“The Asgard would never invent a weapon that propels small weights of iron and carbon alloys, by igniting a powder of potassium nitrate, charcoal and sulfur.”

—Thor, Stargate SG-1, “Small Victories”

To be fair, human beings have been to space as well and routinely get trounced by something as primitive as a mosquito bite.

Maybe the UFOs were built to withstand alpha-gamma-laser-magma-pulse rays, not our primitive projectile based weaponry!

The Road Not Taken [1]

A premise I was skeptical with but utterly fell in love with once I read it.

[1] https://www.eyeofmidas.com/scifi/Turtledove_RoadNotTaken.pdf

You know when you’re playing with a little kid and they fake punch you, and you dramatically go flying across the room and they laugh, they’re proud of themselves, and you laugh? Yeah the aliens playing that game with us right now.

As we've seen with our space probes, its difficult enough to land something on another planet and have it survive, nevermind equipping it with any offensive or defensive capabilities. Maybe these aliens are in the same place. They can get the balloon here, but just barely, and they're watching in dismay as their work get dismantled.

Utter nonsense. This would be a FTL alien civ. A civilization with many orders of magnitude more energy available. And manufacturing capabilities. And AI. And many other things. They’re not gonna send a stupid balloon. They’re not going to care about a balloon. It’s inconceivable that a civ could get here and not also have the ability to manufacture such basic technology on an enormous scale very easily.

> this would be a FTL alien civ.

Why FTL? or any of the things you list. We are already looking to fly tiny probes past alien exoplanets with Breakthrough Starshot.

Breakthrough Starshot is about sending a couple grams of tech on a multi decade journey. We are very far from having the tech to do this. You’re right. They don’t technically need to be FTL capable. But the rest of it remains. You’ll need an immense amount of energy move this far.

If you can get balloons into earth safely, you can also just pelt the planet with big chunks of metal at speeds more deadly than nuclear explosions.

It seems inevitable that eventually someone in a different dimension would find a way to start crossing dimensions, and start a recon program to report back on "good" dimensions.

Maybe they had no idea that was a thing. A super advanced species that either never considered it or was phased out so long ago the knowledge was lost. They’re just up there watching and freaking out a bit.

Its not a balloon though, and for all we could know they put up a fight and the US is keeping it classified.