Science & Technology

Half of Your Body's Atoms Come from Across the Universe

A long time ago, in galaxies far, far away ... your atoms were born. In a first-of-its-kind analysis, astrophysicists have found that half of the Milky Way's matter — you included — came from galaxies beyond our own. Cue the identity crisis.

Related Video: You Are Star Stuff

They Slip Away Across the Universe

"We are a way for the universe to know itself. Some part of our being knows this is where we came from. We long to return. And we can, because the cosmos is also within us. We're made of star stuff," Carl Sagan famously said in an episode of "Cosmos." Make that extragalactic star stuff, Carl.

In a study published in July 2017 by the Monthly Notices of the Royal Astronomical Society, Northwestern University astrophysicists have discovered that, contrary to previous belief, up to half of the matter in the Milky Way may come from distant galaxies. That includes half of the stuff that makes up you, your dog, Mount Everest, spaghetti squash, etc. We're just semblances of alien goo all here for a good time, ya know? Researchers reached this conclusion after the equivalent of several million hours of continuous supercomputer simulations. Easy enough.

Home Sweet Intergalactic Home

These simulations uncovered a major and unexpected new explanation for how galaxies, including our own, got all their matter: intergalactic transfer. This newly identified phenomenon basically goes down like this: Supernova explosions blast out huge gusts of gas. The ejected gas acts as powerful galactic winds that carry atoms from the exploded supernovae across the universe into different galaxies. Ta-da! Behold, the extragalactic atom soup we call the Milky Way. But it sure wasn't a quick process. Because galaxies are so, so spread out, all of our star stuff traveled huge distances over billions of years to get here. Damn, all that work to become that fingernail you just clipped off.

"Given how much of the matter out of which we formed may have come from other galaxies, we could consider ourselves space travelers or extragalactic immigrants," said Daniel Anglés-Alcázar, a postdoctoral fellow who led the study in Northwestern's astrophysics center, CIERA (Center for Interdisciplinary Exploration and Research in Astrophysics). "It is likely that much of the Milky Way's matter was in other galaxies before it was kicked out by a powerful wind, traveled across intergalactic space and eventually found its new home in the Milky Way." Bet you'll never look at yourself in the mirror the same way again.

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If thinking about your place in the universe is awe-inspiring, you should definitely check out Carl Sagan's classic bestseller, "Cosmos." We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Joanie Faletto July 30, 2017

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