Cosmic!

Only by accessing the very earliest state of the Universe can we hope to find an explanation for the asymmetry, fundamental to our experience, according to which we only ever perceive time as moving forwards. Physical laws have an inherent symmetry that permits them to operate either forwards or backwards through time; yet we observe all physical processes progressing relentlessly towards an increase in entropy, the gradual degeneration of order.

For every action, there is an equal and opposite reaction. When you light the blue touchpaper on Guy Fawkes night, the force goes downwards and the rocket goes upwards. But gravity tugs rockets, apples and everything else downwards at a rate of roughly thirty feet per second per second, so to climb out of gravity’s well, and make it into freefall in orbit, a rocket has to get up to a speed of more than five miles per second – ‘escape velocity’, it’s called.

The more we learn about ourselves and the universe, the more we appreciate that aliens probably won’t just be humans with longer limbs and waving antennae. How do you communicate with a planet-sized slime with ESP that eats electricity?

We think of aliens and immediately cut them down or up (or some other inconceivable dimension) to our size. They can be bigger or smaller, their heads huge, their eyes bulbous; they are usually humanoid, occasionally reptilian, but they are always recognisable as variations on the theme of life on planet earth.

In Ireland we don’t need aliens; we already have a race of higher beings with strange powers who gaze deep into our eyes and force us to have babies against our will. We call them priests.

Mars shimmers in the night skies above the south-western deserts like something projected onto a black screen by a collective imagination. It is variously a fabulous technical challenge, an extension of the American frontier and the locus for sundry utopias. The planet’s entire surface, roughly equal to the area of all Earth’s land-masses, has been mapped, imaged and imagined: it has, we might say, been appropriated

Perhaps, as Cixin Liu’s science fiction trilogy The Three-Body Problem suggests, revealing your presence to a hostile cosmos results in your inevitable destruction, so sending messages into space may be something no sensible civilisation would do. If so, we may come to regret the 2008 advert for Doritos transmitted by one of the most powerful radar systems on the planet towards a star in the constellation of Ursa Major.

After Cicero, other Latin authors continued to use models of the cosmos to convey messages that went beyond astronomy; in a poem by Claudian, writing in the fourth century, Jupiter himself is baffled by Archimedes’ artefact: reducing the universe to something that could be held in human hands, it seems, is the ultimate act of hubris.

In 2016, a pair of scientists at the California Institute of Technology, Konstantin Batygin and Michael Brown, announced that they had discovered compelling evidence of an as-yet-unseen giant planet – Planet X – orbiting the Sun, seven times further out than Neptune. This isn’t the first time that astronomers have believed there may be nine planets in the solar system.

The universe is widely expected to collapse eventually, but might first dilate by a factor of one followed by a million zeroes. Its expansion is possible even if it has always been infinitely large. Infinitely many galaxies, scattered across infinite space, could keep getting further apart. Infinity being a large number, some of the galaxies could well contain exact duplicates of you and me. With sufficiently many typing monkeys, even Hamlet would get typed many times.

When the book begins, a notable astronomer could still look up at Mars and be convinced he saw canals, and a Martian race, thirsty, searching for water, desperate for our help. The women of the Harvard College Observatory were less romantic, and less wrong.

What was for traditional astronomy planetary ‘appearances’ explained by complex models, became for Copernicus a direct consequence of the relative speeds of the Earth and the other planets. Thus Copernicus stopped the heavens, and made apparent what had formally been taken to be a fact.