Robert Irwin may not have the most works in the most shows affiliated with Pacific Standard Time. But he’s arguably the most important artist in the Getty-sponsored initiative. Art in California, and around the world, would not look the way it does today if not for Irwin, who has been exhibiting his influential paintings, sculptures and installations for 55 years. It all started in 1957. Just after the 29-year-old had finished hanging his first solo show at Felix Landau Gallery, he got a good, clear look at his abstract paintings and knew, in his heart, that they were terrible: perfectly respectable in appearance but too arbitrary to satisfy his need for something fundamental, spot-on, no-nonsense. Since then, Irwin has made series after series of groundbreaking works, each defying expectations and expanding art’s possibilities by stimulating the senses, challenging the intellect and stirring the soul. Some are better than others, but none is gratuitous. The best compel you to zero in on the physical facts of your perceptions, whose riveting intensity gives way to a sense of expansive serenity. Kind of like magic, but with no trickery. At L&M Arts, nine new works show the 83-year-old artist at his best: coaxing phenomenal beauty out of little more than thin air while making every second matter. Each of Irwin’s pieces consists of 6- or 8-foot-long fluorescent light fixtures mounted vertically on the wall. The largest, “All That Jazz” and “Durango,” are made up of 27 evenly spaced tubes. Others include from three to 13 tubes, most set a few inches apart but some abutted. Over almost all of the industrially produced lights, Irwin has slipped synthetic gels, up to 13 per tube. Their various tints cover an impressive spectrum, ranging from turquoise pastel to toxic copper, light-swallowing gray to clotted-blood red, and smoky citrus to a kinky symphony of unnatural greens. Vertical bands, custom painted on the gels, add to the complexity of Irwin’s homemade rainbows. And that’s just the beginning. Each piece has four settings: 1) all the lights illuminated; 2) all off; 3) some on; 4) others on. You have to see the transformations in color, mood and atmosphere to believe them. And even then you might not trust your eyes. In every setting, everything matters: the space between the light fixtures, the light fixtures, the gas inside the indirectly lit tubes, the light emitted from the lighted ones, the pinstripe-style gels and the shadows cast by the fluorescent lights, the gallery’s overhead lights and the Southern Californian sunlight. Until now, Dan Flavin has had a sort of monopoly on fluorescent light in art. Irwin’s use of the material is more painterly, supple and sophisticated. It demonstrates that the world is big enough for both artists. And his art’s true competitor is nature, whose visual effects often pale in comparison to Irwin’s extraordinarily nuanced works.