Another good signal could be transmission at the frequently of free hydrogen times pi, or times e, or both.
The problem here is not even in the need to spend colossal amounts of energy to signal one's presence. The question is whether such advertising is a good idea if the civilization strives to survive; very likely it is not.
The problem here is not even in the need to spend colossal amounts of energy to signal one's presence. The question is whether such advertising is a good idea if the civilization strives to survive; very likely it is not.