Reasons for natural occuring forces

[sudhirking]

Well, similair to the reasons behind gravity as in theory of relativity, i would like to know the reasons behind electro magnetism. i would also like to know how exactly the strong force holds hardons toghether and produces atomic stability in varying spaces. Also, why and how is the strong force there. I would want to know the same for the weak force. Thank you for your time and dedication to science.

 

[malawi_glenn]

You should go to the Gauge Theories of the Standard Model. Do you want textbook reference or articles/pdf-tutorials?

In order to grasp the ideas you need to be quite familiar with Quantum mechanics formalism, Lagrangian Theory of classic fields and some Group Theory.

This paper can helt you to get those concepts before trying to grasp the standard model:
http://arxiv.org/abs/0810.3328

We also want to understand how the residual strong force binds hadrons togheter, two of the most successful ways to understand this is Chiral Perturbation Theory and Lattice QCD, here is a introductory article about Chiral Perturbation Theory (N.B. one need to know the Standard Model in and out before attempting this)
http://arxiv.org/PS_cache/hep-ph/pdf/0703/0703274v1.pdf (A very good lecturer and nice person aswell)

 

[spidey]

Well, similair to the reasons behind gravity as in theory of relativity, i would like to know the reasons behind electro magnetism.

Electromagnetic force is because of exchange of virtual photon between the charged particles. It can be visualized as follows, suppose if i throw a ball to you, i will move back and you will also move back because of momentum. Same thing happens in electromagnetic force. If there are two electrons they exchange virtual photons,like we exchanged ball and for some distant observer it will look like the electrons are moving apart(repel) since he cannot see the virtual photon.

I don't know why they should exchange virtual photon,why not sit simply

 

[malawi_glenn]

They must exchange virtual photons due to local U(1)-gauge invariance. Spidey you only said HOW EM-force works on quantum level, not WHY.

 

[DaveC426913]

They must exchange virtual photons due to local U(1)-gauge invariance. Spidey you only said HOW EM-force works on quantum level, not WHY.

Science doesn't answer why; only how. To answer why, you need to move this to the philosophy forum.

 

[malawi_glenn]

It depends on WHAT LEVEL, on the ultimate level, science doesn't answer "why". But on smaller levels, such as "why does balls fall to the ground when you drop them from a height" can be answered in a physical way. But the question "why is there gravity at all" and so on must be moved to another level.

The question "why is there local U(1) gauge invariance?" must similarly be moved to another level.

The OP wanted to know why and how the electromagnetic force, weak force, and strong force comes about on the same level as we understand gravity in general theory of relativity. So by just answering "by virtual particle exchange"

How many credits in philosophy of science at unversity level do you have on your CV dave?

You are also mixing what kind of questions we are dealing with here. The question asked was in the realm of physics, not metaphysics. A metaphysical question could be "why does life exists on eart?", and that question can have answers both in metaphysical realms and physics realm. The physics realm can answer it that it was due to the conditions of the primordial Earth etc and the metaphysical answer could be "since God wanted life to exist".

The question asked by OP was a physical question, and can be answered with a "physical why".

So as you see dave, your answer is quite unbalanced and shallow.

 

[sudhirking]

If there are two electrons they exchange virtual photons,like we exchanged ball and for some distant observer it will look like the electrons are moving apart(repel) since he cannot see the virtual photon.

Thank you so much for giving me a deeper understanding odf Em on a quantum state, as before i thought of EM as a force in general like space-time for gravity (disregarding the graviton as i am not a believer in that). But one more question...

I thought that in quantum leap, electrons absorb photons and i have a separate thread onthis. However i got a reply stating that they do not absrb the phton rather the atom absorbs it which causes higher energy in electrons. Well, an lone electrons, how do they absorb phtons. How are they even produced (phtons)??

 

[sudhirking]

They must exchange virtual photons due to local U(1)-gauge invariance.

May u please explain local U(1) - gauge invariance?

 

[malawi_glenn]

Well free eletrons do absorb photons, look at the compton effect for instance.

 

[malawi_glenn]

I have explained local U(1) gauge invariance last week in this forum,

https://www.physicsforums.com/showthread.php?t=279743

The requirement to have the fields changed by a unobservable phase which leaves the lagrangian invariant requires the existence of electromagnetic fields and interaction.

 

[sudhirking]

Electromagnetic force is because of exchange of virtual photon between the charged particles. It can be visualized as follows, suppose if i throw a ball to you, i will move back and you will also move back because of momentum. Same thing happens in electromagnetic force. If there are two electrons they exchange virtual photons,like we exchanged ball and for some distant observer it will look like the electrons are moving apart(repel) since he cannot see the virtual photon.

Well, I am probably asking a stupid question, but won't these virtual phtons rebound off each other. It would seem strange to release them at different intervals, as it would cause Electromagnetic phenomenons that are inevitably non-existant?

OHH NO NVM ABOUT THIS QUESTION.. IT WAS A STUPID QUESTION as virtual phtons just hold magnitude and not a definite space, so they dont't rebound off each other..


HOWEVER, is this influx of the em force instantaneous and spntaneous, or not??

 

[DaveC426913]

It depends on WHAT LEVEL, on the ultimate level, science doesn't answer "why". But on smaller levels, such as "why does balls fall to the ground when you drop them from a height" can be answered in a physical way. But the question "why is there gravity at all" and so on must be moved to another level.

Yep. It occurred to me that's what the OP really meant. I justed wanted to tease out the loaded term so we can step around without startling or enraging it.

 

[sudhirking]

You should go to the Gauge Theories of the Standard Model. Do you want textbook reference or articles/pdf-tutorials?

Are there any online tutorials explaining each of teh fundamental forces.. (excluding gravity)..

 

[sudhirking]

I have explained local U(1) gauge invariance last week in this forum,

https://www.physicsforums.com/showthread.php?t=279743

The requirement to have the fields changed by a unobservable phase which leaves the lagrangian invariant requires the existence of electromagnetic fields and interaction.

um i went there, but to be honest, i cannot understand the math becuase i am actually younger than i may appear. I am no even in algebra 2 yet, i am in middle school, but soon i will be in algebra 2-- freshman year. then i will; be in precal, then cal, then next lvl of cal.

So pls, since math is only the numerical expression of logic, explain the conceptual , verbal logic behind the math of this local u(1) gauge invariance..

 

[sudhirking]

Well free eletrons do absorb photons, look at the compton effect for instance.

i wikied the compton effect, BUT I CANNOT UNDERSTAND THE DIAGRAM.. according to waht i can understand, it is a mid energy photon-matter interaction so its frequency is mid range in the em spectrum. Anyway, in this range of wave, does taht respective photon just simply "hit", may I say, the elctron causing recoil in both electron?? If so, this reasons for em which u said is the local gauge invariance?? Then obviously there is some flaw with my thoguhts. PLease note it out and criticize me..

 

[ZapperZ]

This is a prime example where these two guidelines should be paid attention to when dealing with a discussion in this forum:

1. Clearly reveal your background when you are asking a question. The best way to learn is to build on top of what you already know. If you fail to do that, the responses you will get can easily go over the top of your head, and you'll waste the time and effort of people who have already responded, because they've written something that you would not have understood.

2. When responding to a question, see if you can tell the level of understanding of the OP. If not, then don't respond, ask for clarification, or probe the understanding of the OP by seeing if certain things makes sense to him/her. If you don't do this, then you're liable to have put in an effort that be beyond the comprehension of that person.

Zz.

 

[sudhirking]

Well then, i have an understanding of gravity.. basics on em and qm, very little on the weak and strong force... That is where i stand.. and pls, don't give any math involved, just us concpets...

Zz.

 

[ZapperZ]

Well then, i fully undersand gravity.. basics on em and qm, very little on the weak and strong force... That is where i stand.. and pls, don't give any math involved, just us concpets...

Zz.

I doubt that you "fully understand gravity". You know how to talk the talk, but you really don't understand the significance of what you have said. I can easily prove to you that you don't. If I give you, say, an infinite plane of mass, can you figure out how to find the gravitational field at a certain distance away from the plane?

Now you can easily say "Yeah, but that's just math!", and that's where I will, in turn, show that you haven't understood the physics. Physics isn't just saying "What goes up must come down". Physics must also say when and where it comes down, and that means clear, mathematical description that gives both qualitative and quantitative predictions. Lacking in those two implies that you haven't "fully" understood the concept.

I know it isn't going to be easy to be patient and wait until you get more solid background in both mathematics an intro physics, but at some point, you simply just have to wait until you have the ample background knowledge to be able to comprehend some of these things. That is the sad reality that you have to face at some point. If not, then each time you get a response, people will have to keep on backtracking to explain the answer of the answer of the answer, and that can get very tiring and cumbersome very quickly, and the thread can get off-topic very fast!

Zz.

 

[sudhirking]

. Physics isn't just saying "What goes up must come down". Physics must also say when and where it comes down, and that means clear, mathematical description that gives both qualitative and quantitative predictions. Lacking in those two implies that you haven't "fully" understood the concept.

OK (not neccesary to come down hard). You are indeed right in teh fact that i need more mathematical education and background, but math itself is just the numerical expression of logic. If you do understand something "fully", and a literal fully, math would already well be instated, and i am agreeing with you that i don't understand gravity fully, but i thought you would understand that i don't know the math behind it, when i said, i don't know the math behind it. So when I said i understand it fully, i meant it excluding the math becuase i said i do not know the math. And to your question, one would need to know the mass of all the matter in that particular universe, and also a specific distance, and then they would use the math. To go off with what you are implying, mathematics does give a qualitive and quantitive predictions, but that in turn is just logic. With this logical understanding of space-time, one has to see all other relations and variables within a given universe (and back again to answer your questions) as they may pose as enomilies later when solving your question. To fully give a specific answer to it.. the answer is Yes (i am being sarcastic please do not attak me on this, it is for mere humor), I can figure out how to find the gravitational field at a certain distance away from the plane perhaps in some years with math...

i will edit my post and say that i have an understanding of gravity..

I am sorry, but i will not take a "break" from learning more even if i don't have a great , current, mathetical knowledge, but i can and will try to understand the principles of quantum phenomenons. When i do figure the language when i go to high school and college, i will apply them to what i have learned and go over them thoroughly. I want to know the truth, and i shall NOT supress my curiosity becuase someone tells me too! I will continue to use these forums to ask questions (and mind i will start to point out please no math, yet) and even if i get bblocked from you or some1 else, i will buy more QM books and try hard to understand. There is no reason why u cannot continue to seek the truth, just because i cannot see some truths. I mean that's what science is all about, answering questions, and math is important to that, but it is not needed as everything occurs within the principle. though i shall say it is VERY HARD to figure out the principle in a given situation and numerical expression makes it relatively easier, it is also not needed.

 

[malawi_glenn]

You can't learn physics without math kid.

If you want to understand the physics you should put effort in learning math first.

You can ofcourse read popular science books about QM and particle physics, but keep in mind that those books are inacurate and will acually prevent you from learning the real concepts once you have enough math to do it.

I recall from my class in introductory QM that it was the guy who had read the most popular science books who had the hardest time struggelning to understand what was going on. He had certain expectations, which the REAL physics could not live up to.

Physics IS MATH applied to the nature. Of course you can in some cases translate the math into human language: "Gravity is the effect that masses bend space-time" is such an example.

Subhiriking, ZZapper is a senior physicists, and you should pay attention to his advices. And not tell him that he is "not able to continue seeking the truth" (whatever truth is in this context). ZZapper doesn't want to kill your curiosity, he want to learn you how to use it. Focus on the correct things and learn one thing at the time. Be paitent, don't rush yourself into something like a kid high on drugs, be rational.

It is funny that a guy from high school knows better than real physicsits what physics and science is. And that math is not needed since "everything occurs whitin the principle" (what principle?)

And if you want to study the "truth", you should go into philosophy. A physical theory can't be true/false in the real sense. A physical theory can only be more or less plausible to describe nature. One example is the quantum field theory approach to nature, one ends up with things like virtual particle exchange and so on, but does they exists in nature? The general answer is "no", they are just mathematical tools. But indeed the outcome of such particles existing only on the piece of paper makes the numerical predictions of that theory testable and verified to the 7th digit or so! (Quantum electrodynamics is one of the best tested and verified theories in physics) So one can then ask the question: "Does the particle under consideration exchange virtual particles?"

It was an appetizer.

Now my suggestion is that you start studying some philisophy of science litterature, since you seems to be very eager to learn science, and you make bold and naive claims about what science is and what truth is and so on. So start by studying those concepts.

The secondly, learn math, math is the language of physics. No matter what you think, it is the language of physics, and physics must use math to even BE physics. Don't think anything else.

Third, be patient, some things in physics CAN NOT be explained in layman terms at all. You will learn physics eventually.

 

[Vanadium 50]

ZapperZ and Glenn made some very good points. I'd encourage you to think about what they wrote.