In 1915 Albert Einstein formulated the theory of general relativity which fundamentally changed our understanding of gravity. He explained gravity as the manifestation of the curvature of space and time. Einstein's theory predicts that the flow of time is altered by mass.

This effect, known as "gravitational time dilation", causes time to be slowed down near a massive object. It affects everything and everybody; in fact, people working on the ground floor will age slower than their colleagues a floor above, by about 10 nanoseconds in one year.

Now that Philae has woken up, we may be on the brink of major steps forward in our understanding of comets. We already know that perhaps as much as 30% of a comet consists of dust and organics. Now we'll be able to look at this close up. Why, though, do most scientists expect Philae to find pre-biotic chemistry? Is there any chance of life? Also, where else in the solar system can we look?

With infectious diseases increasing worldwide, the need to understand how and why disease outbreaks occur is becoming increasingly important. Looking for answers, a team of biologists found broad evidence that supports the controversial 'dilution effect hypothesis,' which suggests that biodiversity limits outbreaks of disease among humans and wildlife. 

"The dilution effect hypothesis is important because it warns that human-mediated biodiversity losses can exacerbate disease outbreaks, yet it has been contentiously debated," said study lead author Dr. David Civitello, postdoctoral researcher in the Department of Integrative Biology at University of South Florida. 

Child fitness levels are falling at an even faster rate than first feared - and it has nothing to do with obesity, according to a new study. Of more than 300 pupils aged between 10 and 11 who took part, the researchers expected that children with a lower BMI would do better than the heavier children they measured six years ago.

But the follow-up to a 2009 study showed child fitness declined by 8% over the previous ten years - yet the children they tested were actually thinner than those measured in 2008. 

There is no longer any doubt: We are entering a mass extinction that threatens humanity's existence, according to a rather ridiculous claim by doomsday prophet Professor Paul Ehrlich, the same author of the Population Bomb who has been saying this same thing since the 1960s.

 Ehrlich and fellow hysterics Anthony D. Barnosky of the University of California at Berkeley, Andrés García of Universidad Autónoma de México, Robert M. Pringle of Princeton University and Todd M. Palmer of the University of Florida, say there are threatened species, too many humans, and issues with habitat. 

Every president for more than 30 years has required executive branch agencies to analyze regulatory impacts before issuing new requirements.

They’ve relied on the Office of Information and Regulatory Affairs (OIRA) in the Office of Management and Budget to review significant new rules to ensure the quality of such regulatory analysis.

New, ultra-high-field magnetic resonance images (MRI) of the brain provide the most detailed images to date to show that while the brain shrinks with age, brain cell density remains constant.

The images of cognitively normal young and old adults provide the first evidence that in normal aging, cell density is preserved throughout the brain, not just in specific regions, as previous studies on human brain tissue have shown. The findings also suggest that the maintenance of brain cell density may protect against cognitive impairment as the brain gradually shrinks in normal aging.

Doctors often misdiagnose zinc deficiency, and seem to be unaware of the impact of excess zinc on the body, according to a small audit of clinical practice.

Zinc is an essential trace element that is required in daily quantities of 5.5 to 9.5 mg for men, and 4 to 7 mg for women. But zinc supplements are usually only available in formulations of 45 or 50 mg. The US recommended tolerable limit is 40 mg/day.

I’m generally optimistic about the ability of the world’s farmers to continue to feed the growing population, and also to satisfy the increased food demand of the growing middle class in previously poor countries. That hope is based on the amazing track record of innovation by farmers and their technological supporters that I have witnessed over the past four decades. I do, however, have some significant concerns about trends and factors that may compromise the farming enterprise over the next critical decades.

Working women are "leaning in" and supporting more females in leadership roles, but a new study finds that having a female manager doesn't necessarily equate to higher salaries for female employees.

Instead, women can sometimes take an earnings hit relative to their male colleagues when they go to work for a female manager.