* Posts by Dani Eder

123 posts • joined 14 May 2009


Don't let banks fool you, the blockchain really does have other uses

Dani Eder

Re: Totally Niche

> it runs out of coins eventually

A bitcoin is divisible to 8 decimal places. If we use the last 2 as the equivalent of cents/pence, then the 21 million minable bitcoins supply 21 trillion "bits" (the name for a micro-bitcoin). That's equivalent to the whole world's M1 money supply in dollars/euro/pounds. Surely that's more than enough for a "niche" currency.

Bitcoin's best use is to transmit funds from place to place. So, for example, one business uses it for remittances from workers in South Korea and other Asian countries to their families in the Phillippines. The bitcoins are invisible to the customers, they put in local currency at one end, and get out local currency at the other end. They use it because the fees are much lower than Western Union or bank wires. Maybe remittances are a niche, but they're a $500 billion a year niche. International payments of all kinds are difficult and expensive. Since bitcoin is borderless and relatively cheap to transmit, there is a case for using it.

Watch it again: SpaceX's boomerang rocket lands on robo-sea-barge

Dani Eder

> I'd wager it's a pretty international workforce at SpaceX

You would lose the bet. From their job application page:

"To conform to U.S. Government space technology export regulations, applicant must be a U.S. citizen, lawful permanent resident of the U.S., protected individual as defined by 8 U.S.C. 1324b(a)(3), or eligible to obtain the required authorizations from the U.S. Department of State."

It's that way across the aerospace industry. Most space technology is classed as "munitions" because of ballistic missiles and spy satellites. So "export" is restricted, and that includes hiring foreign workers. It even applied to the Space Station program, which was international by design. Those of us at Boeing couldn't talk to our counterparts in partner countries. Stupid but true.

Reluctant Wikipedia lifts lid on $2.5m internet search engine project

Dani Eder

Re: " project costed at $2.5m"

If you look at their financial reports, most of it is salary related ($25 million/year) They own $5 million in hardware, and pay $2 million/year for internet service, so the core of running Wikipedia is pretty cheap considering the user base.

Bitcoin's governance bungles stain the blockchain's reputation

Dani Eder

> And what if the transaction does take place, but the record is lost?

The design of the blockchain prevents that.

When you create a transaction, you are saying send X amount of bitcoins from address A to address B. You sign it with your private key to address A, proving they were yours to send. It then gets broadcast to the network of 6000 nodes, each of which compares your transaction to the balance of address A, to verify you had enough to send. They also validate your signature and some other technical checks. If it passes, they add it to their pool of pending transactions. So at this point the transaction is stored in 6000 places.

Miners are also nodes, and see the transaction. They compete to find a "hash" (checksum) for a block of transactions, in order to win the block reward (currently 25 new bitcoins worth almost $10,000) plus transaction fees from the included transactions. Blocks also record the hash of the previous block, linking them in a chain (hence "blockchain"). When your transaction is included in a block, it is "confirmed", and removed by the network nodes from the pool of pending transactions. The new block is added to their copy of the growing blockchain. The transaction is still stored in 6000 places, but in the chain instead of the pending pool.

At no point can the record of the transaction be "lost", it's in too many places. It can remain pending if blocks are full and it never gets into one. If the pool of pending transactions gets too large, nodes can start dropping some to save memory space. In that case, your transaction was never completed. You can try again later, since the official blockchain shows you still have the funds in address A.

The current block size limit is 1 Megabyte, which allows about 2500 transactions per block, and blocks average one per 10 minutes. In theory that allows 360,000 per day, and lately there have been 220,000 per day getting processed. The argument is over how to increase capacity, since we are getting close to it. The simple answer is to raise the size limit, but that increases bandwidth, block transmission time, storage requirements, etc. An alternative is to move parts of transactions (the signatures) or entire swathes of transactions (side chains and such) off the main bitcoin chain, and only record the important bits. For example "this transaction on the main chain summarizes 1,024 smaller transactions on side chain Z".

Everyone involved wants bitcoin to grow, and it is obvious capacity needs to increase. They disagree on *how* to do it.

Dani Eder

Re: So, let me see . . .

> fairy money scheme

The Bitcoin network consists of an astonishing amount of custom hardware chips, 6000 active network nodes, and, more importantly, millions of users who generate 220,000 transactions a day. The bitcoin unit is a token marking some value being moved, in the same way a shipping label is a token marking a package being moved.

The token marks a fractional interest in the value of the network, since there is only one blockchain and all the tokens and which address controls them resides there. It doesn't have value in itself, but then neither does an entry in a spreadsheet, or in the bank's database for your account. It's what value those data entries represent and can mobilize that matters.

> Until I finally get a working flamethrower,

Amazon sells those, and you can pay for them with bitcoins :-) (via ShapeShift card)

Investors furious that Amazon only made $482m last quarter

Dani Eder

Overall earnings are less than 0.6% of sales for the year, and none of that was from their main business as a web retailer. AWS generated more profits than the total for the company. That means retail sales actually lost money on the year.

If you are an *impatient* investor and only look at quarterly results, yes, that would be a bad result. But I look at it as Bezos is playing the long game. He's in the process of displacing a big chunk of retail storefronts. Once he has skimmed off a segment of that huge market, *then* he can stop spending on growth and return profits.

Dani Eder

Re: Direction

From the numbers presented, Amazon is a non-profit web retailer. They make all their profits from cloud services. The old joke about "losing money on each sale, but make it up in volume" is actually true for this company.

Getting metal hunks into orbit used to cost a bomb. Then SpaceX's Falcon 9 landed

Dani Eder

Re: Giant Space Guns (BFGs)

> I still think a massive gun in the Andes would be a lot cheaper in the long run.

We studied that about 20 years ago at Boeing. The muzzle velocity is set by the speed of sound of the working gas, so the best option is hot hydrogen, and the max temp is set by parts of the gun melting. Since the max velocity is limited, the g-forces are set by the length of the barrel. A 2 km barrel on the side of Mt. Cayembe in Ecuador (right on the Equator) requires 400-1000 g's. That's not for humans or delicate spacecraft parts. It's fine for bulk materials like propellants.

If you extend the barrel off the mountain onto the nearby plains, you can get 20 km, and if you limit it to 6 g's so people and delicate hardware can survive, you emerge at Mach 5. That's a good start to getting to orbit, but you still need a rocket to finish the job. Even a high-g gun needs a small rocket stage to get to orbit, but way less than a conventional rocket.

One drawback is a big barrel on a mountain can't be pointed - it goes only one place. On the plus side, since it doesn't have to fly, it can be made of heavy duty industrial parts, and last a long time. For such a gun to make economic sense, you need a lot of traffic to the particular orbit the gun is pointed at. Steerable guns can be built in the ocean, but they need to fly through twice as much atmosphere, and are less efficient. You can also build multiple guns pointed to different orbits, but again, you need enough traffic for each gun to pay back the construction cost.

SpaceX starts nine-day countdown to first flight of the new Falcon

Dani Eder

Re: Focus!

It's the other way around. Robert Downey Jr. based his characterization of Tony Stark on Musk, right down to his halting speech patterns. The cameo Musk did in Ironman 2 was effectively him talking to himself.

Dani Eder

Re: Matchless 500 single? Skylon, Musk

Not very far. SpaceX gets revenue now for Falcon launches, which pays for further upgrades and development. Skylon brings in no money until the complicated engines and airframe are completed. Since those two parts have to be integrated, you can't start flying with an early version and upgrade over time.

US govt just can't hire enough cyber-Sherlocks

Dani Eder

Things haven't changed much

When I first came out of college, 35 years ago, government engineering jobs paid 25% less than industry. Guess where I went to work? I ended up with Boeing as a government contractor.

Sun of a b... Solar winds blamed for ripping away Mars' atmosphere

Dani Eder

Subtitle error

The article subtitle says "Terraforming Red Planet going to be much harder than thought". This is erroneous, since the background loss rate (100 g/s) divided into the mass of the atmosphere gives a 7 billion year life. When combined with solar storms, we still get a "half life" of 500 million years. Half-life is the appropriate measure, because the loss rate is proportional to how much atmosphere there is to lose. If we can terraform the atmosphere in the first place, we can certainly compensate for leakage of 1% every ten million years.

The idea of terraforming the whole planet, though, is not reasonable unless you have many millions of people living there. It is more sensible to terraform only the area under your habitat domes, where the people are. Since outside pressure of the Martian atmosphere is much lower than Earth-normal pressure, the dome is a "pressure vessel" in the engineering sense. It turns out the minimum load is when the weight of the dome is equal to the pressure inside. On Mars that is 25 tons per square meter. It doesn't matter what you use to weight the dome, glass or rock. But when you put that much matter overhead, it is effective radiation shielding, even better in fact than the 10 tons per square meter of our Earth's atmosphere.

As the population grows, you keep building more domes, until you dome over the entire planet. At that point you have solved both the radiation and atmosphere leakage problems.

The Steve Jobs of supercomputers: We remember Seymour Cray

Dani Eder

Bitcoin miner

These days, anything other than custom bitcoin mining hardware isn't worth the electricity it consumes.

The bitcoin network currently runs at 5.5 million Petaflops. That far outclasses the 361 Petaflops of the world's top 500 supercomputers *combined*. The reason the network is so fast, is these days it runs on custom chips that implement the hashing algorithm in hardware, and are massively parallel. The downside is these chips are useless for almost any other purpose. You can't reprogram them to do some other calculation, it is wired into the silicon.

The reason these custom chips were worth making is newly mined bitcoins are worth $315 million a year at the moment, more than enough to justify a custom chip.

FORKING BitcoinXT: Is it really a coup or just more crypto-FUD?

Dani Eder

Re: I guess that eventually...

Not every client needs to keep the complete transaction history. You can prune all addresses that now have zero balances (which is most of them) and are left with ~1 GB of transactions and addresses that are non-zero.

When the block chain gets too big for home computers, you can set up subscription servers at data centers, with lots of hard drives. This was always a planned-for evolution. As long as there are many of these servers, and they are independent of each other, you can ensure the integrity of the transaction history

My credit union, for example, has 73,000 members. They could easily host a 4U server with 36 x 4 TB hard drives. That allows for 3200 times growth over today's block chain size.

Shields up! Shields up! ASTRONAUTS flying to MARS will arrive BRAIN DAMAGED, boffins claim

Dani Eder

Shielding source

> The problem is getting all that water onto the spaceship in the first place. If you are launching from Earth - not a way in hell. It is not feasible. If it has been brought into Earth orbit from the Asteroid belt., than it is a completely different ball game.

The inner Solar System is filled with asteroids in random orbits. 12,500 have been found in the "near Earth" category alone, and there should be similar numbers between Earth and Mars. Some, the Chondrites, contain up to 20% water and hydrocarbons. The answer is then to send a tug to move some of that asteroid rock into a repeating Mars transfer orbit, and stuff it into a cylindrical shell of storage lockers. When you launch your crew mission, you meet up with this shell, and slide the habitat module inside, then travel protected by the shielding layer.

Since the asteroids are in random orbits and there are lots of them, you will always find ones that are already close to the orbit you want, and therefore don't have to move them very far. For a bonus, you can process some of the rock for supplies. Your tug can maintain the shielding's transfer orbit, since such orbits are not naturally stable. You can then use it on later missions.

Dani Eder

Re: Not really equivalent

The Earth's magnetic field deflects most of the external radiation from the Sun and cosmos, but it also traps a part of it in the Van Allen radiation belts. The magnetic field is tilted and offset from the geographic poles, so there is one region (the South Atlantic Anomaly) where the belts are lower than elsewhere. That's where astronauts in low orbit pick up most of their radiation dose.

Skylab was in a low inclination orbit, and the belts are aligned mostly east-west. The ISS is in a higher inclination orbit to accommodate launches from the various international partners. So it crosses the South Atlantic Anomaly more perpendicular, and thus spends less time in it. The ISS also has more equipment around the walls of the modules compared to Skylab, which provides some amount of shielding. So the exposure rate is considerably lower (about 2/3 lower, but I would have to check).

Black Beauty Martian meteorite IS a SPOT-ON match with Red Planet's DARK PLAINS: boffins

Dani Eder

Selection bias?

> “This is showing that if you went to Mars and picked up a chunk of crust, you’d expect it to be heavily beat up, battered, broken apart and put back together,”

The only way this Black Beauty meteorite could end up in the Moroccan desert is as a result of a giant asteroid impact on Mars - one big enough to fling objects at escape velocity. It should be pretty obvious that this particular rock will show signs of being beat up, but that does not mean the rest of Mars is that way.

A similar selection bias happens with Chondrite vs other meteorite types. There are a lot more Chondrites in space than are found on the ground. But chondrites by their nature are made of stony particles bound in an organic matrix (a sort of primordial asphalt/macadam). The organic bits tend to burn up as the meteor enters our atmosphere, leaving nothing to find afterwards.

Why so tax-shy, big tech firms? – Bank of England governor

Dani Eder

Fiduciary Duty

Shareholders *are* the company, in the sense of owning it. Thus they can't have any obligation to themselves. It is the corporate officers and directors who have a fiduciary duty to act in the best interests of the owners (the shareholders). Maximizing the value of the company is part of that duty, although over what time period is a matter of judgement.

Volunteering to pay more in taxes than is necessary would be considered not acting in the best interest of the shareholders.

NASA probe snaps increasingly detailed shots of MOIST DWARF goddess

Dani Eder

Re: only question is...

(1) It's a bit difficult to hollow out a body that likely has a subsurface ocean.

(2) The central pressure of Ceres is about 133 MPa (19,000 psi). That exceeds the strength of typical rock. So if you hollowed it out, it would collapse. In fact, the very definition of dwarf plant is based on being large enough to crush the interior and adopt a round shape. Smaller bodies are notably irregular.

(3) Google wouldn't want a high ping time from Evil HQ to everything they control. At most they would move it to low orbit, among its future constellation of laser death comsats.

Scientific consensus that 2014 was record hottest year? No

Dani Eder

Re: Nope

> In other words the warmists want to take away your money and your standard of living (for your own good, they would say)

Nope. When I insulate my home or get solar panels, I do it when it makes economic sense. Thus I keep my money and improve my standard of living - I can afford to keep the house warmer in the winter because my heating costs are lower.

As a tree farmer, I could absorb 100 tons/year of CO2, make money at it in the long run, improve the utility (mature forest looks nicer and is easier to walk through than when full of young saplings) and improve the habitat. Once the forest is mature, you can store carbon in the form of durable wood products (houses and furniture) and biochar (a long lasting soil-improvement). So long as you limit harvesting to the rate the mature trees regenerate, you can continue to remove carbon for a very long time.

My point here is if you are smart, you can enjoy benefits *and* help reduce the risk of climate problems, at no net cost.

Dani Eder

Economists only measure money

> But economists would have kittens.

Economists only measure when money changes hands. They don't count work or production in the home. Thus housekeeping, home improvement, gardens, or solar panels for home consumption don't show up in the GDP statistics. As robots and home automation get better, we would expect more to be done locally. As solar panels and electric cars get more common, and are used for self-charging, there is no money changing hands, but it displaces fuel sales at the pump.

So, as you say, unless economists update how they measure things, they will have an inaccurate view of what is really happening in the world.

Dani Eder

Re: Thermometers

For the US at least, NOAA accuracy standards are +- 1F (0.55C) with 95% confidence, which converts to a 1-sigma error of about 0.25 to 0.3C

Source: page 7 of http://www.nws.noaa.gov/directives/sym/pd01013002curr.pdf

However, it is a well known fact of physical measurements that if you average many independent readings, the error band will get smaller by the square root of the number of measurements. Thus for a year's worth, the average should be 19 times better, or 0.013 to 0.016C. Of course, that assumes the measurement conditions did not change during the year.

If the worldwide accuracy is +/- 0.05C, and you want to find out if there is a significant trend, then the proper thing to do is take a 25 year running average. That will average out the significant annual weather variations, and bring the measurement error down to 0.01C, which is lower than the expected rate of increase (0.02 to 0.06C/year). But climate skeptics don't want to do that. They want to cherry-pick an especially hot El-Nino year (1998 or so) as the base point to determine a trend.

As far as "hottest year on record", looking at air temperature alone is idiotic. The oceans have 5000 times the thermal mass of the atmosphere, and melting ice absorbs as much energy as raising liquid water 80C. The world's ice caps and permafrost only melt a little each year percentage-wise, but they account for a large amount of thermal energy. We also haven't had a large number of thermometers in the oceans until very recently, so it is difficult to see a trend. Satellites can measure ocean surface temperature pretty well. But the bulk of the oceans is below the surface, naturally.

Gorilla Glass maker gobbles Samsung's fibre optic biz

Dani Eder

Re: Best Known?

Corningware is still manufactured by Eurokera, which is partly owned by Corning, Inc. The marketing is done by a third party, however. Eurokera also makes glass cooktop surfaces, another product which is designed for thermal shock.

No need to worry: US blows $174m on new Cray to simulate nukes

Dani Eder

Useless for Bitcoin Mining

This new supercomputer will have 1/800,000 the speed of the bitcoin mining community, and is therefore useless for verifying the financial transactions on that network. The reasons it is so outclassed are (1) bitcoin mining has a financial reward, and people will do anything for money, and (2) they use custom chips optimized for the task. The Cray supercomputer is more general purpose, able to do any kind of scientific calculation.

The point of my comment is not bragging rights, but to point out how much you can gain from custom chips. It might be worth designing custom chips just for nuclear simulations, and dramatically lower the cost of the computer. The first custom bitcoin chips were designed by one person and manufactured for far less than $174 million.

That AMAZING Windows comeback: Wow – 0.5% growth in 2015

Dani Eder

Re: There's not much wrong with windows

> The reason people aren't buying laptops any more is simply because there is no compelling reason to change them, not because they're using them less.

I have two desktops and a laptop that are 5,8, and 10 years old. I'm seriously thinking about replacing the 10 year old one. The pace of core hardware improvement (i.e. the CPU) is much slower than it used to be, and the market is saturated. I'm not about to buy a 4th computer, and every office worker who needs a computer for work probably already has one. So it is now a replacement market when either gradual improvements or hardware failure demand it.

Annual sales data ignores the installed base. If you are selling 300 million new PCs a year, but only disposing of 150 million broken or obsolete units, the installed base is still growing, even if annual sales are down from what they were a few years ago.

Dani Eder

Design times

> In the 1960s, Boeing designed the 747 in 16 months. a tiny fraction of what it took to design any other 7x7 since then. But then they didn't get slowed down by productivity tools.

I used to work for Boeing. Productivity tools have nothing to do with how long it takes to design an airplane, since they are designed on CAD/CAM software like CATIA. Instead, what has happened is the complexity of the airplane and the factory has drastically increased. Aluminum is a uniform material, while the graphite composites have directional weaves that have to be specified. A 1960's airplane effectively had no digital electronics. Today's planes are stuffed full of computers everywhere.

Another factor in recent decades is the demand of other countries for a piece of the production, in return for their national airlines placing orders. Spreading the work across different countries with different languages and time zones complicates and slows down the design and production coordination.

Elon Musk: Just watch me – I'll put HUMAN BOOTS on Mars by 2026

Dani Eder

Re: That about wraps it up for SpaceX

> Nobody actually knows if there really is any significant money in private space ventures

On the contrary, space industry is $300 billion a year worldwide, and about 2/3 of that is commercial. Satellites deliver TV, music, internet, navigation, and other services. Satellites are expensive and are discarded when they break or run out of fuel, so the next growth area will likely be refueling and maintenance. Robotics and remote control have gotten to where that is feasible, and ion thrusters can get you there efficiently.

Dani Eder

Other Difficult Stuff

> once they have the big, difficult-to-do stuff (like getting off this planet at a low cost while taking as much mass as possible with you)

Launch costs are important, but not the only important thing needed to colonize the Solar System. Even with cheap rockets you can't afford to haul an entire city's worth of habitats and equipment with you. Thus you need to mine and produce most of what you need locally. Ideally what you want to send is a core set of starter machines, and use them to build out the rest of what you need.

The technology for that is much less developed than rocketry, which is why I have started working on it now: http://en.wikibooks.org/wiki/Seed_Factories By the time it's needed in a decade or two we hope to be ready.

PARTY TIME! MIT slips $100 to each student ... in Bitcoin

Dani Eder

> Someone will 'invent' a kiosk teller machine that dispenses U.S. Dollars and "Bitcoin,"

There are already two such bitcoin ATMs in Boston, one at the underground rail South Station, and the other at Harvard Univeristy. Both are about 2 km (1.5 miles) from the MIT campus.

US Senator lobbies feds to BAN BITCOIN

Dani Eder

Re: Isn't that factually incorrect as well?

Transactions are relayed across the network in a matter of seconds. Each node in the network checks the transaction for validity, including if the sender had enough funds to spend. They do this by looking at their own copy of the Block Chain to see what the balance was in the sender's account(s).

For buying a beer, this level of verification is sufficient - the bartender doesn't have to wait. Bitcoin "miners" take incoming transactions, like any other node, but also attempt to find special hashes (checksums) for a set of transactions. That's called a block. The block also includes the previous block's hash as data. If anyone tries to alter the contents of a block, it no longer will match it's hash. If more blocks have been produced since, you would not only have to find a matching hash for your altered block, but every one after it, because each hash is part of the data for the next block.

By design, the special hashes are so hard to find, that the entire network of miners takes 10 minutes on average to find one. Since they are all busy making new blocks to claim the block reward (worth $15,000 per block at the moment), there isn't enough computation power to generate falsified block data.

So, you can see transactions validated to a reasonable level arrive in seconds. But over time the accumulation of blocks makes the record of that transaction effectively immutable. The bigger and more important the transaction, the longer you might want to wait for more blocks (confirmations) to arrive. Six blocks (one hour) is considered good enough to buy a house with. Conversely, if you are selling a house, you might want to wait for 6 confirmations on the buyer's funds, to make sure his money is good before the purchase.

> I also thought the block chain of a given coin can be analysed to discover the history of every wallet it's ever been in.

The Block Chain is a public record of every bitcoin transaction, ever, from the creation of a given coin in a particular block, and where it's gone afterwards. But the transaction records only the amounts, and the addresses it come from and goes to. A wallet can hold multiple addresses, and most of them generate new addresses for new transactions. Wallets are just files that hold the private keys tied to an address, which allows you to sign transactions for the balance held in that address. One file can hold a lot of keys, they are only 32 bytes long each.

Which wallet controls a given address, and who owns the wallet and where the file is located is not part of the transaction, thus it cannot be deduced from the Block Chain itself. It has to be found from other data elsewhere. If I spend bitcoins with an online merchant, and give them a delivery address and name, then they know who I am. But since bitcoin addresses are not typically reused, them having my sending address is not useful, it's been emptied. I'll automatically generate a new one for the next transaction. That's much more secure than with bank credit cards, where the number stays fixed for the life of the card.

Dani Eder

Re: "the currency helps facilitate criminal activity"

The Code of Hammurabi has laws against financial crimes. It's probably safe to say criminals have used money as long as there has been money. New kinds of money means new kinds of financial crimes, but it's not as though bitcoin is the first place for this to happen.

Accused fraudster Charles Shrem quits Bitcoin Foundation board

Dani Eder

Equal Justice? Nope

Big banks launder billions of dollars a year. Do any of them get indicted? Nope, their CEO's get raises.

Altcoins will DESTROY the IT industry and spawn an infosec NIGHTMARE

Dani Eder

Re: Come and get them

I hope you realize that floriculture (growing of flowers for money), including tulips, is a $100 billion business worldwide. Just because there was a bubble in tulips once, and US housing more recently, does not mean the underlying asset is worthless. People just get overexcited sometimes and drive the price above it's fundamentals.

What are the fundamentals of a distributed payment network? In the case of bitcoin, it can move money internationally faster and cheaper than the alternatives (Western Union, PayPal, bank wires). Those features create demand to use the network. Since the bitcoin currency unit is necessary to move balances between users, that demand also gives the units a value. But you cannot separate the units from the network that moves them. Without the network they are immobile and useless.

People are led astray by the "coin" part of bitcoin's name. We are familiar with coins as something in your pocket with an independent existence. Bitcoins are not like that. They are inseparable from the network, because without it, you cannot make and verify payments.

Bank of America: Bitcoin could become THE currency of e-commerce

Dani Eder

Re: Flawed assumptions, Dani Eder's proposed solutions

1) And that 50% will agree to raise the cap, because then they can earn more in transaction fees. It's in their economic self-interest to handle more transactions. However bigger blocks can cause other problems, which is why the simple solution has not been immediately adopted by the developers.

2) It doesn't have to be evil bastard banks, I just used them as an example. You can set up a local non-profit association for the purpose of saving transaction fees, or release "transaction pooling software" as open source.

3) We already deal with this even with just Bitcoin across different currency markets, not to mention other altcoins:



Dani Eder

Re: Flawed assumptions

People have been aware of the transaction rate limit, and are working on solutions. The simplest is just to raise the cap on block size, which is 1 MB/block currently. Another approach is to move the bulk of transactions "off-chain". For example, Bank of America could handle transactions among their customers internally, and only send a bulk transaction on the main block chain to Citibank (with a separate note detailing how the funds should be split up).

Finally, people could spin up an exact duplicate of bitcoin on a second block chain that runs in parallel, with some means of transferring funds between them. Repeat as necessary. This sort of exists already with the three dozen or so alternate cryptocurrencies, except those are all different, rather than exact copies.

Stewardess first to book $250k Virgin Galactic 'space trip' with BITCOINS

Dani Eder

Bitcoin loans

Loans today have a built in estimate of inflation, plus a "real return" that the lender wants above inflation. If you make a loan in a deflating currency like bitcoin, the inflation adjustment is simply a negative rather than a positive number applied to the "real return". Mathematically there is no problem doing this, even if it seems odd to most people who are not used to finance math.

In reality, nobody in their right mind would make a loan denominated in bitcoins today, it is too new and unstable in value. Barrels of oil or gold bars are rock steady in value in comparison. Assuming the acceptance of bitcoins grows, and it is distributed in more hands, it should settle down, but bitcoin was not designed as a stable store of value. It was designed as an efficient way to transmit value across a network, which it does admirably.

Bitcoin blitzkreig as Germans prepare to tax virtual currency

Dani Eder

Re: Since they are going to be trying to tax mostly drug income...

> I would hazard a guess that the vast majority of bitcoin activity is on sites such as Silk Road.

Actually, Forbes magazine's estimate of the Silk Road's revenue places it at under 1% of bitcoin transactions. There are over 7500 merchants using just one bitcoin processor, BitPay, to handle payments in bitcoin and converting it automatically to deposits in local currency. The Silk Road is notorious, because the media could not resist it as a story, but it is actually a small part of the bitcoin economy these days.

Spam and the Byzantine Empire: How Bitcoin tech REALLY works

Dani Eder

Re: What the author of the article did not explain

You can pay for bread using this: http://app.gyft.com/me/cards/purchase/ (CVS and K-Mart at least carry bread).

The reason for *merchants* to take bitcoin is they can save about 5% of the amount of a sale vs bank cards. That comes from reduced fraud and bank fees. In turn, merchants can pass some of that savings on to you, the same way some merchants offer a cash discount.

Other reasons to use Bitcoin as an individual are the ability to work anywhere in the world for anyone in the world, increasing job opportunities. If you want to send money overseas, the fees are vastly lower. If you want to shop online and live in countries that credit cards and paypal do not service (there are lots of them), there is no other way to buy the items. Therefore you would be willing to take bitcoins so that you can spend them on things.

Perhaps these reasons will not apply to you, which is fine. Not everyone is the same, and there is room for bitcoin to service the people for whom it does work, alongside more traditional payment networks.

Dani Eder

Re: Good explanation of the technical side

People exchange about US $30 million a day of real goods and services for bitcoin. As the article explains, bitcoin is just the ledger for tracking exchanges between people. The network of real items that people exchange back and forth is what gives a balance on the ledger value.

Dani Eder

Re: Transaction fees

Transaction fees, which are what will power bitcoin mining after the initial distribution of coins are done, amount to 0.025% of the transaction value they are based on. That is not an excessive overhead for running a financial network. Miners, therefore, will not use more computing power and electricity than that 0.025%, because they would be losing money on the task.

As far as total power use, if everyone used ASIC type mining rigs, the entire bitcoin network would consume 820 kW. You can compare that to the 19 MW Apple uses for their North Carolina data center.

Space elevators, vacuum chutes: What next for big rocket tech?

Dani Eder

Re: Feasible Space Elevators

I haven't ignored it. For a Rotovator design, you hook on and ride half a rotation and then let go. The forces are purely radial in that case. If you are climbing from the tip of rotation to the center, you do see a Coriolis effect, but let's look at the numbers.

Assume you have a maglev-type track that lifts a payload from the tip to center in 3 hours (200 km/s for a ~600 km radius), and the tip velocity is 2400 m/s. Therefore you much transfer 0.22 m/s angular velocity to the structure. The radial tension in the structure is 9.8 m/s at the tip, so you produce 2.2% deflection from purely radial while climbing. This is a manageable deflection of the cable structure.

Dani Eder

Re: Feasible Space Elevators

You clearly don't understand orbital mechanics. Of course grabbing a sub-orbital cargo and accelerating it to higher orbit will lower the Rotovator orbit. That I why I mentioned on-board propulsion to make up the kinetic energy lost.

That allows you to substitute low efficiency rocket (on an unassisted rocket) for high efficiency electric thrusters (on the Rotovator), saving you 90% of the propellant consumption, which turns into more payload.

I spent a career in Boeing's space systems division, and am writing a book on the subject ( http://en.wikibooks.org/wiki/Space_Transport_and_Engineering_Methods ) so please credit me with having a clue what I am talking about.

Dani Eder

Re: Zero velocity?

Actually, Cayambe in Ecuador ( http://en.wikipedia.org/wiki/Cayambe_%28volcano%29 ) is a better choice. Its the highest point on the Equator and has decent slopes for ground accelerators.

Dani Eder

Feasible Space Elevators

Trying to span the depth of the Earth's gravity well with a single structure is terribly non-optimal from an engineering standpoint for a number of reasons. Smaller elevators, however, are quite feasible with off the shelf carbon fiber.

Imagine a rotating cable with a tip velocity of 2400 m/s, and a comfortable 1 gravity at the tip. The radius then works out to 587 km. You don't want the tip to enter the atmosphere, so you set the orbit of the center to 750 km, and the lowest point is then 163 km. The center then orbits at 7.48 km/s, and the tip is moving 2.4 km/s less or 5.08 km/s. Subract the Earth's rotation and you have a velocity of 4.61 km/s relative to the ground.

Your launch vehicle now has a much less challenging job than getting all the way to orbit by itself. It merely needs to reach a landing platform at the tip of the cable. To return to Earth, it has much less velocity to dissipate, so the re-entry heating is much less. Cargo heading to higher orbit merely rides for half a rotation, then lets go. It now is moving at 2.4 km/s above orbit velocity, which puts you in a high transfer orbit.

The load on the cable varies linearly from center to tips, therefore is equal to a cable under 1 g half the length, or 293 km. Good carbon fiber has a breaking length at 1 gravity of 360 km. We want a decent margin of safety, so only load the cable to 40% of ultimate strength. This requires tapering the cable from center to tip, as each point has to support the payload + cable outside that radius, but the taper ratio is not severe, about 7:1 in area.

Because this design is 40 times shorter, it is much less exposed to meteor and debris damage, but they still are a risk. Therefore you build the cable out of something like 21 strands, of which 7 are spares, and cross-connect them every 5 km. So when the inevitable impact happens, you only have to replace the one 5 km segment, which is 0.02% of the total structure. The "single cable" illustrations like the one in this article are just terribly unrealistic from a safety standpoint.

This type of rotating space elevator is called a Rotovator, and can start being useful while under construction, so you don't have to build it all at once. As the length increases, and tip velocity goes up, the launch vehicle needs less velocity, and can therefore carry more payload. If some of the payload is more cable for the Rotovator, the increased cargo on later flights "pays back" the payload spent on launching the cable. This payback time in cargo mass can be relatively short.

You can build a second Rotovator in high orbit, which captures payload sent up by the first one in low orbit, and forwards them to interplanetary trajectories. Since kinetic energy is not free, you need onboard electric thrusters to maintain the Rotovator orbits, but those have ten times higher efficiency than conventional rockets, so you still come out very much ahead on net cargo.

Bitcoin prices spike on Euro woes

Dani Eder

Re: In troubled times...

> I'm not sure I would rank bitcoins as safer than euro stored in a bank backed by a deposit guarantee, the ecb

Cyprus *had* a deposit guarantee, they just threatened to bypass it by taxing deposits. And it was the ECB who was encouraging this theft of depositor funds. The sudden interest in bitcoin is from other people in Europe wondering which other banks might decide to renege on their guarantees.

I agree that shifting your life savings into bitcoin is a bad idea, it is too new and unstable for that. But being inherently transnational, it is a good way to move your money to a safe haven outside the control of the ECB and euro bankers. The risk in using it for funds transfer is much lower, since you would hold them for only a short period of time.

'Gaia' Lovelock: Wind turbines 'may become like Easter Island statues'

Dani Eder

Re: Green Concrete

Concrete can be green if you use a solar furnace to make the cement for it. I plan to prototype such a furnace in the near future.

Background: The reason for concrete being considered not green is the large amount of energy needed to calcine (burn) limestone and shale to make the cement. This energy usually comes from fossil fuels in a cement kiln. The rocks you are heating don't care how they get hot, so a solar furnace works just as well, so long as you can get it hot enough.

HP maintains seat atop wheezing, spavined PC market

Dani Eder

360M is still a lot of PC's

90 million PCs per quarter works out to 360 million per year. I already have two of them, so I don't need to buy another until my second one gets so old it's useless, and the new models are enough better than my quad core i7 to be worth an upgrade.

The point is, they are still selling a lot of PCs, and the market is getting saturated. Unless the hardware makes a great leap forward, existing models are good enough for many people.

Three little words stall UN's 'bid for INTERNET DOMINATION'

Dani Eder
Thumb Up

Re: Google > ITU

What are you talking about? I tried "Naked Boobies" in Google image search, and got a page full of topless women. Works just fine as far as I can tell.

Dani Eder

Google > ITU

This is why I would rather have Google as my Internet overlord than the ITU. They at least understand how the darned thing works.

Governments are a local monopoly on force. Since humans are self-interested, they will always try to leverage that monopoly into total control. Therefore you have to provide strong limits on government power, such as constitutional guarantees of certain rights and limits on their ability to meddle in things they should not.

If you want to make certain actions illegal (possession of child porn is the poster child (pun intended) for such actions), make the possession illegal. Don't go breaking use of networks, video cameras, studio rentals, and cash because they *might* be used for that purpose. They have other uses that are perfectly legitimate, so you end up punishing the bystanders and not just the criminals.

Dani Eder
Thumb Down

Stick to technical standards

The ITU should stick to technical standards for the same reason we set standard voltages on electrical outlets or standard symbols on highway signs. We didn't vote these guys the powers to decide anything political, so they should keep their mitts out of issues like security, public vs private, and what constitutes content and speech.


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