It is probably worth exploring if we actually have anything to fear before we get into the nitty-gritty about potential defensive strategies for our planet. While we can only know for sure if an alien species would be aggressive by actually meeting them, we can make some educated guesses about how such an encounter may turn out.

Some of the greatest scientific minds, like Stephen Hawking, have famously warned about not announcing our existence to the universe. He believes that bumping into extraterrestrial life would be devastating for our species and planet.

"If aliens ever visit us, I think the outcome would be much as when Christopher Columbus first landed in America, which didn’t turn out very well for the Native Americans," Hawkings said in a 2010 documentary for the Discovery Channel.

"A civilization reading one of our messages could be billions of years ahead of us. If so, they will be vastly more powerful, and may not see us as any more valuable than we see bacteria," he later qualified.

Whether intentionally or by accident, an alien species may wipe us out, or perhaps worse, consider us as a resource to be harvested. This, for example, is the premise of the First Formic War Trilogy in Ender's Game series of novels written by Orson Scott Card and Aaron Johnston.

In this series, the ant-like aliens called Formics do not consider human beings sentient since they lack a "hive mind". To this end, they begin to prepare Earth for a new colony. To this end, they mount an invasion but are defeated through various interesting tactics and extreme sacrifice.

While this is obviously fantasy, it does raise some interesting questions.

For example, what would aliens look like? Many thinkers in this field believe that our first contact with aliens will be with robotic probes or drones rather than living creatures. Similar to how we do not risk human lives on more extended space exploration missions, aliens may adopt a similar strategy.

This might be for a variety of reasons, but the time required for long journeys and investment in life support systems are chief among them. Yet other experts also suggest that such robots could be the aliens themselves.

"Because of the limits of biology and flesh-and-blood brains," Steven J. Dick, an astronomer and ex-chief historian for NASA has argued. "Cultural evolution will eventually result in methods for improving intelligence beyond those biological limits," he added.

Robotic aliens are also more likely to make such long journeys, as they will be far more durable than any kind of life we currently know.

However such aliens look, many experts have also warned that they will likely be unpredictable. If they are millions or even billions of years ahead of us in development, the outcome of meeting them may not be in our favor.

It is quite likely they'd be capable of some aggression, as this kind of behavior is generally favored by natural selection, at least here on Earth. After all, a species that cannot fight to defend itself or hunt is less likely to develop the capacity for exploring the unknown and taking the risks of space travel.

On Earth, at least, predatory animals tend to be the ones who have developed problem-solving abilities. The same is probably may well be true for alien life.

It may also be the case that aliens, like our own species, have developed the capability for both extreme violence and peaceful compromise.

"We have good reason to believe that aggressive instincts will be present in extraterrestrials," astrobiologist Pushkar Ganesh Vaidya has written. "To what extent alien life can curb their aggressive instincts (or else they will possibly self-destruct) is anybody’s guess," he added.

There is also the possibility that humans could unintentionally spark aggressive actions from aliens. Since such a meeting would be incredibly tense, the chances of events spiraling out of control are quite likely.

This sort of scenario has been covered in various sci-fi works for many decades now, but we will never really know the outcome of such an event until it happens. enders

How could we fight off an alien invasion?

So, assuming that a visiting alien race may have less than peaceful intentions, what, if anything, could we actually do about it?

Let's take a look at some of the current thoughts on the subject.

Read more:

https://interestingengineering.com/how-to-stop-alien-invasion