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27
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4answers
3k views

Which is more fundamental, Fields or Particles?

I hope that I am using appropriate terminology. My confusion about quantum theory (beyond my obvious unfamiliarity with its terminology) is basically twofold: I lack an adequate understanding of ...
18
votes
3answers
2k views

Are elementary particles actually more elementary than quasiparticles?

Quarks and leptons are considered elementary particles, while phonons, holes, and solitons are quasiparticles. In light of emergent phenomena, such as fractionally charged particles in fractional ...
7
votes
3answers
346 views

References on the non-compositeness of the known elementary particles

What paper(s) or theory(s) describe or prove that the elementary particles that we have determined today cannot be made up of smaller more fundamental particles?
3
votes
2answers
4k views

Speed of a particle in quantum mechanics: phase velocity vs. group velocity

Given that one usually defines two different velocities for a wave, these being the phase velocity and the group velocity, I was asking their meaning for the associated particle in quantum mechanics. ...
1
vote
0answers
102 views

Do particles travel backward and forward in time? [duplicate]

All these classical ideas are pointless and obsolete today, because in quantum mechanics, the particles are completely different objects, defined by quantum motion of fields, not by the location of ...
7
votes
2answers
1k views

Do particles and anti-particles attract each other?

Do particles and anti-particles attract each other? From the very basic understanding that they are created out of nothing mutually and collide to annihilate each other seems to indicate this happens ...
4
votes
6answers
1k views

Good book about elementary particles for high school students?

I need a good book about elementary particles. I am a high school student and don't want anything to technical. I read a brief history of time and the universe in a nutshell but i want something that ...
1
vote
2answers
283 views

Why are atoms particles?

The Oxford English Dictionary definition of particle is as follows: "A component of the physical world smaller than the atom." I read an article in NewScientist and it said "...all particles from ...
13
votes
3answers
509 views

Wave/particle-duality as result of taking different limits of a QFT

There is an account on dualities in quantum field theories and string theories by Polchinski from last week http://arxiv.org/abs/1412.5704 At the end of page 4, he writes the wave/particle ...
2
votes
2answers
319 views

How the nucleon structure has been identified experimentally?

It is known that nucleons (proton, neutron) are composed of partons (quarks, etc.). How was this identified experimentally? In particular, how it has been identified that nucleons comprise of more ...
2
votes
2answers
388 views

Some very basic questions on the Higgs Boson

What exactly is a boson? Is the Higgs boson the cause of gravity or a result of it? Does the collision of particles at the LHC create a gravity field or waves or somehow interact with the gravity ...
14
votes
1answer
5k views

Phase shifts in scattering theory

I have been studying scattering theory in Sakurai's quantum mechanics. The phase shift in scattering theory has been a major conceptual and computational stumbling block for me. How (if at all) does ...
12
votes
2answers
495 views

Why are there no particles in conformal theories?

In Matt Strassler's recent post (here) he makes the statement that scale invariant (I assume he means conformally invariant, more generally) theories have no particles in them. What's the reason for ...
4
votes
2answers
289 views

The concept of particle in QFT

I never learnt QFT and I apologize for my (probably) elementary question. Somebody told me that in QFT a particle is viewed as an irregularity in the field. On the other hand, in an article in ...
7
votes
3answers
318 views

If particles are excitations what are their fields?

After reading these : http://www.symmetrymagazine.org/article/july-2013/real-talk-everything-is-made-of-fields http://www.physicsforums.com/showthread.php?t=682522 It was clear to me that all ...
3
votes
3answers
2k views

are particles “knots” or “kinks” of excitation in a field?

this is my mental picture for how they travel without a medium, how (like water waves) some can't stay still, why they have wave and particle properties, energy/mass equivalence, conservation, etc. ...
1
vote
2answers
137 views

How do particles interact in Bohmian mechanics / pilot wave theory / de Broglie–Bohm theory?

I've read that in the de Broglie–Bohm interpretation of QM, the particle directed by its wavefunction has a trajectory (meaning both position and velocity) and that these are the only properties ...
5
votes
2answers
5k views

Magnetic force doesn't do work and therefore can't change the KE of a particle?

I am having a real hard time understanding the principles behind a question I've come across during test prep. Here is the question: Q: A proton and an electron are traveling in the uniform ...
13
votes
1answer
320 views

As the universe expands, the wavelengths of photons are stretched, and energy is lost. What about electrons?

Will electrons, and other particles, also loose energy as they travel through the cosmos? They have wavelengths. Do they get "stretched"? My guess is that the EM force, somehow, counteracts this ...
9
votes
1answer
3k views

Standard Deviation in Particle Physics

I'm familiar with sigma, and how its usually calculated and used, but would like to know how it's applied to particle physics. I recall reading that the discovery of the Higgs would only be credible ...
3
votes
3answers
363 views

What is a particle?

I posted this elsewhere also and just found this place so copied it down but yeah. I've always wondered this cause I like wondering bout things but I wanna know and it's simple so I should. I got an ...
6
votes
1answer
328 views

Unusual particle effects at CERN

In 2010 there were press reports that CERN had identified unusual properties in particle behavour in collisions. One link here. Here is a partial quote: "In some sense, it's like the particles talk ...
1
vote
0answers
45 views

Acceleration by spherical particles (micron-scale) by an external force

I am looking for an expression for the velocity of a micron sized (1 - 10 micron diameter) sized particles under accelerating forces. I have aerosols in mind. This is what I have in mind The ...
1
vote
4answers
888 views

Questions on wave-particle duality

Wave-particle duality states that a particle has both wave properties and particle properties when one is not observing it. 1) What is an observer? Need it be anything living or can other particles ...
8
votes
1answer
988 views

why is there no ninth gluon?

A teacher of mine told me once that there were no ninth gluon because such a one should be white and interact infinitely far, and no one has been observed. Is there also a theoretical reason?
6
votes
4answers
816 views

Do particle velocities in liquid follow the Maxwell-Boltzmann velocity distribution?

The Maxwell-Boltzmann velocity distribution arises from non-reactive elastic collisions of particles and is usually discussed in the context of the kinetic theory (for gases). There are various ...
3
votes
0answers
228 views

what interactions would take place between a free proton and a dipolariton?

What interactions can be expected to take place between a free proton and a dipolariton, (a) at high energies and (b) at lower energies? A dipolariton is a bosonic quasi-particle mentioned in a ...
1
vote
1answer
103 views

Gillespie's stochastic framework valid for particles in aqueous solution?

Gillespie proposed a stochastic framework for simulating chemical reactions which is predicated on non-reactive elastic collisions serving to 'uniformize' particle position so that the assumption of ...
1
vote
3answers
215 views

Does the Universe have finite number of particles? [duplicate]

I read that the number of atoms in the entire observable universe is estimated to be within the range of $10^{78}$ to $10^{82}$. Does the Universe have finite number of particles? If so, how could it ...
1
vote
2answers
634 views

From where does a particle get the energy to tunnel?

When a particle is made to confine more and more to a particular position it breaks the energy barrier to get out because of the uncertainty principle. But, from where does the particle get the energy ...
1
vote
2answers
130 views

What distinguishes the particles we chose as matter from their antimatter equivalent? [duplicate]

Back before we knew about antimatter we just called everything matter. Ignoring CP-violation for a moment, there is nothing special about matter versus antimatter. Once we knew about antimatter it ...
1
vote
1answer
304 views

Lifetimes of stable particles

What are possible lifetimes of up/down quarks, electronic/muonic/tau neutrinos, photon, gluon? I understand they are said to be stable, but, as I saw on wikipedia, the lower bound for the "stable" ...
0
votes
3answers
97 views

Can two electrons attract each other?

Due to electrostatic repulsion the two electrons will repel each other as they both possess similar charges, lets leave gravitational attractive force out of the picture my question is can there be ...
0
votes
2answers
98 views

NO Uncertainties for particles in their own frames!

Well I had this thought experiment in which a particle observes itself, and something like the following is observed. Taking in mind the uncertainty principle all particles even stopped at 0K jiggle ...
0
votes
2answers
341 views

Does our existence cost us energy?

Anything when it needs to inform its presense such as electromagnetic presense of charged particles and gravitational presense of particles due to their mass does so by sending information of its ...
0
votes
3answers
275 views

Center Of Mass Troubles

I understand the concept of Center Of Mass(com), but I am having a difficult time interpreting the equation of the simplified case of one-dimension. The book I am reading defines the position of the ...
-1
votes
2answers
852 views

What really is the smallest “mass” or “object” in the universe?

Look at this here. With respect to the sciences, the atom is obviously not the smallest piece of mass. Apparently, if people have already broken down the atom in to particles smaller than so, why ...