Question

According to what I have heard physics is mainly classified as classical and quantum or modern physics, but relativity is also a vast subject in physics, so is it a separate group in physics or it is a branch of classical or modern physics, and if it is a branch so of which group?

Answer 1

Answer:

I think relativity is a branch of classic physics.

Answer 2

Okay, I am a Quoran, and I have already answered this question on Quora. I am copy-pasting the Quora Answer. But remember:

• This is not plagiarised, I am the one who wrote it, on another platform, and copy-pasting it here, to help people here on Brainly.
• Source of my Quora Answer:

https://www.quora.com/What-is-the-use-of-classical-physics-in-relativity/answer/Saee-Pratapwar

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Answer:

Classical physics is a group of physics theories that predate modern, more complete, or more widely applicable theories. Most usually classical physics refers to pre-1900 physics, while modern physics refers to post-1900 physics which incorporates elements of quantum mechanics and relativity.

Classical physics involves classical mechanics (the study of the movement of fluids and particles), thermodynamics (the study of temperature and heat transfer), and electromagnetism (the study of electricity, magnets, and electromagnetic waves).

Some concepts, such as Electromagnetism are common in both.

Classical physics is no longer used in research -- it says that mass is conserved, time is absolute, there is no laser possible, quantum levels do not exist, and the hypothesis of continuity is true.

In relativity, I don't think it is much used, though a few concepts like Electromagnetism, are very essential, as the theory of special relativity plays an important role in the modern theory of classical electromagnetism. It gives formulas for how electromagnetic objects, in particular the electric and magnetic fields, are altered under a Lorentz transformation from one inertial frame of reference to another.

So answer to your question: Newtonian mechanics, thermodynamics, and Maxwell's theory of electromagnetism are all examples of classical physics. Whereas Relativity forms a part of Modern Physics. So a lot of Classical Physics is not used in relativity, but yeah, Electromagnetism is common in both.

Actually classical physics is the one which deals with the macroscopic world and normal velocities.

There are two deviations from classical physics -- When microscopic particles are treated, we need to use the laws of Quantum physics while if talk of high velocities we need Relativity theory to explain them.

It's not good to classify a particular field as under classical physics or not. Even laws of thermal physics need Quantum principles to be explained because the thermal radiations are also EM waves just the way light waves are. Strictly speaking, all the science is governed by same basic laws and we're trying to find them. We've succeeded in unifying Electricity, Magnetism, Optics and Thermal Physics through EM waves. Further trying of unification is going on.

Classical physics is obsolete concept to be honest; we can use “Quantum and Modern physics” to explain everything.

Classical physics can only be used for ‘macroscopic world’ because it fails miserably in ‘microscopic world’.

Although Quantum physics can be used for both ‘macroscopic’ and ‘microscopic’ world. It works well at both level.

But you know Quantum physics is quite difficult to understand and needs some good level of Mathematics knowledge, so we still use “Classical physics” and “Newton’s laws” for explaining things at ‘Macroscopic level’.

But as I said we can use it at the macroscopic level.

(Thanks for the edit suggestion Ankit :)

Thanks

~Saee Pratapwar