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

In 1970 many physicists and cosmologists thought that we would soon know all the basic physical principles governing the universe. The Big Bang was largely confirmed by cosmic background radiation and we knew about expansion. Quantum mechanics ruled the small while the large was the domain of relativity. The two theories weren't linked yet, but it was merely a matter of a little more time and work. Success would bring an explanation unifying the four fundamental physical forces of the universe: Electromagnetism, the strong force (binding protons and neutrons together in atomic nuclei), the weak force (governing certain kinds of particle decay) and gravity. Surely the "theory of everything" was not far off.

Wrong. Observations in 1970 revealed that gravitational motions of gas clouds in the Andromeda galaxy were occurring at speeds far greater than the entire observed mass of that galaxy could account for. Similar problems detected in the 1930's involving motions of entire galaxies had long been disregarded. Soon other observations confirmed that so-called "ordinary matter" is insufficient to account for observed gravitational effects in the cosmos. Thus the universe must contain huge amounts of "dark matter," that we cannot observe and the composition of which we do not know (it is not made of the particles that constitute ordinary matter).

Then in 1998 reports of observations of distant supernovae revealed that the expansion of the universe was not slowing, as would be expected from long-term effects of gravity, but was instead accelerating. Something was overcoming the gravitational power of all of the matter in the universe. The acceleration, moreover, has not been present from the Big Bang on. For billions of years the speed of expansion slowed. Then, about 5 billion years ago, acceleration began. Obviously energy--a lot of it--- was required to explain these phenomena. This is "dark energy." We cannot detect it and currently know almost nothing about it.

Today scientists believe that 5% of the universe consists of "ordinary" [observable] matter, 23% of "dark" matter and 72% of "dark energy." So in about 40 years we have gone from thinking that we knew almost everything about the essentials of cosmology to actually knowing something about only 5% of the universe, very little about an additional 23% and almost nothing about 72% of it.

But author Gates (herself a theoretical physicist by training) is energized rather than discouraged. In this book she discusses fully the problems noted above (and more), explains their significance and outlines in detail the methods that are being used or planned to attack them. The book's title comes from one of the major investigational tools: Use of relativistic spacetime itself as an observational device. General relativity teaches that the presence of mass warps spacetime. As light travels through the universe it follows a curved path through these "dimples" in spacetime. Because these warps bend light, it is as if a giant lens has been dropped into space, magnifying and displacing light from more distant sources behind it. When Earth is aligned with such a "lens," it allows us to detect and analyse vastly more distant light sources otherwise not observable. This is useful in searching for dark matter because it allows "maps" to be made showing where dark matter exists in distant sources. Gates does an outstanding job of describing this and other significant techniques for making these inquiries, noting the strengths and weaknesses of each method in investigating certain types of phenomena. The use of different techniques should permit the capture of disparate forms of data and lead, we hope, to detection and analysis of dark matter and dark energy.

This is an exciting time for cosmology and physics. The results of these inquiries will, at the least, radically change our view of the cosmos. Depending on results, it may be necessary to modify Einstein's theory of general relativity to account for the observed actions of gravity in the universe. Gates is also quite good at conveying the excitement now animating these scientific fields. Her writing is clear and readable, if seldom compelling. Overall this book is recommended for anyone interested in today's leading cosmological puzzles.

Astrophysicist Evalyn Gates brings the world of gravitational lensing and the search for the unknown constituents of the Universe to the reader in her book Einstein's Telescope. Gates has spent many years in this search, and this book is an excellent introduction and advanced discussion, laying the foundation for the work she (and others) will do over the next decade to unmask some of the great mysteries in cosmology and astrophysics.

Gates introduces a brief history of how scientists came to understand that dark matter and dark energy had to be part of our Universe in order to explain a few basic observations. Once she has offered the reader a framework for why we need to look more deeply at the way our Universe appears, Gates explains just what causes the "Einstein's Telescope" effect. This fascinating technique involves gravitational lensing of distant objects by massive objects sitting closer to the Earth. Often, the lenses are clusters of galaxies, and through the process of lensing more distant galaxies, we can learn how much mass is acting on the light of the distant sources, giving us insight into where dark matter may reside and exactly how it interacts with ordinary mass.

The book explains various theories of dark matter, primarily MACHOs and WIMPs, offers glimpses at the even more mysterious dark energy, for which there are no shortage of wild theories, and eventually goes deep into the cosmic web that may hold clues to the earliest formation of galaxies.

Later parts of the book, which may well be the strongest in what is a very solid presentation, describe the multiple experiments ongoing and various theories currently being formulated. Gates explains how these new techniques and new opportunities may shed light on our understanding of the Universe, its beginnings, and its evolution. Anyone who wants to understand the amazing findings that have begun to trickle out of this astrophysical work (and which will continue to become available over the next decade or two) will find strong explanations by Gates herein. This section alone makes the entire book worth reading for me.

Gates is an excellent writer who refuses to waste the reader's time. She has a solid grasp of her subject, and better, is highly successful at making the complex scientific concepts approachable by most any reader. Tons of great cutting-edge science is in store for a reader of this book, and those with a strong knowledge of cosmology and astronomy can still find much to learn and enjoy in Telescope. A handful of excellent images and illustrations are included in the hardback edition which offer the reader tantilizing, beautiful references to Gates' material, including real photographs of some fantastic shots of gravitation lensing.

For any science reader, and most especially those who enjoy space sciences, this book is highly recommended as a solid effort to update the reader's understanding of current astrophysical efforts and approaches to this fascinating field. While much of the science is complex, the style makes it easy to digest, without watering down the concepts. Four stars.

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"What we have learned [about our Universe] is amazing. The Universe is 13.7 billion years old, it has a temperature of just under 3 degrees above absolute zero, and its spatial geometry is flat. The enormous expanse of space that we can see today, filled with hundreds of billions of galaxies, began as an intensely hot, almost infinitely dense soup of energy that has expanded and cooled since the beginning of time and space. Space itself is expanding in a great cosmic stretch that has recently begun to kick up a notch--the Universe is accelerating. And it is dark. The cosmic inventory is dominated by dark energy (72%) and dark matter (23%) [both of which we can't see]; normal matter, which comprises everything we [can see and] have ever been able to hold in our hands or examine with our instruments, comes in a distant third, contributing only about 5% of everything that is."

The above comes from the epilogue of this well-written, very informative book by Dr. Evalyn Gates, Assistant Director of the Kavli Institute for Cosmological Physics and a Senior Research Associate at the University of Chicago.

So what is this book about? As might be deduced from the above quotation, it's about the dark side of the Universe--dark matter, dark energy, even black holes.

Dark matter is the hypothetical matter that holds the galaxies together. WIMPs (Weakly Interacting Massive Particle), mentioned in this review's title, are one of the leading candidates for a type of dark matter. Dark energy is the hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the Universe. (A black hole in general relativity is a region of space in which the gravitational pull is so powerful that nothing, including light, can escape its pull. Black holes can't be seen directly.)

As mentioned, dark matter and dark energy can't be seen. How are astronomers to look for these things they can't see? That's where "Einstein's telescope" comes in.

Technically, Einstein's telescope is called "gravitational lensing." This book explains how it works. (Note that gravitational lensing is one of the predictions of physicist Albert Einstein's Theory of General Relativity.)

Einstein's telescope or gravitational lensing can be used to solve the biggest mysteries of the Universe by using ordinary luminous matter to discover dark matter and its distribution (as well as other dark objects such as black holes and objects too far away to be seen by our best telescopes such as other Earths). This discovered dark matter itself can be used to probe for the imprint of dark energy (and the very structure of space and time).

The final chapter is a fantastic discussion of "gravity waves" (or gravitational waves). A gravity wave is a fluctuation in the curvature of space-time which propagates as a wave, traveling outward from the source. Predicted again from Einstein's Theory of General Relativity.

This book is quite accessible. No prior knowledge of science of any kind is assumed. Those with a science background will find that the first three chapters cover familiar ground.

Throughout the book are helpful black and white illustrations (pictures, graphs, etc.). As a bonus, there is a section of ten beautiful full-color photographs.

Finally, my only minor problem with this book is that I would have appreciated in having all new terms introduced in the main narrative listed (with definitions) in a glossary.

In conclusion, this is an extraordinary and captivating book!! And don't worry! You don't have to be MACHO to read it. (MACHO stands for Massive Astrophysical Compact Halo Object.)

(first published 2009; preface; acknowledgements; glossary of acronyms; 12 chapters; epilogue; main narrative 270 pages; notes; illustration acknowledgments; index; about the author)

<<Stephen Pletko, London, Ontario, Canada>>

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