Gazing Into the Abyss, Awed by the Emptiness Between Stars
A little daydream leads to curiosity, and curiosity leads to dizzying contemplation of the emptiness of space
I closed my eyes and let my thoughts stray far from where my body rests. I meditate like this sometimes, projecting surreal vistas against the inside of my eyelids.
I often envision alien seascapes, creatures great and small floating on the tides. Or dream of spelunking kilometers below the earth to find caverns made of colored quartz. This day, though, something made me curious about the utter emptiness of space.
Our planet is an oasis of matter in the vast emptiness. Every element we find here on Earth has been forged in the hearts of ancient stars which lived and died billions of years ago. Hydrogen combined to form helium, three helium atoms fused to form carbon, and so on. Only the rarest and most violent events, like the collisions of neutron stars, could have produced the heavier elements present on Earth. It is wealth beyond measure.
I imagine leaving Earth behind. Reaching 400 kilometers above the Earth, I am in the Interplanetary Medium. It was once called the aether. I still like the word even though it has lost its meaning. It suggested purity and divinity in a realm thought to be close to the gods.
Here, particles range in size from molecules to grains of sand. Some are perceptible if you look closely. Between 5 and 40 particles appear in every cubic centimeter of volume.
Continuing beyond the sun’s influence and the last solar winds is the Interstellar Medium. If I turn, the sun is still the brightest object in the sky, some 150 astronomical units away now. From here on, I’m unlikely to ever see another object, only light from distant stars. Here, density is measured in atoms, with between 0.1 and 1.0 hydrogen atoms present per cubic centimeter.
I turn away from the busier galactic core, where gas clouds could be orders of magnitude more dense, and venture into the Intergalactic Medium. The Intergalactic Medium is 500 light-years distant when traveling perpendicular to the disk formed by the Milky Way’s spiral arms. There is nothing here – a ponderous nothingness. One atom of hydrogen may be present in each cubic meter of space.
It seems impossible, but it becomes lonelier still. The Milky Way and its nearest galactic neighbors, the Local Group, are members of the Virgo Supercluster. Superclusters string together into the filaments that make up the spongelike structure of galaxy-containing space. Then, there are the parts in between.
Vast nothingness lurks between the filaments. Nothingness with one order of magnitude less matter than the already sparse Intergalactic Medium. About 75 million light years from Earth sits the closest void. As space stretches and expands, fewer and fewer stars are within the horizons of our observable universe. Yet the Great Voids grow.
It’s almost unpleasant to think about.
“At this horror I sank nearly to the lichened earth, transfixed with a dread not of this nor any world, but only of the mad spaces between the stars.” — H.P. Lovecraft
I opened my eyes feeling refreshed, though slightly disturbed by the feeling of insignificance in the vast universe.
I hope you found this brief journey around our local neighborhood within the observable universe interesting. Let me know in the comments.
