Darkness?
Rafael and the others paused for a moment, and then realized that all the light in the hall had disappeared, leaving only the skylight in the roof that let through a hint of light, casting down onto the stage.
Everyone's gaze naturally focused together, and Lynn's figure soon appeared before them, a faint smile on his face. "Ladies and gentlemen, welcome to today's magic seminar."
The hall, already somewhat noisy, immediately became as loud as a festival celebration; a variety of comments could be heard, and some even shouted out loud.
"Lynn, regarding your method of measuring the central angle of the Earth's core, there are a few points I still don't understand, and what exactly do 'cube,' 'square' and 'root' mean?"
"What exactly is the radius and volume of the planet beneath our feet? Is it eight hundred and sixty billion cubic kilometers or one trillion two hundred and thirty billion cubic kilometers?"