American Scientist – May-June 2021
English | 66 pages | pdf | 13.54 MB
Welcome at American Scientist Magazine VOLUME 109, NUMBER 3, 2021
Zoom out to the level of the whole universe, if you can imagine that. Looking at the whole thing at once, you might notice that there’s a lot that you actually cannot see. We can observe this same quandary at smaller scales: Stars in galactic systems rotate as if much more mass is present than the stars could contain. So where is this mass? This mysterious stuff is what astrophysicists call dark matter, but as University of New Hampshire theoretical physicist Chanda Prescod-Weinstein points out in our cover feature (“Enter the Axion,” pages 158–165), that moniker is really a misnomer. As she says, we can see light bouncing off dark objects, but so-called dark matter doesn’t interact with electromagnetic radiation at all. It’s more hidden to us than if it were simply dark.
So how do we go about getting data about something that we can’t image with any known methods? What could dark matter be made of? There are a number of theories, but in her article, Prescod-Weinstein discusses a promising theoretical particle called the axion, and a number of experiments that are aimed at nding evidence of its existence.
There are hidden phenomena in nature at all scales. Let’s zoom in now from the whole universe to our own planet. We can see the surface of it, but the interior is more mysterious. What’s happening in its roiling depths, and does that activity shape the surface—or does the surface shape the interior? In “The Chicken, the Egg, and Plate Tectonics” (pages 166–173), geodynamicist Nicolas Coltice of École Normale Supérieure in Paris describes a decade of effort to create models of the Earth’s interior that are as accurate as climate models (one example showing the surface and interior convection is at right). His research shows how the dynamic activity of Earth’s interior can alter the ways that rocks themselves behave and move on the surface of ourplanet, hundreds or thousands of kilometers away. Zoom in again, this time to the scale of our
genetic material inside our cells. There’s a lot going on in our DNA as it forms RNA, which then forms proteins that our bodies need to function. But there’s quite of a lot of DNA that doesn’t seem to do much at rst glance, which has been labeled junk DNA. Why would such long stretches of seemingly useless code stick around? It may not be surprising to nd out that it’s there because it’s not so useless after all. In “Turning Junk into Us: How Genes Are Born” (pages 174–181), Emily Mortola and Manyuan Long of the University of Chicago describe their extensive research aimed at seeing beyond the assumptions and guring out the process through which these stretches of nonsense DNA start evolving and eventually begin producing functional proteins.
Throughout this American Scientist Magazine issue, there are other stories of exploration leading to unexpected discoveries, from the rst isolation of nucleic acids, to artistic depictions of electrons, to serendipitous patterns of crystal growth on organic objects, to a new mission to move an asteroid. We hope all these accounts inspire you to search for new ways of seeing—or sensing by other means—the workings of everything around us. —Fenella Saunders (@FenellaSaunders)
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