Einstein's Telescope: The Hunt for Dark Matter and Dark Energy in the Universe

by Evalyn Gates

Dark energy. Dark matter. These strange and invisible substances don't just sound mysterious: their unexpected appearance in the cosmic census is upending long-held notions about the nature of the Universe. Astronomers have long known that the Universe is expanding, but everything they could see indicated that gravity should be slowing this spread. Instead, it appears that the Universe is accelerating its expansion and that something stronger than gravity--dark energy--is at work. In Einstein's Telescope Evalyn Gates, a University of Chicago astrophysicist, transports us to the edge of contemporary science to explore the revolutionary tool that unlocks the secrets of these little-understood cosmic constituents. Based on Einstein's theory of general relativity, gravitational lensing, or "Einstein's Telescope," is enabling new discoveries that are taking us toward the next revolution in scientific thinking--one that may change forever our notions of where the Universe came from and where it is going.

Genres: Science, Physics, Astronomy, Nonfiction, Space, History, Nature

320 pages, Hardcover

First published January 1, 2009

Reviews

[Max · Rating 4 out of 5]

Gates explains the importance of gravitational lensing (Einstein’s telescope). She describes the technique’s use to get better images of distant galaxies and to locate concentrations of dark matter. Dark matter has mass and just like ordinary matter can be used to magnify distant objects. While dark matter is useful as a lens it can distort images and measurements if not accounted for. Thus we need to identify the distribution of dark matter in the universe. Significantly, this will allow us to get a clearer view of the cosmic microwave background. Knowing the distribution of dark matter is essential to understanding the evolution of galaxies, their clusters and their alignment throughout spacetime. In addition we will be better able to understand dark energy.

Gates begins with several chapters devoted to basic concepts. These provide a succinct review of the Standard Model and current theories about the Big Bang, the cosmic microwave background, dark matter, dark energy and the expansion of the universe. Her chapter on special and general relativity helps explains how gravitational lensing works. Massive objects and concentrations of mass warp spacetime bending light. The larger the mass the more it curves spacetime. Dark matter does not interact with light, but it does with gravity and thus while it can’t be seen, it can be identified by its gravitational influence on objects made of ordinary matter. Dark matter forms a spherical halo around galaxies and galaxy clusters. Dark matter was essential to the evolution of the galactic structures we see.

The universe contains about five times as much dark matter as regular matter, making dark matter an excellent resource for gravitational lensing. Most of a galaxy’s power as a lens comes from its dark matter component. A nearby galaxy or a galaxy cluster can act as a powerful lens to see a distant galaxy or cluster in more detail. The amount and distribution of mass is the critical factor. Knowing this allows efficient use of this mass as a lens. The lens created by a galaxy or cluster is not smooth but lumpy depending on which components lie between the viewer and object being viewed. Thus determining the distribution of dark matter is critical but problematic since we can’t see it.

The base case for the existence of dark matter is that without it there is not enough mass in galaxies to explain their rotation speeds, their stability and even their formation. A number of theories have been considered to explain this missing mass. Some theories look to undiscovered ordinary matter such as faint stars and planets that we haven’t detected. But by and large scientists do not believe it possible for undetected ordinary matter to account for the tremendous amount of missing mass. The leading theory is that the missing mass is accounted for by an undetected particle or particles that just barely interact with regular matter except through gravity. These theorized particles are called WIMPs (Weakly interacting Massive Particles). Other hypothetical particles such as axions are also theorized to make up dark matter. However attempts to find these particles in experiments including the Large Hadron Collider have been futile. A third avenue of thought is that something is wrong with our understanding of gravity and that general relativity needs some kind of an adjustment, obviating the need to find missing matter.

Gates discusses how gravitational lensing proves dark matter exists. By looking at distant stars and galaxies that lie behind nearer galaxies and galaxy clusters in a systematic way we can identify the amount of mass in the nearby galaxy or cluster based on its magnification effects on the distant object. After thousands, even millions of observations are produced, the distribution of mass is revealed in the nearby galaxy/cluster that is used as a lens. These studies document the spherical halo of dark matter that surrounds galaxies and clusters.

Particularly significant is a collision of two galaxy clusters that occurred one hundred million years ago. We see the stars of what is known as the Bullet cluster shoot through another cluster but its galactic gas is held back by the gas of the colliding cluster and separated from the stars, planets and other objects in the Bullet cluster. Gas comprises ninety per cent of the normal matter in a galaxy, yet gravitational lensing shows most of the Bullet cluster’s mass is where its objects are, not where the gas it left behind is. Dark matter does not interact with itself and thus it kept moving along with the galaxy’s objects. Dark matter uniquely explains this disparity of mass between the Bullet cluster’s objects and gas.

Perhaps more mysterious than dark matter is dark energy. Scientists believe that space itself is expanding overcoming gravity and separating galaxy clusters from each other at an ever increasing rate. The mass in galaxy clusters still have enough gravitational force to hold together, at least for now. Competing theories for what constitutes dark energy abound including: 1) The vacuum energy of space, a constant force referenced by Einstein’s cosmological constant, 2) Quintessence in which dark energy is variable over time, and 3) Modifications to general relativity that accommodate expansion with no extra source of energy required. Of course, the answer could be a bit of all three ideas. Nobody knows.

Understanding more about dark energy means we need a better picture of the amount and distribution of matter in the universe. This means identifying the cosmic structure of dark matter through time, creating a 3D image representing billions of light years. Gravitational lensing is an essential part of doing this. Depicting the web of dark matter pervading the universe would also identify the distortions it creates and enable us to get a clearer picture of the cosmic microwave background (CMB). That might enable us to identify ancient gravity waves in the CMB emanating from the Big Bang and help us validate the theory of inflation and its various models.

Gates’ presentation is straightforward and well structured. This brief review leaves out the many supporting details that give credence to her views. These details and the methodical way she builds her case make the book engaging. The text is enhanced by many helpful pictures and illustrations. Gates succeeds in showing that gravitational lensing is essential to map the distribution of dark matter in the universe. She provides an accessible explanation of why this knowledge is needed if we are to understand the evolution and future of the universe.

[Joe · Rating 4 out of 5]

As a doe-eyed graduate-level physics student, I have this terrible habit of reading books like Einstein's Telescope and falling completely in love with a very specific subfield of science. Then I'm all like, "Oh dip Evalyn Gates I could totally get into gravitational lensing to map dark matter halos around galaxies!" and then the next week I'm all like, "I love inflationary cosmology and am now a disciple of the anthropic principle see you soon Alex Vilenkin!"

I hope you weren't looking for a review here. I'll say only that it was terrific despite the fact that there are 10^36 acronyms in this book... really an astronomical number.

Booo.

[Emily · Rating 3 out of 5]

Whew! It took me six weeks to get through this astrophysics book. I haven't picked up a physics book since high school and was hesitant to start reading this. While this book was interesting, the subject matter was intense and I found myself re-reading sections two or three times to ensure I comprehended the concepts. Evalyn Gates does an excellent job of explaining Einstein's theories and how they are harnessing those theories to explore dark matter and dark energy.

[Joshua · Rating 5 out of 5]

At this point in time, big science is stuck in the slow lane. The glut of new theories and discoveries in high energy physics, astrophysics and cosmology which marked the twentieth century has hit a wall of foam and is barely inching its way through. The trouble plagued Large Hadron Collider won't be up to full power until the middle of the decade putting a hold on the search for the Higgs boson. String theory seems to be going nowhere and fusion power is forever twenty years in the future.

There is, however, one area of research which is advancing: the search for dark matter and dark energy in the universe. Evalyn Gates, a senior research assistant in astronomy and astrophysics and a cosmologist at the University of Chicago, has written a wonderfully accessible book on the subject.

Einstein's telescopes are massive objects in space, from large stars to whole clusters of galaxies, which act as magnifying lenses by bending the light from objects behind them as it travels to our telescopes. Using these gravitational lenses, we can observe and study far more distant parts of the universe than can even be seen by our best instruments alone. Dr. Gates' book is understandable and exciting with beautiful color plates and explanatory drawings. I recommend it to anyone who has ever asked the question, "what is the universe made of?"

[Aisha · Rating 4 out of 5]

A great and simple introduction to the topics of dark matter and dark energy.

[Valerie Book Valkyrie · Rating 4 out of 5]

4 Reader Friendly Stars
Written in a friendly tone & conversational style, no prior science knowledge of any kind is required. With easily relatable nonscience analogies, a few pictures & diagrams, some well defined acronyms, and a little self deprecating humor the author uses the first 3 chapters to lay down the basics needed to understand the contents of the remainder of the book. It's very good, a more relatable read than The Fabric of the Cosmos: Space, Time, and the Texture of Reality by Brian Greene, https://www.goodreads.com/review/show....

The deflection of light by massive objects (stars, galaxies, black holes) creates a lens (gravitational lensing) making it possible to map out the invisible-to-humans sector of the universe! This is the underlying principle upon which the operation of a powerful telescope, aka Einstein's Telescope, is based; no need to get "bogged down" with the minutia if that's not where it's at for you!

When exploring gravity the "real fun" begins when theories with more than four dimentions of space & time are included. The reading gets a little dense though and the theories are wonderfully ambitious & inventive, but in the end seem to come down to "anything is possible". Some of the theories regarding the matter/antimatter/dark matter are as rollicking as those postulated by Cjelli (aka Gently) in Dirk Gently's Holistic Detective Agency, which I recently read and highly recommend, https://www.goodreads.com/review/show....

Gently did omit the DARK ENERGY TASK FORCE (oh, no, a spoiler 🤫, where once again "science fiction" morphs into "science fact"), a U.S. agency indicated by the nomenclature "TASK FORCE" rather than "Agency" or "Bureau" which is more indicative of a British nomenclature. Established in 2005, this TASK FORCE consists of 13 scientists and is funded by the Dept of Energy, NASA, and the National Science Foundation! (You can read their one, and only, report here: https://arxiv.org/pdf/astro-ph/0609591
Wonder what the recently established Department of Government Efficiency (DOGE headed by Elon Musk) thinks of that?

[Pierre Menard · Rating 5 out of 5]

Questo saggio di Evalyn Gates, ricercatrice in astrofisica delle particelle e cosmologia, ora direttrice del Cleveland Museum of Natural History, è veramente un eccellente esempio di divulgazione scientifica di livello elevato. I temi affrontati sono le nuove frontiere della ricerca in astronomia e cosmologia raggiunte grazie al "telescopio" di Einstein, e la caccia ai due grandi interrogativi della materia oscura e dell'energia oscura.

Il libro prende l'avvio dalla constatazione che alla domanda "da che cosa è costituito l'universo?" possiamo dare una risposta precisa e circostanziata solo per il 5% circa dell'universo, la cosiddetta materia ordinaria, che il Modello Standard delle particelle elementari inquadra con estrema raffinatezza (per quanto non sia ancora completamente perfetto): il 23% è costituito da "materia oscura", di cui sappiamo poco – in sostanza che interagisce solo gravitazionalmente, ma non è osservabile –, e il 72% da "energia oscura", di cui sappiamo ancora meno, se non che è responsabile dell'espansione accelerata dell'universo da 5 miliardi di anni fa ad oggi. Se per l'uomo comune, questa ammissione di ignoranza al 95% può risultare frustrante, per lo scienziato - e per chiunque nutra un po' di curiosità per l'universo che ci circonda – è un invito a nozze, una sfida all'ingegno umano nel concepire nuove teorie fisiche e realizzare complessi esperimenti per interpretare la natura e svelarne i segreti. Estremamente stimolante è poi l'alta probabilità che per spiegare la materia o l'energia oscura sia necessario ricorrere a nuova fisica, ossia a qualcosa di completamente nuovo rispetto a quanto visto finora: una nuova forza con caratteristiche peculiari, nuove e molteplici dimensioni, forse il multiverso...

Dopo aver presentato il problema della costituzione dell'universo e il contesto scientifico, Gates discute brevemente la relatività generale e il modello del Big Bang, e propone una storia sintetica dell'universo. Passa poi a spiegare che cosa è l'effetto di lente gravitazionale su cui si basa il "telescopio di Einstein", scrivendo uno dei capitoli più affascinanti del libro (il quarto) e mostrando come la volta celeste sia animata da un caleidoscopio di illusioni ottiche incredibilmente utili alla ricerca in astronomia (*). Inizia poi la parte più complessa del libro: la ricerca della materia oscura, per la quale i teorici hanno già elaborato proposte articolate progressivamente sottoposte ai test sperimentali, che prevedono vari candidati (WIMPs e MACHOs, principalmente), e dell'energia oscura, per la quale le proposte teoriche non sono ancora coerenti e in grado di risolvere tutti i problemi. I capitoli finali dedicati all'espansione accelerata dell'universo sono forse un po' più ostici, ma credo riescano a rendere bene l'idea di che cosa significhi "conoscere" un fatto cosmologico, e ciò può suscitare interessanti riflessioni epistemologiche. Nel corso del libro Gates riesce a dare un'idea veramente esaustiva e dettagliata delle potenzialità delle lenti gravitazionali come strumenti di indagine: non soltanto la ricerca di materia ed energia oscura, ma anche la localizzazione dei pianeti estrasolari e l'identificazione dei buchi neri.

Il saggio risale al 2009, ed è ancora attuale, sebbene in questo ambito scientifico i progressi siano estremamente rapidi, quasi in espansione accelerata (come dice Gates nella prefazione, stiamo vivendo l'età dell'oro della cosmologia). Allora le onde gravitazionali erano ancora da confermare in modo diretto e alcuni dei progetti citati da Gates non erano ancora divenuti realtà, come la missione Kepler, che ha fornito nuove eccitanti scoperte già dal 2010. Il libro contiene molte figure esplicative e una bella collezioni di foto in bianco e nero davvero suggestive. Una ricca bibliografia, divisa per capitolo, permette al lettore curioso e all'esperto di documentarsi ulteriormente. Lo stile è chiaro e rigoroso, la prosa molto densa e mai noiosa, l'ordine espositivo ben congegnato, le note in numero contenuto. Bisogna ringraziare anche la traduttrice Elena Bernacchi, a cui va riconosciuto il merito di una traduzione adeguata al livello del libro e sempre perspicua. Credo sia necessario sottolineare due pregi dell'esposizione di Gates: la capacità di proporre esempi e analogie molto utili per capire alcuni passaggi difficili e la passione del ricercatore che sa comunicare il proprio entusiasmo anche ai non addetti ai lavori.

Ultima cosa. Per quanto Gates nella prefazione ci tenga a precisare che il saggio è accessibile a tutti, penso non siano da sottovalutare la complessità degli argomenti trattati e una certa conoscenza pregressa in ambito astronomico. In parole semplici, siamo un po' al di sopra della divulgazione generalista "stammi vicino e tienimi la mano" alla Piero Angela...

(*) come la suggestiva croce di Einstein.

Consigliato ai molatori di lenti (come Spinoza).

Sconsigliato agli agorafobici.

[Brie · Rating 3 out of 5]

The first title of this book really says it all, 'Einsteins Telescope' is definately the subject. The subtitle 'The Hunt for Dark Matter and Dark Energy in the Universe' is covered, but it is definately not the focus of this book.

Gates starts off with a brief overview of cosmology and physics, basically what you will need to know to continue reading. She then describes Einsteins telescope, which is gravitational lensing, and its many uses, some of which happen to be discovering the presence of dark matter and dark energy. She does well with this subject for the most part. I found some of her analogies a bit forced, but she generally did get the point across. It is quite interesting to find out that we really have no idea what dark energy is. There are at least some viable candidates for dark matter, but dark energy is another thing entirely.

If you are looking for a book about gravitational lensing, I would definately recommend this book. If you are looking for a book about dark matter and dark energy, I would look elsewhere. Perhaps Dan Hooper's Dark Cosmos: In Search of Our Universe's Missing Mass and Energy.

[Arthur Sperry · Rating 4 out of 5]

This is a really interesting book that describes how current research is being done and how it may change our outlook on the Universe. I recommend it to anyone interested in Astrophysics and Astronomy.

[James F · Rating 4 out of 5]

A very clear and simple introduction to the idea of gravitational lenses and the uses to which they are being put in observational astronomy. One of the most important questions in astrophysics and cosmology today is the question of what the universe is made of; the dark matter and dark energy which seem to make up the vast majority of the mass of the universe (unless our understanding of gravity needs to be revised), about which we know virtually nothing. Gates explains very well in popular, non-mathematical language the current state of the science and how gravitational lensing is being used to investigate the structure of the universe at large scales and try to provide some observational constraints on the theories. Up to date as of about seven years ago.

[Synthetic Vox · Rating 4 out of 5]

Very lucid writing of a difficult topic. However, as others have mentioned, not very much character in the writing. Some of the chapters seemed to be add-ons, particularly the black homes and planets piece and the dark energy piece. This is mostly a book about how gravitational lensing is used to understand space. It would have been nice to have more declarative summary statements at the beginning of chapters. Worth a read, but a little dry.

[Donovan · Rating 1 out of 5]

I read a bunch of reviews lauding this is an accurate and approachable work on modern physics. Accurate, yes. But drier than a bagel toasted in Hell. I got about forty pages in. Any recommendations for good books on this subject would be appreciated.

[Robert · Rating 3 out of 5]

Generally good. lost sometimes. But clarified very odd new things

[Bill Desjardins]

Good treatment, but uses a little too frequently over-simplified analogies to scientific concepts.

[Steve Schinke · Rating 4 out of 5]

Gravitational lensing was a concept that I was completely unfamiliar with, prior to reading this book. At least now I have a limited understanding of what it is and what a powerful tool it can be.

Overall, an excellent introduction to dark energy and dark matter, worth the time I spent reading it (which was longer than usual).

[Alan Parker · Rating 4 out of 5]

Nicely written guide to two of the biggest problems of contemporary physics. An easy read - no equations and plenty of good analogies to help understanding. The author is an expert, so we can trust her. Slightly out-of-date due to all the recent exciting discoveries of gravity waves by LIGO.

[Reader · Rating 1 out of 5]

The author should be fired by the publisher and academic degrees revoked. Title and cover has nothing to do with what is inside the book. Don’t waste your time reading such atrociously incorrect book.

[Jeremy]

Skip first 3 chapters. Good stuff about grav lensing. Super cool.

[Ray · Rating 5 out of 5]

Older book but worth reading

The author is an excellent explainer. The topic is truly interesting. The information was mostly new to me. Strongly recommended.

[Matthew Lundgren · Rating 4 out of 5]

A decent general overview on the ~2007 understanding of Dark Matter and Dark Energy.

[Hassan Ibra · Rating 5 out of 5]

This book is one of the reasons I am pursuing a graduate degree in physics. It is one of the best pop science books that I’ve read.

[Norman Edelen · Rating 4 out of 5]

Gravitational lensing, what it is, how we perceive it, and what it teaches us about the components of the Universe: matter, dark matter, and dark energy. Complex topics written for the lay reader.

[David · Rating 5 out of 5]

If you haven't kept up with recent work in astronomy (as I haven't) you'll will learn a great deal from this book. There has been a revolution in cosmology in the last ten years. Did you know that "ordinary" matter only makes up 5% of the universe? Did you know that astrophysicists are discovering that our understanding of the universe is far more limited than they thought only ten years ago? Did you know that the universe consists mostly of dark energy and nobody knows what it is? It's a very exciting time in astrophysics, and the author helps share that excitement with non-scientists.

This book does an excellent job of explaining physics, both astrophysics and particle physics in a clear way. The author is very good at using analogies from the ordinary world (marbles, ponds, expanding balloons) to explain difficult concepts. She's particularly good at explaining Einstein's general relativity theory, which is critical to most of the book.

This is one of the best popular science books I've read. My only quibble is that she repeats a lot of information. I believe she does it deliberately to reinforce concepts explained earlier in the book when they are needed again, but if you read the book in a short period of time, the repetition is slightly annoying.

This is not a book that you can read at a leisurely pace without paying attention. Even though the author does an excellent job explaining things, you must pay close attention.

[Matt Briar · Rating 5 out of 5]

Il sottotitolo del libro è "La caccia alla materia oscura e all'energia oscura", ma non spaventatevi. L'autrice, che dirige il Kavli Institute For Cosmological Physics di Chicago, arriva ad affrontare il più grande mistero della cosmologia moderna partendo dalle basi: la relatività einsteniana spiegata con un linguaggio semplice e ricco di paragoni ed esempi che permettono di capirne i concetti senza nozioni matematiche. Con un'eleganza espositiva rara, racconta una storia avvincente quanto quella di un romanzo. E alla fine, eccole, la materia e l'energia oscura, le più misteriose componenti dell'universo, in cui tutto è immerso (anche noi) ma che, paradossalmente, sono inosservabili. Oggi, però, un fenomeno previsto dalla teoria della relatività ci viene in aiuto: le lenti gravitazionali curvano lo spazio intorno a oggetti di grande massa, permettendoci di vedere ciò che vi si nasconde dietro e fornendoci informazioni finora impossibili da ottenere. Una lettura che ci trasporta ai confini dell'universo... letteralmente.

[Ryan Sanders · Rating 5 out of 5]

I thoroughly enjoyed sifting through the storied history on the search for dark matter and dark energy. She steers clear of some of the more technical aspects of gravitational lensing while managing to still convey the depth of the process. I would have liked more in the technical sense when it came to some of the descriptions involving physics but for the average reader this is a great starting point. My only critique is that the material in this book is slightly dated (not the difference between using solely Newtonian models in the current era outdated but some projects in the book mentioned to be "in planning phase" have either already launched, are currently launching, or have ended their life-cycles altogether.) and could use with a follow-up (Preferably by Dr. Gates herself!)

There is no section of the multiverse in which I did not give this book two thumbs up and any budding cosmologists should follow suit.

[Daniel Shawen · Rating 5 out of 5]

This is a great book, and the first one I have read from Evalyn Gates.

I previously had no idea that the Hubble Space Telescope was being so heavily used in order to find gravitational lensing, or the specific technology (interferometry) being used to do this.

Evidently, this particular heavy use of HST was something of an afterthought. In retrospect, it probably would have been prudent to design instruments for this express purpose. If this technique can be used to find gravitational lensing so easily, one wonders if a further refinement might also be possible to actually detect gravity waves? LIGO seems to have failed this function miserably, and part of the reason might actually be that not enough mass is there to be able to detect anything? (think ocean tides, Weber bars).

Anyway, this is a great book, and I highly recommend it.

[Joe · Rating 3 out of 5]

A most interesting book validating the use of space to create a magnifying glass into the past by useing the most prevelant matter in the universe, "DARK MATTER". The presence of dark matter is proved by its graviational effects on time and light and this book reminds us that nothing is impossible as we are just knocking at the door of the science of minor particles and the space-time continium.

Its worth the read and is written for the non scientist as other scientists have brought us up to date in an appreciation of "quantum mechanics" and partcle science. A manditory read for everyone.

[Lorileinart · Rating 5 out of 5]

Excellent...kept me reading for 2 long nights.
Gates perfectly illustrates where we (mankind) now stand regarding our understanding of dark matter and dark energy. I could go on about that, but who's really going to care or understand? (if you DO, by all means, msg me!)
The unexpected strength of this book, however, is the author's ability to illuminate relativity in a very accessible way. Whatever your understanding of Einstein's theories, you will come away with a greater sense of what they mean and how they affect our future.
Good brain candy, this one.

[J. D. · Rating 5 out of 5]

As a layman who drew some esthetic comfort from the Big-Bang/Expansion/Contraction/Big-Crunch cosmological model, I have read reports, in the last ten or fifteen years, of the discovery of expansion-acceleration with mixed feelings. However, if one has to receive bad news, it should be as expertly and concisely delivered as possible -- and the author, an experienced reasearcher, has filled that need admirably. I can't recommend this book highly enough.

[Jean-claude · Rating 5 out of 5]

This is an engrossing overview of gravitational lensing and the associated physics of dark energy and dark matter. Often books like these gloss over theory but Gates does a fantastic job of presenting enough evidence in sufficient detail to make it interesting. The fact that we don't understand what makes up most of the universe is pretty humbling and thought provoking. It certainly made my trip to the west coast seem a lot shorter.