# A very ambitious question

1. Nov 28, 2008

### 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?

2. Nov 28, 2008

### 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.

3. Nov 28, 2008

### samalkhaiat

[

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

sam

Last edited: Nov 28, 2008
4. Nov 29, 2008

### atyy

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

5. Nov 29, 2008

### Gear300

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

6. Nov 29, 2008

### 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

7. Nov 29, 2008

### 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.

8. Nov 29, 2008

### 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.

9. Nov 30, 2008

### Llewlyn

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 wich 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.

10. Nov 30, 2008

### ZapperZ

Staff Emeritus
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.

Last edited: Nov 30, 2008
11. Nov 30, 2008