New JWST data confirm that the Hubble tension is exacerbating

During the first billion years of our universe’s history, the rate of expansion of the universe slows and distant galaxies slow into stagnation from our era, as the density of matter and radiation decreases. However, over the past 6 billion years, distant galaxies have been accelerating their stagnation, and the rate of expansion, although it continues to decline, is not heading towards zero. Two different ways of measuring the rate of expansion give conflicting values; The actual rate of expansion remains controversial.

We can look randomly back into the universe if our telescopes allow it, and the galaxy cluster must reveal a specific distance scale – the acoustic scale – that must evolve with time in a certain way, just as the acoustic “peaks and valleys” in the cosmic microwave background reveal this. Scale too. The evolution of this scale, over time, is an early remnant that reveals a low expansion rate of about 67 km/sec/million blocks.

Building the cosmic distance ladder involves moving from our solar system to stars, to nearby galaxies, to distant galaxies. Each ‘step’ carries its own uncertainties, especially the rungs at which the different ‘runs’ of the ladder connect. However, recent improvements in the distance ladder have shown just how strong his results can be.

Back in 2001, there were many different sources of error that could bias the best distance-ladder measurements of the Hubble constant, the expansion of the universe, to significantly higher or lower values. Thanks to the diligent and careful work of many, this is no longer possible, since errors have been greatly reduced. New JWST work, not shown here, has reduced errors related to Cepheid and period luminosity errors further than shown here.

Variable star RS Puppis, with its light echoes shining through interstellar clouds. Variable stars come in many varieties. One of them, Cepheid variables, can be measured both within our galaxy and in galaxies up to 50-60 million light-years away. This enables us to extrapolate distances from our galaxy to distant galaxies in the universe. RR Lyrae and AGB branch stars can be used in a similar way.

The stars closest to Earth will appear to move cyclically with respect to the more distant stars as the Earth moves through space in orbit around the sun. Before creating the heliocentric model, we were not looking for “shifts” with a baseline of ~300,000,000 km over about 6 months, but rather a baseline of ~12,000 km over one night: the diameter of the Earth as it rotates on its axis. The distances to the stars were so great that the first sight, with a baseline of 300 million km, was not discovered until the 1830s. Today, we measured the parallax of more than a billion stars with the European Space Agency’s Gaia mission.

As recently as 2019, there were only 19 published galaxies that had distances measured by Cepheid variable stars in which Type Ia supernovae were also observed to occur. We now have distance measurements from individual stars in galaxies that also hosted at least one Type Ia supernova in 42 galaxies, 35 of which have excellent images from Hubble. These 35 galaxies are shown here.

Using the cosmic distance ladder means piecing together different cosmic scales, as one always worries about uncertainty where the different “runs” of the ladder connect. As shown here, we are now down at least three “runs” on that ladder, and the whole set of measurements agree with each other amazingly well.

Standard candles (left) and standard rulers (right) are two different methods that astronomers use to measure the expansion of space at different times/distances in the past. Based on how quantities such as luminosity or angular size change with distance, we can infer the expansion history of the universe. Using the candle method is part of the distance ladder, yielding 73 km/sec/million blocks. The use of a ruler is part of the early indication method, yielding 67 km/s/Mpc. With the new JWST data, the mystery about the expansion rate of the universe has deepened even further.