For quite a long time, we have known that the universe is expanding. The red light shift (a drop in value for light waves that are getting farther away, sort of like the drop in tone you hear as an ambulance passes you and the siren moves away) makes clear that galaxies are moving away from us. But we don’t know how fast this expansion is happening. The standard model of physics depends significantly on what value we give to the Hubble constant – the rate of expansion of the universe.
One value for the Hubble constant, determined from the background microwave radiation evident all over the cosmos and measured by the Planck space mission, is 67.4 km/s/Mpc. Other measurements, based on techniques using constant stars to measure distances to galaxies, come to a value of around 74. A difference, given the precision of the two ways of measuring, which is quite significant.
This July a scientific conference reported new findings on the Hubble constant, and almost all the measurements were close to or greater than the 74 derived from star distance measurements. One exception, by a respected research team using different types of stars, came up with a figure of 69.8, about half way between the other two figures.
Another new technique, measuring gravitational waves to determine the Hubble constant, may provide insight over the next five to 10 years. The first measurement of such a gravitational event a few years ago suggested (with a very large error rate) a value of 70. Scientists are looking forward to the results of this new gravitational research.
The divergence of values for the Hubble constant is unsettling or exciting, depending on how you look at it. It suggests that some of our fundamental understanding of the universe is not clear. If these differences are not due to some systemic error, it’s possible that other aspects of reality require new and better theories. Maybe our understanding of dark matter and dark energy (which are constructs that make the current physics theories work) will need to change.
This “crisis” in our understanding of the physics of the universe excites scientists and leads to much theoretical work on how our created universe is structured. The openness among scientists to new ways of understanding God’s creation is something we as Christians might want to think about in our understanding of God’s Word. We can be very unwilling to see God’s revelation in new and creative ways. Rather, we argue that our traditions and past understandings are normative for approaching Scripture today. We are suspicious of new and different interpretations and quick to denounce approaches that have not been part of our history.
But sometimes we need to take a step back and recognise that our understanding of God’s Word has changed significantly over time and be open to new approaches. Jesus, and then Paul, took an approach to the Old Testament that was quite shocking to the religious leaders of the day. In Nicodemus we see the sincere puzzlement of the Jews. In our age, with its explosion of knowledge about everything from the creation to our nature as God’s image bearers, it behooves us to take a tentative and humble approach to our understanding of God. That God loves us is clear from his gift of his son. We can trust this God to care for us even if we do not have a definitive, complete understanding of his Word (and world).