I was thinking about the Photoelectric Effect and Blue-Shifting when I came up with a thought experiment that I couldn't think of an answer for. The thought experiment is as follows:
A metal plate is set up to measure the photoelectric effect. Travelling toward the metal plate is a space-ship travelling at near C. The space-ship is emitting light that is of a frequency slightly below the threshold frequency of the metal plate.
From what I understand, from the metal plates frame of reference the light emitted by the space-ship would undergo Blue-Shifting and hence have a higher measured frequency, exceeding the threshold frequency of the metal plate and causing a current to be measured.
However from the space-ship's frame of reference the light would not undergo Blue-Shifting and thus would be below the threshold frequency of the metal plate, thus a current would not be measured.
Could someone please explain where I've gone wrong, and what would actually happen in this situation.