Merchant displays QR code on their Point of Sale device, or prints out a sales slip with the same code. User snaps a photo of it with their smartphone. Bitcoin app on phone decodes it, and sends payment to the address specified. Merchant sees the transaction show up on his device, and hands over the item. If the store has no cell reception, they need to move to a better location.

That is only true for Konstantin Tsiolkovsky's 1895 space elevator design, which is seriously out of date. A segmented elevator is perfectly feasible with current carbon fiber. This uses a small one in low orbit, and another small one in GEO. You use orbit mechanics to transfer from one to the other. The combined cable length is 50 times less than the original version. That makes it more economical, less exposed to impact damage, and able to be built incrementally.

Unfortunately, the only pictures you see in media articles are of the 1895 concept, so that's the one people always think of. We need to get public perception out of the 19th century.

A bigger rocket won't do that for you. A starter factory that can self-expand to a diverse production capacity will. Put one in Earth orbit that mines returned asteroid rock, and spits out fuel, habitats, and *another* starter factory. Send the second one to Phobos, and spit out fuel, habitats, and a *third* starter factory. Land that one on Mars, and remote control it from Phobos, and start building your colony. When enough stuff is ready, send the people down.

Being able to produce fuel and habitats at multiple locations on the way to Mars has a huge impact on the cost per ton and per person. A bigger rocket get you more tons to orbit, but what you really want is *smart tons* of payload, that reproduce many times their weight in orbital outputs.

The owners of corporations are protected against unreasonable searches of their private business information, just like sole proprietors, or citizens in their data at home. As agents of the owners, corporate officers are the ones who should demand to see a warrant before granting a search.

> Getting rocket software right is difficult precisely because there is no way to do a live test.

As someone who tested software for the Space Station, there is, but it's very expensive, and seldom done. In addition to the other SQA methods mentioned, we had a simulation & test lab next to the clean room where the actual modules were assembled. We simulated all the inputs to the flight computers as if the rest of the Station was there, and flying, including testing all the possible fault conditions. That meant running hundreds of test sequences for each computer box. Before we got to the flight hardware, the simulations were run with isolated copies of the onboard computers in the lab. As a result, the test group was three times the size of the code group, and I haven't heard of critical failures in the fight software.

> When you give everyone guns

The U.S. has approximately one gun per person, including children (https://en.wikipedia.org/wiki/Number_of_guns_per_capita_by_country). They are not evenly distributed, but to a first approximation we already reached the "everyone has guns" level.

> a powerful magnitude-8.8 earthquake

As opposed to a weak magnitude8.8 earthquake?

> 2) The electricity companies are not under any obligation that I know of to take your electricity.

They are in locations where the utility regulators require "net metering". In a fair situation, the homeowner still pays a line charge, to cover line maintenance and provisions for current flowing backwards through transformers, and not overloading the lines in times of high output. Then they pay and earn fair per kWh rates (which may be different and vary by time of day) for power used and generated.

> 4) The cost of taking your crappy, varying pittance of power

Is nothing like the way you describe it. Unless surplus solar is a majority of the power on a distribution line (the line that goes from the substation to houses), it will simply go from your house to some other house on the line. The utility then pushes the difference through their substation to meet the remainder of the demand. They already have to handle varying demand on the distribution line, since demand varies all the time in normal use. Only if solar were more than what is needed to power the solar houses *and* everyone else on the distribution line, would the utility need to make provisions at the substation for running power to other substations.

http://spectrum.ieee.org/green...

"15 November 2012—Glass panels on rooftops and hurricane force winds don’t sound like the greatest of combinations, but solar power companies say their customers’ rooftop installations stood up very well to Hurricane Sandy’s onslaught."

Suniva panels are rated for 200 MPH winds ( http://www.suniva.com/document... ). The rest of the house would likely blow away first.

Solar Thermal, coupled with PV, Wind, Hydro, and energy storage will work. There is no requirement that only one kind of energy source be used to satisfy the demand curve. A current example is the Ivanpah solar thermal plant, just west of Las Vegas. They didn't bother putting in any storage because Boulder Dam, just east of Las Vegas, is on the same main power line. So whatever power Ivanpah puts out, just means more water behind the dam can be saved for other times.

Ivanpah also has natural gas backup. Once you already built the field of mirrors, boilers, and generators, adding natural gas burners is a small expense. The turbines don't care if it was the Sun or natural gas that generated the steam.

As far as storage, every electric car comes with a battery. If your car was fully charged up at work from a solar-panel covered parking lot and building roof, you can use part of that charge to feed your house at night. Buying a storage system by itself is expensive. But if you already bought a big battery for your car, not so much. There is a reason Elon Musk runs both Tesla and Solar City. They are complementary technology.

Due to copy/paste error, the 176% should read as 17.6%, and 657% should read as 65.7%.

"Many manufacturers currently give a double power warranty for their products, typically 90% of the initial maximum power after 10 years and 80% of the original maximum power after 25 years. Applying the same criteria (taking into account modules electrical performance only and assuming 25% measurement uncertainty of a testing lab) only 176% of modules failed (35 modules out of 204 tested). Remarkably even if we consider the initial warranty period i.e. 10% of Pmax after 10 years, more than 657% of modules exposed for 20 years exceed this criteria."

Thus nearly 2/3 of tested panels lost less than 10% of their output after 20 years. Your number for effective lifespan is way off.

Source: http://onlinelibrary.wiley.com...

The Government refers to one of the sides of the case Jewell v. NSA ( http://www.uscourts.gov/Multim... ). The plaintiffs (Jewell et al. as representatives for all US citizens unlawfully spied on) allege that the US Government as a whole by means of their Terrorist Surveillance Program, operated by the NSA and other agencies, violated the Constitution. As a practical matter, "The Government" here are the lawyers representing the US Government, likely from the Justice Department, and whoever else in the Executive branch assigned to work on and review the case.

We will find out in about two years. The number of coins generated per block falls in half every 210,000 blocks, which is about 4 years. Two years is when the next halving is due. Half the mining hardware will become uneconomic to use at that time.

The technology that underlies bitcoin, data secured by a series of chained hashes, such that the hash for one data block is part of the data for the next, enables a secure record keeping system for electronic data. Any change to past data, whether from errors or malicious tampering, is detectable because re-hashing the contents of a data block will give a different result than the one stored in the next block.

This is highly useful for a financial transaction system, the first application bitcoin represents. But secure digital record keeping applies to any kind of data whatsoever, and the applications are much wider than just digital currencies. To give one example, it can ensure the integrity of an operating system against malware. The original OS distribution and updates are encoded as a series of data blocks with chained hashes. Anything that is not supposed to be there would invalidate one or more blocks, and thus be detectable.

Corporate scrip (i.e private currencies) is a trivial application by comparison.