# Delta between I and J? **URL:** \ **Category:** Factual Questions\ **Created:** [April 11, 2024, 12:11am UTC](https://boards.straightdope.com/t/delta-between-i-and-j/1000122 "2024-04-11T00:11:11Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [April 11, 2024, 12:11am UTC](https://boards.straightdope.com/t/delta-between-i-and-j/1000122/1 "2024-04-11T00:11:11Z")
I was looking at a site where an author had posted some stories they had written. One of the stories started with the letter Δ (it was a science fiction story). If I was filing that story alphabetically, I’d probably put it at the end of the alphabet. Or maybe I’d put it in with the D’s. But this author had filed it between I and J (and it was an alphabetical list). Is there some convention that I am unaware of that puts Δ between I and J? ---
**Author:** ![What\_Exit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/what_exit/32/10652_2.png) [@What\_Exit](https://boards.straightdope.com/u/What_Exit)\ **Post date:** [April 11, 2024, 12:18am UTC](https://boards.straightdope.com/t/delta-between-i-and-j/1000122/2 "2024-04-11T00:18:08Z")
It’s the 4th letter of the Greek alphabet, so I don’t see how. I and J both derived from Iota, the 9th letter of the Greek alphabet. It would seem to be an odd affectation by the author. ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [April 11, 2024, 12:31am UTC](https://boards.straightdope.com/t/delta-between-i-and-j/1000122/3 "2024-04-11T00:31:14Z")
The only way such a system would make sense to me is if it’s not actually a delta, but represents some other symbol where this would make sense. However, there are other explanations for its location. For example, what is the second letter. I could see a system that just ignores characters not in the Latin alphabet. I could also see alphabetizing by another word in the title or by subject. ---
**Author:** ![Kimble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kimble/32/19185_2.png) [@Kimble](https://boards.straightdope.com/u/Kimble)\ **Post date:** [April 11, 2024, 2:20am UTC](https://boards.straightdope.com/t/delta-between-i-and-j/1000122/4 "2024-04-11T02:20:16Z")
It could be like titling a book _ρ_ and pronouncing/alphabetizing it as “[density](https://en.wikipedia.org/wiki/Density).” Perhaps Δ is supposed to be read as “interval” or something similar? I wouldn’t use or read it as such, but that could plausibly work in some physics/math contexts. Also, since it’s sci-fi, it could be something made up but vaguely related to real physics/math. (It could also be lower-case δ, but in uppercase because it’s part of the title.) ---
**Author:** ![Schnitte](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/schnitte/32/9033_2.png) [@Schnitte](https://boards.straightdope.com/u/Schnitte)\ **Post date:** [April 11, 2024, 7:31am UTC](https://boards.straightdope.com/t/delta-between-i-and-j/1000122/5 "2024-04-11T07:31:14Z")
What was the second letter, or entire first word, of the title of the story? Perhaps the author used the delta to indicate the difference between two parameters that started with an I and filed it accordingly, arguing that the delta is silent and the first non-silent letter of the story was therefore the I. ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [April 11, 2024, 3:16pm UTC](https://boards.straightdope.com/t/delta-between-i-and-j/1000122/6 "2024-04-11T15:16:56Z")
> [@Schnitte](#): > > What was the second letter, or entire first word, of the title of the story? The complete title of the story was ΔV. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [April 11, 2024, 4:07pm UTC](https://boards.straightdope.com/t/delta-between-i-and-j/1000122/7 "2024-04-11T16:07:34Z")
**After multiplying by the mass** that would give you _impulse,_ not without though. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [April 11, 2024, 5:22pm UTC](https://boards.straightdope.com/t/delta-between-i-and-j/1000122/8 "2024-04-11T17:22:58Z")
> [@Little\_Nemo](#): > > The complete title of the story was ΔV. So it really should have filed under the A’s for “acceleration”. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [April 11, 2024, 9:03pm UTC](https://boards.straightdope.com/t/delta-between-i-and-j/1000122/9 "2024-04-11T21:03:28Z")
FWIW, I would have alphabetized it as delta. There is a concept in mathematics called \*-autonomous category. I believe it is alphabetized as star. ---
**Author:** ![Elmer\_J.Fudd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/elmer_j.fudd/32/1211_2.png) [@Elmer\_J.Fudd](https://boards.straightdope.com/u/Elmer_J.Fudd)\ **Post date:** [April 12, 2024, 7:37pm UTC](https://boards.straightdope.com/t/delta-between-i-and-j/1000122/10 "2024-04-12T19:37:10Z")
> [@Little\_Nemo](#): > > The complete title of the story was ΔV. Is it a mixed alphabet word meant to mean “Delta-V”? ---
**Author:** ![Dr\_Paprika](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr_paprika/32/3042_2.png) [@Dr\_Paprika](https://boards.straightdope.com/u/Dr_Paprika)\ **Post date:** [April 13, 2024, 5:12pm UTC](https://boards.straightdope.com/t/delta-between-i-and-j/1000122/11 "2024-04-13T17:12:35Z")
The angle between i and j is usually 90 °. Guessing that is not what is meant; maybe it is just a meaningless affectation?