The 21st century marked a major milestone in the evolution of abstract art. While this form of art originated in the late 19th century as rejection of academic conventions, it has since traversed an incredible journey, becoming an integral part of the global art scene. The evolution of abstraction in the 21st century has been especially remarkable with its propensity to combine traditional themes with modern techniques.

Today, abstract art is a broad field with countless forms and styles being developed continuously. Notwithstanding, abstract art in the 21st century can be loosely categorized into three major trajectories: revolutionary abstraction, abstract illusionism, and lyrical abstraction.

Revolutionary abstractionists have shone a new light on rebellious movements in the art world. Artists such as Ellen Gallagher and Mark Bradford have boldly explored genres such as street and graffiti art, essentially revolutionizing our understanding of what constitutes ‘fine art.’ They have challenged not just the topical aesthetic prejudices, but also socio-political ones.

Abstract illusionism, on the other hand, showcases how artists have managed to create an illusion of space within the confines of a canvas, incorporating elements from sculpture and architecture onto flat surfaces. Through this style, artists including Olav Christopher Jenssen and Katharina Grosse have blurred the boundaries between reality and illusion, employing traditional principles of perspective in an abstract manner to create paradoxical spaces in their works.

A third dominant strand to emerge has been lyrical abstraction. It eschews rigid forms and structure, opting instead for a free-flowing blend of form and color that stirs emotions. Works by artists such as Julie Mehretu and Jason Martin have become the lyrical abstractionists’ voice, reflecting the emotional turbulence of the postmodern world through their eye-catching canvases.

Digital technology too has left its mark on abstract art in the 21st century. With advances in software and hardware capabilities, digital art has not only become more accessible but also more complex and diverse. Artists now utilize digital tools for everything from creating original abstract pieces to enhancing traditional media pieces, enabling a fusion of the digital and physical realms.

In tandem with the global socio-political climate, abstract art also shows an inclination towards highlighting previously marginal voices. There is a growing awareness to inclusive abstraction, featuring works by artists of various races, genders, and cultures. Artists like Ai Weiwei and Yayoi Kusama have used abstract art to voice their socio-political concerns, provoking dialogues on human rights, gender studies, and cultural complexities.

The abstract art of the 21st century, then, is not confined by the boundaries of the canvas but spills out to engage with the world. It has become a medium to communicate, disrupt, and enact, reaching beyond its visual dimension to engage the viewer’s emotions and intellect in unprecedented ways. Not merely a by-product of the artist’s emotion, the evolution of abstract in the 21st century has expanded its scope, offering an arena for societal critique, personal exploration, and aesthetic experimentation.

In conclusion, the evolution of abstract art in the 21st century is characterized by defiance, innovation, and inclusivity. Bolder in message and broader in medium, today’s abstract art stands as testament to artists’ unyielding spirit of questioning, exploring, and transcending the status quo. It is this resurgence that keeps abstract art relevant, engaging, and truly timeless. Despite its abstract nature, it has emerged as one of the most synthetic expressions of the contemporary human experience. And it is this diversity that truly encapsulates the evolution of abstract art in the 21st century.