The most accurate astronomical test of electromagnetism to date

'One of Physics' Greatest Damned Mysteries': Studying the Distant Sun in the Most Accurate Astronomical Test of Electron

credit: NASA

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

our theory The theory of electromagnetism is arguably the best physical theory man has ever made – 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 microstructure constant).

American physicist Richard Feynman, who helped come up with the theory, This is called “One of the greatest damned mysteries of physics,” he urged physicists to “put that number on their wall and worry about it.”

In a research just published in Sciences, we decided to test whether α is the same in different places within our galaxy by studying stars that are nearly identical twins of our Sun. If α is different in different places, it might help us find the ultimate theory, not just 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. Remarkable theory of everything.

'One of Physics' Greatest Damned Mysteries': Studying the Distant Sun in the Most Accurate Astronomical Test of Electron

Sun’s rainbow: Here sunlight is scattered 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 may wait Deep in the earth in a gold mine Dark matter particles collide with a special crystal. Or maybe Take care of the best atomic watches in the world For years to see if she tells us a slightly different time. or smash protons together in (roughly) light’s speed In the 27 km loop 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 Earth, where it is easier to research comprehensively and accurately. But this is somewhat similar to a file Drunk is just looking for his lost keys under the lamppost While in reality he might have lost them on the other side of 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 nearly identical twins to our Sun produce the same colors as the rainbow. The atoms in the stars’ atmosphere absorb some of the light battling out from the nuclear furnaces in their cores.

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

'One of Physics' Greatest Damned Mysteries': Studying the Distant Sun in the Most Accurate Astronomical Test of Electron

The hotter and colder gases that flow through the turbulent atmospheres of stars make it difficult to compare the absorption lines in stars to those seen in laboratory experiments. Credit: NSO/AURA/NSF, CC BY

The problem is that the shells of stars move — boil, spin, spin, burp — and that changes the lines. The shifts spoil any comparison with the same lines in laboratories on Earth, and thus 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 nearly indistinguishable from our Sun.

Rainbows of these stars have been observed on European Southern Observatory (ESO) telescope 3.6 meters long in Chile. Although it is not the largest telescope in the world, the light it collects is probably fed into the best controlled and understood spectrometer: 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. Indeed, this provided a trove of exactly the data we needed.

'One of Physics' Greatest Damned Mysteries': Studying the Distant Sun in the Most Accurate Astronomical Test of Electron

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 the seventeen solar twins with amazing accuracy: only 50 parts per billion. This is 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 We’ve all studied it relatively close, only up to 160 light-years away.

What’s Next?

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

In this region, there should be a much higher concentration of dark matter – an elusive substance that astronomers believe lurks throughout the galaxy and beyond. Like α, we know little about dark matter, and Some theoretical physicists We suggest that the inner parts of our galaxy may just be the dark corner that 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 to changes in the fine-structure constant from the spectra of nearby Sun-like stars, Sciences (2022). DOI: 10.1126 / science.abi9232

This article has been republished from Conversation Under a Creative Commons License. Read the original article.Conversation

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