Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Gravity leaps into quantum world

17.01.2002


Particles don’t fall smoothly under gravity, they lurch.
© Pictor/Photodisc


Researchers finally measure the subtle quantum effects of fourth fundamental force.

Far from falling smoothly, objects moving under gravity do so in lurching, quantum leaps, a French experiment has revealed1. The finding confirms that gravity, like the Universe’s three other fundamental forces, can have a quantum effect.

Particles, such as electrons confined to their orbital shells around the nucleus of an atom, are restricted by the rules of quantum mechanics. To move from one position to another, they must jump to the next quantum state.



Theoretically, this rule holds for all matter under the influence of nature’s four fundamental forces: electromagnetism, weak and strong nuclear force and gravity. But gravity, especially at small scales, is a very feeble force, making it extremely difficult to measure its quantum effects.

There’s no point in looking for quantum behaviour in everyday objects. It is occurring, but the larger things become, the more subtle are the quantum effects. Even small molecules are practically immune to the weird ways of the quantum world.

Valery Nesvizhevsky and his colleagues studied ultracold neutrons (UCNs) at the Laue-Langevin Institute in Grenoble, France. These very slow-moving, uncharged particles normally team up with protons to form the nucleus of an atom. The team isolated the neutrons from the effects of the other three forces in a specially designed detector.

By following the progress of hundreds of UCNs falling from the top of the detector to the bottom, the team found that the particles exist only at certain heights. "They do not move continuously, but rather jump from one height to another as quantum theory predicts," says Nesvizhevsky.

That someone has measured quantum leaps has physicists wide-eyed. "The effects are so small it is remarkable that they can actually observe them," says Thomas Bowles, a particle physicist at Los Alamos National Laboratory in New Mexico.

Trick questions

This satisfying trick may also have profound implications for the future of physics. "Right now, we don’t have a theory of how gravity is created," says Bowles. If refined, he says, apparatus like Nesvizhevsky’s could explain how gravity behaves in the quantum world - and perhaps where it comes from.

"If you’re searching for something in fundamental physics, this is a very clean system," agrees Nesvizhevsky. It should allow researchers to pick apart some of the niggling questions about the fundamental properties of matter.

It might even be possible, suggests Bowles, to work out why Einstein’s theory of general relativity - which explains gravity and large things, such as galaxies and the Universe - doesn’t tally with quantum mechanics, the physicist’s handbook of the very small.

References

  1. Nesvizhevsky, V. V. et al. Quantum states of neutrons in the Earth’s gravitational field. Nature, 415, 297 - 299, (2002).


TOM CLARKE | © Nature News Service
Further information:
http://www.nature.com/nsu/020114/020114-8.html

More articles from Physics and Astronomy:

nachricht Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology

nachricht NASA team finds noxious ice cloud on saturn's moon titan
19.10.2017 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Electrode materials from the microwave oven

19.10.2017 | Materials Sciences

New material for digital memories of the future

19.10.2017 | Materials Sciences

Physics boosts artificial intelligence methods

19.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>