Tag Archives: gravity

Humans are such fragile entities

The more I read about the strangeness of our universe, the more I wonder if we, humanity, will ever colonise other planets. There’s not much chance we’ll settle on a diamond planet and I have to wonder how we’d go on many of the ‘earthlike’ planets already pinpointed. We are such fragile entities, we humans.

I’m in the throes of writing a sequel to my space opera Morgan’s Choice, which accepts the existence of political groupings of star systems into coalitions, federations and the like. Hey, I’m not special in that respect. Lots of SF writers have done the same thing, with great success – Elizabeth Moon, Jack McDevitt, Isaac Asimov etc etc and of course, Star Trek, Star Wars and the like. But how likely is it really?

Like all other animals we are closely attuned to our environment, more so than many of us actually realise anymore. In these days of electricity we can heat or cool our homes, spend half the night watching TV, or reading books, source food from all over the world so nothing is ever out of season, cross distances that took years in days. Yet we cannot escape the factors which shaped us.

I think there are five vital factors we will not easily overcome.

The first is our perception of time.

I use the word ‘perception’ advisedly, because time is something we measure for ourselves to put ourselves into context, if you will. But whether we think the sun is rising where we are, or setting, our bodies are built to expect a ‘day’ of twenty-four hours or so, because that’s how long it takes for the planet to revolve on its axis. What’s more, if we are suddenly wrenched from one time of day to another, as happens with long distance air travel, it takes time for our bodies to adjust. (It’s called jet lag)

Next is gravity, what we call weight.

We have evolved to suit the amount of force the planet exerts upon is. The advent of space travel and weightlessness has proved how important gravity is to our ability to function. Without gravity our bones lose density and muscles atrophy.

Then we move on to air.

Most of our atmosphere, what we breathe, is nitrogen, with twenty-three percent oxygen and a bunch of other gases in smaller quantities, including carbon dioxide. It also has a level of density. There’s more of it at lower altitude (see gravity). See what happens to mountain climbers if they climb before becoming acclimatised. Their bodies can’t cope. And if that mixture of gases changes past a certain level of tolerance, then what?

Then there’s temperature.

Humans exist in an apparently wide range of climates, providing they can find protection from the elements. But the range is actually not that wide in the scheme of things. This article in New Scientist speculates that global warming of only about 11° would render many places on our own planet ‘unliveable’.

The last factor is light.

Earth orbits a G class star which emits light towards the red end of the spectrum. We’re used to seeing colours in that light. If we lived on a world orbiting a cooler star with redder light, or a brighter star with more bluish light, we’d see colours differently.

Humans are adaptable. That’s why the species has been so successful. But even so, we’ve only ever had to adapt to the extremes of one planet. If humans are to venture to other planets I believe we will have two choices; terraform the planet into another Earth or modify the settlers to cope with the conditions. That would mean physically very different races of humanity occupying different planets. And here again, SF can offer plenty of examples. One that springs to mind is Moon and McCaffrey’s joint effort, Sassinak, where members of the Star Fleet have different body characteristics, depending on which planet they come from.

I admit I don’t take that route in my own writing. I simply assume all planets are earthlike, with only small variations in light, heat, time and gravity. I reckon I’m in pretty good company. Come on SF fans and writers, what do you do, what do you prefer?