Are non-perturbative methods in physics limited to quantum physics?

In summary, non-perturbative methods are crucial in quantum field theory and have applications in quantum electrodynamics. There can also be mathematical problems without perturbative solutions. It is uncertain if classical physics can have non-perturbative solutions, but there are examples of classical non-perturbative solutions in quantum field theory books. Non-perturbative effects can also be present in general relativity, as seen in the Schwarzschild, Reissner-Nordstrom, and Kerr solutions. There is also a significant amount of research on non-perturbative stabilization of rogue waves in the context of water waves. Additionally, there is a large body of work on completely integrable systems, many of which are relevant to
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ohwilleke
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Non-perturbative methods are critical is some parts of quantum physics, but it isn't clear to me if they are ever present in classical physics.
Non-perturbative methods are critical in parts of quantum field theory, such as QCD, and have at least some applications in quantum electrodynamics. You can also have mathematical problems that don't have perturbative solutions.

But, it isn't clear to me if classical physics can ever have non-perturbative solutions, and I'm not sure how to find an answer.

In particular, I'm interested in whether non-perturbative effects can be present in general relativity, or if, in the area of gravity, that are necessarily confined to quantum gravity theories.
 
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Criticality of second phase transition in statistical physics may belong to what you are looking for.
 
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ohwilleke said:
But, it isn't clear to me if classical physics can ever have non-perturbative solutions, and I'm not sure how to find an answer.
Of course. For example, many QFT books have chapters on topological solutions such as solitons, instantons and magnetic monopoles, which are classical non-perturbative solutions.
ohwilleke said:
In particular, I'm interested in whether non-perturbative effects can be present in general relativity
Of course. The classic examples are Schwarzschild, Reissner-Nordstrom and Kerr solution.
 
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ohwilleke said:
it isn't clear to me if classical physics can ever have non-perturbative solutions
There is a huge amount of work on completely integrable systems. Many of them are related to problems of physics.
 

FAQ: Are non-perturbative methods in physics limited to quantum physics?

What are non-perturbative methods in physics?

Non-perturbative methods in physics are techniques used to analyze systems where perturbation theory, which relies on small expansion parameters, is not applicable. These methods are essential for studying phenomena that involve strong interactions or large coupling constants, where the usual perturbative expansions do not converge or are insufficient to describe the system accurately.

Are non-perturbative methods exclusive to quantum physics?

No, non-perturbative methods are not exclusive to quantum physics. While they are prominently used in quantum field theory and quantum chromodynamics, they also play a significant role in other areas of physics such as statistical mechanics, condensed matter physics, and classical field theory. These methods are crucial in studying systems with strong correlations or interactions that cannot be treated perturbatively.

What are some examples of non-perturbative methods?

Examples of non-perturbative methods include lattice gauge theory, which discretizes spacetime to study quantum field theories; the renormalization group, which analyzes changes in physical systems as they are viewed at different scales; and instanton calculus, which involves summing over non-trivial topological solutions in field theory. Other methods include variational techniques and numerical simulations.

Why are non-perturbative methods important in physics?

Non-perturbative methods are important because many physical phenomena cannot be accurately described using perturbative approaches. For instance, in quantum chromodynamics (QCD), the theory of strong interactions, the coupling constant becomes large at low energies, rendering perturbative techniques ineffective. Non-perturbative methods are essential for understanding phenomena such as confinement, where quarks are permanently bound within hadrons, and for studying phase transitions in statistical mechanics.

How do non-perturbative methods differ from perturbative methods?

Perturbative methods involve expanding quantities in terms of a small parameter and solving the resulting series approximately. These methods work well when the expansion parameter is small. In contrast, non-perturbative methods do not rely on small parameters and instead address the full complexity of the system directly. This often involves numerical simulations, exact solutions, or summing over non-trivial configurations that cannot be captured by perturbative expansions.

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