Of Particular Significance

Celebrating 2/22/22 (or was it 22/2/22)?

POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 02/23/2022

I hope you all had a good Twosday. Based on what I saw on social media, yesterday was celebrated widely in many parts of the world that use Pope Gregory’s calendar. I had two sandwiches to in honor of the date, and two scoops of ice cream.

In the United States, the joy continues today, it being now 2/23/22. Though not quite as wonderful as 2/22/22 on Tuesday, it’s still another nicely symmetric number worthy of note. In fact we get a full week of this, including 2/24/22 tomorrow, 2/25/22 on Friday, and so on, concluding on 2/29/22 … uhh, (oops) I mean, 2/28/22, because 2022 is not a Leap Year. For some reason.

In other countries, where it is 23/2/22, the celebration is over for now … because without symmetry, where’s the love? Ah, but they’re just more patient. They’ll get their chance in a month, when it’s 22/3/22, a date that will go unnoticed in the USA but not in Europe.

But what, exactly, are we getting so jazzed about? After all, what is the significance of it being the 22nd or 23rd date of the second month of a year labelled 2022? Every single bit of this is arbitrary. Somebody, long ago, decided January would be the first month, making February month number 2; but it wasn’t that long ago that March was the first month, which is why September, October, November and December (7, 8, 9, and 10) have their names. It’s arbitrary that January has 31 days instead of 30; had it been given thirty, the day we call the “22nd” would have been the “23rd” of February, and our celebration would have been one day earlier. And 2022 is arbitrary two too. Other perfectly good calendars referred to yesterday by a completely different day, month and year.

This, my friends, is exactly what General Relativity (and the rest of modern physics) tells you not to do. This is about putting all of your energies and your focus on your coordinate system — on how you represent reality, instead of on reality itself. The coordinate system is arbitrary; what matters is what actually happens, not how you describe what happens using some particular way of measuring time, or space, or anything else. To get excited about the numbers that happen to appear on your measuring stick is to put surface ahead of substance, math ahead of physics, magic ahead of science. It’s as bad as getting excited about how a word is spelled, or even what word is used to represent an object; a rose by any other name.

But we humans are not designed to think this way, it seems. We cheer when we’ve driven a thousand miles, a milestone (hah) which combines the definition of mile (arbitrary) with the fascination with the number 1,000 (which only looks like an interesting number if you count with ten fingers, rather than 12 knuckles, as the Babylonians did, or eight tentacles, as certain intelligent sea creatures might do.) We get terribly excited about numbers such as 88, or 666, which similarly depend on our having chosen to count on our ten fingers. A war was ended on 11/11 at 11:00 (and one was started on 22/2/22 — coincidence?)

Celebrating birthdays is a little better. No matter what calendar you choose, or whether it even lasts a year (as, for example, in Bali), the Sun appears to move across the sky, relative to the distant stars, in a yearly cycle. When it comes back to where it was, a year has passed. If we define your age to be the number of solar cycles you’ve experienced, then that means something, no matter what calendar you prefer. Your birthday means something too as long as we define it not by the arbitrary calendar but by the position of the Sun on the day of your birth.

Similarly, the solstices that mark the days with the shortest daylight and shortest darkness, and the equinoxes that have days and nights equal in duration, are independent of how you count hours or minutes or seconds, or even days. It doesn’t matter if your day has 24 equal hours, or if you divide your daylight into 12 and your darkness into 12, as used to be the case. It doesn’t matter what time zones you may have arbitrarily chosen. If you want to mark days, you can use the time that the Sun is highest in the sky to define “noon”, and count noons. A year is just over 365 noons, no matter what your calendar. The time from solstice to solstice is about half that. But the date we call “December 25th” does not sit on a similarly fundamental foundation; it shifts when there’s a leap year, and sometimes it’s three days after the solstice and sometimes four. Many other holidays, driven by Moon cycles rather than a Sun cycle, are even less grounded in the cosmos.

Being too focused on coordinates can cause a lot of trouble. The flat maps that try to describe our spherical Earth make all sorts of things seem to be true that aren’t. They all make the shortest path between two points impossible to guess. Some wildly exaggerate Greenland’s size and minimize the entire African continent. Most of them make it difficult to imagine what travel over the north or south pole is like, because there’s a sort of “coordinate singularity” there — a single point is spread out over a whole line at the top of the map, and similarly at the bottom, which makes places that are in fact very close together seem very far apart.

A coordinate singularity of a more subtle type prevented scientists (Einstein among them) from realizing for decades that black holes, which were once called “frozen stars,” have an interior, and that you could potentially fall in. The coordinates originally in use made it seem as though time would stop for someone reaching the edge of the star. Bad coordinates can obscure reality.

Physics, and science more generally, pushes us to focus on what really happens — on events whose existence does not depend on how we describe them. It’s a lesson that we humans don’t easily learn. While it’s fine to find a little harmless and silly joy at non-events such as 22/2/22 or 2/22/22, that’s as far as it should go: anything that depends on your particular and arbitrary choice of coordinate system cannot have any fundamental meaning. It’s a lesson from Einstein himself, advising us on what not two do.

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5 Responses

  1. “A war was ended on 11/11/11 (and one was started on 22/2/22 — coincidence?)” Probably, seeing as WW1 ended on 11/11/18. 🙂

    1. Ohhhh, Man! Those are always the sorts of completely silly things that slip by my five proofreads. Yes indeed, 1918, on 11/11 at 11 in the morning. Just got a little carried away there…

  2. Black holes have an interior? My current understanding is that if a particle is to enter that interior, it needs to exceed the velocity of light, and that is impossible irrespective of coordinate / reference system applied? And similarly, a particle trying to leave the black hole needs to slow down to below c? Where does it leave its excess momentum? Taking that view further, a black hole’s mass would not be localized inside the hole, but in the accretion disk surrounding it? ? ?
    And to top it up, if I remember correctly then Gerald Feinberg showed sometime in the 1970’s that if faster-than-light matter exists, it will loose mass and momentum the faster it moves, accelerating itself towards infinite velocity and zero mass-energy, which implies to my non-mathematical, but thermodynamics trained mind that the interior of a black hole becomes increasingly more massless the deeper we move inside, and thus that the black hole’s mass is being concentrated in its accretion disk. What I do not recall is anybody with the appropriate mathematical competence having applied this to black holes – mathematical concepts that are inherently unobservable using astronomical instruments, whether these are photon receiving telescopes or gravity wave detecting interferometers. Observable quantities are only what consequences these mathematical concepts imply for the movement of other objects . . .
    Will you please elaborate?
    Another puzzle you might want to consider is the Big Bang. By extrapolating the Hubble parameter towards velocity of light, the age of the universe becomes sometime near 13 billion years. But if we shrink the currently observable universe by moving backward in time while preserving its mass, the universe will all vanish inside a black hole only a billion years ago – Where does the light come from that we observe from galaxies with a redshift indicating their light was emitted several billion years ago?
    The easy answer is, of course, that the mass of the observable universe is (approximately) proportional to the third power of its observable radius, meaning that at the time of the Big Bang, the observable universe had no mass at all . . .
    But with no mass for the very early universe, the cosmic microwave background loses its interpretation, and so does Cosmic Inflation . . .

  3. Here I am thinking all this time that it was Julius and Augustus Caesar elbowing their way into the calendar which messed up its numerically symmetrical bliss. I’ll have to double check on that.
    Congratulations on making it through this post without once using the word palindrome.
    One thing about the coordinate system of longitude and latitude is we also use it to find the stars in the sky at a particular time. Another thing is each degree is roughly 111km. In Google Maps, for example, you can simply click on a location and a pop-up window will give latitude and longitude data to a millionth of a degree. Further refinement to a millionth of a millionth degree would place one within the quantum realm. What a totally useless place to be without a coordinate system. Maybe one will pop into existence.
    Happy whatever spacetime it is. May your posts always bring you and your readers joy.

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