While I am glad I read this book, I found the author's many chatty comments gratuitous, irritating, and condescending. The material seemed a bit stretched to me, as if to consume more pages. Fuller discussion of a few things the author apparently deemed beyond our ken would have been a more profitable use of pages. Adding Martin Rees as a co-author when all he wrote was the forward mislead me, but that was probably my fault for not reading the fine print. I bought this on the recommendation of a trusted friend who listened to it as an audio book. Maybe the author's "voice" worked better in that medium. For the price of the hard cover I bought I expected a better treatment of the subject. But some of the author's analogies were quite good by way of explaining, and that seems to be his strength. I'd add an extra half star for that element if I could. I usually read these kinds of books with impatient gusto in a couple of days, but it took me well over a week to finish this one.
4,0 su 5 stelleThe Story of Gravitational Wave Detection
12 settembre 2017 - Pubblicato su Amazon.com
In another book review I said that it’s easy to tell the difference between a book written by a scientist and a book written about science by a professional writer. This is the latter. Nothing wrong with that, of course — you trade the first-hand account of the scientist involved in a field for the third person narrative, by someone whose trade is writing and telling a good story.
Really, it’s a choice for the reader. Do you want to focus on the science or on the story? Of course, the author tries to do both, but, in this case, it’s the story that takes precedence, with sometimes explicit time-outs to explain the science (e.g., a chapter on the Big Bang).
The core of the book is the story of the first confirmed detection of gravitational waves, generated by colliding black holes, in September, 2015, by LIGO (Laser Interferometer Gravitational-Wave Observatory) in Hanford, Washington and Livingston, Louisiana.
Schilling takes us through the history leading up to gravitational wave detection, from their prediction in general relativity through early attempts to detect their presence, and on to the surprisingly quick detection once LIGO came online. He takes some pains to explain both the history — gravitational waves were speculated upon prior to Einstein’s publications — and some of the physics behind them.
Exactly what a gravitational wave is requires some explanation. Typically, waves are explained through analogy — a rock falls into a pond, causing waves to propagate through the pond’s water. But the analogy falls short. There is no medium like the water in the pond — the waves are ripples in space, or spacetime, itself. The ripples don’t propagate through space, the waves are waves in space itself — expansions and contractions in spacetime caused by gravitational events, like a collision between black holes. It doesn’t take a cataclysmic event like a collision of black holes to create gravitational waves, but it does take an event of that magnitude to trigger current detection technology.
Schilling’s story captures the drama of the detection, but he also, rightly I think, tells the story of how the detectors were built. Gravitational waves were theoretical. No one had observed them. They were predicted, and their effects were observed. But to actually detect them was going to take a serious investment of time and money, not to mention the careers of the scientists involved. Getting funding for detecting something that may or may not exist, and may or may not be detectable with the planned instruments — that’s not an easy thing to go to funding sources with, in the United States or elsewhere.
And what is the payoff?
Confirming a principal prediction of general relativity is a huge payoff for scientists. Knowing that our account of the universe is confirmed at such a foundational level not only increases our confidence in that account. But it also sets constraints around where we have to go next, in the looming problem of reconciling quantum theory with general relativity. Some scientists expected, and may still expect, gravitational waves to expose problems in relativity theory that will lead us to that reconciliation. So far, general relativity is left standing in its predictions.
Maybe more than anything else, though, gravitational wave detection presents us with what Schilling describes as a kind of additional sense modality. Gravitational waves are a wholly different phenomenon from electromagnetic radiation, sound waves, or any other medium through which we can observe what happens in the universe. When we opened our extended senses to radio, microwave, and other non-optical parts of the electromagnetic spectrum, we detected things that were completely unknown, like the cosmic microwave background legacy of the big bang. The ability to detect gravitational waves doesn’t just open another part of the same spectrum, but a completely different medium for observation. As Schilling says, it’s probably what will surprise us that will turn out to be most valuable.
And in fact observing gravitational waves has some distinct advantages over observations of electromagnetic radiation. Gravitational waves are not absorbed or reflected by dust or gas — emissions from their points of origin travel unhindered to our detectors. And some currently poorly understood phenomena, like dark matter and dark energy, have especially interesting gravitational properties and effects, maybe best studied via gravitational wave astronomy, complementing more traditional astronomy. Schilling teases some of those possibilities in his final chapter.
And gravitational wave detection may help us to understand some of the missing pieces in the story of the universe’s evolution from the Big Bang. "Primordial black holes” may be detectable via gravitational waves and give us some clues to those missing pieces.
The universe is actually heavily populated with natural gravitational wave detectors — pulsars. Pulsars emit highly regular, fast pulses of radiation — their regularity, fast pace, and strength of signal make them natural clocks. If there is a change in the period of a pulsar’s signal, something has caused it, and the something might be the stretching or contracting of space via gravitational waves.
Observations of changes in pulsar timing via radio telescopes are one active area for gravitational wave detection.
Schilling’s later chapters look forward to other sorts of detectors, extensions of the design behind LIGO and the similar Virgo detector in Italy. These include space-based detectors like the European Space Agency’s long-planned LISA, and an underground detector, KAGRA, in Japan, as well as a LIGO-like detector in India. An even more ambitious ground-based detector called ET (Einstein Telescope) is also in planning stages, and an American project, Cosmic Explorer, with yet greater sensitivity to detect fainter and fainter gravitational waves is in idea-stage.
If you’re looking to catch up on the story of gravitational waves, and maybe go on to more depth on the science itself, this is a great place to start. Schilling is a good writer, he knows enough about the science to explain it for a relatively non-technical audience, and he knows how to tell the story.
5,0 su 5 stelleAstonishing Book of Wondrous Stories!
23 settembre 2017 - Pubblicato su Amazon.com
Simply Astonishing! Every young student of Physics or Astronomy should leap at the chance to read this one! What a captivating inspiring story! I raced through the first 100 pages in a single sitting, then rationed myself to a single chapter per day to make the book last longer. I found that every time I picked it up to read some more, I was drawn in deeper and deeper. Each of the dozens of stories told in this book are woven together to support the main story, but with each side trip (to things such as Pulsars, the inner workings of Neutron stars, Weber bars, Carl Sagan's Apple Pie, BICEP2, Milisecond Pulsars, Frame Dragging, the anomalous precession of Mercury just to name a few) I'd reluctantly close the book, but my mind simply couldn't shut off after putting it down, and I'd be anxiously awaiting the next chance I'd have to spend another 30-minutes in this treasure trove of astonishing facts, and would find myself diving deeper into many of the topics Schilling brought up. Schilling writes with passion for the subject, and though I consider myself well-versed in Astronomy and Physics, there were so many fascinating nuggets in this story, that it was easy to be astonished anew! Highly recommended!! GREAT BOOK!!
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