babyproofing
Explanation
The Joke
A scientist excitedly announces that dark matter, long theorized to be something that does not interact with normal matter, has been found to have a way to interact with "the fabric of spacetime." The scene then cuts to a baby crawling toward what appears to be a tear or rip in the fabric of spacetime itself. The parents scream "NO BABY NO!" and "RUN! IT'S TOO LATE!" as the baby gleefully chews on or tears apart the fabric of spacetime, resulting in a catastrophic explosion of reality rendered as colorful chaos and screaming.
The comic takes the phrase "fabric of spacetime" -- a common physics metaphor -- completely literally. If spacetime has a fabric, then a baby can grab it, chew on it, and destroy it, just as babies are notorious for grabbing and destroying every physical object within reach.
The Humor
The humor operates on multiple levels. First, there is the literalization of the physics metaphor: treating "the fabric of spacetime" as an actual piece of cloth that can be torn. Second, there is the universal parenting experience of babies destroying everything they touch, elevated to a cosmic scale. The frantic parental panic -- "NO BABY NO!" -- is exactly the same whether a baby is reaching for a power outlet or unraveling the fundamental structure of reality. The comic suggests that if physicists ever do find a way for matter to interact with spacetime's fabric, the first thing we should do is babyproof it.
References
Dark matter is a hypothetical form of matter that is thought to account for approximately 27% of the mass-energy of the universe. It does not interact with the electromagnetic force, making it invisible and detectable only through its gravitational effects. The joke plays on ongoing efforts in particle physics to find direct interactions between dark matter and ordinary matter.