2579: Tractor Beam

Explain xkcd: It's 'cause you're dumb.
(Redirected from 2579)
Jump to: navigation, search
Tractor Beam
Did you base the saucer shape on pop culture depictions of aliens, or was that stuff based on your ships? Does the rotational symmetry help with ... hey, where are you going?
Title text: Did you base the saucer shape on pop culture depictions of aliens, or was that stuff based on your ships? Does the rotational symmetry help with ... hey, where are you going?


Cueball is being pulled into a spaceship by a beam of light, called a tractor beam in the title. This is a common trope in science fiction, and usually pretty scary for the person involved. However, while Cueball is being pulled up, he asks a series of questions about the beam, about the force on the ship, and about the ship itself. The punch line is the caption - the aliens, frustrated by Cueball's questioning, release him and move on, to presumably find a different human to abduct and study. Many people have reported being abducted by aliens in real life, though none of these have been confirmed[citation needed].

The first three questions deal with the properties of the beam – how it can be controlled to pull only him (and his clothes), not anything else. He also wonders whether the beam would still continue to lift his shoes if he took them off midway. Perhaps his apparel is only rising with him because it normally stays attached to him, perhaps it is similarly levitated with equal force or impulse. Theoretically, it could only lift his clothing, with enough force to hoist him along with it, though if this was done with insufficient finesse, it could cause damage to the clothing or the person. (One might be tempted to call this a Space Wedgie.) It is highly unlikely that this type of tractor beam could be used on Cueball without him realizing it, which would likely lead to him asking how the tractor beam lifted the clothes and not him.

Next, Cueball asks if his weight is pulling the ship downward. This would be the case, for example, if he were hoisted upwards by a rope instead of the beam, as equal but opposite forces act against each other, but not if the beam alters the nature of his surroundings such as with Cavorite or another means of gravitational shielding or alteration.

Then he asks what will happen if a bat flies through the beam. Things that could happen include the beam breaking (and him falling downward) due to the projected effect being interrupted, the bat being pulled up ahead of him as it enters the effective volume of the levitating beam or else nothing at all as it is outside the actual volumetric segment of the beam that is more than ambient light-effects. It may presumably have a relationship with the same focal effect as that which avoids the ground upon which he previously stood being drawn upwards. Also, the shadow of the bat on the ground might make the light beam look like an inverted Bat-Signal.

As the ship leaves, Cueball continues asking questions, as shown in the title text. Those questions address the shape of the ship. He asks whether the aliens based the saucer shape on depictions of extraterrestrials in earth popular culture, or if classic flying saucers were inspired by them. His next question was cut off, but what we heard is "does the rotational symmetry help with".

Whether Cueball actually arrived onboard the ship is uncertain. If he started badgering the aliens with questions during the lift and then (as stated) was immediately set down again then he did not. Either way, they got fed up and decided to return him to the ground instead of sharing their knowledge, or just because they preferred someone less talkative. They may prefer or expect more scared, overawed, or surprised abductees but, by whatever alien criteria they judge their catches, it seems he isn't what they want.

This was the third comic in less than three weeks featuring aliens using this type of flying saucer type spaceship. The other two comics were in a row just 6 and 7 comics before this one, 2572: Alien Observers and 2573: Alien Mission.


[A flying saucer type spacecraft hangs in the air above a flat area with scattered rocks and two hills in the background. A beam of 'light' emerges, a conical region textured with wavy lines radiating along its length, from a small square opening beneath the bottom of the craft going down to the ground a bit right of the saucer where its conceivably circular cross-section is rendered elliptic by both its angle of projection and our own viewing perspective. Cueball hangs suspended within the middle of the beam, above the ground but still some way from the saucer. His arms are held out to either side and his legs are bent up behind him. He is looking up at the saucer while talking.]
Cueball: Does this beam only lift me? How do you avoid pulling up dirt and leaves and stuff? If I kick off my shoes, will they fall?
Cueball: Is my weight pulling your ship downward? What will happen if a bat flies through the beam?
Cueball: Hey, why does your ship have those blinky lights? Are they...
[Caption below the panel:]
Moments later, the aliens set me back down and left.

comment.png add a comment! ⋅ comment.png add a topic (use sparingly)! ⋅ Icons-mini-action refresh blue.gif refresh comments!


This feels a lot like a SMBC outtake. (In a good way.) -- 20:42, 9 February 2022 (UTC)

This reads like a bash.org comment. (In a good way.) 21:24, 9 February 2022 (UTC)

So, if I were rising in a tractor-beam, I think there'd be clues as to the scope of the effects. Are my clothes hanging off me, floating round me or am I being upwardly cradled by them? Do I feel like I'm standing on something, hanging upside-down by my feet (from a topsy-turvey horizontal) or freefalling? What's my inner-ear telling me? Is the air around me rushing up, feels still (even though I'm moving vertically through it) or is it like I'm being raised up through it? Does the air feel like treacle, can I push against it, angle my arms to spin in the 'wind' like with indoor freefalling? Does any lateral wind still pass by as it did before the beam (small adjustments for being away from ground-effects, allowed for) or swirl oddly laterally or vertically? Is anything in the air (bat or smoke or rain or whatever dust I kicked up as I scrabbled for footing upon the first surprise of being tractored up) going up or down or neither, or revealing eddies? A bat, or anything else that flies, is going to have excess lift until any confusion (again with the inner-ear?) stops it from using its wings to counteract any non-existent 'weight' element, if applicable. If I hold one hand atop another (easier to experiment with, and switch over, than feet being below my torso, especially if I can't control attitude) do I feel a 'force shadow' where levity does not pass and/or gravity from below is no longer nullified/negated? Am I held as vertically (or similarly, perhaps can adopt a 'seated' poise) or am I unable to hold my attitude/able to change it? ...And loads more obvious things to potentially experience, depending upon how I deal with the first few tests and how quickly I can form less open-ended and more practical/emperical theories about what all I have started to learn means... 21:47, 9 February 2022 (UTC)

Hypothetically, Cueball might be being moved by forces similar to the one causing this - levitation would be an amazing thing to have --Wielder of the Staple Gun (talk) 01:28, 10 February 2022 (UTC)

Very interesting that Randall has been creating a string of comics on UFOs recently. Wonder if he knows something we don't? Jokes aside, it's interesting to see how his brain works, exclusively from a creative-output perspective. The string of UFO comics must be related to something that he experienced in his life recently. Similar to his cursed connectors run a few months ago: one can only wonder what weird, jerry-rigged solution he needed to some frustrating problem. 01:47, 10 February 2022 (UTC)

There has been a lot about UFOs spotted by the US Airforce, I think? I still don't believe it's aliens... It's never Aliens ;-) I guess once he get's one idea for a specific comic, then this may easily spawn other ideas. So I'm not sure there are any particular reason he got the first idea, but that may explain the others that followed. --Kynde (talk) 08:00, 10 February 2022 (UTC)

Let's imagine that a bat between the UFO and Cueball creates a shielding effect from the tractor beam. Part of Cueball would feel the traction but others not. He could be torn apart! Poor Cueball.

If not the part of his body that is not attracted simply goes along with the actively pulled parts, like when you lift a baby in its armpits.
While False (talk) 12:27, 10 February 2022 (UTC)

I feel like it is Randall, not Cueball, as it is "me" in the caption. 12:54, 10 February 2022 (UTC)Bumpf

Most comics could feel like Cueball is Randall. But when you see a person speaking in the comic, then it is that person that says set me down, in the caption. So I would still just say it is Cueball not Randall. Also I'm sure he has not been pulled up by traction beam... And even if this is how Randall would react in case of an abduction (I doubt it) he typically let Cueball have these far out reactions. --Kynde (talk) 17:12, 13 February 2022 (UTC)

What gets me is how Cueball will enter the hatch. If it's far enough 'into the drawing' to make it a person-sized hatch then the projective cone would shine an eliptical slice along the ground forelengthened far morenthan our viewpoint foreshortens it, so its major axis would be (on the image) vertical, not horizontal. For that ground-footprint, it's a smaller, closer craft. Still large, but the hatch is smaller than Cueball. Clearly, then, the tractor-beam is only used to raise the chosen subject off the ground, because (unlike the anti-gravity/levitation beam) the transporter-technology they actually use to ultimately bring a chosen subject into the ship itself cannot distinguish between a person and the ground they might be standing on. Risking either injurious impediments to the one being transported or tearing up some ground with them. (Leaving either foot-filled shoes or a 'divot' in the ground, to shock and/or excite those who discover the evidence of the abduction, and causing a mess for the aliens inside the vessel... either way.) This is clearly the only logical conclusion we can make. ;) 13:51, 10 February 2022 (UTC)

Maybe the hatch would just open up when he get's close...--Kynde (talk) 17:12, 13 February 2022 (UTC)

For me the first two questions are obviously linked to the tractor from the headline. Cueball is thinking about using the tractor beam of the UFO to plow a field. Thus he wants to know why the dirt is not being pulled up with him. I'm surprised this is not mentioned, so I might be totally wrong here. -- 11:50, 11 February 2022 (UTC)

Don't believe "tractor beam" has anything to do with a farming tractor. From Wikipedia, it says that "tractor beam" is short for "attractor beam". 17:27, 11 February 2022 (UTC)
However, xkcd is known for word play and for purposefully misunderstanding words with more than one meaning in the wrong context. -- 19:55, 11 February 2022 (UTC)
For sure but I'm quite sure the current explanation that Cueball wonders how the beam knows only to pull at him and not at anything else that is inside the beam, as his bat question reveals. If anything in the beam would float towards the spaceship then anything loose on the ground should follow Cueball. --Kynde (talk) 17:12, 13 February 2022 (UTC)

If he had been brought onboard the alien ship, I'm sure they would have still returned him sometime around the 25th time he asked, "Aren't we there yet?" – RAGBRAIvet (talk) 14:31, 14 February 2022 (UTC)