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Single-Ion Clock 100 Times More Accurate Than Atomic Clock

timothy posted more than 2 years ago | from the so-now-you're-really-late dept.

Australia 169

New submitter labnet writes with this excerpt from news.com.au: "University of New South Wales School of Physics professor Victor Flambaum has found a method of timekeeping nearly 100 times more accurate than the best atomic clocks. By using the orbit of a neutron around an atomic nucleus he says the system stays accurate to within 1/20th of a second over billions of years. Although perhaps not for daily use, the technology could prove valuable in science experiments where chronological accuracy is paramount, Prof Flambaum said."

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yeah but (4, Funny)

Anonymous Coward | more than 2 years ago | (#39337925)

until it comes with indiglo i don't want it

Eventually... (5, Interesting)

Anonymous Coward | more than 2 years ago | (#39337947)

Eventually you'll be so accurate that walking by the thing will cause enough relativistic distortions that you can no longer claim to have any accuracy at all.

Re:Eventually... (5, Funny)

Bowdie (11884) | more than 2 years ago | (#39338045)

Grr! You changed the clock by observing it!

Damm kids!

Re:Eventually... (0)

Anonymous Coward | more than 2 years ago | (#39338443)

What time is it? I can't tell you. Why?

Re:Eventually... (4, Funny)

K. S. Kyosuke (729550) | more than 2 years ago | (#39338937)

The summary is misleading at best anyway:

Although perhaps not for daily use, the technology could prove valuable in science experiments where chronological accuracy is paramount, Prof Flambaum said.

As the different series of Star Trek have already shown us, the words "chronological accuracy" and "Paramount" do not belong to the same sentence, much less do they deserve to be joined by the copula.

Re:Eventually... (0)

Anonymous Coward | more than 2 years ago | (#39339123)

What time is it?

Let me see... D'oh!

Re:Eventually... (4, Informative)

gomiam (587421) | more than 2 years ago | (#39338063)

It's even worse. IIRC, current atomic clocks are now so precise that stacking one on top of the other (say 20cm distance) is enough to make them start drifting due to the different gravitational field strength.

Re:Eventually... (4, Funny)

Yvan256 (722131) | more than 2 years ago | (#39338093)

So what you're saying is that by stacking a few dozen alarm clocks on top of each other, I can get one more hour of sleep?

Cool!

Re:Eventually... (4, Funny)

zAPPzAPP (1207370) | more than 2 years ago | (#39338349)

The only flaw in this plan is, that you would need to sleep through all alarms but the last one.
Other than that it's perfect.
Yes.

Re:Eventually... (0)

Pope (17780) | more than 2 years ago | (#39338531)

It's clocks all the way down...

Re:Eventually... (0)

Anonymous Coward | more than 2 years ago | (#39338423)

Stacking? How many of those freakin' things do you have laying around?!

Re:Eventually... (2)

necro81 (917438) | more than 2 years ago | (#39338631)

Stacking any two clocks on top of each other would cause them to drift due to relativistic effects. The only reason atomic clocks are special in this regard is that you can actually measure the effect over the course of something less than a few million years.

Umm, no. (0)

Anonymous Coward | more than 2 years ago | (#39339597)

Yes, there will be relativistic drift, but the clocks won't be accurate enough to detect it. Lets say the relativistic drift is actually pretty enormous, 1 second per year, and your two average desk clocks drift by up to 1 second per day, or six minutes per year. The random noise will tend to cancel itself out, so after a year the desk clocks will likely still be within a minute or so of "true", but they could be as much as twelve minutes apart if one ran consistently fast and the other consistently slow, and there's no telling which will be which.

So how exactly are you supposed to use them to measure the 1 second difference due to time dilation? You can't, the signal is lost in the noise. You could perhaps put a few thousand clocks in each location and do statistical analysis do discover there was 0.7+/-0.5 seconds of relativistic drift over the course of the year, but that's a different beast entirely. And in the postulated scenario of stacked atomic clocks you're probably talking less than a picosecond of drift per year, you can't fit enough desk cocks in the building for statistics to tease the signal out of that noise.

Re:Eventually... (2)

CastrTroy (595695) | more than 2 years ago | (#39338809)

Isn't the rotation of the earth, shifting of the continental plates, movement of their earth around the sun, and any other movement throwing off the clock. Actually how does one define "not moving". Moving is always relative to something else. If I stand still, I'm not moving relative to the ground, but I am moving relative to the sun, which is moving relative to the galaxy, which is moving relative to all the other galaxies. Is there a scientfic definition of "not moving" that doesn't use other objects as a reference?

Re:Eventually... (0)

Anonymous Coward | more than 2 years ago | (#39339765)

Yes - pick any point that's moving in a perfectly straight line at a perfectly constant speed in perfectly flat space. That point is not moving. The identical point that just whizzed past in the opposite direction? That point is also not moving, in its equally valid inertial reference frame. That's one of the fundamental principles of relativity. Any point that's accelerating - speeding up, slowing down, following a curved path like an orbit or point on a spinning object, etc. *is* moving and does not provide an inertial reference frame, i.e. it will exhibit "ghost forces" such as the "centrifugal force" that pushes you against the door in a turning car. No such force exists, it only appears to because you're measuring relative to the car, which is experiencing the opposite force.

Re:Eventually... (1)

fishicist (777318) | more than 2 years ago | (#39339425)

Citation for the parent: http://www.sciencemag.org/content/329/5999/ [sciencemag.org]

n.b. the work [1] by Müller, Chu et al is related, but different, and the interpretation is strongly contested (e.g. [2])
[1] http://newscenter.berkeley.edu/2010/02/17/gravitational_redshift/ [berkeley.edu]
[2] http://www.nature.com/nature/journal/v467/n7311/full/nature09340.html [nature.com]

Re:Eventually... (5, Informative)

huge (52607) | more than 2 years ago | (#39338163)

As the old saying goes: "A man with one clock knows what time it is. A man with two clocks is never sure."

Re:Eventually... (3, Insightful)

strack (1051390) | more than 2 years ago | (#39338421)

a man with three clocks knows if one of his clocks is not working correctly.

Re:Eventually... (3, Insightful)

ArsenneLupin (766289) | more than 2 years ago | (#39338543)

a man with three clocks knows if one of his clocks is not working correctly.

So does a man with two clocks. But a man with three clocks may know which one.

Re:Eventually... (1)

CastrTroy (595695) | more than 2 years ago | (#39338719)

Only if there is only 1 clock wrong. Also if there are 2 clocks wrong by the same amount, the owner of the three clocks would be wrong in assuming that the third with a different time was wrong, when in fact it did have the right time.

Re:Eventually... (0)

Anonymous Coward | more than 2 years ago | (#39339349)

Well I guess he's talking about different types of clocks, which means they have no reason to be wrong by the same amount, which means they can only be wrong by the same amount due to luck. What is the probability that two independent real numbers are the same?

Re:Eventually... (2)

TheRaven64 (641858) | more than 2 years ago | (#39338773)

No, he is just more confident in his guess as to which one.

Re:Eventually... (2)

Quietust (205670) | more than 2 years ago | (#39338863)

A man with three clocks will invariably find some convoluted way of using them to tell the time:

"This one runs ten minutes slow every two hours. This runs twenty minutes fast every four hours. The one in the middle is broken and stopped at two o'clock. I take the ten minutes on this one and subtract it from the twenty minutes on that one. Then I divide by the two in the middle."

Re:Eventually... (1)

PerfectionLost (1004287) | more than 2 years ago | (#39339207)

Or the other one: "Even a stopped clock is right twice a day."

Re:Eventually... (2)

Junta (36770) | more than 2 years ago | (#39339287)

Not if it is digital

Re:Eventually... (2)

Baloroth (2370816) | more than 2 years ago | (#39339431)

Actually it still will be. Those old VCRs that used to flash 12:00? A stopped digital clock, right twice a day.

Now, if the digital clock is broken, and not merely stopped, such that it cannot display anything, it will never be either right or wrong.

Re:Eventually... (1)

Joce640k (829181) | more than 2 years ago | (#39338259)

I could be wrong but isn't the definition of one second based on some atomic phenomenon? (All the sloshing water and wind makes the revolution of the planet a non-starter...)

How can a new method be more accurate than the method we use to define time?

Re:Eventually... (2)

bhtooefr (649901) | more than 2 years ago | (#39338419)

Because the measurement used to define time drifts slightly.

The second used to be defined based on the Earth's rotation, but cesium atomic clocks became so much more accurate than the earth itself, that the standard was changed to be based on the behavior of a cesium atom. The standard can always be changed again.

Re:Eventually... (2)

vlm (69642) | more than 2 years ago | (#39338439)

I could be wrong but isn't the definition of one second based on some atomic phenomenon? (All the sloshing water and wind makes the revolution of the planet a non-starter...)

How can a new method be more accurate than the method we use to define time?

jitter phenomena. Aka phase noise. You'd like to think something like a Rb clock watches exactly one atom and counts that single atom, but its a lot more analog than that.

Man you has one clock knows what time it is, as you say. Man who has two clocks has no freaking idea what time it is. Man who has at least three clocks and lets ntpd or equivalent do its thing for a couple days/weeks has excellent idea what time it is and how accurate each clock is relative to "the group".

Dual purpose- (1)

way2trivial (601132) | more than 2 years ago | (#39338607)

at which point will use it for a RND seed generator

Re:Eventually... (1)

Rhacman (1528815) | more than 2 years ago | (#39339001)

It will still maintain that accuracy, just within its own inertial frame of reference. As long as the scientists using the clock are able to account for this in their experimental setup and analytical models then they should be able to retain that accuracy.

Just scientific experiments? (4, Interesting)

gcnaddict (841664) | more than 2 years ago | (#39337967)

Although perhaps not for daily use, the technology could prove valuable in science experiments

You kidding me? The prospect of GPS-guided bullets accurate to the millimeter will have the US military pursuing this in next-gen GPS satellites as soon as the technology is viable. Hell, this'll be the most valuable update to military hardware in decades.

Re:Just scientific experiments? (1)

erotic_pie (796522) | more than 2 years ago | (#39338081)

If I remember correctly, GPS will be difficult to get much more accurate than it is today to the time distortions caused by relativity. Once a clock gets this accurate the relativistic distortion between the sattellite in space and the user on the ground becomes too great. That is of course if they don't find a workaround to the problem.

Re:Just scientific experiments? (2)

definate (876684) | more than 2 years ago | (#39338267)

I'd have thought that such a "distortion", which would just be relativistic differences, and as such would be somewhat constant or predictable. At the very least, over time they should be able to, estimate the amount of "distortion", which would likely mean they would get more and more accurate over time, as they improve this prediction algorithm. Additionally, if more satellites are added to the field, and perhaps if the protocol also better supported geographically fixed transmitters, you could further eliminate these problems.

Re:Just scientific experiments? (4, Interesting)

gcnaddict (841664) | more than 2 years ago | (#39338303)

That's precisely what hyper-accurate atomic clocks allow you to correct. The distortions manifest in less accurate clocks. The more accurate your time, the better your algorithmic corrections between the ground and the satellites.

Re:Just scientific experiments? (1)

JamesP (688957) | more than 2 years ago | (#39338961)

For "hyper-precision" you would probably have to account for transportation velocities/times

It's the twin paradox but with microseconds of difference.

Or re-sync them in place which is very complicated to do as well.

Re:Just scientific experiments? (1)

pnewhook (788591) | more than 2 years ago | (#39338487)

GPS satellites already have to take into account the relativistic effects of their motion. This is not new.

Re:Just scientific experiments? (2)

ArsenneLupin (766289) | more than 2 years ago | (#39338581)

GPS satellites already have to take into account the relativistic effects of their motion. This is not new.

Right now, they "only" meed to take into account relativistic effects due to the satellite's speed, or due to the lower gravity at their altitude. What is new is that this new clock is so sensitive that it would need to take into account the relativistic effects due to the small amount of gravity caused by passing trucks...

The former is easily modelizable (and can thus be compensated for), whereas the later isn't.

Re:Just scientific experiments? (1)

fnj (64210) | more than 2 years ago | (#39338535)

GPS already has to take account of both general and special relativity. It wouldn't be much good if it didn't.

Re:Just scientific experiments? (1)

WrongSizeGlass (838941) | more than 2 years ago | (#39338169)

Although perhaps not for daily use, the technology could prove valuable in science experiments

You kidding me? The prospect of GPS-guided bullets accurate to the millimeter will have the US military pursuing this in next-gen GPS satellites as soon as the technology is viable. Hell, this'll be the most valuable update to military hardware in decades.

I really don't think the distance a GPS-guided bullet travels will require the additional accuracy provided by this new clock. If your target is moving so fast that you need more accuracy than an atomic clock provides then you shouldn't be using a bullet.

Re:Just scientific experiments? (1)

rossdee (243626) | more than 2 years ago | (#39338265)

I think that a laser guided bullet would be more likely to work given that GPS targeting is not so good at hitting moving targets.

Re:Just scientific experiments? (0)

Anonymous Coward | more than 2 years ago | (#39338365)

And in the future we say: drop a bullet from the orbit. Its the only way to be sure.

Re:Just scientific experiments? (1)

MiniMike (234881) | more than 2 years ago | (#39338557)

Although perhaps not for daily use, ...

You kidding me? The prospect of GPS-guided bullets accurate to the millimeter ....

Snipe much?

Re:Just scientific experiments? (1)

Pope (17780) | more than 2 years ago | (#39338641)

Have you been watching "Runaway" again?

This is the worst article ever (1)

Anonymous Coward | more than 2 years ago | (#39337973)

Could, could, could, could. Just a method of timekeeping that *could* be used, but has many issues. How about an post on warp drives next?

Re:This is the worst article ever (2)

WrongSizeGlass (838941) | more than 2 years ago | (#39338275)

Could, could, could, could. Just a method of timekeeping that *could* be used, but has many issues. How about an post on warp drives next?

New discoveries, breakthroughs and technologies have potential until they are actually used. Once they are used then they need to prove the projections correct. By today's "everything changes so fast it's hard to keep up without a clock that's more accurate than an atomic clock" standards these things aren't new anymore by the time they've been proven useful (or useless).

Re:This is the worst article ever (0)

Anonymous Coward | more than 2 years ago | (#39338289)

I read that as "Cloud cloud cloud cloud" and heartily agreed.

Re:This is the worst article ever (1)

Yvan256 (722131) | more than 2 years ago | (#39338801)

How about an post on warp drives next?

Okay sure, no problem.

I installed OS/2 Warp on my hard drive.

Are you happy now?

Great! But... (1)

Anonymous Coward | more than 2 years ago | (#39337985)

...what is the point of this?

Genuinely. I'm seriously interested. I want to know the kind of science which requires timings of this accuracy. I think they must be some really exciting experiments to be studying phenomena on that short a timescale.

Re:Great! But... (1)

WrongSizeGlass (838941) | more than 2 years ago | (#39338187)

...what is the point of this?

Genuinely. I'm seriously interested. I want to know the kind of science which requires timings of this accuracy. I think they must be some really exciting experiments to be studying phenomena on that short a timescale.

Maybe those guys who thought they measured something traveling faster than the speed of light could use a more accurate clock (not to mention a better plug) ;-)

Re:Great! But... (2)

tibit (1762298) | more than 2 years ago | (#39338279)

A whole lot of science and engineering needs this. We have communication networks that give us ability to distriute experiments and measurements, but a lot of those aren't very useful without a very precise time reference; the networks, as they are, are quite poor at distributing time. Examples: suppose you want to measure time-of-flight of particles across the globe (neutrinos or otherwise); large base telescope (whether radio or optical); more accurate global positioning. The prerequisite in all cases is an ultra-accurate timebase. In fact, large base optical telescopes will require very stable and accurate distributed local oscillators (heterodynes), lack of one is one of the reasons why we don't have optical-to-RF heterodynes for imaging; RF-to-RF heterodynes, even distributed ones, are nothing new and are used for radioastronomy all the time -- optical ones are hard because you need orders of magnitude better clock source in terms of phase noise and drift.

Re:Great! But... (1)

cupantae (1304123) | more than 2 years ago | (#39339033)

Maybe YOU don't need it, but some of us have real jobs and need to know where to be, down to the femtosecond.
I would have had to wind my old clock in a few hundred million years, but after I get one of these babies, I won't have to.

observations change time? (1, Interesting)

Anonymous Coward | more than 2 years ago | (#39338011)

Wouldn't "reading" the time change the orbit of the neutron?

Re:observations change time? (1)

CaptainJeff (731782) | more than 2 years ago | (#39338143)

No. Wavefunction collapse [wikipedia.org] has already occurred.

1/20th?? (3, Funny)

MrP- (45616) | more than 2 years ago | (#39338019)

"1/20th of a second over billions of years."

As an omnipotent being I demand better precision!

Link to actual paper (5, Informative)

foo1752 (555890) | more than 2 years ago | (#39338039)

Re:Link to actual paper (1)

FirstOne (193462) | more than 2 years ago | (#39339791)

Hmm, It looks like the clock isn't as accurate as claimed..

It's based on measuring a single atom of Th229 which has a half life of 7340 years.. So every so often your new fancy ion clock is going to randomly drop dead. (Unless you have multiple units and are comparing the outputs..) Then you need to isolate a steady supply of ionized Th-229 (which is a decay product from U-233, 160KY) to repair the dead modules.

Orbit of neutron around the nucleus? (4, Interesting)

michelcolman (1208008) | more than 2 years ago | (#39338043)

And here I was, thinking that neutrons were inside the nucleus and electrons were orbiting around it. What's going on here? How can a neutron orbit a nucleus? It's an actual question, I know the atomic models I was once taught are way out of date (by a couple of centuries, probably), but I never heard of neutrons orbiting nuclei.

Re:Orbit of neutron around the nucleus? (5, Informative)

CaptainJeff (731782) | more than 2 years ago | (#39338091)

Here you go. Nuclear Shell Model [wikipedia.org]

Re:Orbit of neutron around the nucleus? (1)

vivek_bye (1138507) | more than 2 years ago | (#39338233)

and which clock do they use to calculate how fast the neutron goes around the neucleus?

Re:Orbit of neutron around the nucleus? (3, Funny)

fnj (64210) | more than 2 years ago | (#39338517)

Thanks a lot. Now I am disturbed. Everybody knows the nucleus is a bunch of little round colored balls globbed together.

Re:Orbit of neutron around the nucleus? (2)

mark99 (459508) | more than 2 years ago | (#39338615)

Thanks. I almost puked when I read the word "orbit".

Re:Orbit of neutron around the nucleus? (0)

Anonymous Coward | more than 2 years ago | (#39339929)

Correct; this is what was meant in the original paper. The article got it wrong when it said the neutron is orbiting around the nucleus; rather it's orbiting inside the nucleus much like electrons are orbiting inside the atom's electron cloud. And orbiting has to be understood in a decidedly quantum mechanical sense.

Orbit around a nucleus? (1)

ngc5194 (847747) | more than 2 years ago | (#39338049)

It was my understanding that since the rejection of the Bohr model of the atom that we didn't think electrons "orbited" an atomic nucleus, that they were "smeared out" throughout their energy levels. What am I missing?

Re:Orbit around a nucleus? (3, Insightful)

CaptainJeff (731782) | more than 2 years ago | (#39338115)

Nothing. Modern physics is unable to describe how electrons really work/interact with other subatomic particles in a way that makes sense. Which the orbiting isn't right, the shell model isn't right either...we're just not able to describe it yet. So, one model can be an effective description for certain purposes and others for others. In this case, the Nuclear Shell Model [wikipedia.org] describes a different model of the atomic nucleus that describes the quantum interactions in a manner that allows these types of measurements to be made.

Re:Orbit around a nucleus? (3, Interesting)

tibit (1762298) | more than 2 years ago | (#39338343)

The term "making sense" is, I believe, misapplied here. The quantum world is pretty much unavailable to our senses, neither do they exactly teach this stuff to kindergartners. So we have no early-life experience of any sort here, thus there's no common sense about the world at quantum scale. It won't ever make sense, and there's no reason for it to make any sense. It's just how the world happens to work, and there's nothing at all that we can do about it. This is in stark contrast to, say, bureaucracy, where certain ways of doing stuff are not how Nature works, but how humans happen to work -- very changeable if you can pull it off.

Re:Orbit around a nucleus? (1)

necro81 (917438) | more than 2 years ago | (#39338789)

Modern physics is unable to describe how electrons really work/interact with other subatomic particles in a way that makes sense.

What do you mean by "makes sense?" We can describe the interaction of electrons with other subatomic particles to more-or-less arbitrary precision (better than we can measure in experiments, anyway). There are some subatomic interactions that can be predicted, using QED/QCD, out to 10+ decimal places, and subsequently confirmed by experiment. Clearly the modern physics description made pretty good sense to those who developed the theory, made the prediction, then designed and executed the experiments. What is more, it can be described qualitatively to anyone curious over the course of a few lectures. Whether it "makes sense" to the general population in a way that, say, our experience with falling rocks allows us to make (some) sense of gravity is, I would argue, irrelevant.

Who said that the structure of the universe (or, rather, our descriptions thereof) should "make sense" and jive with our experience and intuition? We ended up stuck with geocentricism for thousands of years because of that reasoning.

since a neutron is so small (1)

FudRucker (866063) | more than 2 years ago | (#39338069)

why cant i buy a wristwatch with this technology built in it?

If You Need That Much Accuracy (4, Informative)

Greyfox (87712) | more than 2 years ago | (#39338097)

It's very easy to fuck it up, as we saw with the FTL neutreno experiment a few months ago. I've seen a lot of business requirements specify that level of precision because they think it would be cool and it just turns into a nightmare later. Hell, you're lucky to agree within tens of seconds. Take POSIX (PLEASE! Heh.) POSIX specifies that time measured in seconds from midnight, Jan 1, 1970 UTC. Seams easy enough right? Well it turns out UTC specifies accounting for leap seconds, so you should subtract 33 seconds (IIRC) over the course of those 42 years. POSIX also specifies that leap seconds not be accounted for. Brilliant! Then it's not UTC! Now here's where it gets fun! The Linux kernel may or may not actually handle leap seconds, depending on how you configure it. And what happens if you're syncing off NTP? Or GPS? It's a problem if you need to convert to TAI or TDT. If you adjust for leap seconds and your system doesn't measure them, you could end up being over 60 seconds wrong versus what time it "really" is. When you're trying to communicate with a satellite going 2000 miles a second, that's a problem. Because you'll be pointing you're antenna over there, and the satellite's really over here!

It'd be nice if some physics professor *cough* could solve those problems before making some shit that can be accurate for a billion years! See what I did there? That was just passive aggressive right there, wasn't it? Too much Portal, lately...

Sadly, I'll never know ... (1)

gstoddart (321705) | more than 2 years ago | (#39338121)

I can't even get my atomic watch to set properly from the time signal that exists now.

I must be too far from Denver for the signal to get to my watch. Which sucks, since it defeats the whole purpose of having that.

Re:Sadly, I'll never know ... (1)

tibit (1762298) | more than 2 years ago | (#39338417)

Your watch is probably doing a rather lame decoding of the signal. Good receivers directly digitize the incoming signal, do filtering and demodulation numerically, and can correlate it with a model signal over minutes or even hours to get a lock. A friend of mine, a real RF nerd, has made such a receiver and it works where you can't even see the damn signal on a spectrum analyzer, with a decent antenna, on the narrowest bandwidth setting (10 or 15Hz IIRC). I think it routinely worked for him when he was staying in Cape Horn and even a couple hundred miles northeast from there for a couple of months.

Re:Sadly, I'll never know ... (1)

gstoddart (321705) | more than 2 years ago | (#39338457)

Your watch is probably doing a rather lame decoding of the signal.

Yeah, I figured that part out. :-P

It's a relatively inexpensive Casio, so it's not like I expected a great amount of technology.

Was just a little bummed that it has rarely (if ever) been able to set from the atomic signal -- that was supposed to be the cool part, and what I could use as a baseline to keep my other watches set correctly.

Re:Sadly, I'll never know ... (1)

fnj (64210) | more than 2 years ago | (#39338565)

Agreed. Sheesh, you'd think they could afford to raise the power of the signal, or add more sites.

How do you measure how accurate it is? (3, Insightful)

Viol8 (599362) | more than 2 years ago | (#39338153)

If an atomic clock is your most accurate timepiece then how on earth can you tell if something is more accurate?

Can someone explain?

Also , given that a second is defined in terms of the ceasium atom as used in atomic clocks then surely anything that deviates from this is by definition LESS accurate (if you see what I mean)?

Re:How do you measure how accurate it is? (1)

rossdee (243626) | more than 2 years ago | (#39338321)

If the accuracy is defined as fractions of a second over billion years - how do they know its going to last a billion years

Re:How do you measure how accurate it is? (3, Insightful)

vlm (69642) | more than 2 years ago | (#39338583)

If the accuracy is defined as fractions of a second over billion years - how do they know its going to last a billion years

Run the reciprocal and test your frequency. You know that saying about how in europe they think hundreds of miles (err KM) is far away and hundreds of years is recent, but in the US they think hundreds of miles is a daily commute and hundreds of years is ancient? Well billions of seconds is a long time, but billions of cycles per second is actually medium to low frequency in the RF world now a days, depending I guess on industry (that would still be considered kind of fast in the PLC/VFD field, but truly ancient great-grandfatherly stuff in the radar world)

So you've got three atomic clocks (now a days a ebay special Rb clock is about $100 surplus) and use that to drive three sets of ham radio microwave experimenters gear at 10 GHz (which is not cutting edge anymore). Hmm. 10 billion hz. suddenly fractional parts per billion becomes fractional hz which a piano tuner has no real problem detecting.

This isn't exactly how it works, but as a thought experiment you hook up your 10gig ethernet and drive it with this clock and hack the driver for variable length packets... If you think you have better than 0.1 ppb clock, then you should be able to transmit a billion bit packet and not fall out of frame sync (which at 10 gigs only takes a tenth of a second). This is not exactly the modulation method used by real 10gigE and not exactly how you test it, but it within the realm of the general idea.

Good luck doing modern ham radio stuff like bouncing microwave signals off the moon using the more exotic low SNR digital modes without at least PPB level frequency accuracy. Freq stability is a factor at 10 GHz until at least 10e-9 for that kind of work... luckily 10e-11 is cheap and off the (ebay) shelf for $200 or so GPSDO or old Rb oscillators.

Re:How do you measure how accurate it is? (0)

Anonymous Coward | more than 2 years ago | (#39338455)

"If an atomic clock is your most accurate timepiece then how on earth can you tell if something is more accurate?"

I'm just guessing, but maybe it's http://en.wikipedia.org/wiki/Mathematical_proof [wikipedia.org]
"Proofs are obtained from deductive reasoning, rather than from inductive or empirical arguments."

Re:How do you measure how accurate it is? (3, Insightful)

tibit (1762298) | more than 2 years ago | (#39338539)

The same way it always was. Think of how you'd do it in any sort of mechanical measurements. You don't need the same level of accuracy to determine that something is more accurate. Most measurements have nice properties that must hold when you repeat the measurements, such as linearity. All you have to do, then, is to use the assumedly more accurate device to characterize the errors of a less accurate one. If you can reproduce your results and various expected properties hold, then there's no other explanation but that your new device is in fact more accurate.

The deal with the caesium atom is that it only defines a second to a certain accuracy. If you have a better time reference, it's not by definition less accurate, it's just that your standard has accuracy only to so many decimal digits and when you're past that you must get a better standard. You can use the better reference to characterize the inaccuracies in your standard (say various drifts, phase noise in case of time references, etc). Eventually, you redefine the second using the better standard, and you do it pretty much by appending some arbitrarily chosen digits to the new definition that reproduces the old one. They had second defined however, then they measured it using the caesium clock, got a bunch of results, averaged them, and said: that's the new second. A whole bunch of digits of the new definition were pretty arbitrary -- they original definition wasn't able to provide you with stable digits all the way. Same thing will happen again: the new clock will be used to measure the cesium one, and they'll average things and the new second will be a few orders of mangnitude more cycles of this nuclear clock; it will be matching the old clock within the old clock's accuracy, but the now-added digits will be entirely arbitrary. This is how it has happened with pretty much all the other measurements (distance, weight, etc).

Re:How do you measure how accurate it is? (2)

fishicist (777318) | more than 2 years ago | (#39338595)

1) You make two and see by how much they differ after a certain time. (Further reading, see Allan variance.)
2) As with all the base units, we must 'define' the second in terms of something physical, which we can measure, so that we can use this abstract idea in the real world. This real-world embodiment is imperfect, and it is an engineering challenge to make something which better approximates the idea. For illustration, consider the kilogram, which is defined by a lump of metal in Paris. In principle, chipping a bit off this block makes everything else weigh more in terms of kilograms, but we immediate recognise this as crazy and we can imagine a better physical embodiment of the ideal kilogram (indeed, efforts are under way to do just this). So it is with the second: the caesium clock is the best we've got so far, but it's just a physical embodiment of the ideal second, and we can strive to make a more accurate (with accuracy defined as in (1) above).

Re:How do you measure how accurate it is? (2)

Guppy06 (410832) | more than 2 years ago | (#39339057)

The most accurate timekeeper is actually a battery of atomic clocks, with an average taken (after all known relativistic distortions are accounted for), called TAI. If your new clock hews to that average better than the individual atomic clocks used to generate that average, it's more accurate.

Re:How do you measure how accurate it is? (1)

elsurexiste (1758620) | more than 2 years ago | (#39339363)

Wouldn't an average between all those clocks raise the standard deviation of the (granted) extremely precise measurement?

Wouldn't be better to just use a single clock?

Re:How do you measure how accurate it is? (1)

pavon (30274) | more than 2 years ago | (#39339749)

No, the average of independent measurements has a lower variance [wikipedia.org] than the individual measurements.

Re:How do you measure how accurate it is? (1)

rwise2112 (648849) | more than 2 years ago | (#39339625)

Well since the second is defined based upon atomic oscillation now,
secÂond 1 (sknd)
n.
1. Abbr. sec.
a. A unit of time equal to one sixtieth of a minute.
b. The time needed for a cesium-133 atom to perform 9,192,631,770 complete oscillations. See Table at measurement.
I can only see this as less accurate!

I have to say (3, Funny)

NEDHead (1651195) | more than 2 years ago | (#39338157)

It's about time

atomic clock accuracy (1)

vossman77 (300689) | more than 2 years ago | (#39338209)

Yes, because being off by 2 seconds every billion years is something to worry about. I am sick of having to adjust my watch for the inaccuracy of atomic clocks.

Re:atomic clock accuracy (4, Interesting)

vlm (69642) | more than 2 years ago | (#39338717)

Yes, because being off by 2 seconds every billion years is something to worry about. I am sick of having to adjust my watch for the inaccuracy of atomic clocks.

a OC-192 fiber line transmits 10 gigs/sec, roughly.

If you stuck one of those "2 secs/gigayear" clocks on each end, instead of regenerating the clock off the line, I think the circuit would lose line sync and drop every:

365*24*60*60 /10 /2 / 6/60/60/24 = every 18.2 days. Bummer.

Lets check. 10 gigabits/sec at 18.2 days is 18.2*24*60*60*10*1e9 is 1.57e16 bits. 2 secs/gigayear is an error rate of 1e9*365*24*60*60/2 is 1.57e16 bits per clock framing failure. Seems likely.

That is why now a days you get your clock off the line instead of internal clocking at each site. In ye olden T-1 era, a clock that good at each CO would mean you'd probably never experience a clock slip between COs in the lifetime of the equipment... Even in ye olden days we internal timed quite a bit (and some of our DEXCS only could do internal, so we had to)

Does the clock run Linux? (0)

Bryan-10021 (223345) | more than 2 years ago | (#39338219)

Isn't that really what /. people care about? Alien ship crashes from another galaxy. "Is the ship powered by Linux?"

Preprint on arXiv (4, Informative)

eis2718bob (659933) | more than 2 years ago | (#39338261)

A preprint is available on arXiv at http://arxiv.org/abs/1110.2490 [arxiv.org]

A nuclear transition in triply-ionized 229Th has been found which is particularly insensitive to external magnetic fields and electron configuration, which gives the potential for a very stable clock,several orders of magnitude better than current clocks if phase comparisons can be made across a scale of days or weeks. The transition energy is at 163nm (in the ultraviolet). To take advantage of this clock an extremely stable laser at this wavelength (using current best clocks) will need to be created.

Re:Preprint on arXiv (0)

Anonymous Coward | more than 2 years ago | (#39339053)

But Thorium-229 is radioactive with a period of about 7340 years. The period is in the range of nasty values, although it is only an alpha emitter which is easy to protect from, but the first product is 225Ra which is a beta- emitter with a half-life of 14.9 days giving 225Ac. In turn 225Ac is an alpha emitter with a half-life of 10 days resulting in 221Fr, decaying itself with a half-life of 4.8 minutes through alpha radiation into 217At.

At this point it becomes funnier since 217At has a very short half-life of 32 milliseconds and either decays into 213Bi through alpha emission (99.8%) or into 217Rn through beta- (0.12%). 217Rn decays into 213Po (alpha, 20 milliseconds), which transmutes immediately into 209Pb (alpha, 3.5 microseconds), which undergoes a final beta- decay into 209Bi, which has a long enough half life (1.9x10 years, giving stable 205Tl) to have been considered stable until 2003!

Back to the other branch 213Bi decays in 45.6 minutes wither into 213Po through beta- (97.9%), which brings back to the prevous chain, or into 209Tl. 209Tl has a half-life of 2.16 minutes decaying into 209Pb so we are back again to 209Bi.

Still, from 229Th to 209Bi, there are 5 stage of alpha emission and a few beta- decays in the path. Given the difference in decay rates, this is essentially equivalent to transmuting the original 229Th into 209Bi with a half-life of 7340 years.

However this means that the thorium in the initial experiment will grow quite a significant proportion of impurities after a few years. I suspect that the clock has more than one atom of thorium, but the changing composition of the system may be a problem.

How can you tell?? (3, Interesting)

mooingyak (720677) | more than 2 years ago | (#39338319)

I've always wondered, with regard to the accuracy of clocks like this, how can you actually tell how accurate it is?

Experimental work and some context (2)

fishicist (777318) | more than 2 years ago | (#39338333)

It's an exciting idea, and it's streaks ahead of 'traditional' microwave transition atomic clocks. These do not represent the state of the art, however, for which one should look at the experimentally demonstrated ~9e-18 accuracy by the Wineland group at NIST http://arxiv.org/abs/0911.4527v2 [arxiv.org] ; http://www.nist.gov/physlab/div847/grp10/ [nist.gov] , or the Strontium ion clocks at NPL (Teddington, UK) Essentially, the higher the frequency, the more clicks you get in a certain time, and the more accurate your clock can be (the smaller an error one missed click would represent). The caesium atomic clock is about 10 GHz (1E10 Hz). Strontium is in the optical, so a few 100THz (1E14). Aluminium ions are at about 1PHz (1E15 Hz). This new proposal with Thorium is around 7.6eV, which is about 2PHz, so not a million miles away from the current, demonstrated, state of the art. Also... orbit of the neutron around the nucleus isn't a fair description of a magnetic dipole transition, which would more accurately be describes as a flip in the direction of the neutron's spin axis. :)

Where is the obligatory FTL neutrino post? (2)

hcs_$reboot (1536101) | more than 2 years ago | (#39338555)

Can't find one even myself! Sounds like it's no fun anymore :-|

Flaumbaum! *shakes fist* (1)

Anonymous Coward | more than 2 years ago | (#39338593)

VERY cool for GPS if they ever upgrade the satellites... also, "Professor Victor Flaumbaum" is a badass name.

And yet (0)

Anonymous Coward | more than 2 years ago | (#39338621)

my wife will still insist that she's 39.

100 times more accurate? (3, Insightful)

sootman (158191) | more than 2 years ago | (#39338627)

If Server A has 90% uptime and Server B has 99% uptime, that does not mean that Server B is up 10x more than Server A, even though Server A is down 10x more than Server B. In fact, Server B is only 10% better than Server A. Or, 1/10 as bad.*

So, while the old clock may drift 100x more than this new one in a certain amount of time, or this new one might last 100x longer before drifting a certain amount (or whatever--the .au article is total puff and I don't care enough to look at the source), it is almost certainly not 100x more accurate. At best, it's 1/100th as inaccurate.

* The difference between 36 days of downtime per year versus 4 days might be the difference between "useful" and "completely worthless", making Server B 100x better, but that's not what we're measuring here.

1st attempt at /. car analogy (1)

Coisiche (2000870) | more than 2 years ago | (#39338753)

It all seems like an unnecessary gain.

Kind of like choosing a car that can reach 210mph over one that can only do 150mph when the national speed limit is only 70mph.

Yes, I know the figures don't show 100x but it just seems that it's pointlessly better than the currrent best clock which is already better than most people would ever need.

Re:1st attempt at /. car analogy (1)

bkaul01 (619795) | more than 2 years ago | (#39339267)

From TFS:

Although perhaps not for daily use, the technology could prove valuable in science experiments where chronological accuracy is paramount, Prof Flambaum said."

This isn't intended for "most people," but for very precise scientific experiments.

Accuracy measure (2)

Myopic (18616) | more than 2 years ago | (#39339173)

So, honest question, how do you measure the accuracy of the world's most accurate clock? I mean, what do you measure it against?

Oh! Great. more FTL now. (1)

140Mandak262Jamuna (970587) | more than 2 years ago | (#39339345)

Come on guys, more opportunities for Faster Than Light travel. May be not yet for mortals but for the particles shot through a tunnel in alps, all it takes is a few bad connections and some inaccurate clocks, and superluminal speed becomes a reality.
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