1119: Undoing

Explain xkcd: It's 'cause you're dumb.
Revision as of 11:28, 10 October 2012 by (Talk)

Jump to: navigation, search
I've been sneaking out at night and installing lamps on the underside of every photovoltaic panel I can find. Sure, there are upwards of 80% losses, but I prefer to think of them as nearly 20% gains.
Title text: I've been sneaking out at night and installing lamps on the underside of every photovoltaic panel I can find. Sure, there are upwards of 80% losses, but I prefer to think of them as nearly 20% gains.


The comic is a play on regenerative energies and the way they transform the natural resources (wind, sun, water) into electricity.

The alt text is a reference to the very bad efficiency of solar panels (roughly 20-25%) and light bulbs (20-30%). Thus instead of only 80% loss of energy, which is either not converted to electricity or converted into heat) it's actually far more.

Thus the undoing done by the character is quite less effective than the common "Undo" function known from computers.


Comment.png add a comment!


Perhaps his motivation is to restore natural wind patterns to the environment. I remember reading about the ecological impact of wind power includes lessened wind currents. Some organisms rely on the wind to propagate the species, such as winds that blow seeds or how some spiders "parachute" on wind currents. Or it could be that he just likes to mess with people. --Joehammer79 (talk) 13:46, 10 October 2012 (UTC)

I always though that if you put a forest of windmills on top of hill the damage of ecosystem done by the building is enough. Adding the fact about wind used for propagating ... damn, windmills are almost as unecological as solar plants on fields ...
Seriously, how can anyone who things ecologically be AGAINST nuclear power? -- 08:19, 12 October 2012 (UTC)

At first I thought this should be more of a Blackhat trick, but since he seems to think he is creating good in the world by restoring, it makes sense that it is Cueball-- 14:35, 10 October 2012 (UTC)

Am I the only one who is also entertaining the possibility that the fan setup in the picture is not acting with, but rather counteracting the wind, which is turning the windmill that supplies it power? I understand that the alt-text makes it seem like Munroe's thinking about 'making up' for our interference with insolation (and presumably wind, water etc.) patterns. But, if we're going to bring in logic here, EVERYTHING falls apart :D I had a little fun trying to model what kind of a dynamic equilibrium the hitherto described windmill-fan arrangement would settle into. 17:13, 10 October 2012 (UTC)

I believe you are... The fan's blowing to the right... The wind came from the left... 21:35, 18 October 2012 (UTC)Robert

Indeed, the first thing that comes to mind is the "fan blowing into the sails" arrangement you sometimes see in cartoons, but I don't think that's what's going on here.CityZen (talk) 17:58, 10 October 2012 (UTC)

It's even more fun to do to condoms. --SuspendedPhan (talk) 18:50, 10 October 2012 (UTC)

What the hell is "rotational" energy?!
Although "rotational" energy exists (it is a verbal shorthand for kinetic energy that exists due to a rotating mass), what we actually have here is rotational power, another verbal shorthand for mechanical power transmitted by a rotating object working against a load. Also, Cueball has not disconnected the turbine from the generator but the generator from its electrical load (battery charger or electrical grid tie-in, perhaps).-- 13:20, 13 October 2012 (UTC)
As I understand it, he has disconnected the windmill that was supplying power to the grid and that windmill is now powering a fan which is creating suction which is pulling more wind through the windmill. 16:04, 17 October 2012 (UTC)
Personal tools


It seems you are using noscript, which is stopping our project wonderful ads from working. Explain xkcd uses ads to pay for bandwidth, and we manually approve all our advertisers, and our ads are restricted to unobtrusive images and slow animated GIFs. If you found this site helpful, please consider whitelisting us.

Want to advertise with us, or donate to us with Paypal or Bitcoin?