February 24, 2023
The sheer vastness of space has never been contested throughout history. The distance between planets, stars, galaxies, and galaxy clusters is difficult to comprehend for our minds. The nearest star to our solar system, Proxima Centauri, sits over forty trillion kilometers away. The distance is so great, most astronomers prefer to use the term “light years” to indicate the distance light travels through a vacuum in one year. With a new unit in mind, Proxima Centauri is over 4 light years away.
In order to travel any significant distance in space, an entity must be traveling at or near the speed of light, which serves as the universal speed limit. Albert Einstein showed the light speed limit by calculating that energy expended to accelerated particles increases as speed increases and would be infinite at light speed. Thus, it made sense for the only particles(or waves depending on the definition) capable of traveling at the speed of light to be photons or light particles that possess no mass. The reason why we are able to observe the early years of the universe is because the light emitted at that time traveled at a finite speed to finally reach observatories millions of years later. Interestingly, our ability to observe the universe’s creation may imply that the rate of expansion of the universe may exceed the speed of light. This topic may be explored in a future article.
Interplanetary travel may be solely facilitated through transportation via sub-light speeds as it is implied that beings undergoing interplanetary travel must possess mass. However, given that organisms(or perhaps anything remotely related to organic life found in other systems) have finite lifespans, it would be safe to presume that anything traveling into or out of our solar system must do so at such a speed.
This hypothesis renders alien invasions ever more deadly than science fiction could imagine, as world governments and the general populace would be given little time to react to any approaching spacecraft. Human satellites and other space-monitoring systems are made aware of any extraterrestrial activity through the capturing of light. Assuming invading spacecraft emit light, the window between detecting the light and the spacecraft reaching earth is completely dependent on the proximity to the speed of light at which the spacecraft travels. Additionally, were the spacecraft to emit light, the ability of earthly systems to detect them is also called into question.
Another important factor to be taken into consideration is time dilation. This phenomenon occurs when objects achieve high speeds(or high gravitational potential differences) and experience a relative time slow-down, a principle addressed in Einstein's theories of relativity. In a hypothetical light-speed vehicle, an individual would never even experience their journey as the period spent at light-speed would equate to nothing. If technology was capable of approaching the speed of light, space travel could very well be a possibility for both humans and aliens as biological aging for travelers would cease to be a major issue. Unfortunately, this does put humans at a vast disadvantage during an alien invasion because invaders could theoretically depart their crafts mere moments following takeoff from their home planet and be prepared to commit any necessary measures to subjugate our world.
Although the prospect of an invasion seems limited to the realm of science fiction for now, if the Drake Equation proves to be true, incursions carried out by an extraterrestrial force remain an interesting possibility. If the position of Earth is located and the intelligent beings are armed with speedy spaceships, the stakes may be much higher than one might suspect.