Theories and Laws of Physics

In summary, the conversation discusses the names and meanings of theories and laws in physics, and how they have evolved over time. It is mentioned that the concept of laws in physics has fallen out of favor and that modern scientists are more aware of the constant change and evolution of knowledge in the field. The Laws of Thermodynamics are noted as an example of a historical law that is still undisputed, but there are other principles such as causality, the principle of least action, and the cosmological principle which are also important to consider. It is suggested to read about these principles to gain a better understanding of why they are considered as such rather than laws.f
  • #1
TL;DR Summary
Who determines what's a Theory and what's a Law?
Hello All

We have Newton's Laws of Motion, which have been superseded by Einstein's Theory of General Relativity.

Who determines what's a Theory and what's a Law?

best regards ... Stef
 
  • #2
Those are just names, some of which evolved historically. I wouldn't worry about it. "Law" is out of favor these days. Too categorical.
 
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  • #3
Those are just names, some of which evolved historically. I wouldn't worry about it. "Law" is out of favor these days. Too categorical.
In the old days, Scientists believed that they were uncovering 'Laws' which had been laid down in the Universe by a deity. Most of us realize that this was probably misguided. Modern day Scientists are only too well aware of the rate of change of our knowledge and that it would be almost presumptuous to expect to find a 'Law'. In a year / decade / century, your law would have add-ons to account for new evidence.
 
  • #4
Are there any historical "Laws" in physics which are still undisputed?

I would nominate the Laws of Thermodynamics, now more than 100 years old. I believe what eventually became the Second Law was formulated in 1824, ie almost 200 years ago,
 
  • #5
Are there any historical "Laws" in physics which are still undisputed?
Disputed is the wrong word. It implies that there is no need to dig deeper. For example, General Relativity showed us that Newton's Law of gravity is not the whole story on very large scales.

It may surprise you, but there are some things in physics that are even more fun to think about than laws. The principle of causality is one. The principle of least action is another. But the easiest one to understand is the cosmological principle. I suggest that you read some about all three of those, they may arouse your interest. Then ask yourself, "Why are these principles rather than laws?"

https://en.wikipedia.org/wiki/Causality
https://en.wikipedia.org/wiki/Principle_of_least_action
https://en.wikipedia.org/wiki/Cosmological_principle
 
  • #6
Are there any historical "Laws" in physics which are still undisputed?

I would nominate the Laws of Thermodynamics, now more than 100 years old. I believe what eventually became the Second Law was formulated in 1824, ie almost 200 years ago,
You may want to read about recent work on the fluctuation theorem. There are experiments which show violations of the 2nd law on short time scales.
 

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