Episode 125 - The Black Hole Conspiracy
Recap: Black holes seem like a given in popular culture: They exist, they have to, right? Well, some people claim they don't. In this episode, we go through the theoretical underpinnings for black holes, some of the observational evidence for their existence, and examine some of the claims made by credentialed and practicing physicists who state that black holes cannot exist.
Q&A: This episode's question comes from Mark from Canada who asks: “Since Black Holes can lose mass through Hawking Radiation, is it possible for them to lose sufficient mass to no longer be a Black Hole, and become, say, a Neutron Star?”
The short answer is, “no.” While black holes can theoretically lose mass as Mark stated, by Hawking Radiation that gets into weird properties of quantum mechanics, what makes a black hole be a black hole is its density. The idea is that once you’ve compressed something beyond what had stopped it from compressing before - once you’ve changed the very nature of the material making it up, so far as we know, it’s not going to spring back into what it was before.
Which, now that I think of it, is a good analogy: A spring. With a classic spring, you can stretch or compress it to a certain degree, and it will always come back. That’s like normal matter in this analogy. But, now stretch it so that the spring is straight. It’s never going back to a spring shape. That’s like a black hole. Even if you try to push it to go back to a spring, like removing mass from a black hole by Hawking radiation, it’s never going to go back to a spring.
- Mike Bara's review of "Interstellar"
- Wikipedia on: Black Holes || Sagittarius A* || S2 || Kepler's Laws of Planetary Motion || Accretion Disk || Hawking Radiation
- Astronomy StackExchange: How Are Black Holes Found?
- How GPS Relies on Special and General Relativity
- Phys.org: "Researcher Shows that Black Holes Do Not Exist"
- Daily TarHeel: "Experts Skeptical About Black Hole Research"
- RT: "No Black Holes? Scientist Claims Mathematical Proof"
- Independent.co.uk: "Stephen Hawking: 'There Are No Black Holes'"
- Ghez, A. M.; et al. (December 2008). "Measuring Distance and Properties of the Milky Way's Central Supermassive Black Hole with Stellar Orbits". Astrophysical Journal 689 (2): 1044–1062. arXiv:0808.2870. Bibcode:2008ApJ...689.1044G. doi:10.1086/592738.
- Gillessen, Stefan; et al. (23 February 2009). "Monitoring stellar orbits around the Massive Black Hole in the Galactic Center". The Astrophysical Journal 692 (2): 1075–1109. Bibcode:2009ApJ...692.1075G. doi:10.1088/0004-637X/692/2/1075.
- Logical Fallacies / Critical Thinking Terms addressed in this episode: Argument from incredulity, argument from ridicule, Burden of Proof, Ad hominem, straw man, argument from authority
- Relevant Posts on my "Exposing PseudoAstronomy" Blog
Claim: The specific claim for this episode is a simple one: Black holes don’t exist. You might think that this is a crazy claim only made in the fringes of the internet, but at least once a year or so, I also see the same claim made by a real, otherwise mainstream physicist. So, let’s look at some of the arguments made against them, and let’s look at some of the arguments for them.
Mike Bara’s Claims
I first got the idea for this episode when I was browsing through Mike Bara’s review of the movie “Interstellar,” from a few months ago. When I saw this line, I was shaking my head sadly: “Black holes of course, are a lot different than wormholes, because everybody knows they exist, right? Well... Not really.”
Mike actually brings up several points that I had thought about for this episode, so it’s worth quoting him and then going back to examine each one. First, there’s this:
"A new paper by Laura Mersini-Houghton, a physics professor at UNC-Chapel Hill College of Arts and Sciences, concludes that not only to event horizons not exist, black holes don't exist either. Confronted with this new information, even Stephen Hawking has now concluded that his entire life's work, the study black holes, may have been in vain."
So the basic idea there is that a physicist says they don’t exist, and now even apparently Stephen Hawking seems to be jumping ship. Definitely worth looking into.
Then there’s this:
"And there's one other issue. Like the wormhole, no one has ever observed a black hole. Even NASA's own website on black holes has this to say about them: "Because no light can get out, people can't see black holes. They are invisible." Kind of like "Dark Matter." Scientists are sure they exist, but have never seen one and probably never will. Maybe they should just rename black holes "Unicorns.""
This is two logical fallacies wrapped up into an argument: Argument from Incredulity, and Burden of Proof. I’ll discuss those after the main segment, they’re not worth talking about in the main one other than when talking about this next quote:
“But the mainstream guys, who get paid to write papers about this stuff (I wish I did) argue that while we will never observe a black hole, we "know" they exist because we can see all the light and energy they emit. Huh? I thought nothing could escape from a black hole, and now they emit light and energy? My caveman brain is confused[…]”
I would point out that Mike is paid to write and talk about a whole lot of stuff that most people don’t believe in, and just make things up as he goes, so I wouldn’t be complaining if I were him about scientists who have to spend weeks writing grants that have a 5-15% of being funded and then have to do work and make sure that it makes sense with everything else we know about the universe and then spend around 200 hours to write it up and make it through peer review. But my own little rant aside, this point about being able to see light and energy from a black hole is a common misconception that is worth getting into, as well.
Mike then goes into a few of the cited evidences for black holes that I’ll also get into, but he explains them away as, (1) it could be something else, (2) read my book where I totally blew away mainstream science and showed that there’s another force that makes all these effects happen, and (3) all the scientists are wrong even though their observations may be right.
There’s also this:
"The simple fact is that black holes, wormholes, time dilation and curved space exist only on paper. There is in fact no observational evidence of their existence. In fact, many of the observed effects cited to support their existence often have perfectly viable alternative explanations that make far more sense. But to admit that would be to admit that their precious equations may be wrong, and that is a place that mainstream cosmologists just can't go. But the simple truth is, no matter how many degrees Kip Thorne or science choad Neil throw around, no matter how many times the media calls their work or the film 'hard science," it isn't. It isn't science at all, because NONE of it is testable, or even based on observation.
"You can no more find truth in a mathematical equation than you can hear a beautiful melody by reading musical notation. Science is observation, experimentation, measurement and insight. It isn't numbers on chalk board.
"It is possible that black holes, worm holes, time dilation and the curvature of space exist. I'm just arguing that no proof of any of them exists today."
Besides again invoking the Burden of Proof (along with an ad hominem thrown in, which is common in Mike Bara’s writing), Mike’s last few sentences here clearly indicate that he does not understand how science works. As such, I’m going to start getting into this topic by discussing that very thing.
How Science Works
If you could try to summarize everything about science into perhaps one over-riding goal, it is to understand how everything works. We do this by developing hypotheses for how something works, and then designing tests of those hypotheses. If the test cannot falsify that hypothesis, we come up with another one. Eventually, if the hypothesis has withstood all attempts to disprove it, it becomes a theory, the pinnacle of a scientific idea.
But, a theory doesn’t necessarily have explaining power. And, inherently, it is still a model of what is going on. But it is a very powerful model because that theory can be used to make predictions. Newton’s theory of gravity is used to predict how an unpowered, unguided missile will behave. For the simple act of playing any sport that involves a ball, your brain has developed its own theories of how things work, with gravity, wind, your strength, properties of materials that the ball may run into, and so on. Your brain represents them as neural pathways and chemical methods of storage. Scientists use equations.
Therefore, when Mike states, “You can no more find truth in a mathematical equation than you can hear a beautiful melody by reading musical notation. Science is observation, experimentation, measurement and insight.” … he is exactly correct in his second sentence, but he is exactly wrong in his first. They are NOT mutually exclusive, so long as by using the word “truth” you are not talking about the metaphysical “truth” that is unattainable (in which case we’re making a straw man because science can’t do that), but rather “truth” as in, “the ability to make models that precisely predict how things will behave.”
And so, that’s how science works. With that in mind - that we want to create a model, test that model, and then make predictions using it, we can turn our attention to black holes.
Black Holes: Idea
One of those predictions is what should happen if an object is very massive. Well, to escape from it, you have to move faster. That’s why it’s easier to get off the Moon than it is Earth. That’s why if we could launch missions that are already in Earth orbit, it would take a lot less fuel.
But, what happens if you have the same mass, but shrink the object in size. Well, as you get closer to the center of mass, you have to move faster to get away. And, you get to a point where the mass is concentrated in an object so tiny, that the escape velocity is now faster than the speed of light.
In a nutshell, that’s what a black hole is: An object so dense - because it has so much matter packed into such a small space - that the escape velocity is faster than light. Now, there are entire college courses taught about black holes, so I am very much glossing over every single detail here, but explaining how black holes form and more about their theoretical properties is beyond the purpose of this episode.
Being an episode about black holes, I have to talk about both special and general relativity, at least a little. The idea behind special relativity is that the faster an object moves relative to another, the slower time passes for it. That doesn’t have much to do with black holes, but it becomes important for some of the observations that are made of stuff around them.
General Relativity is what is more important in the discussion of black holes, but it is more how they form, how we observe their effects, and how they were thought of in the scientific community than understanding the basic idea: That a black hole is an object so dense that light can’t escape it.
The modern concept of the black hole came out of solutions to Einstein’s Relativity equations which showed what would happen if you try to describe the gravity of a point mass — that is, an object that has collapsed in on itself so much that it has literally zero dimensions, it only has mass.
After nearly two decades and many physicists working on the problem and publishing papers, the modern idea of the black hole was effectively born, which is an object, such as a star more than three times the mass of the sun, that is so massive that nothing can stop it from collapsing in on itself. As it collapses into that theoretical point object, it becomes small to the point where its surface is now smaller than where the escape velocity is the speed of light. That surface is then termed the “event horizon,” because an object would need to travel faster than light to escape it, and we don’t know of anything that can, we can’t know what goes on inside of it.
But this is not a physical boundary. It’s just one that’s defined on the scale of increasing escape velocity as you get closer and closer to the center of mass. As far as Relativity and other relevant physics predicts, the mass in the middle continues to collapse in on itself to a point of no dimension and infinite density, or a quantum singularity, or who knows what.
The problem is that, as the humorous t-shirt puts it, “Black Holes are where God divided by zero.” We have a lot of theoretical physics that predicts what should happen as you get there, and what goes on as the object collapses. But we don’t have a physics to predict what happens to that original object because our equations, in some cases, are quite literally being divided by zero. We need a new physics that merges Relativity and Quantum Mechanics to predict it.
But, all because the theories are INCOMPLETE does not mean they are wrong. And, there is a lot of evidence for black holes as well as relativity.
And, because of the issue of Burden of Proof being raised with respect to black holes and much of theoretical physics, I think an aside is needed for evidence of relativity. Both general and special relativity are scientific theories. There have been literally hundreds if not thousands of separate, independent observational tests for both over the last century, each one stressing more and more of the model’s predictions. Every single one has been in line with the predictions of Relativity to within the measurement errors.
As a simple, every-day example that most everyone has some experience with, GPS. GPS positioning would not be nearly as accurate as it is if it did not factor in relativity’s effects because of the mass of Earth versus where the satellites are in space.
What do I mean? Well, GPS works by knowing exactly where satellites are, and exactly what time it is on them. If I am on the ground and I have a signal from at least three satellites, and I know what time it was sent, and I know how far away each satellite is from me, then I can tell you based on the difference in arrival time where I am. For example, with just one satellite, based on the time on the satellite and the time it arrived to my clock, I know how far I am from that satellite based on the speed of light. If I have two, then I can start to get an idea of where I am in 2D space. Add a third, and I get where I am in 3D space. Add a bunch of others, and the uncertainties in each measurement combine to give me a more accurate and more precise result.
But, the only way that level of accuracy can be had is if I know the clock’s time on the GPS accurately. To get a few meter precision, that’s 20-30 nanoseconds, or one part in 1^-8 seconds. That’s only possible if you also factor in Special and General Relativity. Special Relativity is important because the satellites are moving relative to me. Therefore, their clocks move more slowly by about 7 µs per day due to time dilation.
General Relativity factors in because the satellites are high above Earth, farther from the center of mass than we are on the ground, and so time moves more quickly for them than it does for us, trapped farther within Earth’s gravity well. The predicted effects are that the satellites’ clocks should tick faster by about 45 µs per day. Add the two up, remembering the positive and negative signs, and that’s a net of 38 µs per day.
That’s a factor of 1000x larger than our required accuracy for GPS clocks, so if either Relativity theory were wrong, this would quickly prove itself out in GPSs being horribly off after even a few days, at a rate of about 10 km per day. A few meter accuracy would fail within a few minutes. Mike Bara claims that all this shows is that mechanical clocks (even though these aren’t mechanical) move more slowly, and doesn’t prove time dilation.
But, there is a lot more evidence for both Relativities beyond what I just gave as a single example. Hundreds. So at this point, both are certainly theories, and therefore we can continue to use their predictions of what should happen under various circumstances.
Black Holes: Observational Evidence of Their Effects
Embedded within all of that previous discussion is the theoretical evidence for black holes. They naturally come out of the theories that otherwise have been shown to accurately model the universe. But what observational evidence is there?
Several different lines of observational evidence for their EFFECTS. I’m going to discuss two.
First is the motion of stars around the center of our own galaxy. The center of our galaxy is called simply, Sagittarius A*. That’s because it’s in the constellation Sagittarius, and it is a massive x-ray source that is part of the larger astronomical feature known as Sagittarius A. It is thought to be a massive black hole of the mass of about 4 MILLION times the mass of our sun.
A couple reasons, but the one I’m going to talk about is stellar orbits. We have literally, over the last two decades, watched stars complete orbits around the center of the galaxy. One of them, known simply as “S2,” orbits Sgr A* in about 15.5 years. We also know how far away it is, about 8 kpc, or 26,000 light-years, so we know that it is on an orbit around Sgr A* that is characterized as around 120 AU, or 17 light-hours. Knowing its period and knowing its orbital distance, we can go back to the primary sponsor of this show, Johannes Kepler and his Third Law of Planetary Motion to give you the mass of the object that it’s orbiting.
What I love about this stuff is that it’s so basic. Yeah, you need a good telescope and several years to make these observations, and math that was developed four centuries ago, but it’s incredibly hard to argue with them because claiming they are wrong would mean that so much other stuff is wrong.
So we have the mass of Sgr A*. 4 MILLION solar masses. And, all of that mass MUST be contained well within 120 AU because that’s the size of S2’s orbit. The only object that we know of that could possibly explain this is a black hole, for it’s the only thing that could both be that small and that massive, and as an added bonus, not emit any light.
Oh wait, didn’t I say it is a strong radio source? And didn’t Mike point out that people say that black holes emit all this high-energy radiation but people also say that not even light can escape?
That brings us to the second piece of observational evidence of their effects that I’m going to discuss - rather than an inconsistency or refutation - and that’s the material coming from AROUND the black hole.
As I said, the black hole’s size is in part characterized by the event horizon. Nothing we know of can escape it other than the Tardis. But, that doesn’t mean stuff immediately outside of the event horizon can’t escape, including light. In fact, by definition, it can. If a black hole formed from a star, or even a bunch of stars as the ones in the centers of galaxies are thought to have formed, or at least grown from, then the Law of Conservation of Angular Momentum means that it’s going to spin. Very, very fast. And another prediction of relativity that has been shown to be true is that it will drag space-time with it.
This causes material to follow a tendex line, or a spiral, into the black hole past the event horizon. In other words, stuff being dragged into the black hole is going to spin along with the black hole, and just like most other material around other objects in the universe - be it trans-Neptunian objects, planets, forming stars, black holes, or galaxies - the material flattens into a disk.
And we have imaged these disks.
As the material is drawn in, the intense gravitational stretching and just all the material colliding that, in part, causes it to form a disk in the first place, is converted heat. Just like if you rub your hands very fast against each other in opposite directions, you generate heat. In the disks around black holes, the material gets so hot that it glows very brightly and generates light of all wavelengths, including radio that I mentioned for Sgr A*, but also stuff like x-rays. Estimates are that 10—40% of the material orbiting a black hole may be converted into energy, emitted as light, before it ever moves past the event horizon.
And so, when we observe these intensely bright objects, and the brightness is coming from such a very, very small object, the only object that we know of in astrophysics that could possibly account for this is an accretion disk around a black hole.
Is it possible that it’s not a black hole, and that it’s something else that we have not discovered? Sure. But we already have a theoretical object that is predicted that can account for this observation. So until there’s evidence against it, or for a quote-unquote “better” kind of object to explain it, there’s no reason to not think it’s a black hole.
So, those are two methods of looking at the effects on objects that are predicted by black holes to show that black holes likely exist. No other known object can explain them or other, related phenomena.
So what’s up with physicists (real ones that have a scientific background and credibility) claiming that black holes don’t exist? The latest example is by Laura Mersini-Houghton, with co-author Harald Pheiffer. The basic argument is this:
(1) Stephen Hawking in 1974 posited that black holes can emit radiation (now known as Hawking Radiation) and very very slowly evaporate. Why is beyond the scope of this episode, but we actually have made observations that are consistent with Hawking radiation, so it’s fairly well accepted now.
(2) Dr. Mersini-Houghton and Dr. Pfeiffer used Hawking Radiation with a stellar collapse in a simulation and from that simulation found that the star emits so much Hawking Radiation as it collapses that it loses too much mass and it can never reach the critical point to collapse into a black hole. That’s about as much as I can simplify it.
So, is she right? This is where we get into the process of science. The two authors submitted their paper to arXiv.org, which is an online NON-PEER-REVIEWED repository that ANYONE can submit to. There is no indication that this has been submitted to a journal for peer-review, though it likely has. But for some reason, there is already a press release out about it and sensationalistic headlines have made the rounds stating things such as, “New study claims black holes are mathematically impossible.” (That’s the one that Mike Bara linked to.)
Since this is far beyond my area of expertise, I look to what the experts are saying. You might call out that that’s an argument from authority on my part, but remember that the entire story is based on two people, so that’s just as much if not more of an argument from authority than me looking to see what others have said.
And, they have not been kind to the idea. For example, Dr. Pretorius of Princeton stated, “My first impression was that the model they used for the quantum effects was dubious at best, and this is the crucial part to allow them to conclude black holes won’t form. If my concerns are justified, my suspicion is there could be substantive changes to the paper through the refereeing process.” That’s a kind way of saying that the reviewers may correct the math and show that the entire paper is wrong.
Dr. Unruh who’s a theoretical physicist from University of British Columbia put it more plainly: “The [paper] is nonsense. Attempts like this to show that black holes never form have a very long history, and this is only the latest. They all misunderstand Hawking radiation, and assume that matter behaves in ways that are completely implausible. … Unfortunately, explicit calculations of the energy density near the horizon show it is really, really small instead of being large. Those calculations were already done in the 1970s. To call a bad speculation ‘has been proven mathematically’ is, shall we say, an overstatement.”
In addition to all of that, if you’re going to claim that black holes don’t exist, you need to provide a counter explanation for all the evidence that we have of them. The authors don’t do this, and don’t even appear to have tried to do this.
As I said earlier though, I’m not an expert in this particular field. But it looks dubious, based on what the experts in that field are saying, that this is not going to bear out in the long run. Just as all the other attempts to disprove black holes have over the years.
But, what about Stephen Hawking. After all, a year ago - January 2014 - news outlets around the world crowed that Stephen Hawking stated, “There are no black holes.”
Unfortunately, this is a case where the soundbite headline belies the story. At issue is what exactly goes on at the event horizon of a black hole. And, more to the point, can a black hole, because of what we know and don’t know about the laws of physics, even have an event horizon? I mentioned earlier that this is a place where God divided by zero.
Similarly, our models for how things work have a hard time predicting what occurs at a quantum level - and when I say quantum, I actually mean quantum: What’s going on with the very nature of matter on not only atomic scales, but those smaller than atoms. And, what is the nature of the space-time in which those processes are occurring.
The classic idea of an event horizon holds up, at least as far as we can observe the effects of matter close to it. But, that could be just like Newton’s laws of gravity predict very accurately how things behave in our everyday experience, but when you stress them out, like pass light very near the sun, they break down, and you need something different, like Relativity.
Similarly, what happens right near the event horizon at a very large scale is something that our predictive models can explain so far as we can observe them. But what happens at the smaller scales, maybe not. What Dr. Hawking’s work showed a year ago is that what might be going on at a quantum level at the event horizon of a black hole may mean that it doesn’t have an event horizon in the classic sense. There might still be ways for energy or light to escape via the weird laws of quantum mechanics. It needs a lot more theoretical work, but it’s possible, though how we could test it remains elusive.
But, that’s also where the soundbite came from. Stephen Hawking stated, “The absence of event horizons means that there are no black holes - in the sense of regimes from which light can’t escape to infinity. … There is no escape from a black hole in classical theory, [but quantum theory] enables energy and information to escape from a black hole.” Which is very similar to Hawking radiation that he developed 40 years ago.
So, for a wrap-up, where are we after all of that exposition? People claim black holes don’t exist. Most scientists claim they do. The evidence for them is based on how they are predicted to affect material around them, and those have born out. Just as I can’t see wind, I can feel and see its effects.
To say that they don’t exist requires more than just a blanket statement. It requires showing why the predictions of relativity are wrong and explaining what else could cause the phenomena that are seen and attributed to black holes. Without doing that, it holds as much weight as me saying that the center of the moon doesn’t exist because nobody’s seen it. But, a Hollow Moon episode will have to wait for another time.
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David Roberts Tropic UT USA
10:34pm on Sunday, March 22nd, 2015
I never heard of Mike Bara until this show. Should I thank you? As near as I can tell, the only discipline he excels in is cliche.Right down to the colors on his book covers. I can't say much for his grammar either. But ignore my ad hominem examples and lets go straight to the facts. Opps, there aren't any.