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Kosmologisk hammock

Fastnar för ett par svar från kosmologen/fysikern Claudia de Rham i en intervju med henne med anledning av hennes bok The Beauty Of Falling: A Life In Pursuit Of Gravity

… Every day, I try out an idea and it fails. And there’s something beautiful in failing, and falling. The book is about gravity, but it is also about embracing this falling, because it’s how we get better — it’s how we understand the world. With gravity, failing has an even deeper meaning. The way that we describe gravity at the moment is with Einstein’s general theory of relativity, which predicts its own downfall.

How so?

If you have a gravitational collapse of matter, the endpoint will be in a black hole, with a singularity at its centre. The singularity means that, if you agree with Einstein’s theory, some quantities you can measure would be infinite. What that really means is that the theory has stopped working there, and it gives a prediction that doesn’t make any sense. So the theory itself is telling you that you shouldn’t trust it any more. And that is not something to be ashamed of. It is an opportunity to learn something more.

Davide Castelvecchi, “Cosmologist Claudia de Rham on falling for gravity“, Nature, 2 april 2024

Det där senare svaret är säkert skåpmat för någon som är bekant med relativitetsteorin, svarta hål och kosmologi, men jag gillar alltid en märgfull förklaring.

Nature har för övrigt en recension av Jonathan Haidts The Anxious Generation, som inleder starkt:

Two things need to be said after reading The Anxious Generation. First, this book is going to sell a lot of copies, because Jonathan Haidt is telling a scary story about children’s development that many parents are primed to believe. Second, the book’s repeated suggestion that digital technologies are rewiring our children’s brains and causing an epidemic of mental illness is not supported by science. Worse, the bold proposal that social media is to blame might distract us from effectively responding to the real causes of the current mental-health crisis in young people.

Candice L. Odgers, “The great rewiring: is social media really behind an epidemic of teenage mental illness?“, Nature, 29 mars 2024