Normal databases store rows in tables, like a spreadsheet. To handle time you bolt on a start and an end column and write tricky checks for overlaps. It works, but it stays slow, because the database has no idea what time is.

Δt flips that. Time is the whole database. A booking is just a stretch on one line, and two bookings collide when they cover the same moment, like the flight and the hotel above. That is the whole idea, and it answers "what is free?" in well under a millisecond.