xkcd.WTF!?

Explanation ➲

In this comic, Randall is making fun of how oxygen deprivation can lead to reduced mental acuity. Dizziness, lightheadedness, impaired judgment, and euphoria are symptoms of oxygen deprivation, or hypoxia. Those researchers would benefit from having a written list or plan developed while they were still functioning at peak mental acuity. Note that high altitude does not lead to severe effects as described in the comic.

Here, two astronomers are heading up a mountain, towards the observatory they work at. Initially, they discuss what they are planning on doing once they reach the summit, mentioning Iodine cells, used for wavelength calibrations of high-resolution RV spectra between 501 and 610 nm. As they continue, the mental clarity of the researchers devolves as they approach the high altitude telescope, leading to increasingly juvenile and almost intoxicated behavior. One researcher mentioned her head feels funny, while the other makes a remark about taping down the observatories to prevent them from rolling away, an absurd remark considering observatories are firmly rooted and even if they weren't, it would take an excessive amount of tape to stop them from rolling away.

Once inside the observatory, they have completely forgotten about their original plans. Instead of doing a general calibration, they are playing with the telescopes, looking at each other's faces through them and deciding to make out with each other. This is why Randall mentions that astronomers working at high altitude observatories must write down their plans ahead of time at sea level, as the low oxygen leads to reduced mental acuity.

It should be noted that the phrase "low oxygen" would usually refer to the lower partial pressure of oxygen at altitude. The proportion of oxygen at high elevations is still approximately a fifth of the atmosphere, the same as at sea level, and there is not a significant stratification of gases that means oxygen (moreso than the other major constituents of air) can only be found at lower altitudes, nor that they encounter a distinctively different "high (altitude) oxygen" (though something different of that kind exists even higher up, not relevent to this scenario). The altitude sickness is caused by lowered atmospheric pressure which leads to smaller amount of oxygen actually delivered ("pushed") into bloodstream.

The title text refers to a laser guide star, a device for focusing telescopes by making artificial reference points in the sky. The reference points are created by shooting a powerful laser into the sky. The concern of the astronomer in the comic is that an imagined "star cat" may be attracted to the laser in the same way that cats playfully chase laser beams projected on surfaces. Cats' reactions to laser pointers were previously explored in 729: Laser Pointer.