Readers of Tracy K. Smith’s third book of poetry, Life on Mars (Graywolf, $15), which won the Pulitzer Prize this week, had better be prepared to face some stark metaphysical questions. Is our universe “a house party,” as the title of one poem suggests, or a “primal scream,” as another would have it? “Is God being or pure force? The wind / Or what commands it?” Or might there be more than one God? “Maybe there is a pair of them, and they sit / Watching the cream disperse into their coffee // Like the A-bomb. This equals that, one says, / Arranging a swarm of coordinates // On a giant grid. They exchange smiles. / It’s so simple, they’ll be done by lunchtime.” Cosmically speaking, of course, we will all be “done by lunchtime.” An awareness of death permeates “Life on Mars.” Two of the longer poems, “The Speed of Belief” and “My God, It’s Full of Stars,” are moving elegies for Smith’s father, an engineer who worked on the Hubble telescope. The latter is particularly strong, making use of images from science and science fiction to articulate human desire and grief, as the speaker allows herself to imagine the universe

. . . sealed tight, so nothing escapes. Not even time,

Which should curl in on itself and loop around like smoke.

So that I might be sitting now beside my father

As he raises a lit match to the bowl of his pipe

For the first time in the winter of 1959.

Ron Padgett’s How Long (Coffee House, $16), one of two finalists for this year’s poetry Pulitzer, is also concerned with nostalgia and loss, but tonally it inhabits a different galaxy. Indeed, Padgett’s poems are so playful, self-mocking and eager to please that it would be easy to overlook their craft, not to mention the depth and sincerity of the emotions they convey. What animates “How Long” is the tension between the buoyancy of its language and the gravity of its subject, death, to which the poems obsessively return. The loss of friends and the aging poet’s own impending demise pervade the book, from the question half-concealed in the book’s title to the oddly moving meditation of the penultimate poem, “The Great Wall of China”: “Am I great yet? no I am smaller and smaller / and happier to be so, soon I will be only one chopstick tall,” Padgett writes, and a few lines later: “Perhaps at a certain age holiness slips in automatically / and says Just sit there and don’t say anything it’s alright.”

This year’s other Pulitzer finalist, Forrest Gander’s Core Samples From the World (New Directions, $15.95), is more radical, and it will strike many readers as the most forbidding of the three. It may also, in the long run, prove to be the richest. “Core Samples” presents four travel journals written as haibun, a Japanese form that alternates prose with haiku. These journals, which describe the poet’s travels in China, Mexico, Bosnia and Chile, are separated by poems written in a dense, dreamlike vernacular. The book is intelligently enhanced by the inclusion of striking photographs by Raymond Meeks, Graciela Iturbide and Lucas Foglia. The correspondences between these elements make for a complex reading experience punctuated by moments of intense beauty: “The world shifts / on a hairline crack. All last summer / you and I met for lunch in a clearing / we didn’t know the locals call / The Girl’s Grave.” Death again. But what really haunts Gander, who is a translator as well as a poet, isn’t so much death as the complexities of life: the frequently unknown stories that lie beneath and within the stories we tell. When he writes, “She too awakens the unknown inside him,” this reader, at least, can hardly resist the temptation to think that “she” is poetry itself.

Jollimore’s most recent book, “At Lake Scugog: Poems,” appears in the Princeton Series of Contemporary Poets.