Physics on Hanh Pham's Bloghttps://hanhpham.vercel.app/tags/physics/Recent content in Physics on Hanh Pham's BlogHugoen-usFri, 02 Oct 2026 16:00:00 +0700The Oldest Light: How We Measure 13.8 Billion Years Without a Stopwatchhttps://hanhpham.vercel.app/posts/the-oldest-light/Fri, 02 Oct 2026 16:00:00 +0700https://hanhpham.vercel.app/posts/the-oldest-light/We cannot time the universe with a stopwatch. Here is how astrophysicists measure the 13.8-billion-year age of the cosmos using the Cosmic Microwave Background, atomic recombination, and three independent clocks.