Gravitational Lens Measure The Hubble Constant

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An independent measurement of the Hubble Constant using three lensing quasars with the adaptive optics of the Keck Observatory confirmed that cosmology has a problem. Everything seems to suggest that the Hubble Constant is changing as the universe is older. And just so it even more “fun” it seems to be changing non-linearly.

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Image by Free-Photos from Pixabay

When the fact that the Universe is expanding came to light and more so that the expansion is speeding up it was a shock for many. This led to the creation of the concept of dark energy. Since then, the Hubble Constant – or the speed of the Universe expanding has been a highly discussed thing. Especially since different measurements of the constant are obviously different.

Now Geoff Chen and his colleagues from the University of California, Davis decided to take a look at the matter. And their results sure caught a lot of attention. Though, this is partially because the press release had a misleading title which indicated that the results were cosmology-breaking as from the title it seemed the Universe is expanding even faster. But that is not true.

The researchers used a new way of measuring the Hubble Constant that uses adaptive optics of terrestrial observatories. Chen and his team used the Hubble Space Telescope and in conjunction the adaptive optics of the Near-Infrared Camera 2nd generation (NIRC2) of the Keck II telescope in Hawaii. All this so they could use three gravitational lenses in quasar systems – PG1115+ 080, HE0435-1223, and RXJ1131-1231.

The authors were very careful to avoid any influencing of the results. During the data processing, they kept as much distance as possible and they worked blindly to avoid as many possible sources of errors as they could. This was done to prevent them from skewing the results towards expected results.

In the end, Chen and his team came to the conclusion which combines data from all the three gravitational lenses, terrestrial adaptive optics, and from the Hubble Telescope. They say the Hubble Constant is 76.8 +-2.6 kmpspMpc (kilometer per second per megaparsec). If you wonder, one megaparsec is roughly three million light-years.

I have said that these results are not the reason for a crisis in cosmology. And that is true. Because the crisis stems from the fact that measurements of the Hubble Constant are different based on the age of the Universe. If we measure the Hubble Constant on a near object – older universe versus an object further away from us – younger universe we get very differing measurements. Either we are making some mistakes during measuring or our standard cosmological model has a fatal flaw somewhere.

At the moment, it seems that our Universe was expanding very rapidly right after it came to be. Then the expansion slowed down – maybe because of the gravitational effects of dark matter and normal matter. And now the Universe seems to be getting quicker with its expansion possibly being fueled by the mysterious dark energy.

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