- #1
Omega0
- 205
- 51
The "Tree of Physics"
Hi,
I know this is pretty complicated in the end but I would be interested in something like "the Tree of Physics", more exactly speaking it would be a graph (and please don't take it literally how I describe the complexity).
Say for example I have one particle without interaction I simply have nothing. If I have n particles without interaction (not moving relative to each other) I have a reason to define a coordinate system. If they are moving I need to think about what coordinate system we have (SRT) and I have to think about boundary conditions. If for example relative speed is << c you don't need SRT. But you have BC so now it is important that the particles are allowed to have mass. If they have mass it is interesting which speed they have (momentum).
If there is a BC you need to define the interaction of a particle with the bounds. You need to take in account if particles are allowed to collide (if so what it means for the momentum, the "energy" is interesting) - but it's more: QM teaches that one single particle is enough to behave different "if the scale is small enough".
If the number of particles is bigger then say 1M it makes no sense to track them all. Now we think about statistics and as we already have added the feature "energy" we try to describe the system statistically (pressure etc.)
Now let's make it more complicated, let's allow interaction by forces. Let's focus on the "well known" interactions, electricity and gravitation.
For more than 3 particles we have an analytic problem but nature has much more. So we use numerics - but a planet is not a particle. Say Phobos as the satellite of Mars. In a planet or moon or simply a bar we have lots of particles and summing it up we get tensor effects.
So here we see that "simple" mechanics is not simple at all.
I didn't write about the complex mechanics of a rotating bar falling into the Earth atmosphere, thermodynamics, electrodynamics, the coupled equations and so on.
Hopefully you didn't fell asleep while reading, my question is: Does there exist a graph ("tree") to explain when which methods need to be applied or in other words: When which model is sufficient?
Jens
Hi,
I know this is pretty complicated in the end but I would be interested in something like "the Tree of Physics", more exactly speaking it would be a graph (and please don't take it literally how I describe the complexity).
Say for example I have one particle without interaction I simply have nothing. If I have n particles without interaction (not moving relative to each other) I have a reason to define a coordinate system. If they are moving I need to think about what coordinate system we have (SRT) and I have to think about boundary conditions. If for example relative speed is << c you don't need SRT. But you have BC so now it is important that the particles are allowed to have mass. If they have mass it is interesting which speed they have (momentum).
If there is a BC you need to define the interaction of a particle with the bounds. You need to take in account if particles are allowed to collide (if so what it means for the momentum, the "energy" is interesting) - but it's more: QM teaches that one single particle is enough to behave different "if the scale is small enough".
If the number of particles is bigger then say 1M it makes no sense to track them all. Now we think about statistics and as we already have added the feature "energy" we try to describe the system statistically (pressure etc.)
Now let's make it more complicated, let's allow interaction by forces. Let's focus on the "well known" interactions, electricity and gravitation.
For more than 3 particles we have an analytic problem but nature has much more. So we use numerics - but a planet is not a particle. Say Phobos as the satellite of Mars. In a planet or moon or simply a bar we have lots of particles and summing it up we get tensor effects.
So here we see that "simple" mechanics is not simple at all.
I didn't write about the complex mechanics of a rotating bar falling into the Earth atmosphere, thermodynamics, electrodynamics, the coupled equations and so on.
Hopefully you didn't fell asleep while reading, my question is: Does there exist a graph ("tree") to explain when which methods need to be applied or in other words: When which model is sufficient?
Jens