How Fast Is The Universe Really Expanding?

Understanding the Hubble Constant

• 💡 The Hubble Constant is the fundamental quantity that measures the current rate of the universe's expansion.
• 🧠 Historically, its value was debated, ranging from Edwin Hubble's initial 500 km/s/Mpc to a factor-of-two uncertainty (50-100) in the 1970s, before the Hubble Space Telescope refined it to 72 km/s/Mpc.

The Hubble Tension

• ⚠️ A significant "Hubble Tension" currently exists, referring to the discrepancy between local measurements of the expansion rate (typically 70-73 km/s/Mpc) and values inferred from the Cosmic Microwave Background (around 67 km/s/Mpc).
• 🔬 This difference, if real and not due to measurement errors, could indicate that there's something unknown about cosmic evolution or the standard model of cosmology.

Measuring Cosmic Distances

• 🔭 Local measurements of the Hubble Constant rely on accurately determining distances to galaxies using