Universe expanding up to 9pc faster than we once thought

3 Jun 2016

Hubble Monitors Supernova In Nearby Galaxy M82. Image via NASA, ESA, A. Goobar (Stockholm University), and the Hubble Heritage Team (STScI/AURA)

Using NASA’s Hubble Space Telescope, a team of astronomers has discovered that the universe is expanding much faster than we once thought, and it could be due to the weirdness of dark matter.

In the field of cosmology and the study of the universe, there are three very contrasting opinions on what the future holds for it and, more specifically, whether it is contracting or expanding towards oblivion.

While some believe it will end with the ‘Big Crunch’, others believe it’s not expanding at all, while there’s a sizeable number who would agree with evidence that shows the distance between celestial objects is growing, suggesting an expanding universe.

Now, a team of astronomers using NASA’s Hubble Telescope believe they can show not only that the universe is expanding, but that it’s expanding 9pc faster than we thought.

The team from the Space Telescope Science Institute was able to accurately measure the current expansion rate, reducing the uncertainty to only 2.4pc, by looking for galaxies containing both Cepheid stars and Type Ia supernovae.

UGC 9391

Compass and Scale Image for UGC 9391 used to measure the vast distances. Image via NASA, ESA, and L Frattare (STScI)

A yardstick for the universe

Both are commonly used yardsticks to measure distance in astronomy, as the rate at which Cephid stars pulsate in their true brightness compared with what we see on Earth is an accurate measurement of distance.

Similarly, Type Ia supernovae are exploding stars that flare with the same brightness and are brilliant enough to be seen from relatively longer distances.

So, by measuring about 2,400 Cepheid stars in 19 galaxies and comparing the observed brightness of both types of stars, the team could accurately measure their true brightness and calculate distances to roughly 300 Type Ia supernovae in far-flung galaxies.

These distances could then be compared with the stretching of light from receding galaxies, all of which has found that the revised expansion rate is now 73.2km per second per megaparsec.

Universe expansion

The three steps astronomers used to measure the universe’s expansion rate to an unprecedented accuracy, reducing the total uncertainty to 2.4pc. Image via NASA, ESA, A. Feild (STScI), and A. Riess (STScI/JHU)

With a megaparsec equating to 3.26m light years, it is now envisioned that the distance between cosmic objects will double in just under 10bn years’ time.

So what’s causing this rapid expansion?

While there is no definitive answer, one potential cause could be some unknown and strange characteristic found within mysterious dark matter, or, even, that Albert Einstein’s General Theory of Relativity might not be as complete as we once thought.

“This surprising finding may be an important clue to understanding those mysterious parts of the universe that make up 95pc of everything and don’t emit light, such as dark energy, dark matter, and dark radiation,” said study leader, Adam Reiss.

While the reduction of uncertainty to just 2.4pc is a major achievement for accurately measuring the distances of the universe, the team now wants to reduce this to just 1pc, which could be achieved using the newer generations of telescopes.

Colm Gorey was a senior journalist with Silicon Republic