In answering “If aliens really exist, why don’t they visit Earth? Do they fear humans?”, at least we agree. They aren’t visiting. But why not?
I suggest because they are in a galaxy far, far away and light speed is just plain pokey.
Even though we want to go faster than light (FSL) for making cool Star War and Star Trek movies, the reality is that not only is light speed impossible, getting close to light speed is impossible. It would take infinite energy to accelerate to the speed of light.
Even if you could go as incredibly fast as, say, 1/20th the speed of light (highly unlikely), it would still take 800 years to visit the Trappist-1 system with seven Earth-size planets. It could very well be that Trappist-1 has no life. More likely we would have to go out a lot further, perhaps across the galaxy or billions of light years to other galaxies to find intelligent beings.
Those alien beings have the same problem we have. We both suspect the other exists, but neither will ever know for sure because the distance is too great and the speed of light is too pokey. All we can do is imagine.
I’m going to answer this and go beyond and explain a lot more.
Flat earth believers don’t fly to the underside of the earth and take pictures because, they say, there’s a dome over the whole thing, which is why we have a “wall of ice” to prevent us from getting out and walking over to touch it. It’s a convenient idea to avoid various dilemmas like the one you pose: flying over the edge to look at the other side. Here’s an image that illustrates their belief, showing the Earth, the dome, and the movement of the sun.
Please note, in this image below, the shape of Australia.
Notice, in this image, the sun is over Australia. This is a picture of what flat earth people think Australia looks like:
Let’s compare this image to actual distances. Below you can see Australia is actually 2,511 miles wide. You can drive it. There are roads.
Now in the image below you can see that Australia is almost as tall as it is wide using actual measurable distances.
So flat earth people believe Australia is much wider than tall, which is the only way they can depict Australia on their flat earth map. Below is what Australia actually looks like:
One of a billion problems with flat earth maps is they cannot account for the distortions that they see. This can only be rectified by using the spheroidal earth model.
So there you have it. The real reason they can’t fly underneath to see the flat Earth is that the Earth isn’t flat!