The European Space Agency (ESA) will be launched on Monday, April 21 to the International Space Station (ISS) a set of atomic watches, to measure time with very high precision and prove the theory of relativity. The culmination of 30 years of work.
• What will be sent to space?
The Aces set, composed of two atomic watches, will be launched on Monday with a Falcon 9 rocket of Cap Canaveral Spacex (United States) to reach the International Space Station (ISS), at an altitude of 400 km.
The first watch, Pharao, will be a throbbing heart. Within an Ultravid tube, Cesium atoms will cool by laser at a temperature close to absolute zero (-273 ° C).
Immobilized by the cold and in a situation of impossible, its vibrations at a particular frequency will have more precision than on Earth.
• What is the objective of the mission?
Thanks to this mission, scientists will be able to “measure the effect of altitude on the flow of time”, summarizes with the France-Presse Didier Massonnet agency, head of the Pharao project at the National Center for French Space Studies (CNES).
We have known since 1915 and the theory of Albert Einstein’s general relativity that time is not the same everywhere. It slows down near a massive object, to the point of stopping at the edge of a black hole.
On Earth, time passes faster at the top of the Eiffel Tower than its base, but this “Einstein effect” is infinitesimal. On the other hand, it becomes noticeable when you go to space.
• Where do these atomic watches come from?
The unit of time, the second, has long been defined as a fraction of the Earth’s rotation: 1/86.4000 on an average solar day. But the earth does not rotate regularly. Unlike the “Tick-Tac” of atoms that emit regular electromagnetic radiation. What atomic watches, invented in the 1950s, manages to measure.
In 1967, the scientists defined the second as corresponding to 9,192,0631,770 oscillations of a Cesium 133 atom that changed the state of energy.
The 2000s saw the appearance of a new generation of watches, such optics, 100 times more precise than atomic watches. This should lead to a new definition of the second in the coming years.
• What relationship with relativity theory?
Together with another atomic clock, a furrow of hydrogen, the farao will give time with exceptional precision and stability. It will only derive from a second every 300 million years.
“Starting from an atomic clock concept, go to orbit, be able to maintain the standard of the second in the ISS and share it with atomic watches everywhere on Earth” turned out to be a “technologically very difficult and delicate project,” stressed during a Simon Weinberg press conference, British Aces Project Manager in that.
In the field, nine terminals worldwide (in Europe, Japan and the United States) will compare the time measured by Pharo with the time measured by their own watches. “The differences will be analyzed to determine if the result agrees with the predictions of the theory of relativity,” said Philippe Laurent, responsible for ACES/Pharao’s activities to the Paris Observatory, to the press.
• What possible consequences?
If the result does not agree with the theory of relativity, “a new window will open in the world of physics.” That will have to make adjustments to make Einstein’s equations coincide with the observations.
And perhaps progress in the search for the physicist’s grail: to reconcile the general relativity that explains the functioning of the universe and the quantum physics that governs the infinitely small. Two theories that work remarkably well. But so far it is incompatible.
Source: BFM TV
