explain xkcd - User contributions [en]

2549: Edge Cake

2021-12-03T16:44:02Z

Thirdjal: /* Explanation */

{{comic
| number = 2549
| date = December 1, 2021
| title = Edge Cake
| image = edge_cake.png
| titletext = Every time IERS adds or removes a leap second, they send me a birthday cake out of superstition.
}}

==Explanation==
{{incomplete|Created by FRINGE FRUITCAKE – Please change this comment when editing this page. Do NOT delete this tag too soon.}}

[[Megan]]—possibly an {{w|IERS}} (International Earth Rotation and Reference Systems) agent—wishes Emily, represented as [[Hairbun]], Happy Birthday. This prompts a confused [[Cueball]] to ask if her birthday was sometime last month. Emily explains that she was born over the North Pole in a plane, meaning that she was born in every timezone at once. Technically though this is false, as there are some timezones (such as {{w|Nepal Standard Time|UTC+5:45}}) that are not represented at the north pole. Except for the one hour before it's midnight at the International Date Line, the date in eastern time zones is one day ahead of western time zones. She also says that it was February 29th (presumably it was also February 28 or March 1 in some time zones). February 29th only happens at most once every four years in the Gregorian calendar, adding to the confusion - people born on February 29th often celebrate their non-leap-year birthdays on arbitrary days (or {{w|The_Pirates_of_Penzance#Synopsis|not at all}}). Normally {{w|Birth aboard aircraft and ships|one could simply use the time zone of the city the airplane took off from}}, but the airline company was changing ownership from one country to another at the time, so this option has apparently been ruled out. (Although, given the complexity of transferring a company's incorporation between different nations' business-law codes (eg. what is a LLC in the USA corresponds to a BV in the Netherlands or a GmbH in Germany) and company registries, it may have been the case that at the exact time Emily was born, the airline was either still incorporated in country #1 or had been incorporated in country #2).

The punchline is that rather than try to identify the correct birthday for Emily, the {{w|BIPM}} has decided to let her have birthdays whenever she wants.

Both the comic title and Cueball's final line are puns on "{{w|edge case}}", an engineering term referring to situations or conditions that are unusual in a way likely to cause problems unless specifically accounted for. Edge pieces are generally only important with sheet goods (brownies sheet cakes, etc), which are typically cut into pieces creating a difference between pieces originating on the edge and pieces originating from the center. Since the sides of a cake are often frosted, an edge piece has two faces covered in frosting and a corner piece has three, while a center piece only has one. Depending upon your relative preferences between the surface (often icing over marzipan) and core body of the cake (which can be fruitcake, or some variety of spongecake, etc, but not actually obvious which until the cake is cut), it being an edge-faced slice can be considered a bonus. Cueball certainly seems to appreciate this.

The title text states that the {{w|IERS}} sends Emily a cake every time they add or remove a leap second, out of superstition (perhaps Megan is delivering that cake). The International Earth Rotation and Reference Systems Service is in charge of global time standards. It occasionally adds one leap-second to {{w|Coordinated Universal Time}} to adjust for changes in the rotation speed of the Earth.

==Trivia==
Hairbun was last named "Emily" in [[788: The Carriage]]. More specifically, that version of Hairbun represented Emily Dickenson, a real, historical person who had no such issues regarding her birthday.

==Transcript==
:[Megan is walking towards Cueball and Emily (who resembles Hairbun), holding a cake.]
:Megan: Happy birthday, Emily!
:Cueball: Wait, wasn't that last month? When's your birthday, anyways?
:Emily: It's complicated.

:[A diagram of a flight path over the North Pole, with meridian lines radiating out from the center. Emily's dialogue appears above the diagram, but she herself does not appear in this panel.]
:Emily: My mom went into labor on an arctic international flight that diverted directly over the North Pole.
:Emily: I was born in every time zone at once.

:[With Megan standing behind her, Emily holds out a plate of cake to Cueball.]
:Emily: It was also February 29th, and the airline was just changing ownership between countries.
:Emily: The International Bureau of Weights and Measures finally issued a declaration that it's my birthday whenever I want.
:Emily: Cake?
:Cueball: Nice, it's all edge pieces.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Hairbun]]
[[Category:Time]]
[[Category:Engineering]]
[[Category:Science]]

2549: Edge Cake

2021-12-03T16:43:11Z

Thirdjal: /* Explanation */

{{comic
| number = 2549
| date = December 1, 2021
| title = Edge Cake
| image = edge_cake.png
| titletext = Every time IERS adds or removes a leap second, they send me a birthday cake out of superstition.
}}

==Explanation==
{{incomplete|Created by FRINGE FRUITCAKE – Please change this comment when editing this page. Do NOT delete this tag too soon.}}

[[Megan]]—possibly an {w|IERS} (International Earth Rotation and Reference Systems) agent—wishes Emily, represented as [[Hairbun]], Happy Birthday. This prompts a confused [[Cueball]] to ask if her birthday was sometime last month. Emily explains that she was born over the North Pole in a plane, meaning that she was born in every timezone at once. Technically though this is false, as there are some timezones (such as {{w|Nepal Standard Time|UTC+5:45}}) that are not represented at the north pole. Except for the one hour before it's midnight at the International Date Line, the date in eastern time zones is one day ahead of western time zones. She also says that it was February 29th (presumably it was also February 28 or March 1 in some time zones). February 29th only happens at most once every four years in the Gregorian calendar, adding to the confusion - people born on February 29th often celebrate their non-leap-year birthdays on arbitrary days (or {{w|The_Pirates_of_Penzance#Synopsis|not at all}}). Normally {{w|Birth aboard aircraft and ships|one could simply use the time zone of the city the airplane took off from}}, but the airline company was changing ownership from one country to another at the time, so this option has apparently been ruled out. (Although, given the complexity of transferring a company's incorporation between different nations' business-law codes (eg. what is a LLC in the USA corresponds to a BV in the Netherlands or a GmbH in Germany) and company registries, it may have been the case that at the exact time Emily was born, the airline was either still incorporated in country #1 or had been incorporated in country #2).

The punchline is that rather than try to identify the correct birthday for Emily, the {{w|BIPM}} has decided to let her have birthdays whenever she wants.

Both the comic title and Cueball's final line are puns on "{{w|edge case}}", an engineering term referring to situations or conditions that are unusual in a way likely to cause problems unless specifically accounted for. Edge pieces are generally only important with sheet goods (brownies sheet cakes, etc), which are typically cut into pieces creating a difference between pieces originating on the edge and pieces originating from the center. Since the sides of a cake are often frosted, an edge piece has two faces covered in frosting and a corner piece has three, while a center piece only has one. Depending upon your relative preferences between the surface (often icing over marzipan) and core body of the cake (which can be fruitcake, or some variety of spongecake, etc, but not actually obvious which until the cake is cut), it being an edge-faced slice can be considered a bonus. Cueball certainly seems to appreciate this.

The title text states that the {{w|IERS}} sends Emily a cake every time they add or remove a leap second, out of superstition (perhaps Megan is delivering that cake). The International Earth Rotation and Reference Systems Service is in charge of global time standards. It occasionally adds one leap-second to {{w|Coordinated Universal Time}} to adjust for changes in the rotation speed of the Earth.

==Trivia==
Hairbun was last named "Emily" in [[788: The Carriage]]. More specifically, that version of Hairbun represented Emily Dickenson, a real, historical person who had no such issues regarding her birthday.

==Transcript==
:[Megan is walking towards Cueball and Emily (who resembles Hairbun), holding a cake.]
:Megan: Happy birthday, Emily!
:Cueball: Wait, wasn't that last month? When's your birthday, anyways?
:Emily: It's complicated.

:[A diagram of a flight path over the North Pole, with meridian lines radiating out from the center. Emily's dialogue appears above the diagram, but she herself does not appear in this panel.]
:Emily: My mom went into labor on an arctic international flight that diverted directly over the North Pole.
:Emily: I was born in every time zone at once.

:[With Megan standing behind her, Emily holds out a plate of cake to Cueball.]
:Emily: It was also February 29th, and the airline was just changing ownership between countries.
:Emily: The International Bureau of Weights and Measures finally issued a declaration that it's my birthday whenever I want.
:Emily: Cake?
:Cueball: Nice, it's all edge pieces.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Hairbun]]
[[Category:Time]]
[[Category:Engineering]]
[[Category:Science]]