I heard that weak interaction is often between hadrons like (proton/neutron) but it interacts with leptons like electrons and neutrinos
however if the weak interaction only works on tiny distances how would a electron/neutrino ever come close enough to a proton/neutron for this force to even be significant in day-to-day
@Downgoat particles aren't little balls and their interactions aren't like tiny billiard balls colliding. Particles don't have precisely defined positions. An analogy often used is that the particle is like a fuzzy cloud.
@Downgoat So a particle scattering event is like two clouds overlapping. As long as some bit of one cloud overlaps some bit of the other cloud there is a probability of the particles interacting, though (especially for the weak force) that probability may be very low.
One more question: in the strong force between quarks. Are the gluons carrying color charge virtual? If not, where does the energy come from for QCD to take place or am I significantly misunderstanding how it works
You need to be careful about taking the concept of virtual particles too seriously.
Virtual particles don't really exist. They are a computational device - a way of breaking down a very complicated calculation of the interaction between particles into manageable chunks.
@ACuriousMind it's continuous in one direction (time), but discrete in another (different brains) - as such, some $I_j\left( t_1\right)$s are closer to $I_i\left( t_1\right)$ than $I_i\left( t_2\right)$
That is one interesting take on the philosophy of identity
What I am saying doesn't probably make any sense. But, what if we take space time and add in each point a random generator, or a white noise, or any other stochastic process.
Would it help to connect quantum mechanics and relativity? What about adding a fluctuation term?
For example one option...
if i understand correctly. virtual particles don't 'exist' in the typical sense but you can observe their interactions (e.g. virtual photons with electrons)?
@Downgoat no. You can observe interactions, and those interactions can be calculated as a perturbative expansion. And the terms in the expansion can be represented as Feynman diagrams.
But those Feynman diagrams do not represent particles, virtual or otherwise, even though they look like the interactions of particles. The Feynman diagrams represent an integral called the propagator.
So the interaction is certainly real, but the virtual particles used to calculate it are not real.
@Downgoat slereah's comment has some justification behind it but is probably more confusing than helpful at this stage :-)
@Slereah every particle started somewhere, i.e. no earlier than the Big Bang, and given time every particle will interact somewhere. So you can argue this means all particles are virtual, but whether this is useful is debatable.
There is lots of experimental evidence that the electromagnetic field exchanges energy with atoms in discrete chunks, and if we call these chunks photons then photons exist. Which is all very well, but my guess is that you’re really interested to know if the photon exists as a little ball of ligh...
@Phase yes, if you gave the colliding neutrons enough energy they would form black hole, and yes if you gave them more energy they would form a bigger black hole.
@KyleKanos I guess the serial downvoting will be reversed, though the question is who is doing it and why. Presumably the community mods will be able to identify the offending account.
I don't quite understand how to do a problem I am working on:
> An airplane is flying horizontally with speed 1000 km/h (280 m/s) when an engine falls off. Neglecting air resistance, assume it takes 30 s for the engine to hit the ground. (a) How high is the airplane?