Seth Fletcher

I wanted to like this, but it just never really grabbed me. The coverage of the physics seems too surface level, the overarching narrative was basically “this guy thought imaging a black hole would be good but it costs money and he thought he was more important than anyone else”, and it really didn’t even explain the questions they thought the images would answer particularly well.

It’s not terrible. Most of the science is accurate enough and it does show some of the technical difficulties of capturing distant space objects. But I can’t recommend it unless you’re really interested in black holes, and if you are I’d look at Hawking’s Black Hole book (which I haven’t read yet) or the Black Hole War by Leonard Susskind (which I have and enjoyed) first.… (mehr)

“The so-called hair-theorem maintains that they can be entirely described by three parameters: mass, angular momentum, and electric charge. They have no bumps of defects, no idiosyncrasies or imperfections – no ‘hair’.”

In “Einstein's Shadow: A Black-Hole, a Band of Astronomers, and the Quest to See the Unseeable” by Seth Fletcher

“There are actually three principles that come into conflict at a black-hole horizon: Einstein’s equivalence principle, which is the basis of general relativity; unitarity, which requires that the equations of quantum mechanics work equally well in both directions; and locality. Locality is the most commonsense notion imaginable; everything exists in some place. Yet it’s surprisingly hard to define locality with scientific rigour. A widely accepted definition is tied to the speed of light. If locality is a general condition of our universe, then the world is a bunch of particles bumping into one another, exchanging forces. Particles carry forces among particles – and nothing can travel faster than the speed of light, including force carrying-particles. But we know that locality sometimes breaks down. Entangled quantum particles, for example, would influence one another instantaneously even if they were in different galaxies. […] And after all, the whole reason black holes hide and destroy information is because of the principle of locality – nothing can travel faster than the speed of light, and therefore nothing can escape a black hole. If some sort of non-local effect could relay information from inside a black hole to the outside universe, all was well with the world.”

In “Einstein's Shadow: A Black-Hole, a Band of Astronomers, and the Quest to See the Unseeable” by Seth Fletcher

“The 20th century produced two spectacularly successfully theories of nature: general theory of relativity, and quantum theory. General relativity says the world is continuous, smoothly evolving, and fundamentally local: influences such as gravity can’t travel instantaneously. Quantum theory says the world is twitchy, probabilistic, and non-local – particles pop in and out of existence randomly and see to subtly influence one another instantly across great distances. If you’re a scientist who wants to dig down tot eh deepest level of reality, the obvious question is: which is it?”

In “Einstein's Shadow: A Black-Hole, a Band of Astronomers, and the Quest to See the Unseeable” by Seth Fletcher

Fascinating stuff but once again inspires some readers with more questions:

1. The silly one. Is it possible that Black-Holes are actually a life-form simply moving through space?
They have found a way to attract, trap and ultimately consume what they need to grow.

2. What is the nature of the material ejected (by M87) as opposed to the material ingested?

3. If different, what material, if any, has been left behind inside the Black-Hole, M87?

4. Probably also silly. If the jet of material is shooting out from the Black-Hole (M87), does this mean that this material is traveling faster than the speed of light? We have been told that even light cannot escape from a Black-Hole;

5. What about the sexual connection? (This question always pops up when talking about Black-Holes. Why?).

My answers:

1. Yes very silly. Complete nonsense;

2. Ionised matter accelerated to relativistic speeds. It's not stuff being ejected from inside the black hole itself it's matter and energy ejected from the excretion disc. Black-holes theoretically can evaporate over time via hawking radiation in the form of thermal energy;

3. Not really understood however since no information about what has fallen into the black-hole is retained so in that sense it has to be different;

4. Nothing can travel through space-time faster than the speed of light. Actually light has nothing to do with it. It's the speed of causality;

5. Spout I must. Since I first learned about black-Holes many eons ago in my teens, they've seemed most compelling as emblems of obscenity (literally, off scene) and extremity, paralysis and paradox. There is some kind of human projection into understanding the universe (vide Willard Quine on under determination of scientific theory), and black holes seem like a high watermark of human interest sneaking into developing hypotheses using mathematical and objectively measuring tools. How can that happen, you ask? Somehow, the full proof wall develops a crack and human reality--you might liken it to Kierkegaard's infinite interest, without his theological bent--rushes in. (Another powerful example from classic lit is the door opening at Garcin's demand in “No Exit” by Sartre) Black-Holes are teasingly and luridly sexual, gapingly and irresistibly dangerous, appallingly and exquisitely frightening, puzzlingly and perturbingly unfathomable. The bizarre end of the empirical quest through modern history is something you "a priori" can't directly see. Our math either has to make uncomfortable moves to accommodate them while retaining some sense of a "finite" universe, or give up the ghost of such a universe and joyride the slippery slope into metaphysics. They have a human face--I'm wagering more than they do not. As so many on the social sciences side of the fence see it, reality is social reality, and that seems truer as I age. There!

With my reviews of physics’ books, I get all sorts of questions regarding Black-Holes. Because I can’t be bothered to answer them as they trickle in, here’s a summation of some of them (with my answers to the best of my knowledge):

1. Do we have any evidence regarding the interactions of black-Holes?
Answer: There is speculation that at least some forms of 'gamma ray bursts' (intense but short term bursts of radiation high energy radiation detected by satellites) may be due to colliding black holes formerly in binary systems. Some bursts are probably due to binary pulsars so it is possible some arise from colliding black holes. Surprisingly nothing more dramatic than an even larger black hole is theorised to develop after the collision;

2. How does space-time behave when two black-Holes interact at a distance? Can this interaction provide interesting ways to move through space-time: without getting trapped or ripped apart?
Answer: The options for using variations on black holes as gates for space travel don't look hopeful but are under theoretical investigation;

3. How do black holes influence matter-energy in our solar system, beyond maintaining our orbit around Sag A? Can we exploit this interaction in any way?
Answer: The black-Hole at the centre of our galaxy isn't that influential. It is rather lightweight compared to the total mass of our galaxy. If it disappeared today we would still travel around the galaxy's centre. Whether the black hole there formed there and drew mass progressively around it to form the galaxy, or whether it formed elsewhere and drifted into the centre isn't certain, though the former case is favoured. But its mass is relatively insignificant compared to the rest of the galaxy - it just happens, for whatever reason, to be at the centre;

4. Is it possible that what we see as the death of many solar systems results in the birth of a universe?
Answer: Vide point above;

5. Can the preponderance of black-Holes account for some of the missing mass of the universe?
Answer: Black-Holes, of a smaller size than those in the centre of galaxies, have been postulated as the 'missing mass' but the required number hasn't been found using a number of strategies. It is more likely the missing mass is due to currently undetected new fundamental particles. But you never know....

Bottom-line: As a side note, until all of the information is properly correlated, and all error sources identified, namely with the data coming from the South Pole Telescope, we won’t get any direct confirmation of the existence of Sagittarius A* or M87 black-Holes via radiation imaging. So, hold your horses.… (mehr)