Finally, Will the "One Second" be Updated? The Day Optical Atomic Clocks Redefine World Time

Finally, Will the "One Second" be Updated? The Day Optical Atomic Clocks Redefine World Time

Is One Second No Longer Sustainable with Just "Cesium"?

We use time every day without questioning it. The clock on our smartphones, synchronization for transportation and broadcasting, timestamps for financial transactions, and satellite positioning. However, this "obvious accuracy" is built upon an invisible time infrastructure.


This time infrastructure may soon undergo a "change of the main standard." At the center of this discussion is the next-generation atomic clock using "light"—the optical atomic clock.


The article from Phys.org introduces how optical atomic clocks are approaching the stage of replacing the "definition of one second," and how their applications are expanding beyond just time measurement, based on a review paper.


Atomic Clocks Count "Atomic Reactions"

The principle of atomic clocks, simply put, is to "count the remarkably stable reactions (transitions) that atoms exhibit under specific conditions." The current "one second" is defined by the microwave transition of cesium-133 atoms. This has long been a "strong standard" supporting the foundation of science and technology.


However, optical atomic clocks use transitions in a higher frequency range—namely, the optical range. The higher the frequency, the finer the "ticks" within the same one second. It's like switching from a ruler with coarse markings to one with ultra-fine markings. The path to increased precision is prepared at the principle level.


The article explains that optical atomic clocks are composed of laser-cooled ions or atoms, and by repeatedly probing them with lasers, they create precise "time ticks" using the property of reacting only to that frequency.


From "Laboratory Monsters" to "Field-Deployable Instruments"

When thinking of optical atomic clocks, one might imagine huge optical tables, vacuum devices, and complex laser systems—such "laboratory monsters." However, the article emphasizes that optical atomic clocks are beginning to move "outside the laboratory."


The collaborative research team includes University of Adelaide, National Institute of Standards and Technology (NIST), and National Physical Laboratory (NPL), discussing how optical atomic clocks are more precise than traditional microwave atomic clocks and can "operate outside the laboratory."


This trend of "going outside" is not just about miniaturization. To redefine the time standard as a global standard, "the highest performance for just a moment in the laboratory" is not enough. It needs to be continuous, comparable, maintainable, and distributable—essentially, it must function as a part of social infrastructure. The challenges mentioned in the article, such as "continuous operation (many are intermittent)," "comparison and agreement," and "immature parts supply chain (high cost)," are inevitable.


Redefining "Second" Is Not Determined by Technology Alone

The article conveys the rapid progress of optical atomic clocks, suggesting that they could become the "gold standard within a few years" if conditions are met. However, the international "definition" update operates on a different timeline.


On the framework side managing the "second," the roadmap and consensus formation of BIPM are progressing. The FAQ organizes that the "earliest proposal presentation and consideration is 2026, and the earliest ratification (establishment of a new definition) is 2030," linked to the meeting cycle of the General Conference on Weights and Measures (CGPM).
Additionally, the roadmap page clearly states the "possibility of 2030," showing a stance of updating through a long process.


This is where it gets interesting. Even though technology is nearing "capability," the international standard won't move until the conditions for social implementation—continuous operation, mutual comparison, global deployment, legal systems, and stakeholder explanations—are met. In other words, the "redefinition of the second" is an update where science and technology collide head-on with social systems.


Measuring More Than Time: Reading Gravity Through "Clock Progression"

What makes optical atomic clocks interesting is that they are no longer just devices for time.


According to general relativity, the stronger the gravity, the slightly slower the time. Therefore, by comparing extremely precise clocks, the gravitational potential difference at each location can be measured as a "time lag." The article suggests that this property could help create an "international height standard not based on sea level."


In the world of geodesy and Earth observation, the alignment of altitudes and reference surfaces is a real challenge, and if we get closer to the level where "clocks can measure height," it could change the philosophy of maps and infrastructure management.


Also a Tool for Verifying "Fundamental Physics" Like Dark Matter

The article further states that optical atomic clocks can also be useful for verifying fundamental physics, such as dark matter.
By comparing multiple types of clocks, if there are phenomena where fundamental constants fluctuate slightly, they might appear as changes in frequency ratios. In other words, optical atomic clocks are becoming not just "time distribution devices" but also "instruments for exploring the universe."


Time as "Insurance" Against Satellite Failures

The accurate time we receive daily heavily depends on satellites (positioning). The article mentions that when satellite infrastructure is shaken by solar storms or malicious attacks, optical atomic clocks could serve as a "backup for time" on the ground.


This holds value as real risk management, not just a dream story from the laboratory.

The article also mentions commercialization efforts, touching on spin-out companies like QuantX Labs.
The sign that precision clocks are shifting from "symbols of national research" to "components of industry" might further accelerate their spread.


The Remaining Challenge: "Which Clock to Define the Second With"

No matter how excellent optical atomic clocks are, the "definition of a second" must be decided as one. The article raises the issue of whether to go with a "single optical atomic clock (single type, single transition)" or a "group (ensemble) of multiple methods" for redefinition, stating that direct comparison is necessary.


This issue is also organized in the FAQ of BIPM, with options such as "making a single transition a defined constant" and "making the weighted average of multiple optical transitions the definition."


A single method tends to simplify operations but increases dependency on that method. Multiple methods increase robustness but make agreement and operation more challenging. Whichever is chosen, it must be completed with a system that can distribute the "same second" worldwide.


Reactions on Social Media: Enthusiastic "Experts," Confused "General Public," and "Infrastructure Perspective" Resonates

The topic surrounding this article has divided reactions on social media across several layers.

1) Research and Measurement Community (LinkedIn)

On LinkedIn, research institution accounts are introducing that "optical atomic clocks will redefine the world's 'one second' in the near future," while discussing the importance of making them "usable in the field" through miniaturization and robustness. The message of moving from the laboratory to the real world is strong.
Similar posts also express that "clocks that are too precise turn time itself into a scientific tool," gathering expectations for applications in gravity and fundamental physics.

2) Engineering Community (Hacker News)

On Hacker News, questions leaning towards implementation and operation are prominent.
For example, questions like "Is it a 'clock' or a 'clock signal'?" arise, with technical explanations exchanged about how optical clocks find it difficult to emit continuous signals on their own, and how lasers, frequency combs, and redundancy (operating multiple units) are effective in generating real-time signals.
It's striking how the "difficulty of continuous operation," often omitted in articles for the general public, is at the forefront of the community's interest.

3) General Public (Overall Social Media Atmosphere)

Meanwhile, the general public's reactions are roughly divided into the following two types.

  • "Is such precision necessary in daily life?"

  • "But it seems important behind GPS, finance, and communication"


This temperature difference is natural. The better the clock, the less noticeable the difference in daily life. That's why "redefining the second" becomes news that carries both romance and practicality. For researchers, it's an event that changes the world, but for many, it easily becomes "So, what changes?"


However, what changes is not the display on your smartphone, but the underlying strength of society. In areas where "synchronization" is crucial, such as positioning, communication, power, finance, and scientific observation, the precision of time quietly makes an impact.


We Won't Notice the Day "Seconds Change," But the World Will Certainly Change

The "second" defined by cesium since 1967 has been the backbone of civilization for over half a century. Now, we are attempting to replace that backbone with light.


This is not merely an improvement of clocks. It is about rewriting the rules shared by the world and simultaneously acquiring the measurement capability to delve into the mysteries of gravity and the universe.


The next time the "second" is updated, our clocks will continue to run without a hitch. However, behind the scenes, humanity will have moved one step closer to being an entity that can "measure" nature.


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