NASA is notoriously tightlipped when it comes to addressing space anomalies reported by the public – UFOs during launches, strange doors or buildings or statues on Mars or the Moon and the like. The space agency is almost as secretive about its own unusual discoveries, but that changed this week with a very public announcement that data collected by the Hubble space telescope shows something “weird” is going on in the universe … a strange discrepancy which might only be explained by “brand new physics.” Are we really ready to discard the old physics?
"The Hubble constant is a very special number. It can be used to thread a needle from the past to the present for an end-to-end test of our understanding of the universe. This took a phenomenal amount of detailed work."
In a space coincidence which illustrates the importance of their common astronomer namesake, Edwin Hubble, the Hubble telescope data in question concerns the Hubble constant – the constant of proportionality in Hubble’s law which states that galaxies are moving away from Earth at speeds proportional to their distance so that the farther away they are, the faster they are moving away from Earth. While the Hubble constant has proven its worth by aiding in the discovery of the "dark energy" which accelerates the universe's expansion, the Hubble telescope, along with others, has collected data which calls the Hubble constant into question -- a discrepancy between the expansion rate as measured in the local universe compared to independent observations from right after the big bang which predict a different expansion value. A constant is no longer a constant if it’s not constant … right?
"You are getting the most precise measure of the expansion rate for the universe from the gold standard of telescopes and cosmic mile markers."
In a paper to be published in the Special Focus issue of The Astrophysical Journal, Nobel Laureate Adam Riess of the Space Telescope Science Institute (STScI) and the Johns Hopkins University in Maryland throws his support behind the Hubble telescope, which recently completed its latest collection of cosmic distance markers – a project called SH0ES (Supernova, H0, for the Equation of State of Dark Energy). Those markers would be Cepheids, stars that brighten and dim periodically in the Milky Way and other galaxies which NASA calls the “gold standard of cosmic mile markers.” (What is it with NASA and gold standards?) Since its launch in 1990, the Hubble telescope has supported and refined the Hubble constant, eventually in 2009 reaching its goal of verifying its accuracy to one percent – putting its value at 73 plus or minus 1 kilometer per second per megaparsec. Unfortunately, that’s not what it was predicted to be.
“The expansion rate of the universe was predicted to be slower than what Hubble actually sees. By combining the Standard Cosmological Model of the Universe and measurements by the European Space Agency's Planck mission (which observed the relic cosmic microwave background from 13.8 billion years ago), astronomers predict a lower value for the Hubble constant: 67.5 plus or minus 0.5 kilometers per second per megaparsec, compared to the SH0ES team's estimate of 73.”
Using measurements by the European Space Agency's Planck mission (which observed the relic cosmic microwave background from 13.8 billion years ago just after the Big Bang), the expansion of the universe should be slower than Hubble says it’s growing. That revelation caused NASA to announce that “something weird is going on, possibly involving brand new physics.” Why a brand new physics? Because the theory of an expanding universe uses Einstein's field equations of general relativity. If the constant is wrong, then the most general principles to the nature of the universe might be wrong too. Does Adam Riess really want to prove Einstein wrong?
“Actually, I don't care what the expansion value is specifically, but I like to use it to learn about the universe."
That sounds like a safe, NASA-approved answer while it figures out what to do next. The Hubble telescope has been collecting this data for 30 years and, as anyone following the news of James Webb Space Telescope knows, is nearing retirement. Can we wait 30 more years for Webb to build a new data set? Or is it so much better than Hubble that it can resolve this problem in less time?
What would Einstein do?