>3. Space habitats are more convenient and cheaper to move between than leaving or even entering a gravity well like Earth's.
I have always thought that this would be a much more efficient way of living off Earth. Sci-fi wants us to believe that we can teraform planets. All they ever talk about are the atmosphere generators. However, they never address the reason the planet didn't have an atmosphere to begin with. To me, the research into generating artificial magnetic shields is the place to be. Generating those fields the size of a planet will be orders of magnitude more difficult than for smaller sized ships.
I'm sorry, what? Are you claiming we have created a livable atmosphere on another planet? Where? Which one? Are you talking about Earth? Humans did not create the Earth's atmosphere. We can barely "fix" the damage we do to it. "Fixing" is not creating.
He is saying that we are currently transformong the earth's atmosphere into a less hospitable one through a process of pollution / emitting greenhouse gases.
In my view, given that we can do this, it is not unreasonble to assume that one day we will know enough to be able to tweak a planet's habitability in the opposite direction, or in other words, make an inhabitable planet habitable.
Why magnetic shields? If the planet is large enough, you get gravity for free. If not, a magnetic field wouldn't help with atmosphere. (Or am I missing something?)
The magnetic shield has nothing to do with trying to keep people on the surface.
The Earth's magnetic Van Allen belts deflect most of the sun's nasty radiation streaming at the planet. These belts are created by the molten iron core of the planet. Mars no longer has this magnetic shield, and the sun's radiation burned off the atmosphere. If we generate new atmosphere, it will just get burned off again unless we can generate some way of deflecting that radiation.
That still doesn't solve the radiation problem(at least on mars). What's the point of colonizing Mars if we'd all have to live underground anyway? Might as well try doing that on Earth(or the Moon) first.
Building habitable structures on a planet's surface is not the same as making a planet's entire environment capable of supporting humans. That's the point of teraforming which was the point of the comment.
I have always thought that this would be a much more efficient way of living off Earth. Sci-fi wants us to believe that we can teraform planets. All they ever talk about are the atmosphere generators. However, they never address the reason the planet didn't have an atmosphere to begin with. To me, the research into generating artificial magnetic shields is the place to be. Generating those fields the size of a planet will be orders of magnitude more difficult than for smaller sized ships.