Main Page

Welcome to the explain xkcd wiki!
We have an explanation for all 3269 xkcd comics, and only 46 (1%) are incomplete. Help us finish them!

Latest comic

Go to this comic explanation

Side Effect

|< < Prev #3261 (June 19, 2026)

Title text: Brace yourself--the chirp gets pretty weird.

|< < Prev Random Explanation

Explanation

This comic takes the concept of medication side-effects ad absurdum. The side effect of sensitivity to sun exposure described by Beret Guy is entirely precedented, however, sensitivity to gravitational waves is far less normal.^{[citation needed]} Due to the entirely normal first side effect, Ponytail initially misses the gravitational wave side effect. She is about to find out what that is about.

Gravitational waves, to oversimplify, are waves of distortion in spacetime caused by fast-moving gravitational objects such as black holes orbiting each other. They travel at the speed of light and can be measured by precise instruments (interferometers) which detect the ever-so-slight stretching and squishing caused by gravitational waves. As a side-effect of his medication, Beret Guy exhibits the stretching and squishing of a gravitational wave much stronger than normal, to the degree that it is visible to the naked eye. Beret Guy's hat also stretches and shrinks, indicating it could be a part of his body, which contradicts the idea from an earlier comic that it is stapled to his head. Alternatively, it may be part of the strange power the medicine makes him exhibit.

This is probably the most extreme example to date of Beret Guy being peculiarly sensitive to minuscule external forces. By way of comparison, the most sensitive current ground-based laser interferometer, LIGO, has light storage arms which are 4 km in length, and with strong gravitational waves, it experiences changes in the distance between the ends of the arms by at most roughly 10⁻¹⁸ meters, or 1 attometer. The relative change is thus about 2.5 × 10^-22. If Beret Guy is experiencing distortions of about a quarter of his height, the relative change is 0.25, larger than LIGO's by a factor of about 10²¹. However, rather than showing concern for his body rapidly changing shape, he instead enjoys the feeling, saying 'Whee' in the last panel.

"The chirp" described in the title text refers to gravitational waves during the end-stages of black hole collision, during which expansion and contraction of the waves increase in frequency to the point where they alternate extremely rapidly. When the gravitational wave is represented through sound, it does indeed make a chirping sound. The chirp would also cause Beret Guy's body to change form repeatedly and rapidly.

Transcript

[Beret Guy is standing to the right of Ponytail.]

Beret Guy: This new topical medication makes me extra sensitive to sun exposure and gravitational waves.

[Beret Guy's arms are out.]

Ponytail: Oh yeah, that's a common ...wait, what was that last part?

Beret Guy: Here comes one now!

[Ponytail stands facing Beret Guy, who is stretched out in height.]

[Ponytail stands facing Beret Guy, who is now shorter and wider than he was originally.]

[Ponytail stands facing Beret Guy, who is now stretched out in height again as he was in the third panel.]

Beret Guy: WHEEE!

Is this out of date? .

New here?

Last 7 days (Top 10)

Rank Score Pages Changes Username 1 28 18 41 YZ100 2 22 18 23 TheusafBOT 3 17 8 28 GSLikesCats307 4 11 8 11 FaviFake 5 11 9 10 Ally 6 11 6 12 BunsenH 7 8 3 9 Barry Margolin 8 7 2 9 DKMell 9 5 1 6 RadiantRainwing 10 3 3 3 Zowayix

Lots of people contribute to make this wiki a success. Many of the recent contributors, listed above, have just joined. You can do it too! Create your account here.

You can read a brief introduction about this wiki at explain xkcd. Feel free to sign up for an account and contribute to the wiki! We need explanations for comics, characters, themes and everything in between. If it is referenced in an xkcd web comic, it should be here.

• If you're new to wiki editing, see the explain xkcd:Editor FAQ for a specific guidance to this Wiki and the more general help on how to edit wiki pages. There's also a handy wikicode cheatsheet.

• Discussion about the wiki itself happens at the Community portal.

• You can browse the comics from List of all comics or by navigating the category tree at Category:Comics.

• There are incomplete explanations listed here. Feel free to help out by expanding them!

Rules

Don't be a jerk!

There are a lot of comics that don't have set-in-stone explanations; feel free to put multiple interpretations in the wiki page for each comic.

If you want to talk about a specific comic, use its discussion page.

Please only submit material directly related to (and helping everyone better understand) xkcd... and of course only submit material that can legally be posted (and freely edited). Off-topic or other inappropriate content is subject to removal or modification at admin discretion, and users who repeatedly post such content will be blocked.

If you need assistance from an admin, post a message to the Admin requests board.