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 Hope to discover sure signs of life on Mars? New research says look for the element vanadium
22.09.2017 | University of Kansas

nachricht Calculating quietness
22.09.2017 | Forschungszentrum MATHEON ECMath

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: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>