Tag Archives: stephen hawking

Credit: Pixabay.

Sonic black hole confirms Hawking radiation theory

In 1974, the late Stephen Hawking argued in a now-famous study that besides mass and spin, black holes can be characterized by a unique temperature. He also claimed that black holes don’t just devour matter, but also emit radiation. Researchers at the Israel Institute of Technology have set out to test this theory by creating a black hole analog in the lab. The results agreed with Hawking’s predictions, giving more credence to the theory.

Credit: Pixabay.

Credit: Pixabay.

black hole is defined as a region of spacetime whose extremely strong gravity prevents anything, including light, from escaping. This essentially means that we can’t see a black hole directly — although this year astronomers captured a picture of a black hole’s event horizon (the swirling, bright boundary of the black hole). Scientists are confident that black holes exist, judging from their theoretical calculations and observations of X-rays emitted by swirling disks of gas around the black hole. The motions of nearby stars can also infer the presence of a black hole. In fact, most galaxies — the Milky Way included — are thought to be held together by the gravity of supermassive black holes (with masses millions of times that of the sun), which lie at the galactic center.

But if everything gets sucked into a black hole, never to return, what happens to the information that these objects used to hold? According to the laws of quantum mechanics, matter cannot simply disappear without leaving behind information of its previous state. So, on the one hand, we have physics that says information is never truly lost, nor is it truly copied, while on the other hand, we know that an object that gets too close, and crosses the black hole’s event horizon, it can never escape.

This is known as the black hole information paradox — and Stephen Hawking had been trying to crack it for decades. His investigations eventually led him to develop the Hawking radiation theory, in which the physicist argued that not all matter falls into a black hole. In some cases, when entangled pairs of particles are attracted into a black hole, only one of them would fall in, while the other escaped. Hawking named these escaping particles Hawking radiation, theorizing that its nature should be thermal radiation whose temperature would depend on the size of the black hole.

Testing such a theory is virtually impossible because we currently lack the technology required to measure the radiation from a real black hole. Which is why a team of researchers at the Israel Institute of Technology had to come up with a creative solution. For their new study, the authors made a Bose-Einstein condensate (BEC) — the fifth form of matter where familiar physics fades away, and quantum phenomena start to take over, even at a macroscopic scale. BEC matter almost stops behaving as particles and starts behaving more like waves. In a BEC you can observe “waves of atoms”, moving synchronized with each other just like water drops in an ocean wave.

The experimental setup for the black hole analog. Credit: Jeff Steinhauer.

The experimental setup for the black hole analog. Credit: Jeff Steinhauer.

To make BEC, the Israeli researchers trapped 8,000 rubidium atoms in a focused laser beam, chilling matter to only a billionth of a degree above absolute zero. A second laser fired on one side of the BEC made it denser on that side. According to the researchers, this led to a transition that moves at a constant speed through the condensate from the denser area (outside of the black hole) to the less dense area (analogous to the inside of the black hole). This is where it gets a bit tricky: the researchers say that sound waves traveling through the denser region move faster than this transitional flow, allowing sound to move in either direction. However, in the less dense region, sound waves can only travel away from the sharp transition — in other words, further into the black hole analog.

Light can either move away or into a black hole (and never escape) and in this experiment, light was replaced by sound. In experiments, researchers forced one of a pair of phonons (like photons for sound) to fall into the flow of rubidium atoms, while the other was allowed to escape. When the researchers measured both phonons, they recorded an average temperature of .035 billionths of a Kelvin, which agrees with Hawking’s predictions.

These findings in no way prove Hawking’s theory — that would require technology that doesn’t currently exist. However, the study published in Nature shows that Hawking was definitely on to something.

Stephen Hawking at Kennedy Space Center Shuttle Landing Facility. Credit: Wikimedia Commons.

Stephen Hawking’s final paper suggests black holes store information about missing matter in ‘soft hairs’

Stephen Hawking at Kennedy Space Center Shuttle Landing Facility. Credit: Wikimedia Commons.

Stephen Hawking at Kennedy Space Center Shuttle Landing Facility. Credit: Wikimedia Commons.

The eminent physicist Stephen Hawking, who past away last year, was one of the world’s foremost authorities on black holes. Now, colleagues at the universities of Harvard and Cambridge have published the very last paper that lists Hawking as an author, which builds upon the physicist’s lifelong work on these enigmatic cosmic objects. The findings suggest that black holes store some information about the matter they devour in ‘soft hairs’ around the event horizon.

Hairy black holes

A black hole is defined as a region of spacetime whose extremely strong gravity prevents anything, including light, from escaping. This essentially means that we can’t see a black hole directly. However, scientists are confident that they exist, judging from their theoretical calculations and observations of X-rays emitted by swirling disks of gas around the black hole. The motions of nearby stars can also infer the presence of a black hole. In fact, most galaxies — the Milky Way included — are thought to be held together by the gravity of supermassive black holes with masses millions of times that of the sun, which lie at the galactic center.

But if everything gets sucked into a black hole, never to return, what happens to the information that these objects used to hold? According to the laws of quantum mechanics, matter cannot simply disappear without leaving behind information of its previous state. So, on one hand, we have physics that says information is never truly lost, nor is it truly copied, while on the other hand, we know that an object that gets too close, and crosses the black hole’s event horizon, it can never escape.

This is known as the black hole information paradox — and Stephen Hawking had been trying to crack it for decades.

In 1974, Hawking argued in a now-famous study that besides mass and spin, black holes can be characterized by a unique temperature and that they don’t just devour matter, but emit radiation. So it turned out that black holes aren’t entirely ‘black’ — they emit ‘Hawking radiation’, consisting of photons, neutrinos, and to a lesser extent all sorts of massive particles. This has never been observed, mind you, because black holes are obstructed by swirling disks of hot gas that obstruct our view.

But, if black holes indeed have a temperature, then it follows that they must also have entropy — a measure of a physical system’s internal disorder.

Previously, physicists who characterized black holes only by their mass and spin thought that the mysterious objects preserved no trace of the matter they had absorbed. Like bald heads, black holes have “no hairs”, the theory goes.

Hawking himself was also of the opinion that black holes don’t preserve information until very recently. In 2016, he co-authored a paper that suggested that black holes have ‘soft hairs’ of photons that surround the objects and which theoretically preserve information.

In Hawking’s latest and last paper, published posthumously in the preprint server arXiv, Cambridge colleague Malcolm Perry and Harvard University’s Andrew Strominger calculated the entropy of a black hole that has a certain kind of soft hair. Their results agree with Hawking’s original calculation of black-hole entropy.

By no means does this mean that the black hole information paradox has been solved, but the new study provides considerable insight into the issue.

This year, another one of Hawking’s papers has been posthumously published, authored in collaboration with Thomas Hertog, a Belgian physicist at the Catholic University of Leuven. The study proposed that alternate universes do not employ radically different laws of physics and may not actually vary that much from one another. By reducing the multiverse down to a more manageable set of universes which all resemble each other, scientists now have a better chance of arriving at a fully predictive framework of cosmology.

Writing for The Guardian, Perry described the most recently published work as “perhaps the last paper that Stephen was involved in,” but there may be more out there.

Stephen Hawking’s final paper was just published — and it’s mindblowing

Before the eminent physicist died at age 76, Hawking completed a paper that describes a reality made up of multiple universes, but which are not too different to our own. This is Stephen Hawking’s final theory of the cosmos, a work that proposes to simplify the evolution of the last 13.8 billion years since time exists. 

Stephen Hawking at Gonville & Caius College, Cambridge. Credit: Lwp Kommunikáció / Flickr.

Stephen Hawking at Gonville & Caius College, Cambridge. Credit: Lwp Kommunikáció / Flickr.

The new work is the result of a collaboration with Thomas Hertog, who is a Belgian physicist at the Catholic University of Leuven. The pair’s theory is sophisticated (and quite speculative) but not all that difficult to explain. You might have heard about the Big Bang, but modern physics has actually multiple, alternative theories that explain how our universe came to be. One multiverse theory suggests that right after the Big Bang, repeated bursts of ‘cosmic inflation’ occurred which seeded an endless number of pocket universes.

“The usual theory of eternal inflation predicts that globally our universe is like an infinite fractal, with a mosaic of different pocket universes separated by an inflating ocean,” Hawking said in late 2017. 

“The local laws of physics and chemistry can differ from one pocket universe to another, which together would form a multiverse. But I have never been a fan of the multiverse. If the scale of different universes in the multiverse is large or infinite the theory can’t be tested.”

In their new paper, Hawking and Hertog came up with a different take. They propose that the pocket universes that fill space do not employ radically different laws of physics but rather these alternate universe may not actually vary that much from one another. By reducing the multiverse down to a more manageable set of universes which all resemble each other, scientists now have a better chance of arriving at a fully predictive framework of cosmology.

According to the two physicists’ new paper, the eternal inflation model is wrong since Einstein’s theory of general relativity breaks down on quantum scales.

“The problem with the usual account of eternal inflation is that it assumes an existing background universe that evolves according to Einstein’s theory of general relativity and treats the quantum effects as small fluctuations around this,” Hertog explained.

“However, the dynamics of eternal inflation wipes out the separation between classical and quantum physics. As a consequence, Einstein’s theory breaks down in eternal inflation.”

The new paper is based on work done by Hawking and US physicist James Hartle in the 1980s. The theory was revisited and updated with more powerful mathematical techniques used in string theory, where reality is described through the interaction of one-dimensional objects called cosmic strings. Ultimately, this allowed the physicists to reduce eternal inflation to a timeless state on a spatial surface.

“When we trace the evolution of our universe backwards in time, at some point we arrive at the threshold of eternal inflation, where our familiar notion of time ceases to have any meaning,” said Hertog.

Hertog says that the work he’s done with Hawking brings humanity one step closer to understanding the origin of the cosmos. Their assertions could be experimentally tested one day since the theory predicts that if the universe evolved as described, then telltale signs should be recorded in gravitational waves or in the cosmic microwave background, the radiation released by the Big Bang.

“We are not down to a single, unique universe, but our findings imply a significant reduction of the multiverse, to a much smaller range of possible universes,” said Hawking.

Stephen Hawking died on 14 March, at age 76, at his home in Cambridge. His ashes will be laid near the grave of Sir Isaac Newton at Westminster Abey during a thanksgiving service at the end of 2018.

S.W. Hawking and Thomas Hertog. ‘A Smooth Exit from Eternal Inflation?’’ Journal of High-Energy Physics (2018). DOI: 10.1007/JHEP04(2018)147

Why Stephen Hawking Was Afraid of Aliens

Young Stephen Hawking.

Professor Stephen Hawking, the theoretical physicist hailed as one of the most brilliant scientists of the modern age, had genuine anxieties. Thus, intelligence does not necessarily reject fear. Hawking had one fear in particular which deserves noting, namely humanity’s encounter with advanced alien life.

Several of the late physicist’s theories have been shown to be quite accurate and are widely accepted in the scientific community. When he spoke (through his speech synthesizer) people gave ear and were attentive. Like any man, he too had his faults both public and personal. But simply because the man has passed away, does not mean we should disregard what he did and said during his time on Earth.

He made numerous predictions about the present and future problems that the human race faces, involving issues such as overpopulation and artificial intelligence. Perhaps one of his most intriguing and logically-stated beliefs was a concern for detrimental interaction between human beings and extraterrestrial beings.

Unlike astrophysicist Carl Sagan, who was rather optimistic about extraterrestrial contact, Hawking worried about the effects such contact might have on our race, even though the Professor assisted in founding projects to seek intelligent alien organisms. Some may fear aliens as they are depicted in sci-fi and horror stories: ugly creatures capable of taking over human beings and using them as their hosts.

The physical appearance of hypothetical aliens is not what alarmed Stephen Hawking. It was something a bit more sinister. In short, he apparently was cautious of entertaining alien contact because of the possibility that intelligent alien civilizations may want to dominate our race. They might do this either by enslaving people or slaughtering them, or both.

He has related these concerns publicly as early as 2010. In 2016, he speculated that if Earth received a signal of alien origins “we should be wary of answering back.” He further argued this point by employing historical references. “Meeting an advanced civilization could be like Native Americans encountering Columbus,” he said. “That didn’t turn out so well.” Sometime in the future, if we’re not cautious in the search for alien life, humans might rue ignoring Stephen Hawking’s worries about extraterrestrials.

Stephen Hawking: before the Big Bang there was nothing

Professor Stephen Hawking is a world-renowned British theoretical physicist, known for his contributions to the fields of cosmology, general relativity and quantum gravity. He recently sat down with Neil Degrasse Tyson on his “Star Talk” show and it didn’t take long for the talk to get really deep, down to the very origin of the universe but also what came before it.

When asked “what was around before the Big Bang,” Hawking was very uncompromising, simply answering that there was “nothing.” The physicist goes on to explain that Einstein’s Theory of General Relativity states that time and space form a continuum, “which is not flat but curved by the matter and energy in it.”

To answer what happened before the Big Bang, Hawking took a so-called Euclidian approach to quantum gravity to describe the beginning of the universe. What does that mean? According to Hawking, this means that ordinary time is replaced by imaginary time, and this imaginary time “behaves like a fourth direction of space.”

Hawking’s model claims that the history of the universe is a four-dimensional curved surface, just like the surface of the Earth but with two additional dimensions. What’s more, the boundary condition of the universe (the known and constraint value that must be true for the problem that you are working)… is that it has no boundary. In other words, there was no time before the beginning of the universe.

“One can regard imaginary and real time as beginning at the South Pole which is a smooth point of space-time where the normal laws of physics hold. There was nothing south of the South Pole so there was nothing around before the big bang,” Hawking explained.

That’s a pretty mind-blowing statement and although it comes from a foremost authority in cosmology like Hawking, the jury is still out on whether that was really the case or not.




Stephen Hawking revises his deadline for humans escaping Earth — it’s now just 100 years

Last November, Stephen Hawking said humanity needs to establish itself on another planet in the next 1,000 years or risk extinction. We probably did something very wrong since then, as Hawking revised his deadline — we’ve got to get out in the next century.

Stephen Hawking in front of sun with coronal mass ejections.

Image credits Lwp Kommunikáció / Flickr.

In a new BBC documentary titled “Expedition New Earth”, which will debut this summer as part of the program’s science season, Stephen Hawking has severely cut down on his initial deadline set in November. From a full millennium, we’re now down to one hundred years, a number disturbingly close to the length of a human lifetime.

So what prompted this change?

“Professor Stephen Hawking thinks the human species will have to populate a new planet within 100 years if it is to survive,” an online BBC statement reads. “With climate change, overdue asteroid strikes, epidemics and population growth, our own planet is increasingly precarious.”

“In this landmark series, Expedition New Earth, he enlists engineering expert Danielle George and his own former student, Christophe Galfard, to find out if and how humans can reach for the stars and move to different planets.”

The documentary gives Hawking a chance to detail the evolving science and technology, from rockets to astronomy to suspended animation, that will underpin any attempt to survive on another planet, BBC notes. And to be sure, Earth does have a lot on its plate right now. A spare human civilization somewhere in the Universe would be awesome, but is it feasible?


Let’s start with “where”. In the Professor’s own words, Mars is “the obvious next target” for colonization but it’s not exactly lush right now. We’re making progress on establishing supply lines on-planet for oxygen and building materials and food, but that’s only scratching the surface of the issue. The fact remains that without its atmosphere Mars has deadly temperature shifts, nothing to breathe, and nothing to shield against radiation. Taken together, all these factors would immensely limit any budding community on the planet, let alone a civilization. Given time to work their magic, scientists and engineers could probably turn Mars into a very welcoming home — just not right now. A colony would require a steady stream of supplies from Earth to function, and that’s not really an option if society breaks down (or under a slab of space-rock) back on good ole Earth.


Image credits Aynur Zakirov.

The next option is to look farther away. Odds are on our side to find a human-habitable planet somewhere in the galaxy, but with so many to sort through it’s going to take time. Our telescopes can give us a general feel of the planets we look at, but can’t peer on the surface to let us know what to expect down there. And lastly, we need to consider if humanity can make a trip of hundreds of years to a new home.

Can we even build a ship to withstand that in time? Not now. The best ships we have at the moment are intended to carry up to six people on NASA’s mission to Mars. Very nice for their intended role, impressively ill-suited to ferrying humanity somewhere else. The most ambitious ship designs in the works are probably SpaceX’s Interplanetary Transport Systems. They’re intended to carry about 100 people on an intra-system journey to Mars so even they are still a very far cry from what we need — ships capable of supporting thousands of people for hundreds of years of trekking to another system.

But even if we did get our hands on a suitable ship, how will generations upon generations of humans be able to survive in a tube in space? We don’t know. All resources will have to be carefully monitored and recycled (we’re very bad at that even down here), any disease would be devastating, and we have no clue what the biological and psychological effects would be. It’s possible our colonists won’t even technically be ‘human’ when we reach our destination. Which segways into the next point: people.

Specifically, the fact that we’d have to shuttle a lot of people to have a shot at a sustainable colony. It’s not only about the risks they will face in transit or on the planet and the unavoidable deaths they will lead to — small populations would have a lot to suffer from inbreeding, so we need to ensure that a wide genetic stock is available from the get-go and can sustain itself over time. And lastly, the moral issue of who goes and who stays.

Do the rich get to go, while the poor are left to go by as well as they can/die off? Do we send our smartest? Do we send our social elites? And whom from these groups do we send? We can barely shuttle six people around. Tens, hundreds — maybe. Billions? Not a chance. Nobody will be happy to give up on the chance to survive — and yet most will have to. Good luck cracking this nut.

No planet for old habits

Dead Tree.

Image credits Colin Kinnear.

During his hour-long talk at the Oxford University Union in November, Hawking expressed his belief that humans have done a lot to hasten the end of Earth as we know it through a rampant and unsustainable exploitation of the planet’s resources. Climate change, antibiotic resistance, economic inequality, social and political unrest — anyone left behind will have to sort this mess or perish. And even if they pull it off, humanity might meet its end when an asteroid decides to pay us a visit — it happens. A lot.

He also approached the subject of artificial intelligence during the talk, where he issued some of the most explicit warnings. He said that humanity’s challenge is twofold: develop the technology that will enable us to leave the planet and start a colony elsewhere, while avoiding the frightening perils that may be unleashed by said technology. Despite the undeniable usefulness of AI, Hawking has said that it represents “our biggest existential threat.”

“Once humans develop artificial intelligence, it will take off on its own and redesign itself at an ever-increasing rate,” he warns. “Humans, who are limited by slow biological evolution, couldn’t compete and would be superseded.”

“I think the development of full artificial intelligence could spell the end of the human race,” Hawking told the BBC in a 2014 interview.


Bummer of an article, right? Well, you have to keep in mind that while the challenges we face are pretty daunting, we’re also better equipped than ever before to deal with them. We know more than ever before, and we understand the world better than we previously did. In a way, the fact that we can see the edge we’re walking to is a boon because we can at least try to stop.

But we all have to bunch together to make it happen. We’ve had a whole history to learn from. We’ve seen how good men and women, harboring the best intentions for their fellows, made horrifying atrocities possible simply by keeping silent, by not standing up for what they believe in. We’re the ones making history now, each and every one of the choices we make each day add up to shape the world.

If you don’t count asteroids, we’re not faced with an unfair fate, either — we’re mopping up after thousands of years of other people doing well or messing up. And just as we judge those before us, the textbooks schoolkids will be reading one hundred years from — regardless on which planet — will judge or praise us, remember or damn us, based on what we decide and how we live each and every day.

In Hawkins’ own words:

“However difficult life may seem, there is always something you can do and succeed at. It matters that you don’t just give up.”


“Escape our fragile planet” in the next 1,000 years or perish, Stephen Hawking says

Addressing the Oxford Union Debating Society on Monday, theoretical physics living legend Stephen Hawking issued a dire warning: humanity will probably not survive if we don’t establish viable colonies in the next thousand years.

Off I go, then! Image credits Unsplash / Pixabay.

Off I go, then!
Image credits Unsplash / Pixabay.

If you think things are looking dire right now, you might be surprised to find out that Stephen Hawking says you’re on point. It’s gotten so bad, in fact, that he says we should be on hard at working founding home-planet-B in the next 1,000 years to have any hope of survival.

“We must […] continue to go into space for the future of humanity,” Hawking said in a lecture at the University of Cambridge this week. “I don’t think we will survive another 1,000 years without escaping beyond our fragile planet.”

This isn’t the first time the professor has broached the subject of humanity’s fate. Last year, Hawking signed alongside more than 20,000 researchers and experts, including Elon Musk, Steve Wozniak, and Noam Chomsky on a letter calling for the ban of autonomous AI weapons, constructs that can use deadly force without human consent. He has also spoken out against concentration of wealth, climate change, overpopulation, and talked about the specter of pseudoscience. As Heather Saul from The Independent reports, Hawking has also estimated that viable human colonies on Mars won’t be a realistic option for another 100 years or so. In the meantime, we need to be “very careful” with the going-ons on Earth and beyond. Current troubles at home, including climate change, the rise of antibiotic-resistant plagues, and the very real threat posed by warring nations with nuclear capabilities, aren’t the full story.

Given his belief that humans seem hell-bend on repeating the mistakes of the past, Hawking says the development of “powerful autonomous weapons” is likely and will have grave consequences for humanity despite his warnings. The rise of such weapons may pit us against an enemy we don’t even understand yet, while in a precarious position. Robots are limited in what they can do today, but what happens when they equal, or even surpass us? And how can we deal with that and the effects of climate change — with shortages of land to grow crops, sinking shorelines, and spent ocean food resources — at the same time?

And then, cherry on top, an advanced alien race finds us in our desperate struggle — and decide they’re better entitled to Earth than we are.

“I am more convinced than ever that we are not alone,” Hawking says in his online film, Favourite Places.

“They will be vastly more powerful and may not see us as any more valuable than we see bacteria”.

That’s why Hawking advocates for a back-up plan. We might survive all this if there’s another place in the Solar System we can go to, a “safety planet” of sorts where we can go to lick our wounds. But the professor is still optimistic about our odds, given what we’ve accomplished so far.

“It has been a glorious time to be alive and doing research into theoretical physics”, he said. “Our picture of the universe has changed a great deal in the last 50 years and I am happy if I have made a small contribution.”

“The fact that we humans who are ourselves mere collections of fundamental particles of nature have been able to come so close to understanding the laws that are governing us and our universe is a great achievement.”

He closed his speech with a word of encouragement.

“Try to make sense of what you see, wonder about what makes the Universe exist. Be curious,” he told those attending the lecture.

“However difficult life may seem, there is always something you can do and succeed at. It matters that you don’t just give up.”

Stupidity and greed still threatens us all, said Stephen Hawking

Invited for a call by Larry King, Stephan Hawking reiterated what he had said six earlier for the same show. Hawking, the most prestigious physicist today, said air pollution has worsened, and so has global warming. All due to humanity’s greed and stupidity, which could be the end of us all.

“We certainly have not become less greedy or less stupid,” Hawking said in an interview on Larry King Now. “Six years ago, I was warning about pollution and overcrowding. They have gotten worse since then.”

Previously, Hawking warned that if humanity did not ramp up its efforts to curb global warming, the planet might end up looking more like Venus whose surface temperatures stand in excess of 250 degrees Celsius and whose atmosphere is 90 times as dense as the earth’s, mostly made of carbon dioxide.

Hawking also said a few concerning words about artificial intelligence, which he doesn’t see as ‘benign’ as everyone else.

Despite these concerns, Hawking had time to speak about some otherworldly thoughts that entertain him on a daily basis.

“What still mystifies you about the universe?” Larry King asked in a recent interview.

“Why do the universe and all the laws of nature exist? Are they necessary? In one sense they are, because otherwise we wouldn’t be here to ask the question. But is there a deeper reason?” Hawking answered.

Indeed, Hawking and colleagues at Cambridge University are very busy these days in their quest to understand the universe. At the COSMOS center at Cambridge, researchers under Hawking’s supervision are now working on the most detailed 3D map of the early universe to date. When completed, the map will plot billions of cosmic bodies from stars to black holes to supernovae.

Stephen Hawking: You Should Support Wealth Redistribution

In July, Professor Stephen Hawking took the time to answer questions posed by Reddit users in an AMA (Ask Me Antyhing), addressing one of the less discussed aspect of increasing technology and robotization: the distribution of wealth. Here’s the question, which is really interesting, and Hawking’s answer:

Q: “Have you thought about the possibility of technological unemployment, where we develop automated processes that ultimately cause large unemployment by performing jobs faster and/or cheaper than people can perform them? Some compare this thought to the thoughts of the Luddites, whose revolt was caused in part by perceived technological unemployment over 100 years ago. In particular, do you foresee a world where people work less because so much work is automated? Do you think people will always either find work or manufacture more work to be done?”


A: If machines produce everything we need, the outcome will depend on how things are distributed. Everyone can enjoy a life of luxurious leisure if the machine-produced wealth is shared, or most people can end up miserably poor if the machine-owners successfully lobby against wealth redistribution. So far, the trend seems to be toward the second option, with technology driving ever-increasing inequality.

You hear people and the media talk a lot about a potential war with robots or emerging conflicts with technology, but in my view, this is a far more pressing point. If we reach a point where machines produce all, or most of our needs, then we won’t really need so many people to work, and without work, in our current system, a huge income inequality gap will be created (or rather accentuated). With this in mind, we need to re-think our way of distributing wealth; the robots won’t be the enemy, we will.

A potential solution is a system called “basic income”, which basically revolves around the idea of offering people a sufficient sum of money every month for them to live off, whether they work or not. You can read more about it here. Several cities in the Netherlands are already starting to implement it, and Finland is considering it on a national level. There are also other ideas, but one things seems certain: the increasing use of robots and machines can either create a world where wealth is distributed harmoniously among the population, or a divided world, with very rich and very poor.

As for Professor Hawking, his entire AMA (which you can read on Reddit) was very insightful, here are another couple of Q&As related to Artificial Intelligence:

Image via Flickr.

Q: Professor Hawking- Whenever I teach AI, Machine Learning, or Intelligent Robotics, my class and I end up having what I call “The Terminator Conversation.” My point in this conversation is that the dangers from AI are overblown by media and non-understanding news, and the real danger is the same danger in any complex, less-than-fully-understood code: edge case unpredictability. In my opinion, this is different from “dangerous AI” as most people perceive it, in that the software has no motives, no sentience, and no evil morality, and is merely (ruthlessly) trying to optimize a function that we ourselves wrote and designed. Your viewpoints (and Elon Musk’s) are often presented by the media as a belief in “evil AI,” though of course that’s not what your signed letter says. Students that are aware of these reports challenge my view, and we always end up having a pretty enjoyable conversation. How would you represent your own beliefs to my class? Are our viewpoints reconcilable? Do you think my habit of discounting the layperson Terminator-style “evil AI” is naive? And finally, what morals do you think I should be reinforcing to my students interested in AI?


A: You’re right: media often misrepresent what is actually said. The real risk with AI isn’t malice but competence. A superintelligent AI will be extremely good at accomplishing its goals, and if those goals aren’t aligned with ours, we’re in trouble. You’re probably not an evil ant-hater who steps on ants out of malice, but if you’re in charge of a hydroelectric green energy project and there’s an anthill in the region to be flooded, too bad for the ants. Let’s not place humanity in the position of those ants. Please encourage your students to think not only about how to create AI, but also about how to ensure its beneficial use.


Q: Hello Doctor Hawking, thank you for doing this AMA. I am a student who has recently graduated with a degree in Artificial Intelligence and Cognitive Science. Having studied A.I., I have seen first hand the ethical issues we are having to deal with today concerning how quickly machines can learn the personal features and behaviours of people, as well as being able to identify them at frightening speeds. However, the idea of a “conscious” or actual intelligent system which could pose an existential threat to humans still seems very foreign to me, and does not seem to be something we are even close to cracking from a neurological and computational standpoint. What I wanted to ask was, in your message aimed at warning us about the threat of intelligent machines, are you talking about current developments and breakthroughs (in areas such as machine learning), or are you trying to say we should be preparing early for what will inevitably come in the distant future?


The latter. There’s no consensus among AI researchers about how long it will take to build human-level AI and beyond, so please don’t trust anyone who claims to know for sure that it will happen in your lifetime or that it won’t happen in your lifetime. When it eventually does occur, it’s likely to be either the best or worst thing ever to happen to humanity, so there’s huge value in getting it right. We should shift the goal of AI from creating pure undirected artificial intelligence to creating beneficial intelligence. It might take decades to figure out how to do this, so let’s start researching this today rather than the night before the first strong AI is switched on.

Image: The Guardian

Black holes store information as holograms at the event horizon, says Stephen Hawking

Nothing can escape a black hole, not even light, any scientists schooled in modern physics will tell you. Eminent British physicists, Stephen Hawking, suggests however that information is still retained at the boundary of black holes, known as the event horizon — an amazing new black hole fact!

Image: The Guardian

Image: The Guardian

Quantum mechanics dictates that anything – that is, matter and energy – can be broken down into information, strings of 1s and 0s for instance. A consequence of this rule is that information should never disappear, not even if the matter or energy it’s linked to is being sucked by a black hole. This hypothesis, however, contradicts Einstein’s theory of general relativity which suggests the information should be destroyed by a black hole. This is the information paradox, as physicists call it.

Hawking says that the information isn’t destroyed by a black hole because it never makes through inside. Instead, it’s trapped at the event horizon – the boundary in spacetime through which matter and light can only pass inward towards the mass of the black hole. At this boundary layer, the information is stored as a 2D hologram or super translation. A hologram is a 2D description of a 3D object.

“The idea is the super translations are a hologram of the ingoing particles,” Hawking explained.

“Thus, they contain all the information that would otherwise be lost.”

Some physicists believe we’re actually living in a holographic universe. Not that everything you see and touch isn’t real, like say in the Matrix. Rather, what we’re currently registering is a projection of a 2D Universe. Imagine watching TV – what seems like 3D objects projected on the screen are actually flat. It might sound crazy (because it’s counter-intuitive to our innate sensing abilities), but when physicists do their work assuming a 2D universe, the laws of physics make more sense. For instance, paradoxes like the information loss problem or entropy problem can be solved.

It’s not clear even that matter is being sucked by the black hole, either. The matter might also be transformed into a hologram, though there’s no consensus on this.

“Nobody really understands the details of how this happens – this is what Hawking is trying to work out and what other related ideas ‘fuzzball’ and ‘firewall’ explore too,” Prof Marika Taylor, a theoretical physicist at the University of Southampton, told BBC News.

If the information can be stored, can it be read? Theoretically, if you could tap this information somehow you would be able to reconstruct all the events that caused matter to plunge into the black hole. Think of a black hole as a paper shredder; documents are ripped to pieces and become unreadable, but if put all the paper strings together it’ll make sense. In the 1970s, the same Hawking introduced the concept of Hawking radiation – photons emitted by the black hole itself due to quantum fluctuations. Initially, Hawking thought the photons carried no meaningful information but has since changed his mind. This Hawking radiation might be a means for information to escape the black hole. The downside is that it’s in a “chaotic, useless form,” says Hawking, adding: “for all practical purposes the information is lost.”

For now, details are sketchy. Hawking and collaborators will publish a paper at the end of the month expanding on the subject.

“The message of this lecture is that black holes ain’t as black as they are painted. They are not the eternal prisons they were once thought,” Hawking said during a public lecture on Monday held in Stockholm. “Things can get out of a black hole both on the outside and possibly come out in another universe.”


Stephen Hawking doubts someone of his talent and condition would be supported today as he was

Speaking at the event that celebrated his 50th year as a fellow at the University of Cambridge’s Gonville and Caius college, Stephen Hawking expressed his doubts whether a young student of similar talents, as well as disabilities, would receive the kind of support he had. The renowned physicist, now 73 years old, has been living for the past decades with a devastating motor neurone disease that doctors believed would kill him while he was still in his early 20s. His determination to live on despite being confined to a wheel chair all his life is inspiring, but it’s unlikely he could have survived to this day were it not for his fellows and support at Caius College; nevermind his outstanding achievements in physics.


Image: The Independent

“That fellowship was a turning point in my life, as the college made sure I could continue my research, despite my increasing disability.”

Part of the college’s West Road facilities were modified to house Hawkings and his family. It’s here that he wrote his famous book, “A Brief History of Time.” In one particularly dramatic event, Hawking fell so gravely ill in Switzerland in the 1980s that doctors asked his wife, Jane, whether life support should be terminated. The college charted a plane to fly him back in the UK, while Hawking’s student and colleagues stood by his bedside during the whole ordeal.

“I was then in Addenbrookes Hospital for quite a time, unable to speak or hold anything,” he said, as reported by The Guardian.

“During that time my students participated in a rota to keep my mind occupied by reading to me, I was even able to laugh at the funny bits.”

“Caius gave me a home, literally and figuratively, and is a constant thread running through my life.”

But Hawking has serious doubts similar support would be shown to a fellow of his condition today.

“I wonder whether a young ambitious academic, with my kind of severe condition now, would find the same generosity and support in much of higher education.

“Even with the best goodwill, would the money still be there? I fear not.”

Though he didn’t elaborate, we can only speculate Hawking was referring to recent cuts in science budgets and grants in the UK.  College master, Alan Fersht, assured both the attendees and Hawking himself that these doubts aren’t well founded. But that’s speaking for his college only, not for the whole higher education system in the UK.


“Stephen questioned whether a young academic in his condition would get the same level of support today.

“For Caius at least, I can say emphatically ‘yes’. The fellowship is a family, just as our students, our staff and our alumni are all parts of the Caian family.”

He continued: “In 1965, none of us dreamt that we would be here, 50 years on, to celebrate this day. I say none, but I suspect I actually mean ‘all, but one’.”

In photo: sixteen year old inventor Arsh Shah Dilbagi demonstrating his breath to voice synthesizer.

Indian teenager invents cheap device that turns breath into speech

In photo: sixteen year old inventor  Arsh Shah Dilbagi demonstrating his breath to voice synthesizer.

In photo: sixteen year old inventor Arsh Shah Dilbagi demonstrating his breath to voice synthesizer.

About 1.4% of the world’s population today is speech impaired, due to conditions such as Amyotrophic lateral sclerosis (ALS), locked-in syndrome (LIS), Encephalopathy (SEM),Parkinson’s disease, and paralysis. Imagine all the people living in Germany today were unable to speak and you’ll come to realize just how far reaching this condition is. So, aside for those being paralyzed, there are a lot of people who can’t speak, making any kind of relationship with friends and family unbearable – the patient is essentially trapped in a situation where he/she is forced to live inside her head until the end of days. An Indian teenager sought to address this heartbreaking world problem and succeed in building a device that is easy to make, cheap and effective. Most of all, it’s extremely ingenious since it can translate orderly breaths into speech.

Follow my breath

If you followed the work of the esteemed physicist Stephen Hawking or have seen him on TV, you may have noticed that he uses a complex computer interface to speak. Oddly enough, his voice is one of the most recognized on the planet, and it’s all synthesized! The tech he employs is, however, extremely expensive.

Sixteen-year-old Arsh Shah Dilbagi took a different route. Instead of building complex and expensive IR sensors that trigger off of twitches in the cheek muscle under the eye, like those used by Hawking’s machine, Dilbagi designed a system that can translate a user’s breath into electrical signals. As such, the device is only made out of a pressure-sensitive diaphragm etched directly into a silicon chip, and an amplifying device to increase the sound of the user’s breath. This allowed him to keep the price tag at $80, compared to thousands someone would need to cash out for a device similar to Hawking’s.

The tech, called ‘TALK’, can identify two types of breaths, as well as  different intensities and timing so that the user can effectively spell out words using Morse code. An embedded microprocessor then reads the timed breaths as dots and dashes and translates them into words. A second microprocessor synthesizes the words to spell them into a voice. It’s remarkably simple and effective, even though the user needs to be trained to use Morse code, but it sure beats the alternative.

“After testing the final design with myself and friends and family, I was able to arrange a meeting with the Head of Neurology at Sir Ganga Ram Hospital, New Delhi and tested TALK (under supervision of doctor and in controlled environment) with a person suffering from SEM and Parkinson’s Disease,” Dilbagi reports. “The person was able to give two distinguishable signals using his breath and the device worked perfectly.”

Dilbagi is currently the only finalist in Asia enrolled in Google’s Global Science Fair, a competition that’s open to 13 to 18-year-olds from anywhere in the world. Let’s wish him the best of luck!


Stephen Hawking: ‘God particle’ might destroy the Universe. But wait…


Photo: Business Insider

I’m not sure what’s on with Stephen Hawking and his pessimistic view of the world. He’s been known for audacious, panic-inflicting claims like the world is going to be destroyed either by aliens or artificial intelligence, all if we don’t destroy ourselves in the meantime since humans only have 1,000 years left on this planet anyway, according to the eminent physicist. Now, it’s time for a new bold claim, one that newspapers were quick to grab onto and strap a doomsday headline.

For his new book, “Starmus”, Hawking relays some of his worries about the elusive God particle in the preface. The Professor wrote:

“The Higgs potential has the worrisome feature that it might become metastable at energies above 100bn gigaelectronvolts,” Hawking writes. “This could mean that the universe could undergo catastrophic vacuum decay, with a bubble of the true vacuum expanding at the speed of light.”

“This could happen at any time and we wouldn’t see it coming.”


The God particle, as the Higgs boson is sometimes called, is an elementary particle that is though to grant all fundamental particles mass. Despite being present everywhere and in every thing, these bosons were extremely hard to prove, but the resilience and painstaking efforts of physicists working at CERN eventually paid off when the elusive particle was confirmed to exist. This costeHawking $100 – money that he lost since he bet against the discovery of the Higgs boson.

[ALSO READ] Stephan Hawking: The Big Bang didn’t need god to happen

Ok, but now hold on there. Is Hawking actually putting gas on CERN conspiracy fires? Unlike most of the conspiracy theories that surround the Large Hadron Collider at CERN, ranging from such perils to society as birthing a black hole to building a stargate to awaken the Egyptian god Osiris, Hawiking is actually on to something. He never makes claims like these before doing his due diligence by computing. The only thing the newspapers missed is the 100bn gigaelectronvolts mark. A particle accelerator that can reach this kind of energy would have to be big enough to circle the whole planet. The Large Hadron Collider cost more than $15 billion to build and operate and it’s ‘only’ 17 miles in length.

In other news, the Stephen Hawking biopic, The Theory of Everything, will be out soon and judging from the trailer at least, it should be an interesting viewing. Anyone else excited about the movie?

Stephen Hawking brings a new perspective on what we know as black holes

This same exact statement, ‘There are no black holes’, would be clearly criticized or not even taken into consideration. But when the author of the online paper, based at the University of Cambridge, is Stephen Hawking, the entire scientific community takes the time to analyze the premises as well as the links between them. This redefinition of the cosmic crunchers comes from one of the creators of modern black-hole theory, doing away with the notion of an event horizon the imperceptible boundary believed to cloak every black hole, beyond which not even light can evade. He now calls them ‘grey holes’ and demonstrates where the pieces that didn’t fit all this time were wrong.

By countering this very commonly known theory, the physician states instead that the cosmic construction is more like a very benign ‘apparent horizon’ only temporarily holding energy and matter after which these are relieved, in a more distort form, doing away with the notion of event horizon.

While classical physics doesn’t allow matter to escape a black hole. But quantum theory ‘enables energy and information to escape the hole’, as the physicist declared for Nature, occasion with which he also admitted that an exhaustive explanation of the process would, indeed, requite a more complex theory merging gravity with other fundamental forces of nature, goal that has eluded physics for almost a century. The paper is yet to pass peer review, in attempt to solve the black-hole firewall paradox. The problem was first discovered over a couple of years ago, by Joseph Polchinski of Kavli Institute.

Concerning the definition of the concept of event horizon, this represents a mathematical consequence of Einstein’s theory of relativity, first pointed out by Karl Schwarzschild, a contemporary astronomer of the physicist in 1915. The scientific community asked themselves the thought problem of that would possibly happen if an astronomer would fall into a black hole. The unanimous answer for many years was that the subject would simply pass through the event horizon, without even realizing that, point after which he would be gradually pulled inwards. After this, his track would be commonly known – being stretched out all along towards the final point, where he would crush at the ‘singularity’ of the black hole (concept referring to the hypothetical infinitely dense core of the hole).

This is when Polchinski and his research team came to the conclusion that under the laws of quantum mechanics governing the particles on small scales the situation is completely changed – in quantum theory the event horizon is transformed into an energetic region – also metaphorically called ‘firewall’ – which would actually burn the astronaut before even getting to the inside of the hole per se. This point actually contradicts Einstein’s theory, because the subject in free fall wouldn’t just perceive the laws of physics identical with any other point in the Universe, regardless of the place or posture.

Stephen Hawking’s theory only comes to bring a third option that had not been taken into consideration so far: without denying the laws of quantum mechanism nor the general theory of relativity, he now sustains that there is no event horizon in the first place from which the astronaut could catch fire, solving this thought problem. This event horizon is, instead, replaced with the notion of ‘apparent horizon’, a covering along which any light ray attempt of rushing away and avoiding the black hole would be interrupted. Another important distinction between the two horizons is that the latter one can actually dissolve at some point. Although the paper doesn’t clearly specify the process by which this is happening, representatives from the scientific community believe this could be true, following the effects of quantum mechanics and gravity the apparent horizon should shrine and eventually disappear. At this point the matter in the black hole would be released, although in a very poor condition compared to when it was swallowed.





The Big Bang didn’t need God to happen, says Stephen Hawking @ Caltech. Also, dark matter discovery seen as most immediate goal

hawkingRenowned physicist, famous for his study of black holes, galaxies and for authoring a popular book on the origin of the universe, “A Brief History of Time”, recently arrived at Caltech, like every year, where he held a talk in front of 1,000 people who had waited in line for 12 hours to hear him speak. Hawking’s talk, as always, encompassed discussions pertaining to questions like “why are we here?” , “how did the universe came to be?” and such.

Hawking began his talk with  an African creation myth, but didn’t stray too far from his theological intro. The physicist noted, possibly in irritation, how some people seeking to find a divine solution to the creation of the Universe prefer to  counter the theories of curious physicists with poor arguments. Rather rash or not, he said “What was God doing before the divine creation? Was he preparing hell for people who asked such questions?”

As you can imagine, this stirred a few people in the audience and many more hearing about it on the web. People should have gotten used to this, however. The pope himself picked on Hawking on several occasions for his alleged disdainful claims against god. A few years ago, I wrote a piece on ZME where I also quoted some of Hawking’s answers to questions pertaining to divinity, like the afterlife. Back then, he asserted there is no heaven, nor hell, but nothingness.

How did the Universe came to be? What triggered the Big Bang? Hawking’s talk continued on with discussions relating to various creation theories some still standing, other long debunked by recent findings made possible with modern space telescopes. One of these debunked theories is  Fred Hoyle and Thomas Gold’s steady-state theory which held that there isn’t actually a head and a tail to all of this and that space bodies like galaxies, the stars that comprise them are made out of spontaneously formed matter.

Hawking also says that the Big Bang occurred at a moment of singularity, as  he and physicist Roger Penrose proved in the 1980s the universe could not “bounce” when it contracted, as had been theorized, and that most likely the Big Bang happened only once. Recent refined measurements that position the Universe’s age at roughly 13.8 billion years are on par with Hawking’s model. Still, what would be a valid theory for the Universe’s inception according to Hawking? He believes the “M-theory”, a hypothesis that is based on ideas first moved forward by lifelong Caltech lecturer Richar Feynman, as the single most valid model he has currently encountered that can explain what he has observed. In fine line, the theory – an extension to string theory – states multiple universes are formed out of nothing. Only a few are capable of creating conditions for supporting life, and even much fewer conditions for intelligent life similar to humans.

Dark matter‘s discovery, which along with dark energy combine to amount to 95% of all matter making the normal matter that can be seen and observed only 5%, is seen by Hawking as the next barrier physics needs to breach. After understanding the nature of dark matter and dark energy, many of today’s missing links could be put together and physicists may finally be able to paint an accurate picture of cosmos. Dark energy, physicists believe, would explain why the universe is expanding at an ever-growing rate instead of collapsing under its own gravity.

“There have been searches for dark matter, but so far no results,” he said. We presume, however, that he is up to date with recent reports from experiments both in space and undergrounds labs where hints suggesting the detection of dark matter have been sighted.

Hawking has been living dreadful disease – Lou Gherig’s disease – for the past 50 years which has deteriorated his motor neurons leaving him unable to move his limbs or any body part for that matter. At the time of his diagnosis he was told he would live for only two more years.

Google teams up with Stephen Hawking and launches teenage space experiment contest

Two lucky winners will have their space experiments performed in space, on the International Space Station by the astronauts stationed there.

Two lucky winners will have their space experiments performed in space, on the International Space Station by the astronauts stationed there.

The most popular video sharing website in the world, YouTube, has teamed up with NASA and several other key figures from the scientific community to launch YouTube Space Lab, a global effort challenging students between the ages of 14 and 18 to design an experiment that can be conducted in space. I know there are a lot of teenaged readers here, so this competition might be your best chance to devise an experiment trully out of this world. Read on!

Curiously enough, Google’s chairman Eric Schmidt recently criticised science and technology education in the UK, after he delivered the annual McTaggart lecture in Edinburgh, when he said the country needed to reignite children’s passion for subjects such as engineering and maths. Then came this press announcement from YouTube, which is owned by Google, publicizing this highly bold competition.

Only two winning entries will be selected from all the entries, both of which will be performed by the International Space Station astronauts. The goal is to engage students in science, engineering and math, and to help them develop their creative and analytical faculties, officials said.

“The space station really is the greatest science classroom we have,” said former astronaut Leland Melvin, associate administrator for education at NASA headquarters in Washington, D.C., in a statement. “This contest will capitalize on students’ excitement for space exploration while engaging them in real-life scientific research and experimentation.”

To enter the competition, students must submit a two-minute video application explaining their experiment, of course, on YouTube by Dec. 7. You can choose They can work alone or in groups of up to three people. Students can submit up to three experiments in one of two disciplines — biology or physics.

The winners, besides having the honour of having their experiment run in space, will get to experience weightlessness on a zero-g airplane flight, and have the option to either undergo astronaut training in Russia, or to watch the rocket launch in Japan which takes their idea into space.

The top 60 experiments will be announced on Jan. 3, 2012, at which time final judging will begin. The judge panel is quite stellar, as one might expect – renowned astrophysicist Stephen Hawking and NASA’s human exploration and operations chief, Bill Gerstenmaier, Frank De Winne, Akihiko Hoshide and noted “space tourist” Guy Laliberté.

For more information on the contest and how to enter, visit: http://www.youtube.com/SpaceLab.

Stephen Hawking

Stephen Hawking about heaven and the afterlife: “a fairy story”

Stephen Hawking

In an exclusive interview with The Guardian, the eminent British physicist Stephen Hawking shared his view upon fatality and the afterlife, sparking a wave of criticism from creationists and religious personalities as he bluntly stated that the concept of heaven is simply a “fairy story” for people who fear death.

How does Hawking explain his afterlife theory? Well, simple enough the author of the bestselling “A Brief History of Time”, which sold 9 million copies since its release in 1988, said that when the brain ceases to function, that’s it.

“I regard the brain as a computer which will stop working when its components fail,” he told the Guardian’s Ian Sample. “There is no heaven or afterlife for broken down computers; that is a fairy story for people afraid of the dark.”

Interesting enough, the most famous living physicist, currently aged 69, has been living for the past  five decades with a devastating motor neurone disease that doctors believed would kill him while he was still in his early 20s. The prospect of death, however, doesn’t preoccupy Hawing – he’s not afraid of death and this makes him a more focused individual, he says.

“I have lived with the prospect of an early death for the last 49 years. I’m not afraid of death, but I’m in no hurry to die. I have so much I want to do first,” he said.

The Guardian interview comes relatively close to another Hawking related creatioalist bashing, faithful to his statements in his 2010 released most recent book titled The Grand Design, in which he asserted that there is no need for a creator to explain the existence of the universe. The book provoked a backlash from some religious leaders, including the chief rabbi, Lord Sacks, who accused Hawking of committing an “elementary fallacy” of logic.

The interview comes just in advance of his lecture at this week’s Google Zeitgeist meeting in London, where he will address the question: “Why are we here?” At his keynote, he is expected to state his theory that tiny quantum fluctuations in the very early universe became the seeds from which galaxies, stars, and ultimately human life emerged. “Science predicts that many different kinds of universe will be spontaneously created out of nothing. It is a matter of chance which we are in,” he said.

When asked what he found most beautiful in science, Hawking said, “Science is beautiful when it makes simple explanations of phenomena or connections between different observations. Examples include the double helix in biology, and the fundamental equations of physics.”

Hawking said that our existence is down to pure chance, and that one’s goal should be to “seek the greatest value of our action.”


What’s a black hole?

Black holes are some of the most interesting and puzzling phenomena we have encountered so far; everybody has heard of them, from movies or books or whatever, but there are many misconceptions or just things most people don’t know about them, so we’re going to take a journey to the “bowels” of a black hole. I won’t get into the hardcore physics here, just explain how a black hole is formed, what it is, and other black hole facts you might find interesting.

The idea of such a thing goes from before the 1800s when geologist John Michell wrote a letter to Henry Cavendish in 1783, but it wasn’t until Albert Einstein developed his theory of general relativity that it could be (at least somewhat) understood. Black holes are the final point of the evolution of some stars; stars that are generally 10-15 times bigger than the Sun sometimes undergo a supernova explosion, which will leave behind fairly massive stellar “leftovers” that have already been burned out. Without any force to work against the gravitational pull, the remnant material will collapse on itself and the star will collapse to the point of zero volume and infinite density called singularity (since density is mass/volume) and it will create an undetectable surface which marks the event horizon or the point of no return. If something goes past that point, no matter what it is, it won’t be able to escape the gravitational pull. It is so strong, that even light cannot escape it – hence the term black hole.

This property makes it invisible to the eye, but it can be studied by analyzing the way it interacts with other matter, especially from a gravitational point of view – which requires a quick word about gravity. From the classic or Newtonian point of view, gravity is a force in which two bodies with mass attract each other. However, from Einstein’s modern relativistic point of view, gravitation is described as an effect of the spacetime curvature instead of a force, a curvature caused by the mass of the bodies. So gravity and time are bound together – if we were to measure time closer to a black hole, we would find that time would pass much slower, and if you were to measure time in the center of the black hole, you would find it would not pass at all.

As I explained above, in the center of the black hole there lies a gravitational singularity, a region where the spacetime curvature becomes infinite. That region can be thought of as zero volume and infinite density. Anything that falls into the singularity will be ripped apart and its mass will be added to that of the black hole. But a black hole isn’t a demonic vacuum cleaner that slowly sucks anything and everything, no matter the distance. If for example, we were to replace the Sun with a black hole of exactly the same mass, the Earth, as well as the whole Solar System would move exactly the same; for an outside observer, this would be pretty funny, seeing a whole solar system revolve around… nothing (nothing visible, that is). If we were to speak about temperatures, it would be an entirely different problem, but the gravitational effect would be the same, despite the black hole having a radius of only a few tens of kilometers.

The closest black hole from us is no less than 1.000 years away, so we probably don’t have anything to worry about, but then again, at the center of our galaxy, the Milky Way, there is a supermassive black hole with a mass of 4,000,000 times bigger than the Sun. There is good reason to believe that these supermassive black holes are at the center of most, if not all, galaxies, and it’s estimated that they can have a mass a few billion times bigger than that of the Sun. Also, black holes do grow, basically sucking anything they can around them, and making things they cannot suck revolve around them.

In 1970, British researchers Stephen Hawking and Roger Penrose realized that black holes and the Big Bang have very much in common. Inside the black hole, there is a point of infinite curvature, which is presumably what the Universe looked like before the Big Bang, so the process of a star collapsing into a black hole is just like the Big Bang in reverse. The details surrounding this matter, however, become quite fuzzy. General relativity does explain how things work when space is curved but doesn’t explain how it works when infinitely curved. Since we are talking about an indefinitely small space, the laws of quantum mechanics should be considered too, but our current understanding of quantum mechanics doesn’t work in space that is curved, let alone space that is infinitely curved. So from this point of view, quantum mechanics and general relativity are inconsistent with each other, which is just one of the reasons why studying black holes is important. Both theories predict something different will happen, given a set of conditions, so if we were to somehow find what would happen, this will show us the correct theory to apply. If we were to put it this way, quantum mechanics and general relativity are the key players in a team. But sometimes they just don’t work together at all, so there is a need for another theory to reconcile the two and smoothen things up – for example, string theory.

To make things even harder to study, black holes may also be rotating, and/or electrically charged. There are only three properties that can characterize a black hole:

  • mass, the most important parameter
  • angular momentum
  • electric charge

An interesting fact is that mathematically speaking, any general relativity equation solution is symmetric in time, basically, take any solution and imagine another solution that works as the first one, but with time in reverse. If you apply this to black holes, you will get what is a white hole, and object you can not enter, and that can only spit things out. This is a good example of why mathematical solutions cannot exist in nature; if we define a white hole as the temporal opposite of a black hole, then the process of creating a white hole is the same as the process of destroying a black hole – which is impossible.

Picture sources: 1 2 3 4