What are the most fundamental laws of physics?

[snoopies622]

I once heard physics described as "a handful of equations that explains everything". If one were to make a list of the most fundamental physical laws -- fundamental in that all other physical laws could derived from them -- what would be on it?

 

[cesiumfrog]

Fundamental physics today is still incomplete, but basically:
- you would go to a particle physicist to learn what the fundamental particles that exist are (and the rudiments of how they interact). See "standard model".
- you would learn QFT (today's equivalent of Schroedinger's equation) to understand how to use that information to calculate everything else (and so you could derive electrodynamics, Newton's laws, fluid dynamics, thermodynamics, chemistry, biology, maybe even social sciences, etc, except..)
- you also need to understand Einstein's field equation, since in today's understanding gravity is completely different to everything else.

 

[samalkhaiat]

[

QUOTE=snoopies622;1978967]I once heard physics described as "a handful of equations that explains everything". If one were to make a list of the most fundamental physical laws -- fundamental in that all other physical laws could derived from them -- what would be on it?

\delta S[Q] = \delta \int d^{4} x \ \mathcal{L}(Q, \partial Q) = 0


sam

 

[atyy]

- you also need to understand Einstein's field equation, since in today's understanding gravity is completely different to everything else.

What about this? So at least we can think of gravity and the standard model together for all current observations? Though I gather that even whether QCD works at low energies was not really known till recently.

Introduction to the Effective Field Theory Description of Gravity
http://arxiv.org/abs/gr-qc/9512024

 

[Gear300]

[\delta S[Q] = \delta \int d^{4} x \ \mathcal{L}(Q, \partial Q) = 0sam

What does that mean?...something with strings?

 

[samalkhaiat]

It is called "the principle of least action". It is an expression of a general behavior in nature. The action (Hamilton's) principle is one of the most fundamental achievements of theoretical thought. Since the time of Hamilton, practically all observed phenomena have been described by equations shown to be the consequences of the action principle. I put the action principle in a category I call super-laws.

sam

 

[Gear300]

Interesting...to be honest, I have little idea as to what was said, but it sounds to be an important equation indeed. I'll look it up.

 

[snoopies622]

I found a nice list here

http://en.wikipedia.org/wiki/List_of_laws_in_science

but they're not all fundamental and they don't mention quantum field theory or the standard model.

I am enjoying this thread by the way and appreciating everyone's contributions. I hope there will be more, since this is a matter which seems to involve some personal opinion.

 

[Llewlyn]

I once heard physics described as "a handful of equations that explains everything". If one were to make a list of the most fundamental physical laws -- fundamental in that all other physical laws could derived from them -- what would be on it?

You may be interested also in a (very short) article of Anderson (discover of positron) called "More is different": look at "Science", 1972. The essence is that at some scale the way in which costituents interact play an important role, fundamental as the "fundamental laws" that govern the costituents theirself. For example, we are made by atoms but as humans we show a "complex" behaviour like falling in love or politics apparently completely disconneted by atom's laws. This "fundamental" studies are part of theoretical physics of today, hope u enjoy.

Ll.

 

[ZapperZ]

You may be interested also in a (very short) article of Anderson (discover of positron) called "More is different": look at "Science", 1972. The essence is that at some scale the way in which costituents interact play an important role, fundamental as the "fundamental laws" that govern the costituents theirself. For example, we are made by atoms but as humans we show a "complex" behaviour like falling in love or politics apparently completely disconneted by atom's laws. This "fundamental" studies are part of theoretical physics of today, hope u enjoy.

Ll.

Er.. Phil Anderson did not discover the positron. He's a theorist in condensed matter physics. He got his Nobel Prize for his theoretical work in broken symmetry principle. You are confusing him with Carl Anderson.

What you are pointing out is what is known as "emergent" phenomena. There are plenty of article already written on this by Anderson, Bob Laughlin, and David Pines. All of them (and the majority of CM physicist) do not buy into the reductionist idea of the "Theory of Everything". See:

1. http://www.pnas.org/cgi/reprint/97/1/28.pdf
2. http://www.pnas.org/cgi/reprint/97/1/32.pdf
3. http://arXiv.org/abs/hep-th/0210162
4. R.B. Laughlin, Rev. Mod. Phys., v.71, p.863 (1999).
5. P. Anderson, Science v.177,p.4 (1972).

Zz.

 

[Llewlyn]

Er.. Phil Anderson did not discover the positron. He's a theorist in condensed matter physics. He got his Nobel Prize for his theoretical work in broken symmetry principle. You are confusing him with Carl Anderson.

arg... bad mistake :-(
thanks for pointing it out.

Ll.

 

[snoopies622]

I haven't studied the standard model yet. Does it contain within it all the established laws of physics besides gravitation?