Microscope: the small satellite that would revolutionize physics – The Point

It is called Microscope and, as its name does not indicate, it is a satellite. A small satellite to 90% French, of just 300 kilos, which aims to bring physics into a new era. How? Going check – hoping to disprove it – a feather and a hammer fall, in vacuum, in the same way. The assertion of the laws of physics since Galileo and Newton, and so-called universality of free fall of bodies in space, under the effect of gravity. A cornerstone of the theory of Einstein’s general relativity, ie physics today, became like a stone in the shoe of the physics of tomorrow …

to create a gap possibility of a bridge

Why? Because the principle of equivalence prevents build bridges between the two main theories of physics, namely general relativity, which describes the infinitely large, and quantum mechanics, which describes the very small. Indeed, as explained by the head of the microscope project CNES, Yves André, unifying theories exist, “but they need to be introduced as a violation of the universality of the fall in order to go beyond.” “So Professor Thibault Damour, a member of the Academy of Sciences, one of the instigators of the Microscope project, he proposes a theory providing a violation (note: that is to say a difference in behavior between two body falling in a vacuum) beyond the fourth decimal place. “But until now, the universality of the fall could be verified until the thirteenth decimal only …

So if Microscope to be launched this Friday for a set orbit around the earth at 707 km altitude, is to try to make at least 100 times better. The ambition is indeed to make an accurate measurement up to the fifth decimal place, hoping to find a small difference in kind to show that general relativity is not complete, but that can link it to something else. As if you were installing a hitch ball on your car so you can hang a caravan. “To take the example of the theory proposed by Professor Thibault Damour, it needs to introduce a violation of the equivalence principle at the Fourteenth decimal” says Yves André.

Cylinders in a lab freefall

to achieve this degree of precision, the Microscope satellite was built as a small laboratory. “His tools, unlike most other satellites, are therefore, not outside, but inside,” says Yves André. In reality, Microscope essentially contains two identical tools each with a set of two cylinders, one within the other so as to have almost the same center of gravity. In the first, intended to measure the long-awaited, these two cylinders are made of two different materials, one in titanium, in the role of the pen, the other platinum-rhodium, in the role of the hammer. In the second, however, the two cylinders are platinum to be a witness.

So how do you simulate their fall? “Inside the two differential accelerometers, cylinders remain fixed, or more exactly will be maintained so as to remain fixed by electrostatic forces, while the satellite him, orbiting the Earth, will be already almost in free fall in a vacuum, “says Yves André. At this altitude, there are of course always a little air, but, to compensate for its effects on the satellite’s behavior, very precise micro-drives were planned. “Microscope was designed to remove all parasites forces that distort the measurement, to the tiny pressure as photons of sunlight acting on the satellite, said the project manager. What we measure is the force required to maintain each cylinder to compare if it is absolutely identical. “If they are identical, the principle of universality of falling bodies in a vacuum will remain true until a new attempt to prove otherwise, and will continue to annoy physicists. Conversely, if a small difference is found, it will open the way to unification theories of physics and will begin to make a first selection in the proposals already developed before possibly invent others.

Meanwhile, the launch of the small but ambitious Microscope is scheduled April 22 at 23 pm 2 (Paris time) from Kourou, French Guiana, news is expected on Earth around 4 pm Saturday morning. From then until September a series of tests will be performed before entering the heart of the action in October if all goes well … “This operational exploitation phase should last eighteen months after what we will decide on a possible extension of the mission, “said Yves André. As for the long-awaited measure, it will probably not be revealed until at least two years.