The size of the photographed black hole event horizon

Obtaining the first-ever photograph of a black hole was an impressive feat. We tend to think of black holes as being tiny and they are. A black hole represents a singularity in space-time where gravitational field becomes so large that there is extreme curvature of space. But the ‘event horizon’ of a black hole, the region inside from which no light can escape, need not be tiny. It is the event horizon that gives rise to the dark region seen in the photograph and the size of the event horizon for any mass M is given by the Schwarzschild radius that is equal to 2GM/c2, where G is the gravitational constant and c is the speed of light.

The black hole at the center of the galaxy M87 that was photographed has a mass 6.5 billion times the mass of the Sun and thus its Schwarzschild radius is about 1.9×1010 km. This is quite large, about three times the distance of the planet Pluto from the Sun, which is 5.9×109 km.

The Julian Assange case and freedom of the press

The removal of Julian Assange from the London embassy of Ecuador following the revoking of his asylum has raised concerns about the implications for press freedom. The US immediately unsealed a secret grand jury indictment that it had obtained earlier and used it to demand his extradition to the US. The main charge against him is that of a conspiracy to hack into government computers to obtain secret documents.
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Netherlands backtracking on sex workers?

Sex work has long been legal in countries like the Netherlands. But now a petition has been launched to change the law and adopt the so-called ‘Nordic model’ of Sweden, Norway, Iceland, Northern Ireland and France that makes it an offense for people to buy the services of sex workers. The petitioners claim that legal sex work leads to exploitation and human trafficking. What is surprising is that the 42,000 young people have signed the petition. What is not surprising is that many of these young people are religious.
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A final Brexit deadline – until the next one?

The 27 other leaders of the EU offered the UK’s prime minister Theresa May, and she accepted, a new deadline of October 31, 2019 to pass a Brexit plan. She has told parliament that if they pass a plan earlier, they can withdraw earlier. She also had to face the humiliation of promising “sincere cooperation” while still in the EU and imploring the EU to ignore the threats from some of her backbenchers that while in the EU, they would disrupt its workings, threats that resulted in France urging language that would summarily expel Britain if they misbehaved. The French proposal was deemed to be illegal but that it was raised showed how fed up some countries are with the UK.
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The case against metrics

Anyone who has worked in any fairly large organization will sooner or later be confronted with metrics to measure performance. The idea of metrics, setting out measures to see if one is meeting one’s goals, is not in itself bad. What is problematic is when metrics are created whose purpose is not to provide valuable feedback but are used almost exclusively to determine rewards and punishments. Then one frequently finds that metrics distort performance as people game the system to meet the requirements of the metrics even if the actual results of doing so are deleterious. Badly designed metrics also focus on the things that can be measured easily rather than on the things worth measuring.
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Minimalism

In this video Sasaki Fumio, who has been described as Japan’s most famous minimalist, describes why he reduced the number of things he has to just 150 and what made him change to a life of minimalism. Although we may think that minimalists have to be highly organized to live as they do, paradoxically he thinks that most people who are minimalists are like him, people who are unorganized and untidy and if they have a lot of things, they are just surrounded by mess. Minimalism is their way of getting control over their immediate environment by not having a lot of stuff to deal with.

I am a pretty organized person who puts things away and keeps track of things and that is maybe why I have not felt the urge to adopt minimalism in this extreme form, though I do try to minimize the number of things that I buy and own. I do share with Fumio being quite content to eat the same or almost the same food day after day. The same with clothes. That simplifies life considerably.

The problem of Trump’s mental state

I suspect that many readers of this blog also read Marcus Ranum over at stderr but just in case you don’t, I want to refer you to a post he made today that deals with something I too have been mulling over, and that is whether we are dealing with a president who is slowly, before our very eyes, showing signs of a cognitive degeneration and if so how best we should respond to it.

It is not recommended even for professionals in the field of mental health to make remote diagnoses of the cognitive state of people. It is hard to say when a person’s brain is malfunctioning because that would imply that we know what ‘normal’ brain functioning looks like. How do we distinguish between words and actions that are deliberately malevolent and those that are inadvertent, since all actions are the result of brain functions? This is the problem that confronts judges and juries when a defendant raises the insanity defense.

And of course, even if Trump has degenerative brain problem, it should not prevent us from harshly criticizing and mocking the actual policies he is setting in motion. But as Marcus says, it perhaps should make us more cautious about mocking his verbal misstatements. This is not easy to do since his actions are so hateful that one wants to throw the kitchen sink at him.

I do not listen to Donald Trump’s speeches or even his press conferences. The only glimpses I have of his speech are when short clips of them appear on the news or the comedy shows so the disturbing patterns that Marcus describes were not noticed by me.

The EU seems to view the UK as a pest

Today is the day that British prime minister Theresa May is to go to Brussels to present the UK’s plan for withdrawing from the EU. But of course she has no plan. The EU is rejecting her appeal for a short extension until June 30 to arrive at a plan, rightly concluding that she will not be able to do so within that time frame. The EU has the option of rejecting any extension, causing the UK to crash out with no deal on Friday. But they are not likely to be that hard-nosed and are insisting on a longer deadline, until the end of this year or until the end of March 2020. That seems reasonable, except of course that it will make the hard-core Brexiters apoplectic since it will involve the UK staying in the EU longer and also taking part in the EU elections for the European parliament. If the UK does not hold EU elections between May 23-26, they will be automatically ejected from the EU on June 1.
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