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Beyond the infinity of black holes

As noted previously, quantum physics has struggled with infinities. A recent Space.com article on black holes reminded me of another part of that saga. Black holes serve as touchstones in several ways.

Wiki: … there are some theoretical circumstances where the end result is infinity. One example is the singularity in the description of black holes.

First, it’s amazing that we’re talking about black holes at all. It wasn’t long ago — maybe a 100 years or so, that our view of the cosmos was much more circumscribed. Those who studied cosmology — physicists, astronomers, et al, viewed our cosmos in a much different way, at a much different scale — basically an island universe: Earth, the solar system and the Milky Way. We existed in a galaxy, but a singular one.

Now, almost one hundred years later, it is difficult to fully appreciate how much our picture of the universe has changed in the span of a single human lifetime. As far as the scientific community in 1917 was concerned, the universe was static and eternal, and consisted of a single galaxy, our Milky Way, surrounded by a vast, infinite, dark, and empty space. This is, after all, what you would guess by looking up at the night sky with your eyes, or with a small telescope, and at the time there was little reason to suspect otherwise. — Krauss, Lawrence. A Universe from Nothing: Why There Is Something Rather than Nothing (pp. 1-2). Atria Books. Kindle Edition.

The radical change in cosmic perspective has consequences. Certainly in origin theories. But also regarding philosophies which predate modern knowledge. The situation goes beyond just a revisionist approach to the “God of the gaps” argument. As Lawrence Krause points out:

Science is compatible with some basic form of deism … But having said that, science is not compatible with all the strict doctrines of all the world’s major religions, and that includes Christianity, Judaism, Islam, as well as some of the minor ones, like Mormonism and Buddhism. And there is good reason for this: The doctrines were written down by people who didn’t know how the world worked. Except for Mormonism, which is recent, they were written down when we didn’t know that the Earth orbited the Sun! — Krauss, Lawrence. A Universe from Nothing: Why There Is Something Rather than Nothing (p. 192). Atria Books. Kindle Edition.

Secondly, there was even no real consensus on the existence of black holes. Witness the famous bet between Kip Thorne and Stephen Hawking:

Wiki: In 1975, cosmologist Stephen Hawking bet fellow cosmologist Kip Thorne … that Cygnus X-1 would turn out to not be a black hole. In 1990, Hawking acknowledged that he had lost the bet. Hawking’s explanation for his position was that if black holes didn’t actually exist much of his research would be incorrect, but at least he’d have the consolation of winning the bet.

Decades ago I heard terms like quasars, which were sources of mysterious intense cosmic radiation. We now know these sources contain black holes. And we realize that likely every one of the billions of galaxies contains near its core one or more black holes. Even our Milky Way. And all black holes are not created equal. And there’s even debate about the role of black holes in galactic evolution — which came first — black hole as galactic seed or evolved core.

So, that Space.com article is a useful summary of the state of things, not just our view of black holes themselves but of the cosmic landscape1 and theories in physics.2 How the scale of things works, at 10^n and 10^-n. Mind-boggling stuff indeed.

 

[1] Science has discovered new “dots” to connect for our world view. Does a philosophy based on the notion that the Earth is the center of the universe (or is only a few thousand years old) retain any credibility? Or a perspective based on the universe being less than billions of years old?

[2] “That word — infinite — is a hard pill to swallow. When infinites appear in the mathematics, it’s a signpost that we’re doing something wrong, that our machinery isn’t quite up to the task. We’re missing something. … we know our theoretical models (i.e., general relativity) are incomplete. There isn’t really a singularity at the center of a black hole. But we simply don’t understand strong gravity at small scales. That’s the domain of a full-on quantum theory of gravity, which we haven’t cracked despite decades of trying. Hard.” — Paul Sutter, On the Existence of Black Holes, September 11, 2017.

6 thoughts on “Beyond the infinity of black holes

  1. Space.com posted an article today about research on the center of the Milky Way galaxy: “Wild 360-Degree Video Lets You See the Milky Way As a Giant Black Hole Would.”

    Ever wish you could see the galaxy from the perspective of a black hole? A new 360-degree simulation that uses data from NASA’s Chandra X-Ray Observatory is helping astronomers better understand more than 22 stellar giants found at the center of the Milky Way galaxy.

    The simulation, unveiled here Wednesday (Jan. 10) at the 231st meeting of the American Astronomical Society (AAS), allows you to view over 20 Wolf-Rayet stars, which are massive stars orbiting the center of the Milky Way from a distance of about 1.5 light-years.

    There’s a YouTube video.

  2. Space.com February 12, 2018: “Behold the Mighty Quasar: The Science Behind These Galactic Lighthouses.”

    Quasars turned out to be black holes even bigger than Sagittarius A*, reaching into the billions and even tens of billions of solar masses.

    It’s not the black holes themselves emitting all the radiation — they are “black,” after all. Instead, as countless tons of material fall into the black hole, it compresses as it all tries to squeeze through the relatively narrow door of the event horizon together. That compression, plus friction, plus the release of all the gravitational potential energy, brings the temperature of the gas up to incredible highs. And it’s that hot, compressed gas that emits the copious amounts of radiation.

    A single supernova outshines an entire galaxy for a few weeks. A single quasar can outshine 10,000 galaxies for millions of years. Take that, supernovas, you chumps.

  3. Speaking of monster black holes, this Space.com article (May 15, 2018) “Scientists Just Found the Fastest-Growing Black Hole. Here’s How Fast It ‘Eats’” discusses “the fastest-growing black hole ever found.”

    Researchers used newly released data from the European Space Agency‘s Gaia satellite to confirm that the brightly shining object is a black hole, which appears to have been the mass of about 20 billion suns when the light was released and was growing by 1 percent every million years, researchers said in a statement released today (May 15).

    “This black hole is growing so rapidly that it’s shining thousands of times more brightly than an entire galaxy, due to all the gases it sucks in daily that cause lots of friction and heat,” Christian Wolf, an astronomer at the Australian National University and first author on the new research, said in the statement.

  4. And this Space.com article talks about quasar colors: “One Quasar, Two Quasar, Red Quasar, Blue Quasar: A Seuss-Like Space Color Mystery Explained” by Elizabeth Howell (Sept 6, 2019).

    A team at Durham University in the UK say they have discovered a phase in the evolution of quasars — galaxies with a very active black hole in the center — that could provide more insight into the curious life of these objects.

    Most quasars have a blue-ish tinge, …

    Specifically, Durham says that red quasars “are likely to be the result of a brief, but violent, phase in the evolution of galaxies when their black holes are ejecting large amounts of energy into the surrounding dust and gas.” This energy emission carries away any gas and dust in the vicinity, leaving a blue quasar behind.

  5. Bald and hairy black holes?

    Space.com > Stephen Hawking Was Wrong. Black Holes Are Bald by Rafi Letzter (September 17, 2019) – “according to the no-hair model, black holes are all uniform singularities.

    That 2017 [gravitational] wave was a big deal: For the first time, astronomers had a tool that could detect and record it as it passed, known as the Laser Interferometer Gravitational-Wave Observatory (LIGO). That first wave was the result, they found, of two black holes crashing together far away in space. And now, a team of astrophysicists has taken another look at the recording [and the overtones of that gravitational wave] and found something others thought would take decades to uncover: precise confirmation of the “no-hair theorem.” This essential aspect of black hole theory dates back at least to the 1970s — a theorem that Stephen Hawking famously doubted.

    When physicists say black holes don’t have “hair,” said Maximiliano Isi, a physicist at MIT and lead author of the paper, they mean that astrophysical objects are very simple. Black holes only differ from each other in three ways: rate of spin, mass and electric charge. And in the real world, black holes probably don’t differ much in electrical charge, so they really only differ in terms of mass and spin. Physicists call these bald objects “Kerr black holes.”

    It’s even possible that the signal from the overtone isn’t real, but occurred by mere chance due to random fluctuations of the data. They reported a “3.6σ confidence” in the overtone’s existence. That means there’s about a 1-in-6,300 chance that the overtone isn’t a true signal from the black hole.

    As instruments improve and more gravitational waves are detected all of these numbers should become more confident and precise … it’s always possible that black holes aren’t completely bald — they may have some quantum peach fuzz that’s simple too soft and short for our instruments to pick up.

  6. Phys.org > “Nearly extreme black holes which attempt to regrow hair become bald again” by Theiss Research (November 15, 2019)

    Burko and his colleagues Gaurav Khanna of the University of Massachusetts Dartmouth and his former student Subir Sabharwal, currently with the Eastamore Group, showed in a paper just published in Physical Review Research that …

    In addition to a maximal value of charge, there is also a limit for how fast a black hole can spin. Black holes that spin at the maximal allowed rate are therefore also called extreme black holes. We describe both maximally charged and maximally spinning black holes by the name extreme black holes, as there are many similarities between the two. The new hair was originally found for a very useful toy model for black holes, specifically black holes that are spherically symmetric and electrically charged. But black holes in reality are neither. Instead, we wanted to find out if this hair can be found also for spinning black holes,” said Burko.

    The team showed that for the nearly extreme spinning black holes the hair [a massless scalar field] is a transient behavior. At intermediate times nearly extreme black holes behave like extreme black holes would, but at late times they behave like regular, non-extreme black holes. “Nearly extreme black holes can pretend that they are extreme for only so long. But eventually their non-extremality becomes manifest,” Burko summarized. “Nearly extreme black holes that attempt to regrow hair will lose it and become bald again.”

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