Let us draw an arrow arbitrarily. If as we follow the arrow we find more and

                                                more of the random element in the state of the world, then the arrow is pointing

                                                towards the future; if the random element decreases the arrow points towards the

                                                past. That is the only distinction known to physics.

                                                                                                John Eddington, The Nature of the Physical World

On the morning of your 50th birthday I

was hanging in the sky

behind the sun

watching a band of light

widen ahead of me: dawn

a stacked ribbon of colors

at a visible angle to the perfect

Cartesian x-axis

of the vast Atlantic,

narrowing to indigo behind me

full flood of light imaginable

ahead, a sloping pink-and-orange sunrise

glimpse of time, I thought,

an orientation: from 33,000 feet

so easy to see

how west of me

is also slightly in the past,

it's yesterday where you are

night coming on you alone

in your time zone so far behind

and below, so close to sea-level

yes, we live

on a round planet

but of course time is not

the mechanical roll

of spinning round ball around

glowing round ball

which if reversed

would make perfect sense:

no, time's anisotropic,

(that pesky second law

of thermodynamics

obtains again)

but physicists love

talking paradox, so

umkehreinwand

means at the microscopic

level, time's symmetrical

the unsolved question is

why we can't see both ways

whether causality's

a quirk of consciousness

whether when I wake

to a stray memory

of our bodies configured

on the same

coordinate plane,

or when I work

to make a gift

out of recurrence

out of the turning and return

I am causing the past --

that early rising to duct-tape

a poem to your door,

that across-the-floor pounce --

every year the urgency

of our so-young selves

increased by energy

put into the system later: delta Q, rising heat,

a physicist could play

with that notion