# Studying Topics for hunting -- which part of physics is the most accurate description of the nature

1. Mar 17, 2017

### rahaverhma

In today's world, iwant to know which part of physics is the most accurate description of the nature. I know in coming time, i may get interested in some other topic. But toward which topic should I set my foot forward to?

2. Mar 17, 2017

### Choppy

Hi Rahaverhma - there might be a bit of a language barrier to people understanding your question. Could you expand on what you mean?

3. Mar 17, 2017

### rahaverhma

In today's world, iwant to know which part of physics is the most accurate description of the nature. I mean for ex. Classical mechanics is a handsome description of mechanisms at macroscopic level but general relativity is more better description than that. So, I want to go with world in forward direction not just limiting myself to ancient level. And, GR was an example, even if something is better than that you can say about it.

But toward which topic should I set my foot forward to?

4. Mar 18, 2017

### Choppy

Usually in physics people gravitate toward a specific sub-field because of the problems they are interested in solving and the opportunities in that sub-field rather than how accurately it models nature. All models break down at some point. Some are useful for solving particular types of problems. And sometimes worrying about accuracy sets you up for diminishing returns.

"Nature" is pretty broad. Perhaps you're enquiring about grand unified theories or the "theory of everything?"

One thing about learning classical models first, is that most of the more complex models are built on these. You need to know classical mechanics to understand quantum mechanics, for example. And because there are conditions under which classical mechanics breaks down, doesn't mean that it isn't useful for solving even some very modern problems. @Dr. Courtney for example, has written about research work that he's done in ballistics, which I would imagine draws quite heavily on classical mechanics.

5. Mar 18, 2017

### Dr. Courtney

Classical mechanics is THE tool for modern ballistics, with few exceptions. Interior ballistics uses lots of important results from thermodynamics and chemistry also.

Quantum mechanics is THE tool for most of atomic physics, either non-relativistic (easier to apply) or relativistic (harder to apply, sometimes needed for accuracy).

The fundamental tradeoff is between theoretical applicability and practical issues - like being able to actually make a prediction with the model before the sun goes cold.

6. Mar 18, 2017

### JoePhysics

A couple of comments. First of all, accuracy is only relevant if your measuring device is capable of distinguishing, say $3.365854$ and $3.365857$, where one result is obtained with a classical theory and the other with a more modern extension. For example, if Mercury's precession were not $574.10\pm 0.65$ arc-seconds per century, but something a lot smaller which we would have no realistic way of discerning at least not until telescopic equipment technology improved dramatically. This is why in physics one speaks of domains of validity for specific theories.

Second, even in classical physics, there still remain some outstanding questions: hydrodynamic turbulence comes to mind, as does ball lightning. The Painlevé paradox of rigid body dynamics, a topic that rests squarely within the confines of classical mechanics, was only resolved at the end of last century!

It is humbling to think that we have managed to peer back into the past and see what the Universe was like a brief moment after the Big Bang, yet we still do not fully understand how water behaves as it leaves the faucet of our bathroom sink.