with the...
  5. R

    Combining the Spins of 3 spin 1 particles

    I am having trouble with the normalization part. To get a spin ##|32>## state I could have the following possibilities ##C_1|111110> + C_2|111011> + C_3|101111>## This should be equivalent to ##C_1|11>|21> + C_2|11>|21> + C_3|10>|22>## That is a spin 1 particle and a spin 2 particle that need...
  6. E

    Electromagnetism and the movement of particles

  7. S

    MHB Mechanics- connected particles

    I have no clue how to do this. Pls help
  8. S

    MHB Mechanics- connected particles

    I calculated a=8m/s^2. I don't understand how to calculate the total time.
  9. S

    MHB Mechanics- connected particles

    I got the speed of p when q reaches the pulleys = 1m/s, a= 2m/s^2 Iam getting time = 0.8s for q(b)
  10. S

    MHB Mechanics- connected particles

    Friction= 1/(sqroot12)×80 cos 30= 20N I get two equations T-20=8a and 120-T=12a a=5m/s^2 I don't know how to calculate the time. Also with this value of acceleration tension value is wrong and the textbook ans is 84N
  11. S

    MHB Mechanics- connected particles

    A passenger lift had mass 500 kg. The breaking tension of the cable is 12000N. The max acceleration of the lift is 0.75 m/s^2 a) if the lift travels at its max acceleration, calculate the max mass of the passengers: 1)when the lift is accelerating upwards 2) when the lift is accelerating...
  12. S

    MHB Mechanics- connected particles

    A box of mass 20 kg sits on the floor of a lift. A second box of mass 10kg sits on top of the first box and a third box of mass 5kg sits on top of the second box. When the tension in the lift cable is 4260N, the lift is accelerating upwards at 0.5m/s^2. a) work out the mass of the lift. b) work...
  13. S

    MHB Mechanics- connected particles

    A crate of mass 20 kg is put into a lift. The mass of the lift is 300kg. Find the tension in the lift cable. a) when the lift accelerates upwards at 0.3m/s^2 b) when the lift travels at constant speed c) when the lift accelerates downwards at 0.3m/s^2 For (a) is it T- W-w= ( M+m) a Where T is...
  14. S

    MHB Mechanics- connected particles

    Two smooth pulleys are 8m apart at the same horizontal level. A light inextensible rope passes over the pulleys and a box of mass 5kg hangs at each end of the rope. A third box of mass m kg is attached to the midpoint of the rope and hangs between the pulleys so that all the three boxes are at...
  15. S

    MHB Calculating Tension + Length of String for Connected Particles

    A block of mass 4kg is held on a rough slope that is inclined at 30 degree to the horizontal. The coefficient of friction between the slope and the block is 0.2. A light inextensible string is attached to the block and runs parallel to the slope to pass over a small smooth pulley fixed at the...
  16. S

    MHB Mechanics- connected particles

    A bucket of mass 3kg rests on scaffolding at the top of a building. The scaffolding is 22.5m above the ground. The bucket is attached to a rope that passes over a smooth pulley. At the other end of the rope there is another bucket of mass 3kg, which initially rests on the ground. The bucket at...
  17. S

    MHB Mechanics- connected particles

    A car tows a caravan down a hill. The slope of the hill makes an angle theta with the horizontal, where sin theta = 0.05. The force from the car's engine is a braking force ( a negative driving force). The car has mass 1800 kg and the caravan has mass 600kg. The resistance on the car is 20N and...
  18. L

    B How do you tell when particles are or aren't entangled?

    I'm trying to get my head around the principles of quantum entanglement (would love to get some schooling on the issue but I don't have that kind of money) and trying to discern the actual science from the horrible misconceptions is difficult. I know you can't transmit information faster than...
  19. S

    MHB Mechanics- connected particles

    A horizontal bar of mass 1kg hangs from a pair of parallel vertical rods of negligible mass, attached to either end of the bar. A third vertical rod is connected to the middle of the bar and a 4kg mass hangs from this below the rod. Work out the tension in each of the rods. I got the tension in...
  20. S

    MHB Mechanics- connected particles

    A car of mass 2000kg pulls a caravan of mass 1200kg along a straight horizontal road. The resistance on the car is 20N and the resistance on the caravan is 80N. The max possible driving force from the car's engine is 1900N. The tow-bar will break if the tension exceeds 680N. a) Find the max...
  21. rpthomps

    I Are the daughter particles Ionized when the parent particle beta decays?

    I was wondering if the resulting daughter element is ionized after the parent undergoes beta(or any other kind) of radioactive decay,
  22. C

    System of two spin 1/2 particles in an external magnetic field

    So what I'm not sure on, is calculating the matrix elements for part (iii) with Pauli spinors and Pauli matrices, and then finding the form of the corresponding states. As I don't see how using the hint helps. The following is using the eigenvalues of the spin-operators. Provided what I...
  23. E

    Location of the particles when 1.5 periods of a sound wave have passed

    qn iv. I understand that when 1.5 periods pass, every compression will become rarefaction, and every rarefaction will become compression(someone please correct if wrong) but the answer key shows something else. I'm interpreting the answer key drawing to be 1 compression and 4 rarefactions...
  24. C

    I High energy beta particles (6 to 22 MeV)

    We have a question about highly energized beta particles (6 to 22 MeV). Is it possible fore this radiation to affect the nucleus of an isotope and not just ionize it? In our case a copper-65 and copper- 63 isotope become their unstable neighbors Cu-64 and Cu-62 due to the high beta radiation...
  25. I

    Compacting particles to add density

    Hi, I was wondering if compacting a particle p, you could create an even more dense one. In my theory, you would have a particle of any material, (for example: copper) and you combine it with another copper particle, if you compacted it enough, would the density of the two particles be added up...
  26. ILoveParticlePhysics

    I Calc QED Charge Particle Repulsion/Attraction

    Maybe this will help.
  27. C

    I Are entangled particles really separated?

    I would greatly appreciate answers or perspective on these questions, thank you in advance! Since entangled photons are traveling at the speed of light relative to our spacetime, my understanding is that they experience no time or distance from the moment they are generated to the moment they...
  28. L

    I Physical parameters for spin 1/2 particles

    I am having trouble to understand what it means by "physically relevant real parameters" and how does it help us to specify a quantum system. Let say, we have a state of k half spin electrons? My guess is about the local phase of the spin, and this would make it 2^k parameters since each...
  29. hquang001

    Linear momentum problem with n particles

    To find the mass in other pan, i need to find the force caused by beads on the pan ∴ KEinitial + PEinitial = KEfinal + PEfinal 0 + mgh = ½ mv^2 => v = 3.13 m/s ∴ The change in momentum : p2 - p1 = m ( v2-v1) = m( v - (-v)) = 2mv ∴ F = Δp / Δt = n. m. v How can i apply the rate of 100...
  30. F

    Energy-momentum tensor for a relativistic system of particles

    I think it is quite simple as an exercise, following the two relevant equations, but at the beginning I find myself stuck in going to identify the lagrangian for a relativistic system of non-interacting particles. For a free relativistic particle I know that lagrangian is...
  31. H

    Where did I go Wrong? Solving for Particle Speed with Mass & Charge

    F= 9*10^9 (5*10^-9)^2 / (0.05)^2 a=F/m = F/(3*10^-6) v^2 = u^2 + 2aS = 0 + 2a*0.03 v = 60 Where did I do wrong? Thanks!
  32. S

    Electric Charge is basic property of matter or subatomic particles ?

    In some textbooks it is given that - Electric charge is the characteristic property of matter that causes it to experience a force when placed in an electromagnetic field. and In other textbooks it is given that - Electric Charge is the property of subatomic particles that causes it to...
  33. Fadicando

    B The influence of Gravity on particles

    How does gravity influence an electron beam? And how does it influence the other particles?
  34. Theus_ferreira

    B Modern Physics: Charge of Discovered Particles

    I am studying Modern Physics at graduation and several new particles are being presented, which I had not any contact with until now. I'm wonder if all these particles, which were recently discovered by Physics, have charge whose value is a multiple of the elementary charge of the electron or if...
  35. C

    I Quantum stuff is neither particles nor waves

    When I asked my professors about quantum interpretations like whether it is particles or waves in the double slit experiment. They always say it is just quantum stuff which is neither particles nor waves, so one must not describe them at such. So why do we have so many interpretations. Why not...
  36. QuarkDecay

    Magnetic Mirror and particle trap

    Suppose we have two charged particles A and B released in the center of the Mirror (where the field is minimum). If A's velocity direction is parallel with the Magnetic field of the mirror and B's velocity is perpendicular with the field, then which one is going to get trapped, or escape, or...
  37. lomidrevo

    I Polarization mode symmetries of massless particles

    I am just reading Carroll's textbook on GR, where at the end of chapter 7.4 Gravitational Wave Solutions he discuss how rotational symmetries in polarization modes are related to spin of massless particles. He then explains that we could expect associated spin-2 particles to gravity - gravitons...
  38. LCSphysicist

    Why are fermion states anti-symmetric under exchange operator?

    Let ##L## be the state space of two identical/indistinguishable particles. Let ##L \otimes L## be the state space of the combined system formed by both particle. If the particles were distinguishable, ##LxL## would have four mutually orthogonal states: ## |\phi\rangle|\phi\rangle...
  39. S

    B Are Subatomic particles a form of matter?

    As we know that matter is Anything which has mass and occupies space then are the Subatomic particles like electron,proton and neutron a matter. Is electron a matter ? Is proton a matter ? Is neutron a matter ? As these particles have mass and they occupy space so they are matter, But the...
  40. caybrax

    I Black holes -- Can you chill the particles of a black hole?

    I want to ask if you can theoretically chill the particles of a black hole and if it is possible to achieve it what will happen
  41. I

    B Particles with small Wavelengths passing through huge slits?

    I´´m confused. How can a single photon in the lightspectrum with wavelength of a few hundert nanometers go through both slits in the double slit experiment at the same time. I understand the wave- particle duality and the concepts in principle. My confusion is in the context of little wavelength...
  42. H

    I Bell measurement of distant particles

    Hi Pf I am looking at the figure in wiki about quantum teleportation. https://en.wikipedia.org/wiki/File:Quantum_teleportation_diagram.PNG A wants to send a qubit to B . She receives another qubit from a spdc. so she has to make a Bell measurement on them. Has these qbits to be close in space...
  43. S

    I Indistinguishable particles in separate boxes

    In this video at 02:41 we have two particles in two separate boxes. The voice-over says that the probability that particle P1 is at x1 and P2 is at x2 is equal to the probability that P1 is at x2 and P2 is at x1. The ranges of x1 and x2 are non-overlapping and correspond to the two isolated...
  44. 6

    How to calculate the time until charged particles collide

    How to calculate time until charged particles (Electron/Positron for example) collide starting at velocity= 0 , distance x apart: Using coulombs law, how do I get the velocity and position equation for a pair of unit charged particles? A simple reference link would be great as I know this is...
  45. danielhaish

    I Delay in signaling between entanglement particles

    I know that there isn't any delay that depends on the distance between particles, by the time it take to signal l to arrive from point a to b , but do there is any small delay that doesn't depends on distance . like the Minimum distance between two bodies divided by the speed of light . for...
  46. P

    I Are Virtual Exchange Particles a Valid Concept in Understanding Remote Forces?

    Such particles are virtual, but it should be possible to associate a basic idea with them, as this is the foundation of calculation methods. I think the concept of vacuum fluctuations in the form of virtual, fluctuating pairs of particles is something else. Is the idea of virtual exchange...
  47. P

    Suspended particles and the index of refraction

    Do suspended sub-micron sized particles influence the index of refraction of a liquid?
  48. greg_rack

    Behavior of charged particles in a speed selector

    Considering the device above, which uses electric and magnetic fields placed properly to avoid charged moving particles with velocities different from the ratio ##\frac{E}{B}## to exit, getting deflected upwards or downwards. All that is easily demonstrable by equalling the forces acting on the...
  49. M

    I Separating particles in a zero point energy field

    From my understanding, quantum fluctuations create particle pairs that are usually annihilated. Is it possible to use some kind of force (eg: electromagnetism) to direct and separate antiparticles from normal particles? I believe experiments have proven that it is possible to store positrons...
  50. PhysicsTeacher159

    Is the solution correct? (forces between 3 charged particles)

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