This question is about a phenomenon in the Dark Forest, part of the Three Body Problem science-fiction trilogy often considered 'hard science'. Be warned: there are major spoilers below for those who have not read the first 2 books of the trilogy. Also note: this was first asked in sci-fi.SE but it was deemed off-topic for its focus on real-world science, and it was recommended I ask it here.
This Three Body Problem series has surprised me with how far-fetched some of its concepts seem, yet how well-founded some of them are in real-world cutting-edge physics.
There is a point right around the end of the second book, the Dark Forest, where a critical turn in the plot is based on an idea that seems very far-fetched to me. A plot excerpt is included below to describe the far-fetched, plot-turning idea:
... Luo Ji reveals that he is wearing a biometric watch similar to the one constructed by Wallfacer Rey Diaz. Project Snow was a ruse, the bombs are intended to selectively block light from the sun, creating a message sent out to the galaxy with the exact coordinates of Trisolaris and Earth. If Luo Ji dies, the bombs will detonate revealing the interstellar message. He threatens to kill himself if the Trisolarans fail to surrender. Trisolaris, facing destruction of their home planet, and Earth, capitulates, and acknowledges... via https://en.wikipedia.org/wiki/The_Dark_Forest#Plot
Specifically, the idea that
bombs are arranged in such a way that their detonation can selectively block light from the sun sufficiently to create a message sent out to the galaxy with the exact coordinates of one or two or any celestial bodies
It may be worth noting that
end up playing a major role in the book, and the
bombs are stellar nuclear, strong nuclear fusion bombs considered capable of destroying the solar system if used on Mercury and the Sun.
Also, earlier in the story a basis for this technique is first explored:
The location of a planet was effectively communicated in more peaceful conditions by broadcasting three star-map images out into space using radio waves and a technique for electromagnetic wave amplification by sending the signal to our Sun. Imagine SETI having found a way to greatly amplify signals, then trying to communicate broadly to the universe the specific location of a specific celestial body.
Is there any real-world feasibility for this defensive maneuver?