In a previous blogpost, I noted down some ideas about the possibility that all of us are part of one big computer simulation. I am equally intrigued by theories of the human colonialization of the universe.
I am a biologist by training, and throughout my scientific career I was always interested in the effects of radioactivity on the human body; as a high school student I wrote a paper on this topic, and during my time in research I have worked with radioactivity in many shapes and forms. Towards the end of my career in science, I was a radioactivity safety officer and went through training at a nuclear research institute (perhaps an idea for an additional essay; although this topic is already touched on in many of my books).
By now you may realize one angle that I am taking when considering the colonization of space by humans. No doubt humans can survive in space, but cosmic radiation doesn’t get much attention in the concept of space colonization. Surely Luke Skywalker doesn’t seem to be affected by it.
The Earth’s atmosphere protects the creatures living on its surface, as it blocks most of the radiation from outer space. Traveling by plane at a high altitude for 18,000 miles translates to a radiation dose equivalent to a full chest X-ray. Astronauts who travel completely outside of the atmosphere get much higher doses. So high, that cosmic radiation is the limiting factor for the length of manned space flights. Pilots and astronauts risk cancer, cataracts, and other ailments; in addition, radioactivity has an impact on the immune system which affects many biological processes. Radiation always damages the biological system in the same manner: its energy causes the formation of oxygen radicals, which in turn attack the genetic material – the DNA. As a result, the DNA may “break”, and the cell will die. Or the DNA is mutated, and the information it contains is altered. This can affect the individual itself; or if the change happens in a sperm- or egg-cell (the germline), the next generation will suffer from this change.
Alas, most of the space happens to be completely free of atmosphere. And any artificial shielding against radiation would be tremendously bulky and heavy and doesn’t seem to be a realistic option, as the spacecraft would need to be massive in size and weight. Colonists living on the moon would be forced to live underground, beneath a thick layer of rock.
In addition, the distances to travel are huge, which adds to the radiation exposure. The next star (except for the sun) is some 24 trillion miles away. Theoretically, it should be possible to create a spacecraft that could fly relatively close to the speed of light, but even then, the next stars would take dozens if not hundreds of years to reach. Reaching an inhabitable planet may take much longer. During that time astronauts and their families would collect many mutations in their cells or in the germline.
Add to that the effects of weightlessness on the human skeleton and body… through evolution, the human body was optimized to survive on Earth, at gravitation of 1g, and at the level of radiation that we receive day by day. Actually, if we could travel back to the age of the dinosaurs, there is a chance that we wouldn’t be able to survive on our own planet due to the higher concentrations of carbon dioxide and oxygen that existed at that time. Compare this to the extreme hostility of outer space or a distant Earth-like planet.
Humanity’s chance to conquer space indirectly is bigger. Self-replicating, intelligent, and evolving robots and machines, created by humans would not need oxygen to breathe, they would be immune to the effects of radiation, as illustrated by the space probes that are still sending valuable information, after dozens of years, from the rim of our planetary system.
Likewise, the chance that any extra-terrestrial visitor to Earth would be an organic organism is slim. Probably, such a visitor would either be a very primitive, highly adaptable lifeform or, much more likely, a robot or a machine (also see my short story: “The Exploration of Planet #17824540930“, and my upcoming novel REBOUND).
Still, technology progresses. Revolutionary new ways to travel the vast distances of space could be discovered, or intracellular DNA repair mechanisms might be developed, to „immunize“ man against radiation, These are at the moment not on the horizon, but who knows? Until that time, humanity is by and large confined to our single, beautiful home: Earth, and we should focus on protecting this beautiful place as well as we can.
Find out more about the exploration of space in my books.
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Originally posted 2019-03-09 21:08:00.