First up was Beethoven’s Symphony No. 1, and to the layman’s ear, the Philharmonic breezed through it. To Alan Gilbert, the conductor and music director, it was choppy. For one, the bass section, bouncing through the second movement in 3/8 time, was too loud. In one part, the second violins were late coming in after a pause, and in the fourth movement the violins’ runs needed to be crisper. Everything was hashed out expertly as Gilbert shaped the symphony to his ear. They played through the whole piece once more for good measure. This was rehearsal, after all.

Next was Beethoven’s overture to Fidelio: a short, sweet, driving exultation that alternated between pastoral lulls and swirling dives and runs. While not full of flourish, the overture was joyous and exuberant nonetheless. Gilbert seemed pleased. Two down, two to go, the musicians stood up to reset the stage for Shostakovich.

Three to five times per month, the New York Philharmonic conducts an Open Rehearsal. For $20, you can, according to the playbill, “watch the New York Philharmonic at work, and see how a piece of music is shaped and polished by the conductor and the musicians.” As fascinating as this sounded, I scoffed when I read it, confident that I could never truly “watch the New York Philharmonic at work.” I sat there and thought, hadn’t they heard of the double-slit experiment, that staple of quantum mechanics?

In a double-slit experiment, a beam of light is passed through two separate slits in a board, and depending on the method of observation, the light will act either as a particle or a wave. It seemed to me that, in theory, I could never truly “watch the New York Philharmonic at work,” since the fact that I was there observing would effect a change in the orchestra’s playing and, moreover, determine the form it would take. Which form, though, was still unknown to me. Would it be the particle, which is defined by having mass, or the wave, which is defined by its ability to transfer energy?

At rehearsal, the atmosphere is casual and inclusive. The musicians and conductor all wear plain clothes, rather than their traditional tuxedos and evening gowns, and there is no assigned seating. People chat openly during the performance and the lights are never dimmed, so your focus is divided between both the orchestra and the audience. The presentation humanizes the musicians, reminding the observer that they, too, are imperfect bodies of mass, resembling the particle form.

In contrast, a proper performance is otherworldly and more resembles the wave form. The musicians wear formal attire and the disembodied voice of Alec Baldwin reminds you to silence your phone. The lights are dimmed, causing a natural hush to fall over the audience. There is a feeling of anxiety and excitement, even enchantment, in this shared breath—this lull before the music begins. The stage alone commands your attention, and from that focal point the music seems to emerge as pure energy.

I sat back and relaxed as Lisa Batiashvili, the soloist, readied herself for Shostakovich’s Violin Concerto No. 1. The piece began with a simple bass line evoking drama and deep melancholy, which, once the violin entered, receded to play shadow to the melody. After the mournful first movement, sharp, startling violin jabs opened the second, and the heat of the music was overwhelming. From that moment on, nothing existed but a stream of energy and emotion that emanated from the stage via Shostakovich, Batiashvili, and the Philharmonic.

The finale was Gershwin’s “An American in Paris.” In the first movement, glittering violins and brass plucked at the melody, springing forth and diving away in live stereo. The percussion, providing vital accents, led a subtle march, while even more brass and violins evoked the bleating car horns of Paris in the 1920s. During a melodic sigh before the bluesy romp of the second movement, it felt as if the audience would die of wistfulness.

As the final movement raced toward its soaring reprise of the second, and concluded with what could only be called a fantastic burst of sound, I realized the flaw in my subjecting the New York Philharmonic to the laws of quantum mechanics. Light, no matter how it is observed, whether acting as particle or wave, is still just that: light. The same holds true for the Philharmonic. Whether at a rehearsal or proper performance, Central Park or on tour; playing Gershwin or Beethoven, Bach or the Pops—in every mode of observation, the New York Philharmonic is always, inescapably, itself.