Ohm
by Mike
Image text: More generally, with great power comes great dEnergy/dt.
Good old uncle Ohm. In this, not-quite-sure-it-happened-this-way, comic, Ohm's nephew (I'm presuming they both have the last name Ohm) is being given what would later become part of Ohm's law of electricity.
I = V/R
It relates the current I, to the voltage (electrical potential) V and resistance R.
Power is just current multiplied by voltage P = IV. Through substitution with Ohm's law we can see that power is also equal current I squared times resistance R.
The reason old uncle Ohm is stating it this way is probably because he's making a pun on how Peter Parker's (Spiderman's) uncle would relate his own dying words to his nephew many decades later. "With great power comes great responsibility"
Creepy
by Jeff
Image text: And I even got out my adorable new netbook!
This comic is a dream sequence for the male character for the first four frames. It appears to be a social commentary about why more single men and women don't randomly talk to each other. One side is waiting for the other to show the midlest interest and the other side is waiting for the other side to show interest as well. So, no one talks to anyone else and someone writes sadly into their blog.
Free
by Jeff
Image text: Asbestos is bad; definitely get the one on the right. Wait -- this one over here has no swine flu! Now I can't decide.
Explain XKCD is now 100% fat free!
This comic is a joke on how every food is attached with a label that says what it doesn't have (even and especially if there was no chance the food contained that type of item anyway).
One such offender is the label "99% fat free" on sugar products. Diet Blog has this to say:
99% fat free has to be one of the most idiotic labels known to mankind - particularly when applied to a carbohydrate food. Just this morning I was reading a "healthy food guide" I picked up from the supermarket. It turned out to be an advertising feature. One product featured was jasmine rice - claiming that it was "99% fat free".
The fat-free labels prey on a basic fear of fat. In the consumers mind, it must be a better choice if it has no fat in it. Manufacturers have been applying the fat free label to candies - many of which are nothing but straight sugar.
Tornado Hunter
by Jeff
Image text: The Fujita Scale was replaced by the Enhanced Fujita Scale in 2007, but I think 'EF-5' sounds stupid, so I vote we just use the new measurements for assigning numbers but still call them 'F-whatever'.
This is a riff on the show Discovery Channel show, Storm Chasers, in which they try to get as close to a tornado as possible with their highly tuned instruments.
This comic is a cross between Storm Chasers and a typical animal hunt in which the animal is shot and mounted as a prize.
The Fujita Scale is a hurricane rating system in which the size and strength of the tornado is rated based on damage on the ground from the tornado and wind speed.
Lincoln-Douglas
by Jeff
Image text: Stephen Douglas actually died soon after the debates and election, but if you demand historical accuracy in your webcomics you should be reading Hark! A Vagrant.
The image text is correct, Lincoln's Gettsyburg Address was in 1863 and Stephen Douglas died in 1861 of Typhoid.
And of course, the link to Hark! A Vagrant.
The Search
by Jeff
Image text: I am so excited about the Kepler mission. This is the second most important thing our species has ever done, right behind inventing the concept of delivery pizza.
The Kepler mission is a NASA-led research mission in which a telescope was launched into orbit around the sun. The focus of the telescope is to find other "Earth-like" planets that could sustain life.
The comic is saying that our search for life is as futile as the ants searching a dozen floor tiles in someone's kitchen. If those ants were in my kitchen, they wouldn't have to go far before finding my sentient life and feeling the wrath of my spray can of RAID.
Additionally, the Kepler Nasa site looks like it is from 1996.
Scribblenauts
by Jeff
Image text: Let me look away and type 'guy who's just jealous that I beat all his MarioKart times' and turn back, and ... yup, there you are again!
Scribblenauts is a side-scrolling game for the Nintendo DS in which you can summon objects to help you in the game, such as a ladder, or plants. "A fundamental element of Scribblenauts is the ability of the player to summon myriad objects into the game. This is achieved by writing the name of an object on the touchscreen (or via keypad)"
This comic takes that one step further and pokes fun at the prospect of summoning a friend in Scribblenauts by the phrase "Pretentious Asshole" or "guy who's just jealous that I beat all his MarioKart times"
The first two frames are making mention of the fact that there was some fear that the large hadron collider in CERN in Europe would create a black hole through their experiments. This was widely debunked, but apparently in Scribblenauts in xkcd, it does make a black hole.
Brontosaurus
by Jeff
Image text: Well, sex is like a velociraptor: despite your movie-fueled lifelong neurotic obsession, unlikely to be found in your house.
And here we continue xkcd's author's obsession with the cyncism about love.
Brontosaurus is an obsolete phrase for the Apatosaurus. Brontosaurus is the "popular" (but incorrect) name for the dinosaur, but Apatosaurus is the correct name.
Locke and Demosthenes
by Mike
Image Text: Dear Peter Wiggin: This letter is to inform you that you have received enough upvotes on your reddit comments to become president of the world. Please be at the UN tomorrow at 8:00 sharp.
This comic references the Orson Scott Card novel Ender's Game. [SPOILER] In it, Ender's higher-than-average intelligence siblings, Valentine Wiggin and Peter Wiggin decide to make a move for power on earth by posting contrasting opinions of the Formic War on their version of the internet. They used the pseudonyms Locke and Demosthenes respectively and eventually coerced the trust of the entire planet by playing their posts against each other. This lead to Peter gaining control of the free world.
[EXTRA SPOILER] Peter is a borderline sociopath and kills that squirrel.
Date
by Mike
Image Text: Well, the kid's definitely getting the biology geek phenotype.
Punnett squares are simple diagrams used to determine the odds of a particular offspring genotype (genetic make up) given the genotypes of the parents. The phenotype is the physical manifestation of the genes in the organism and doesn't always correlated directly to strict genotypes. Some genetic characteristics (like color blindness and eye color) can be easily traced using Punnett squares because they are the result of one clearly dominant gene and one clearly recessive. Other traits like height are a blend of multiple genes.
An interesting thing to note:
The male's parents were both colorblind but that is a recessive gene on the X chromosome. For his mother to be colorblind she must have had two copies of the gene. This man now carries the gene on his X chromosome so he will only pass it on to his daughter. She will be a carrier but will have normal color vision so long as this woman is not colorblind.