NIST Builds A 100,000 Times Better Atomic Clock

J Shumate writes: " NIST has built a better clock, which, no doubt, will lead to a better mouse trap." According to the article, "The new all-optical atomic clock -- so named because of its reliance on laser technology -- measures the shortest intervals of time ever recorded. In fact, those intervals are 100,000 times shorter than those observed by the best current clocks."

Comments

Re:Electronics?

[Anonymous Coward]

The effect to which you are referring (clock rates differ between ground and up in the air) is not a special relativity problem (i.e. relative speeds), but a general relativity problem. The clock rates differ because the one on the ground is deeper into the gravity well created by the earth's gravitational field. Such measurements were carried out in the early 1960's using Mossbauer effect driven clocks (that can resolve time durations down to about a part in 10^13 or so).

One would think that a claim to high precision would take this effect into account since gravitational wells do effect photons (light) - an effect first seen in the eclipse of 1919 (Einstein's great vindication).

Fun with relativistic effects

[K-Man]

Even motion at 1 m/s should yield time dilation of about 1 part in 10^17, which is only 100 times smaller than the ticks/s (10^15 = 1 quadrillion) of the clock. So walking the thing around for a about 100 sec. will yield a difference of one tick.

Anybody want to calculate the GR effects at different altitudes?

Re:Fun with relativistic effects

[K-Man]

OK, I got lazy and looked up some figures. At the Earth's surface, the gravitational time dilation for each km of altitude is 1 part in 10^-13 (source), or 100 ticks/s. This is a linear approximation, so that translates into 1 tick/s gained for each 10m of altitude.

Short Term vs. Long Term Stability

[Detritus]

Anyone know what the short term stability of this clock is? Last time I checked, masers beat cesium beam clocks for short term stability, which is important in some applications.

Re:accuracy

[thogard]

Pi seconds is about a nanocentury.

Re:Electronics?

[EasyTarget]

I dont get it, I had a quick look at the PARCS stuff and I cannot find any mention of relativistic effects..

However, they seem to be talking of comparing clocks which are moving at different speeds relative to each other. Presumably, given the sort of accuracy they are trying to achieve, these clocks will suffer signifigent relativistic drift from each other. I know that relativistic effects have been observed with a pair of clocks, one on the ground, and another in a Jet doing a large number of long trips. IIRC They actually confirmed the predicted relative time dilation effects by experiment that way.

Anyone know how PARCS addresses this..?

EZ

Re:Electronics?

[eclectro]

The Reuters report mentions that it takes up a couple of rooms. I would think that it takes pretty exotic equipment to constantly suspend the single ion of mecury so they could bounce lasers of from it.

I'm sure someday they will get all the laser/optical processing smaller, but it is probably isn't a priority right now. The most important use of accurate clocks will come from the PARCS project.

Millimeter GPS?

[Kadin2048]

So, if you had one of these clocks and put it in a GPS satellite, wouldn't it mean that you could get the GPS system that much more accurate? As I understand it, at the heart of GPS sats are atomic clocks; would more accurate clocks = more accurate positioning?