> I guess it might be possible to make composite materials by 3d printing

They already do that. It's how Boeing builds airplanes these days (I used to work at Boeing) - https://www.youtube.com/watch?...

The carbon fiber/epoxy tape is rolled out in layers, heat set to stick in place, then the finished part is baked in an oven to finish curing. And the strength exceeds that of metal, which is why they are building their latest jets mostly out of composites - it saves about 20% in fuel burn from being lighter.

> Peer to peer works for software, but it doesn't work all that well for physical goods.

I aim to prove you wrong. Feel free to follow our project and stay in touch for updates.

> not so much with tires - or shoes.

On the contrary, I've made shoes, from scratch. I used to do medieval re-enactment as a hobby. Since you can't buy the stuff we use at Wal-Mart, we mostly made our own. To make a custom shoe pattern, you can stick your foot in a plastic bag (wearing socks as appropriate, and crumpled paper to fill in toes, etc. Wrap the bag with masking or duct tape, mark where the seams go, and carefully cut it off your foot. The flattened pattern pieces are then used to cut out the leather.

The high tech method would involve using a 3D scanner on your feet, translating that into a pattern, and laser cutting the pieces, but at the end you still probably need a human with a shoemaking machine ( http://img2.allbrands.cc/image... ) or to hand sew it, because shoes are odd shapes and soft materials, which are hard to automate.

Would you trust automated production of lumber and concrete? Those are the first two products we are working on, because with those you can make a significant percentage of a building. Car tires are actually pretty high tech (there's a Goodyear plant a mile from where I live). They are a composite of rubber, synthetic fiber, and metal, all of which gets molded and baked into a monolithic unit.

> And that's without pondering whether we'll ever get a 3D printer that can print all those things that require so many different characteristics

You have missed the concept of distributed peer-to-peer commerce alluded to in the summary. You will not have a single machine that can make everything, but access to many different machines across a network, one of which might be yours. Shapeways (http://www.shapeways.com/) has the centralized version of this already. They have a building full of a bunch of 3D machines that can handle about a dozen different materials, but they only have one location.

Makerspaces are community organizations that have multiple tools and machines, shared among their users. There are more of those, in various cities. The end point will be many such local workshops, plus individuals who have their own machines, and all of it linked into a network that can produce whatever you need. I'm starting up such a project, where besides making end products, the factory also makes more of itself ( http://www.seed-factory.org/ ) ( http://en.wikibooks.org/wiki/S... ) . It's not fully self-replicating in the sci-fi sense, it requires people and outside supplies of parts and materials, but it is capable of growing.

Apparently roll a d20.

Actually, since Oculus is getting about 1% of Facebook's stock as part of the deal, Carmack (and the other Oculus owners) now *own* a chunk of Facebook.

The other way to spin this story is "Oculus buys 1% of Facebook for a half-finished VR headset."

Pretty easy, since a complete record of every bitcoin transaction ever is available for every user of the software. It's called the "Block Chain", where a "block" is a set of transactions that have a hash generated to validate the contents, and they are chained by also including the hash of the previous block as data in the following block. Thus any changes (data corruption or malicious) become evident by re-hashing the block and comparing it to the value stored in the next one.

The Block Chain is shared across a peer-to-peer network among running copies of the software, so that everyone gets a constantly updated copy as new blocks are added.

Your terminology is incorrect, though. Bitcoins don't have transactions. Addresses have transactions, whose amount is measured in bitcoins. But the addresses are indexed for the Block Chain data, and it is fairly trivial to look up all the transactions for a given address. There is even an online website you can look it up without having to download a full copy: https://blockchain.info/addres... (these are transactions for the address in the last part of the URL).

You just need to know the addresses associated with the "found" 200,000 BTC.

> Do comets count?

The distinction between comets and asteroids is no longer scientifically valid. By composition, comets and outer Solar System bodies are the same. Comets just happen to have orbits that get so close to the Sun they evaporate water and other ices and create a tail. There are intermediate bodies in the asteroid belt and out to about Saturn that give off just a little outgassing, but not enough to create a full tail. "Dead comets" have comet-like orbits, but no longer have any volatiles to outgas, and so are indistinguishable from asteroids otherwise.

The modern way to distinguish these small Solar System bodies is:

- Never got close to the Sun, and still has all the volatiles (water, methane, etc.)
- Sometimes gets close to the Sun, and still boils off volatiles when it does
- Has spent too much time close to the Sun, and has been baked dry.

Those are verbose descriptions, so I like to borrow from steak terminology and call them Raw, Still Juicy, and Overcooked.

In fact, actual astronomers refer to all the solid objects that orbit the Sun as "planets". The come in three sizes: major planet, dwarf planet, and minor planet. The IAU Minor Planet Center ( http://www.minorplanetcenter.n... ) tracks all those things otherwise known as "asteroids".

The exact dividing lines are:

Major Planet - Round, and massive enough to have "cleared" it's orbit of other large object (it's the dominant mass in it's orbital region)
Dwarf Planet - Round, but has not cleared it's orbit, thus Ceres and Pluto fall into this category.
Minor Planet - Too small to become round under it's own gravity.

As a note, the stuff that got "cleared" falls into three groups: impacted one of the other planets and got absorbed, kicked entirely out of the Solar System, or kicked into an eccentric orbit but not ejected. That last group is called the "Scattered Disk", and there are around 400 known objects in the category. They are separate from the Kuiper Belt, which is leftovers in the outer Solar System which have not really been moved in their orbits. There are about 1200 objects in the Kuiper Belt, inlcuing Pluto.

> but how to grow your own food?

People would move back to the country if cities become unsustainable. What method to produce food depends how far civilization collapsed. Steam powered farm tractors are pretty low tech, and abandoned cities would be an abundant supply of steel to make them out of.

> The problem is that the natural resources that we are consuming now are NOT renewable (fossil fuels, minerals, metals). Once they are gone, they are gone, and there will be no recovery.

It's not like the atoms of carbon, silicon, and iron vanish when you make a product out of them. There are already bio-engineered microbes that can take sunlight & CO2 and emit new hydrocarbons (diesel and ethanol). Reprocessing other materials just takes enough energy, and there is no shortage of that as long as the Sun shines. 10,000 times as much Solar energy arrives at the Earth as we use to run our whole civilization. We only need to use a tiny fraction of that to keep things running.

This is already possible with something called "colored coins". Instead of the tokens themselves having value, they represent ownership of other things, like a share of stock or an ounce of gold. They can still be traded online, and divided into smaller parts, but additionally the holder of the colored coin can redeem them for the underlying asset. The "colors" terminology comes from each color being a different asset class. These yellow coins are backed by gold, these green ones are backed by dollars, etc. They can be freely mixed on a single block chain, as long as you have a way to tell the colors apart from each other.

> Bitcoin has no chargeback mechanism.

You are wrong about this. There is a built-in escrow function that returns payment to the sender if the conditions of the transaction are not met. Bank card charge-backs are mostly limited to 60 days, and assumes the conditions are met if there is no objection within that time. In addition to the built-in function, people can use escrow services who hold funds until the sender is satisfied. In turn, escrow services can make arrangements with merchants about holding time and amounts.

The thing about bank cards is you are paying for the charge back feature whether you need it or not. Bitcoin makes extra services "a la carte" - you don't have to pay for the ones you don't need.

> anything traded is 'currency'..

No, something generally accepted in the market as an intermediary is a currency. Direct trade (some of my stack of lumber for a dinner) is called "barter". Barter has the difficulty called "a coincidence of wants". You need people who both want what the other person has to trade. A currency simplifies this difficulty, in that I can trade my lumber for currency, then later find someone making dinner, and trade my currency for that. I don't have to find someone who wants my lumber AND is making dinner.

For a currency to be useful as an intermediary, enough people have to accept it in trade. In theory, anything at all can become a currency, but in reality only a few items become the currency of a given community because of the network effect. Whatever is most used tends to get used even more. Which items gain early acceptance depends on their features: inherent usefulness, durability, portability, fungibility, divisibility, scarcity, and others. Fish are useful, but not very durable or portable. Cattle are also useful, and reasonably durable, and portable because they are self-mobile, and in fact cattle were used as an early currency. But they are not fungible (not all identical units), and not very divisible until you eat them, so other kinds of currency with better features replaced them. Sand meets many of the features of a currency, except scarcity - there's not much point in trading for your sand, when I can go get my own. Gold is better in that respect - it's not easy to go get your own, so if you want some, it's easier to trade for it.

Gold is useful (you can attract women with it), and has all the other features except divisibility for small amounts, and portability for large amounts, so for a long time it was the best currency.