I can see that they are for sale, at an extraordinary price, on the web. But that doesn't mean much: it may just be that gullible buyers exist.

The real question is do they really work, and if so how? I'm not aware of any technology that is capable of converting infra-red to visible light except with a significant input of power, which is obviously not available in the case of contact lenses.

Whatever you do in the US, don't do the metrication half-way like we've done in the UK. We buy gasoline and milk in litres, but beer in pints. If you go to a DIY store you can find some sheets of plywood etc with dimensions stated: 6 feet by 3 feet by 5 mm. People tend to measure their height in feet and inches but their weight in kilograms - that makes the BMI figure quite interesting. We've taken over a century to do our metric conversion, and it's still under way, unfortunately.

As someone who has been forced to use the chip-and-pin system for some years (because I live in the UK) I can tell you that it's not that much more secure. The intrepid researchers in the Computer Science Dept at Cambridge have shown that there are many ways in which it can be compromised. The reason our banks are so keen on chip-and-pin is that if your card is misused you, the customer, have to foot the bill. When we had to sign credit card slips and someone forged your signature it was the bank (or other credit card issuer) which was liable. Shops also like it because the banks charge them a tiny bit less commission. What you in the USA should get rid of is your ridiculous system of requiring input of a zip code at gasoline stations. I can never use my non-US credit card to get gasoline in the US because I don't have a US zip code, and the machines appear to have no fall-back system as an alternative. I can't believe that the system gives you any significant amount of extra security.

Absolutely right. But you didn't bother to post the only international number, which is 112. This works throughout the EU and in quite a number of other countries besides from land-lines, and on all mobile phones using the GSM system (which is most of them, maybe nearly all). This is the number to teach children, and to use in articles about emergency calls.

One very useful thing that the new digital text service doesn't have is the accurate time. Old analogue teletext had a display of hours minutes and seconds. New one has only hours and minutes, and because of decoding delays etc. even the minutes don't change right on the 0 seconds point. I have to find another way to check my watch.

Maybe it's going to be a slow process, but there have quite a number of news stories recently saying that both Visa and Mastercard are going to introduce them quite soon, e.g. http://www.pcmag.com/article2/0,2817,2399772,00.asp For those of us with credit cards issued in other parts of the world, where we have put up with the infernal system for some time, at least it might mean the end of being faced with gas stations insisting that we enter our Zip Code (which we don't have) before we can get gas.

I would have thought that the change to chip-and-pin cards in the US would have forced most places to invest in new POS infrastructure. That's certainly what has been going on in Europe over the last few years. Restaurants, especially, have had to invest in lots of new wireless POS terminals so they can take their machine to your card at the table. Maybe IBM doesn't think there's much money in all this new hardware, but somebody obviously does.

The only reason I have a current Motorola phone is because it's GSM 4-band (which one needs to use it in North America and the rest of the world), and because it has a clamshell design, which means the buttons don't get pressed by accident when it's in my pocket or a briefcase. Losing the latter, is crazy, as it was the only really good feature, and one which you can't get from otherwise decent phone manufacturers like Nokia. I won't buy a smartphone until they come out with one having a design which protects the display and the buttons when it's in my pocket along with keys, loose change, pocket knife, and whatever.

Susan Greenfield has a history of making these claims, without a scrap of evidence to back them up. For a more sceptical treatment of the subject, see Ben Goldacre's Bad Science column of a couple of weeks ago: http://www.guardian.co.uk/commentisfree/2011/oct/21/bad-science-publishing-claims

That is really annoying for those who don' t live in the USA so have no zip code. It means two extra trips to the booth to get your credit card read and approved, and then debited with the actual amount of gas used. Almost all other countries use a PIN number (typically 4 digits) to approve credit card purchases done by machine but machines in the USA don't seem to be able to read them. I can't wait for the USA to catch up with the rest of the world.

But I suppose one can't expect any more of the only part of the world not to use International Standard road signs, A4 paper, 00 as the international dialling prefix, 230/240 volt mains, and metric units.

Because of the toolbar at the top, page down scrolls too far (using latest Mozilla) so I keep on having to press page down then the arrow to go up a line or two that has been missed.

The serious side-effect is that it makes it extremely difficult, if not impossible, for visitors buy a local SIM card for their mobile phone in order to avoid the rip-off charges that nearly all mobile phone companies charge for roaming. I guess governments are in league with the mobile phone companies in this respect.

When I visited Australia and bought a local SIM card it took me ages on the phone to register, since I didn't have whatever the Australian equivalent was of an SSN number, and the whole process cost me a lot of time and money, making the SIM-card purchase only marginally worth-while.

Fortunately the UK doesn't (at present) require SIM card registration, so visitors to here shouldn't have that particular problem.