4 ms·

I really wonder how we’ll use that mega-accurate clock that takes like a second every gazillion years. Like the article said, GPS is great but even then you don

by Ecco 6y ago

I really wonder how we’ll use that mega-accurate clock that takes like a second every gazillion years. Like the article said, GPS is great but even then you don’t need such accuracy.

garmaine 6y ago
All the time in certain kinds of lab work.
wahern 6y ago
Improved gravimetric geodesy? https://arxiv.org/pdf/1803.01585.pdf https://arxiv.org/pdf/1803.01585.pdf
- jhayward 6y ago
  That's a nice overview paper. There is much value in the gravimetric mapping realm and we're not even close to the limits of what people are imagining. For instance, by combining multiple ultra-precise orbiting clocks with quantum teleportation networks linking them for time transfer one could gravimetrically map the planet in 3D at millimeter resolutions. E.g.: these clocks would be able to carefully map the shape of Earth’s terrain down to the millimeter. “You’d be able to see someone digging a tunnel under the U.S.-Mexico border from space” [1] One other capability of such a system: whoever possessed it would be able to locate every single significant concentration of dense matter, e.g., plutonium on the planet no matter where it was stored. They would know exactly how many nuclear weapons, etc. everyone had and exactly where they were keeping them. [1] https://www.sciencenews.org/article/quantum-timekeeping https://www.sciencenews.org/article/quantum-timekeeping (paywall)
m-ee 6y ago
Calibrating slightly less accurate clocks. What those clocks are used for I have no idea, but there’s times you need a good traceable measurement for some calibration of your own and your uncertainty stack can start to add up. The better, smaller, and cheaper NISTs equipment is the better your local cal lab will be and the easier your work is. Try finding a thermometer setup that’s better than 1 degree accurate from 0-400C. It might be more than you expect. Now imagine you want to measure some property of a sensor or material as function of temperature using your new thermometer, add in the cost of an oil baths and precision multimeters. Now say you want to create your own golden standard with the best precision you can muster, your expensive oil bath is looking lacking and you’re buying Vienna mean standard ocean water...
- TooKool4This 6y ago
  Well said. The ability to better realize primary standards and disseminate that to secondary metrology labs from national standards is so critical. It’s the same reason I think the work done in changing the SI definition to physical constants is so critical. In a decade or so all secondary labs should have capabilities to measure directly to the definition of a unit without needing to do comparison measurements to national standards. To me it seems like the metrology equivalent of “open sourcing SI units”
  - m-ee 6y ago
    It's important work and it can be surprisingly easy to run into the limits of your uncertainty. If you ask someone to measure a temperature in my experience 9/10 times they'll grab a type K thermocouple. Far fewer than 9/10 will tell you that the number they gave you is only guaranteed to be +/-3 degrees. That's good enough for a lot of applications but not all of them, and when something is really critical it helps to understand the full stack if your supplier/lab/coworker is making questionable claims about their accuracy.
TooKool4This 6y ago
Specific to my knowledge base, timing is critical to applications in inertial sensors (IMUs that guide missiles, AR/VR, smartphone apps, and so much more). To that end, here is interesting work that DARPA is doing in developing inertial sensors that can navigate without GPS for significant amounts of time. Critical to that is accurate chip level atomic clocks. https://www.darpa.mil/program/micro-technology-for-positioning-navigation-and-timing https://www.darpa.mil/program/micro-technology-for-positioni... Other uses as other posters mentioned is in traceability of measurements. Improving the means of measurement of the primary standard has downstream impact to secondary standards in metrology labs which ultimately (through transfer standards) would result in better calibrations of production systems. Finally, an interesting thought I have is that in the future this could be an interesting way to figure out your absolute position on Earth. At a conference one of the NIST Boulder folks mentioned that the frequency of clocks in the development pipeline was so precise/stable that it could pick up time dilation effects from moving the clock from a desk to the floor! An instrument like that combined with accurate gravimetery data could be used to map the earth, find concentrations of natural resources, or possibly act as a standalone positioning system. It’s a chicken and egg problem though. I don’t know if we will know all the uses for it until we build it, so instead of saying “why build it?” I think it makes sense to go and just build it :)
- throw0101a 6y ago
  > […] downstream impact to secondary standards in metrology labs which ultimately (through transfer standards) would result in better calibrations of production systems. What is a "transfer standard"? Can you name an example(s)?
  - jhayward 6y ago
    A transfer standard is an artifact that is produced at a standards laboratory to be sent to another laboratory for the purpose of calibration of the 2nd laboratory's processes and equipment. "Measurement Assurance Programs are quality control programs for calibrating a customer's entire measurement system. In a typical MAP, a stable artifact or set of artifacts called transfer standards are first measured by NIST and then sent to a customer's laboratory for a series of measurements. The transfer standards are then returned to NIST for re-measurement, along with the participating laboratory's results. NIST reports its comparative findings to the customer and, when necessary, offers guidance on achieving and maintaining measurement quality. Successful use of a NIST MAP requires that the customer make periodic measurements of in-house check standards to estimate their measurement process uncertainty and to ensure that the measurement process remains in a state of statistical control. Unless a laboratory has a measurement quality assurance program to monitor its own measurement process parameters continuously, there is no value in participating in a MAP. In fact, NIST recommends that its customers establish and use a measurement quality assurance program to monitor their measurement parameters, whether or not they participate in a MAP." [1] https://www.nist.gov/calibrations/policies#:~:text=In%20a%20typical%20MAP%2C%20a,with%20the%20participating%20laboratory's%20results https://www.nist.gov/calibrations/policies#:~:text=In%20a%20....
fanf2 6y ago
Time and frequency are to a large extent the basis of most of our measurement technology and our system of units. The metre is defined based on the speed of light. It is realized using interferometry, for which you need lasers of precisely calibrated frequency. Voltage is measured using Josephson junctions and a calibrated frequency. The new definition of the kg is based on a Kibble balance (aka a watt balance) which relies on measuring position, current, and voltage, all of which rely on precise frequency. If you look at the summary diagram of the new SI system https://en.wikipedia.org/wiki/2019_redefinition_of_the_SI_base_units https://en.wikipedia.org/wiki/2019_redefinition_of_the_SI_ba... you can see that all the base units depend on the second (except the mol).

by Ecco 6y ago

I really wonder how we’ll use that mega-accurate clock that takes like a second every gazillion years. Like the article said, GPS is great but even then you don’t need such accuracy.

garmaine 6y ago

All the time in certain kinds of lab work.

wahern 6y ago

Improved gravimetric geodesy? https://arxiv.org/pdf/1803.01585.pdf https://arxiv.org/pdf/1803.01585.pdf

jhayward 6y ago
That's a nice overview paper. There is much value in the gravimetric mapping realm and we're not even close to the limits of what people are imagining. For instance, by combining multiple ultra-precise orbiting clocks with quantum teleportation networks linking them for time transfer one could gravimetrically map the planet in 3D at millimeter resolutions. E.g.: these clocks would be able to carefully map the shape of Earth’s terrain down to the millimeter. “You’d be able to see someone digging a tunnel under the U.S.-Mexico border from space” [1] One other capability of such a system: whoever possessed it would be able to locate every single significant concentration of dense matter, e.g., plutonium on the planet no matter where it was stored. They would know exactly how many nuclear weapons, etc. everyone had and exactly where they were keeping them. [1] https://www.sciencenews.org/article/quantum-timekeeping https://www.sciencenews.org/article/quantum-timekeeping (paywall)

m-ee 6y ago

Calibrating slightly less accurate clocks. What those clocks are used for I have no idea, but there’s times you need a good traceable measurement for some calibration of your own and your uncertainty stack can start to add up. The better, smaller, and cheaper NISTs equipment is the better your local cal lab will be and the easier your work is. Try finding a thermometer setup that’s better than 1 degree accurate from 0-400C. It might be more than you expect. Now imagine you want to measure some property of a sensor or material as function of temperature using your new thermometer, add in the cost of an oil baths and precision multimeters. Now say you want to create your own golden standard with the best precision you can muster, your expensive oil bath is looking lacking and you’re buying Vienna mean standard ocean water...

TooKool4This 6y ago
Well said. The ability to better realize primary standards and disseminate that to secondary metrology labs from national standards is so critical. It’s the same reason I think the work done in changing the SI definition to physical constants is so critical. In a decade or so all secondary labs should have capabilities to measure directly to the definition of a unit without needing to do comparison measurements to national standards. To me it seems like the metrology equivalent of “open sourcing SI units”
- m-ee 6y ago
  It's important work and it can be surprisingly easy to run into the limits of your uncertainty. If you ask someone to measure a temperature in my experience 9/10 times they'll grab a type K thermocouple. Far fewer than 9/10 will tell you that the number they gave you is only guaranteed to be +/-3 degrees. That's good enough for a lot of applications but not all of them, and when something is really critical it helps to understand the full stack if your supplier/lab/coworker is making questionable claims about their accuracy.

TooKool4This 6y ago

Specific to my knowledge base, timing is critical to applications in inertial sensors (IMUs that guide missiles, AR/VR, smartphone apps, and so much more). To that end, here is interesting work that DARPA is doing in developing inertial sensors that can navigate without GPS for significant amounts of time. Critical to that is accurate chip level atomic clocks. https://www.darpa.mil/program/micro-technology-for-positioning-navigation-and-timing https://www.darpa.mil/program/micro-technology-for-positioni... Other uses as other posters mentioned is in traceability of measurements. Improving the means of measurement of the primary standard has downstream impact to secondary standards in metrology labs which ultimately (through transfer standards) would result in better calibrations of production systems. Finally, an interesting thought I have is that in the future this could be an interesting way to figure out your absolute position on Earth. At a conference one of the NIST Boulder folks mentioned that the frequency of clocks in the development pipeline was so precise/stable that it could pick up time dilation effects from moving the clock from a desk to the floor! An instrument like that combined with accurate gravimetery data could be used to map the earth, find concentrations of natural resources, or possibly act as a standalone positioning system. It’s a chicken and egg problem though. I don’t know if we will know all the uses for it until we build it, so instead of saying “why build it?” I think it makes sense to go and just build it :)

throw0101a 6y ago
> […] downstream impact to secondary standards in metrology labs which ultimately (through transfer standards) would result in better calibrations of production systems. What is a "transfer standard"? Can you name an example(s)?
- jhayward 6y ago
  A transfer standard is an artifact that is produced at a standards laboratory to be sent to another laboratory for the purpose of calibration of the 2nd laboratory's processes and equipment. "Measurement Assurance Programs are quality control programs for calibrating a customer's entire measurement system. In a typical MAP, a stable artifact or set of artifacts called transfer standards are first measured by NIST and then sent to a customer's laboratory for a series of measurements. The transfer standards are then returned to NIST for re-measurement, along with the participating laboratory's results. NIST reports its comparative findings to the customer and, when necessary, offers guidance on achieving and maintaining measurement quality. Successful use of a NIST MAP requires that the customer make periodic measurements of in-house check standards to estimate their measurement process uncertainty and to ensure that the measurement process remains in a state of statistical control. Unless a laboratory has a measurement quality assurance program to monitor its own measurement process parameters continuously, there is no value in participating in a MAP. In fact, NIST recommends that its customers establish and use a measurement quality assurance program to monitor their measurement parameters, whether or not they participate in a MAP." [1] https://www.nist.gov/calibrations/policies#:~:text=In%20a%20typical%20MAP%2C%20a,with%20the%20participating%20laboratory's%20results https://www.nist.gov/calibrations/policies#:~:text=In%20a%20....

fanf2 6y ago

Time and frequency are to a large extent the basis of most of our measurement technology and our system of units. The metre is defined based on the speed of light. It is realized using interferometry, for which you need lasers of precisely calibrated frequency. Voltage is measured using Josephson junctions and a calibrated frequency. The new definition of the kg is based on a Kibble balance (aka a watt balance) which relies on measuring position, current, and voltage, all of which rely on precise frequency. If you look at the summary diagram of the new SI system https://en.wikipedia.org/wiki/2019_redefinition_of_the_SI_base_units https://en.wikipedia.org/wiki/2019_redefinition_of_the_SI_ba... you can see that all the base units depend on the second (except the mol).