The “Pip! is Nonbinary” FAQ

Over the past year or so, I’ve come to an understanding of myself having a nonbinary gender identity.  This is a set of frequently asked questions (with answers) I’ve fielded about that transition.

§ What does “nonbinary gender identity” mean?

It means I don’t feel I fully belong to the group of people labeled “men” and I also don’t feel I fully belong to the group of people labeled “women”.  That puts me outside of the traditional gender binary, or “nonbinary” for short.

Nonbinary is a pretty broad label.  It encompasses a diversity of gender identities, including people whose gender identity fluctuates over time (genderfluid, bigender), people who don’t feel any gender identity applies to them (agender), people who feel like a blend of gender identities (androgynous, among others, and note that not everyone has a 50%/50% blend), and many others.  For me, it’s more of a default setting, defined by the absence of a strong male or female identity.

§ Does that mean you’re transgender?

Yes.  My gender identity as I currently understand it is different from the gender identity I wore as I was growing up.  (The latter is sometimes called AGAB, short for “assigned gender at birth”.)  That makes me transgender, or trans for short.  (Note that “trans” is an adjective, not a noun.  I am trans, and I am a trans person.  It is incorrect—both grammatically and in a dehumanizing way—to say that anyone is “a trans.”)

Recall from the previous question that “nonbinary” encompasses many different gender identities.  Some nonbinary people do not see themselves as trans, though any nonbinary person may if they so choose.  I am one of those who do.

§ Is your name changing?

Yes.  I’m going by Piper or Pip now, instead of Phil and Phillip.

My old names aren’t terribly antithetical to me.  I’ve used them for many years at this point.  They’ll always be part of my past identity.  But I feel a bit of distance now between the name “Phil” and how I see myself.  Just as I expected people to adjust when I started going by Phil instead of Phillip, I hope that people can now adjust to me going by Piper (or Pip, if you’d prefer).

§ How should I refer to you when talking about you with someone who might not know your current name?

Use my current name, but you can add some clarification on the first use.  For example:

“I was talking with Piper the other day (who you might know as ‘Phil’, but they go by Piper now).”

§ Are your pronouns changing?

Yes and no.  The short answer is that you can use whatever pronouns you feel best fit me, but if you’re not sure what to use, “they/them” is a good default.

The longer answer is that I don’t feel a strong enough affinity to any particular gender identity to actively claim one set of pronouns to the exclusion of others.  Using a singular “they” for a specific person still feels a bit unusual to me, even though I’ve been doing it for a while now, and even though the singular “they” predates not just Shakespeare but the singular “you”.  As a result, I currently prefer to let people choose what pronouns they feel comfortable using for me.  (But, again, if you’re not sure, give “they/them” a try.)

This can result in some unavoidable confusion when two or more people are talking about me and each uses a different set of pronouns.  I’m sorry about that, but this still seems to be the best approach for me at the moment.

§ What honorific should people use for you instead of “Mister”?

This doesn’t come up very often, but please use “Mx.” (pronounced “mix”), as in “Mx. Piper” or “Mx. Gold”.

§ What if I accidentally use the wrong name or pronouns for you?

If you’re trying to adapt to this change but you use my old name out of habit, don’t stress about it.  Just briefly correct yourself—“Sorry; I meant Piper.”—and move on.  I don’t expect anyone to instantly change they way they refer to me after years of using the old way.  The new things will come with practice, and practice includes sometimes making mistakes, learning from them, and continuing on.

Also, as noted above, you can use whatever pronouns you feel best fit me, so you can’t even use the wrong ones by my definition.

§ Is your email address changing?

Yes.  The old one will continue to work (indefinitely, or as long as that’s feasible), but I’m now using .

It might be some time before I have my email address (and displayed name and account name) updated everywhere I have an account online.

§ Are you going to look different than you used to?

Yes.  I’m wearing more overtly-feminine clothes than I used to, and I’ve adopted some other forms of presentation that are more socially associated with women than with men.

This is all a process of finding which things feel comfortable for me, which feel uncomfortable, and which don’t feel relevant one way or another.

§ Why are you doing this now (as opposed to earlier in your life)?

Although I was raised as a boy and have lived for many years as a man, I’ve felt drawn to more feminine aspects of gender identity and presentation for most of my life.  But my discomfort at being confined to a male identity (also known as gender dysphoria) was never strong enough to outweigh the social pressures against coming out as a trans woman.

The biggest thing that changed was a greater awareness, on both my part and society’s, of nonbinary gender identities.  Just having nonbinary as an option felt incredibly freeing to me.  It gave me a space to explore my gender identity and presentation without feeling I had to stay in a 100% male role or transition to a 100% female identity.

(I do still have to sort myself into binary categories on occasion, like when a public facility doesn’t have gender-neutral or single-occupancy bathrooms.  I usually take an ad hoc approach and try to pick the option that I think will confuse the fewest number of people.)

§ Why are you doing this now (as opposed to never)?

As I noted above, I’ve always felt drawn to more of a female identity than I felt I was allowed to express.  Having to live with that was a persistent, low-grade pressure at the back of my mind.  I was constantly trying to decide how much I could subtly step into feminine things without explicitly claiming anything other than a male identity.

Once I started exploring a nonbinary identity, I found that I was much more comfortable and happy with the way I lived and presented myself.  And once I started feeling happier with nonbinary expressions, the times when I was restricted to male-only presentation felt more and more uncomfortable.

In short, I’m happier now, even with all of the uncertainty and opposition in some parts of society to trans people.  Staying closeted (or going back to being closeted) would be tantamount to saying, “Well, I guess I’ll just live with being unhappy for the rest of my life.”  I’m not going to do that.

§ Other questions?

I’m happy to answer or discuss most honest, respectful questions.  Feel free to reach out to me.  Friends and family should have my contact information already.  For everyone else, my email address is linked at the bottom of this page.  Be aware that it does often take me a while to get around to responding to emails, even from people I know.

Garmin Lily 2 Watch Faces

I recently got a Garmin Lily 2 smartwatch.  When I was deciding what watch to get, I went looking to see what different watch faces the Lily 2 had.  I couldn’t find such a list online at the time.  Now that I have a Lily 2, I’m making that list for other people’s reference.

The Lily 2 is a fitness tracking smartwatch from Garmin.  It’s the smallest and lightest smartwatch they offer, and its features are a bit limited in comparison to other Garmin smartwatches.  One of those limitations is in the area of watch faces.  The Lily 2 does not support Garmin Connect IQ watch faces.  It has its own set of predefined faces that you can choose from.

Each watch face shows at least the time and has a spot for additional information.  That spot shows one piece of information at a time.  You can cycle through the available pieces of information by tapping on the watch face.  Some watch faces also have pieces of information (e.g. current heart rate) that they always show, in addition to the cyclable information slot.

The pieces of information available for the cyclable slot are:

  • Steps
  • Heart Rate
  • Body Battery
  • Calories
  • Weather
  • Battery (watch battery level)
  • Garmin Logo

You can restrict the actually-displayed pieces of information in the settings, if you don’t want to go through all of them all the time.  I only show weather and device battery; I use widgets to show the other information when I want to see it.

Although it’s not an option for the cyclable information, some watch faces show the current date.  Those that do so always use the same formatting for it, showing the abbreviated day of the week and the day of the month.

In the images below, the spot for cyclable information will be shown as the Garmin logo.  That serves to distinguish it from the always-shown information, since no watch face has an always-shown Garmin logo.

  • Digital clock, with seconds
  • Analog clock, with seconds
  • Digital clock
  • Date
  • Digital clock
  • Date
  • Calories
  • Steps
  • Digital clock
  • Date
  • Heart Rate
  • Digital clock
  • Body Battery
  • Date
  • Analog clock, with seconds
  • Digital clock
  • Date
  • Heart Rate

Note: See below for a description of the grey arc at the top. 

  • Digital clock
  • Date
  • Weather
  • Calories

The next to last face shown above has a grey arc at the top of the face.  When the cyclable display is showing a bit of information that can be viewed as a percentage (device battery, body battery, steps (as a percent of the daily goal), etc.), a section of that arc is illuminated in proportion to the percentage.

I have a Lily 2 Classic, but I believe the (non-Classic) Lily 2 has the same faces.  This information is accurate as of March 2024 and firmware 3.11.  Newer firmware might add, remove, and change the watch faces available.

Éowyn Challenge – Mordor!

Back in 2022, I started “Walking to Mordor and Back”.  Briefly, that involves seeing how long it takes me to walk as far as Frodo did in The Lord of the Rings.  For more information, see my previous post on the topic.

As of December 20, I’ve reached Mount Doom in Mordor!  That’s a total of 1,779 miles walked in just under two years since January 1, 2022.  The same journey took Frodo about six months, so he definitely made better time than I did.

LaTeX Sentence Spacing

As a followup to my general post about sentence spacing, here are some brief notes about managing sentence spacing in LaTeX, followed by a not-so-brief explanation of what LaTeX is doing.

By default, LaTeX adds slightly more space between sentences than it does between words.  The space between sentences is about 33 percent wider than the space between words.

You can disable this extra space entirely with the \frenchspacing directive.  From the point LaTeX encounters that directive until the end of the document (or until it reaches a \nofrenchspacing directive), it will use the same amount of space between sentences as between words.

LaTeX tries to figure out where sentences end and apply the extra space on its own.  It usually does a good job, but sometimes it guesses wrong.  Fortunately, it has options for you to adjust its word and sentence spacing yourself, so you can almost always get it to do what you really want.

§ LaTeX’s Basic Rules

The basic rules are these:

  1. A sentence-ending punctuation character (a period, exclamation point, or question mark) followed by a space is considered to signal the end of a sentence.
  2. There can be any number of right parentheses, quote marks, and right brackets between the punctuation and the space.
  3. However, if the character immediately before the punctuation is a capital letter, LaTeX will not end a sentence there.

So these would all be seen by LaTeX as sentence breaks and would get extra space added during text layout:

…thank you. You're…
…the best.  No one…
…else is.         Except…
``Stop!'' The word…
…really right?)  Anyway…

These, however, would not be treated as the ends of sentences:

A Ph.D. in what…
She was SHOUTING.  I didn't like it…

§ Non-sentence Punctation

If you have some punctuation that makes LaTeX think there’s a sentence where there isn’t, you have two options available to you.

A lot of the time, the false sentences come from things like abbreviated titles, e.g. Mr. Rogers.  In those cases, you would probably prefer to tightly bind the two words together.  For that, you can use a tilde to add a nonbreaking space, which LaTeX also calls a tie:


LaTeX will not break a line at a nonbreaking space, nor will it stretch nonbreaking spaces when justifying lines.

In other cases, you might want LaTeX to treat the space after the punctuation as a normal space that can be wrapped and stretched as needed.  There are two ways to do that.

One option is to use the \@ macro between the punctuation and the space.  This interrupts LaTeX’s sentence-ending calculations and causes it to treat the subsequent space like a normal inter-word space.

It was David vs.\@ Goliath all over again. 
``What are you doing?\@'' she asked. 
``What are you doing?''\@ she asked. 
There are many options, e.g.\@ a polar bear. 

Alternately, you can use \ (a backslash followed by a space) to explicitly tell LaTeX to use a normal space at that location, regardless of what its calculations say:

It was David vs.\ Goliath all over again. 
``What are you doing?''\ she asked. 
There are many options, e.g.\ a polar bear. 

The second option is, as you can see, a little more concise.

§ Unrecognized Sentence Punctuation

Conversely, sometimes you have sentences that end with a capital letter right before the period (or other end-of-sentence punctuation).  In that case, you can put \@ just before the punctuation to make sure LaTeX adds the extra space you want between that sentence and the next one:

He had a PhD\@. That worried me. 

As in the previous examples, \@ interrupts LaTeX’s special spacing calculations.  When placed before sentence punctuation, it causes LaTeX to ignore the immediately-preceding character, which means its special “capital before punctuation” rule never comes into play.

§ Sentences Without Recognized Punctuation

On rare occasions, I’ve run into cases where I’d like to have sentence spacing after characters that LaTeX doesn’t normally recognize as sentence-ending.

For example:

I thought---  No, that's not right. 

The best approach I’ve found for this is:

I thought---\spacefactor3000{}  No, that's not right. 

The short explanation for that wordy construct is that it’s forcing LaTeX’s layout engine to apply end-of-sentence semantics at the macro location.  (It might or might not help to know that \@ is basically equivalent to \spacefactor1000{}.)

§ More Details than You Probably Want

The above should be sufficient if you just want to know how to get or suppress LaTeX’s end-of-sentence spacing as needed.  But if you want to know what’s going on under the hood, feel free to read on.

# Space Factors

Every character in TeX has a numeric “space factor” assigned.  That space factor primarily affects the rate at which space after the character is allowed to grow or shrink as TeX adjusts the width of a line to make it justified.  When TeX expands a space, it does it in proportion to the space factor divided by 1000.

Most characters have a space factor of 1000.  That means most inter-word spaces use a proportion of 1 for expansion or, in other words, TeX will expand or shrink all of the spaces by the same amount all the time.

Some characters have a slightly larger space factor.  Commas have a space factor of 1250, for instance, and semicolons have a space factor of 1500.  So let’s say there’s a comma in a line of text and TeX wants to make the line wider.  For every 1 point of space that TeX adds to the “normal” spaces in the line (the ones with a space factor of 1000), it will add 1.25 points to the space after the comma.  (When shrinking space, TeX uses the inverse of that proportion.  So if the normal spaces were decreased by 1 point, the space after the comma would only be decreased by 1/1.25 or 0.8 points.)

# Widening a Space Based on the Space Factor

In addition to these rules about growing and shrinking spaces, TeX has another rule, which is that if a character’s space factor is greater than or equal to 2000, it automatically adds an extra amount to the width of the following space.  That extra amount is defined by the font, but most fonts are pretty similar to the default Computer Modern.  Ten-point Computer Modern uses a width of 3.3333 points for normal spaces and adds an extra 1.1111 points when the “extra space” rule is triggered.

The three standard end-of-sentence punctuation marks—period, question mark, and exclamation point—all have space factors of 3000.  Colons have a space factor of 2000.  So all four of those characters will trigger the addition of extra width to any space that directly follows them.  Spaces after end-of-sentence punctuation will grow three times faster than normal spaces and shrink at one third their rate.  Spaces after colons will grow twice as fast and shrink at half the rate of normal spaces.

# Skipping Some Characters’ Space Factors

A few other punctuation characters have space factors of zero.  These are all characters that sometimes appear between sentence punctuation and the space after the sentence.  They include the right parenthesis, single quote mark, and right bracket.

When TeX encounters a character with a space factor of zero, it carries over the space factor from the previous character.  This allows the spacing algorithm to effectively ignore some characters.  As an example, consider the string “a.) ”.  The “a” has a space factor of 1000.  The “.” has a space factor of 3000.  The “)” has a space factor of zero, which means TeX will carry over the previous value of 3000.  When it finally reaches the space, TeX will use the 3000 value to add extra space and grow the space at three times the rate of a normal space.

# Capital Letters

The final rule TeX has is that if a character has a space factor less than 1000 (but greater than zero) and the next character has a space factor greater than 1000, that next character’s space factor is reduced to just 1000.

All capital letters hava a space factor of 999.  That means any of the special-spacing characters effectively lose their special space factor after a capital letter.  The spaces after “PhD.”, “NASA:”, and “FOMO;” will be normal spaces and will not have any extra width added to them.

# Setting the Space Factor Explicitly

You can set a space factor explicitly at any point with the \spacefactor command, followed by the new value.  As usual in TeX, you can have an explicit assignment (\spacefactor=1000) or allow TeX to figure it out implicitly (\spacefactor 1000 or \spacefactor1000).  Also as usual, the command will consume any space characters after it, so you need an empty statement after it if you want to preserve the space (\spacefactor1000{}).

# Putting it All Together

All of that should explain why the LaTeX macro \@ is equivalent to \spacefactor1000{}.  When placed between a capital letter and a period, it forces the pre-period space factor to 1000, which in turn allows the period to trigger the usual extra space and altered growth and shrinking behaviors.  When placed between a period and a space, it forces the space to see a space factor of 1000 and be treated as a normal space.

The “\ ” (backslash space) macro always inserts a space with a space factor of 1000, which is why it’s equivalent to (and can be seen as a shorthand for) “\@ ” (backslash at space).

§ Reference Material

The bulk of this information can be found in TeX by Topic, chapter 20.  See also the LaTeX2e reference on \spacefactor, an answer to “Is it possible to have non-french spacing without extra stretch?” on the TeX Stack Exchange, and a similar answer to “What is the proper use of \@ (i.e., backslash-at)?”.

Sentence Spacing

One lump or two?

There is an ongoing debate in some parts of the Internet about how much space should go after the end of a sentence.  Practically every publisher and quite a lot of other people will say there should be one space.  A minority of people—principally Gen X and older, I suspect—will say there should be two spaces.

I have opinions.

In short:  Two spaces are too much.  One space is okay, but it can feel a little crowded.  Adding just a little extra space—about 33 percent more—after a sentence gives a nice balance.  This blog does the latter.

§ A Brief History of Sentence Spacing

In the earliest days of the printing press, the standard among typesetters was to have about three times more space between sentences than between words.  But even their inter-word spaces were much larger than we use today.  In numeric terms, there was a space of one em between sentences, and one-third of an em between words.  An “em”, for our purposes, is simply a unit of measurement in printing that scales in proportion to the size of the type.  For example, text set at 72 points will have an em size of one inch, while 36 point text will have an em size of half an inch.  This proportionality makes the em a convenient reference for the sizes of things in typeset text.

Here’s how those earliest spacing conventions might look with some sample text:

As Gregor Samsa awoke one morning from uneasy dreams, he found himself transformed in his bed into a gigantic insect. When he lifted his head a little, he could see his dome-like brown belly. The bed quilt could hardly keep in position and was about to slide off completely. His numerous legs, which were pitifully thin compared to the rest of his bulk, waved helplessly before his eyes. It was no dream. His room, a regular human bedroom, only rather too small, lay quiet between the four familiar walls.

When typewriters, with their fixed character widths, became common, people tried to adapt printing rules that had been developed for proportional typefaces.  Typewriters’ fixed-width spaces were a little larger than the printers’ third-of-an-em proportional-type spaces.  Typing conventions eventually settled on a single fixed-width space between words and two fixed-width spaces between sentences.

If it were typed according to these rules, our sample text would look something like this:

As Gregor Samsa awoke one morning from uneasy dreams, he found himself transformed in his bed into a gigantic insect.  When he lifted his head a little, he could see his dome-like brown belly.  The bed quilt could hardly keep in position and was about to slide off completely.  His numerous legs, which were pitifully thin compared to the rest of his bulk, waved helplessly before his eyes.  It was no dream.  His room, a regular human bedroom, only rather too small, lay quiet between the four familiar walls. 

During the twentieth century, publishers gradually began to close up spacing in their printing, both between words and between sentences.  In the first part of the century, inter-word spacing remained roughly a third of an em, but inter-sentence spacing shrank to half an em.  That gave something along these lines:

As Gregor Samsa awoke one morning from uneasy dreams, he found himself transformed in his bed into a gigantic insect. When he lifted his head a little, he could see his dome-like brown belly. The bed quilt could hardly keep in position and was about to slide off completely. His numerous legs, which were pitifully thin compared to the rest of his bulk, waved helplessly before his eyes. It was no dream. His room, a regular human bedroom, only rather too small, lay quiet between the four familiar walls.

During the second half of the twentieth century, professional publishers continued to close up inter-word and inter-sentence spacing.  By the end of the century, most publications used just a quarter of an em between both words and sentences.  I have seen speculation that the convergence between inter-word and inter-sentence spacing grew out of increasing use of automated typesetting.  (“Two Spaces - an Old Typists' Habit?” gives a brief history of automated typesetting and makes a plausible case for how the extra inter-sentence space was lost.)

This sort of spacing is what you’re almost certainly used to seeing everywhere, but here’s what it looks like with our sample text:

As Gregor Samsa awoke one morning from uneasy dreams, he found himself transformed in his bed into a gigantic insect. When he lifted his head a little, he could see his dome-like brown belly. The bed quilt could hardly keep in position and was about to slide off completely. His numerous legs, which were pitifully thin compared to the rest of his bulk, waved helplessly before his eyes. It was no dream. His room, a regular human bedroom, only rather too small, lay quiet between the four familiar walls.

Now, well into the twenty-first century, pretty much every newspaper, magazine, and book publisher uses the same amount of space between sentences as between words, and that space is generally about a quarter of an em.  Every major style guide recommends typing a single space after a sentence.  The only significant exceptions, as far as I can tell, are scientific journals that use LaTeX for their typesetting (and which haven’t explicitly turned off LaTeX’s extra inter-sentence spacing).

§ Readability Studies

Practically every study done on the readability effects on end-of-sentence spacing has been inconclusive.  The one exception is “Are two spaces better than one?” by Johnson, Bui, and Schmitt.  That study purported to find that putting two spaces after sentences improved readability exclusively for people who themselves put two spaces after sentences when writing.  The findings are even weaker than that summary implies, however, for reasons that are covered well by Matthew Butterick.  In short, the test conditions were well outside normal reading conditions and there were unexplored statistical differences between the overall reading abilities of one- and two-space-using readers.

In other words, no one has really demonstrated a tangible benefit to any variation of end-of-sentence spacing.

§ Aesthetics

So that leaves just the question of aesthetics.  What looks good?

As noted previously, nearly every newspaper, magazine, and book you read uses the same amount of space at the end of a sentence as between words.  Nearly every website you read is the same, unless the website author has gone out of their way to do something different.  Everyone reads things with just one space between sentences all the time, so there’s the aesthetics of familiarity, if nothing else.

My personal view is a little more nuanced than just one space versus two.  Using a single space is servicable and two spaces are probably a bad idea, but I think I can do better than either.

Let’s look again at our example text with one space after each sentence:

As Gregor Samsa awoke one morning from uneasy dreams, he found himself transformed in his bed into a gigantic insect. When he lifted his head a little, he could see his dome-like brown belly. The bed quilt could hardly keep in position and was about to slide off completely. His numerous legs, which were pitifully thin compared to the rest of his bulk, waved helplessly before his eyes. It was no dream. His room, a regular human bedroom, only rather too small, lay quiet between the four familiar walls.

I find that readable, but it also feels a bit crowded.  The sentences seem to run together without any room to breathe.

Let’s put two spaces after each sentence and see how that looks:

As Gregor Samsa awoke one morning from uneasy dreams, he found himself transformed in his bed into a gigantic insect.  When he lifted his head a little, he could see his dome-like brown belly.  The bed quilt could hardly keep in position and was about to slide off completely.  His numerous legs, which were pitifully thin compared to the rest of his bulk, waved helplessly before his eyes.  It was no dream.  His room, a regular human bedroom, only rather too small, lay quiet between the four familiar walls.

To me, that feels like too much space.  As I read the paragraph, the extra space between sentences feels almost like an interruption each time.

I mentioned earlier that some publishers still use LaTeX’s inter-sentence spacing.  In particular, LaTeX allocates 33 percent more space at the end of a sentence than it does between words.  (For very specific numbers, see this Stack Exchange answer on the topic.)  If a standard inter-word space is now a quarter of an em, that should lead to inter-sentence spacing of a third of an em.  Here’s what that looks like:

As Gregor Samsa awoke one morning from uneasy dreams, he found himself transformed in his bed into a gigantic insect. When he lifted his head a little, he could see his dome-like brown belly. The bed quilt could hardly keep in position and was about to slide off completely. His numerous legs, which were pitifully thin compared to the rest of his bulk, waved helplessly before his eyes. It was no dream. His room, a regular human bedroom, only rather too small, lay quiet between the four familiar walls.

Personally, I like that balance of spacing.  There’s a very slight extra bit of space between sentences, but not enough that it really draws attention to itself.  This is often the sort of spacing I use when I’m writing longer-form things in HTML that don’t need to adhere to some surrounding style conventions.  For reference, I’m using Unicode character U+2004 THREE-PER-EM SPACE between sentences.  It can be represented in HTML using the XML entity  .

But I actually do something slightly different on this blog.  Because I’m picky about a variety of minutiae, I want this blog to look “right” (according to me) in all sorts of environments, including in text-mode web browsers (and, I guess, in other browsers that use monospaced fonts).  So this blog ends sentences with a combination of a regular space character and U+2009 THIN SPACE (or  ).  In a monospaced font, those will be shown as two full-width spaces.  In proportional fonts, the thin space is typically somewhere between a sixth and a fifth of an em.  In the font I use, it’s closer to a fifth.  Consequently, in most browsers those two spaces will add up to just a tiny bit more than my preferred total of a third of an em between sentences.

That combination of spaces looks like this (and also like every regular bit of text on this blog):

As Gregor Samsa awoke one morning from uneasy dreams, he found himself transformed in his bed into a gigantic insect.  When he lifted his head a little, he could see his dome-like brown belly.  The bed quilt could hardly keep in position and was about to slide off completely.  His numerous legs, which were pitifully thin compared to the rest of his bulk, waved helplessly before his eyes.  It was no dream.  His room, a regular human bedroom, only rather too small, lay quiet between the four familiar walls.

The Chicago Manual of Style, a fairly conservative style guide, has a blog article about their one-space recommendation, as well as their own history of sentence spacing in publishing.

The Associated Press Stylebook doesn’t have anything online that’s publicly accessible, but a Journalist’s Resource basic guide to the AP style summarizes the guidance as, “Use only one space after the end of a sentence. Period.”

The Modern Language Association, whose style guide is used in many academic settings, says to use one space after a period unless specifically directed otherwise by an instructor.

The American Psychological Association, one of the last holdouts for using two spaces after a sentence, updated their guidelines in 2019 to recommend a single space.

Microsoft Word started flagging two-space sentences as errors in 2020.

Matthew Butterick, a well-regarded typographer online, calls the use of two spaces a “typewriter habit”—a holdover from the days of typewriters that no longer serves any useful purpose.

It’s a little difficult to find a comprehensive online LaTeX reference about its sentence spacing.  It doesn’t help that many LaTeX people seem a bit bitter about the ubiquity of using a single space to separate sentences.  (For example.)  Probably some of the most thorough coverage is in (some of) the answers to the TeX Stack Exchange question “Double space between sentences”.

§ In Conclusion

Don’t type two spaces after sentences in a medium with a proportionally-spaced font.  The closest typographic convention to this practice hasn’t been in use professionally for over a century, and it doesn’t look great alongside modern fonts and typography.

If your only choices are between using two standard spaces and a single standard space after your sentences, use the single space.

In many environments, the choice between one and two spaces is a false dichotomy.  If you can, try adding just a little extra space between your sentences.  I find that sentences look good with about 33 percent more space between them than between the words they contain.  I probably wouldn’t add more than about 50 percent of my inter-word spacing to the ends of my sentences.