NASA’s Webb telescope confirms Hubble’s baffling observations about Universe’s expansion rate

Physicists used NASA’s James Webb Space Telescope to confirm Hubble’s measurements that find the current rate of expansion of the universe is faster than expected. However, scientists are still trying to connect the dots between the beginning of the universe to present day to understand what is causing the universe expansion to accelerate.

NASA’s James Webb Space Telescope has confirmed Hubble Space Telescope’s measurements that find the current rate of expansion of the universe is faster than expected. Still, scientists don't understand what is causing the universe's expansion to accelerate.

Physicists have been trying to understand the "Hubble tension," which refers to the questions surrounding Hubble's observations over 30 years that indicate the universe is expanding faster than expected based on our understanding of the universe. 

Many questions remain about why the universe is expanding. The mystery phenomenon is known to cosmologists as "dark energy." 

How to measure the universe

According to NASA, astronomers use objects known as Cepheid variable stars to measure relative cosmic distances. These pulsating stars are used as universal markers because they go through cycles of dips and peaks in brightness, which help astronomers determine the distance to the star. They can also determine distances from our galaxy to other galaxies.


The SH0ES (Supernova H0 for the Equation of State of Dark Energy) team, led by Nobel Prize physicist Adam Reiss, used Webb telescope observations of Cepheids also observed by Hubble to "check its homework," the space agency said.

The image above shows side-by-side photos of a Cepheid variable star taken by both telescopes, used to measure the universe's expansion rate. 

The initial Webb observations, fact-checking Hubble data, confirmed the first rungs of the "cosmic distance ladder" – the process of measuring nearby galaxies and then moving farther and farther away, also known as the "Hubble Constant."

"We’ve now spanned the whole range of what Hubble observed, and we can rule out a measurement error as the cause of the Hubble Tension with very high confidence," Riess said.

New Webb observations included five host galaxies with 1,000 Cepheids, including the farthest galaxy where Cepheids have been measured. Galaxy NGC 5468, pictured below, is 130 million light-years away.

"This spans the full range where we made measurements with Hubble. So, we've gone to the end of the second rung of the cosmic distance ladder," said Gagandeep Anand of the Space Telescope Science Institute.


NASA said scientists are seeking the missing pieces to link the beginning of the universe to the present day, which has yet to be observed.

In the coming years, two dark matter detectives could help reveal the cause of the universe's expansion.

European Space Agency's spacecraft Euclid, launched last year, will create a 3D map of the sky, viewing its evolution over 10 billion years. NASA is also launching the Nancy Grace Roman Space Telescope in 2027 to study the influence of dark energy and other mysteries of the universe.