Putting the special theory of relativity into practice by counting galaxies

Putting the special theory of relativity into practice by counting galaxies

This image is from September 2003-January 2004 composite images taken by the NASA/ESA Hubble Space Telescope showing nearly 10,000 galaxies in the deepest visible-light image of the universe, cut across billions of light years. Image Credit: NASA, ESA, S. Beckwith (STScI), HUDF Team

Scientists who study the universe have a favorite philosophy known as the “Badness Principle,” which, in essence, suggests that there is nothing really special about the Earth, the Sun, or the Milky Way compared to the rest of the universe.

Now, new research from CU Boulder adds further evidence to the mean issue: galaxies are, on average, at rest with respect to early universe. Jeremy Darling, professor of astrophysics at the University of Colorado Boulder, recently published this new cosmic discovery in Astrophysical Journal Letters.

“What this research tells us is that we have a funny movement, but this funny movement is consistent with everything we know about Universe“There’s nothing special going on here,” Darling said. “We’re not special as a galaxy or as observers.”

Nearly 35 years ago, researchers discovered the cosmic microwave background, which is electromagnetic radiation What remains of the formation of the universe during the Big Bang. The cosmic microwave background appears to be warmer in the direction of our motion and cooler further in the direction of our motion.

From this glow of the early universe, scientists can conclude that the sun – and the Earth that orbits it – is moving in a certain direction, at a certain speed. The researchers found that our inferred velocity is a fraction of a percentage of the speed of light — small but not zero.

Scientists can test this conclusion independently by calculating galaxies visible from the Earth or increase its brightness. They can do it thanks to Albert Einstein in 1905 special theory of relativity, which explains how speed affects time and space. In this app, anyone on Earth who looks at the universe in one direction – the same direction the Sun and Earth move – should see brighter, bluer, more focused galaxies. Likewise, by looking the other way, a person should see galaxies that are darker, red, and farther apart.

But when researchers have attempted to count galaxies in recent years — a process that is difficult to perform with precision — they came up with numbers that indicate the Sun is moving much faster than previously thought, which is inconsistent with standard cosmology.

“It’s hard to count the number of galaxies in the entire sky, you’re usually stuck with one hemisphere or less,” Darling said. Moreover, our galaxy is getting in the way. They contain dust that will make you find fewer galaxies and make them look fainter the closer you get to our galaxy.

Darling was fascinated and confused by this cosmic mystery, so he decided to research himself. He also knew there were two recently released surveys that could help improve the accuracy of galactic counts — and shed light on the speed conundrum: one called the New Mexico Very Large Array of the Sky (VLASS) survey, and the other called the Rapid Australian Square Kilometer Pathfinder Continuum Survey (RACS). ) in Australia.

Together, these surveys allowed Darling to study the entire sky by patching together views of the northern and southern hemispheres. Most importantly, the new surveys were also used radio waveswhich made it easier to “see” through the dust of the Milky Way, thereby improving the view of the universe.

When Darling analyzed a file SurveysHe found that the number and brightness of galaxies are in perfect agreement with the speed that the researchers had previously inferred from the cosmic microwave background.

“We find a bright trend and a faint trend – we find a direction where there are more galaxies and a direction where there are fewer galaxies,” he said. “The big difference is that it lines up with the early universe of cosmic microwave background And it has the right speed. Our cosmology is good.”

Because Darling’s findings differ from previous findings, his paper will likely prompt various follow-up studies to confirm or contest his findings.

But in addition to pushing the field of cosmology forward, the results are a good real-world example of Einstein’s special theory of relativity — and they show how researchers are still putting the theory into practice, more than 100 years after the famous physicist first proposed it. .

“I like the idea that this basic principle that Einstein told us about a long time ago is something you can see,” Darling said. “It’s really an esoteric thing and it looks very strange, but if you go out and go back in the galaxies, you can see this neat effect. It’s not as esoteric or weird as you might think.”

Celebrating Hubble’s 32nd birthday with a group of galaxies

more information:
Jeremy Darling, The Universe is getting brighter in the direction of our motion: The numbers and flow of galaxies are consistent with the CMB dipole, Astrophysical Journal Letters (2022). DOI: 10.3847 / 2041-8213 / ac6f08

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