Cosmic Latte and Other Oddities: The Universe's Color, NYC Rats That 'Talk', and Heritable Traits Beyond DNA

From Popular Science’s podcast: three odd-but-true science stories that show how research can surprise (and amuse) us.

What color is the universe?

In 2002, astronomers who combined light from more than 200,000 galaxies tried to answer a playful question: if you trapped every photon that reaches Earth in a box and viewed it in a dark room, what single color would you see? Their initial calculation produced a turquoise-green shade—until color scientist Mark Fairchild noticed a critical error.

The team had used free software calibrated to the wrong white point, effectively treating the viewer as if they stood in a room lit by neon-red light. After fixing the calibration, the combined light shifted to a faint pinkish-beige—so close to white that the researchers argued most people would hardly notice the difference. The group held a public naming contest (this was 2002), with entries such as "Big Bang Buff," "Cosmic Cream," and the winning name: "Cosmic Latte." The name nods to milk (latte) and to Galileo’s Italian roots as well as the Milky Way.

Some objected that most of the universe is empty space and therefore looks black. The researchers responded that regions with no detectable light contain no visible information for this exercise, so naming the whole cosmos "black" would miss the point of characterizing the aggregate light we actually observe.

Rats that behave like New Yorkers

Science communicator Tom Lum dives into new research on brown rats living in New York City. Studying animal behavior in a noisy, crowded metropolis is difficult: how do you extract meaningful signals from constant background noise?

Researchers applied computational ecology—combining thermal imaging, ultrasonic microphones, and AI models—to sift through long recordings and isolate rat vocalizations. The results were unexpectedly familiar: rats vocalize frequently, both alone and in groups; juveniles explore together and move more slowly (evoking college freshmen), while solitary rats move faster. During one recording, two rats raised their vocal volume when an ambulance siren passed, apparently trying to be heard over the noise.

These findings suggest city rats have adapted socially and acoustically to urban life. The study also illustrates a constructive use for AI: rigorous, reproducible analysis of complex ecological data rather than hype or misinformation. Find more of Tom Lum’s work on his website; he’s also hosting a science game show, Our Findings Show, at Caveat on November 11, with streaming tickets available.

Inherited quirks that challenge DNA-only thinking

Classic and recent experiments reveal that heredity is sometimes stranger than the simple DNA-only picture presented in many textbooks. In the 1960s, Baltimore biologist Tracy Sonneborn performed manipulations on paramecia—single-celled organisms covered in cilia. He removed a patch of cortex, rotated it 180 degrees, and reattached it. Surprisingly, offspring of these altered cells sometimes inherited the flipped cilia orientation for many generations despite no change in DNA sequence. Other labs reproduced similar effects.

More modern work adds to the complexity. For example, some studies in worms show that exposure to certain pathogens or stressors can lead to transmission of immune-related molecules or epigenetic marks to descendants for dozens of generations. These phenomena don't overturn genetics, but they show that non-DNA mechanisms—cellular structure, epigenetic marks, and small RNAs or proteins—can influence inheritance in ways that deserve further study. The result is a richer, more nuanced view of heredity that complements Mendelian genetics rather than replacing it.

Why it matters: Each of these stories—cosmic color, urban animal behavior, and non-DNA inheritance—illustrates how asking a strange question, using new tools, or revisiting old experiments can reveal surprising layers of reality.