To get a passport, a driver's license or a social security number, one needs a valid birth certificate. Suppose, for one reason or another you want a second identity. This is illegal and I'm not recommending anyone try it, I'm just interested in thinking about vulnerabilities in systems. Since the government can cross-check with official databases, just forging the piece of paper probably isn't going to work. A method that often seems to be used is obtaining the birth certificate of someone who was born around the same time as you but who died young (and, if possible, in a different state). This "paper chase" method has its disadvantages.

What you really need is an identity that has already been created and maintained, but not used by anyone else - a farmed identity. I'm sure there is a black market for farmed identities, but the question is - how do those identities get created in the first place? That's where the babies come in. If you are a mother with a brand new baby, what's to stop you from going to a doctor and saying "I gave birth to a baby in my house, without even knowing I was pregnant"? (Such things do occasionally happen). The doctor will issue a birth certificate (in addition to the one you already have) and then you have a second identity you can farm for your child (or sell on the black market, if you are so inclined). While most mothers of newborn children probably wouldn't think to do this, I'm sure there are some who do.

Even biometric identity databases can't completely solve this problem unless, whenever a new birth certificate is applied for, the child's biometric information is compared to all the other entries in the database. I'm not sure if that is likely to be practical (given the imperfect nature of biometric data).

One problem with this method is that the mother is now on record as having two different children within a very short space of time, neither of which are recorded as being a twin. This could raise red flags. The answer is for the mother to use a false identity when applying for the second birth certificate. I don't think it would be practical to only give a child a birth certificate after a strong identity check on the mother.

Strongly identifying everyone is a really difficult problem. Should it even be attempted at all? If you don't even try verify everyone's identity, there are certain things you can't do. You can't ban someone from driving, since they could just get a new driver's license under a different name. So if someone is a danger to others on the road, you have to punish them the same way as other crimes - by putting them in prison.

You can't prevent someone from voting more than once by using electoral rolls, so you have to use electoral staining (though I'm not sure if that's perfectly reliable, given the availability of solvents).

You can't give someone large amounts of credit without collateral, since they might just disappear and assume a new identity. I don't think that's likely to be a big problem in practice, since good credit takes time and effort to obtain.

You also can't keep people in (or out) of your country, since they can always obtain a new identity with a clean passport. But national borders tend to be rather porous anyway.

This leads one to wonder whether a fourth size of brick would be possible, with a size half that of normal Lego bricks. It would not be directly compatible with Duplo or Quattro, but would be compatible with Lego bricks in just the same way that Lego bricks are compatible with Duplo bricks.

This is not always possible, since the "bumps" in Duplo and Quattro bricks have indentations in them which are necessary for compatibility. Most Lego bricks don't have these. But some (particularly Technic Lego) do. This leads me to wonder if the Lego company at one point planned to make such half-size bricks. I'm guessing the reason they didn't was that the pieces would be too fiddly for most fingers, too easily lost/swallowed and too difficult to manufacture with the required accuracy (the edges might also have to be dangerously sharp in order to join properly).

The Lego company did actually make a smaller version of Lego called Modulex but the bricks are 5/8 size rather than half size and are therefore not compatible.

We'll start the same way, by hashing the date and that date's DOW opening to get a set of 128 random bits .

Given any area A we want to find a function (which we'll call ) mapping a set of bits onto a point , . We would also like to have the property that if is a subset of containing and if then . So if the New York State meetup happened to be in New York City, all the people who were just going to the New York City meetup would be there too. Another desirable property would be if the points were evenly spread throughout .

Here is an algorithm that I think fulfills both properties.

First, use to pick a random point on the globe, taking 64-bit random floating point fractions and in from in the usual way and then transforming them into longitude and latitude as:


Where takes the fractional part, leaving a number between 0 and 1 (one could also use XOR instead of add and ) and is the smallest integer that causes the resulting coordinates to end up inside .

and are functions that find points that are furthest away from any tried so far. They have binary expansions as follows:

N  a(N)  b(N)  c(N)     d(N)
0  0.000 0.000 0.000000 0.000000
1  0.100 0.100 0.110000 0.100000
2  0.100 0.000 0.010000 0.010000
3  0.000 0.100 0.100000 0.110000
4  0.010 0.010 0.001100 0.001000
5  0.110 0.110 0.111100 0.101000
6  0.110 0.010 0.011100 0.011000
7  0.010 0.110 0.101100 0.111000
8  0.010 0.000 0.000100 0.000100
9  0.110 0.100 0.110100 0.100100
10 0.110 0.000 0.010100 0.010100
11 0.010 0.100 0.100100 0.110100
12 0.000 0.010 0.001000 0.001100
13 0.100 0.110 0.111000 0.101100
14 0.100 0.010 0.011000 0.011100
15 0.000 0.110 0.101000 0.111100
16 0.001 0.001 0.000011 0.000010

And so on, to as many binary places as you need. If you interleave the bits of and you get , which looks like but with each even bit XORed with the bit to its left. is the binary expansion of the integers but with the bits in the reverse order (and flipped to the other side of the binary point).

The sequences and together are related to the Bayer matrix which describe a 2D ordered dither. If you want 65 shades of grey but only have a grid of 8x8 pixels, each of which can only be black or white, the most regular patterns with n black bits are described by those that have and black if and white otherwise.

Some of it goes to administrative overhead (it costs a lot of money to pay the people at your insurance company who are looking for excuses to deny you coverage). But a larger fraction goes towards the profits of the insurance companies. People invest in these companies (often as part of a 401k or other retirement plan) and get back a profit (at the expense of those who pay insurance premiums and consume healthcare).

But not all of a company's profits go immediately back to its investors - any reasonable company will spend some portion of their profits on research into ways to make even more money in the future. In terms of medical insurance companies, this generally means medical research - research into new techniques, medicines and gadgets that improve the state of the art and make us all healthier in the long run.

So if the US switches to public medicine, what happens to the state of medical research? If the massive profits go away, will the research money dry up too? I have heard concerns that socialized medicine will cause medical research to grind to a halt, leaving the entire world with 2009-level medical technology for the forseeable future. I don't think it will be quite that bad - there are other sources of medical research money than US insurance companies (the US government and other governments).

I hope that in the process of transforming the country to socialized medicine, the government continues the investment in medical research and changes its focus a bit. I have the impression that the direction of medical research is set at least somewhat by the treatments that will make the most money rather than the treatments that are medically best. Drug companies pursue research on drugs that they can patent, not new uses for existing drugs on which the patents have expired. Cures are pursued at the expense of prevention and finding causes. With a change in focus we can hopefully get more effective research for less money overall.

Once you have a medical condition that is likely to take many years to resolve and be extremely expensive, you're beholden to your insurance provider, since you are a liability for them. Should you be allowed to change insurance providers? Okay, most of us can't change providers anyway without spending a lot more (to avoid paying tax on our health premiums we're stuck with our employer-provided health plans) but suppose that problem was fixed?

Let's suppose the answer is no, you shouldn't be allowed to change (at least not without taking a cripplingly large increase in premiums turning it from insurance into a payment plan) - no business should be required to take on a customer that is guaranteed to lose them money. Then the "free market" aspect of health insurance is denied to those people who need it most - it's not a free market when you can't make a choice.

So let's suppose the answer is that you should - that insurers should not able to deny access to insurance based on pre-existing conditions (which really ought to include genetic predispositions). Then insurers have to factor in the costs of such patients to all their customers' premiums. That doesn't sound so bad at first glance but consider the consequences - suppose that insurance company A had low premiums but covered very little and insurance company B had high premiums and covered everything. Then all the healthy people get insurance from A and switch to B when they get sick. B's prices then rise to cover the cost of their coverage and what you essentially end up with is equivalent to not having insurance at all. This means that government has to regulate what coverage is provided as well as who it is provided to. All insurance companies will then provide that level of coverage but none will provide any more. We've gone from having no choice to having no real choice. Either way we fail to have a free market for healthcare.

Socialized medicine aka single-payer healthcare aka politically controlled medicine has problems too. In the UK, different districts decide which treatments they will offer, resulting in a "postcode lottery" for some treatments. Waiting lists of years are not unheard of for treatments that are not imminently life threatening, and doctors and nurses are overworked and underpaid compared to their counterparts in the US. However, the average Brit pays about half what the average US resident pays in healthcare costs and gets better coverage on average. There is also no worry about medically-induced bankruptcy, and no worries about one's insurance company refusing coverage (due to a "pre-existing condition") once a serious medical condition is found.

I disagree that single-payer healthcare gives patients an incentive to over-consume. It should not be the insurance company that gets to decide that - doctors should be ones to decide which treatments are medically necessary. And if some doctors are over-prescribing compared to other doctors in their geographical area or speciality, that is something that should be investigated.

Another criticism of single-payer healthcare is that providers have no incentive to compete on price - the government will have to pay whatever they ask for critical treatments. But there's nothing special about single-payer healthcare there - there's nothing stopping the government from acting the same way as insurance companies to do to keep a check on prices. In fact the government has more power than an insurance company there - the insurance company only has the power to drop an overcharging provider from their preferred providers list while the government has the ability to take away their medical license.

Yet another criticism is that if the government gets to decide what treatments are on offer, people don't have any choice. Well, most of us don't have any choice anyway under the insurance model but at least with the government you can vote them out if they aren't doing a good job with healthcare. Yes, socialized medicine means a government bureaucrat between the patient and the doctor, but better an elected bureaucrat than an insurance-company bureaucrat that one has no control over.

Now, call me overcautious but I wouldn't want to visit a place where it would be perfectly legal for anyone to kill me.

Perhaps the reason that we have not been visited by extra-terrestrials is simply that they think Earth would be a dangerous place for them.

Perhaps all we need to do to join the interstellar community is to pass a law affording the same rights that humans have to any aliens that might visit us.

However, even if Motl is right that still doesn't exuse us from having to invest in alternative energy sources, because fossil fuels are still running out. They've been getting more and more expensive for years and it's not because of the price of the dollar or the greed of oil companies - it's simply that we've already used up the oil that is cheap to extract, and what remains is more labour-intensive and therefore more expensive. This trend will continue until it becomes more cost-effective to use renewable energy sources.

It's in the interests of everyone (except the oil companies) that this happens sooner rather than later. The reason for this is that fossil fuel energy becomes more expensive the more money you spend on it (like diamonds, and for exactly the same reasons), and renewable energy gets cheaper the more money you spend on it (like computers, and for exactly the same reasons). Once all the money we're currently spending on oil goes into research into renewable energy sources rather than research into oil extraction methods, energy will get much cheaper very very quickly, and our transportation, heating and electricity costs will all go way down. Also, we will stop pouring so much money into the pockets of unpleasant middle-eastern regimes.

There are also environmental problems caused by fossil fuels that are not disputed at all, such as the damage caused by oil spills or the pollution caused by coal mining operations. However, we don't yet know what similar environmental problems will be caused by the renewable replacements (perhaps our solar panels will require elements for manufacturing that are also messy to mine, or poisonous chemicals). But given the amount of energy that will be generated by a solar panel (say) over its entire lifetime, it seems unlikely that the environmental problems of using renewable energy will be worse.

Prints tend to be slightly convex, so when placed on the scanner glass they tend to be in contact with it at only one point. This means that they will rotate about that point at the slightest provocation (like a gentle breeze in the room, or another photo being placed on the glass next to it, or removing one's finger from the photo once one finished placed it just so).

My scanner is just the right size to scan three photos at once, which is great apart from the fact that the sensor area of the scanner is slightly smaller than the glass, and the bottom of the third photo gets cut off. Fortunately it's only a small strip so I decided not to bother rescanning them all.

Then after scanning most of the photos I'll notice that there is a smudge or some dust on the glass which will of course appear in all the photos that I've scanned so far. Hopefully it won't be too noticable.

I am quite impressed at how well the photos came out given that the film in my old camera had been sitting there for the best part of 7 years (I guess it helped that it had been in dark cupboards and drawers for most of that time). I'm also quite impressed at the picture quality you can get from a disposable camera these days - comparable to my old compact 35mm. I guess that even with the rise of digital, 35mm technology has continued to improve. Digital is still so much better though.

I'll post the results of the scanning session here soon.