Faster-than-light neutrinos mean Einstein is wrong! At least, that’s what some popular press articles have suggested since researchers with the OPERA experiment in Italy presented evidence of neutrinos arriving 60 nanoseconds earlier than thought possible.
But scientists, quite intrigued by the anomalous results, have since been busy generating more measured responses. In the three weeks after the announcement, more than 80 explanations have been posted to the preprint server arxiv. While some suggest the possibility of new physics, such as neutrinos that aretraveling through extra dimensions or neutrinos at particular energies traveling faster than light, many offer less revolutionary explanations for the OPERA experiment.
One of the earliest objections to the faster-than-light interpretation came from an astrophysical observation. In 1987, a powerful supernova showered Earth with light and neutrinos. While neutrino detectors observed neutrinos arriving about three hours before the light, this was due to the lightweight particles getting a head start. Neutrinos, which hardly interact with matter, escaped the exploding stellar core with relative ease while photons, absorbed and re-emitted by the various elements, took longer to flee. If the effect from OPERA were as large as observed, scientists have calculated that the neutrinos should have arrived more than four years in advance of the light.
Other scientists have taken the faster-than-light results to task using the Standard Model of physics, which describes all known subatomic particles and their interactions. According to the Standard Model, neutrinos at sufficiently high energies should produce a virtual electron-positron pair through a process known at Cohen-Glashow emission. As explained in a paper by Nobel laureate Sheldon Glashow and his colleagues, these emanations would have sapped energy from the faster-than-light neutrinos, causing them to slow down.
Theoretical physicist Matt Strassler also noted on his blog that the Standard Model’s properties suggest that making neutrinos go faster than light requires electrons to do the same. But if electron neutrinos moved at the speed suggested by the OPERA experiment, then electrons should also travel faster than the speed of light by at least one part in 1,000,000,000, or one billionth. Experiments have established theoretical limits that electrons remain subliminal at a precision down to more than 5 part in a thousand trillion, effectively ruling this scenario out.
Among the most recent ideas is a paper invoking Einstein’s supposedly challenged theory of relativity. The OPERA team used GPS satellites to accurately measure the 730-km distance between their detector and the CERN beam where the neutrinos were produced. Yet, according to special relativity, calculations will be slightly different when two observers are moving relative to one another.
Since the satellites were zipping around the Earth, the positions of the neutrino source and the detector changed. According to the paper, the movement would account for a 64 nanoseconds discrepancy, nearly exactly what the OPERA team observes.
Ultimately, it will take a great deal more time and scholarship before the physics community settles on the true explanation for the OPERA results. Until then, vigorous debate is likely to continue.
Forensic DNA databases are a potentially powerful law enforcement tool, but may disproportionately target poor and dark-skinned wrongdoers, biotechnologically magnifying flaws in criminal justice systems.
“Forensic DNA databases are growing to mirror racial disparities in arrest practices and incarceration rates,” write sociologists Troy Duster and Peter Chow-White in an Oct. 4 Public Library of Science Medicine essay.
In the last decade, as DNA became the gold standard of forensic evidence, DNA collection by law enforcers became routine. At least 56 countries have a national DNA database. In the United States, the FBI’s database contains 5 million profiles, and DNA is also gathered at state and local levels, where a patchwork of laws govern how it’s collected and managed. Some states gather DNA from anyone arrested for a felony, or use so-called “DNA dragnets” to gather samples from anyone in geographical proximity to a crime. And samples may be kept indefinitely, even if suspects are cleared of charges.
Civil rights advocates have warned that demographically unbalanced forensic DNA data banks could “create a feedback loop.” Because samples are stored and compared against DNA collected at future crime scenes, police will be more likely to pursue crimes committed by members of overrepresented groups, while underrepresented groups can more easily evade detection.
The potential for problems expands when states permit so-called familial DNA searches, in which police who can’t find a database match to crime scene DNA can search the database for partial matches, ostensibly from the suspect’s family and relatives, who can then be targeted. It’s even possible to imaginesituations in which some races or groups become universally covered, while others remain only partially surveyed.
According to Duster and Chow-White, this represents a biotechnological aspect of the “digital divide,” a term better known from debates in the 1990s, meaning that the internet’s benefits could be unfairly distributed. It might sound strange in this context, but “DNA technology is information technology,” said Chow-White. “DNA is closely tied to our analog ideas of biology, to blood and kin. But when DNA turns into digital code, much like when our lives turn into digital code,” the consequences become social and networked.
Ironically, the overrepresentation of minorities in forensic DNA databases has occurred even as they’ve become underrepresented in medical genetics research, said Chow-White and Duster.
As for criminal justice, the solutions aren’t clear. Some people have advocated taking DNA from everyone. Others say a universal database violates Fourth Amendment protections against unreasonable searchesand betrays the principle of presumed innocence.
Duster and Chow-White have no prescription, but “the first and foremost step in addressing the problem is recognizing that this is an issue,” they write. “We cannot address the problem unless or until there is awareness.”Citation: “Do Health and Forensic DNA Databases Increase Racial Disparities?” By Peter Chow-White and Troy Duster. PLoS Medicine, Vol. 8 No. 10, October 4, 2011
Population growth is one of the main engines driving evolution at a faster pace than ever before
According to the conclusions of a new scientific study, it would appear that evolution in modern humans has entered into full gear. Over the past 40,000 years or so, experts show, the rate at which our species evolves has accelerated remarkably.
The new results are in direct contradiction with the conclusions of other scientific studies, which have proposed that our species has stopped evolving, or that evolution takes place at a very slow pace.
It would appear that exponential population growth and cultural shifts are the primary reasons why we evolve so fast at this point. These data were derived from an examination of data collected by an international genomics project.
The research team, which is based at the University of Wisconsin Madison (UWM), suggests that the pace of evolution has quickened even more in the last 5,000 years, while humanity was still in the Stone Age.
The rate of positive selection has increased 100 times from any other period of human evolution. “We are more different genetically from people living 5,000 years ago than they were different from Neanderthals,” explains UWM anthropologist John Hawks.
The expert, who was the leader of the new research, says that the new study was made possible by impressive advancements made in the science of sequencing and deciphering the basic building code of life, DNA. Genes that allow us to become more fit for survival can now be identified.
Most of the changes human beings now displays appeared in order to allow the body to improve its resistance to microorganisms, or to allow for it to process new foods, that only became available with the advent of agriculture.
“In evolutionary terms, cultures that grow slowly are at a disadvantage, but the massive growth of human populations has led to far more genetic mutations,” Hawks says of the basic of the phenomenon.
“And every mutation that is advantageous to people has a chance of being selected and driven toward fixation. What we are catching is an exceptional time,” he adds, saying that his team mostly looked for single nucleotide polymorphisms (SNP) in the new study.
“Five thousand years is such a small sliver of time -- it's 100 to 200 generations ago. That's how long it's been since some of these genes originated, and today they are in 30 or 40 percent of people because they've had such an advantage. It's like 'invasion of the body snatchers,” Hawks comments.
The work he and his team conducted appears in a paper that was published in the journal Proceedings of the National Academy of Sciences (PNAS),Daily Galaxy reports.
Your memories and dreams could soon be converted to a digital format
In a study that is bound to entice numerous moral and ethical controversies, scientists at the University of California in Berkeley (UCB) announce the development of a new technique that allows them to tap into the human brain's video feed, hijacking the signal for display on computer monitors.
According to the team, this could be used to communicate with comatose patients, enabling doctors to experience whatever the person in front of them is experiencing. In the future, it may even be possible to post videos of one's dreams on YouTube.
But this cutting-edge blend of brain imaging and computer simulation will undoubtedly be used against the people as well, for torture or peering into someone's brain without their consent. This is why the work will cause so much stir. The UCB group was able to obtain this new capability by combining computer models with functional Magnetic Resonance Imaging (fMRI). Together, these two instruments can decode and reconstruct a person's visual signal, albeit with some errors and a lot of fuzziness.
Interestingly, the method also works for moving images, in the sense that scientists can look at a live feed recorded from the brain of a test subject watching a video. The images of researchers' screens also change as the participant views different actions.
At this point, the technology is limited by the fact that it can only see videos we've already seen ourselves. However, the team plans to improve this approach by becoming capable of taping into our dreams and memories as well.
“This is a major leap toward reconstructing internal imagery. We are opening a window into the movies in our minds,” UCB neuroscience professor Jack Gallant explains. He is also the coauthor of a new study detailing the findings, in the September 22 online issue of the journal Current Biology.
“Our natural visual experience is like watching a movie. In order for this technology to have wide applicability, we must understand how the brain processes these dynamic visual experiences,” UCB post-doctoral researcher and lead study author Shinji Nishimoto adds.
“We addressed this problem by developing a two-stage model that separately describes the underlying neural population and blood flow signals. We need to know how the brain works in naturalistic conditions. For that, we need to first understand how the brain works while we are watching movies,” he concludes.