Can you recommend a sci-fi novel where humans can transform into a mass of energy or a robot in the future? I saw it in a science fiction anthology.

The story took place in the future. Humans could become a mass of energy or robots to obtain eternal life, and they had the ability to change the galaxy. In the face of low-level civilizations, their strength was almost divine. One of the details was that the protagonist's kind could change the physical laws of a planet at will, stopping the scientific development of the planet's creatures so that they would not threaten their own existence. This short story was included in a collection of science fiction novels. There were also other science fiction writers such as Liu Cixin's Devouring Empire. The protagonist of the story was called Yu or Zhou. His mother was a mass of energy. She created the protagonist with the closed strings of the universe. Before she died (or before she became an astronomical star in the universe), she opened up a galaxy for the protagonist to provide him with energy. In this setting, this "energy" was almost like a "god" in the galaxy. For hundreds of millions of years, the protagonist had been living by absorbing the energy of the galaxy? Until the energy of the galaxy was used up. Then, he encountered a ball of photon? I can't remember the plot anymore. I was shocked by this grand world view for a long time, but after returning the book, I forgot about it for a long time. Ask for short story title QAQ