Thanks to MyHeritage for sponsoring this video! Click my link or scan the QR code, and use the coupon code physics to get your DNA kit for just $29 — plus a 30-day free trial! Electrons aren’t supposed to exist inside the nucleus — but quantum mechanics reveals a strange truth: sometimes they do. In this video, we explore what the wavefunction and Heisenberg’s uncertainty principle really say about electrons in nuclear space. We calculate the tiny probability of finding an electron inside the nucleus, compare hydrogen with heavier atoms like iodine and gold, and uncover why this fleeting overlap matters for real processes. Finally, we tackle the classic question of beta decay: are electrons trapped in the nucleus waiting to escape, or are they created in the moment of decay?