PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

New principle may help explain why nature is quantum

2013-05-14
(Press-News.org) Like small children, scientists are always asking the question 'why?'. One question they've yet to answer is why nature picked quantum physics, in all its weird glory, as a sensible way to behave. Researchers Corsin Pfister and Stephanie Wehner at the Centre for Quantum Technologies at the National University of Singapore tackle this perennial question in a paper published 14 May in Nature Communications.

We know that things that follow quantum rules, such as atoms, electrons or the photons that make up light, are full of surprises. They can exist in more than one place at once, for instance, or exist in a shared state where the properties of two particles show what Einstein called "spooky action at a distance", no matter what their physical separation. Because such things have been confirmed in experiments, researchers are confident the theory is right. But it would still be easier to swallow if it could be shown that quantum physics itself sprang from intuitive underlying principles.

One way to approach this problem is to imagine all the theories one could possibly come up with to describe nature, and then work out what principles help to single out quantum physics. A good start is to assume that information follows

Einstein's special relativity and cannot travel faster than light. However, this alone isn't enough to define quantum physics as the only way nature might behave. Corsin and Stephanie think they have come across a new useful principle. "We have found a principle that is very good at ruling out other theories," says Corsin.

In short, the principle to be assumed is that if a measurement yields no information, then the system being measured has not been disturbed.

Quantum physicists accept that gaining information from quantum systems causes disturbance. Corsin and Stephanie suggest that in a sensible world the reverse should be true, too. If you learn nothing from measuring a system, then you can't have disturbed it.

Consider the famous Schrodinger's cat paradox, a thought experiment in which a cat in a box simultaneously exists in two states (this is known as a 'quantum superposition'). According to quantum theory it is possible that the cat is both dead and alive – until, that is, the cat's state of health is 'measured' by opening the box.

When the box is opened, allowing the health of the cat to be measured, the superposition collapses and the cat ends up definitively dead or alive. The measurement has disturbed the cat.

This is a property of quantum systems in general. Perform a measurement for which you can't know the outcome in advance, and the system changes to match the outcome you get. What happens if you look a second time? The researchers assume the system is not evolving in time or affected by any outside influence, which means the quantum state stays collapsed. You would then expect the second measurement to yield the same result as the first. After all, "If you look into the box and find a dead cat, you don't expect to look again later and find the cat has been resurrected," says Stephanie. "You could say we've formalised the principle of accepting the facts", says Stephanie.

Corsin and Stephanie show that this principle rules out various theories of nature. They note particularly that a class of theories they call 'discrete' are incompatible with the principle. These theories hold that quantum particles can take up only a finite number of states, rather than choose from an infinite, continuous range of possibilities. The possibility of such a discrete 'state space' has been linked to quantum gravitational theories proposing similar discreteness in spacetime, where the fabric of the universe is made up of tiny brick-like elements rather than being a smooth, continuous sheet.

As is often the case in research, Corsin and Stephanie reached this point having set out to solve an entirely different problem altogether. Corsin was trying to find a general way to describe the effects of measurements on states, a problem that he found impossible to solve. In an attempt to make progress, he wrote down features that a 'sensible' answer should have. This property of information gain versus disturbance was on the list. He then noticed that if he imposed the property as a principle, some theories would fail.

Corsin and Stephanie are keen to point out it's still not the whole answer to the big 'why' question: theories other than quantum physics, including classical physics, are compatible with the principle. But as researchers compile lists of principles that each rule out some theories to reach a set that singles out quantum physics, the principle of information gain versus disturbance seems like a good one to include.



INFORMATION:

Reference:

"An information-theoretic principle implies that any discrete physical theory is classical", Nature Communications, doi: 10.1038/ncomms2821 (2013) Preprint available at http://arxiv.org/abs/1210.0194

About the researchers:

Stephanie Wehner is a Principal Investigator at the Centre for Quantum Technologies and Assistant Professor at the National University of Singapore.
wehner@comp.nus.edu.sg
+65 6601 1478

Corsin Pfister is a PhD Student at the Centre for Quantum Technologies in Stephanie's group.
corsin@nus.edu.sg
+65 6601 2648



ELSE PRESS RELEASES FROM THIS DATE:

Making gold green: New non-toxic method for mining gold

2013-05-14
Northwestern University scientists have struck gold in the laboratory. They have discovered an inexpensive and environmentally benign method that uses simple cornstarch -- instead of cyanide -- to isolate gold from raw materials in a selective manner. This green method extracts gold from crude sources and leaves behind other metals that are often found mixed together with the crude gold. The new process also can be used to extract gold from consumer electronic waste. Current methods for gold recovery involve the use of highly poisonous cyanides, often leading to contamination ...

Rotavirus vaccine developed in India demonstrates strong efficacy

2013-05-14
New Delhi, India—The Government of India's Department of Biotechnology (DBT) and Bharat Biotech announced positive results from a Phase III clinical trial of a rotavirus vaccine developed and manufactured in India. Data from the trial, presented today at the International Symposium on Rotavirus Vaccines for India—The Evidence and the Promise, showed ROTAVAC® to have an excellent safety and efficacy profile. The clinical study demonstrates for the first time that the India-developed rotavirus vaccine ROTAVAC® is efficacious in preventing severe rotavirus diarrhoea in ...

Cognitive training improves executive function in breast cancer survivors

2013-05-14
Women whose breast cancer had been treated with chemotherapy demonstrated improved executive function, such as cognitive flexibility, verbal fluency and processing speed after using exercises developed by Lumosity, the leading online cognitive training program. The study also found significant improvement in self-reported measures of everyday executive function and observed some transfer to verbal memory. Researchers at Stanford University published the results in the peer-reviewed journal, Clinical Breast Cancer. Dr. Shelli Kesler, Assistant Professor of Psychiatry and ...

Flower power fights orchard pests

2013-05-14
WENATCHEE, Wash. – Washington State University researchers have found they can control one of fruit growers' more severe pests, aphids, with a remarkably benign tool: flowers. The discovery is a boon for organic as well as conventional tree fruit growers. The researchers recently published their study in the journal Biological Control. They found that plantings of sweet alyssum attracted a host of spiders and predator bugs that in turn preyed on woolly apple aphids, a pest that growers often control with chemical sprays. "The results were striking," said Lessando Gontijo, ...

Playing at pirate games

2013-05-14
The results of a large-scale, analysis of BitTorrent file-sharing of computer games, focusing on using open methodologies are to be published in the International Journal of Advanced Media and Communication and bust some of the common myths about digital piracy. The controversy about illegal file sharing over the Internet has been a focus of intense attention from industry and media alike for the past decade. Despite the massive financial interests involved, there is, however, only limited factual knowledge available backing claims from either side of the controversy. Focusing ...

Do potatoes grow on vines? A review of the wild relatives of some favorite food plants

2013-05-14
The Solanaceae, also called the potato or nightshade family, includes a wide range of flowering plants, some of which are important agricultural crops. Tomatoes, potatoes, aubergines, peppers and wolfberries are all representatives of the family present on many tables across the world. Solanum is the largest genus of the family, and with 1500 species, is one of the largest genera of flowering plants. Solanum has 13 major evolutionary groups,or clades. This new study published in the open access journal Phytokeys offers a complete revision of all of the species of the Dulcamaroid ...

IT industry ignores silver surfers at its peril

2013-05-14
Hardware and software vendors are foolish to ignore the needs of the growing population of older computer and information technology users, the so-called "silver surfers". US researchers offer convincing evidence in a monograph to be published in the International Journal of Intercultural Information Management that from the business perspective, seniors represent a rapidly growing sector of the market with the most disposable income to spend on these companies' products. Mark McMurtrey, Ronald McGaughey, James Downey and Steven Zeltmann of the Department of Management ...

Fish oil may stall effects of junk food on brain

2013-05-14
Data from more than 180 research papers suggests fish oils could minimise the effects that junk food can have on the brain, a review by researchers at the University of Liverpool has shown. The team at the University's Institute of Ageing and Chronic Disease reviewed research from around the world to see whether there was sufficient data available to suggest that omega-3s had a role to play in aiding weight loss. Research over the past 10 years has indicated that high-fat diets could disrupt neurogenesis, a process that generates new nerve cells, but diets rich in omega-3s ...

Sulfate aerosols cool climate less than assumed

2013-05-14
This news release is available in German. In their role as condensation nuclei, aerosol particles are an important trigger for the formation of clouds. As humidity accumulates on the particles droplets are formed, which later develop into clouds. Within the clouds, however, the chemical composition of these aerosol particles changes. In order to find out exactly what happens within the clouds, Eliza Harris and Bärbel Sinha from the Max Planck Institute for Chemistry, together with other scientists form Mainz and further research institutes, investigated different ...

But what does it do?

2013-05-14
Although we know the tool's general purpose, it can sometimes be difficult to tell if a specific pair of precision tweezers belongs to a surgeon or a master jeweller. It is now easier to solve similar conundrums about a type of protein that allows cells to react to their environment, thanks to scientists at the European Molecular Biology Laboratory (EMBL). Published today in Science Signaling, their work offers a valuable resource for other researchers. Whether in your eye being hit by light, in your blood fighting off disease, or elsewhere throughout your body, cells ...

LAST 30 PRESS RELEASES:

Danforth Plant Science Center adds two new faculty members

Robotic eyes mimic human vision for superfast response to extreme lighting

Racial inequities and access to COVID-19 treatment

Residential segregation and lung cancer risk in African American adults

Scientists wipe out aggressive brain cancer tumors by targeting cellular ‘motors’

Capturability distinction analysis of continuous and pulsed guidance laws

CHEST expands Bridging Specialties Initiative to include NTM disease and bronchiectasis on World Bronchiectasis Day

Exposure to air pollution may cause heart damage

SwRI, UTSA selected by NASA to test electrolyzer technology aboard parabolic flight

Prebiotics might be a factor in preventing or treating issues caused by low brain GABA

Youngest in class at higher risk of mental health problems

American Heart Association announces new volunteer leaders for 2025-26

Gut microbiota analysis can help catch gestational diabetes

FAU’s Paulina DeVito awarded prestigious NSF Graduate Research Fellowship

Champions for change – Paid time off initiative just made clinical trials participation easier

Fentanyl detection through packaging

Prof. Eran Meshorer elected to EMBO for pioneering work in epigenetics

New 3D glacier visualizations provide insights into a hotter Earth

Creativity across disciplines

Consequences of low Antarctic sea ice

Hear here: How loudness and acoustic cues help us judge where a speaker is facing

A unique method of rare-earth recycling can strengthen the raw material independence of Europe and America

Epilepsy self-management program shows promise to control seizures, improve mood and quality of life

Fat may play an important role in brain metabolism

New study finds no lasting impact of pandemic pet ownership on human well-being

New insights on genetic damage of some chemotherapies could guide future treatments with less harmful side effects

Gut microbes could protect us from toxic ‘forever chemicals’

Novel modelling links sea ice loss to Antarctic ice shelf calving events

Scientists can tell how fast you're aging from a single brain scan

U.S. uterine cancer incidence and mortality rates expected to significantly increase by 2050

[Press-News.org] New principle may help explain why nature is quantum