In the theory of special relativity, time dilation occurs when an object or observer is moving relative to another object or observer. When an object moves at a significant fraction of the speed of light, time appears to pass more slowly for that object relative to a stationary observer. This phenomenon is described by the principle of time dilation.
Now, let's consider the case of a photon, which is a particle of light. Photons, by definition, travel at the speed of light in a vacuum. According to special relativity, time dilation applies to objects with mass and not to massless particles like photons. From the perspective of a photon, its own lifetime is instantaneous. This means that, within its own rest frame, a photon does not experience the passage of time.
However, from the perspective of an observer in a different reference frame, the lifetime of a photon appears to be finite. As an observer moves relative to the photon, their relative motion leads to time dilation effects. Consequently, the observer measures the photon's lifetime to be extended compared to what the photon itself experiences.
In summary, within its own rest frame, a photon has no perception of time passing, and its lifetime is effectively instantaneous. However, when observed from a different reference frame, time dilation occurs, and the measured lifetime of the photon appears to be longer.