The most accurate astronomical electromagnetic test to date

credit: NASA

There is a disturbing and annoying problem with our understanding of the laws of nature that physicists have tried to explain for decades. It’s about electromagnetism, the law of the interaction of atoms and light, which explains everything from why you don’t fall to the ground to why the sky is blue.


our the theory Electromagnetism is arguably the best physical theory humans have ever come up with, but it has no answer as to why electromagnetism is as strong as it is. Only experiments can tell you the strength of electromagnetism, which is measured by a number called α (also known as alpha, or fine structure constant).

American physicist Richard Feynman, who helped develop the theory, called him “One of the greatest mysteries of physics,” he urged physicists to “stick that number on the wall and worry about it.”

In a research just published in Science, we decided to test whether α is the same in different places of our galaxy by studying stars that are nearly identical twins of our Sun. If α is different in different places, it can help us find the ultimate theory, not only of electromagnetism, but of all the laws of nature together – the “theory of everything”.

We want to break our favorite theory

Physicists really want one thing: a situation in which our current understanding of physics is collapsing. New physics. A signal that cannot be explained by current theories. Mark the theory of everything.

Sun Rainbow: Sunlight is scattered here in separate rows, each covering only a small range of colours, to reveal the many dark absorption streaks of atoms in the Sun’s atmosphere. Credit: NA Sharp/KPNO/NOIRLab/NSO/NSF/AURA, CC BY

To find it they can wait Deep in the earth in a gold mine Dark matter particles collide with a special crystal. or they can Carefully maintain the best atomic clocks in the world For years to see if they were referring to slightly different weather. or smash protons together in (roughly) light’s speed In the episode 27 km from Large Hadron Collider.

The problem is that it’s hard to know where to look. Our current theories cannot guide us.

Of course, we are researching in laboratories on the ground, where it is easy to research with precision and accuracy. But it is somewhat similar Drunk is just looking for his lost keys under a lamppost Whereas in reality he could have lost them across the road somewhere in a dark corner.

The stars are awesome, but they are sometimes terribly similar

We decided to look beyond the earth, behind us solar system, to see if stars that are almost twins to our Sun produce the same colors as the rainbow. Atoms in a star’s atmosphere absorb some of the light that struggles with the outside of the nuclear furnaces in their cores.

Only certain colors are absorbed, leaving dark streaks in the rainbow. These absorbed colors are determined by α, so measuring the dark lines very carefully also allows us to measure α.

The hotter and cooler gas bubbles in the turbulent atmospheres of stars make it difficult to compare the absorption lines in stars to those observed in laboratory experiments. Credit: ONS/AURA/NSF, CC BY

The problem is that the atmospheres of stars move—boiling, spinning, spinning, and rotting—and that stirs the streaks. The offsets spoil any comparison with the same lines in laboratories on Earth, and therefore any chance of measuring α. The stars seem to be horrible places to test electromagnetism.

But we wondered: If you find very similar stars — twins to each other — maybe their dark, absorbing colors are similar, too. So instead of comparing stars to laboratories on Earth, we’ve been comparing our Sun’s twins to each other.

New test with solar twins

Our team of students, postdocs and senior researchers at Swinburne University of Technology and the University of New South Wales measured the spacing between pairs of absorption lines in our Sun and 16 “solar twins” – stars almost indistinguishable from our Sun.

Rainbows of these stars have been observed on 3.6 meter telescope for the European Southern Observatory (ESO) in Chile. Although it is not the largest telescope in the world, the light it collects probably travels to the most controlled and understood spectrogram: HARPS. This separates the light into its colors, revealing the detailed pattern of the dark lines.

HARPS spends most of its time observing sun-like stars in search of planets. Practically speaking, this provided a trove of exactly the data we needed.

ESO’s 3.6-meter telescope in Chile spends much of its time observing sun-like stars to search for planets with its extremely accurate spectrometer, HARPS. Credit: Iztok Bončina / ESO, CC BY

From these remarkable spectra, we showed that α was the same in all 17 solar twins with astonishing accuracy: only 50 parts per billion. It’s like comparing your height to the circumference of the Earth. It is the most accurate astronomical test for α ever performed.

Unfortunately, our new measurements did not break our favorite theory. but the stars The ones we studied are all relatively close, only 160 light-years away.

And yet?

We recently identified new solar twins much further away, about halfway to the center of our galaxy, the Milky Way.

In this region, there should be a much higher concentration of dark matter, an elusive substance that astronomers say lurks throughout the galaxy and beyond. Like α, we know very little about dark matter, and Some theoretical physicists It suggests that the inner parts of our galaxy may just be the dark corner where we should look for connections between these two “dreaded puzzles of physics”.

If we can observe these distant suns with the largest optical telescopes, we may find the keys to the universe.

More information:
Michael T. Murphy et al., Limit on the constant variations of the fine structure from the spectra of stars close to the Sun, Science (2022). DOI: 10.1126 / science.abi9232

This article has been republished from dialogue Under Creative Commons License. Read it original article.dialogue

quotes: “One of Physics’ Greatest Mysteries”: The Most Accurate Astronomical Test of Electromagnetism Yet (November 11, 2022) Retrieved November 11, 2022 from https://phys.org/news/2022- 11-most-damn-mysteries-precise-physics .html

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