explain xkcd - User contributions [en]

3107: Weather Balloons

2025-06-25T19:55:29Z

2603:8080:BD00:5703:DA8:CD88:5D30:6397: Changed the incomplete explanation notice.

{{comic
| number = 3107
| date = June 25, 2025
| title = Weather Balloons
| image = weather_balloons_2x.png
| imagesize = 547x351px
| noexpand = true
| titletext = Once you add the balloons into the model, it makes forecasting easier overall--the forecast is always 'cold and dark, with minimal solar-driven convection.'
}}

==Explanation==
{{incomplete|This page was created by a METEOROLOGIST BOT WITH A BUNCH OF SPARE TIME. Don't remove this notice too soon.}}

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

{{comic discussion}}<noinclude>
[[Category: Line graphs]]
[[Category: Comics featuring Cueball]]
[[Category: Weather]]

3107: Weather Balloons

2025-06-25T19:47:16Z

2603:8080:BD00:5703:DA8:CD88:5D30:6397:

{{comic
| number = 3107
| date = June 25, 2025
| title = Weather Balloons
| image = weather_balloons_2x.png
| imagesize = 547x351px
| noexpand = true
| titletext = Once you add the balloons into the model, it makes forecasting easier overall--the forecast is always 'cold and dark, with minimal solar-driven convection.'
}}

==Explanation==
{{incomplete|This page was created by a WEATHER FORECASTING BOT WITH A BUNCH OF SPARE TIME. Don't remove this notice too soon.}}

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

{{comic discussion}}<noinclude>
[[Category: Line graphs]]
[[Category: Comics featuring Cueball]]
[[Category: Weather]]

3107: Weather Balloons

2025-06-25T19:37:31Z

2603:8080:BD00:5703:DA8:CD88:5D30:6397:

{{comic
| number = 3107
| date = June 25, 2025
| title = Weather Balloons
| image = weather_balloons_2x.png
| imagesize = 547x351px
| noexpand = true
| titletext = Once you add the balloons into the model, it makes forecasting easier overall--the forecast is always 'cold and dark, with minimal solar-driven convection.'
}}

==Explanation==
{{incomplete|This page was created recently. Don't remove this notice too soon.}}

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

{{comic discussion}}<noinclude>
[[Category: Line graphs]]
[[Category: Comics featuring Cueball]]
[[Category: Weather]]

3107: Weather Balloons

2025-06-25T19:35:42Z

2603:8080:BD00:5703:DA8:CD88:5D30:6397:

{{comic
| number = 3107
| date = June 25, 2025
| title = Weather Balloons
| image = weather_balloons_2x.png
| imagesize = 547x351px
| noexpand = true
| titletext = Once you add the balloons into the model, it makes forecasting easier overall--the forecast is always 'cold and dark, with minimal solar-driven convection.'
}}

==Explanation==
{{incomplete|This page was created recently. Don't remove this notice too soon.}}

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

{{comic discussion}}<noinclude>
[[Category: Line graphs]]
[[Category: Comics featuring Cueball]]

3107: Weather Balloons

2025-06-25T19:33:00Z

2603:8080:BD00:5703:DA8:CD88:5D30:6397:

{{comic
| number = 3107
| date = June 25, 2025
| title = Weather Balloons
| image = weather_balloons_2x.png
| imagesize = 547x351px
| noexpand = true
| titletext = Once you add the balloons into the model, it makes forecasting easier overall--the forecast is always 'cold and dark, with minimal solar-driven convection.'
}}

==Explanation==
{{incomplete|This page was created recently. Don't remove this notice too soon.}}

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

{{comic discussion}}<noinclude>
[[Category: Line graphs]]

3094: Mass Spec

2025-06-25T00:10:18Z

2603:8080:BD00:5703:DA8:CD88:5D30:6397: Removed the incomplete transcript notice, transcript seems good.

{{comic
| number = 3094
| date = May 26, 2025
| title = Mass Spec
| image = mass_spec_2x.png
| imagesize = 407x253px
| noexpand = true
| titletext = Patients at least found it to be an improvement over Millikan's incredibly messy and unpleasant oil drop suspension procedure.
}}

==Explanation==
The domestic bathroom scale (initially a form of {{w|spring scale}}) was only introduced to US customers in the early 1920s. Although means to ascertain the weight of the human body existed before the 1920s, they were not in common use and were not thought necessary in routine physical and medical examinations. The joke in this comic arises from the claim that, before the invention of the "modern" bathroom scale, human body weights needed to be obtained, not by the earlier, less convenient, forms of scale technology which were actually used, but by absurd, Rube Goldberg-esque, implementations of {{w|Mass_spectrometry|mass spectrometry}}.

Mass spectrometry, a late 19th-century invention (thus, available only a few decades earlier than the bathroom scale), was developed to obtain the masses of atomic particles by ascertaining their mass-to-charge ratios. The basic steps, as represented in the comic, are ionization of the mass (rubbing the scalp with the balloon), separating the resulting particles on the basis of their mass-to-charge ratio by firing them through a magnetic field (jumping past the magnet), and observing the resulting amount of path deflection on a detector (the target). Since the ionization procedure for ''bona fide'' mass-spectrometry assays involves turning the mass to be analyzed into a gas, the method would quickly be recognized as unsuited for obtaining human body weights, especially over the course of a dieting program, and become unpopular{{cn}}. There are other ionization techniques to transfer larger compounds intact into the gas phase, but a human body would be way too heavy to be analyzable by this technique.

The title text compares the mass-spectrometry-based method for obtaining human body weights with the method based on the {{w|Oil_drop_experiment|Milliken-Fletcher procedure}}, also available only a few years prior to bathroom scales, in which the mass to be analyzed takes the form of atomized oil droplets that are ionized by X-rays. Neither is suited for weight measurements over time scales of any length, but the cleanup procedures for a human body converted into ionized gas are certainly less onerous than those for a similar mass converted into an oil spray. The original procedure was intended to determine the mass of an electron, based on the known mass/density of the oil droplets. The title text seems to imply the converse, determining the mass/density of a person based on the (now) known mass of an electron.

==Transcript==

:[Ponytail, wearing a lab coat, is giving a balloon to Cueball. Behind Cueball, there is a ramp on the ground, a magnet hanging from the ceiling, and a target on a poster on the wall.]
:Ponytail: Rub this balloon against your head, then go jump past that magnet toward the target on the wall.

:[Caption below the panel:]
:Before the bathroom scale was invented, the only way to weigh people was mass spectrometry.

==Trivia==
In the comic, Randall uses the correct term "mass spectro'''metry'''". The term "mass spectro'''scopy'''" was used in the beginnings of the technique but is not used anymore. Today, a spectroscopy method entails the interaction of matter with electromagnetic radiation (e.g. IR light — as in IR spectroscopy or radio waves — as in NMR spectroscopy, nuclear magnetic resonance spectroscopy). In the case of mass spectrometry, this is not the case, as ions are manipulated or interacting with static electric and magnetic fields and thereby the mass-to-charge ratio is determined. Both "spectrometry" and "spectroscopy" allude to a "spectrum" of possible results that can be used to quantify and qualify any inputs being measured, and a distribution of molecular weights ''can'' be usefully represented in a rainbow-like visual, but doesn't bear any direct relation with the electromagnetic spectrum, hence the technical name difference. People "in the trade" often abbreviate it as "mass spec", which could stand for either term.

{{comic discussion}}<noinclude>
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Cueball]]
[[Category:Physics]]