This panel is a play on the Electromagnetic spectrum, showing a large piece of the spectrum and examples of phenomena that absorb or emit light along the spectra. The first two scales at the bottom show the wavelength ? (in meters) and the frequency f (in Hertz) of the wave. In 1887 the Michelson–Morley experiment proved for the first time that the aether theory was wrong. The wavelength starts at high values on the left and decreases in a logarithmic scale to the right.
The rays controlling Steve Ballmer are nonsense, but may reference real Balmer series, a set of transitions in the hydrogen atom that produce photons in the optical and ultraviolet light range.
AM Amplitude modulation, VHF Very high frequency, and UHF Ultra high frequency are frequency ranges approved for commercial broadcasting companies. Cell phone cancer rays is playing with the belief of many people that cell phones may cause cancer (see also 925: Cell Phones). Aliens belong to a range slightly higher than the frequencies used by human communications. SETI is the "Search for ExtraTerrestrial Intelligence" project trying to find messages from aliens.
FHF is probably "Fucking high frequency"; it is not an abbreviation for any broadcasting frequency ranges and lies above the (real) V(ery)HF and U(ltra)HF. This is a pun on the microwave oven, which emits light at its namesake frequencies to cook food. The human visible spectrum is shown by all colors, including octarine, the colour of magic on the fictional Discworld (in the books by Terry Pratchett). No entry because it's censored; this is a humorous exaggeration of how much authority the government can supposedly exercise under said bill. Potatoes absorb and reflect radiation waves the same way humans do, because their chemistry and water content is very similar to the human body. Mail-order x-ray glasses refers to a novelty item based on an optical effect, not actual x-rays. And finally the Title Text: Randall likes to speculate what the world would look like if humans could see radio waves, gamma waves, etc. X-rays (from about 1nm to about 10pm); a line above shows the frequency of mail-order x-ray glasses. Going forward, I'll assume Wikipedia's "Be bold" guideline applies to this wiki (although not part of the wikimedia project), too.
The year 1897 might refer to Joseph Larmor's publication about the later so-called Lorentz transformation.
While it might be possible to connect certain VR goggles or similar glasses-like periphery to some full body scanners, they are usually operated with screens that do not resemble spectacles.
It's been a week and there have not been any replies, so if there still aren't any for another week (i.e. Is the second sentence of the title text ("Also sometimes I try to picture your sister naked.") a reference to how X-Ray Specs were sometimes advertized? Regarding the reference to microwave ovens in the explanation, I would like to point out that comic 843:Misconceptions references the list of common misconceptions, which in the Food and Cooking section clearly states that microwaves don't work at the frequency of water but instead uses dialectric heating to cook food. The electromagnetic range is the extent of all conceivable frequencies of electromagnetic radiation.

When you tune your radio, watch TV, send a text message, or pop popcorn in a microwave oven, you are using electromagnetic energy. Electromagnetic energy travels in waves and spans a broad spectrum from very long radio waves to very short gamma rays. Our Sun is a source of energy across the full spectrum, and its electromagnetic radiation bombards our atmosphere constantly.
NASA spacecraft, such as RHESSI, provide scientists with a unique vantage point, helping them "see" at higher-energy wavelengths that are blocked by the Earth's protective atmosphere. Electromagnetic radiation is reflected or absorbed mainly by several gases in the Earth's atmosphere, among the most important being water vapor, carbon dioxide, and ozone. While our atmosphere is essential to protecting life on Earth and keeping the planet habitable, it is not very helpful when it comes to studying sources of high-energy radiation in space. Mission:Science is provided by NASA's Science Mission Directorate to engage students in NASA Science and showcase educational resources created by NASA and its partners.
Such spectra are commonly used in physics or astronomy education contexts when discussing the nature of light.
The year (1897) cited underneath the comic title may be an incorrectly-dated reference to this experiment. As a result of the inverse relationship between frequency and wavelength, the frequency scale starts at low values and increases logarithmically.
For frequencies above 100 tera-Hertz, it just says "other entertaining Greek prefixes like peta- and exa- and zappa-". These can be either longitudinal or transverse waves, depending on the manner in which the Slinky is driven. Kosher is a Jewish law for food and it states, amongst other, that Jews are never allowed to eat meat from the unclean pigs - so no ham! Most genuine astronomical research in this area concentrates in the microwave and radio regimes. It also takes a stab at people who claim that microwaved food is dangerous, by pointing out that toasters also heat food using electromagnetic radiation, of frequencies just higher than microwaves. The reference to Superman covers his heat vision power, which has been used many times within the canon.
While dark is the opposite of light in many grammatical context, in the physical sense it only reflects the absence of visible photons.
These are the two most common elements in the Sun, and their presence in the Sun's outer envelope and Earth's atmosphere does block some small frequencies from the Sun. Such a thought experiment would be pretty abstract due to the total lack of a frame of reference (since everything outside the visible light spectrum is by definition invisible and thus beyond human comprehension) but for many people that's also what makes it enticing. They were formerly carried by the aether, which was decommissioned in 1897 due to budget cuts. Thus, I'll continue to make changes I consider uncontroversial without first discussing them, if I'm sufficiently confident in them, including major ones.
Obviously that comic is later than this one, but it should be considered for the explanation above.
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. However, the Earth's atmosphere protects us from exposure to a range of higher energy waves that can be harmful to life.

Some radiation, such as visible light, largely passes (is transmitted) through the atmosphere. Instruments have to be positioned above Earth's energy-absorbing atmosphere to "see" higher energy and even some lower energy light sources such as quasars.
This comic extends it to absurd lengths by including examples that may be variously hyper-specific, humorous, or non-EM phenomena.
Nevertheless, after that time many physicists like Hendrik Lorentz or Joseph Larmor were still working on some aether theories.
The nonsense Q parameter does not change monotonically with either frequency or wavelength. The last prefix should be zetta- (denoting a factor of 1021), but is intentionally mislabeled, referencing musician Frank Zappa.
Notably Randall has drawn the Slinky as tangled up; if you've ever played with a Slinky you know how frustrating it is to untangle it.
Since aliens work at different frequencies on this diagram, that might explain why there has of yet been no positive results from SETI. Randall immediately turns this profound train of thought around with a crude joke that he wants to know what the viewer's sister would look like in the nude. Above that are bars showing the absorption spectra for hydrogen, helium, Depends(R) (yellow only) and Tampax(R) (red only). In judging how controversial a potential change might be, I'll take the respective article's edit history and talk page into account.
However, I will not re-do my second change without explicitly putting it up for discussion here on the talk page, first, as I expect it to be a bit more controversial.
A radio detects a different portion of the spectrum, and an x-ray machine uses yet another portion. Gamma rays, x-rays, and some ultraviolet waves are "ionizing," meaning these waves have such a high energy that they can knock electrons out of atoms. These regions of the spectrum with wavelengths that can pass through the atmosphere are referred to as "atmospheric windows." Some microwaves can even pass through clouds, which make them the best wavelength for transmitting satellite communication signals. Photons do not have volume in the traditional sense of the word, and are electrically neutral (thus carrying no charge).
Albert Einsteins theory of Special Relativity in 1905 helped explain the theoretical basis for lack of aether and was a definitive step in discarding previous work.
I try to write good edit summaries, so these should usually give you my reason or motivation for making the edit it question.
NASA's scientific instruments use the full range of the electromagnetic spectrum to study the Earth, the solar system, and the universe beyond. Exposure to these high-energy waves can alter atoms and molecules and cause damage to cells in organic matter. These changes to cells can sometimes be helpful, as when radiation is used to kill cancer cells, and other times not, as when we get sunburned.

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Rubric: Canada Emergency Preparedness


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