Heisenberg's uncertainty principle is a fundamental principle of quantum mechanics that states that it is impossible to simultaneously know the exact position and momentum of a particle with absolute certainty. The uncertainty principle applies to all particles, regardless of their size or speed, including photons and electrons.
Even if a particle, such as a photon or an electron, is at rest, the uncertainty principle still applies. This principle arises from the wave-particle duality of quantum objects. In the case of a particle at rest, the uncertainty principle manifests as the uncertainty in its position and momentum. The more precisely you try to measure the position of a particle, the less precisely you can determine its momentum, and vice versa.
In other words, even if a particle is not moving, its quantum wavefunction is still spread out in space, and there is an inherent uncertainty in its position and momentum. This uncertainty is a fundamental property of quantum particles and cannot be eliminated, regardless of their state of motion.
It's important to note that the uncertainty principle does not imply a limitation in our ability to measure the position and momentum of a particle due to technological constraints. Instead, it reflects a fundamental aspect of the nature of quantum particles. Therefore, even if a particle is at rest, the uncertainty principle still holds true.