Extraterrestrial: The First Sign of Intelligent Life Beyond Earth

by Avi Loeb

Harvard’s top astronomer lays out his controversial theory that our solar system was recently visited by advanced alien technology from a distant star.

In late 2017, scientists at a Hawaiian observatory glimpsed an object soaring through our inner solar system, moving so quickly that it could only have come from another star. Avi Loeb, Harvard’s top astronomer, showed it was not an asteroid; it was moving too fast along a strange orbit, and left no trail of gas or debris in its wake. There was only one conceivable explanation: the object was a piece of advanced technology created by a distant alien civilization.
 
In Extraterrestrial, Loeb takes readers inside the thrilling story of the first interstellar visitor to be spotted in our solar system. He outlines his controversial theory and its profound implications: for science, for religion, and for the future of our species and our planet. A mind-bending journey through the furthest reaches of science, space-time, and the human imagination, Extraterrestrial challenges readers to aim for the stars—and to think critically about what’s out there, no matter how strange it seems.

Genres: Science, Nonfiction, Space, Astronomy, Aliens, Physics, Audiobook

240 pages, Hardcover

First published March 15, 2021

About the author

Abraham (Avi) Loeb is the Frank B. Baird, Jr., Professor of Science at Harvard University and a bestselling author (in lists of the New York Times,Wall Street Journal, Publishers Weekly, Die Zeit, Der Spiegel, L'Express and more). He received a PhD in Physics from the Hebrew University of Jerusalem in Israel at age 24 (1980-1986), led the first international project supported by the Strategic Defense Initiative (1983-1988), and was subsequently a long-term member of the Institute for Advanced Study at Princeton (1988-1993). Loeb has written 8 books, including most recently, Extraterrestrial (Houghton Mifflin Harcourt, 2021), and about 800 papers (with an h-index of 114) on a wide range of topics, including black holes, the first stars, the search for extraterrestrial life and the future of the Universe. He had been the longest serving Chair of Harvard's Department of Astronomy (2011-2020), Founding Director of Harvard's Black Hole Initiative (2016-2021) and Director of the Institute for Theory and Computation (2007-present) within the Harvard-Smithsonian Center for Astrophysics . He is an elected fellow of the American Academy of Arts & Sciences, the American Physical Society, and the International Academy of Astronautics. Loeb is a former member of the President's Council of Advisors on Science and Technology (PCAST) at the White House, a former chair of the Board on Physics and Astronomy of the National Academies (2018-2021) and a current member of the Advisory Board for "Einstein: Visualize the Impossible" of the Hebrew University. He also chairs the Advisory Committee for the Breakthrough Starshot Initiative (2016-present) and serves as the Science Theory Director for all Initiatives of the Breakthrough Prize Foundation. In 2012, TIME magazine selected Loeb as one of the 25 most influential people in space and in 2020 Loeb was selected among the 14 most inspiring Israelis of the last decade.

Reviews

[Yun · Rating 2 out of 5]

The Hawaiian word 'oumuamua . . . is loosely translated as "scout." In its announcement of the object's official designation, the [IAU] defined 'oumuamua slightly differently, as "a messenger from afar arriving first." Either way, the name clearly implies that the object was the first of others to come.

Holy cow, I'm not afraid to say this freaked me out a bit! Could evidence of intelligent life have really whizzed by our Sun a few years ago and we were none the wiser?

In the Fall of 2017, an object raced through our solar system and quickly left. It was traveling so fast that it could only have come from afar. Extraterrestrial: The First Sign of Intelligent Life Beyond Earth lays out all the data we have regarding this interstellar visitor, and makes a compelling case for why all the facts and anomalies point to this being a piece of advanced alien technology.

This completely blew my mind! It was utterly fascinating (and also kind of freaky) to follow along as each piece of data was presented and then matched up with the alien technology theory. And it seems academically sound and wholly plausible.

So why the low rating? Well, that discussion is just a very small part of this book. In the thirteen chapters, only chapters 1 and 3 were totally dedicated to 'Oumuamua.

And here's the crux of the issue: all the information, data, and facts collected regarding 'Oumuamua can be squeezed into a long article. So to make a book out of it, the author really had to expand upon the topic. It doesn't help that his expansions are heavily pedantic, often turning concepts the layman can understand into complex technical jargon that only those in the field could wade through.

To further expand and turn this into the length of a book, the author filled the majority of this book with information about his family and how he grew up, his professional career, summaries of pretty much every paper he has written that is even remotely relevant, every person he has worked with, his personal views on philosophy and science, and numerous rants against the scientific community's inability to consider new ideas.

It feels like the author decided to use this book as his personal soapbox and as a chance to show off how accomplished he is. Which is silly because I already believe he is someone worth listening to and his theory has plausibility, hence why I'm reading this.

If you're interested in 'Oumuamua, I obviously don't recommend this book. Instead you can just look up some articles or videos, get the gist of it, walk away slightly freaked out like I am, and save yourself several hours.

[Manny · Rating 4 out of 5]

On October 19 2017, astronomers at an observatory in Hawaii noticed an unusual fast-moving object about twenty million miles from Earth. This soon became known as 'Oumuamua, a Hawaiian word meaning something like "scout". 'Oumuamua's orbit could easily be plotted, which showed that it came from outside the Solar System and was heading back into the interstellar depths. No one could figure out what it was. It looked a bit like an asteroid, but people discovered that its orbit was changing, indicating that some force other than gravity was acting on it. Comets do this; as you might remember from Armageddon and Deep Impact, the heat of the Sun vaporises frozen gases to form natural rocket engines, the exhausts from which turn into the comet's tail. But 'Oumuamua had no visible tail.

Further observation made 'Oumuamua look even odder. Not only was there a force acting on the object, that force was being smoothly applied and was inversely proportional to the square of the object's distance from the Sun; jets from comets are not smooth, but stop and start haphazardly. Also, the brightness of the object varied according to a regular eight hour cycle. At maximum, it was about ten times brighter than at minimum. That seemed to show it was rotating, and also that it was very far from spherical. Either it was an extremely elongated cylinder or else a flat disk. Detailed models suggested that a disk shape gave the best fit to the data. Unfortunately, it was impossible to get a detailed picture. By the time it was picked up, 'Oumuamua was already well on its way back into the outer darkness. All you could see was a point, and after another eleven days it could no longer be tracked.

Whatever could 'Oumuamua be? After a while, the mainstream hypothesis was that it was an chunk of solid hydrogen, a "hydrogen iceberg". Hydrogen wouldn't leave a visible trail when it boiled off, but many questions remained. Hydrogen icebergs are supposed to exist in certain distant regions of interstellar space, but it was hard to explain how one could have travelled all the way to our Solar System without evaporating en route. It was even harder to explain why it had such an unusual shape, or how the hydrogen boiled off to produce such an even thrust. A more daring hypothesis was advanced by the author of this book: 'Oumuamua was an alien spaceship fitted with a lightsail. That got the attention of the world's press for a while, but the scientific community refused to take the idea seriously. With all its faults, they preferred the hydrogen iceberg theory.

This book is an attempt to reopen the case, which has been quietly filed away as "just one of those weird things". Avi Loeb, author and the main proponent of the alien spaceship theory, is about as far from being a UFO crank as it's possible to get. He was the Chair of Harvard's Department of Astronomy for ten years and has an outstanding publication record. He comes across as engaging, modest, mild-mannered and completely sane. He says many times that he's disappointed his colleagues won't do their duty as scientists and simply follow the data where it leads. The problem, as every member of today's scientific community knows, is that most people can't afford to follow the data; they need to follow the grant money. Pursuing ideas that sound cranky or are simply unfashionable may get you labelled unfundable and end your career.

Loeb says, politely but firmly, that this has created a ridiculous situation. It's safe to investigate the notion that the universe has ten dimensions, when there isn't a single piece of evidence to show that six of them exist; but it's not safe to investigate the idea that a mysterious object in the sky could be an alien spaceship, despite the fact that there is a great deal of supporting evidence. String theory is fashionable, alien civilizations are not. That's all there is to it. We don't know whether there are any alien civilizations: there's no strong argument for or against. If we aren't prepared to look at possible evidence even when it's thrust under our noses, we'll never find out. The question is, to put it mildly, of general interest. Loeb elaborates on these themes.

I found the book utterly captivating and read it in a day. The only criticism I'd make is that I'd have liked more on the details of the 'Oumuamua data and less polemic against the scientific establishment. Two questions in particular kept occurring to me. First, I couldn't visualise how the lightsail scenario worked: if the lightsail is pointing away from the Sun, which I thought it had to do, around which axis is the spaceship supposed to be rotating in order to get the observed changes in brightness? I'm guessing someone has mocked up an animated simulation, and it would have been great to get a link. Second, has anyone been able to figure out where 'Oumuamua is headed after looping round the Sun? Using a lightsail to apply thrust would imply that it could have been making a course correction. If it looked like it was moving towards a nearby star, that would support the spaceship hypothesis. But I'm nitpicking. Read this book, then complain to your Congressman or MP that the scientific funding model needs revision. Fashion is great on the catwalk, it shouldn't be this important in the physics department.
____________________

PS My local fashion expert tells me that fashion is bullshit on the catwalk too. I stand corrected.

[Claudia · Rating 2 out of 5]

I believe Mr. Loeb suffers from lack of praise or/and credit. Despite his achievements and titles, and I quote him here: "At the time of this writing, I serve as chair of Harvard University's Department of Astronomy, founding director of Harvard's Black Hole Initiative, director of the Institute for Theory and Computation within Harvard-Smithsonian Center for Astrophysics, chair of the Breakthrough Starshot Initiative, chair of the Board on Physics and Astronomy of National Academies, a member of the advisory board for the digital platform Einstein: Visualize the Impossible from the Hebrew University of Jerusalem, and a member of the President's Council of Advisors on Science and Technology in Washington, DC", I think he tries to convince us of his credibility, even if he says at some point that he doesn't care what others think of him. But this is the only explanation I have for this novel being some sort of autobiography and bibliography at the same time. And there are a lot of paragraphs like the above one. Don't get me wrong, it's a very impressive career, and I bow to that; he has all my respect. It's just that he's trying too hard to convince us he is worth believing, and it seems rather boastful . I don't think anyone would have put his words into question, but who knows. *

When a science book gets my interest, first thing I do is look out the author if the name is not familiar, as I think most readers do, right? So, when I start reading the book, I know who the author is, what he does and what are his achievements; I do not need to read all this info in the book.

The other half touches the subject in the title, and in particular, 'Oumuamua, the interstellar object whose visit in the neighborhood sparked a lot of debates and hopes. He thinks it's an artefact created by another civilization, and seems to me he advocated his case well enough. * *

But then again, he laments a lot about most of his field colleagues being skeptical, and also about the lack of funds and interest about extraterrestrial life research.

Well, my interest was in 'Oumuamua, the rest I can't say I care too much about; there is a lack of funds in much more pressing earthly domains than searching for ET, as much as I would like for their existence to be proved.

Another thing that bothered me is his dislike of science fiction "when it violates the laws of physics", because he worries "that sensationalized depictions of aliens have led to a popular and scientific culture in which it is acceptable to laugh off many serious discussions of alien life even when the evidence clearly indicates that this is a topic worthy of discussion; indeed, one that we ought to be discussing now more than ever." I think he's wrong: SF with aliens or which transcend the laws of physics, as we know them, are only raising our curiosity about the vastness of this universe and its wonders; there is nothing to laugh about.

Bottom line: without so much self-praise and complains, it would have easily been a 4 stars reading for me, because the author writes with passion and there are some really interesting topics in the book. In this form, unfortunately, it wasn't.


* Maybe he thought about Haim Eshed, who was director of space programs for Israel Ministry of Defense for nearly 30 years, former chair of the Space Committee of the National Council for Research and Development for the Ministry of Science, Technology and Space and a member of the steering committee of Israel Space Agency, and who in "The Universe Beyond the Horizon – Conversations with Prof. Haim Eshed” by Hagar Yanai, is disclosing that aliens do exist and we are in contact with them for years?

https://m.jpost.com/omg/former-israel...

As far as I know, this book was not translated (yet) in English. If anyone knows if/when it will be, please let me know; I can't wait to read about the underground base on Mars and how the Galactic Federation stopped Trump to reveal their existence to us...

* * A few days ago, a new paper was published and it looks like 'Oumuamua is not an alien artefact, after all:
https://phys.org/news/2021-03-scienti...

https://www.theguardian.com/science/2...

Interesting to see if we will ever know for sure what it is.

[Krista · Rating 5 out of 5]

If evidence of extraterrestrial life appeared in our solar system, would we notice it? If we were expecting the bang of gravity-defying ships on the horizon, do we risk missing the subtle sounds of other arrivals? What if, for instance, that evidence was inert or defunct technology — the equivalent, perhaps, of a billion-year-old civilization’s trash?

On October 19, 2017, astronomer Robert Weryk at the Haleakala Observatory in Hawaii discovered the first interstellar object ever detected in our solar system — a “wildly anomalous object” that would eventually be named ‘Oumuamua (Hawaiian for “scout”, or more poetically, “a messenger from afar arriving first”) — and although this object was only detected as it was exiting our Earthbound field of vision (racing toward and then beyond the sun), scientists were able to observe ‘Oumuamua for eleven days before it disappeared; gathering data that matched no previously known celestial object. The majority of scientists filed ‘Oumuamua away as a weird comet or asteroid (that behaved like no known comets or asteroids) but Dr. Avi Loeb — the chair of Harvard University’s Department of Astronomy, founding director of Harvard’s Black Hole Initiative, director of the Institute for Theory and Computation within the Harvard-Smithsonian Center for Astrophysics, chair of the Breakthrough Starshot Initiative, chair of the Board on Physics and Astronomy of the National Academies, etc., etc. — came up with a competing theory: All of ‘Oumuamua’s strange composition and erratic movement could be accounted for if it were a piece of technology manufactured by some nonhuman intelligent lifeform. This theory, despite explaining the anomaly simply as per Occam’s Razor, met with official resistance and dismissal, and Extraterrestrial:The First Sign of Intelligent Life Beyond Earth seems to be Loeb’s longform explanation of the facts, how the data fit his theory as proof of extraterrestrial intelligence, and ultimately, why the mainstreaming of this theory matters. Loeb’s writing is clear and easy to understand, certainly persuasive to a lay reader like me, and as his first love was Philosophy, Loeb is able to connect the arrival of this extrastellar object to all the big questions facing us Earthlings. This is everything I love, told engagingly, and I recommend it highly. (Note: I read an ARC through NetGalley and passages quoted may not be in their final forms; quotes selected primarily to demonstrate the author’s style, not as an overview of his theory.)

Some of the resistance to the search for extraterrestrial intelligence boils down to conservatism, which many scientists adopt in order to minimize the number of mistakes they make during their careers. This is the path of least resistance, and it works; scientists who preserve their images in this way receive more honors, more awards, and more funding. Sadly, this also increases the force of their echo effect, for the funding establishes even bigger research groups that can parrot the same ideas. This can snowball; echo chambers amplify conservatism of thought, wringing the native curiosity out of young researchers, most of whom feel they must fall in line to secure a job. Unchecked, this trend could turn scientific consensus into a self-fulfilling prophecy.

I don’t actually want to go over what made ‘Oumuamua so anomalous — or how its anomalies can be easily explained by Loeb’s theory — but I do want to note what Dr. Loeb has to say about conservatism in academe and how it stifles original thought (even suppressing it a la Galileo). He notes in several places that there is plenty of Physics Department money and brainpower devoted to studying theories such as supersymmetry and multiverses — despite there being zero proof (yet) that either actually exists — and scientists would rather propose pure hydrogen comets or “fluffy cloud objects” — despite there being zero proof (yet) that either actually exists — in order to explain ‘Oumuamua’s eccentricities than entertain Loeb’s theory that it behaved exactly like a pancake-shaped, metallic solar sail (could be a buoy that our solar system passed by and disturbed or a wandering piece of space junk). The gatekeepers of the world’s large and expensive observatories decide who gets to use them and for what purpose (as they must), but with the SETI project treated as fringe science, and Loeb determining that SETI’s concentration on searching for radio transmissions is probably flawed anyway, it’s frustrating to see that even compelling proof of intelligent extraterrestrial life isn’t sparking a pursuit of space archaeology as Loeb has argued for (“Similar to archaeologists who dig into the ground to learn about, say, Mayan society, astronomers must start searching for technological civilizations by digging into space.”) And because Loeb’s first interest was Philosophy, I was drawn to his explanations (beyond the pursuit of scientific advancement) of why acknowledging the existence of extraterrestrial life matters:

In astronomy, we realize that matter takes new forms over time. The matter we are made of was produced in the heart of a nearby massive star that exploded. It assembled to make the Earth that nourishes plants that feed our bodies. What are we, then, if not just fleeting shapes taken by a few specks of material for a brief moment in cosmic history on the surface of one planet out of so many? We are insignificant, not just because the cosmos is so vast, but also because we ourselves are so tiny. Each of us is merely a transient structure that comes and goes, recorded in the minds of other transient structures. And that is all.

I enjoyed Dr. Loeb’s clear writing style and the personal details that he shared — I was as interested in his daughter meeting Stephen Hawking as I was interested to learn of Loeb’s Jewish grandfather fleeing 1930’s Germany — and I was intrigued by the hope for the future of humanity that the discovery of ‘Oumuamua represented for him. Our best future is probably out in space, and to get there, we need the search for extraterrestrial life not to be dismissed as fringe science, for young scientists not to be lockstepped towards conservative areas of study, and for the population at large to be informed of and become excited by ideas that could unite us all in a shared vision of a better future. I loved the whole thing.

[Troy Tradup · Rating 2 out of 5]

I may be entering one of those phases where I'm simply dissatisfied with everything I read for no particular reason. OR, perhaps this author's insistence on his own importance just became annoying as hell when stretched across two hundred pages.

Loeb's writing style was quite off-putting for me, and there were numerous instances where I felt I was reading his C.V. rather than the story of the first interstellar object we've ever observed passing through our solar system.

Ostensibly the book is Loeb's argument that his hypothesis for 'Oumuamua being a manufactured object rather than a natural one -- an extraterrestrial lightsail, perhaps -- is as valid as any other based on the evidence, and thus worthy of serious scientific consideration. Too often, however, the book feels more like one long whine of: "Why are the other scientists being so mean to me?"

I should probably admit that I fully believe there is other intelligent life "out there" (although I'm less certain if there's any here on Earth). So this book didn't have to work too hard to make me believe the extraterrestrial-origin hypothesis worthy of examination. I get Loeb's frustration with the scientific community. "It is an exotic hypothesis," he writes. "But it is no less exotic than the other hypotheses that have been proposed to explain the outlier characteristics of 'Oumuamua."

Probably the most convincing argument against Loeb (and I say Loeb specifically here rather than his hypothesis) is the fact that he was actively working on a project to develop lightsails of our own when he published his theory about an extraterrestrial version of the same technology. One interviewer cited the proverb: "Whoever has only a hammer will see nothing but nails."

Personally, I would have been satisfied with a much shorter, sharper version of Loeb's hypothesis and the evidence he cites to support it -- an article in Scientific American, for example. He even writes a great close to that hypothetical article halfway through this book:

"The lightsail hypothesis opens up a world of possibilities -- unlike the comet hypothesis, which closes them off. The fact that scientific consensus strongly favors the more conservative and restrictive of these two possibilities says less about the evidence than it does about the practitioners and culture of science itself."

[Leo · Rating 4 out of 5]

This wasn't quite what I expected. It had a more serious and more calm approach to this topic. I've read a few books and seen a few documentarys about aliens and they often sounds like some kind of movie plot that it's hard to wrap a logical thought around. This felt a lot more like an serious non fiction more, which I think it's definitely was intended and I really enjoyed it. Still a bit hard for me to wrap my brain around but then again space stuff usually is

[8stitches 9lives · Rating 4 out of 5]

Extraterrestrial: The First Sign of Intelligent Life Beyond Earth is a provocative and fascinating book written by American theoretical physicist and Harvard University astronomer Avi Loeb. The book describes the 2017 detection of ʻOumuamua, the first known interstellar object passing through the Solar System. Loeb speculates that the object might possibly be from an alien civilization in a far distant star system, a conclusion that is considerered unlikely by the scientific community. Earlier, Loeb demonstrated that the interstellar object was not an asteroid, was moving too fast in a very unusual orbit and left no gas trail or debris in its path to be a comet. Loeb believes, due to the observed acceleration of the object near the sun, that ʻOumuamua may be a very thin disk that acts as a solar sail of some sort.Further, Loeb and colleagues demonstrated that the object was unlikely to be frozen hydrogen as proposed earlier by other researchers.

Besides ʻOumuamua, another interstellar object, the comet 2I/Borisov, has been detected passing through the Solar System. In comparison, 2I/Borisov has been found to be clearly natural, whereas ʻOumuamua has not been so determined. Accordingly, the possibility that ʻOumuamua may be alien technology has not been entirely ruled out, although such an explanation is considered very unlikely by most scientists. Nonetheless, according to Loeb, "We should be open-minded and search for evidence rather than assume that everything we see in the sky must be rocks”. His peers contend that just because something can’t be immediately explained by natural phenomena it doesn't mean it’s not natural. It is clear from the very beginning that Loeb strongly believes there is evidence of extraterrestrials out there and he postulates that many humans aren't prepared to accept that as fact. Many of his fellow astronomers aren't ready to accept that fact either.

Loeb counters that it is arrogant of humanity to assume that we are alone and that the indisputable discovery of ET life would transform our way of living. Impacting religion to philosophy and a multitude of other areas, this is a thought-provoking polemic for those interested in the meaning of life and if indeed we are alone or whether we share this vastness with alien beings far superior to ourselves. Engaging, intriguing and academic though accessible, this is a deep probe that thoroughly examines the possibilities. Highly recommended.

[Rick Wilson · Rating 5 out of 5]

This book slaps. Like, brought Avicii back from the dead to headline Coachella 2021, slaps. Like, found out your state is legalizing marijuana in the same year that the Grateful Dead and Phish are doing a weeklong concert in your town. Instilling a renewed sense of childhood wonder. The way Aloe Vera is on sunburn, this book is to the mind.

Starting with the negatives because they’re sparse. The single major drawback to this book is that it’s explaining very complex mathematical physics for laypeople. As such it’s difficult to really evaluate the credibility of the author without relying on heuristics. The guy works at Harvard. Did research at Princeton. I’m guessing he’s more than your average kook, but I’ve taken it nowhere near the number of physics or mathematics classes to understand the fine points of what is being talked about. My guess is that there are under 100 people in the world who finally could refute the mathematics of what is going on behind the scenes. So most of the math and science here goes straight over my head. I was about halfway through before I realized that the light sail he’s talking about on Oumuamua, is not the same light sail he was talking about shooting a laser at to propel away from earth in earlier chapters. I was very confused as to how the laser powered light sail could be used in a scenario where there were no lasers. Google tells me it has to do with electrons, guess they workout or something.

There are also some analogies and rhetorical bits that rubbed me the wrong way. For example, towards the end of the book the author talks about occam‘s razor and how simple is better than complicated, giving us a reminder not to overfit your model. He gently chides Aristotle for creating tortured mathematics to justify a heliocentric view of the world. Then like three pages later he goes on talking about his black hole equation and how he still needs to “fine-tune the mathematics.” I’m convinced this is a case of my ignorance making me look the fool, I just found this type of thing to be more confusing than anything. Help a mathematical toddler out. Thankfully, most of the similar quabbles I have with the writing are ultimately inconsequential to the general sweep of the book. These fall into what I consider to be more personal frustrations than global indictments of the quality of the book.

The rest of the book is a highly successful IPO of knowledge on three major points.

One, holy fahkong shit is science cool. Do you know that feeling you had as a little kid learning about dinosaurs, lasers, Norse Mythology or any sort of other thing that made you go “oh wow, awesome!” And then proceed to spend the next three months of your little life learning everything about them? This book is that for adults. I’d read a bit, then start googling whatever sweet concept this guy was talking about and end up in a Wikipedia hole deeper than the one I tried to dig as a kid when I was obsessed with big trucks and whether or not I could find China.

Two, a reminder to not gatekeep scientific research because it’s ultimately detrimental to science and society as a whole. This book has one of the better systematic criticisms of deficits in our current science research and post graduate world that I’ve seen. The author discusses how he is not your typical candidate for high-level Ivory tower funded research. But due to a series of fortunate mentors and lucky breaks he was able to contribute significantly to the small corner of the astrophysics universe that he lives in. I thought the personal bits were very well written and humble. Should be a must read for that reason alone for people considering doctorates or going into research.

Third. Dude, aliens. Heck yeah. I thought the book was fantastic in the way it was not solely focused on extraterrestrial aliens. But the author builds a pretty compelling case to point out why it’s possible that evidence associated with Oumuamua could lead us to conclude that we have been visited by some form of alien *something.

Read this book. Geek out and enjoy yourself. Astroarchaeology. That’s a thing this guy talks about. Searching for ancient alien civilizations as a field. Space-mothaflunking-archaeology. Where was this book when I was a lost undergrad trying to figure out what to work on with my life? I could have ended up whatever the equivalence to the British appropriating historical artifacts from Egypt is to the galaxy.

[Scott Kardel · Rating 1 out of 5]

As someone who teaches a college course on life in the universe I thought it important to read Avi Loeb's book Extraterrestrial in which he promotes his idea that the object known as 'Oumuamua, which passed through our solar system in 2017, was an artificial object created by an extraterrestrial intelligence.

Unfortunately Loeb ignores much of the astronomical evidence (not even bringing it to bear in this book) that suggest that this object, the first seen to ever pass through our solar system from interstellar space, was instead an interesting, but naturally occurring one.

Loeb spends a lot time working to build up his image and credibility while simultaneously attacking the scientific establishment claiming that they wouldn't even consider the evidence that this was an artificially constructed object. However there is an entire field of researchers that are eagerly seeking any signs of all that intelligent life exists elsewhere in the universe. These researchers want nothing more than to be certain that alien life exists. Loeb dismisses them too as being to rigidly held to the old belief that science won't even consider the possibility of life elsewhere.

Don't waste your time reading this, you are far better off reading any number of books that seriously tackle the issues centering on the possibilities of life in the universe.

[Z.]

EDIT 2023: Since the publication of this book Avi Loeb has gone full crackpot and thrown whatever reputability he once had out the window. I was already skeptical of his position, but now I'm fully convinced he has no idea what he's talking about and should be ignored.

Avi Loeb is a career astrophysicist, Harvard's longest-serving astronomy department chair (2011-2020), and a believer that the 'Oumuamua interstellar object which traveled through our solar system in the fall of 2017 was an extraterrestrial spacecraft. This opinion puts him at odds with the broader scientific community, most of whom agree that—while 'Oumuamua was definitely significant as the first of only two interstellar objects to be observed passing through our solar system thus far—there's no evidence to suggest it was anything but naturally-occurring.

A quick PSA: If, like me, all you want from this book is the evidence for Loeb's theory, read chapters 1, 3, 4, 5, 6, and the first few pages of 9 and skip or skim the remaining seven and a half. You're welcome.

For the rest of you: I won't summarize Loeb's arguments here, both because I hate summarizing and because they are compelling and worth seeking out in full. I'm one of those "I want to believe" types, but I'm also a respecter of the scientific method, and I thought Loeb presented his case pretty convincingly. 'Oumuamua is anomalous enough that, even if it is a natural object, it's still a pretty weird one. The shape is odd (despite the popular illustration depicting 'Oumuamua as an oblong space rock, it's apparently more likely a flat, tumbling disc), the trajectory is odd, and the variations in its traveling speed are odd. It's also way shinier than it has any reason to be. According to Loeb, the anti-E.T. camp hasn't presented any single theory which adequately accounts for all of this. I suspect he's overstating his case, but while I was immersed in the book I was just about prepared to agree with him. (Since then I've started to lean more towards the skeptic's position, but, again, I think his ideas are at least worth considering.)

The problem, of course, is that 'Oumuamua was a far-off, fast-traveling, and comparatively tiny object which scientists didn't spot till it was nearly gone. No closeup photos were taken and what data we have was gathered on the fly. Anything anyone theorizes about it is going to be rooted in conjecture by necessity, and all the more so for minority opinions like Loeb's.

More superficially, that means there's just not enough information to fill a book like this one. Generously, Loeb has five and a half chapters' worth of relevant information; the remaining hundred-plus pages of Extraterrestrial (mandated, I'm sure, by the publisher) are rounded out by Loeb's biography and credentials, descriptions of his other astronomical projects, some brainstorming about methods we might use to continue searching for alien life, several protracted diatribes against what Loeb perceives as the conservatism of the scientific establishment and the fads and cliques which pervade it, and a whole lot of philosophizing about the role of science, the importance of curiosity, and the repercussions a confirmed alien discovery might have for us on Earth.

I expected some padding, so I don't exactly hold that against Loeb. But ironically I found that all this extra stuff, meant to bolster his arguments, actually started to undermine them. Despite Loeb's academic success and prestige, he makes no secret of his disdain for the—as he sees it—closed-mindedness and skewed priorities of his colleagues. (I suspect it's no coincidence that this book came out just months after he stepped down as Harvard's astronomy chair.) He's especially resentful of the more speculative branches of theoretical physics, like multiverse theory or the study of hypothetical dimensions, which he says attract undue focus and funding despite the near-total lack of evidence supporting them. Meanwhile, he claims, the E.T. hunters like himself are ridiculed and defunded for not falling in line with current fashion. And sure, as a layman I'm inclined to agree that I'd rather my tax dollars go towards concrete space exploration projects than woo-woo-sounding speculations about alternate universes.

But whatever ribbing Loeb may get from his colleagues for playing the Agent Mulder role, it seems pretty clear that aliens are big business, in large part because of the interests of laymen like me. That's why our Mars rovers are still sifting through red dirt for signs of life and the Voyager probe is still carrying recordings of human music and speech into the depths of space. That's why this book was published for a popular audience and became an immediate bestseller. That's why, as Loeb himself tells us here, he was sought out by billionaire investor Yuri Milner to design a craft which could travel to Proxima Centauri b (a potentially-habitable exoplanet 4.2 light-years from Earth) and send back photos within Milner's lifetime. It's why Loeb is—again, by his own admission—regularly singled out by the news media for interviews and documentaries. Loeb is about as popular and highly-regarded as a working scientist can be, and as far as I can tell that's mainly because he's enthusiastic about the prospect of finding intelligent life on other planets. In light of all that, his eagerness to paint himself as a victim of scientific fashion reads more like annoyance that his unprovable pet theory hasn't been universally embraced.

Which touches on another sticky point: Loeb's proposal here is just a little too convenient. For one thing, he's clearly always had a personal and professional investment in seeking intelligent life, so it wouldn't exactly have required a stretch of his imagination to start seeing aliens in the 'Oumuamua data. His conclusions would be more convincing if they had come from a more impartial source, but, again, most of the scientific community has already rejected them as far-fetched. And that private investor-funded exploration project I mentioned Loeb is working on? Well, Loeb's idea was to build something called a lightsail which can be propelled through space by nothing more than the light of a concentrated laser beam. And what sort of alien craft, specifically, does he think 'Oumuamua must be? A lightsail, of course! He's aware of how this looks and tries to refute the truism that "when you're holding a hammer, everything looks like a nail," and in fairness to him it does make a certain amount of sense that someone who's worked on these kinds of projects might also recognize signs that other researchers wouldn't. But it's concerning to say the least.

(Speaking of: I hesitate to mention this since it's not directly relevant to the science itself, but given how much of himself Loeb puts into this book it's unfortunate that I found many of his non-scientific traits and opinions disagreeable. Aside from his general martyr complex—get ready for a lot of self-comparisons to Galileo—he's a vocal proponent for the building of Hawaii's Thirty Meter Telescope on sacred indigenous land, his outlook on his mandatory IDF service and Israel's ongoing military activity is pretty rosy, and just recently he got in trouble for mansplaining the SETI program to one of SETI's founders. I'll leave you to make of all that what you will.)

So, as much as I'd like to be swept up in Loeb's enthusiasm, I just can't do it on the basis of a few slim chapters. I need a more unbiased representation of the consensus opinion before I'm truly willing to take a "side," and it bothers me a little that Loeb's fringe theory-slash-diatribe against the scientific establishment is going to be the first and perhaps only one many laypeople read on the subject. (Lord knows what we all need right now is more distrust of scientists.) I love learning about the search for extraterrestrial life—that's why I picked this up to begin with—and I sincerely hope we find real evidence someday; but the biggest takeaway whenever I read or watch something about space exploration is that scientists are doing and learning so many cool things already, most of which never get publicized precisely because they're not as attention-grabbing as Loeb's alien probe. 'Oumuamua was a fascinating discovery regardless of what it "really" is, and you'd hope that someone with Loeb's unique position would be the first to celebrate that.

[Wanda Pedersen · Rating 3 out of 5]

”If you do not expect the unexpected, you will not find it.”—Heraclitus of Ephesus

I heard Loeb interviewed about this book and immediately put a hold on it at my library. As soon as it came in, I grabbed it and wasted no time getting reading. For me, Loeb's interview was more inspiring than his book. But I do think he has valid points and that the nature of the interstellar object known as ‘Oumuamua should be investigated thoroughly.

In essence, the astrophysical community seems to be sticking to the old wisdom If you hear hoof beats, think horses, not zebras. In many endeavours this is sensible advice--I've had to deal with a number of beginner birders who are adamant that they've seen something highly unlikely, say an Asian accidental in Western Canada or a species that exists in North America, but not in our area. The vast majority of the time, they haven't seen the unusual, just a normal bird under odd circumstances. But there are always those times…. I know of a Curve Billed Thrasher seen in Northern Alberta one winter, for example. So Loeb is right to remind us that the hoof beats might be horses, donkeys, or zebras and we would do well to allow for the unusual.

It's unfortunate but unsurprising that Loeb's style is somewhat pedantic. I imagine that he's used to being one of the smartest guys in the room. This book may be mostly about ‘Oumuamua, but it also is a comment on the state of the academic world, where reputation and funding opportunities seem to outweigh intellectual curiosity. He points out the unjustified denigration of those who search for life in the universe (such as the SETI project). He doesn't say so, but I think the crop-circles-and-alien-abductions crowd has tarnished this branch of study. Certainly if there were aliens actually visiting Earth, there would be no need to announce themselves so obliquely.

Although he strongly suspects an extraterrestrial origin of ‘Oumuamua, I think what he most hopes for is the opening of the scientific mindset to include this possibility. Preparing for the next appearance of such an anomalous object and getting more definitive answers should be the next goal.

Cross posted at my blog:

https://wanda-thenextfifty.blogspot.c...

[Tom · Rating 2 out of 5]

The central idea presented in this book is well thought out and carefully presented. The evidence that the author presents for the intelligent design of ʻOumuamua is compelling, and provokes a lot of interesting thoughts. And the author adds interesting information about the possibility of intelligent life beyond our galaxy that was also generative. And he's highly qualified and a good scientist.

But that comprises about 20% of the book, and is really all that was needed. The rest is mostly filler--nice family stories, lots of scientific speculations, a bit of moralizing, much repetitive complaining about the scientific establishment, and then pretty much a list with summaries of all the relevant papers he and his grad students have written on anything remotely related to this topic. I realized not quite half-way through: Wait, he's got nothing more of substance to say on this topic! Which was frustrating because I'd spent good money on what could have essentially been a magazine article.

[Peter Tillman · Rating 3 out of 5]

An interesting short book, ostensibly about 'Oumuamua, the first documented interstellar object visiting our solar system. More interestingly, it’s about the process of doing science. It’s a short book. Loeb’s case for 'Oumuamua being an abandoned alien spacecraft is pretty weak, I thought. Since he wrote the book, the consensus now is that it was a piece of (mostly) nitrogen ice from an exo-Pluto, https://arstechnica.com/science/2021/... The ASU guys arguments seems reasonable to me. Loeb and a student made a theoretical counter-argument that there’s not enough nitrogen available, https://arxiv.org/abs/2103.14032 . But that’s silly, since we’ve seen massive amounts of nitrogen ice outcropping on the surface of our Pluto. Observation trumps theory, every time!

So. You can disregard Loeb’s weak argument for 'Oumuamua being a piece of an ET spacecraft. He still makes some good points on keeping an open mind, not following the crowd, strive for simplicity in your work — and he’s led an interesting life. Here’s the best review I saw online: https://www.nytimes.com/2021/01/26/bo...

If you read the book, I recommend lightly skimming the 'Oumuamua stuff after its first appearance. The balance of the book will be worth the 2-3 hours that will take, I think, depending on your tolerance for a pretty meandering story. 2.5 stars, rounded up. Recommended with reservations. You may want to look at some of the better 2-star reviews here first, such as Yun's, https://www.goodreads.com/review/show...

The book to read about sticking to actual evidence in science, vs. pretty, fashionable theories, is Sabine Hossenfelder’s wonderful “Lost in Math: How Beauty Leads Physics Astray.” A much better book: 5 stars! My take: https://www.goodreads.com/review/show...

[Nore · Rating 1 out of 5]

While the concept is extremely interesting - our first interstellar visitor, and to think, it may have been alien in nature! - this book is less than 50 pages of genuine discussion of 'Omuamua and over 150 pages of random biographical stories that bored me to tears and had no relation to 'Omuamua at all; endless, repetitive whining about The Man dragging scientific progress down; complaining about how everyone cares more about getting likes on social media instead of seeking true knowledge; and history lessons about science that, while interesting, were only dragged out to underscore the bone he has to pick with conservative science.

Honestly, I ended up skimming the last 50 pages. Whatever credibility he had at the start of the book had faded away by the time he repeated his story about herding chicks fresh out of the incubator, like that has any relation to the hard science behind the origins of 'Omuamua. I have a lot to read, including another recent book about space, and I'm not going to waste my time on yet another story about his life on the farm as a kiddo. Sorry, Dr. Loeb, I generally don't read biographies!

[Beauregard Bottomley · Rating 3 out of 5]

Pascal’s wager only convinces fools or the already superstitious. The author’s conviction which he turns into a wager is that a rock hurling through space making an inexplicable deviation as it zoomed past the sun is most simply explained by an advanced civilization’s thrown away garbage technology equipped with a solar sail. The author thinks that by itself merits a Pascal like wager such that we assume that the rock must have come from an advanced civilization and we should drop everything else and assume that fact free assertion as real and act as if humanity depends on that belief. (When you multiple even the smallest probability by infinity, you get an infinite effect).

The author kept on calling a doubter in his fact free assertions about proof for advanced alien civilizations arrogant, or full of hubris, or not rational and not using reason. Just because one might think that there is no evidence for asserting that the universe is teeming with advanced civilizations doesn’t make one arrogant. I think it makes one a follower of the evidence. I think Fermi’s paradox is reasonable, I think the great filters are real and the author skimmed over them because it didn’t fit his story. For example, he doesn’t mention symbiogensis.

I want to appeal to the first Mrs. Carl Sagan, Lynn Margulis. She was mocked, ignored, argued against and then finally fully accepted as if what she was saying was obvious all along with her symbiogenesis theory, that is when a prokaryotic got swallowed by another prokaryotic and gave us eukaryotic thus leading to a complex life form on earth. A ‘great filter’ event here on earth which perhaps might have only happened once in the galaxy leading to the production of the currency for complex life through producing ATP. The point is becoming complex is not an easy thing to do and as far as we know has only happened once in the 3.8 billion years life has existed on earth. All complex life links back to that mitochondria event (plants do something slightly different with photo-synthesis). It is not arrogant to think that can be an incredibly rare event and maybe has not happened elsewhere in the observable universe or at least in our own galaxy.

I pick Lynn Margulis great filter event for another reason. The author thinks that the simple explanation is better than the correct explanation or the best explanation. Margulis also thought the simple explanation for the World Trade Center 9/11 attack was most easily explained as an inside job which of course is nutty. She also thought the earth was alive and Gaia best explained earth’s balance which of course is foolish. She was right about one very big thing, and foolish about other things. Simple as the author advocates is not the only guide that we should abide by.

Conspiracy theories are best ignored, they always have non-refutable hypothesizes. Qanon is not worth refuting. They will tell you that they are simple and therefore the correct explanation. Only a fool will engage with responding because it is a non-refutable hypothesis and is therefore a pseudo-science. Chandra Wickramasinghe advocates panspermia (life on earth came from outer space), this author dwells on panspermia as part of his belief system but doesn’t mention Wickramsinghe. Nobody should waste their time refuting that hypothesis, as nobody should waste their time refuting Qanon, or unsubstantiated hypothesizes which state that solar sails exist on rocks as part of space junk from advanced civilizations because a slight deviation in acceleration needs to be explained. Actually, I didn’t understand exactly how the imaginary solar sails would have solved the deviation problem better than other phenomena, but I suspect strongly that other mechanisms could explain the deviation in acceleration problem just as well. I mention Wickramsinghe because a book I once read said that Wickramsinghe thought it was up to others to prove him wrong, and the author said that he just didn’t want to waste his time on assertions without foundations. I feel the same way with this author’s assertion. I can’t say panspermia is not real, and I can’t say that rocks with solar sails from other star systems aren’t real, but I don’t think I’ll dwell on it or definitely I would not waste my career on either assertion.

It is not arrogant to believe there are not advanced civilizations within our galaxy. The simple explanation is not always the correct explanation. Instead of saying ‘God did it’ as a Christian apologist does, this author is just saying advanced aliens did it. Just because we cannot fill in the blanks doesn’t mean we should put God in the gaps, or in this case, advanced aliens in the gaps. By all means, I hope we continue SETI research, but I reject the framing of a rock hurling in space must be from an alien civilization as Pascal’s wager and assuming that not accepting wild theories about alien civilizations is an existential threat to future humanity or makes me arrogant because I have doubts.

Comments to this review won't let me add the links so I'm putting this addendum added to the review (11/29/2023),
I regret the three star rating to this book. I realize now this author is a bigger idiot than I could have imagined. I wish I had given it one star.

Couple of months ago the NYT gave Loeb a story on his crazy quest for a 'alien meteorite' on the bottom of the ocean. https://www.nytimes.com/2023/07/24/sc...

This youtuber who I follow puts Ari Loeb in his place with this takedown, https://www.youtube.com/watch?v=RD8Ei...

I fear that the NYT and Harvard are going to destroy us by their constant pseudo-science nonsense that they legitimatize. What next will we have a Cardinal saying that vaccines have microchips that track us, or that Uri Geller was right? Nevermind, that's already happen.

I'm embarrassed I gave the charity of understanding to this nut job of an author and gave this piece of crap book 3 stars. My bad. Pseudoscience is the friend of anti-democratic forces and we can't rely on NYT, Harvard or others to save us from vaccine denying, election denying or aliens are on the bottom of the ocean fantasy enablers.

[Lyn❤Loves❤Listening to Real Voices Only!!!!❤️🎧📚 Addict ON HIATUS · Rating 4 out of 5]

Audio 5 Stars
Story/Content 4 Stars

[María · Rating 3 out of 5]

Me parece muy interesante, arriesgada y valiente la hipótesis sobre Oumuamua que nos expone Avi Loeb en este libro, pero a pesar de lo corto que es lo he encontrado bastante repetitivo.

[David Rubenstein · Rating 5 out of 5]

Avi Loeb is a theoretical physicist; he has a PhD in plasma physics, for 12 years he was the chair of Harvard's astronomy department, he is the founding director of Harvard's "Black Hole Initiative", he is the director of the Institute for Theory and Computation in the Harvard-Smithsonian Center for Astrophysics, and he is the chair of the Board on Physics and Astronomy of the National Academies. He is the author of 700 scientific papers and 4 books. The list goes on and on ...

So, Professor Loeb is no slouch. He is not a crackpot. And he has publicized his hypothesis that in 2017, our solar system was visited by a non-artificial probe from a distant civilization. The object is named "Oumuamua", which means "scout" in Hawaiian, as it was first discovered using a telescope in Hawaii.

A portion of this book is devoted to the data and Loeb's interpretation, of a fast-moving object that visited our solar system, and was observed for a total of 11 days before it escaped into deep space. There are no contraversies about the facts;
1) The object is on an unusual hyperbolic orbit that could not be captured by the sun's gravitational pull. It is the first object to be observed with a truly interstellar trajectory.
2) Unlike a comet (sometimes called a dirty snowball), it has no tail.
3) Variability in its reflectvity indicates that it has an extreme shape; either an elongated cigar-like shape, or a very thin disk
4) High luminosity
5) While leaving the solar system, the object accelerated!


Any one of these aspects is unlikely, but statistically possible. It is the combination of the likelihoods that cannot be easily explained with known physics. Moreover, if the object is natural, then its visit to our solar system, at the speed that was observed, is very unlikely. The density of such objects would have to be very high in interstellar space.

Professor Loeb suggests that the object is a thin, 100-meter wide light sail. We on Earth could put such a craft into space at high speed, using today's technology. He knows, as he has explored the potential of light sails. The first light sail would be costly, but the economies of scale would allow the second, third, and hundredth to incur little additional expense.

We will never have another chance to observe this object again. However, Professor Loeb suggests that preparations could be made before the next such object arrive, to launch a rocket in short order to take photographs to get definitive proof one way or another.

The majority of the scientific community believes this was simply an asteroid or unusual comet. But the arguments presented here give a pretty good case that it could be an alien probe.

[George Ilsley · Rating 2 out of 5]

I read many memoirs, but don't appreciate "bait and switch" memoirs. This book claims for itself: "Harvard's top astronomer lays out his controversial theory that our solar system was recently visited by advanced alien technology from a distant star."

Yes, okay. This book does discuss 'Oumuamua, as that mysterious object became known. What can be said about that interstellar object can be summarized in three words: "We're not sure." The rest is theory.

The theory and discussion around 'Oumuamua would make a fascinating article about 10 pages long (maybe 30 pages for the real scientists). Those fascinating 10 to 30 pages are not even sequential in this book, so one must wade through piles of extraneous material (goats, chickens, everybody he has ever met, Plastic Beach in Hawaii, his CV, resume and bibliography) in an attempt to locate what is declared on the cover.

The result, I'm afraid, was skimming, frustration, boredom and exasperation.

[Mansoor · Rating 2 out of 5]

Deeply unconvincing. I liked this bit though: "Despite the absence of experimental evidence, the mathematical ideas of supersymmetry, extra-spatial dimensions, string theory, Hawking radiation, and the multiverse are considered irrefutable and self-evident by the mainstream of theoretical physics. But go beyond the groupthink and look more closely at these ideas. For instance, supersymmetry. This theory, which postulates that all particles have partners, is not as natural as prominent theorists predicted it would be. The latest data from the Large Hadron Collider at CERN did not find any of the evidence expected at the energy scales it probed to support supersymmetry."

[Repix Pix · Rating 2 out of 5]

Le sobra el 90%, no te digo más. Mucho marketing y poco lerele.

[Jessaka]

Well, this book didn’t have a lot to say, and at the same time, it did. The most powerful telescope is in Maui, and several years ago it tracked a spacecraft from the moment it entered our solar system to the time it left. It went by Mars and Earth and was ¼ mile long. Its speed was astronomincal, and it was shaped like a cigar. It was not an asteroid or a comet, etc. And this is all I can tell you about the book.

[Márcio · Rating 4 out of 5]

3,5/5

UFO? "E.T. phone home?" You are wrong if you thought this book is about close encounters of the third kind and it doesn't even come close to mention Roswell. I confess the title might be deceiving, but one has to consider that whenever we think of Extraterrestrial life, we tend to have Hollywoodian visions.

Avi Loeb is an Israeli-American theoretical physicist at Harvard University and "Extraterrestrial" is partly about 'Oumuamua, considered the first known interstellar object detected that has visited our Solar System. Others may have already passed through, but this was the first time we were able to record data using astronomic instruments. Many attempted to classify the object as an interstellar meteor or comet, while Loeb and his postdoc student Shmuel Bialy directed their researches, considering part of the data available, that it could be an extraterrestrial object, though other scientists stated that the evidence is not enough to consider such a premise. And here are the main focus of the book.

Loeb's first goal is to introduce the theme of extraterrestrial life elsewhere using biosignature and tecnosignature in order to try to find out if we are actually a miracle and the only planet with living species all over the whole (observable) universe or if there are chances that other planets might harbor life, from the simplest kinds to advanced ones. For there might have already existed civilizations far from the point of advance we are today, that might have perished already if one considers that the universe is almost 14 billion years old. Thus, 'Oumuamua can even be reminiscent of such a long perished civilization. But we also might consider that life might exist in plenty all over the universe, and he presents a lot of arguments why we haven't still had the chance to find them out like SETI has tried to for so long.

Loeb's second goal is to call attention to what the elites in the science field and in academia, also known as Vanity Fair, do in general. They hold power enough to smash researches and researchers. Examples abound. It is a criticism that is well known not only in the astronomy field but in all fields of knowledge.

Loeb keeps the reader interested all along with the book, but at a certain point, he can become pretty repetitive in his goal to convince the reader concerning his thesis.

[Sebastian · Rating 3 out of 5]

This is an OK popular science book by Harvard astronomer Avi Loeb discussing a theory that 'Oumuamua, which visited our solar system in 2017, may have been an alien artifact. It suffers from the classic problem of popular science books: short description of the actual content on the cover, then a lot of personal background and autobiography. Note to editors: literally no-one cares about Loeb, David Sinclair, whoever and what they had for breakfast last Tuesday. Cut it out and stay on topic.

'Oumuamua is a peculiar interstellar object that visited our solar system in September and October of 2017 [3-5]. It appeared peculiar first because of it's oblong or possibly pancake-like shape, about 1:5-10 length to width against a maximum observed ratio of about 1:3 across all asteroids we've every measured. Next it appeared peculiar because it was influenced by a force other than gravity as it swung around the sun. Sometimes solar energy will sublimate some ice ("outgassing") which creates a force on comets -- but in this case no such activity was observed [37]. What caused the deviation in trajectory then?

Loeb talks about his work developing "solar sails" and notes that if 'Oumuamua were one hundred times more rareified than air, another explanation for the deviation could be harnessing the energy like the sails he's designed to generate force [44]. Could it have been an alien buoy? Some kind of scout? Alien debris? We don't know the answer to these questions but we know that 'Oumuamua was a very weird, very rare object that we can't explain.

The argument here is mainly deductive and I think suffers from a major weakness in the 100-times lighter than air point. I have no idea what could maintain structural integrity with 100x less dense mass than air. There just aren't enough atoms in there to interact I would think. I'm open to hearing good arguments but this seemed like a HUGE leap that just gets mentioned and scuttled.

The rest of the book is Loeb talking about himself and the culture of academic science which is very inhospitable to wild new ideas. I agree strongly with Loeb but at 100+ pages of repetition of roughly the same points, I would have wanted more of the science I was promised.

[Brahm · Rating 2 out of 5]

2 stars = "it was ok".

The good: A super interesting hypothesis about an unusual and (according to Loeb) potentially extraterrestrial interstellar object called 'Oumuamua that flew through our solar system in 2017 (or more interesting: was the object at rest relative to the milky way, and our solar system passed a "stationary" buoy?). An interesting thought experiment about what the most rational conclusions are to fit unusual data: call it a "normal" space rock that's so unusual it'd be one-in-a-bazillion, or invoke Occam's Razor and call it an alien lightsail?

"And yet it deviated" - a fun argument to keep coming back to, as the object accelerated when it whipped around our sun, and the total acceleration could not be accounted for by the gravity of the sun alone. So what gave it that extra kick? (a lightsail)

Lastly, good bit about controversies in science. Loeb makes the case that unusual hypotheses like this drive more innovation and discovery if assumed to be true (until proven otherwise), vs. maintaining the status quo if assumed to be false.

The not-so-good: Out of 12 or 13 chapters, only 3 or 4 were actually about 'Oumuamua and its properties. In reality there are only about 12 days of data on 'Oumuamua and there's not a lot there. No conclusive evidence, hence the debate is not settled. Loeb fills the rest of the chapters with a mix of scientific whimsy, storytelling about his youth and family history, career history including military service in Israel, philosophy of science ("the public has a right to know about disagreements," etc.), plenty of history on Loeb and his postdocs' supporting work in the area, and a left turn into the theory of black holes near the end that felt very out of place.

There is a subtle issue with tone, credit and attribution in this book. Loeb talks about his "original ideas" and hypotheses in research, the work "his" postdocs do, etc. For all his discussions on lightsails I was waiting for him to mention that humans have demonstrated lightsail technology, very recently with the Planetary Society's Lightsail 2 spacecraft - but it seems like any recent research or development that's not Loeb goes unmentioned (there is more content about historical figures: Copernicus, Galileo). What I'm getting at: I like it when brilliant people like Loeb show a bit more humility and share credit more widely.

Conclusion: Fascinating and exciting hypothesis, but the book can be bypassed to learn about 'Oumuamua: everyone should read this media-friendly paper (PDF) on Loeb's website, and optionally, reading the abstract, intro and conclusions on the full scientific paper (also PDF). There is also a ton of media one can Google but I think the sources above are a less diluted starting point.

[Rob · Rating 4 out of 5]

Intriguing take on a mysterious object that appeared to use some form of solar sail technology -- at least according to the author Avi Loeb. He brings a compelling case based of scientific data. At least, it's one reasonable theory. It's unfortunate we only detected this object as it was already heading outside of our solar system. More data would strengthen Avi's case. This book is most interesting when Avi talks about future propulsion technologies that may be closer in our reach than many would believe. Thumbs up!

[Leili V. · Rating 1 out of 5]

This is not a book about a really cool space anomaly, but rather an autobiography on how amazing the author and his family is. He brags a lot about his past achievements and lauds his family, taking care to show off his kids as much as possible. Yes, science should be made more accessible and in a manner that is exciting for the general public, but no, I did not choose this book because I wanted to share my own personal sour grapes about how society desperately needs science literacy, nor did I choose it to learn how to make science more interesting for my own smol human that I’m homeschooling. He makes a big deal about not being religious, but about 35% of the book extols Zionist ways. Again, we should never forget history, and what happened in Germany in the past is important and tragic, however, I did not want to read this book because I needed to learn about eugenics or British colonialism in the Levant. The author whines and gets defensive often. He claims arrogance isn’t a good trait to have, but does not see it reflected in his own words when he berates other scientists and students. It’s clear he’s lead a very privileged life and has his own biases he could be considering. He also seems to think that any current lack of innovation can be blamed on social media... Some of his ideas are quite bizarre—not that the space anomaly in question could have come from an alien civilization, but that most scientists are giant man-babies and students must be hand-held through basic scientific concepts... Lastly, he leaves out the biggest hurdle to human space travel in all of his examples: the vast distance!! Light sails are cool my guy but we can’t take a ride on them (yet). It just seemed like a really huge thing to leave out... Next time, please stick to the topic and use logic to back up your claims.

[David · Rating 2 out of 5]

The concept is fascinating, but as brilliant as he is, Loeb just isn’t a writer. He tried, but this ended up reading like a textbook. Well, a textbook with some random talk of goats. I learned what I was interested in through a couple web pages. The book just drags it all out. I admit, I’m not a science guy, and I took a chance here. I was just bored out of my mind.

[Raquel · Rating 1 out of 5]

Muito controverso. Não é muito comum este género de literatura por parte de físicos que têm currículos académicos sólidos e são muito considerados pelos seus pares. Este livro não dividiu muito a comunidade científica: a maioria dos físicos/astrónomos considerou que este era um livro para as massas. A abordagem de Loeb não tem a maturidade, humildade e aquele grau de cepticismo que convém à ciência.
Nesta obra encontramos afirmações, teorias encerradas e um misto de "2001: a space odyssey" e "Contacto", com pretensas conclusões científicas à mistura.

Mas vamos por partes: em 2017, um objecto muito peculiar entrou no nosso sistema solar. Foi baptizado de "oumuamua". Descobrir a sua origem tornou-se um desafio. Avançaram-se muitas sugestões. O debate tornou-se emotivo. Acabou por ser posta em cima da mesa a mais emocionante das sugestões: " oumuamua" era efetivamente "o mensageiro" de civilizações alienígenas. As suposições em ciência são importantes: combatem o dogmatismo, desafiando o "status quo". Mas quando a discussão se torna arrogante e cheia de certezas, o debate científico sai empobrecido.

É legítimo que Loeb se questione e traga à discussão novas ideias acerca dos mistérios que mais nos assombram, mas não é isso que transmitiu nesta obra.
Não é pela eterna discussão acerca da possibilidade de vida " extraterrestre" até porque a célebre frase "a ausência da evidência não significa evidência da ausência" é bastante esclarecedora nestas matérias.

Não gostei deste livro; o corpo celeste (ainda sob debate) "oumuamua" já deixou a nossa vizinhança celeste, mas poderia ter levado este livro para se divertir na sua longa viagem de regresso ao infinito.

[David Agranoff · Rating 5 out of 5]

Before the review let me drop the links for my interview with the author Dr. Loeb!

https://podcasts.apple.com/gb/podcast...

https://open.spotify.com/episode/5TBq...

https://youtu.be/hol7AhqEf4U

Why study the universe without a sense of wonder and humility at all? Why are those two things so important? Scientists and researchers that peer out into the cosmic vastness of space can’t do it without wonder. For me, I can’t look at the night sky without those two things. I know we might as well be a frog in well there is so little we can see in our tiny little window to the universe. How can you not wonder or feel humbled?

One of my passions besides Horror and Science Fiction is space and astronomy. I listen weekly to several astronomy podcasts and constantly searching for videos on various topics related to that passion. Over the last few years, one of the voices that cut through for me was Avi Loeb.

I know it seems silly to say about an astronomer but bravery comes to mind when I think of his sense of wonder. He is not afraid to speculate or think wild or outside the box ideas. He is still a scientist so through a slew of papers over the years he has backed up those ideas.

A few years ago he stepped out into the media spotlight with one of those ideas. This was after Oumuamua the interstellar object was discovered racing through our solar system. Loeb pointed out that it was most likely a piece of technology. So, you see that is a huge deal because that would be proof that intelligent extraterrestrial life was indeed out there. They may have lived and died millions of years ago, and this object may have traveled long after it was gone or maybe it is a scout it is hard to say but one of the points of this book is we should try and find out.

I know people were hoping that a flying saucer would land on the lawn of the White House but the truth is much more likely to be something less splashy. Look I am not the astronomer, I don’t have to choose my words as carefully when you look at what Oumuamua did it is pretty fucking rad. This object came on a path from above turned at an incredible speed through changed directions when the orbit of Mars and out past Saturn in a totally different direction.

“instructive to view things from ‘Oumuamua’s vantage point. From that object’s perspective, it was at rest and our solar system slammed into it. Or, in a way that works both metaphorically and, maybe, literally, perhaps ‘Oumuamua was like a buoy resting in the expanse of the universe, and our solar system was like a ship that ran into it at high speed.”

Almost no one besides Loeb in the academic community has even considered the idea of thinking like Oumuamua. It is a simple thing but it shows a willingness to think about this object in new ways. What kind of arrogance does it take to see something like this and assume that we know what it is already.

What Loeb points out several ways in this book is that scientists afraid to admit the unconventional conclusion are bending over backward to try and explain how this happened naturally. The cool thing about this book is it tells Loeb’s story in parallel with the story and science of Oumuamua. Going from the small farm he grew up on to doing astronomy at Harvard we get to understand the person at the center of this story. We can see why Loeb would be the one raising the flag for this discovery.

It is that, a discovery. No one debates that but the debate is this. Did the discovery of Oumuamua show us the answer to one of the questions humanity has struggled with since we have had written language?

Loeb makes a really great case yes Oumuamua is one of the greatest discoveries in human history, the funny part is most don’t see it that way. We only had a few months as a species to observe Oumuamua, but that doesn’t mean we might not get another chance, and more importantly, if we open our minds and bet on Oumuamua being alien technology we can look with fresh eyes at the data we have.

More importantly towards the end of the book, Loeb explains how and why this species hell-bent on self-destruction through nuclear weapons and human-directed climate change need to make this bet now.

“A more ambitious bet would be to learn from what we imagine a more mature civilization might have attempted. To take the small scientific leap and allow the possibility ‘Oumuamua was extraterrestrial technology is to give humanity the small nudge toward thinking like a civilization that could have left a lightsail buoy for our solar system to run into. It is to nudge us not just to imagine alien spacecraft but to contemplate the construction of our own such craft.”

Oumuamua can and should be the call to this species to think like earthlings and mature. Yeah, I loved this book and I am happy to say I will have Professor Loeb on my podcast soon. Pre-order this book and look out for the interview.