It's not accurate to say that modern physics is "more valid" than classical physics. They are both valid in their respective domains. Here's a better way to understand the relationship between classical and modern physics:

Classical Physics:

* Domain: Describes the behavior of objects at everyday scales and speeds (think baseballs, cars, planets).

* Successes: Explains motion, gravity, electricity, magnetism, and many other phenomena that we experience directly.

* Limitations: Breaks down at very high speeds (close to the speed of light), very small scales (atoms and subatomic particles), and extremely strong gravitational fields.

Modern Physics:

* Domain: Deals with phenomena at the very small (quantum mechanics) and very fast (special relativity) scales.

* Successes: Explains the behavior of atoms, light, nuclear reactions, and the universe on a large scale.

* Limitations: While highly successful, there are still some unsolved puzzles and open questions in both quantum mechanics and general relativity.

The key point: Classical physics is a simplified model that works extremely well in most everyday situations. Modern physics is a more sophisticated and complete description of reality, particularly at extreme scales. But, both are valid within their respective domains:

* Classical physics is still used in everyday engineering, technology, and many other fields.

* Modern physics is essential for understanding the fundamental nature of the universe, and it has led to technologies like lasers, semiconductors, and medical imaging.

Think of it like this: If you want to build a bridge, classical physics is perfectly adequate. But if you want to understand the behavior of light in a laser, you need modern physics.

Therefore, rather than saying one is "more valid" than the other, it's more accurate to say that modern physics is a more comprehensive and fundamental theory that extends classical physics to a wider range of phenomena.