system
Given the following post, respond as if you're commenting on Reddit:
human
Is there a limit to how long a radio wave can be? Would extremely long waves be of any use?
gpt
Frequencies lower than 1 oscillation within the age of the universe don't produce anything you could call an electromagnetic wave, and similarly wavelengths longer than the Hubble length are not meaningful waves. Apart from that there is no limit, it just gets harder to detect radiation the lower the frequency gets.