- Black holes have hair.
Forty years ago, Stephen Hawking scandalized the entire physics community when he suggested that black holes emit radiation. Although black holes are conventionally described as entities from which nothing, not even light, can escape, it turns out that some particles do escape, and they take energy with them as they do so. This means that, if nothing new falls into a black hole, it will eventually evaporate as it runs out of energy from escaping particles.
Dr. Hawking concluded that with the demise of the black hole came the destruction of all physical information about the matter inside. This destruction of information violates one of the presumed laws of quantum physics – like matter, information can neither be created nor destroyed. This is known as the black hole information paradox. Even today, more than forty years later, this paradox has not been resolved. However, in a paper written by Hawking himself and published in Physical Review Letters on June 6, one piece of the puzzle seems to have been solved.
The piece of the puzzle is the overturning of the assumption that black holes are “hairless,” a somewhat peculiar term to describe the idea that, to an outside observer, information within a black hole is invisible. Even someone like myself, whose understanding of black holes rivals that of a slightly precocious third grader, assumes this concept to be true. Anything that goes into a black hole is gone forever (unless you go into the black hole too*). Even with fancy instruments, we shouldn’t be able to tell what’s inside a black hole.
Hawking and his colleagues Drs. Perry and Strominger determined that, actually, black holes are surrounded by “soft hair,” zero-energy gravitons and photons which do contain information about the matter within a black hole. What this means is that information inside a black hole may not actually disappear when the black hole does, suggesting the information is not destroyed and the law about information conservation is not broken. The information paradox still lacks a complete solution – many brilliant physicists, including Stephen Hawking, have been chipping away at an answer for years. But this discovery bring us one step closer to a “theory of everything,” a single theory which would explain why the universe works the way it does.
*I have it on good authority that you will resemble spaghetti if you attempt this.
- Autism involves more than just the brain.
If you know someone with autism spectrum disorder (ASD), you are probably familiar with the social difficulties and repetitive behaviors that often characterize the disorder. You may also have noticed this person seems to have a different response to touch than you do (if you are autistic, you may be able to attest that certain touches bother you more or less than they do others). For example, certain clothing may feel absolutely unbearable to an autistic person; social touch, such as hugs and handshakes, may be quite uncomfortable. Conversely, some autistic people have a very high pain tolerance, and for many, the feel of a heavy or weighted blanket is comforting.
We’ve known about the link between sensory dysfunction and ASD for quite some time, but still, most research has focused on how autism affects the brain rather than how it affects the peripheral nervous system (the nerves outside the brain that respond to pain and touch). A recent paper published in Cell focused on exactly why autism is associated with sensory and tactile differences.
The study used mice lacking genes that are often mutated in humans with autism. Importantly, these genes were deleted only in the peripheral nervous system, not in the brain or anywhere else in the body. The study found that these deletions were enough to cause tactile sensitivity problems in the mice, and also that the mice displayed anxious behavior and impaired social interactions.
The researchers then asked another question – does it matter when the genes are deleted? In most genetic mouse models, genes are altered from birth, but it is also possible to change or delete genes in adult mice. The study found that, when genes were deleted in adult mice that were allowed to develop normally as babies, they experienced the same problems with touch. However, they do not experience the same behavioral deficits. The paper therefore proposed that response to touch during a critical developmental window can affect behavior throughout life. Studies like this one may help therapists and caregivers understand the links between sensory experience and social and behavioral problems. This in turn could inform better strategies for accommodating and helping autistic children, especially in early childhood.
Jessica (Editor) Jess is a fourth year biology PhD student who studies the liver and its regenerative capabilities. In her admittedly limited free time, she enjoys traveling, writing, and being outdoors.