
Science Magazine Podcast Resolving the dispute over the speed of the expanding universe, and seeking new drug targets for cognitive dysfunction
Apr 2, 2026
Mauro Costa-Mattioli, neuroscientist studying the integrated stress response and memory in mice. Daniel Clery, science writer covering methods to measure the universe’s expansion. They discuss using lensed repeating bursts to pin down the Hubble constant. They also explore how turning the ISR on or off affects memory in mice and the potential for ISR-targeted therapies.
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Persistent Hubble Tension Between Two Methods
- The Hubble constant differs by method: standard candles give ~73 km/s/Mpc while CMB cosmology gives ~67 km/s/Mpc.
- Daniel Clery explains the disagreement persists as error bars shrank, suggesting either systematic bias in distance ladders or new cosmology.
Time Delays From Lensed Transients Offer Independent H0
- Gravitational lensing of time-varying sources gives a third, independent route to H0 by measuring time delays between multiple images.
- Clery details how path length and general-relativistic time dilation produce measurable delays useful for distance calibration.
Lens Mass Modeling Is The Key Uncertainty
- Accurately modeling lens mass is crucial because time delays depend on the lens's mass distribution and dark matter content.
- Clery outlines methods: redshifts for cluster membership, galaxy brightness for stellar mass, kinematics for total mass.
