> carrying out a crime while armed makes the penalty more severe.

Police are always armed when on duty. Just apply the same rules to them as to everyone else.

Essentially *all* Dollars, in a computer or in paper, are just representations of debt. When the Federal Reserve issues paper money, it's backed by Treasury bonds and mortgages. When banks make loans, the loan check is backed by the loan they just made.

> I don't believe that it is absolutely uncountefeitable. I did read the Wiki on it, but I don't think that any item digitally-based is safe. We are on /. after all ;)

Then you don't understand the central invention in bitcoin, an accounting ledger that is public and cannot be altered. In order to counterfeit some bitcoins, you would have insert a transaction into everyone's copy of the ledger, and also have a valid checksum (hash). Without it, every copy of the software will reject the data as invalid. The huge amount of specialized hardware thrown at generating valid hashes prevents anyone else from inserting a spurious one.

> I just hope it does not become publicly accepted. Can someone help convince me that bitcoin is the way to go?

Modern money, like the US Dollar, is just how we keep track of who owes something to others, or is owed something. Mostly the tracking is via bank ledgers, but occasionally it is on paper (as in paper money). Almost every dollar in existence represents a debt, either treasury bonds, mortgages, or other bank loans. Dollars make the debt easily traded in convenient units.

Bitcoin also uses a ledger to keep track. It's a public distributed one, but rather than being based on debt, it's based on work. All the balances are positive. This discourages a government from spending money it doesn't have, and banks from leeching off the rest of us, earning money simply because they create debt, instead of actual work.

Central banks have shown time and time again that they are bad at managing their money supply. Venezuela and Russia are two current examples, but there are literally hundreds of examples through history. Bitcoin's supply is managed by a software algorithm that releases new units at a known rate. It is on automatic pilot rather than the whim of fallible humans. I trust that more.

The big drop since 2008 is because solar cell production at that point exceeded silicon ingot needs for electronics. When electronics was the main demand, it was not worth making separate plants for "solar grade" silicon. Electronics grade is much more expensive, because crystal defects make computer chips unusable. They only make solar cells a little less efficient. Nowadays silicon ingots for solar panels is the dominant market. In this graph you can even see a rise in price as silicon got in short supply, followed by the crash as new solar-grade production went into operation:

http://costofsolar.com/managem...

Nope. They require a considerable amount of energy to create, that of all the mining rigs combined. The energy is used to update the transaction history (block chain). One of the transactions adds 25 new bitcoins to the history, but that event can't happen without finding a hash value for the block. Finding the hash value requires all the mining rigs to search for it, using energy.

> It seems more and more investors are losing faith in the very possibility of producing energy with fusion.

[citation needed]

This recent survey of alternate fusion projects says otherwise: http://nextbigfuture.com/2014/...

In the context of energy supplies, renewable means "there will be more supply tomorrow", i.e. the supply constantly renews itself. New coal and oil are not being produced at any appreciable rate. However the Sun is still fusing, and rain will refill dam reservoirs.

From a physics standpoint, yes, the Sun will eventually run out of fuel, but that's meaningless from a human standpoint. It will last a million times longer than we have had civilization.

> Maybe you hadn't heard, but there are people being paid to work out how to do all these things,

Yup, I'm one of them. I'm working on the idea of a "Seed Factory" ( http://en.wikibooks.org/wiki/S... ), which is a starter kit of machines which you expand by making parts for more machines. A 3D printer is likely to be part of the starter kit, but you need several others. The engineering R&D questions are what machines should be in the starter kit, what is the optimal growth path, and how do those vary with available raw materials and the desired end outputs.

The point here is sending a whole industrial plant into orbit to process an asteroid is much too massive. You want to bootstrap up from a minimal starter kit, and build the rest out of the asteroid itself, as much as possible. You won't reach 100%, some stuff will still need to come from Earth, but saving 85-98% of the launch weight (what we think is a reasonable goal) is still a huge advantage.

Today you need to launch a spool of ABS plastic, but one spool is less mass than a spare of every possible part that can break. It reduces spares inventory. This is also a very small first step towards making everything you need in orbit. ABS plastic is mostly Carbon and Hydrogen, which are both present in Chondrite type asteroids. The remainder is Nitrogen, which can be scoop-mined from the upper atmosphere. Combined you have all the ingredients for the plastic. You need other stuff in larger quantities in orbit - fuel, radiation shielding, oxygen, water, etc, so those will be produced first.

Now that they have a proof of concept, it is an obvious thing for researchers to try different pit sizes and patterns in order to optimize the efficiency. One thing they probably haven't checked yet is the effect of Sun angle. Most solar panels are on a fixed mounting. So the Sun lights them from different angles during the day. Therefore any patterning will have a different apparent pit spacing. I think there is a lot more to learn about this effect, but even small efficiency gains have dramatic effects. Most of the cost of a solar system these days is the "balance of system", i.e. everything besides the panels. More efficient panels means you need less of them, and therefore less installation labor and other overhead costs.

What you think of is wild speculation is just another day at work for a space systems engineer like myself. Going to the Moon was wild speculation in 1950, and a computer you could carry in your pocket was wild speculation in 1970. Fortunately progress doesn't depend on nay-sayers like yourself.

In orbit outside the Earth's shadow, you average 7 times the output for a solar panel, compared to the average location on Earth. That's due to lack of night, atmospheric absorption, and weather. If you can put that panel in place for less than 7 times the cost of a terrestrial one, you come out ahead economically to put it in orbit. Since launching stuff is expensive, you are more likely to reach that cost target if the panel itself can be made in orbit. Fortunately the average space rock is 40% silicon, which is what we make solar panels out of.

You are right that in 2014 it is cheaper to put the panels on Earth, but that may not be true at some point in the future.

No, the burn times are 110-465 days to return 200-1000 tons of material, plus coast times between burns. You can find the calculations at

https://en.wikibooks.org/wiki/...

200-1000 tons is a reasonable goal for early mining missions. If your chosen asteroid is larger than that, you scrape loose surface material or grab a boulder off it. Entire larger asteroids would require bigger power supplies and thrusters, so are best left for later generations. 1000 tons is a lot, that's twice the mass of the ISS. And you can fetch that much back every few years with a single mining tug.

> There are things called lathes and other machine tools that can reproduce themselves.

Not unaided. Machine tools can indeed make parts for more machine tools, but they need a source of power, and a supply of stock metal shapes to do that (and eventually fresh cutting tools)

> The real question is how many of these kind of tools together with a good smelter do you need before you can be self-sufficient and keep making your own sets of tools out of raw materials?

We phrase the R&D question a little differently: What is the best starter kit, and best growth path from the kit to a fully expanded factory? We have a draft starter kit list at https://en.wikibooks.org/wiki/... , and it includes a lathe, mill, and press, which are basic machines, but there are several others in addition. The starter kit emphasizes flexibility by using attachments to do different tasks. The expanded factory can add more specialized machines as needed, since your starter machines can only do one thing at a time.

> it would be nice to get a set of these kind of tools into the hands of people in 3rd world countries

Providing starter kits for under-developed areas is one of the project goals.

> It is also something important to know about if you are planning on building a colony on Mars or the Moon,

If you can build 85-98% of your stuff from local materials, it dramatically reduces how much you have to bring from Earth. That has huge leverage on what projects are feasible. However, helping people on Earth is a more immediate and larger need. So space versions will be 3rd or 4th generation Seed Factories. The first generation design is for ordinary people right here on Earth.