What is a Black Hole?

Black Holes are the Remnants of Very Massive Stars 
Black holes may be among the strangest – and most commonly misunderstood – objects in our universe. The remnants of the most massive stars, they sit at the limit of our understanding of physics. They can contain several times the mass of our sun in a space no larger than a city. With gravity so intense that not even light can escape their surfaces, black holes can teach us about the absolute extremes in the cosmos and the very structure of space itself.
Conceptually, black holes aren’t all that complicated. They are nothing more than extremely dense cores of once-massive stars. Most stars, like our sun, end their lives peacefully by gently blowing their outer layers into space. But stars exceeding about eight times the mass of the sun take another, more dramatic, path.
These stars die when they can no longer fuse atomic nuclei in their core. It’s not that they run out of fuel, per se. Rather, once the star has a core of iron, fusing together atoms to make new elements actually costs the star energy. Lacking an energy source, the star can’t hold itself up against the relentless struggle with gravity. The outer layers of the star come crashing down.
As several octillion tons of gas come hurdling down, the star’s core undergoes a drastic change and becomes resilient to further compression. The infalling gas hits the now-hardened core and rebounds. The rapid gas compression sets off one last wave of uncontrolled nuclear fusion. The star, now wildly out of balance, explodes. The resulting supernova can outshine an entire galaxy and can be seen from across the universe.
In the supernova’s wake, the core remains. This dense soup of subatomic particles has a couple of options at this point. For a star with less mass than 20 suns, the core holds together as a neutron star. But for the real stellar heavyweights, the core transforms into a truly exotic object. A black hole is born.
Stars thrive in a precarious balance. Gravity wants to pull the star together, internal pressure wants to tear it apart. The most drastic changes happen when one of these forces gets the upper hand. Above a core mass of a few suns, there is no known source of pressure that can balance gravity. The stellar remnant collapses upon itself.
Squeezing all that mass into a smaller and smaller volume makes the gravity at the dead star’s surface skyrocket. Ratcheting up the gravity makes it increasingly difficult for anything to escape. Get the gravity high enough – about 30 thousand times what we feel here on Earth – and some truly bizarre side effects pop up.
Throw a ball up into the air, and eventually it stops, turns around, and comes back to your hand. Throw the ball harder, it goes higher – but still falls back down. Throw the ball hard enough and the ball can escape Earth’s gravity. That point-of-no-return is called the “escape velocity”. It’s different for every planet, star, and comet. Earth’s escape velocity is about 40,000 km/hr. For the sun, it’s over 2 million km/hr!. On a very small asteroid, jumping too high might accidentally launch you into orbit.
On a black hole, however, the escape velocity is greater than the speed of light!
Since nothing can go that fast, then nothing – not even light itself – can get up enough speed to escape a black hole’s surface. No type of radiation—radio waves, UV, infrared – can emanate from a black hole. No information at all can ever leave. The universe has drawn a curtain around whatever remains of these stellar behemoths and so we can’t directly study them. All we can do is conjecture.
The black hole itself is defined by a volume of space delineated by an “event horizon”. The event horizon invisibly marks off the boundary where the escape velocity is exactly equal to the speed of light. Outside of the horizon, your spaceship has at least a theoretical chance of making it home. Crossing that line sets you on a one-way journey to whatever sits inside.
What sits within the event horizon is a complete mystery. Is there still an object sitting in the center, some shadow of a once brilliant stellar core? Or does nothing stop the gravity from crushing the nuclei to a single point, possibly even puncturing the fabric of space-time? Our lack of understanding of such extreme environments and the veil of ignorance that cloaks these creatures gives the imagination room to run wild. Visions of tunnels to other dimensions, parallel universes, and even distant times are rampant. But the only honest answer to the question “what lies beyond the event horizon?” is a simple “we don’t know!”
The bottom line is that black holes are the burying grounds of extremely massive stars. Following a supernova explosion, the massive core is left behind. Lacking a suitable balancing force, gravity pulls the core together to a point where the escape velocity exceeds the speed of light. From this point on, no light – and no information of any kind – can radiate into space. All that remains is a perfectly black void where once a mighty star stood.

Your Brain on Sugar

Wait! Before you eat that ice cream …..

Did you know that binging on soda and sweets – for as little as six weeks – might do damage to your memory?
A new study suggests that a diet high in fructose – that is, sugars commonly derived from sugar cane, beets and corn – can slows your brain, hampering your memory and learning. Fortunately, this same study also suggests that eating foods that contain nutrients called omega-3 fatty acids – like walnuts, salmon, flax seeds and sardines – can counteract these negative effects.
The study, headed by neuroscientist Fernando Gomez-Pinilla at the University of California Los Angeles, focused on high-fructose corn syrup, an inexpensive liquid that’s six times sweeter than cane sugar. It’s used in many processed foods, including soft drinks, condiments, apple sauce and baby food. According to the U.S. Department of Agriculture, the average American consumes more than 40 pounds of high-fructose corn syrup every year.
The study monitored two groups of rats. Each were fed regular food and trained on a maze twice daily for five days. They were then switched to a diet high in fructose for six weeks.
One group also received omega-3 fatty acids, which protect against damage to synapses — the chemical connections between brain cells that enable memory and learning.
After six weeks on their experimental diet, the rats were tested on the mazes again.
Of the two groups, the rats that received fructose without a supplement of omega-3 fatty acids were slower at completing the maze, and their brain cells had trouble signaling each other, disrupting the rats’ ability to think clearly and recall the maze route.

So what does this mean for us humans? In short, what you eat might have a big impact on how your brain functions.

Tumeric Stops Rift Valley Fever

Turmeric Spices Up Virus Recently Discovered

The popular spice turmeric packs more than just flavor — it shows promise in fighting devastating viruses, Mason researchers recently discovered.

Curcumin, found in turmeric, stopped the potentially deadly Rift Valley Fever virus from multiplying in infected cells, says Aarthi Narayanan, lead investigator on a new study and a research assistant professor in Mason’s National Center for Biodefense and Infectious Diseases.

Mosquito-borne Rift Valley Fever virus (RVF) is an acute, fever- causing virus that affects domestic animals such as cattle, sheep and goats, as well as humans. Results of the study were publishedthis month in the Journal of Biological Chemistry.

“Growing up in India, I was given turmeric all the time,” says Narayanan, who has spent the past 18 months working on the project. “Every time my son has a throat infection, I give (turmeric) to him.”

There’s more work to do before curcumin-based pharmaceuticals become commonplace, Narayanan emphasizes. She plans to test 10 different versions of curcumin to determine which one works the best. She also intends to apply the research to other viruses, including HIV.

Narayanan has long wanted to explore the infection-fighting properties of turmeric, in particular its key component, curcumin. “It is often not taken seriously because it’s a spice,” she says.

But science is transforming the spice from folk medicine to one that could help a patient’s body fight off a virus because it can prevent the virus from taking over healthy cells. These “broad-spectrum inhibitors” work by defeating a wide array of viruses.

“Curcumin is, by its very nature, broad spectrum,” Narayanan says.

“However, in the published article, we provide evidence that curcumin may interfere with how the virus manipulates the human cell to stop the cell from responding to the infection.”

Kylene Kehn-Hall, a co-investigator on the study, adds, “We are very excited about this work, as curcumin not only dramatically inhibits RVFV replication in cell culture but also demonstrates efficacy against RVFV in a mouse model.”

Narayanan and her colleagues study the connection between a virus and how it impacts the host — human or animal. Symptoms clue in the researcher about the body’s inner workings. Rift Valley Fever and Venezuelan Equine Encephalitis kick off with flu-like symptoms.

Symptoms can make it challenging for someone to recover. The body usually starts with an exaggerated inflammatory response because it doesn’t know where to start to rid itself of the virus, she says.

“Many times, the body goes above and beyond what is necessary,” Narayanan says. “And that’s not good because it’s going to influence a bunch of cells around the infection, which haven’t seen the bug. That’s one way by which disease spreads through your body. And so it is very important to control the host because a lot of times the way the host responds contributes to the disease.”

Controlling the symptoms means more than simply making the patients feels better. “You’re giving the antiviral a chance to work. Now an antiviral can go in and stop the bug. You’re no longer trying to keep the host alive and battling the bug at the same time.”

Once Narayanan knows how the body responds to a virus, it’s time to go after the bug itself.

She’s applying this know- how to a family of viruses called Bunyaviruses, which feature Rift Valley fever, and such alphaviruses as Venezuelan equine encephalitis and retroviruses, which notably include HIV.

She delves into uncovering why and how each virus affects the patient. “Why are some cell types more susceptible to one type of infection than another?”

HIV goes after the immune system. Bunyaviruses will infect a wide range of cells but do maximum damage to the liver.

“What is it about the liver that makes it a sitting duck compared to something like the brain?” Narayanan asks.

Ultimately, curcumin could be part of drug therapies that help defeat these viruses, Narayanan says.

“I know this works. I know it works because I have seen it happen in real life,” Narayanan says. “I eat it every day. I make it a point of adding it to vegetables I cook. Every single day.”

Other Mason researchers involved in the study are Charles Bailey, Ravi Das, Irene Guendel, Lindsay Hall, Fatah Kashanchi, Svetlana Senina and Rachel Van Duyne. Several researchers from other institutions also collaborated.