Cold, dark and empty…

Being alone – closeted away – far from familiar things – makes me think more about the universe and my place in it.

Away from people and disturbances and the clutter of ordinary life, I turn my gaze upwards…up….up….up… and away!

There is a popular view amongst astronomers that human life is insignificant and nothing special or remarkable. Such views are usually made as a remedy against the historically inaccurate anthropocentric view that the earth is the centre of the universe and that everything revolves around us. Even the patterns of the stars in the night sky were held to have significance for human destiny (and judging by the Astrology columns in newspapers today – they still do). We now know that that is not the case. As if to move away from mankind’s anthropocentrism – we are now told, by scientists and astronomers alike, that human life is insignificant. That we; and all life, is just a chemical scum on the surface of the earth – and that the sun is just another star, in just another galaxy of 100 billion stars, and that our galaxy itself is just one ‘island universe’ in a sea of 100,000 billion island universes (galaxies) that make up what we call the universe.

But is this really true?

Are we really so unspecial?

To answer this question we must consider the universe as a whole and then compare our peculiar selves to it. We are made of atoms and matter – our planet is made of atoms and so is the sun and the solar system. But the truth is that atoms; and matter in general, is not that common in the universe – far far from common as we shall see and most of the universe is empty space.

Close your eyes and let me take you on a journey within your mind’s eye. I am assuming you are reading this on earth. In your mind’s eye, travel straight upwards a few hundred kilometres. Now you are in the slightly more typical environment of space. But you are still being heated and illuminated by the sun, and half your field of view is still taken up by the solids and liquids and gases of planet earth. A typical location has none of those features. So let’s travel a few trillion kilometres further out in the same direction. You are now so far away that the sun looks like other stars – a tiny starry pin-prick of light. You are now in a much colder, darker and emptier place.

But it is not yet typical…

…you are still inside the Milky Way Galaxy, and most places in the universe are not inside any galaxy. So let’s continue moving out farther until you are clear outside the galaxy – say, a hundred thousand light years from Earth. At this distance you could not glimpse the earth even if you built the most powerful telescope yet built by humans. But even at this distance the Milky Way still fills most of your view. To get to a typical place in the universe, you have to imagine yourself at least a thousand times as far out as that, deep in intergalactic space.

What is it like there?

Well, imagine the whole of space divided into cubes the size of our solar system. If you were observing from a typical one of these cubes, the sky would be pitch black and totally dark. You would see no stars at all. In fact the nearest star would be so far away that if it were to explode as a supernova, and you were staring at it when its light reached you, you would not see even a glimmer. That is how big and dark the universe is. And it is cold: it is at the background temperature of 2.7 kelvin (that’s 2.7 degrees above maximum zero), which is cold enough to freeze every known substance except helium.

And it is empty: the density of atoms out there in a typical place in the universe is less than one atom per cubic metre. That is a million times sparser then the space between the stars, and much sparser then the best vacuum that human technology has yet achieved. Almost all the atoms in intergalactic space are hydrogen or helium, so there is no chemistry. No life could have evolved there, nor any intelligence. Nothing changes there. Nothing happens. And the same is true of the next cube and the next, and if you were to examine a million consecutive cubes in any direction the story would be the same.

Cold, dark and empty.

That unimaginably desolate environment is typical of the universe – and is another measure of how untypical the earth, and life, and me, and you – are. So those that say we are not special in the context of the universe – are blinkered. We are special but only in a physical sense. If the above doesn’t fill you with awe and wonder and sheer incredulity – I don’t know what will. You – your life – your everyday ‘boring’ life – with all the accoutrements of family, work, holidays, watching Pop Idol on weekends, friends, chocolate muffins and children. Your everyday life of thoughts, and dreams and music and literature and weekends in the cinema and annoying friends. This is all – in the context of a typical place in the universe – very special.

Because a typical place in the universe is cold, dark and empty.

And our lives – your life – clearly is not!

Chao!

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