In classical physics, the concept of inertia, as described by Newton's first law of motion, states that an object will remain at rest or move with a constant velocity in a straight line unless acted upon by an external force. However, when it comes to quantum particles, the situation is fundamentally different.
In quantum mechanics, particles are described by wave functions that represent the probability distribution of their positions and momenta. The behavior of quantum particles is governed by the laws of quantum mechanics, which have distinct characteristics from classical physics. Quantum particles do not have well-defined positions and momenta simultaneously, but rather exist in a superposition of states until measured or observed.
The concept of two quantum particles being "comoving" with respect to each other at a constant speed is not applicable in the same way as in classical physics. The state of motion of quantum particles is described by wave functions and can be entangled or correlated, but their behavior is not accurately captured by classical concepts like constant velocity or inertia.
In quantum mechanics, the principle of superposition allows particles to exist in multiple states simultaneously, and their behavior is probabilistic. This means that quantum particles can exhibit wave-like properties such as interference, diffraction, and tunneling, which are not observed in classical systems.
In summary, while classical physics concepts like inertia and constant velocity have limited applicability to quantum particles, the behavior and motion of quantum particles are fundamentally different and require a quantum mechanical description.