Language
Country/Area
No result found
From classical to quantum: Why can't classical mechanics explain the strange phenomena in the microscopic world?
With the advancement of science and technology, quantum mechanics has gradually become the main theory for understanding the microscopic world. However, the principles of classical mechanics cannot fully explain many microscopic phenomena. This forces us to rethink the nature of matter and the way we observe and measure it.
The state of a quantum system is a mathematical entity that embodies knowledge of the system and whose construction, evolution, and measurement are prescribed by quantum mechanics.
Limitations of classical mechanics
In classical mechanics, the state of motion of an object is usually defined by its position and velocity. Through precise data and formulas, we can predict the behavior of objects. For example, when firing a cannonball, if we know the angle and initial velocity of the barrel, we can calculate the flight path of the cannonball. However, when this calculation is applied to microscopic particles, the results become unreliable.
The arrival of quantum mechanics has made us realize that the operating rules of the microscopic world are very different from those of the macroscopic world. At the microscopic scale, the state of particles is no longer determined, but is represented by probability distributions. This means that even if we know the initial state of a particle, we cannot determine its future state, only predict its likelihood.
The initial state of classical mechanics can be clearly predicted, but in quantum mechanics even a certain value at the initial moment cannot give a clear future state.
The nature of quantum states
In quantum mechanics, quantum states are the core of describing systems. They are divided into pure states and mixed states, where pure states represent a definite state, while mixed states are statistical combinations of multiple states. These quantum states are complex in nature, but the rules by which they operate are well-defined. In fact, all physical properties can be obtained by measuring these quantum states.
|Ψ(t) = ∑ Cn(t) |Φn
Representing the evolution of a quantum state over time allows us to understand the behavior of particles in a deterministic way. It is worth noting that this randomness does not mean complete chaos, but is subject to certain laws.
Singularity of measurement
The measurement process is the most mysterious part of quantum mechanics. In classical physics, a measurement does not affect the state of the system, whereas in the quantum world, making a measurement changes the state of the system. For example, measuring the position of a particle will change its momentum, a phenomenon known as the uncertainty principle.
The impact of measurements on quantum systems cannot be ignored. Each measurement will have a certain impact on the system and change its original state.
Quantum entanglement and non-locality
Quantum entanglement is a peculiar phenomenon in which the states of two quantum systems are interdependent. No matter how far apart they are, once one of the systems is measured, the state of the other is determined. This property challenges our traditional understanding of locality and independence, raising many deeper philosophical and physical questions.
Therefore, in the face of this wonderful phenomenon in the microscopic world, we cannot help but ask: How are knowledge and reality intertwined in this quantum universe full of uncertainty?
