This book is a lot. It starts with cosmology and the Big Bang, goes into particle physics to explain what dark matter is, touches on theories of the origin of life, finally gets to the fossil record and what that tells us about mass extinction events, goes into some concepts of probability theory and statistical significance, then describes large scale features of the Milky Way and our solar system’s traversal through it.

All of this is used to illustrate her idea (which she is very careful to describe as speculative and a “thought experiment”) that there is a disc of dark matter, much thinner than the distribution of normal matter, through the central plane of the galaxy, and that the spike in gravity caused by this disc is responsible for knocking objects out of the orbit of the Oort cloud at the edge of the solar system every 30-35 million years and sending big spikes in the number colliding with Earth, causing mass extinction events including the death of the dinosaurs.


Randall is very clear, though out the work, that some ideas are not established yet and should not be taken as factual, but she does heavily reference other academic work on the variety of fields involved. As a nonexpert I am unable to verify all of the background material, but provided there are no glaring omissions or misrepresentations I believe she makes a compelling case for her theory.

Overall this book is densely packed with a lot of science and will take some thought to follow, but the frame of her “dark matter killed the dinosaurs” hypothesis allows the book to flow reasonably well. ( )

I put this book on the bedtime story shelf and my fourteen-year-old picked it up, which means that I read this whole thing out loud to my family. There were times when I thought that this book's structure wasn't very friendly to a read aloud format, as there was a LOT of repetition and circling back on theories which sometimes made me impatient to read so slowly. But really, it probably helped the kids, especially as we read it one chapter at a time, so it helped with the "where we left off..." reminders.

Okay, so there is a really interesting premise at the heart of this book, and that is: is there a cyclical nature to mass extinctions in the fossil record supporting evidence for cyclical catastrophic meteor strikes? And if so, could that cycle be linked to a structural issue in our solar system — and if so, could that structural issue be related to dark matter? Clearly, there are a LOT of interconnected features to unpack here, which means that even if at the end, you are unpersuaded by the thesis that dark matter killed the dinosaurs (which is not actually a foregone conclusion of this book), you still have learned about the fossil record, mass extinctions, meteor strikes, the structure of the solar system, dark matter, and predictive modeling. In a way, that is more FUN — a depiction of the way that science searches for connections and patterns, and that you don't have to prove your hypothesis correct in order to learn an impressive amount about the universe.

A very worthwhile adventure. ( )

Donkere materie is onzichtbaar. Ze interageert alleen door middel van de zwaartekracht met gewone materie. Ze is nodig om te kunnen verklaren waarom het universum de vorm heeft die we nu waarnemen. Donkere materie is het onderzoeksdomein van Randall en van daaruit beschrijft ze de ontwikkeling van het universum en van het zonnestelsel. Wie het verschil wilt weten tussen meteoroïden, meteorieten, meteoren, meteorologie en meteoritica is hier aan het juiste adres.

Ons zonnestelsel beweegt door de Melkweg. Het is een dynamische omgeving. Soms loopt het mis, getuige daarvan de inslagkraters op aarde. De meest bekende inslag is verantwoordelijk voor het verdwijnen van de dino's, maar blijkbaar wordt de aarde met regelmaat getroffen door meteoroïden. In een poging om, onder meer, die regelmaat te verklaren, ontwikkelde Randall met haar medewerkers een nieuwe theorie over donkere materie. Ze gaat ervan uit dat op zijn minst een gedeelte van die donkere materie met zichzelf kan interageren op andere manieren dan via de zwaartekracht, net zoals dat bij gewone materie het geval is.

Het is een speculatief model. Gedetailleerde metingen van de Melkweg zouden moeten uitmaken of het plausibel is. Donkere materie zelf kunnen we in elk geval niet rechtstreeks waarnemen. Het ziet er niet naar uit dat we de aard ervan zullen kunnen bepalen, laat staan die van de krachten die haar beheersen. Randall droomt ook even van 'donker leven', opgebouwd uit donkere materie, en daardoor immer voor ons ontoegankelijk.

Daarmee zijn we aanbeland bij de filosofische consequenties. Met donkere materie zitten we duidelijk op de limiet van het kenbare; de meest tastbare (als die term hier op zijn plaats is) vorm van Kants Ding an sich, een object dat ontsnapt aan elke vorm van waarneming en waarvan we het bestaan alleen indirect kunnen vaststellen. Al rekken we met deze beschrijving Kants begrip wat op. Je zou je ook de vraag kunnen stellen of we die donkere materie echt wel nodig hebben. Randall zelf verwijst even naar het scheermes van Ockham: de meest eenvoudige verklaring is de beste. Misschien is het gewoon wachten op iemand die met de juiste blik naar alle gegevens kijkt, een nieuwe Copernicus.

Wat in elk geval blijft hangen, is de periodiciteit van meteoroïde-inslagen. Randall blijft er wat vaag over: ergens tussen de 32 en de 35 miljoen jaar. De inslag die de dino's uitroeide, vond 66 miljoen jaar geleden plaats. Reken zelf even uit. Randall zelf hoopt dat we de gevarenzone net verlaten hebben. Waarschijnlijk maakt het niet veel uit: we hebben inmiddels geen meteoroïden meer nodig om een massa-extinctie op poten te zetten.

Het boek had overigens een betere eindredacteur verdiend. ( )

Sixty-six million years ago another day dawned over a Cretaceous earth. Life was carrying on as normal, but everything was about to change because heading towards the planet at an astounding speed was a ten-mile wide object. The impact of this object left a crater, traces of which can still be detected and managed to obliterate the dinosaurs and 75% of all the other species on the planet. The few that survived evolved into the huge variety that we have today and provided an opportunity for the mammal to thrive. It is now thought that this was not one of those, one in several million chance events, rather an effect of our solar system interacting with the wider universe and the gravitational influence of dark matter.

Randell has some interesting theories about dark matter, the pervasiveness of it in the universe and how the gravitational influence of dark matter causes disturbances in our galaxy and solar system. It is a substance that we know is there, but at present, we have no idea where it is, what it is or how to detect it. Quite elusive stuff, especially given how much of it there is out there. Randell writes with clarity on a difficult subject, although it is occasionally incomprehensible; but that is as much because I am fairly rusty at physics, rather than her explanations. She is well qualified to talk about this being Professor of theoretical particle physics and cosmology at Harvard, but this is one book that might be beyond the general science reader, even though they should probably give it a go. ( )

Fascinating. Informative. Just an astounding read(yes, pun intended). For someone who does not know the first thing about astronomy, this book is relatively easy to follow. The author draws out this wonderful story about comets, extinctions and dark matter. How does it connect? Why might the extinction of the Dinosaur be relevant to us today as the current dominating species(dominating for now)?

There are times when the science got a little "too much", but for the most part the author does good enough of a job in the writing that it feels as if she knows when to "stop". Still, the author does go as deep as is needed to explain the dark matter "stuff", the role of stars in the birth of the universe, asteroids/meteoroids and the Dinosaurs' Extinction(Kpg Extinction)'s role within this narrative. Personally, my fiction brain at the end of this book was, "there is so much sci-fi I can write based on this stuff! ". It was a very fun read. If you have the slightest interest in Dark Matter, why is it given the VERY inaccurate name of "Dark" Matter, the Dinosaurs' Extinction or just astronomy/particle physics in general, grab this book and I promise you won't regret it. Looking forward to read more stuff by the author. ( )