Are black holes really the universe’s ultimate enigma, or is there something even stranger out there? Enter gravastars—the “evil twin” of black holes and a cosmic riddle that could redefine our understanding of reality.

Imagine a cosmic soap bubble: a thin, unbreakable shell forged in the furnace of a collapsing star, trapping pure energy in a core so dense it becomes a kind of “super-dense nothingness.” Gravastars are as massive as black holes, as cold as the edge of the universe, and just as invisible—yet they might be the key to answering some of physics’ biggest questions.

From their violent births in supernovae to their potential as the source of mysterious gravitational echoes, gravastars challenge everything we think we know. Are they real celestial objects or elegant mathematical speculation? Watch as Kurzgesagt delves into the science and theory behind these mind-bending entities, explaining why they might offer a solution to black holes’ most frustrating problems—like breaking physics.

Think you know why rainbows are curved? Well, it’s time to challenge that assumption! In this video, Veritasium takes us on a dive into the true science behind rainbows, and trust us, it’s far more complex (and exciting) than you might have imagined.

Why don’t we see rainbows when looking toward the sun? Why does the sky above a rainbow look darker? And what’s the connection between rainbows and Nobel Prizes? The video will give you an explanation that goes way beyond the usual oversimplified versions. From raindrops to the sun’s rays, and even the unique perspectives of a single raindrop, this video breaks down the process with awesome demonstrations and animations that make the science behind rainbows beautifully clear.

Get ready to see rainbows in a whole new light!