The Limits of Communication in an Interplanetary Society

Instant, global communication has become a staple of modern life. While not all have access to it, all feel its consequences. At St Andrews, the large international student population depends on this ability to communicate with their families throughout the semester, even when they are thousands of kilometres away. This moment in time, however, is an outlier. Just as previous methods of communication took days or weeks to transfer information, so too in the future will this be the case. But how can we be so sure?

The universe has a speed limit. That limit is the speed of light, which is roughly 300,000 km/s. According to our current understanding of physics, nothing can go faster. While the speed of light may sound fast, it is agonisingly slow on a stellar scale. For example, a beam of light directed at Mars would, at its closest approach, take around three minutes to reach the red planet. At its most distant approach, it would take roughly 22 minutes. This, of course, neglects that whoever fired the beam would have to wait the same amount of time for the signal to return to the earth — leaving round-time communication sitting around 6-60 minutes. This effect only worsens the farther out one gets: the nearest star to our own would take light more than four years to reach.

Image: Wikimedia Commons

This means any communication taking place in space will be subject to lengthy delays and data limits, as the long distances make it difficult to store much in each message. If humanity does expand beyond Earth, communication between the different planets we inhabit may be severely limited. The populations on any planet can communicate as we do now with each other, but not beyond. This leaves human populations isolated in pockets throughout the solar system. 

This setup is much more reminiscent of bygone eras. The Roman Empire ruled the entire Mediterranean with little trouble despite the apparent limits to communication. However, their success was in part thanks to the ability to delegate power to local authorities. Any interplanetary government would have to do just the same. 

Travelling between planetoids also takes a lot of time. The National Air and Space Museum says it took the Apollo astronauts three days to reach the moon. According to NASA, it would take around seven months to reach Mars. Anything beyond Mars could take years. If any centralised state wanted to exert its control, it could take years before any force could be brought to bear. All the while, local authorities would be able to prepare. There is, however, one place in the solar system where a highly centralised state could operate relatively normally despite these challenges: The Jovian system of Jupiter and its four Galilean moons.

This system contains abundant resources, and the moons’ proximity to Jupiter and each other, combined with their low gravity, would make transit and communication easy. Thus, in the far future, if the solar system is populated with humans throughout and there is some central organisation to it all, it would likely be based in the Jovian system rather than Earth due to its more central location in the solar system. However, because of the aforementioned challenges, any society that arises within the Jovian system may only be able to control that system, as anything further would prove too taxing.

The combination of limited communication and travel would keep us with populations cut off from each other, inducing isolation, and resembling how civilisations lived in the past. This means that this moment of history, before we move beyond the Earth, will be the time when we are most connected as a species, as any time after will see us isolated from each other by distant stellar shores.