In 2009, it seemed that the eclectic British band Muse had finally settled on a sound. That year’s album, “The Resistance,” was firmly squared in a softer pop-rock aesthetic and signaled a possible radio-friendly resting place for the band of a thousand genres. However, the crunchy guitar riff that opens their latest release, “The 2nd Law,” serves as an aggressive rebuttal: the four rapid-fire notes seem to shout, “We haven’t landed yet.”

This metal-edged riff is just the start of the experimentation on “The 2nd Law.” Throughout this curious new album, the self-described “trashy three-piece” tackles musical styles spanning 40-plus years, from the pantheons of pop, rock, and prog to the digitized world of today and imbues each with its own over-the-top energy. The result is a largely fun but uneven ride that finally shows the limits of Muse’s explorative abilities.

As on pre-”Resistance” releases, the band uses each track on “The Second Law” to channel a different musical style. “Survival,” for instance, is a piano driven rocker a la Queen—a band Muse frequently cites as a favorite—with overblown backing harmonies to match. Indeed, as Matthew Bellamy emphatically belts, “I’ll keep up the pace / And I’ll reveal my strength / To the whole human race / Yes I’m gonna win,” it’s not hard to draw a line to another pedal-powered race that Freddie Mercury sang about 30 years earlier. Bellamy can’t match Mercury’s lyrical prowess, but “Survival” manages to capture the operatic extravagance of one of his heroes.

Other tracks delve into influences less familiar to the group with varying degrees of success. “Follow Me,” while beginning beautifully with Bellamy’s emotionally charged vocals floating over a lake of flowing synths, shifts into an utterly jarring quasi-dubstep chorus that traps Bellamy’s voice in a wash of computer-generated fuzz. However, the dubstep additions are not always invasive. The wobbling bass actually adds a welcome imperfection to the minimalist electro-ballad “Madness,” one of the album’s finer moments. Everything seems placed just so, from the barbershop-quartet-style “ma-ma-ma-ma-madness” to Bellamy’s vocal soaring atop the justly deserved climax.

The band is far less successful in its forays into straight prog-rock. “Supremacy” is an attempt to mash bruising Zeppelin-like riffs with grandiose James Bond orchestration, but the angry rock sections feel abrasive, not exciting, when juxtaposed against the serene hum of the midsection’s snare drums and string pads. Bassist Chris Wolstenholme pens and sings a pair of tracks late in the game, and while they are fine pieces of progressive metal, his admittedly pleasing smooth voice lacks Bellamy’s intense vibrato.

In the end, it is Bellamy’s expressiveness that ties these disparate tracks together. While his performance is technically marvelous throughout, he is most successful when conjuring poignancy and passion, which he does to great effect on “Explorers,” a piano ballad and lament for the dying earth. There is genuine melancholy and even desperation when he sings, “Free me from this world / We don’t belong here / It was a mistake imprisoning our souls.”

“Explorers” is one of the several tracks that attempt to tie the album together thematically. Vague references to the end of the Earth abound, culminating in the two-part overdramatic finale “The 2nd Law,” a shifting soundscape that swells and projects paranoia through a newscast sampled on a loop. “New energy cannot be created and high-grade energy is being destroyed,” reports the processed female voice. The track then launches into demonically robotic dubstep. It is certainly intriguing, but after the shock wears off, the piece runs on fumes for its remainder, devolving into swelling and receding electronics and infinite echoes of the newsreel. It’s too little and too late of an effort to bring the album under one uniting idea.

The second law of thermodynamics explains irreversibility in nature and the inevitability of moving in a definite direction. Muse’s “The 2nd Law,” on the other hand, seems content to wander about the genre continuum. But while it is a mixed bag in terms of content and quality, it never loses its key component: energy. Maybe it’s better that Muse doesn’t settle into one sound, as its unpredictability and experimentation bring excitement to every new release.