David Kipping

You'd have to bound it into that orbit, but then you could use the entire Sun as your telescope.

With that kind of capability, you could image planets to kilometer-scale resolution from afar.

That really makes you wonder.

I mean, if we can conceive, maybe we can't engineer it, but if we can conceive of such a device,

what might other civilizations be currently observing about our own planet.

And perhaps that is why nobody is visiting us, because there is so much you can do from afar that to them, that's enough.

Maybe they can get to the point where they can detect our radio leakage, they can detect our terrestrial television signals,

They can map out our surfaces.

They can tell we have cities.

They can even do infrared mapping of the heat island effect and all this kind of stuff.

They can tell the chemical composition of our planet.

And so that might be enough.

Maybe they don't need to come down to the surface and do anthropology and see what our civilization is like.

But there's certainly a huge amount you can do, which is significantly cheaper to some degree than flying there, just by exploiting cleverly the physics of the universe itself.

It depends on what information you want.

If you want to know the chemical composition and you want to know kilometer scale maps of the planet, then you could do that from afar with some version of these kind of gravitational lenses.

If you want to do better than that, if you want to image a newspaper sat on the porch of somebody's house, you're going to have to fly there.

There's no way, unless you had a telescope the size of Sagittarius A star or something, you just simply cannot.

collect enough light to do that from many light years away.

So there is certainly reasons why visiting will always have its place depending on what kind of information you want.