phd
Explanation
The Joke
This is a crossover comic between SMBC and PhD Comics ("Piled Higher and Deeper" by Jorge Cham). The comic features characters from both strips discussing dark matter. A PhD Comics-style character explains the basics of dark matter to the SMBC characters: pop science sometimes wrongly implies dark matter is some exotic substance in space, but it is actually all around us. The center of our galaxy has a huge dark matter halo, and it extends out in every direction. The Earth is surrounded by dark matter, and our neighborhood is one of the few places in the galaxy that lacks the most common stuff in the universe.
The discussion continues with the PhD character explaining that the only thing we know about dark matter is that it really, really exists -- it interacts gravitationally but does not interact through electromagnetism, and it does not feel it has to explain itself to us. When one of the SMBC characters asks if they could get a piece of dark matter and use it as a Christmas ornament, the PhD character explains that it would not really work because dark matter just passes through everything. However, the dark matter itself has been passing through them the entire conversation.
The final panel has the PhD character suggesting "Remember, you could decorate your Christmas tree with dark matter -- like Winthorpe!" with a reference to making dark matter decorations.
The Humor
The comic works as both an educational piece and a comedy by taking the abstract concept of dark matter and making it relatable through everyday scenarios. The running gag is the contrast between how exotic and mysterious dark matter sounds versus how mundane its actual presence is -- it is literally everywhere, passing through us constantly, yet we cannot interact with it in any meaningful way. The joke about wanting to use it as a Christmas ornament captures the human impulse to make the cosmic tangible and decorative.
As a crossover between SMBC (known for science humor with a philosophical edge) and PhD Comics (known for academic life humor with science education), the comic plays to both audiences by combining accurate science communication with the comedic frustration of trying to explain something that is, by its very nature, invisible and intangible.
References
Dark matter is a hypothetical form of matter that is thought to account for approximately 27% of the mass-energy content of the universe. It does not interact with the electromagnetic force (meaning it does not absorb, reflect, or emit electromagnetic radiation) and is thus invisible. Its existence is inferred from gravitational effects on visible matter, gravitational lensing, and the structure of the cosmic microwave background. The dark matter halo mentioned in the comic refers to the roughly spherical distribution of dark matter that surrounds galaxies, including the Milky Way. PhD Comics ("Piled Higher and Deeper") is a newspaper and webcomic strip by Jorge Cham that follows the lives of graduate students, and is well known for its science education content.