Is Dark Energy Getting Stronger?
Summary
This Space Time journal club episode examines a new Nature Astronomy paper suggesting the cosmological constant may not be constant, potentially increasing over time. The study uses the UV-to-X-ray brightness ratio of 1,600 quasars as a new standard candle to measure cosmic expansion history, revealing discrepancies with the standard Lambda-CDM model. These results hint at a "Big Rip" scenario where dark energy tears the universe apart, though the hosts caution that measurement errors or systematic biases may still explain the data. The episode also briefly discusses Richard Branson’s Virgi…
Topics discussed
Introduction to the Lambda CDM model and new clues
Reviewing the current accepted model of the universe
The Hubble tension and the crisis in cosmology
Limitations of supernovae and the need for new tools
Quasars as potential standard candles
Using X-ray and UV ratios to measure quasar distance
Analyzing the new quasar Hubble diagram data
Implications for dark energy and the Big Rip
Alternative explanations and future research directions
Discussion on Virgin Galactic and the term spaceship
Other spacecraft projects and Stratolaunch
Host's experience on Richard Branson's Necker Island
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