Mirror universe model may be more than science fiction

Have scientists proven a mirror universe actually exists?

Star Trek was telling multiverse stories long before multiverse stories became cool. As early as the admittedly lackluster and generally incoherent first-season episode “The Alternative Factor,” the franchise has depicted myriad alternate dimensions and realities existing alongside our own. Indeed, given the discrepancies between Star Trek’s history and our own—I missed Khan ruling more than a quarter of the world in the 1990s; did you catch that?—its “prime” timeline might not even be our own!

Most famously, Star Trek introduced a “Mirror Universe” in the original series’ second-season episode “Mirror, Mirror.” One of four episodes scripted by Jerome Bixby, “Mirror, Mirror” sees Kirk, Uhura, Scotty, and McCoy accidentally beamed up to the I.S.S. Enterprise, a warship of the ruthless Terran Empire in a sinister parallel plane of existence.

This “Mirror Universe” (never called by that name in the episode itself) would reappear in several episodes of Star Trek: Deep Space Nine, a standout two-parter in the fourth season of Star Trek: Enterprise, and the first and third seasons of Star Trek: Discovery.

But now it seems some scientists have reason to think a “mirror universe” may not be strictly the stuff of science fiction. A serious research paper published in Physical Review Letters— “the world’s premier physics letter journal,” according to its website, “and the American Physical Society’s flagship publication”—posits a “mirror world” dark sector in the universe that may resolve long-standing cosmological mysteries.

A mirror universe could be influencing the rate of our universe’s expansion

I am not an astrophysicist, nor do I play one on TV. I haven’t read “Symmetry of Cosmological Observables, a Mirror World Dark Sector, and the Hubble Constant” by Francis-Yan Cyr-Racine, Fei Ge, and Lloyd Knox for myself. Even its abstract is challenging reading for me!

But as Brian Koberlein, who is an astrophysicist, writes for Universe Today (in a piece highlighted by The Debrief’s Christopher Plain), the paper proposes a cosmic invariance in “unitless parameters”—measured cosmological constants such as the rate at which the universe expands, that, when combined, “giv[e] you the same number no matter what units you use” to measure them—could result from “an underlying cosmic symmetry.” Koberlien writes that “if this invariance is real, it implies the existence of a mirror universe” that would “affect our universe through a faint gravitational pull.”

Even Koberlein’s explanation is pretty heady stuff. And these cosmological calculations don’t amount to proof positive that we all have scar-sporting, midriff-baring, goatee-wearing doppelgangers somewhere out there.

But it’s another pretty cool illustration of how the science fictional liberties Star Trek takes to tell great stories can often end up closer to science fact than viewers may initially think!