The most recent measure of the expansion rate of the Universe is indeed and has confirmed with more certainty than ever that we have a real cucumber on our hands. Once again, the result has shown that the universe is expanding much faster than it should be based on the conditions immediately after the Big Bang.
The rate of expansion of the universe is called the Hubble constant, and it was incredibly difficult to determine.
According to data from the Planck satellite, which measured the cosmic microwave background (the conditions of the early universe only 380,000 years after), in the Big Bang the Hubble constant should be 67.4 kilometers per second per megaparsec with an uncertainty of less than 1
There are several ways to derive the Hubble constant. Edwin Hubble observed the Doppler shift of retreating fog – these are the changes in the wavelength of light as the object moves farther away, but in the decades since then our methods have refined.
Calculations often use standard candles, such as Cepheid stars, whose known luminosity enables accurate distance calculations – and they have delivered fairly constant results faster than the Planck data.
Last year, for example, a Cepheid variable calc The calculation of the Hubble constant gave an expansion rate of 73.5 kilometers per second per megaparse second.
This measurement reduced the likelihood that the results would be incorrect at one in 5,000. Now we have a new result that restricts it even further.
Using a new Hubble Space Telescope method, an astronomical team calculated the absolute brightness of 70 Cepheid variables in the Large Magellanic Cloud more accurately than ever before.
With this data, they have derived a new Hubble constant: 74.03 kilometers per second per megaparse second.
That's about 9 percent faster than estimates based on Planck data. And the chance that the discrepancy is a coincidence or a mistake is now only one in 100,000.
"The Hubble tension between the early and late Universe is perhaps the most exciting development in cosmology in decades," said astrophysicist Adam Riess of the Space Telescope Science Institute (STScI) and Johns Hopkins University.
"This mismatch has grown and reached a point that really can not be dismissed as accidental, and this inequality could not be coincidentally plausible."
Which means that there is something out there we missed. As was derived last year from a study to derive the Hubble constant from black holes, acceleration could be the result of an increase in dark energy density.
It is believed that this mysterious form of energy accounts for about 70 percent of the matter-energy density of the universe and is currently the most accepted explanation for accelerating the growth of the universe.
Or it could be that dark matter interacts more with normal matter than astronomers did.
It could also mean that the result can not be explained by today's physics. So it could be a shiny new, strange physics required.
"These are not just two experiments that do not match," said Riess.
"We measure something fundamentally different, one is the measure of how fast the universe is expanding today, as we see it: the other is a prediction based on the physics of the early Universe and on measurements of how fast it should expand.
"If these values do not match, there is a very high probability that we are missing something in the cosmological model that connects the two eras.
The team's research has been accepted for publication in The Astrophysical Journal and is available on arXiv.