Category: stephen hawking

Sorry, Stephen Hawking, But Every Black Hole Is Still Growing, Not Decaying

“It remains true that every black hole that exists in the Universe should emit Hawking radiation, and that if you wait long enough, all of these black holes will eventually decay. But in our Universe so far, based on the black holes that actually exist, not a single black hole has even begun to decay in a meaningful way. The amount and energy of the radiation that’s out there, from starlight and left over from the Big Bang, ensures that black holes will absorb it and grow much more quickly than they lose energy from radiating it away.

Even though it’s been more than 45 years since Hawking first figured out that black holes do emit radiation, as well as what that radiation must look like, it’s far too faint and sparse for us to have ever detected it. Unless there’s a surprisingly low-mass black hole or we’re willing to wait an enormous, cosmic time for the Universe to cool, we’ll never be able to see it. Black holes are growing, not decays, and astrophysics teaches us exactly why.”

Yes, black holes emit radiation of exactly the type described by Stephen Hawking: a low-energy spectrum of photons and other particles arising from the physics of quantum field theory in curved spacetime. But, for much longer, we’ve known that black holes must also be absorbing energy over time, from matter, from starlight, and from the cosmic microwave background radiation.

The results are in, and every realistic black hole in the Universe is growing, not decaying, and it isn’t even close.

Ask Ethan: Why Is The Black Hole Information Loss Paradox A Problem?

“Why do physicists all seem to agree that the information loss paradox is a real problem? It seems to depend on determinism, which seems incompatible with QM.”

There are a few puzzles in the Universe that we don’t yet know the answer to, and they almost certainly are the harbingers of the next great advances. Solving the mysteries of why there’s more matter than antimatter, what dark matter and dark energy are, or why the fundamental particles have the masses they do will surely bring physics to the next level when we figure them out. One much less obvious puzzle, though, is the black hole information loss paradox. It’s true that we don’t yet have a theory of quantum gravity, but we don’t need one to see why this is a problem. When matter falls into a black hole, something ought to happen to keep it from simply losing its information; entropy must not go down. Similarly, when black holes evaporate, a la Hawking radiation, that information can’t just disappear, either.

So where does it go? Are we poised to violate the second law of thermodynamics? Come find out what the black hole information paradox is all about, and why it compels us to find a solution!

Student 1: Didn’t Stephen Hawking get disabled from jumping off a building?

Student 2: No, he has some disease.

Student 1: Oh, I thought he threw himself off a building or something.

Student 2: Why?

Student 1: It made him smarter didn’t it? Like when blind people have other senses get better because they can’t see anymore? It made him smarter because he can’t talk or walk anymore.

The Black Hole Information Paradox, Stephen Hawking’s Greatest Puzzle, Is Still Unsolved

“Despite our best efforts, we still don’t understand whether information leaks out of a black hole when it radiates energy (and mass) away. If it does leak information away, it’s unclear how that information is leaked out, and when or where Hawking’s original calculations break down. Hawking himself, despite conceding the argument more than a decade ago, continued to actively publish on the topic, often declaring that he had finally solved the paradox. But the paradox remains unresolved, without a clear solution. Perhaps that’s the greatest legacy one can hope to achieve in science: to uncover a new problem so complex that it will take multiple generations to arrive at the solution. In this particular case, most everyone agrees on what the solution ought to look like, but nobody knows how to get there. Until we do, it will remain just another part of Hawking’s incomparable, enigmatic gifts that he shared with the world.”

When anything falls into a black hole, it adds to the black hole’s mass, electric charge, and angular momentum, which is what General Relativity predicts. But there’s also quantum information encoded in what falls in, and that information can’t be destroyed. There’s a neat solution for that: information can be encoded on the event horizon of a black hole, getting “smeared out” from the perspective of an outside observer. But then, what happens to this information when the black hole evaporates via Hawking radiation? Hawking himself predicted that information was lost, which is now thought to be wrong. But the question of exactly how that information gets encoded onto the outgoing radiation is still a matter of massive uncertainty. Despite declarations by many (including Hawking) that the paradox has been resolved, the fact is that the black hole information paradox is still an open area of study.

Come find out what the greatest problem in black hole physics, the one that plagued Hawking all his life (and continues to plague him even posthumously) is all about!

I Am An Astrophysicist. Here’s What Stephen Hawking’s Final Paper Was Actually About

“The questions that they’re attempting to answer are still valid, open questions, and the best this paper can do — if it’s correct and relevant, and it may be neither — is provide suggestions towards an answer. The approach is largely based off of work that Hartle, Hawking, and Hertog have done in the past, the dS/CFT connection pioneered by Chris Hull and others, along with string-inspired work done by Andrew Strominger and his collaborators. None of this is based off of any realistic cosmological models; these are toy models that they are calculating in, and then reasoning-by-analogy with what we actually know exists. Like most theoretical work in the very early stages, there are interesting ideas that are presented, the work and calculations are highly speculative, and there is not necessarily a connection with reality. But there’s a non-zero chance that one is real. And in theoretical physics, a novel idea with a chance is worth infinitely more than no new ideas at all.”

There have been a lot of incredible claims floating around the media about what’s going on with Stephen Hawking’s final paper, which was submitted earlier in March, less than two weeks before he died. Some are claiming it will help us detect the multiverse, others claiming that it will tell us how the Universe will end. The truth is much more sobering, however: it discusses issues involving the dynamics of inflation. There are incredible questions we’re trying to understand about the Universe, such as: did inflation begin, or was it eternal; will it continue indefinitely into the future; does it inevitably lead to a multiverse; did time and space begin with a singularity? These are very important, and Hawking’s final paper was the construction of a toy model that argued “yes” for the final question. But it has nothing to do with the hype surrounding it.

Let’s not deify our heroes; let’s allow their good work to stand on their own merits. And most importantly, let’s be honest about what they did. Here’s the truth.

How Stephen Hawking’s Greatest Discovery Revolutionized Black Holes

“Increasing entropy, over time, should be okay, but decreasing it should be forbidden. The only way to ensure that would be by forcing an increase in the black hole’s mass to cause entropy to go up by at least the largest amount you can imagine.

The way that people working on that problem – including Hawking – assigned an answer was to make entropy proportional to the surface area of a black hole. The more quantum bits of information you can fit on a black hole, the greater its entropy was. But that brought up a new problem: if you have entropy, then that means you have a temperature. And if you have a temperature, you have to radiate energy away. Originally called “black” because nothing, not even light, can escape, now it became clear it had to emit something after all. All of a sudden, a black hole isn’t a static system anymore; it’s one that changes over time.”

Stephen Hawking may be most famous, today, for his popular accounts of astrophysics and cosmology, for his inspirational personal story, and for his overcoming of adversity and disability to achieve all that he has. But he was truly a tremendous physicist, and his contributions to our understand of black holes was truly transformative. His greatest discovery was that they weren’t merely static objects in space, but that they were active and evolving. They didn’t just absorb mass, but had an entropy, a temperature, and radiated energy away. How this occurred was far from intuitive, and it took a decade of research for Hawking to arrive at his incredible 1974 result, where he derived the existence of Hawking radiation. All of a sudden, black holes had a finite lifetime, and would eventually evaporate away entirely.

Here’s the story of Stephen Hawking’s greatest scientific find, and his greatest contribution to the canon of scientific knowledge. If you want to understand what he did and why it’s so important, you won’t want to miss this.

The 4 Scientific Lessons Stephen Hawking Never Learned

“His work, his life, and his scientific contributions made him an inspiration to millions across the world, including to me. But the combination of his achievements and his affliction with ALS — combined with his meteoric fame — often made him immune to justified criticism. As a result, he spent decades making false, outdated, or misleading claims to the general population that permanently harmed the public understanding of science. He claimed to have solutions to problems that fell apart on a cursory glance; he proclaimed doomsday for humanity repeatedly with no evidence to back such claims up; he ignored the good work done by others in his own field. Despite his incredible successes in a number of arenas, there are some major scientific lessons he never learned. Here’s your chance to learn them now.”

Hawking’s contribution to physics, from the existence and meaning of singularities to properties of a black hole’s event horizon, entropy, temperature, and the radiation they generate were remarkable in the 1960s and 1970s. His popularizations of science were groundbreaking, too, exposing a general audience to a wide variety of wild and speculative ideas, igniting an interest in theoretical astrophysics in the minds of millions around the world. But as brilliant as Hawking was, there were a number of lessons about science and humanity that he never learned for himself, from the Big Bang and black holes to lessons about communicating speculative or unproven information as though they were facts. We have a tendency, when we turn people into heroes, to lionize their achievements and ignore their failings, but to do so cheats humanity out of recognizing all the facets of a complicated character.

Come learn, for yourself, the 4 scientific ideas that Stephen Hawking never managed to learn and incorporate while he was still alive.

Have a nice Pi-Day! In memory of Stephen Hawking!

March 14,2018 (03/14/2018)

** Einstein was born, Hawking passes away and it’s pi day…

Stephen Hawking: modern cosmology’s brightest star dies aged 76:

“One, remember to look up at the stars and not down at your feet.

never give up work. Work gives you meaning and purpose, and life is
empty without it.

Three, if you are lucky enough to find love, remember
it is there and don’t throw it away.” – SH

RIP Stephen Hawking. We will miss you for ever.