Thursday , June 24 2021

These atomic clocks are so precise that they can measure the distortion of space-time – Science News



These watches are so accurate that they would lose only half a second if the universe had lasted. That's 14 billion years.

key points

Key points:

  • The most accurate watches in the world are atomic clocks, which use lasers and electrons to adjust the speed of "ticking"
  • A new pair of ultra-precise atomic clocks based on the ytterbium element have record stability and synchronization
  • By measuring the distortion of space and time, atomic such as these can help to explore the interior of the Earth and discover the dark matter

But it will not be used to maintain trains in time. Exquisite clarity of watches, described today in Nature, means that they can measure how space-time distorts under gravitational forces.

Finally, astrophysicists could find help in detecting mysterious dark matter.

Even now, the clocks could tell us what's going on inside the country by accurately mapping the impacts and clutches of our planet-if the clocks are reduced, that is.

Co-author Will McGrew, PhD student at the National Institute of Standards and Technology in the United States, said that the "ticking" of the timers was generated by oscillation of radiation emitted when the electrons in the ytterbium atom were excited by lasers.

It turns out that they printed, in a nearly perfect spirit, 500 trillion times a second.

"Measurement of time and frequency with such incredible precision provides a truly powerful juice to see the natural world," McGrew said.

Atomic time 101

Time measurement is based on astronomy. For example, the length of the day is determined by one spin of the Earth on its axis.

But astronomical phenomena tend to slow down or accelerate.

Our days are extended, an additional 1.7 milliseconds each century, thanks to our gravitational tango with the moon.

So while astronomical weather could be done for a timetable and so, science requires precision.

And here the atomic weather shines.

Instead of looking at the sky, this form of holding exercise in radiation waves discards atoms when they are bathed in laser light.

what are the atomic clocks of & # 39;?

What atomic watches "signify"?

  • The other is defined by the motion of the electron in the cesium-133 atom containing a nucleus – contains 55 proton and 78 neutrons – surrounded by 55 electrons
  • As electrons hear around the nucleus, they occupy different orbits or "energy levels"
  • Electrons can "jump" between levels when they absorb or release a certain amount of energy
  • The energy emitted every time the electron makes a certain jump is always the same, and in the form of microwaves
  • These microwave networks have a certain frequency (number of full waves completed every second), which can be measured as the rate of "ticking" atoms
  • Cesium-133 "patch" 9,192,631,770 times every second

They sound super futuristic, but atomic clocks have been for more than 60 years.

The first atomic clock that was precise enough to be used for time setting was built in 1955 at the British National Physical Laboratory.

It was true for a second for 300 years.

Some 12 years later, the atomic clock of cesium became an international time standard, and over time, atomic clocks became more accurate.

Modern atomic clocks using strontium or ytterbium instead of cesium have lost one second for every 300 million years or so.

More than time guards

The accuracy of atomic clocks means that they tested the general theory of relativity of Albert Einstein, which predicted that time passes faster or slower under the influence of different gravitational forces.

In other words, the clock placed on a satellite that circles the Earth, which has a higher "potential of gravity", will indicate more than an hour at sea level.

And there are already atomic clocks that span the earth across satellites that exploit this effect of dilation.

They would not have a global positioning system or GPS, without them.

Another use of satellite-mounted atomic clocks is to accurately map the Earth's size, shape, orientation in space, and mass distribution, collectively called "geodesy".

Satellite geodesy usually means how long the light should travel between distant points, such as laser glare to satellite, and how long it takes to return to the receiver on Earth.

GPS geodesy is accurate to about a centimeter, said Matt King, who uses satellite geodesy at the University of Tasmania and was not included in the studio.

However, watches with higher speeds "tick" – that is, higher frequency – should not use light at all. They could use the relativistic effects of gravity.

That's what Mr. McGrew and his colleagues wanted to achieve their atomic clock.

Instead of cesium, they used yterbium. Radiation radiation emitted by yttterium atoms oscillates almost five orders of magnitude faster than those from the cesium atom.

In his article, the team showed that watches are extremely stable – losing or getting time virtually imperceptible – making them almost perfect in bite.

Thus, by comparing the ticking difference between the two ytterbium clocks set on separate continents, a person can reasonably measure the height difference between the hours and below the centimeter.

Using the precision of ultra-sensitive atomic clocks would be like "watching the telescope inside," said Professor King.

"Let's say you have an earthquake," he said.

"If you can accurately measure this, you can find out the basics of the interior of the earth, such as its viscosity or permeability."

As the Earth rises back when the glaciers dissolve or sink when groundwater is pumped, they can also be tracked by atomic clocks.

Seeing how the earth around the volcano raises and descends, even on the centimeter scale, can tell volcanologists how the magma moves down, Professor King added.

"Combine it with seismology and get a real picture of what's going on inside."

Great applications, compact clock

So what prevents atomic clocks from excursions to volcanic and earthquake-prone areas around the world?

Simply, ytterbium watches are great for movement.

"[The clocks] basically they take a fairly large lab, "said McGrew.

This is because they need a bunch of large lasers to work.

Several lasers cool the attributes of ytterbium in diameter above absolute zero (-273 degrees Celsius) while others hold cooled atoms in place.

Mr. McGrew and his colleagues have already begun work on reducing the system.

Professor King is optimistic that ultra-precision atomic clocks will be compact enough one day to be able to be used both on Earth and in space.

"Computers were also used full of rooms.

"We could be 20 years old, maybe it will be earlier, but if this is [ytterbium clocks] can be miniaturized and if precision continues to increase, then there is no lack of application. "

Strange and wonderful

Below the line, atomic clocks could be used for experiments involving the measurement of the smallest distortions in space-time, such as the incredible subtle stretching and suppression of matter caused by a gravitational wave.

For example, take dark matter. Astrophysicists know that dark matter is there and that makes up about a quarter of the total mass and energy in the universe.

But his "dark" nature – that he does not seem to reflect, absorb or emit radiation – means it's very difficult to detect.

One dark-matter model suggests that it can interact with ordinary matter by changing the basic constants of nature, McGrew said.

And this is where atomic clocks can help an astrophysicist learn a bit about unusual things.

"Let's say there is a large object of dark matter passing through a laboratory that has an ytterbium watch and a strontium watch," said McGrew.

"[The dark matter] it would affect ytterbium by some factors, and then on strontium by some other factor.

"By measuring the difference between two hours you can detect the presence of a dark matter object.

"These are extremely subtle effects, but when you can make measurements with 18 digits of accuracy, you could discover them."

And, of course, there are purposes that we have not yet dreamed of.

"The people who first made atomic clocks did not know how to build a GPS device," said McGrew.

"I think it's something similar to say about atomic watches – that their most important, most important applications have not yet been considered."

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