L'irresistibile attrazione della gravità: Viaggio alla scoperta dei buchi neri

by Luciano Rezzolla

Perché una mela cade dall'albero anziché galleggiare nello spazio? Be', è merito - o colpa - della gravità, lo sappiamo tutti. A scuola ci hanno insegnato che è questa forza a tenerci agganciati alla superficie del nostro pianeta, mentre lui ruota su se stesso e intorno al Sole. Ma il nostro corpo la conosceva ben prima che la incontrassimo sui libri di testo: appena venuti al mondo sapevamo già reagire ai suoi stimoli, e di lì a qualche anno abbiamo imparato a gestirla senza nemmeno pensare, magari mentre... corriamo giù per le scale. A noi sembra un traguardo da nulla, ma per i robot è ancora un problema quasi insormontabile. Insomma, il nostro rapporto con la gravità dura letteralmente da una vita, ed è anche l'unica interazione fondamentale della fisica di cui siamo coscienti. Tanto da sognare di liberarcene. Eppure, quanto la conosciamo davvero? Sappiamo cosa sia lo spazio-tempo, in cosa consista la sua curvatura e come si produca? Siamo pronti ad accettare che il tempo possa accelerare o rallentare a seconda del posto in cui ci troviamo? Sappiamo cosa sono le onde gravitazionali, o come funziona un buco nero? L'astrofisico italiano che ha realizzato per primo, assieme ai colleghi del progetto Event Horizon Telescope, delle immagini fotografiche di un buco nero supermassiccio ci invita a un viaggio per trovare risposta a tutte queste domande, e a molte altre. Ad esempio: com'è possibile fotografare un buco nero se per definizione cattura tutta la luce che lo colpisce? Con piglio divertito ed enorme passione, Luciano Rezzolla è pronto a guidarci alla scoperta dei più profondi misteri del cosmo. Senza mai banalizzare le complessità dell'astrofisica, ma pronto a illuminarle per noi attraverso analogie immediate e fulminanti, ci condurrà passo dopo passo a scoprire la verità su un fenomeno che, prima ancora di attrarre i nostri corpi, attira da sempre la nostra curiosità.

Genres: Science, Nonfiction, Space

333 pages, Kindle Edition

First published December 6, 2023

Reviews

[Douglas · Rating 3 out of 5]

This is probably a very good book. But I am just not smart enough to follow it. But it is fun to try and figure out what gravity is. It is much more than an apple falling on your head. It's some sort of energy or wave that holds our Universe together.

[Dana Nourie · Rating 5 out of 5]

I really enjoyed this book. The writing style is smooth and easy to follow, and way Luciano builds on concepts is helpful for understanding the crazy way gravity works.

I have found finding good books on gravity challenging. Good as in meeting my leveling of understanding but not throwing me to the wolves of the mathematics of Einstein’s equations. Books about gravity either go from too simplistic to wtf? This book is just right.

The the author takes us on a walk through Newton’s laws and classical mechanics and why those continue to be a mainstay, then venturing into bent spacetime and Einstein’s theories.

The book then goes into neutron stars, graveyard, and black holes crazy gravity and how they were recently photographed and how we are now detecting the collision of black holes and neutron stars via gravitational waves.

This book for me was very enjoyable and helped my understanding of gravity and these bizarre objects such as neutron stars and black holes.

[Dul Bat · Rating 5 out of 5]

“Gravity is the manifestation of spacetime curvature.”
After reading this I think I have some idea about spacetime, Einstein’s relativity, neutron stars, black hole and what actually is this mysterious interaction called gravity. The author is a team member of the Event Horizon Telescope Collaboration, team who took the first ever picture of a black hole. I love how he simplified complex equations into word form so that any general audience can grasp the concept behind them.

[Brenda Greene · Rating 3 out of 5]

Translated from German, in a quaint, old fashioned, semi chatty, semi lecture type tone, Luciano starts with sources of knowledge, requiring that the reader be prepared to use their imagination.

He is very encouraging, explaining things like compactness vs density. The vectors on a flat plane may have got lost in translation, or at least I got lost or couldn't see the point. He explains gravity is not a force but an outcome (I think) of mass bending spacetime. How or why gravity is described as an accelerating force on earth when he points out it is not is unknown.

Luciano explains why Einsteins equations haven't really generated a lot of research - just wild speculation - because Newton's laws work well enough and more simply on earth. It's an inciteful comment about the nature of theoretical physics.

He points out that thousands of theoretical mathematical models are generated and even if one matches observations, it could be wrong. We have no way of knowing.

Luciano is quite up front about the lots of unknowns, then almost casually says dark energy and dark matter exist, without any careful comment at all. Maybe these things have nothing to do with gravity?

It is good to know that our galaxy is largely flat spacetime, and that gravity is fairly constant throughout. Except for a massive black hole. Oh, and quasars. And neutron stars. And other celestial objects that may or may not be in our galaxy. He is, however, enthralled by them, which is fair enough.

The neutron stars are obviously his love as there is quite a detailed diversion with an after thought about gravity. The thread of the book gets lost here, as Luciano strays away from simple explanations, useful comparisons and analogies into imagined and complex structure based on, well, nothing.

There are many logic leaps. For example, because a neutron star has been found to be more than 2 solar masses, there must be more massive ones, however there will not be many more massive ones because one more neutron can make the 2 solar mass star collapse but one tap with a hammer can not. Really? His graph shows large errors of uncertainty. For those as confused as me, Luciano refers to a paper he wrote.

His expertise shines as he introduces a number of scientific terms (e.g. tidal flows) with no explanation and describes links between various equations (these he has simplified because some terms are not real). The logic leaps and their implications are impressive. Luciano says don't worry, I will explain.

At this point I wondered if I had picked up a supporting text book for his post grad students, but no, Luciano is clear this is a popular science book. He makes a few playful jokes however this is German humour, and he helpfully explains the literal word play.

This book is about what gravity does when subject to specific compactness of masses (which spin and have charge) which produce massive bends in spacetime. These bends evolve as stars evolve and implode. And other things may also happen. I think.

Luciano gives a helpful story about a couple of adventurous astronauts who picnic near an event horizon. I love that they take pastries and tea. Unfortunately the point he is making about the relativeness of time is inferred and not well demonstrated.

There is just too much in Luciano's fine mind for a clear, popular science book. Some bits are great. Other bits diverge into complex mathematical concepts then take tangential journeys into the wondrous parallel beauty of maths and the universe.

I almost gave up, however because some concepts may have literally got lost in translation, I ploughed on. It was worth it. Luciano gave a succint, beautifully conveyed summary of the event horizon telescope. Then the real pleasure of the book began.

There is a helpful table about the differences between electromagnetic light energy (photons) and gravity. A description of LIGO. The big preamble to get to this point starts to make sense. A mention of LISA and a graph of what is possibly able to be detected.

What was really good was how complicated it is to even get observations from telescopes. Even if earth sized. Luciano explains this clearly and brilliantly.

Then we are back into his passion. The maths around event horizons, paired stars, specific celestial objects he has studied. Inference to star evolution which has no structure and assumes you already know how stars evolve. At this point, so close to the end of the last chapter, I gave up.

Luciano poses questions he is sure his readers will ask, which is sweet, however none were questions that ever crossed my mind. I am just not sure that he knows who an audience reading a popular science book on gravity is. It really needs a different structure.

The book would benefit by being cut down by a third. A chapter on each stage of the evolution of a black hole (star, neutron star, supernova), then a chapter each on the properties of black holes (mass, spin, charge), then a chapter each on detectors (event horizon, Lidar), then a chapter each on objects (super big, medium, small). A chapter on scale and distance. One on spacetime distortion.

There are black and white images in the text and some coincide with coloured plates in the centre.

[Marco Dp · Rating 4 out of 5]

Molto ben scritto ed interessante, chiaro nelle spiegazioni ed accompagnato da immagini esaustive che ne arricchiscono il contenuto. Gli ultimi due capitoli, forse, sono i più duri da digerire in quanto l'autore affronta alcuni tecnicismi non proprio alla portata dei non addetti ai lavori, nonostante siano accompagnati da spiegazioni dettagliate che aiutano ad afferrare quantomeno il concetto generale espresso dalle equazioni trattate.
In ogni caso, non lo consiglio a chi non possiede già una base di conoscenze naturali, fisiche e matematiche per le quali ci sono sicuramente testi più accessibili di questo. Giustamente, aggiungerei, essendo una lettura che affronta un particolare argomento pressoché ostico della fisica quantistica.

Per il resto, il testo è contornato da considerazioni personali, esperienze, esempi che ne rendono la lettura coinvolgente e piacevole alle condizioni di cui sopra.

[Maria Beltrami · Rating 5 out of 5]

Rezzolla starts from history and myth, from what men, little by little, have understood about their standing firmly on the ground and from there turning their eyes to the sky, farther and farther, deeper and deeper, until they realise that space is also time, and that the farther you look the further back in time you go. A very fine book indeed, in the classic style of the best science divulgation, one that reads like a novel and for that very reason plants its seeds firmly in the mind: ""do non hesitate to use your curiosity and ask yourself questions, even questions that may seem bizarre. Let your intuition be your guide, but not your master".

[Rudi · Rating 4 out of 5]

Het boek is soms wat technisch droog , de schrijver zijn passie voor zijn werk is als leek niet altijd even gemakkelijk volgbaar toch heeft de schrijver zijn best gedaan om het uit te leggen,
Hoe kan men zwaartekrachtsgolven detecteren? De uitleg is een uitdaging voor een lezer die niet thuis is in de astronomie, de wiskunde, de technische apparatuur, ergens vind de schrijver wel begrijpbare vergelijkingen,
Het doet me wel wat nadenken over de waarnemingen , de waarnemers bewegen ook mee door de tijd al bewegend een bewegend doel observeren en terugkeren naar de observatie plek in de ruimte is ook niet mogelijk ,
Interessant boek ,

[Andrea Wenger · Rating 4 out of 5]

In a conversational, easy-to-read style, the author explains the latest understanding of gravity. The book is a deep dive into the subject of black holes for those who are interested in the topic.

Thanks, NetGalley, for the ARC I received. This is my honest and voluntary review.

[Art Meyer · Rating 5 out of 5]

If you want to know about black holes and neutron stars, this book is for you. Luciano Rezzolla shares his wonder of astrophysics. One of the curiosities that he shared is how the coalescence of two neutron stars could create heavy elements.

[Alvin Walter · Rating 4 out of 5]

Irresistible Read

It was loaded with many highly scholarly scientific facts that I enjoyed being exposed to even though many were far over my head.

[Frank Lang · Rating 4 out of 5]

Dieses Review bezieht sich auf die deutsche Übersetzung aus dem C.H.Beck Verlag.

Das erste Foto eines schwarzen Lochs wurde anno 2019 veröffentlicht und viele fragten sich, was an diesem unscharfen Knubbel so besonders sein soll, dass die Welt der Wissenschaft so in Aufruhr geriet. Wenn ich es richtig verstanden habe, so gehörte der Autor Luciano Rezzolla mit zu dem Team, das dieses Foto erstellt hat. Insgesamt 350 Forscher und Forscherinnen haben sich zu der Forschungsgemeinschaft »Event Horizon Telescope« zusammengeschlossen, wobei der Autor einer von dreizehn Mitgliedern des Exekutivkomitees war.

»Richtig verstehen« ist dann auch das passende Schlagwort, denn obwohl ich naturwissenschaftlich interessiert bin, sind mir astrophysikalische Zusammenhänge rund um schwarze Löcher ein Rätsel. Auch nach dieser Lektüre. Das liegt vor allem daran, dass sich dieses Gebiet mit Themen befasst, die außerhalb der Vorstellungskraft des Menschen liegen. Der Autor versucht, in diesem Buch die Zusammenhänge rund um die Schwerkraft dem Laien näherzubringen, der eine gehörige Portion naturwissenschaftliches Interesse mitbringen muss, die mit anspruchsvollen populärwissenschaftlichen Veröffentlichungen standhalten muss.

Luciano Rezzolla tastet sich in seinem Buch nach und nach dem Thema Schwerkraft an. Dabei beschreitet er den Weg von einfachen Zusammenhängen hinsichtlich der Schwerkraft über die Raumzeit und Neutronensternen hin zu schwarzen Löchern. Natürlich beschreibt es auch in aller Ausführlichkeit, wie dieses Foto entstand und was das Besondere an dessen Aufnahme war.

Fazit
Der Leser muss zwingend eine gehörige Portion naturwissenschaftliches Interesse mitbringen. Viele Erklärungen in diesem Buch dürften für den interessierten Leser verständlich sein, ich bin bei einigen Passagen allerdings ins Trudeln geraten und könnte nicht alles nachvollziehen, was dort geschrieben stand. Dennoch ein sehr interessantes Buch für entsprechend interessierte Leser.

[CeebeeS · Rating 5 out of 5]

Ein wirklich lesenswertes Buch. Ich lese normalerweise keine Bücher dieser Art, Physik ist so gar nicht mein Ding. Aber dieses Buch hat mich begeistert, ich hatte das Gefühl endlich was verstanden zu haben. Wenn Physik so in der Schule erklärt worden wäre, hätte es mir wohl möglich Spaß gemacht! Mir hat das Buch aus mehreren Gründen sehr gut gefallen, unter anderem habe ich etwas so komplexes wie Raumzeit, schwarze Löcher und Neutronensterne mit Leichtigkeit gelernt ohne es zu merken.

[Ulrike Bungert · Rating 3 out of 5]

Ich kann mich einfach nicht erwärmen für die schwarzen Löcher....