Merging Black Holes Could Give Astronomers a Way to Detect Hawking Radiation

Simulation of merging supermassive black holes. Credit: NASA's Goddard Space Flight Center/Scott Noble
Simulation of merging supermassive black holes. Credit: NASA's Goddard Space Flight Center/Scott Noble

Nothing lasts forever, including black holes. Over immensely long periods of time, they evaporate, as will other large objects in the Universe. This is because of Hawking Radiation, named after Stephen Hawking, who developed the idea in the 1970s.

The problem is Hawking Radiation has never been reliably observed.

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The Universe Could Be Filled With Ultralight Black Holes That Can't Die

This simulated image shows how black holes bend a starry background and capture light. Credit: NASA’s Goddard Space Flight Center

It’s that time again! Time for another model that will finally solve the mystery of dark matter. Or not, but it’s worth a shot. Until we directly detect dark matter particles, or until some model conclusively removes dark matter from our astrophysical toolkit the best we can do is continue looking for solutions. This new work takes a look at that old theoretical chestnut, primordial black holes, but it has a few interesting twists.

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If Black Holes Evaporate, Everything Evaporates

How virtual particles radiate away from any mass. Credit: Wondrak, et al

Hawking radiation is one of the most famous physical processes in astronomy. Through Hawking radiation, the mass, and energy of a black hole escape over time. It’s a brilliant theory, and it means that black holes have a finite lifetime. If Hawking radiation is true. Because as famous as it is, Hawking radiation is unproven. The theory is not even theoretically proven.

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A new way to Confirm Hawking's Idea That Black Holes Give off Radiation

In honor of Dr. Stephen Hawking, the COSMOS center will be creating the most detailed 3D mapping effort of the Universe to date. Credit: BBC, Illus.: T.Reyes

Nothing can escape a black hole. General relativity is very clear on this point. Cross a black hole’s event horizon, and you are forever lost to the universe. Except that’s not entirely true. It’s true according to Einstein’s theory, but general relativity is a classical model. It doesn’t take into account the quantum aspects of nature. For that, you’d need a quantum theory of gravity, which we don’t have. But we do have some ideas about some of the effects of quantum gravity, and one of the most interesting is Hawking radiation.

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There are 6×10^80 Bits of Information in the Observable Universe

Since the beginning of the Digital Age (ca. the 1970s), theoretical physicists have speculated about the possible connection between information and the physical Universe. Considering that all matter is made up of information that describes the state of a quantum system (aka. quantum information), and genetic information is coded in our DNA, it’s not farfetched at all to think that physical reality can be expressed in terms of data.

This has led to many thought experiments and paradoxes, where researchers have attempted to estimate the information capacity of the cosmos. In a recent study, Dr. Melvin M. Vopson – a Mathematician and Senior Lecturer at Portsmouth University – offered new estimates of how much information is encoded in all the baryonic matter (aka. ordinary or “luminous” matter) in the Universe.

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We Knew Black Holes Have a Temperature. It Turns out They Also Have a Pressure

Artist view of an active supermassive black hole. Credit: ESO/L. Calçada

In the classical theory of general relativity, black holes are relatively simple objects. They can be described by just three properties: mass, charge, and rotation. But we know that general relativity is an incomplete theory. Quantum mechanics is most apparent in the behavior of tiny objects, but it also plays a role in large objects such as black holes. To describe black holes at a quantum level, we need a theory of quantum gravity. We don’t have a complete theory yet, but what know so far is that quantum mechanics makes black holes more complex, giving them properties such as temperature and perhaps even pressure.

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Hawking Made a Prediction About Black Holes, and Physicists Just Confirmed it

Computer simulation of plasma near a black hole. Credit: Hotaka Shiokawa / EHT

On its own, a black hole is remarkably easy to describe. The only observable properties a black hole has are its mass, its electric charge (usually zero), and its rotation, or spin. It doesn’t matter how a black hole forms. In the end, all black holes have the same general structure. Which is odd when you think about it. Throw enough iron and rock together and you get a planet. Throw together hydrogen and helium, and you can make a star. But you could throw together grass cuttings, bubble gum, and old Harry Potter books, and you would get the same kind of black hole that you’d get if you just used pure hydrogen.

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A New Idea to Harness Energy From Black Holes

Credit: Francis Reddy/NASA GSFC

Fifty years ago, English mathematical physicist and Nobel-prize winner Roger Penrose proposed that energy could be extracted from the space around a rotating black hole. Known as the ergosphere, this region lies just outside an event horizon, the boundary within which nothing can escape a black hole’s gravitational pull (even light). It is also here where infalling matter is accelerated to incredible speeds and emits all kinds of energy.

This became known as the Penrose Process, which many theorists have since expanded on. The latest comes from a study conducted by researchers from Columbia University and the Universidad Adolfo Ibáñez in Chile. With support from organizations like NASA, they demonstrated how a better understanding of the physics at work around spinning black holes could allow us to harness their energy someday.

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You Could Travel Through a Wormhole, but it’s Slower Than Going Through Space

Artist illustration of a spacecraft passing through a wormhole to a distant galaxy. Image credit: NASA.
Artist illustration of a spacecraft passing through a wormhole to a distant galaxy. Image credit: NASA.

Special Relativity. It’s been the bane of space explorers, futurists and science fiction authors since Albert Einstein first proposed it in 1905. For those of us who dream of humans one-day becoming an interstellar species, this scientific fact is like a wet blanket. Luckily, there are a few theoretical concepts that have been proposed that indicate that Faster-Than-Light (FTL) travel might still be possible someday.

A popular example is the idea of a wormhole: a speculative structure that links two distant points in space time that would enable interstellar space travel. Recently, a team of Ivy League scientists conducted a study that indicated how “traversable wormholes” could actually be a reality. The bad news is that their results indicate that these wormholes aren’t exactly shortcuts, and could be the cosmic equivalent of “taking the long way”!

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Stephen Hawking has passed away at age 76

Hawking has experienced zero gravity before, when he flew on Zero Gravity Corp's modified Boeing 727 in 2007. Image: By Jim Campbell/Aero-News Network

Dr. Stephen Hawking, the famed British theoretical physicist, science communicator, author and luminary, passed away in the early hours on Wednesday, March 14th. According to a statement from his family, the renowned scientist died peacefully in his home at Cambridge. He was 76 years old, and is survived by his first wife, Jane Wilde, and their three children – Lucy, Robert and Tim.

Dr. Hawking spent the past 50 years living with a terminal illness that slowly deprived him of his speech and the use of much of his body. He also leaves behind an unparalleled scientific legacy and millions of people worldwide who admired him for his genius, his sense of humor, and the way he sought to educate people on the importance of scientific research, space exploration, and disability awareness.

In 1963, when he was just 21 years old, Dr. Hawking was diagnosed with Amyotrophic Lateral Sclerosis (ALS, aka. Lou Gehrig’s disease), a degenerative form of motor neurone disease that would be with him for the rest of his life. At the time, he was told that he had only two years to live. This diagnosis caused Dr. Hawking to fall into a depression and lose interest in his studies, which he was pursuing at Cambridge University at the time.

Stephen Hawking and Jane Wilde on their wedding day, July 14th, 1966. Credit:

However, his outlook soon changed as the disease progressed slower than his doctor’s originally though. It was also around this time that Hawking met his first wife, Jane Wilde. The two became engaged in October of 1964 and married on July 14th, 1966. Hawking would later say that his relationship with Wilde gave him “something to live for”.

The slow progression of the disease also allowed Dr. Hawking to embark on a career marked by brilliance, brashness, and original thinking. Among his many achievements, Dr. Hawing was the Lucasian Professor of Mathematics at the University of Cambridge, the Founder of the Center for Theoretical Cosmology, and served as the Sally Tsui Wong-Avery Director of Research at the Department of Applied Mathematics and Theoretical Physics until his passing.

During his lifetime, Dr. Hawking made invaluable contributions to the fields of theoretical physics and cosmology. These include his extensive work on gravitational singularity theorems (in collaboration with Roger Penrose), the theory that black holes emit radiation (often called Hawking Radiation), and a theory of cosmology that attempted to unify general relativity and quantum mechanics (aka. Theory of Everything).

OPeter Higgs and Stephen Hawking visiting the “Collider” exhibition at London’s Science Museum (Image: c. Science Museum 2013)

His many accolades, honors and awards included being made an Honorary Fellow of the Royal Society of Arts (FRSA), a lifetime member of the Pontifical Academy of Sciences, and a recipient of the Presidential Medal of Freedom – the highest civilian award in the United States. In 2002, Hawking was ranked number 25 in the BBC’s poll of the 100 Greatest Britons.

The many books he penned include the best-selling A Brief History of Time, A Briefer History of Time, the essay collection Black Holes and Baby Universe, The Universe in a Nutshell, The Grand Design (which he co-authored with famed Caltech theoretical physicist and best-selling author Leonard Mlodinow) and his autobiography, My Brief History.

In 2007, Hawking and his daughter Lucy also published George’s Secret Key to the Universe, a children’s book designed to explain theoretical physics in an accessible fashion and featuring characters similar to those in the Hawking family. The book was followed by three sequels – George’s Cosmic Treasure Hunt (2009), George and the Big Bang (2011), George and the Unbreakable Code (2014).

President Barack Obama talks with Stephen Hawking in the Blue Room of the White House before a ceremony presenting him and 15 others the Presidential Medal of Freedom, August 12, 2009. (Official White House photo by Pete Souza)

In a statement by his three children, Lucy, Robert and Tim praised their father’s courage and persistence and honored how his genius and sense of humor inspired people all across the world:

“We are deeply saddened that our beloved father passed away today. He was a great scientist and an extraordinary man whose work and legacy will live on for many years… He once said, ‘It would not be much of a universe if it wasn’t home to the people you love.’ We will miss him forever.”

News of his passing was also met with a flurry of condolences by friends, colleagues, fans, and people whose lives he touched over the years. NASA tweeted the following early this morning, followed by a video of Dr. Hawking addressing the astronauts of the ISS in 2014:

Famed scientists and science communicator Neil DeGrasse Tyson also expressed his condolences, tweeting:

The cast of the Big Bang Theory, one of the many hit TV shows that Dr. Hawking made several appearances on, also offered their condolences and admiration:

The Motor Neurone Disease Association – of which Prof Hawking had been a patron since 2008- also expressed condolences on both their Facebook and twitter feeds. In addition, they reported that its website had crashed because of an influx of donations to the charity.

Despite having lived for five decades with this degenerative disease, Hawking had a very practical and courageous attitude about life. In 2011, he said in an interview with The Guardian that death was never far from his mind. “I have lived with the prospect of an early death for the last 49 years,” he said. “I’m not afraid of death, but I’m in no hurry to die. I have so much I want to do first.”

Hawking, a well-known atheist, was also clear on his thoughts on an afterlife. “I regard the brain as a computer which will stop working when its components fail,” he said. “There is no heaven or afterlife for broken down computers; that is a fairy story for people afraid of the dark.”

Dr. Hawking’s life and his contributions to science have been commemorated in many ways over the years. A film version of A Brief History of Time, directed by Errol Morris and produced by Steven Spielberg, premiered in 1992.  In 1997, a six-part television series Stephen Hawking’s Universe premiered on PBS, with a companion book also being released. In 2014, the story of his diagnosis and the impact it had on his young family was showcased in the Oscar-winning film The Theory of Everything.

Stephen Hawking is a major proponent for colonizing other worlds, mainly to ensure humanity does not go extinct. Credit:

Dr. Hawking has also been a major role model for people dealing with disabilities and degenerative illnesses and played an unparalleled role when it came to disability awareness and outreach. In 1999, he and eleven other luminaries joined with Rehabilitation International , an organization founded in 1922 “To advance the rights and inclusion of persons with disabilities across the world.”

In 2000, Dr. Hawking and his fellow luminaries signed the Charter for the Third Millennium on Disability, which called on governments around the world to prevent disabilities and protect disability rights. Throughout his life, Dr. Hawking also remained a committed educator  – personally supervising 39 successful PhD students – and lending his voice to scientific and humanitarian goals.

These include Breakthrough Initiatives, an effort to search for extraterrestrial intelligence (SETI) in the Universe, which Dr. Hawking helped launch in 2015. That same year, he also used his influence and celebrity status to promote the The Global Goals, a series of 17 goals adopted by the United Nations Sustainable Development Summit to end extreme poverty, social inequality, and fixing climate change over the course of the next 15 years.

To commemorate his life and legacy, a book of condolence has been opened at Gonville and Caius College in Cambridge, where Prof Hawking was a fellow. All around the world, there are outpourings of remembrance and support for his family from people who are mourning Dr. Hawking’s passing and celebrating his life and achievements.

As Neil DeGrasse Tyson said, the death of Dr. Hawking has left a vacuum in the scientific community, and in the hearts of people everywhere. However, his life and his many contributions shall be remembered for a long time to come!

Further Reading: Stephen Hawking, BBC, The Guardian,