“When the World As You’ve Known It Doesn’t Exist” could describe the way many people feel about the world today. It’s actually the title of the contemporary work on this weekend’s Boston Symphony Orchestra bill by Tennessee native and Pulitzer Prize winner Ellen Reid, but the remaining two pieces also take us where the orchestral world as we know it doesn’t often go: to Tchaikovsky’s “other” piano concerto, the neglected No. 2, and Sibelius’s 7^th Symphony, which explores the outer reaches of the symphonic universe. Thursday’s performances, with BSO assistant conductor Anna Rakitina on the podium and French pianist and 2019 International Tchaikovsky Competition winner Alexandre Kantorow as the concerto soloist, were otherworldly in quality as well: Kantorow sounded phenomenal, Rakitina hardly less so. And Reid’s piece occupied a world of its own.

The Tchaikovsky concerto, which runs close to 45 minutes, had the first half to itself, in, believe it or not, something of a  Symphony Hall debut. The most recent BSO performances had been in Tanglewood—in 1986, with Viktorina Postnikova as soloist, and in 1969, with Gary Graffman. The Pops programmed it in Symphony Hall in 1944 and 1945, and before that the BSO played it in 1912 (under Karl Muck) in Symphony Hall and in 1898 in the Boston Music Hall. But those Boston performances would have used the “edited” 1897 version of the concerto. After Tchaikovsky’s death, his former pupil Aleksandr Ziloti made major cuts and transpositions in an attempt to create a more conventional work; he reduced the slow movement to half its original length. That edition ruled the roost for the first half of the 20^th century; it’s the version you hear in the recordings by Emil Gilels and Shura Cherkassky and the score for George Balanchine’s 1941 Ballet Imperial (later revised and renamed Tchaikovsky Piano Concerto No. 2). Nowadays, in concert and on recordings, the piece is almost always performed as Tchaikovsky wrote it.

Boston audiences heard the concerto a bunch of times in the spring of 2019, when Ukrainian pianist Alex Poliykov soloed in Boston Ballet’s staging of Tchaikovsky Piano Concerto No. 2, but that was the Ziloti version. As far as I can make out, Thursday marked not just the debut of Tchaikovsky’s own version in Symphony Hall, but its debut in Boston, period. We surely have Kantorow to thank for that. At the 2019 International Tchaikovsky Competition, he was the only piano finalist to play the Second Concerto rather than the First, and he took first prize.

Granted, the Second, which Tchaikovsky completed in 1880, is an odd duck. Piano and orchestra spend most of the 20-minute opening Allegro brillante trying to avoid each other. The first theme in G major is followed by a second subject group in the surprise key of E-flat major, after which the movement spends an inordinate amount of time in C major. Tchaikovsky’s idea of sonata form is, to say the least, idiosyncratic; cadenzas pop up where you don’t expect them, and in the middle of the development the time signature changes from 4/4 to 12/16 and a sudden Andante gives way just as suddenly to Prestissimo. The Andante non troppo slow movement begins with a cantilena for solo violin that’s eventually joined by solo cello; the piano doesn’t enter for a good four minutes, and the whole has the aspect of a piano trio with bits of orchestra. That’s what flummoxed Ziloti, who trimmed the movement from some 16 minutes down to eight.

The late Gennady Rozhdestvensky conducted my two favorite recordings: with Igor Zhukov (1969) and then with his wife, Postnikova (1984). The latter reading is majestic to a fault, with an Allegro brillante that begins at an Andante-like metronome mark of 92, but Postnikova and Rozhdestvensky make it work. Kantorow and Rakitina adopted a tempo closer to what Tchaikovsky intended. Rakitina was regal to start, as if she had in mind Balanchine’s vision of the concerto as a naval academy graduation ball in tsarist St. Petersburg, the young officers and their ladies. The C-major fanfare at bar 201, some six minutes in, rose to a glorious moment of perfection, beauty that won’t last once the officers go out into the world.

But this was Kantorow’s show, and what a show. Crisp and aristocratic to start, he enjoyed tender support from Elizabeth Klein’s flute, and when he did accompany the orchestra, the warmth and clarity of his passagework complemented rather than competed. In the lyrical second subject group, he was rhapsodic, and that remained his pattern throughout the Allegro brillante, now hyperromantic in moonlit reverie, now stormy and passionate in his cascading cadenzas. In a movement that makes dizzying demands on the soloist, he tossed off torrents of notes without hammering or blurring; it all gleamed crystalline.

For the Andante non troppo, BSO assistant principal cellist Oliver Aldort moved from his usual position on Rakitina’s right to join associate concertmaster Alexander Velinzon on her left. Both soloists were heartrendingly bittersweet in a melody that, it’s been suggested, Tchaikovsky gave to the violin and cello because it suits strings better than it does the piano. Yet when he entered, Kantorow, combining license with noble restraint, made the theme sound as if it had been written specifically for his instrument, and even more specifically for him. When the three soloists played together, he blended in as easily as if this were a string trio and his piano a viola.

The trumpets at the close of the Andante sound an ominous note, as if time were intruding on the enchanted ball. That doesn’t preclude the concerto from concluding with a rollicking finale. Tchaikovsky marked this movement Allegro con fuoco, and it comes as a jolting surprise when it erupts out of the final pppp of the Andante. It was unfortunate, then, that Thursday’s performance required a pause so that Aldort could return to the cello section. In Tchaikovsky’s time, when first and second violins were seated antiphonally, the principal cello would have been close to the concertmaster, but that’s not the case with the BSO’s current arrangement, the norm these days, where the violins and cellos face each other on opposite sides of the conductor. I’m not sure what the solution could have been. In the event, Kantorow shot out of the gate, and if he dazzled in the first two movements, he was downright pyrotechnic in the third. Here, despite Tchaikovsky’s aversion to hearing piano and orchestra play together, he lets them, and Kantorow and Rakitina showed they can do it well.

We got not one encore but two: Giovanni Sgambati’s arrangement of the “Dance of the Blessed Spirits” from Gluck’s Orfeo ed Euridice and Guido Agosti’s arrangement of the finale from Stravinsky’s Firebird. Kantorow was delicately chaste in the first, and then so kaleidoscopic in the second as to make Stravinsky’s superb orchestration seem redundant.                               

The New York Philharmonic commissioned When the World As You’ve Known It Doesn’t Exist as part of its Project 19, wherein 19 women are composing new works to celebrate the centennial of the 1922 19^th Amendment, which gave women the right to vote. Reid, whose opera p r i s m won the 2019 Pulitzer, has said that When the World As You’ve Known It Doesn’t Exist “is not directly about the 19th Amendment, but it is about unabashedly presenting my artistic voice. This, at times, feels like my most political action.” The 11-minute piece, which Jaap van Zweden and the New York Philharmonic premiered in 2020, calls for a fairly standard large orchestra; what’s unusual is the division of the strings into as many as 12 parts, and the presence of three sopranos singing wordless texts.

Reid came on stage to give a brief introduction; I caught mention of “gut-wrenching lows” and “incredible beauty” and “the incredible musicians of the BSO.” The hyperbole, it turned out, was unnecessary. When the World As You’ve Known It Doesn’t Exist begins with the sounds of otherworldly nature. When the strings attempt a theme, they run into Reid’s trio of sopranos (Eliza Bagg, Martha Cluver, and Estelí Gomez in these performances), who seem to be mediating between the three Graces and the three Weird Sisters from Macbeth. In what Reid calls “a musical landscape of exhausted and disembodied questioning,” the syncopated irruptions of brass and bass drum and eerie percussion effects embody her “waves of blazing anger and strength.” The returning sopranos begin to sound more like the wordless female chorus at the end of Holst’s “Neptune.” High-pitched strings, still bedeviled by the rest of the orchestra, barely prevail before dying away into outer space.

Reid has packed more music into 11 minutes than one can comfortably digest at one sitting. I hope the BSO gives When the World As You’ve Known It Doesn’t Exist another outing.

Written in 1924, Sibelius’s final published symphony (he never completed the Eighth) unfolds as one continuous 22-minute movement hovering between 3/2 and 6/4, C major and C minor. Like his Sixth Symphony, it keeps lapsing into the Dorian mode, and like the Sixth, it grew out of a proposed tone poem addressed to Kuutar, the Finnish goddess of the moon; the opening Adagio develops from music called “Tähtölä” (“Where the Stars Dwell”).

It begins with a flash of soft timpani and a rising C-major scale in the strings that, in typical Sibelius fashion, starts on G and ends on A-flat. After two minutes of woodwind meditation, the violas and cellos begin a hymn designed to invoke the god. At the five-minute mark, solo trombone proclaims that god (perhaps the Finnish forest deity, Tapio, whom Sibelius would immortalize the following year in the tone poem Tapiola). What for a few blessed seconds is musical heaven doesn’t last; the forest animals panic, much as they do in the “What the Animals of the Forest Tell Me” movement of the Mahler Third. The symphony grows agitated, prompting the return of the trombone solo in C minor; then the music, through a pastoral episode, works its way back to C major and the trombone’s third and final call. After such knowledge, however, there’s no innocence. What’s left, over the final four or so minutes, are fragments, the strings keening, the brass intoning the trombone theme as threnody. The C-major benediction affirms the logic, the harmony, of the universe — which in 1946 Sibelius said “is precisely what I call God.”

Rakitina began with a firm bass line in a reading that from the first felt grounded in field and forest rather than wandering among the moon and stars. The arrival of the hymn marked a new beginning, and the hymn itself was more rapturous than ethereal. Toby Oft contributed a magnificently Pan-like trombone solo, reassuring at first, less so on its returns. The first development started cheeky, with frolicking winds that grew unsettled as the windstorm approached and the trombone, now in C minor, offered little comfort. The second development brought a pastoral utopia that scurried and sang before lapsing into a sadness that the final trombone statement couldn’t quite dispel. Rakitina caught the ebb and flow of Sibelius’s continual tempo changes, maintaining tension, drawing the string melody out at the end before the darkling horns intruded with a suggestion of the trombone theme. In the final bar you could clearly make out the strings surging from B into a final affirmative, of sorts, C. Rakitina created a Seventh to cherish; the perfect encore, had time permitted, would have been Tapiola.

Jeffrey Gantz has been writing about music, dance, theater, art, film, and books for the past 35 years, first for the Boston Phoenix and currently for the Boston Globe.