The expansion rate of the universe, also called the expansion constant Hubble represents one of the essential parameters to understand how it evolves and what the final fate of the cosmos will be.
However, there is a persistent discrepancy known as “Hubble voltage” between the value of this constant measured by various independent distance indicators and the value predicted from the residual radiation of the Big Bang.
What was the confirmation that NASA received from the James Webb Telescope?
Before the Hubble Telescope came into existence 1990 the uncertainty in the rate of Expansion of the universe was so large that astronomers weren’t sure they could determine whether the universe had expanded over a period of 10 billion or 20 billion years.
This was because a faster expansion rate would have suggested a younger age of the universe, while a slower expansion rate would have suggested an older age of the universe.
The Hubble Telescope has a resolution in the visible wavelength range Superior comparable to that of any terrestrial telescope thanks to its position above the distorting effects of Earth’s atmosphere.
This allows it to recognize individual Cepheid variable stars which, due to their exceptional luminosity, have been providing extremely accurate distance measurements for over a century.
You can find these stars below more than a hundred million light years removed and allow measurement of the time period over which they change brightness.
During the telescope’s first year of operation James Webb Observations were carried out Cepheids previously discovered by Hubble. These observations were made in two phases during the so-called “cosmic distance ladder“, which represents a set of methods for measuring distances to increasingly distant objects in the universe.
Webb Telescope measurements have significantly reduced interference in Cepheid measurements, largely due to the following high resolution of the observatory in the near infrared wavelength range.
Thanks to the observation of more than 320 Cepheids, previous measurements of the space telescope were confirmed Hubble They were accurate, but more prone to interference.
What is the difference between NASA’s Hubble and James Webb telescopes?
The ability to obtain sharp images red light through the space telescope Hubble is limited compared to its capacity blue light This causes the light from Cepheid stars to overlap with other stars in their field of view.
However, the space telescope James Webb It has excellent ability to observe clearly in the infrared range. This is possible thanks to its wide mirror and highly sensitive optics easily separate the emitted light by keeping the Cepheids away from the light of nearby stars and thus minimizing interference,” he explained Adam Riess (from John Hopkins University, which led the new research with Webb).
