Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. 24/7 Space News .




TIME AND SPACE
Researchers say distant quasars could close a loophole in quantum mechanics
by Jennifer Chu, MIT News Office
Boston MA (SPX) Feb 26, 2014


Artist's interpretation of ULAS J1120+0641, a very distant quasar. Image courtesy ESO/M. Kornmesser.

In a paper published this week in the journal Physical Review Letters, MIT researchers propose an experiment that may close the last major loophole of Bell's inequality - a 50-year-old theorem that, if violated by experiments, would mean that our universe is based not on the textbook laws of classical physics, but on the less-tangible probabilities of quantum mechanics.

Such a quantum view would allow for seemingly counterintuitive phenomena such as entanglement, in which the measurement of one particle instantly affects another, even if those entangled particles are at opposite ends of the universe. Among other things, entanglement - a quantum feature Albert Einstein skeptically referred to as "spooky action at a distance"- seems to suggest that entangled particles can affect each other instantly, faster than the speed of light.

In 1964, physicist John Bell took on this seeming disparity between classical physics and quantum mechanics, stating that if the universe is based on classical physics, the measurement of one entangled particle should not affect the measurement of the other - a theory, known as locality, in which there is a limit to how correlated two particles can be. Bell devised a mathematical formula for locality, and presented scenarios that violated this formula, instead following predictions of quantum mechanics.

Since then, physicists have tested Bell's theorem by measuring the properties of entangled quantum particles in the laboratory. Essentially all of these experiments have shown that such particles are correlated more strongly than would be expected under the laws of classical physics - findings that support quantum mechanics.

However, scientists have also identified several major loopholes in Bell's theorem. These suggest that while the outcomes of such experiments may appear to support the predictions of quantum mechanics, they may actually reflect unknown "hidden variables" that give the illusion of a quantum outcome, but can still be explained in classical terms.

Though two major loopholes have since been closed, a third remains; physicists refer to it as "setting independence," or more provocatively, "free will."

This loophole proposes that a particle detector's settings may "conspire" with events in the shared causal past of the detectors themselves to determine which properties of the particle to measure - a scenario that, however far-fetched, implies that a physicist running the experiment does not have complete free will in choosing each detector's setting. Such a scenario would result in biased measurements, suggesting that two particles are correlated more than they actually are, and giving more weight to quantum mechanics than classical physics.

"It sounds creepy, but people realized that's a logical possibility that hasn't been closed yet," says MIT's David Kaiser, the Germeshausen Professor of the History of Science and senior lecturer in the Department of Physics. "Before we make the leap to say the equations of quantum theory tell us the world is inescapably crazy and bizarre, have we closed every conceivable logical loophole, even if they may not seem plausible in the world we know today?"

Now Kaiser, along with MIT postdoc Andrew Friedman and Jason Gallicchio of the University of Chicago, have proposed an experiment to close this third loophole by determining a particle detector's settings using some of the oldest light in the universe: distant quasars, or galactic nuclei, which formed billions of years ago.

The idea, essentially, is that if two quasars on opposite sides of the sky are sufficiently distant from each other, they would have been out of causal contact since the Big Bang some 14 billion years ago, with no possible means of any third party communicating with both of them since the beginning of the universe - an ideal scenario for determining each particle detector's settings.

As Kaiser explains it, an experiment would go something like this: A laboratory setup would consist of a particle generator, such as a radioactive atom that spits out pairs of entangled particles. One detector measures a property of particle A, while another detector does the same for particle B.

A split second after the particles are generated, but just before the detectors are set, scientists would use telescopic observations of distant quasars to determine which properties each detector will measure of a respective particle. In other words, quasar A determines the settings to detect particle A, and quasar B sets the detector for particle B.

The researchers reason that since each detector's setting is determined by sources that have had no communication or shared history since the beginning of the universe, it would be virtually impossible for these detectors to "conspire" with anything in their shared past to give a biased measurement; the experimental setup could therefore close the "free will" loophole.

If, after multiple measurements with this experimental setup, scientists found that the measurements of the particles were correlated more than predicted by the laws of classical physics, Kaiser says, then the universe as we see it must be based instead on quantum mechanics.

"I think it's fair to say this [loophole] is the final frontier, logically speaking, that stands between this enormously impressive accumulated experimental evidence and the interpretation of that evidence saying the world is governed by quantum mechanics," Kaiser says.

Now that the researchers have put forth an experimental approach, they hope that others will perform actual experiments, using observations of distant quasars.

"At first, we didn't know if our setup would require constellations of futuristic space satellites, or 1,000-meter telescopes on the dark side of the moon," Friedman says. "So we were naturally delighted when we discovered, much to our surprise, that our experiment was both feasible in the real world with present technology, and interesting enough to our experimentalist collaborators who actually want to make it happen in the next few years."

Adds Kaiser, "We've said, 'Let's go for broke - let's use the history of the cosmos since the Big Bang, darn it.' And it is very exciting that it's actually feasible."

.


Related Links
Massachusetts Institute of Technology
Understanding Time and Space






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





UAV Payloads 2014, 24 - 25 June - London, UK
TIME AND SPACE
Optimising custody is child's play for physicists
Heidelberg, Germany (SPX) Feb 26, 2014
Physics can provide insights into societal trends. Problems involving interactions between people linked in real-life networks can be better understood by using physical models. As a diversion from his normal duties as a theoretical physicist, Andres Gomberoff from the Andres Bello University in Santiago, Chile, set out to resolve one of his real-life problems: finding a suitable weekend f ... read more


TIME AND SPACE
China Focus: Uneasy rest begins for China's troubled Yutu rover

Is Yutu Stuck?

Japan's Pocari Sweat bound for the moon: maker

Lunar ownership laws: a future necessity?

TIME AND SPACE
NASA Mars Orbiter Views Opportunity Rover on Ridge

Curiosity Adds Reverse Driving for Wheel Protection

Curiosity Drives On After Crossing Martian Dune

The World Above and Beyond

TIME AND SPACE
DARPA Open Catalog Makes Agency-Sponsored Software and Publications Available to All

Orion Underway Recovery Testing Begins off the Coast of California

Inside astronaut Alexander's head

NASA Welcomes University Participants to Develop Science Payloads

TIME AND SPACE
No Call for Yutu

What's up, Yutu

China's Jade Rabbit rover comes 'back to life'

Yutu Awakes

TIME AND SPACE
Space suit leak happened before, NASA admits

NASA Seeks US Industry Feedback on Options for Future ISS Cargo Services

NASA, International Space Station Partners Announce Future Crew Members

Andrews Space Cargo Module Power Unit Provides Power For Payloads Bound For ISS

TIME AND SPACE
'Mission of Firsts' Showcased New Range-Safety Technology at NASA Wallops

First Copernicus satellite at launch site

Arianespace to launch OPTSAT 3000 and VENuS satellites

Lighter engines a headache for satellite launcher Ariane

TIME AND SPACE
NASA cries planetary 'bonanza' with 715 new worlds

Detection of Water Vapor in the Atmosphere of a Hot Jupiter

ESA selects planet-hunting PLATO mission

Rife with hype, exoplanet study needs patience and refinement

TIME AND SPACE
EIAST showcases DubaiSat-2 results, plans for KhalifaSat at space conference in Singapore

A New Way to Create Porous Materials

USAF reveals 'neighborhood watch' satellite program

UT Dallas-led team makes powerful muscles from fishing line and sewing thread




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.