Theory:Doctor Who television discontinuity and plot holes/Blink: Difference between revisions

::The Angels are only affected by being directly observed, as described by the doctor, observing their shadow is merely seeing the obstruction of light as they pass across a light source and is not a tangible part of the actual creature, so they are unaffected.

:::But observing them is merely seeing the reflection of light as they pass across a light source that's behind you instead of on the other side. That's how vision works--it's all just photons hitting eyeballs. However, maybe there is a difference between photons (seeing them) and an unexpected absence of photons (seeing their shadow). This may sound silly, but it's actually something that real physicists argue about--see, for example, the various eraser experiments, or the quantum bomb detector (although most physicists who argue about this do so to argue that the Copenhagen Interpretation is nonsense, which would mean "quantum locking" is nonsense).

: That's a very cute point. Search for "can shadows move faster than the speed of light" for more on this. Basically, shadows do not contain information, and while shadows can indeed move faster than the speed of light, you cannot use them to transmit information at that speed. In that sense, it makes perfect sense in the fiction of this episode that observing shadows does not count. (Never mind the details of "quantum locking" and the measurement problem of quantum mechanics and all that -- it's fiction and entertainment, and it works crazy well.)