Timekeeping (Clocks, Horology, Methods, Standards, etc.)

A

Anonymous

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#1
Shortest time interval measured

Scientists claim they have measured the shortest interval of time ever.
Researchers used short pulses of laser light to produce images of electrons leaving atoms and recorded what happened to within 100 attoseconds.

To imagine how long this is, if 100 attoseconds is stretched so that it lasts one second, one second would last 300 million years on the same scale.

Scientists used the technique to record the dynamics of electrons in atoms and report their findings in Nature.

The research team employed extreme ultraviolet (XUV) light pulses to excite atoms, prompting them to emit electrons, the small negatively charged particles that are a fundamental part of every atom.

"We accelerate the electrons spinning around the nucleus. Some pick up so much energy that they leave the atoms forever," Professor Ferenc Krausz, of the Technische Universitat Wien, in Austria, told BBC News Online.

Future clocks

At the same time, the scientists used a device called a Few-Cycle Laser to capture "tomographic images" of these electrons that gave information about how they behaved with time.

This allowed the scientists to distinguish events within 100 attoseconds, the shortest interval of time ever recorded.

The advance opens up the possibility of more accurate timekeeping.

Existing atomic clocks are very accurate and measure time by counting the number of times caesium atoms jump back and forth between different energy levels.

These jumps, or "ticks", occur at microwave frequencies. But researchers are increasingly looking to count ticks using optical frequencies, with the help of lasers.

This would offer the prospect of more stable and therefore more accurate clocks.

"The more stable the clock, the better you can measure time," said Dale Henderson of the UK's National Physical Laboratory.
http://news.bbc.co.uk/1/hi/sci/tech/3486160.stm

Interesting...
 

tzb57r

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#2
Does anyone know what impact this will have on the theory of quantised time? I read somewhere that time is quantised at about 10^-34 seconds. It was a Physics teacher who got published in Nature about a year back.
 
A

Anonymous

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#5
Is the scaling in the initial article correct then.

1 attosecond if scaled up to one second, would result in 30 billion (US) year seconds (curious way of delineating the scalar in the article btw... I wonder if its been directly measured or can only be measured in clumps of 100 :) )
 

Graylien

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#6
Before TV and Radio, how did people know what time to set their clocks and watches to? And would 6pm in, say, London have been the same as 6pm in Leeds?

This has been bugging me all day.
 
A

Anonymous

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#7
I vaguely recall that time was only standardised across the country when railways becames widespread. Before that, 6pm might well have been slightly different in London and Leeds.

This could however be the rememberences of a diseased memory.
 

liveinabin

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#9
foxybox said:
I vaguely recall that time was only standardised across the country when railways becames widespread. Before that, 6pm might well have been slightly different in London and Leeds.

This could however be the rememberences of a diseased memory.
You are quite correct. A man from London was on holiday in Dorset. He missed his train home because his watch was set to London time which was half an hour behind. If you use sundials it depends on when the sun is directly overhead. this vairies depending on your poition in the country.

I guess before the railways it didn't matter much. The only people you would make appointments with would be local.
 

rjmrjmrjm

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#10
Many places also had what the called '1 o'clock guns'. i.e. a cannon that would fire at 1pm every day.

This reminds me of a funny story about a traveller in Switzerland. He was descending a mountain into a small isolated valley when he came accross a small fort with some soilders setting up a gun facing the valley. He inquired into what they were doing and they told him every day they fired a blank shot at 1 o'clock to tell people in the local villages and hamlets the time because very few people in the area had a clock. The man was puzzled and asked how the soliders knew what time it was. The sergeant told the man to follow him. They walked up the hillside a while until they came to a rocky outcrop that overlooked the entire vally. The soilder pointed to a town in the distance and said that that town was the only one in the area that had a clock and he used his telescope to see what time the clock said and tell his men when to fire.

Later that day the man had descended into the vally and followed the river past numerous small hamlets until he came to the town. He was sitting near the clocktower when the caretaker came. The man asked the caretaker about the clock and was told how old it was and that the town had bought it from Bern. When the man asked how the caretaker managed to keep it on time he smiled and said: 'Oh its perfectly simple! The lads on the hill fire a gun at one every day!'
 

jarmaniac

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#12
rjm said:
Many places also had what the called '1 o'clock guns'. i.e. a cannon that would fire at 1pm every day.
Edinburgh still has one, or did when I lived there (early 1990s). The joke was that you could spot the tourists from Northern Ireland because they were the ones who threw themselves flat onto the pavement at one o'clock...
 
A

Anonymous

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#13
Apparently my home town of Ellesmere Port (yes, I know, but we all have to come from somewhere) is 1 and a half minutes behind Greenwich Mean Time (is that how you spell it??)

A fact our geography/history teacher had great pleasure informing us of on a Friday afternoon when we were waiting to go home (that we would go home on GMT not EPT)
 

WhistlingJack

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#14
Bluebottle: What time is it Eccles?

Eccles: Err, just a minute. I've got it written down on a piece of paper. A nice man wrote the time down for me this morning.

Bluebottle: Ooooh, then why do you carry it around with you Eccles?

Eccles: Well, um, if a anybody asks me the time, I can show it to dem.

Bluebottle: Wait a minute Eccles, my good man.

Eccles: What is it fellow?

Bluebottle: It's writted on this bit of paper, what is eight o'clock, is writted.

Eccles: I know that my good fellow. That's right, um, when I asked the fella to write it down, it was eight o'clock.

Bluebottle: Well then. Supposing when somebody asks you the time, it isn't eight o'clock?

Eccles: Well den, I don't show it to 'em.

Bluebottle: Ooohhh.

Eccles: [smacks lips] yeah.

Bluebottle: Well how do you know when it's eight o'clock?

Eccles: I've got it written down on a piece of paper.

Bluebottle: Ohh, I wish I could afford a piece of paper with the time written on.

Eccles: Oohhhh.

Bluebottle: 'Ere Eccles?

Eccles: Yah.

Bluebottle: Let me hold that piece of paper to my ear would you? 'Ere. This piece of paper ain't goin'

Eccles: What? I've been sold a forgery.

Bluebottle: No wonder it stopped at eight o'clock.

Eccles: Oh dear.

Bluebottle: You should get one of them tings my Grandad's got.

Eccles: Oooohhh.

Bluebottle: His firm give it to him when he retired.

Eccles: Oooohhh.

Bluebottle: It's one of dem tings what it is that wakes you up at eight o'clock, boils the kettil, and pours a cuppa tea.

Eccles: Ohhh yeah. What's it called? Um.

Bluebottle: My Granma.

Eccles: Ohh. Ohh, wait a minute. How does she know when it's eight o'clock.

Bluebottle: She's got it written down on a piece of paper.


The Mysterious Punch-Up-the-Conker
 

Leaferne

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#15
Canada may consider daylight time change

CTV.ca News Staff

Canada may have no choice but to follow a move by the United States to extend daylight saving time, which could come into effect this year, says a business leader.

"Obviously, the Canadian economy and the U.S. economy are so integrated now that for us to be out of sync with one another I think will cause some severe problems," Len Crispino, president and CEO of the Ontario Chamber of Commerce told CTV Newsnet.

The U.S. Congress quietly signed off on a provision Tuesday to extend daylight saving time hours by two months. It would begin on the first weekend in March, and end the last weekend in November.

The neighbouring countries currently follow the same daylight time -- from the first Sunday in April to the last Sunday in October. There are some exceptions, such as Saskatchewan, which keeps its clock the same all year round.

The provision to change daylight saving time is a clause in the Energy Policy Bill of 2005. The congressmen who sponsored the change -- Michigan's Fred Upton and Massachusetts's Ed Markey -- say it could help curb energy use.

If U.S. President George Bush signs the bill, the law could come into effect this fall -- causing potential headaches for travellers, businesses and TV viewers this November.

Implications on industry

The change could have implications for many business and industries in Canada, including on Bay St., where the Toronto Stock Exchange would open and close one hour after New York's markets for part of the year.

Crispino said the automotive sector would also be affected, since many automotive manufacturers use "just in time" delivery systems to get car parts to plants.

"To be out of sync will cause some real difficulties and will add some costs to it," he said.

Other businesses that would be affected include the aviation industry. Being out of sync with most of the world's clocks could mean millions lost in valuable time slots -- the time when planes can land or take off.

Crispino said he doesn't think Canadian industry is ready for such a change, and believes the government was caught off guard.

"If there was a delay, I think that would be helpful. My sense is there will probably not be a delay and that we will probably be forced into synchronizing with the U.S. system."

Provinces react

Alberta is taking a wait-and-see approach to the U.S. proposal.

Government spokesman Shannon Haggarty says Alberta will be consulting with other provinces on the issue, but at this point there's no plan to make any changes.

Ontario Premier Dalton McGuinty says the province is examining the pros and cons of extending daylight savings time. He says Ontario doesn't want difficulties with its main trading partner, but there are environment, business, and social issues to consider before the province follows suit.

"What are the environmental ups and downs of this? What are the business pros and cons? And then what about life for families? Does it make it more or less difficult?" McGuinty said.

"We're going to have to take a look at it, obviously."

Ontarians can email the government to let politicians know what they think of the idea. The email address is [email protected]

But Manitoba Premier Gary Doer supports the move to extend daylight time. Doer says business will encounter problems if Canada does not follow suit.

He also says going along with the change would have a modest impact on energy conservation in Manitoba.
Source
 

lemonpie3

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#16
It would have been nice if the US had consulted with the people most likely to be affected by the changes. But it's probably unrealistic not to go along with it. Doesn't it cause problems for Saskatchewan?
 

Anome

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#17
Why don't they just move their time zone forward an hour and be done with it? Is there really anything to be gained by only being on "Standard Time" for 3 months of the year.

We already extended ours to complement the Northern Hemisphere. Runs from End of October to End of March.
 
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#19
Shifting meridians: a tale of time

By Jerome Weatherald
BBC Radio Four


In Shifting Meridians on BBC Radio 4, the British explorer Benedict Allen has been uncovering the riddles of the world time zone map. Producer Jerome Weatherald found the history of time head-scratchingly mysterious.


Millennium Island, Kiribati; first place to experience the year 2000
Most of us know that France is an hour ahead of the UK, New York is five hours behind, and Australia - well, 10 or something hours ahead.

But in terms of global time, that kind of knowledge does not even scratch the surface of the complexities and curiosities of the different time zones around the world.

How about this for starters. China, that vast country that stretches across five hour zones on a globe, has only one time zone - Beijing time, to the east. Yet Russia has 11, and the USA five.

The UK shares a time zone with Portugal, the Canary Islands and the majority of western Africa - but not with France and Spain, both of which sit on the same Greenwich Meridian which is the basis for UK clocks, Greenwich Mean Time (GMT).

India reportedly snubbed its former rulers by choosing to be five and a half hours ahead of GMT ("turn your watch upside down if you're in the UK, and that's the time in India", the saying goes); and what is Nepal doing on GMT plus four and three-quarter hours?

Dog legs

Five years ago the explorer Benedict Allen embarked on a solo trek across the arctic wastes of eastern Russia with a team of dogs in an attempt to cross the Bering Strait to Alaska.


Benedict Allen began pondering time zones while on floating ice
As the ice began to break up, he found himself adrift on a block of ice unintentionally going backwards and forwards across the International Date Line, not knowing whether it was today, tomorrow or yesterday.

This got him thinking about how time, as well as geography, has come to define our place on the planet.

One look at a time zone map of the world reveals a globe carved up like a child's jigsaw. No two pieces are the same; there are no straight lines connecting the North and South Pole.

Some pieces are so small you can barely see them; others crash into each other in defiance of the beauty of the longitudinal lines that divide the world into 24 perfect segments.

So what lies behind this extraordinary document, and what does it reveal?

Revolutions


BBC NEWS: VIDEO AND AUDIO
Listen to Shifting Meridians
The International Meridian Conference of 1884 established Greenwich as the Prime Meridian, zero degrees longitude. But that proved to be the starting gun for a major re-organisation of the globe.
Countries were free to choose whatever time they wanted, regardless of the position of the Sun and its relationship to the clock on the wall.

Broadly organising themselves along the longitudes established by Greenwich, countries soon realised that time is power. For example, after initially opting for five time zones, in the Chinese Revolution of 1949 the authorities in Beijing symbolically adopted a single time zone dictating time across their vast country.

One effect of this was that on one side of the Afghanistan-China border it is GMT plus four and a half, while just over the border in China it is three and a half hours later (fancy starting work when the clock says 3am, anyone?)


The world time zone map is a living, ever-changing beast. The island nation of Kiribati on the equator used to straddle the International Date Line, meaning that half of its islands were a day ahead of the others.

In 1995 they decided to align themselves with the time in Asia, creating a finger on the International Date Line extending thousands of miles to the east into yesterday, as it were.

The squiggles and dog-legs in the South Pacific deserve a whole programme to themselves.

You would think there would be 24 time zones across the world. But at the last count there were 39.

"One of the most preposterous things that an alien would find coming from Mars and landing on Earth is that our time zones have no rhyme or reason," says professor of theoretical physics Michio Kaku.

"Any Martian would say how silly humans are that they can't even decide what time it is, which is one of the most basic aspects of being civilised."


You can listen to Shifting Meridians at Radio 4's Listen again page. The programme was broadcast on Sunday 21 May.
http://www.bbc.co.uk/radio4/progs/listenagain.shtml


http://news.bbc.co.uk/1/hi/sci/tech/4995194.stm
 
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#20
Published online: 26 January 2007; | doi:10.1038/news060122-12

No time for British clock changes
Daylight-saving measure fails to gain enough support.
Michael Hopkin


The British parliament voted against setting the clocks on the same time as the rest of Europe.


A plan to bring Britain's clocks into line with those in the rest of Europe has failed to gather the necessary political support. The potential change, championed by supporters as a way to save lives and energy, will now be dropped.

The measure would have given Britain an extra hour of evening daylight in both winter and summer, by advancing the clocks an hour ahead of their current times while continuing to observe 'daylight saving time' (DST) by moving them forward in spring and back in autumn.

A 26 January vote in the British parliament failed to draw the necessary 100 members needed for the measure to proceed to the next stage, of committee evaluation. Only 52 members voted, with 32 backing the bill.

Preliminary calculations suggest that the move could have saved around 100 lives a year through reducing evening traffic accidents, and around £485 million (US$950 million) in energy costs (see 'Saving time')

The United States is set to extend its own DST regime by four weeks this summer — clocks will go forward on 11 March instead of during the first week of April, and will not be set back until November. Power companies' figures show that peak demand for lighting is during the evening darkness rather than in the morning, so putting the clocks forward generally cuts overall power use.

The British plan was more ambitious, proposing a permanent shift forward for clocks rather than a simple extension of summer hours. As a result, the move met with concern from some politicians, that the resulting dark winter mornings could affect farmers and construction workers.

"The argument went very much in favour of the bill," said member of parliament Tim Yeo, who proposed the measure. "But the threshold of 100 members is a significant obstacle."

The government refused to give official backing to the bill, which may explain the low turnout. A previous experiment with extending summer time in Britain between 1968 and 1971 was abandoned, in part because of complaints from Scottish politicians that the change made winter mornings too dark in the north, putting schoolchildren at risk.


Story from [email protected]:
http://news.nature.com//news/2007/070122/070122-12.html
 

Peripart

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#21
I don't know why they keep resurrecting this plan - it'll never see the light of day.
 
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#22
Peripart said:
I don't know why they keep resurrecting this plan - it'll never see the light of day.
Har har!

But:

29 January 1848 Greenwich Mean Time was adopted by Scotland.

So this is the appropriate day to discuss such matters.
 
A

Anonymous

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#23
I've never understood the arguement about the clocks affecting farmers. If its light then they can farm, if its dark then they can't. What difference does the time make?
 

Peripart

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#24
It's not the farmers themselves, it's the sheep. They're very easily confused.
 
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#25
Peripart said:
It's not the farmers themselves, it's the sheep. They're very easily confused.
It is the farmers. They wont be able to find the sheep for their nefarious purposes on dark mornings.
 

rynner2

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#26
Amazingly, a search for a thread with the word Time in the title comes up with nothing! And yet search for "Time Travel" turns up dozens of threads!
(Well, I guess weird things happen on a Fortean MB!)

And yet this almost undefinable concept of Time is at the root of all science and daily life. So here's a thread to discuss Time, in practise and theory.

To kick off, this:

Digital watches help trains run like clockwork
Helen Carter
Tuesday November 13, 2007
The Guardian

If you are on a windswept platform wondering if the train is on time, good news is on the way: staff at Northern Rail are synchronising their watches.
The operator, with commuter services throughout the north of England, has issued 3,000 staff with digital watches, updated via a signal from the UK's new time signal at Anthorn in Cumbria. The time is displayed in a digital format, which, it is hoped, will assist with punctuality.

The benefit will be felt at Liverpool Lime Street. The station has a very rapid turnaround between services, and any train a few minutes late in the morning has a domino effect through the day.
Rob Warnes, performance and planning director at Northern Rail, said: "Seconds can be crucial to making sure that our 2,500 daily trains keep their time slots on an increasingly congested rail network. Our employees were previously using their own watches which they updated by checking with the speaking clock. The new watches are a big advantage because they are updated automatically.

"A delay of just a few seconds at the start of a journey can mean that the train is late arriving at its destination, and that can cause delays to other services."

Northern Rail carries 77 million passengers a year - 20% more than when they first started the franchise three years ago. Punctuality has increased from 84% three years ago to 88% over the last 12 months.

In January, the east coast train operator GNER distributed radio-controlled watches to 1,000 frontline staff, after research showed that watches used by train dispatchers could vary by as much as 90 seconds.

At Network Rail's annual general meeting in Manchester this year, it emerged that a total of 10.5m minutes on the rail network had been lost in the last year, largely due to copper cable theft and adverse weather. Each lost minute cost the company an average of £10.

Rail unions have welcomed the investment but said the money could be better spent on improved rolling stock, which would improve punctuality and train reliability.

http://www.guardian.co.uk/transport/Sto ... 29,00.html

Students of the history of Time will know that it was the railways which gave us, in Britain, a unified time zone. Before the railways arrived, each town had its own local time, based on the mean movement of the sun, but this caused timetable problems on long east-to-west journies. (eg: Cornwall is about 20 minutes behind London according to mean solar time.)
 

TinFinger

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#27
Digital watches help trains run like clockwork ... lol

once read a good book called "about time" cant remmeber the author but it was about einsteins contribution to the debate of the nature of time.

have always thought that quantum physics is more a study of the time the waves/particals exsist in rather than said matter/energy itself.a sort of indirect look at the nature of time,like the efect magntes have on iron filings

just my 2 cents(which is also an odd saying)
 

OneWingedBird

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#29
Sounds like a nice way of ramping up the stress for the rail workers while doing nothing to improve what they have to work with...

...i'm all for punctuality, but holding human beings to that sort of timescale is expecting them to behave like automata :(
 

TinFinger

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#30
i hate watches

i dont see how time is so important that you need it strapped to your wrist,ok your a scuba diver...
 
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