Begin with all the house lights off. At the precise moment (only you know when) every light in the place comes on (throw a few arc lights in there too) and the orchestra hits one gigantic cacaphonous note with emphasis on the basso profundo which never entirely goes away thru the whole piece. I mean, really shake the rafters!   The basso profundo becomes basso ostinato, a note that slowly changes pitch and volume and always lurks in the background regardless of key changes.

Ray Lynch has some interesting ideas in his piece "Tiny Geometries" that you might find inspirational. Whatever. I leave the middle to you entirely. The end? Mankind? The last note or flourish of notes might be on the smallest triangles or finger Zils. The house lights dim throughout and then completely wink out sometime after the last wave fades beyond human hearing. Science can be very dramatic, you know.