It is already a widely accepted concept that the universe is continually expanding, expanding outward and causing the space between galaxies to keep growing and growing. The question is, how fast does the cosmos grow? About 9% faster than expected, according to new research.
A mismatch between expansion rates
The latest measurement of the expansion rate of the universe has confirmed with more certainty than ever that we have a real dilemma on our hands. Once again, the result has shown that the universe is expanding much faster than it should based on conditions just after the Big Bang – 380,000 years after the Big Bang. It is what we know as the Hubble constant, and it has been incredibly difficult to pin down.
The old predictions were based on measurements of the early universe after the Big Bang using the European Space Agency’s Planck satellite.
Now the calculations often involve the use of standard candles, such as Cepheid variable stars, whose known luminosity allows for precise distance calculations, and they have yielded results significantly faster than Planck data.
Measuring the Hubble constant
There are several ways to derive the Hubble constant. Edwin Hubble observed the Doppler effect of retreating nebulae, that is, the changes in the wavelength of light as the object moves away. But, over the decades, our methods have been refined.
Using a new method with the Hubble Space Telescope (DASH), a team of astronomers calculated the absolute brightness of 70 Cepheid variables in the Large Magellanic Cloud more accurately than ever. With this data, they have derived a new Hubble constant: 74.03 kilometers per second per megaparsec (one megaparsec is equivalent to about 3 million light years), with a margin of error of 1.9%.). This is about 9% faster than estimates based on Planck data. And the possibility that the discrepancy is a coincidence or an error has gone from 1 in 3,000 to 1 in 100,000.
“The Hubble tension between the early and later universe may be 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 been growing and has now reached a point where it is really impossible to dismiss it as a fluke . This disparity could not happen by chance.”
What have we missed?
Which means that there is something out there that we have missed. The acceleration could be the result of an increase in the density of dark energy. This mysterious form of energy is believed to make up about 70% of the matter-energy density of the universe, and is the current most widely accepted explanation for the acceleration of the growth of the cosmos.
Or it could be that dark matter is interacting more energetically with normal matter than astronomers have taken into account. But it could also mean that yeah the result can’t be explained according to current physics it might take some strange new physics to understand it better.
“These are not just two experiments at odds,” Riess said, referring to the already outdated Planck data with the new Hubble data . “We are measuring something fundamentally different. One is a 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 measurements of how fast it should expand.” “If these values do not agree, there is a high probability that we are missing something in the cosmological model that connects the two eras,” concludes the expert.
Referencia: “Large Magellanic Cloud Cepheid Standards Provide a 1% Foundation for the Determination of the Hubble Constant and Stronger Evidence for Physics Beyond LambdaCDM,” Adam G. Riess et al., 2019, Astrophysical Journal, arxiv.org/abs/1903.07603
Crédito imagen: NASA, ESA, Adam Riess, and Palomar Digitized Sky Survey
