As if the universe is not vast enough as it already is, scientists are now saying that the space outside our world is still expanding at a faster rate than what was originally thought.

Researchers at the Space Telescope Science Institute (STScI) and the Johns Hopkins University in Maryland have discovered that the universe is growing about 5 to 9 percent faster compared with initial estimates made by astronomers.

Adam Riess, an astrophysicist from the STScI and leader of the study, explained that this finding provides a vital clue that could help scientists figure out the mystery of the universe, which is believed to be made up mostly of dark matter, dark energy and dark radiation.

Measuring The Universe

To find out more about the expansion of the universe, Riess and his colleagues examined several Type Ia supernovas and Cepheid stars using the Hubble Space Telescope. Scientists use these two groups of celestial bodies as a form of "yardsticks" to allow them to measure the distances between objects across the universe.

The pulse rates of Cepheid stars are connected to their true brightness, while Type Ia supernovas, which are usually formed following the death of a massive star, are known to have a consistent luminosity to them.

The researchers used these two factors to find out how far the supernovas are. They then compared these points to data regarding the expansion of the universe, which was determined by measuring the distance that light from other galaxies has to travel while moving away from Earth. This allowed the team to figure out how fast the universe was growing, a value that is referred to as the Hubble constant.

According to Riess and his team's calculations, the universe's Hubble constant is currently at 45.5 miles per second per megaparsec, where the value of 1 megaparsec is about 3.26 million light-years. The researchers estimate that at this rate, the distance between celestial objects in the universe could double in the next 9.8 billion years.

This figure is about 5 to 9 percent higher compared with earlier Hubble constant estimates. Previous readings were made by measuring radiation from the universe's cosmic microwave background, which is produced by the remaining light from the Big Bang some 13.8 billion years in the past.

The researchers said this discrepancy in readings could be caused by two factors. The first one is that the dark energy that is likely powering the rapid expansion of the universe could be stronger than what scientists initially thought.

The second possible reason is that the phenomenon could be influenced by dark radiation, which consists of the ultrafast subatomic particles that were left over following the Big Bang event.

The findings of the STScI and the Johns Hopkins University study are featured in the Astrophysical Journal.

Photo: Nigel Howe | Flickr 

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