Any vehicle that can cross interstellar space in a reasonable time also has enough energy to destroy a planet, simply by crashing into it.
So any alien race that can travel here could also drone strike earth and kill us all before we even saw it coming.
In fact, this makes it a prudent move to pre-emptively kill any civilization you notice, cause you can’t ever know if they would do it to you, before it’s too late. It’s the principle of Mutually Assured Destruction, without the Mutual part.
As for diseases, we’d have to meet them in completely closed-off chambers.
And even then, it’s possible that they emit strong x-rays to scan their surroundings, giving us radiation poisoning.
Or they use 200dB sonar, deafening us. Or the other way around, their bodies rapidly oxidize in an oxygen-rich environment.
So any alien race that can travel here could also drone strike earth and kill us all before we even saw it coming.
In fact, this makes it a prudent move to pre-emptively kill any civilization you notice, cause you can’t ever know if they would do it to you, before it’s too late.
Any vehicle that can cross interstellar space in a reasonable time also has enough energy to destroy a planet, simply by crashing into it.
Depends on the size of the craft. If it is only a few meters across, I think it would just burn up in the atmosphere before it even reached the ground.
Any vehicle that can cross interstellar space in a reasonable time also has enough energy to destroy a planet, simply by crashing into it.
So any alien race that can travel here could also drone strike earth and kill us all before we even saw it coming.
In fact, this makes it a prudent move to pre-emptively kill any civilization you notice, cause you can’t ever know if they would do it to you, before it’s too late. It’s the principle of Mutually Assured Destruction, without the Mutual part.
As for diseases, we’d have to meet them in completely closed-off chambers.
And even then, it’s possible that they emit strong x-rays to scan their surroundings, giving us radiation poisoning.
Or they use 200dB sonar, deafening us. Or the other way around, their bodies rapidly oxidize in an oxygen-rich environment.
This is basically dark forest theory.
It’s also really hard to do stealth in space, and so interception would be easy enough to pull off.
Depends on the size of the craft. If it is only a few meters across, I think it would just burn up in the atmosphere before it even reached the ground.
If it burns up in the atmosphere with relativistic speed, it burns up the atmosphere.
Relevant xkcd video: https://www.youtube.com/watch?v=3EI08o-IGYk
True, but damage still depends on craft size. At the really small end you’re basically just talking about a normal cosmic ray.