Two photons in free space do not interact. Light waves can pass through each other without having any influence on each other at all. For many applications in quantum technology, however, interaction between photons is crucial. It is an indispensable prerequisite for transmitting information through tap-proof quantum channels or for building optical logic gates. At the Vienna University of Technology (TU Wien), scientists have now succeeded in establishing a strong interaction between two single photons. This opens up completely new possibilities for quantum optics. The experimental results have now been published in the journal "Nature Photonics".

Interaction Usually Requires Bright Light

The microbes living in people's guts are much less diverse than those in humans' closest relatives, the African apes. What does that mean? No one knows, but the microbiome is all the latest rage in marketing, with probiotics advertised on television and a segment of the research community rushing to create studies to capitalize on that.

Abortion has been federal law in America for over 40 years, yet every election cycle politicians in Democratic Congressional districts campaign on the issue - and sociologists write about this common medical procedure. How common? So common it happens more often than miscarriages, according to a new paper.

Surveys are not telling us much new at this point but a sociologist writing in Sociological Science analyzes a survey and finds that anti-abortion people are less likely to hear about the abortions women they know have had than are pro-abortion Americans.

Over 200,000 United States troops who fought in the 1990-1991 campaign to liberate Kuwait from Iraqi invaders have been diagnosed with a set of chronic health problems dubbed Gulf War Syndrome. The symptoms range from fatigue, muscle pain and weakness to decreased cognitive function and gastrointestinal and skin problems, even decades after the conflict. 

What are the most important discussions to have among doctors, patients and families?

It seems obvious to just ask but there is a gap between what patients would like and the care they actually receive, according to a paper in the Canadian Medical Association Journal.

Current guidelines list 11 key elements for health care providers to discuss regarding end-of-life care, although these are based mainly on expert opinion and not on patient and family feedback.

String theory is a hypothetical framework where particle physics is replaced by one-dimensional objects called strings. It was originally proposed as a way to explain the strong force, then advocates re-purposed it for quantum gravity, and now it is being reconfigured again, with "commutation rules" of quantum mechanics.

The heart of what became string theory began in the early 20th century and then got jumbled in with a lot of philosophical ideas - 'what if there are dimensions we can't see?' A fifth dimension was a nice discussion, but without being detected it was just that. As the century moved on, Kaluza-Klein theory, S-matrix theory, everyone kept coming up with new stuff and it all eventually became what we now know as String Theory.