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It's no secret that France has long wanted the Meridian to pass through Paris, where other items that define weights and measure reside, so they can all be in one (*ahem* French *ahem*) place. Once we don't use Greenwich Mean Time the next step will be for France to re-name Paris as "Greenwich", ...

Heh. Apparently the French (and probably a lot of Brits, too) haven't heard that GMT hasn't been used for a quarter century now. The Greenwich Observatory got out of the time standard business back in 1986 (google it), when the official time standard was redefined in a way that wasn't dependent on any place or artifact, and renamed "UTC". Since then, "GMT" has been nothing more than a mispelling of "UTC", usually by someone who doesn't understand the difference.

Actually, if you visit the Greenwich Observatory, you'll find that they do have a nice museum exhibit of the history of their time standard, as well as a number of other good exhibits. It's well worth spending a day of your vacation there. Or visit their nice web site (www.nmm.ac.uk).

http://www.nmm.ac.uk/places/royal-observatory/meridian-line/

And some other things...

The UK has a high population density which has some forseeable consequences. Hotel rooms will be small, especially in central London. Trains and busses will be crowded in rush hour - if you don't have to be travelling between 8-9:30am or 4:30-6:30pm, then don't.

If you want oriental food, then Chinatown (Soho), just off Leicester Square and a 3-minute walk from Picadilly Circus, does exactly what it says on the tin.

Set aside 20 quid to have proper Afternoon Tea, 3pm onwards at the Terrace Bar in Harrods department store. Ask the besuited concierges for this specific bar (there are many). Ignore anyone who says Harrods is touristy; you are a tourist, so enjoy it and soak up the atmosphere. Service at Harrods is far better than at Fortnum & Mason, even if the prices match.

Do you like engineering? Break up a tube journey by having a look around St Pancras railway station, a marvel of Victorian ironwork itself, and where the rather swish Eurostar train starts its 200mph journey to Paris. Still engineering based, visit the Thames Barrier, a moving metal marvel which stops London from flooding.

Take the Docklands Light Railway monorail (included in your underground tube train ticket) to East India station and gawp at Telehouse Docklands. Note how British police do not carry pistols. Oh no. If they're going to carry a gun, they carry an assault rifle.

Visit the Grenwich Observatory, home of the GMT zero line and note with amusement that, although us British have given up most of our Empire, we still tell the rest of the world when to wake up and when to go to bed.

Walk past Buckingham Palace but make sure you also walk past St James Palace, only two blocks away, which is much older and has far more history.

Really, really, make sure you take a compact umbrella.

Is there a line in the Planetarium that says 'On this spot is the GMT line' or something, so if you take a photo on the West side of it, you could say," Look Honey I traveled back in time, but only a couple of seconds"

Kind of like the Four Corners I think it's called, that we have here in the US.

Yes there is. There's one on a public footpath that runs along the north perimiter of the observatory, which is free to access but cramped for photographs. If you pay to go into the observatory (strongly recommended!) there's a much more photogenic one in the courtyard. The obervatory is in Greenwich Park which has great views across the river and is a popular spot for family picnics on summer weekends. The Greenwich Maritime Museum is just a stone's throw away from there, and is good too if you're interested in naval history.

...but the Planetarium closed down a few years ago. It was turned into a "celebrity cinema" bit of Madame Tussauds, showing showbiz movies. Philistines.

However, the Greenwich Observatory has their own, new planetarium - it's brand new, and right by the Greenwich Meridian:

http://www.nmm.ac.uk/visit/planetarium-shows/

For a while, the US was seriously considering using the Washington Meridian as its "zero" reference for all US mapping. Similarly, at one point they were considering having a brand new unit of length, defined as the length of a pendulum that swung in exactly one second when dangled at sea level at latitude 45 degrees (which would have been similar to, but not quite the same as, the metre).

In the end they set aside the idea of having their own independent system, and went with what was already popular.

The reason why Greenwich Time was so popular wasn't especially political, it was just that Greenwich as a long-standing, reliable, well-funded, high-profile observatory that was practically on the Thames, really near to where all the international shipping came in to park to use the docks. An agreed time-base was critical for navigation, and Greenwich tried to provide one. In the 1830's they also instituted the Greenwich Time Ball", which was a visual signal that passing shipping could use to calibrate their clocks. Some places used cannons, but the speed of sound meant that if you were a way away, your timing would be off. Greenwich's light-signal was better, provided that you had your telescope pointed in the right direction at the right time.
Because it was near the docks, ships didn't have to worry about passing at exactly the right time - chances are, they'd be holed up there anyway. So "Greenwich Time" was a free, easy international timebase for shipping that let captains calculate longitude, lots of ship's captains carried Greenwich Time around with them to the rest of the world, and it was a natural reference for mapping.
It also didn't hurt when England standardised on Greenwich time nationally, so that in theory, you could get Greenwich Time at any English port.

By contrast, Washington Time wouldn't tie into to the same existing nautical map-base, there probably wasn't a huge amount of international shipping parked within view of the Washignton Monument, and since the US had trouble even insisting that US maps were drawn up with reference to the Washington Meridian and Washington time, they probably did the right thing by dropping the idea, and using the existing standard. It's easy to carry Greenwich Time around the whole UK and coastal Europe by boat, with very sensitive mechanical clocks, it wouldn't have been so easy to take Washington time to both US coasts via shipping. Things got easier with the railroads and telegraphs, but for US shippng to be redrawing all the existing sea-maps specifically for a new reference system that they didn't really need ... it probably wasn't a brilliant idea.

Lol, are you serious?

Sure

What is at the centre of a gaseous planet then?

We DO NOT KNOW.

Is it gas and liquid all the way done, lol.

Maybe.

The pressure might be high enough to force the liquids into a solid, OR the extremely high pressures generate enough heat to maintain a liquid or rocky core.

But we just don't know...

Due to the eccentricity of the earth's orbit, the actual position of the sun in the sky can be up to 15 minutes ahead or behind the expected position of the sun for the time. You need the calendar to get the 'Equation of Time' modifier, which is applied to the time as measured on the sundial.

Useful links to explain better:
Sundial primer: http://en.wikipedia.org/wiki/Sundial
Equation of Time: http://www.nmm.ac.uk/server/show/conWebDoc.351
A particularly accurate sundial, to

The whole story was created to deceive an unknown operational target; we can only guess who that might be - in this case perhaps Iranian or AQ agents. It would help probe their intel personnel and their capabilities - for instance, to study the manner in which the target reacts to the disinfo. Mr Akers knows exactly what is going on. He is clearly no fool (his background). It is hardly the first time somebody with credentials has been used, and perhaps paid, as a participant in disinfo ops.

That's not really true. This technology for instance could be easily adapted to propel icebergs. In addition to that, Ocean currents could also be utilized. Granted the iceberg won't move very fast, but what's the hurry? Even if you lose a third of it's mass along the way, that's still a hell of a lot of fresh water for the nations that need it, and a net decrease in the amount that the oceans will rise in the future. And this is assuming that you decide to latch on to massive icebergs. There's also the option of harvesting the ice in place and using large tankers to transport it. In fact, this is already done in northern parts of Canada in order to produce bottled water. We're just talking about a much larger scale.

"All it means is that the chunks of ice breaking off are bigger so survive longer, and that the ocean currents are in the right direction to bring them to New Zealand. If there were lots of them for a sustained period, it might cause local cooling in the area, but otherwise the local temperature isn't all that relevant."

Hmm, I guess the disclaimer didn't work, people do think this was caused by global warming (despite the fact that the phenomenon is common enough to have happened decades ago).

Yes, global warming can cause many different diverse effects in the world. However, that doesn't mean that every phenomenon we see in nature was caused by global warming.

"New Zealand's latitude is roughly the same as the South of France, Spain and into Morocco, to put it into perspective for people in the Northern Hemisphere (though Europe is in a warm current, so the equivalent latitude in East Coast US might be a better indicator of ocean temperature - probably centered somewhere around Washington DC I think)."

More like Maine. But you need to check your current maps again, the East coast is also in a warm current. So a better comparision would end up being off the coast of Washington State, not DC. And if there was a source of ice as big as Antarctica in the North Pacific, they may well see icebergs near their coast every couple of decades.

Why does a Hydrogen Bomb produce far more energy in the fusion phase than is put in during the fission phase? My only guess is that the extra energy is coming from the energy released by the nuclear bonds during the forceful disintegration of the atom. Any physics majors care to chime in?

Ever wonder why all those protons like to sit happily in the nucleus together even though they're all positively charged? Well it turns out that at REALLY small scales there is a force called (aptly) "the strong nuclear force" which is about a million times as strong as electromagnetism.

The amount of energy it takes to liberate a single nucleon from a nucleus is called the "binding energy per nucleon". . For different elements this value is different. The reason fusion and fission can both release energy is due to change in this binding energy per nucleon from the start of the reaction to the end of the reaction.

If you look at this graph you will see that at the begining of the graph it rises very steeply. The change from Hydrogen to Helium looks about 10MEV. This energy has to go somewhere and it's released as heat and light.

At around Iron the graph flattens out and then slowly starts to decend. Uranium sits right down at the bottom tail of the graph. Energy is released in fission because the end products sit further up the curve than Uranium.

Per reaction, Uranium fission produces a lot more energy than Hydrogen. Fission release around 250MeV and fusion releases around 17.6MeV. So why do we get so much additional power from a Hygrogen bomb? Well one mole of Uranium weighs 238 grams. In contrast, one mole of hydrogen weighs only 1 gram. The conclusion? We have a lot more hydrogen atoms per unit mass than we do Uranium. This means that we get 17 times more energy per unit kilogram than we do from Uranium . This is the reason the primary power source for the Hydrogen bomb is the Hydrogen and not the Uranium starter charge.

Simon.

The Hubble is being eclipsed by newer technology. It only makes sense to take the focus off of it. It is unfortunate that tax money is not spent more wisely by the government, but with recent successes by NASA, it makes sense to focus on future projects.

there is more information contained in a Hubble image like this than there is in a ground-based image taken by the most powerful telescope on Earth (Keck)

Really? VLT telescope produces images as sharp as Hubble

From what I recall hearing recently (though I can't find any articles, maybe someone can either dispute this for me or back it up?), growing plants on the moon for food or even oxygen isn't the most viable thing in the world. With a 28 day long day/night cycle, the darkness would be far too long for plants to survive.

Even to provide light for a large greenhouse during the lunar nights (not to mention maintain a constant temperature during this cycle that ranges from -180 C to 110 C would be an enormous amount. I suppose a nuclear reactor would provide enough power for something like that, I don't know enough about the energy requirements of a moonbase to even speculate.

I do think a base on the moon would be an extreme benefit to science however and is definitely a step in the right direction in terms of space exploration.

hmm well i googled for closest stars and got

30 closest stars

all of which are well below 65 light years. maybe they are listening...

There's Ironbridge Gorge if you like historical engineering stuff - it's name comes from the cast iron beridge that was built across the gorge in 1779. It was where modern iron-working was developed.
In London, there's the Thames barrier - a major part of London's flood defences, the Science Museum, the Royal Observatory in Greenwich, the spot that longitude is measured from and where the worlds timezones are based on (any pedants who want to reply to this pointing outthat an average of a collection of atomic clocks throughout the world is now used will get slapped and told to bugger off and stop being such an annoying pedantic twat...) There's also London Open House, which is more of an architecture thing really, and is mostly only for one weekend a year, but they do have events all year round.

There are a number of fascinating museums and sites in the UK that chronical the industrial revolution. Start at Ironbridge which is literally where it all started - the first industrial scale ironworks were here. Also take in the National Railway Museum in York which details the rise and development of the railways. The Science Museum in London is a more general review of science and industry, but includes some fascinating exhibits on (mainly British) science of that time. Finally - representing an earlier pivotal period - is the Greenwich Royal Observatory also in London that tells the story of the development of accurate clocks that allowed global navigation and exploration.

The UK is full of historical sites of that era, when Britain lead the world in science and industry. A historically-inclined geek's paradise.

One of the most accurate watches ever made was made in the 1700's by a man named John Harrison, in order to fix longitude.

Quite interesting story, actually. A quick search on Google turned up this page about how John Harrison solved the longitude problem. A true engineer!

You couldn't be more wrong if you tried. You could try, but you'd fail.

My, aren't we hostile!

Yes, the Prime Meridian (0 0' 0") ...

What, one zero wasn't enough for you?

... situated at the Royal Observatory and Planetarium (that's its correct name) ...

Sorry, your magical Google powers failed you this time. The Prime Meridian runs right through the Old Royal Naval Observatory. The buildings have been inactive since 1998 and under the control of the National Maritime Museum.

... but its adoption as the international standard has nothing to do with the invention of the "naval chronometer" by John Harrison in 1735.

It had everything to do with Harrison's naval chronometer. King Charles II founded the Royal Observatory in 1675 to solve the problem of finding longitude at sea. [cite] Harrison's chronometer was the first instrument which managed this, and for quite a while, the British had exclusive use of it. This allowed them to produce vastly more accurate nautical charts than everyone else. Since they were British charts, they used the British Prime Meridian. Since they were vastly more accurate than all other charts at the time, any sea navigator who could get his hands on them would have used them instead of their domestic naval charts, and very quickly nearly all naval charts in use put the prime meridian through the British Royal Naval Observatory.

I'll let the Observatory's own pages tell the story: ... [large block quote] ...

By the time of the conference, the British Prime Meridian already was The Prime Meridian in all but name, and had been for over a century.

So, it was an internationally agreed meridian, not an imperically imposed one.

Incorrect, it was an empirically determined meridian that eventually the rest of the political world accepted.

... The Prime Meridian for the world was adopted in 1884 ... One of the main reasons why Greewich was chosen over its rivals (including the French alternative of a meridian running through the centre of the Eiffel Tower) ...

Impossible. Construction of the Eiffel Tower did not even start until 1887, so how could it be used as a landmark for a prime meridian in 1884?

Perhaps, next time, you'll check the historical facts before you start giving history lessons.

Perhaps next time, you will realize the ability to type in Prime Meridian into a search engine does not make up for a complete and total lack of understanding about the subject.

Actually it is the British who decided where 0 degrees longitude was, and thereby the Eastern/Western hemispheres. Why do you think it runs through Greenwich Englind? If an American had first invented the Naval Chronometer instead of Harrison, 0 degrees longitude would run through Washington D.C. or New York City, and not the British Royal Naval Observatory.

You couldn't be more wrong if you tried. You could try, but you'd fail.

Yes, the Prime Meridian (0 0' 0"), is situated at the Royal Observatory and Planetarium (that's its correct name), but its adoption as the international standard has nothing to do with the invention of the "naval chronometer" by John Harrison in 1735.

I'll let the Observatory's own pages tell the story:

Until the nineteenth century, each country tended to keep its own zero meridian. The Prime Meridian for the world was adopted in 1884, at the International Meridian Conference in Washington DC. Twenty-five countries were represented and voted to adopt the Meridian at Greenwich as the Prime Meridian for the world. It was also agreed that longitude would be measured in two directions from the Prime Meridian, 'east longitude being plus and west longitude being minus.'

In 1960, shortly after the transfer of the Royal Greenwich Observatory to Herstmonceux (and, later, Cambridge), Flamsteed House was transferred to the National Maritime Museum's care and over the next ten years the remaining buildings on the site were also transferred. Here the collections of scientific, especially astronomical, instruments has continued to grow. Following the closure of the RGO at Cambridge in October 1998, the site is now known as the Royal Observatory Greenwich.

So, it was an internationally agreed meridian, not an imperically imposed one.

One of the main reasons why Greewich was chosen over its rivals (including the French alternative of a meridian running through the centre of the Eiffel Tower) was that Greenwich time was widely used worldwide by many industries.

Most notably, it was the standard time by which all US railroads ran their timetables. Rather than adopting yet another time system, the railroad operators preferred sticking to their existing standard for obvious reasons (familiarity and cost).

Perhaps, next time, you'll check the historical facts before you start giving history lessons.

Posting the story just as the Slashdot clock passes midnight is a nice touch. Except that it kind of spoils the effect for those of us who live west of Greenwich Observatory and thus see a post time of March 31.

The Museum is in Greenwich England...I don't remember what its longitiude is

The Museum is in Greenwich England...I don't remember what its longitiude is

If anyone is interested in accuracy in time keeping, a trip to the Royal Observatory in Grenwich is a must for you. You can see Huygens' parabolic pendulum located there.

Get to know about John Harrison, who made the first 'accurate' timekeeper, for use at sea to measure longitude. See Harrisons first accurate time peices of the world, H1 thru H4, where H1-H3 still ticks today.

A must is to stand on the prime meridian of the world, which represents 0 degree longitude, also located there. At night, a green laser can be seen streaking across the sky marking the zero parallel.

Check out the Royal Observatory, you won't regret it!

The moon distance measurement is obviously good. It seeks to do something no one else has ever achived. Even if the results aren't interesting, the new techniques used are. Anyone that doesn't see its intrinsic value is shortsighted.

The moon distance measurement is obviously good. It seeks to do something no one else has ever achived. Even if the results aren't interesting, the new techniques used are. Anyone that doesn't see its intrinsic value is shortsighted.

The start and end of daylight saving time is now standardized across the EU. According to http://www.rog.nmm.ac.uk/leaflets/summer/summer.ht ml , summer time starts at 01:00 on the last Sunday in March, and ends at 01:00 on the last Sunday in October. (That's 01:00 UT (01:00 GMT) in both cases, BTW.) This has been the case since 1998. I believe that this is decided at EU level: when France wanted to change timezone, the other EU countries (except Britain) refused to allow them to change.

I wrote code to handle this nonsense: uk_tz.pl. It's a few routines building on the Date::Manip Perl module - one day I should make it into a derived class, or something. Consider it GPL/Artistic dual-licensed.

This is absolutely no big deal- in fact I see it as a good thing.

For starters, DNA is not the solver-of-all-crimes it is put up to be.

DNA tests can simply say who has touched an object, NOT WHEN.

All it is used for is to whittle down a list of suspects.

In other words, DNA tests are used to EXCLUDE people from crimes, not include them.

I look forward to the day when DNA samples are taken at birth and I can happily forget all my passwords and keys.

I reckon the UK govt should offer prize money (as per the Longitude Prize for an ocean-going clock a few hundred years ago) to the first people to invent a DNA testing machine that fits inside a shoe box, can identify accurate to 1 in 100 million people, can outwit most forgery (eg. dead limbs), and can provide results in under 10 seconds.

Such a magic box could replace all locks, signatures and passwords.

--

I read this book a while ago, and was thoroughly entranced by the story. I wish I could remember more details, but the thing I remember most is this.

If you take a look at the four timepieces that Harrison built, you'll be floored by the final result. The book says something like: "However, when people see H4, they are stopped dead in their tracks."

It really is astounding. H1 looks like an early prototype. It looks as though, if you shook it, pieces would fly in all directions. H2 has the appearance of a later prototype-- much more rugged. It's starting to look like something that can be taken out to sea. H3 looks a little like H2, but with some fancier components added. H4, however, is, nothing less than a work of art. It's so completely different that you wonder what the point of the other three was.

One must have a great deal of respect for a man who, when he sees a better way, drops everything that he's been working on, and follows the new direction. Be it genius or recklessness, one must respect the way he followed his objective, as opposed to his own work.

--

Longitude was a great read, and I thought it was wonderful that a book essentially about engineering was so widely read. The book was inspired by the "Longitude Symposium" held in 1993. That symposium has to get the award for the snazziest proceedings ever: (they came out a couple years after the book) The Quest for Longitude : The Proceedings of the Longitude Symposium Harvard University, Cambridge, Massachusetts November 4-6, 1993. William J. H. Andrewes (Editor). You can see some pictures of Harrison's machines at Britain's National Maritime Museum , but Dava Sobel is a much better storyteller, so you'll enjoy reading Longitude more if you avoid reading the text at the museum site. On the other hand, the story of Rupert Gould, who restored Harrison's clocks, isn't told in Sobel's book. It was told in an awful soapumentary on cable this fall, but four hours was far far too long.

Longitude was a great read, and I thought it was wonderful that a book essentially about engineering was so widely read. The book was inspired by the "Longitude Symposium" held in 1993. That symposium has to get the award for the snazziest proceedings ever: (they came out a couple years after the book) The Quest for Longitude : The Proceedings of the Longitude Symposium Harvard University, Cambridge, Massachusetts November 4-6, 1993. William J. H. Andrewes (Editor). You can see some pictures of Harrison's machines at Britain's National Maritime Museum , but Dava Sobel is a much better storyteller, so you'll enjoy reading Longitude more if you avoid reading the text at the museum site. On the other hand, the story of Rupert Gould, who restored Harrison's clocks, isn't told in Sobel's book. It was told in an awful soapumentary on cable this fall, but four hours was far far too long.

I don't think that's why there aren't any gas giants in the inner solar system. Jupiter is pretty big, I doubt that you could really affect it by being too close to a star going through "teething problems".

This and this link should give you some good information. The first one is for the Modern Laplacian Theory, which is my personal favorite, and the second gives some quick information on some other formation theories, and talks a little bit about Bode's law.

I saw somewhere else that people were talking about vulcan. If memory serves, I think that vulcan was the name given to the planet inside mercurys orbit. This planet was predicted by using Bode's law, and searched for in the 1800's (I think?). I guess it was a kind of cold fusion of the day :)
__

the United States Naval Observatory

the Royal Greenwich Observatory

It matters because you cannot arbitrarily drop years from centuries or millennia and still have a functional calendar everyone can use. We have thousands of books of history based on each century encompassing years 1-100 inclusive. If you decide the 20th Century ends at the end of 1999, then which past century loses the year? (Only 1999 years have passed in the Gregorian calendar.)

If you change something like the method that time is measured or counted by, without unilaterally implementing it as a standard, you cause pervasive problems. As far as i am aware, there has been no world-wide agreement or even a Papal Bull from the Vatican (who created the Gregorian calendar) to short the 20th Century one year.