ftl
Explanation
The Joke
Humans encounter aliens and ask how they got here, since interstellar travel requires crossing vast distances. The aliens explain they used relativity -- specifically, they mastered faster-than-light (FTL) travel via a "light tunnel." The humans ask about the experience of relativity-breaking travel, expecting something profound about the nature of spacetime. The aliens respond that the experience of breaking relativity is essentially unlimited access to high-fidelity pornography from across the universe, because FTL communication means access to every civilization's internet. The humans' reaction is simply "Amen."
The comic sets up a classic first-contact science fiction scenario and subverts it. Instead of the aliens sharing profound cosmic wisdom or advanced scientific knowledge, the practical upshot of their technological achievement is the same thing that drives a huge portion of human internet usage: pornography.
The Humor
The humor comes from deflating the grandeur of interstellar travel and first contact with aliens down to the most base human (and apparently universal) motivation. It plays on the well-known observation that pornography has been a major driver of virtually every communication technology humans have developed -- from the printing press to VHS to the internet. The comic suggests this is not just a human phenomenon but a universal constant across all intelligent species. The humans' immediate, reverent agreement ("Amen") makes it even funnier, as it suggests they completely understand and share this priority.
References
The comic references Einstein's theory of special relativity and the speed of light as a universal speed limit, which is a fundamental concept in physics that makes interstellar travel so challenging in reality. The idea of FTL travel is a staple of science fiction.