Also missing: a folding bike. Very convenient for "multi-modal" transportation. Ride to the train, fold and stow overhead if the train is crowded, unfold and ride to destination. Raining? Into the trunk of a cab.

Mad Parent upward and onward!

Isn't gasoline derived from all natural ingredients? That means it's good for the environment. We all have to do our part!

Economic growth will be maintained for as long as is possible - it's in Civilization's DNA. Therefore, environmental and human costs will eventually be utterly disregarded, and all existing fossil fuels will be extracted and burned at the market's earliest convenience. Nothing anyone says or does will make the slightest difference.

John Ioannidis, a medical statistics researcher on a small island in the Aegean, leads a group that has done significant work in this area. Here is an article in The Atlantic about his work.

From the article: ". . . Ioannidis laid out a detailed mathematical proof that, assuming modest levels of researcher bias, typically imperfect research techniques, and the well-known tendency to focus on exciting rather than highly plausible theories, researchers will come up with wrong findings most of the time. Simply put, if you’re attracted to ideas that have a good chance of being wrong, and if you’re motivated to prove them right, and if you have a little wiggle room in how you assemble the evidence, you’ll probably succeed in proving wrong theories right."

"Unlimited economic growth" is utterly impossible. Fundamentally, as Tom Murphy points out here and here,

a) all activity requires energy, and
b) there are fundamental limits to efficiency, guaranteed by the second law of thermodynamics.

Read the article. Both of these facts together mean that continued growth is impossible. Even the most optimistic scenarios lead to absurd conclusions i.e. the energy needed for continued growth exceeds that available to a civilization which operates at the best possible efficiency, and which uses all conceivable resources within a spherical volume expanding outward at the speed of light.

In other words, all possible efficiency combined with all possible resources are not enough. Period. Growth must come to a stop, at some point.

But I'm not going to throw it away just yet . . .

I want me some Reggae Telescope!

Forces acting on the feet are transmitted to the rest of the body: we call this "standing up". This is true regardless of your frame of reference.

Centrifugal force is a pseudoforce, i.e. a force arising from the acceleration of a non-inertial frame of reference.

Gravity is also a pseudoforce - this is the fundamental premise of General Relativity.

The entire solar system condensed from the same rotating, swirling cloud. So the ratios of the elements are pretty consistent throughout. There do exist some differentiating processes, e.g. heavy atoms sink to the interior of planets, but the starting ratios for all parts of the cloud were the same.

The incoming stream seen by IBEX has a O/Ne ratio falling significantly outside of the range expected for gasses of solar system origin.

Yes, we'll adapt - the last time we were in such a situation we won the smackdown with the Neanderthals. We're survivors. But merely surviving doesn't mean we'll maintain the ability to launch and therefore allow life to survive in the longer term.

Yes, let the oceans eutrophy and there might be time for *one* more round of oil-making. That's an ugly way to get energy from the sun. If we are not able to find a way to lift life off the planet, then maybe the next sentient species won't either? Now is very likely life's only chance, so it is imprudent to assume another solution will bubble up before the oceans bubble off.

Good point. Short answer: the volatiles are leaking out the top, so Earth's air and water have a shelf life. Eventually, either the greenhouses on Earth would have to have exactly the same construction as the freely orbiting vessels, or the Earth would need to be terraformed.

Also, the ratio of sunlight available to outer space settlements to that available to the Earth, i.e. the area of a sphere 1 AU in radius to that of a circle 1 Earth radius big, is 550 million. That's 550 million times as much energy available, given enough time for construction. (Yes, such a sphere is not orbitally stable; 550 million is an upper limit.)

And yes, when the sun goes out all solar collection stops. But by then, with billions of years of experience in living in free vessels, the hope is that nearby red dwarf stars would be settled: they have life expectancies in the trillions of years.

And yes, the universe is running out of energy, or is going to be ripped apart at the sub-nuclear level, or is going to collapse back down into a singularity. Maybe all the protons will decay. But given trillions of years of physics research on a galactic scale, who can estimate the discoveries that might lead to a solution?

Bones cracking? A properly designed spinning vessel would provide centrifugal force that would be a perfectly good substitute for gravity.