Why we measure the universe | Professor Wendy Freedman | TEDxChicago

Quick Overview

Professor Wendy Freedman explains that the Hubble Tension, a discrepancy in measuring the Hubble Constant (the universe's expansion rate), is being addressed by combining three major astronomical breakthroughs: Henrietta Leavitt's discovery of Cepheid variable stars as cosmic beacons, Edwin Hubble's discovery of universal expansion, and the development of CCDs to pierce cosmic dust, all culminating in the construction of massive next-generation telescopes like the Giant Magellan Telescope to achieve higher precision and potentially reveal new physics.

Key Points: The Hubble Tension arises from a persistent discrepancy between two primary methods of measuring the Hubble Constant (H0), the rate of the universe's expansion. Henrietta Leavitt's discovery of Cepheid variable stars allows astronomers to measure distances to galaxies, serving as 'cosmic beacons'. Edwin Hubble used Cepheid data to show that galaxies are moving away from us, proving the universe is expanding. CCDs (Charge-Coupled Devices) allow for infrared observations, which pierce cosmic dust that obscures light from distant stars like Cepheids, improving measurement accuracy. The Webb Telescope, launched in 2021, offers 10 times the image clarity of Hubble, allowing better measurement of Cepheid brightness variations. The speaker's team is working on next-generation telescopes, like the 80-foot diameter Giant Magellan Telescope, to resolve the Hubble Tension, which currently sits between an H0 value of 67 (from early universe data) and 73 (from local universe data). The ultimate goal of resolving this tension is to potentially uncover new physics beyond the Standard Model of Cosmology, which currently accounts for only 5% of the universe's composition (atoms).

Context: Professor Wendy Freedman discusses the long-standing cosmological problem known as the Hubble Tension—the disagreement between different methods of calculating the Hubble Constant, which dictates the expansion rate and age of the universe. She frames this challenge within the context of three historical breakthroughs that underpin modern distance measurements: Leavitt's work on Cepheid variables, Hubble's observation of cosmic expansion, and the advent of CCD technology that overcomes dust obscuration.