“Theories of Time and Space” is a poem of 20 lines configured in a series of 10 couplets. Although the couplets are arranged intentionally, there are no set metrical constraints or rhyme schemes used within the piece. Trethewey also does not use much sound play within the poem. The lines are all roughly the same length, but the number of stresses and syllables varies line by line. Formally, the poem is free verse, despite its use of consistent line and stanzaic lengths. Instead of metrical constraints, Trethewey relies on punctuation in the form of either enjambment or end-stopped lines to give the poem a sense of movement.

The poem’s numerical arrangement of 20 lines, divided into 10 couplets, implies some sort of mathematical evenness that speaks to the poem’s references to scientific theories of “time and space.” Traditionally, couplets rhyme in English poems; however, Trethewey’s use of couplets is more modern, divorced from traditional formal requirements. Many couplets in the poem are run-on or open, meaning the speaker’s train of thought carries beyond the first line of the couplet into the second. Moreover, the momentum of Trethewey’s couplets extends beyond the individual couplet itself.