Quantum physics, or quantum mechanics, is a branch of physics that deals with the behavior of matter and energy at very small scales, typically at the level of atoms and subatomic particles.

Quantum physics, or quantum mechanics, is a branch of physics that deals with the behavior of matter and energy at very small scales, typically at the level of atoms and subatomic particles. It fundamentally challenges our classical understanding of how the universe works. Here are some key concepts:

1. Wave-Particle Duality: Particles like electrons and photons (light particles) exhibit both particle-like and wave-like behavior. This means they can behave like discrete particles in some situations and like waves in others.
2. Quantization: Energy levels in quantum systems (such as atoms) are quantized, meaning they can only take on discrete values. For instance, an electron in an atom can only occupy specific energy levels.
3. Superposition: A quantum system can exist in multiple states simultaneously, known as superposition. For example, an electron can be in more than one location at once, but when measured, it “collapses” to a single state.
4. Entanglement: When two particles become entangled, their properties become linked, no matter the distance between them. A change in the state of one particle will instantaneously affect the state of the other, even if they are light-years apart.
5. Heisenberg Uncertainty Principle: It states that there is a limit to how precisely we can know both the position and momentum of a particle at the same time. The more precisely we measure one, the less precisely we can measure the other.
6. Quantum Tunneling: Particles can pass through barriers that would be insurmountable in classical physics, a phenomenon known as tunneling. This is essential in many technologies, including tunnel diodes and nuclear fusion.

These concepts, while strange and counterintuitive, have been experimentally verified and are foundational to technologies like lasers, MRI machines, and even quantum computing.