![How world's most precise clock could transform fundamental physics](https://www.portugalcolonial.pt/media/shared/articles/c0/a2/f9/How-world-s-most-precise-clock-coul-052447.jpg)
-
'Windmill love' sees Dutch artist become mill operator
-
US defends law forcing sale of TikTok app
-
Messi out for defending champ Miami as Leagues Cup begins
-
Australia bans uranium mining at Indigenous site
-
Divers attempt to reach sunken Philippine oil tanker
-
Trump accuses Harris of anti-Semitism in overblown speech
-
Coughlin clings to lead at LPGA Canadian Women's Open
-
Trump offers tech sector policy flips ahead of election
-
Spacecraft to swing by Earth, Moon on path to Jupiter
-
What's the fallout of Mexican drug lords' capture?
-
Video game makers see actors as AI 'data,' says union on strike
-
Chinese qualifier Shang to face Thompson in ATP Atlanta semis
-
'Massive attack' on French rail threatens more chaos
-
'We did it!': France breathes sigh of relief after Olympics ceremony
-
Regional concern grows as Venezuela blocks vote observers
-
Historic river parade, Dion show-stopper ignite Paris Olympics
-
Rainy Paris Olympic parade dampens many spectators' spirits
-
The one of a kind Paris opening ceremony: five memorable moments
-
Justin Timberlake seeks to dismiss DUI case
-
Warner Brothers Discovery sues NBA over Amazon rights deal
-
Kobe Bryant locker, Maradona jersey up for auction in New York
-
Historic river parade launches Paris Olympics
-
New York family of Holocaust victim reclaims Nazi-looted art
-
NASA Mars rover captures rock that could hold fossilized microbes
-
Thousands evacuate season's biggest wildfire in northern California
-
Ethiopia mourns victims of landslide tragedy
-
Lady Gaga adds sparkle to star-studded Olympic show
-
Airbus and Boeing supremacy secure despite turbulence
-
Teams sail down Seine in rain-soaked Olympics opening ceremony
-
West Indies' treble strike rocks England in third Test
-
Olympic opening ceremony under way on River Seine
-
Mott's England future uncertain as ECB chief fails to offer support
-
Trump meets Israeli PM Netanyahu in Florida
-
S.African police say 95 Libyans detained at suspected military camp
-
Blinken set for talks with Chinese counterpart in Laos
-
Norris heads Piastri in McLaren one-two at Belgian GP practice
-
G20 seeks common ground on taxing super-rich
-
European medicines watchdog rejects new Alzheimer's drug
-
Habib, Ebden eye Alcaraz and Djokovic shocks at Olympics tennis
-
Long queues, ticketing problems ahead of Paris opening ceremony
-
Two Sinaloa Cartel leaders face US charges after stunning capture
-
Spain train driver jailed for 2.5 years over deadly 2013 crash
-
Paris poised for Olympic opening ceremony spectacular
-
Judoka fails doping test in first case at Paris Olympics
-
Holder and Da Silva keep England at bay after West Indies collapse
-
Alpine F1 boss Bruno Famin to leave in August
-
Ethiopia declares three days of mourning after landslide tragedy
-
Brazilian dunes dotted with dazzling pools make UNESCO heritage list
-
Rain, cooling slow huge blaze in Canada's Jasper park
-
French Rugby's Jaminet suspended 34 weeks after racist video: Federation
![How world's most precise clock could transform fundamental physics](https://www.portugalcolonial.pt/media/shared/articles/c0/a2/f9/How-world-s-most-precise-clock-coul-052447.jpg)
How world's most precise clock could transform fundamental physics
US scientists have measured Albert Einstein's theory of general relativity -- which holds that gravity slows time down -- at the smallest scale ever, demonstrating that clocks tick at different rates when separated by fractions of a millimeter.
Jun Ye, of the National Institute of Standards and Technology (NIST) and the University of Colorado Boulder, told AFP it was "by far" the most precise clock ever built -- and could pave the way for new discoveries in quantum mechanics, the rulebook for the subatomic world.
Ye and colleagues published their findings in the prestigious journal Nature on Wednesday, describing the engineering advances that enabled them to build a device 50 times more precise than their previous best clock, itself a record-breaker, built in 2010.
It was more than a century ago, in 1915, that Einstein put forward his theory of general relativity, which held that the gravitational field of a massive object distorts space-time.
This causes time to move more slowly as one approaches closer to the object.
But it wasn't until the invention of atomic clocks -- which keep time by detecting the transition between two energy states inside an atom exposed to a particular frequency -- that scientists could prove the theory.
Early experiments included the Gravity Probe A of 1976, which involved a spacecraft six thousand miles (10,000 kilometers) above Earth's surface and showed that an onboard clock was faster than an equivalent on Earth by one second every 73 years.
Since then, clocks have become more and more precise, and thus better able to detect the effects of relativity.
A decade ago, Ye's team set a record by observing time moving at different rates when their clock was moved 33 centimeters (just over a foot) higher.
- Theory of everything -
Ye's key breakthrough was working with webs of light, known as optical lattices, to trap atoms in orderly arrangements. This is to stop the atoms from falling due to gravity or otherwise moving, resulting in a loss of accuracy.
Inside Ye’s new clock are 100,000 strontium atoms, layered on top of each other like a stack of pancakes, in total about a millimeter high.
The clock is so precise that when the scientists divided the stack into two, they could detect differences in time in the top and bottom halves.
At this level of accuracy, clocks essentially act as sensors.
"Space and time are connected," said Ye. "And with time measurement so precise, you can actually see how space is changing in real time -- Earth is a lively, living body."
Such clocks spread out over a volcanically-active region could tell geologists the difference between solid rock and lava, helping predict eruptions.
Or, for example, study how global warming is causing glaciers to melt and oceans to rise.
What excites Ye most, however, is how future clocks could usher in a completely new realm of physics.
The current clock can detect time differences across 200 microns -- but if that was brought down to 20 microns, it could start to probe the quantum world, helping bridge gaps in theory.
While relativity beautifully explains how large objects like planets and galaxies behave, it is famously incompatible with quantum mechanics, which deals with the very small, and holds that everything can behave like a particle and a wave.
The intersection of the two fields would bring physics a step closer to a unifying "theory of everything" that explains all physical phenomena of the cosmos.
F.Ferraz--PC