Cosmological Observations: Universe Is Expanding Too Fast

A new study based on highly detailed observations taken using the Hubble Space Telescope confirms that the universe is expanding very fast.

According to the study, which was tackled in a Live Science recent report, it is in the early years of the universe, right after the Big Bang, when everything blasted away from everything else. The light caused from that blast can still be visible as it takes billions of years to reach our telescopes. Theoretically, it is possible to measure how fast things were moving in those faraway spots based on that speed, and therefore, how fast the universe should be expanding today can be calculated.

But when astronomers have tried to directly measure how fast the universe is expanding today — a more difficult task, because everything is farther apart now — things seem to be moving faster than those calculations would predict. The paper appears to confirm that everything is moving about 9 percent too fast.

Earlier observations of that increased speed still had a 1 in 3,000 chance that astronomers were wrong, which is considered pretty high for an astrophysics result. This new paper published at April 25 issue of The Astrophysical Journal Letters, improves astronomers’ confidence, with just a 1 in 100,000 chance of being based on an observational error.

“This mismatch has been growing and has now reached a point that is really impossible to dismiss as a fluke. This is not what we expected,” lead author Adam Riess, a Johns Hopkins University Nobel laureate and astrophysicist, said in a statement.

The researchers relied on the same tool that astronomer Edwin Hubble used to show that the universe was expanding back in 1929: a class of pulsing stars called cepheids.

Cepheids, the astronomer Henrietta S. Leavitt had shown in a 1908 paper in the journal Annals of the Harvard College Observatory, pulse in direct proportion to their brightness. That means that astronomers can figure out exactly how bright a cepheid should be based on how fast it’s pulsing. Then, by seeing how dim it looks from Earth, they can tell how much light it’s lost along the way, and thus how far away it is.

To measure the rate of the universe’s expansion, astronomers check the distance to cepheids in nearby and faraway galaxies. But that’s usually a slow task to do precisely, with the Hubble able to precisely measure just one distant cepheid at a time. The researchers developed a method to allow the space telescope to “drift” as it images the stars, imaging more than one at the same time and drastically increasing the precision of their overall distance measurement.

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