Why bother is because bitcoin are more divisible than shares of stock, and have less transaction costs than buying and selling dollars or GLD shares on the market. The trader who maintains the GLD account balances for the users only has to trade the *net* amount of shares required by all the users put together, rather than each of them making a trade for small amounts. I'm not going to pay for coffee directly with my GLD shares because just the brokerage commission is about twice the price of the coffee, even if I was selling a fractional share (which you normally can't). But transfer rights to 70 millishares of GLD to the coffee shop is fine if the overhead is negligible.

Yes it is, hand holds, foot restraints, and outside they have bars for hooking safety cable clips to. Human muscles would be useless without something to push or pull against.

Not one person, but two people could do it. The "standard racks" on board the Station can mass up to 500 kg each, and are swapped out regularly with new experiments. The large square hatch is sized to fit one of those racks, but you need two people for enough control of the movement so it does not smash things along the way.

The standard racks are derived from earthly 19 inch equipment racks, with two of them side by side, and aircraft "seat tracks" are on the front to attach things to. Seat tracks are what the seats in an airplane are mounted to. They did not see a need to invent new things from scratch for the job of mounting hardware.

Imagine if you will, that bitcoins are used as a "transaction system" to transfer ownership of GLD shares (that's a NYSE traded trust that simply holds a lot of gold in a vault in London, $64B worth). To the user, they are holding gold, and the bitcoins are transparent to them, as they are just being used as the message system to change balances in accounts. To the extent users stay balanced, the GLD trader doesn't actually have to trade his GLD shares, just keep track of who owns how much.

The value of bitcoins in and of themselves does not matter then, as they are not held very long. You only need a method to price bitcoins in terms of gold for the duration of the transaction. Thereafter the account balance will be in GLD shares or ounces of gold. So there you go, shiny things traded by intangible data messages (bitcoin transaction messages).

Every 10 minutes a new signed data block is created, that includes transactions from that interval. It also includes the signature from the last block, forming a block chain that goes back to the origin of the bitcoin system. There are currently about 180,000 blocks, and the block chain data is currently stored on every user's machine. It's around 1.7 GB right now. Creating new blocks is what "mining" does, and miners don't need the whole block history, just the current transactions.

1.7 GB is not a big deal to store right now, so everyone gets a full copy. In the future, more dedicated systems will store the whole chain or they will truncate the early part of the active chain to an archive and only store the recent set on user machines. In other words, when the chain gets too big, store the first million blocks in an archive, and only keep the last 100K.

Not completely removed, they are just suspending enforcement, but still contacting a few very heavy users.

To give an example relevant to the original story, I worked for many years on the International Space Station. Note the International part. Nonetheless, when we had visitors from our foreign partners, we had to cover up our whiteboards and computer monitors lest they see some forbidden data. This being a piece of hardware occupied by foreigners most of the time once it's in orbit. Pretty silly, right?

The protozoan was heard shouting "Hey you young species, get off my pond!"

Only the simplistic single noodle stationary space elevator (devised in 1895 for gosh sake) needs Unobtainium for building materials. For a more practical design see this page in a space engineering textbook I have been writing (along with anyone else who contributes, but mostly me so far):

http://en.wikibooks.org/wiki/Space_Transport_and_Engineering_Methods/Space_Elevator

The short version is that both rockets and space elevators get exponentially more massive with increased velocity. Therefore if you split the velocity to get to Earth orbit between the two methods, they *both* are much less massive than either by themselves. Thus a Skyhook type elevator that provides 2.4 km/s has a mass ratio of 16 times the arriving vehicle mass using existing carbon fiber and reasonable design margins (2.8:1 on the bare cable strength).

The rocket coming from the ground performs the remaining 6.6 km/s ideal velocity, and has a 13% payload fraction assuming LOX/H2 propellant. The ideal velocity is 27% lower than an unaided Single-Stage-to-Orbit rocket needs to do, which accounts for the higher payload. The Skyhook has a landing platform at the tip which the rocket does a vertical landing on. When returning to Earth, the rocket merely drops off the landing platform, and now has to dissipate slightly less than half the kinetic energy as returning from full orbit, so the heat shield problem is that much easier.

Your comment makes the common mistake of Earthlings, that distance equates to cost. On Earth it does, because transport involves either rolling friction, air drag, or wave drag, depending on transportation method. In space none of these apply, so the cost of transportation is related to velocity change, and not distance.

Dead synchronous communications satellites are spread out in a 263,000 km ring around the Equator, but they are all moving at nearly the same velocity, the amount to match the Earth's rotation and make them synchronous, so gathering them up won't take much velocity change. Also, new electric thrusters are ten times as efficient as old chemical thrusters, and make a wider range of missions possible than before.

Some of the dead comsats are still functional, and just ran out of station-keeping propellant to keep them in a fixed location. The point of synchronous satellites is all the ground antennas don't have to move, cause the satellites stay in one place in the sky. Fixing those satellites just involves clamping on a new fuel tank and thruster pack, and you are good to go.

More advanced repairs would involve remote controlled robots, likely, to replace other items like worn out or broken solar arrays. Fixing internal failures, like the amplifiers for the downlink transmitters would need a hangar and humans given our current robot capability, so that level of repair will need to wait for lower cost humans in orbit. At the least, we can gather the space junk into controlled orbits so it doesn't breed more space junk by collisions.