“Alone in The Universe”: John Gribbin’s Argument for Why Most Star Systems in the Milky Way are Uninhabitable

By Cory Davis

This is a breakdown of John Gribbin’s argument as made in his book Alone in the Universe: Why Our Planet is Unique (2011) for why most star systems in the Milky Way Galaxy are uninhabitable for technological life.

Alone in the Universe -- Why Our Planet Is Unique.jpg
Alone in the UniverseWhy Our Planet is Unique (2011) by John Gribbin

On December 19, 2020, I wrote a review of this book, giving it 4/5 stars. I thought it was a fun thought experiment which made me wonder and ponder our existence in the universe. If you are interested in checking it out, please find it here. There were four reasons that I did not give it a 5/5: (1) there was no summary of the argument, (2) there was no clear outline about why it is important, (3) the conclusion was extreme, and (4) the title of the book is not honest.

On December 30, 2020, I summarized the author’s argument consicely into 12 premises and a conclusion for why we are alone in the Milky Way Galaxy as a technological civilization. If you are interested to check it out, please find it here. His argument first reduces the the amount of stars that could harbor life from 100% of the Milky Way to just 10%, based on metallicity and location. On January 1, 2021, I broke down this argument for why most of the Milky Way area is uninhabitable for technological civilizations here. But this still accommodates 10% of the stars in the Milky Way. That leaves between 10 – 40 billion stars to consider as potential systems to harbour life. However, the author shreds this down from 10% to 0.06% in his discussion about habitable star systems and types, the topic of this post.

In this post, I will break down John Gribbin’s argument for why most star systems in the Milky Way are uninhabitable for technological civilizations. His argument is as follows:

Most stars are not the right type to accommodate complex life like ours.

Star Types (Not to Scale)

75% of the stars in our neighbourhood are red-dwarf stars with about 10% the mass of our sun.

  • Their habitable zones are very narrow and extremely close to their star, much closer than mercury is to the sun. They are around 5 million kilometres to their star, whereas mercury never gets closer than 46 million km to the sun. Because of this, these planets would be tidally locked, where one side of the planet always faces the sun, and the other side faces away. This means that one side the atmosphere would freeze off, and the other side would get scorched. You are also much closer to the star and therefore more vulnerable to solar radiation.
  • A note that the author does not make here is that some argue that tidally locked planets would have a zone of habitability between the frozen and scorched sides where temperatures would be just right. The oceans may not completely freeze or burn off because of circulation. This may be true, and create a habitable area under water. However, air moves in response to differences in pressure (related to temperature). Hot air rises and cold air (more dense) moves in. If you have an extremely cold side, and an extremely hot side, such as with a tidally locked planet, this would create winds more violent than we can imagine on earth. The chance of a “green belt” (as they call it) forming on land plummets. There may be a possibility of some lichen-like life on land here, but I am skeptical of complex life thriving on land. Please correct me if I am off-base.
  • Red Dwarves are also much more active than the sun. They blast their solar systems with radiation that would strip away atmospheres and blast life with dangerous radiation. You are also more vulnerable to things like solar flares and coronal mass ejections.

Large stars also have more difficult habitable zones. They have much shorter lives and are way hotter. Therefore, intelligent life most likely couldn’t evolve there either. The range of habitable stars would be only K-type, F-type and G-type.

Most stars inhabit multiple star systems.

Artist’s impression of the double-star system GG Tauri

Most stars orbit at least one other star which threatens stable planetary orbits, circular planetary orbits, stable habitable zones, and stable climates. Therefore, most multiple star systems cannot accommodate the evolution of technological life.

Only 20% of stars are single. Even in single-star systems, there is a lot that could go wrong for complex life. However, binary, or triple star systems are more dangerous for the planets who reside there. Very stable orbits can only occur in a narrow range of conditions in them. But even where they do occur, it is unlikely that they are circular, causing the planet to dip in and out of the habitable zone.

Fluctuating heat caused by the binary system would also cause problems (different temperatures of each star). Just a 4.5-degree (Celsius) shift on earth today could threaten civilization. The habitable zone would also vary greatly. The two stars would be getting hotter at different rates as they mature, which would impact the stability of planetary climates.

Most stars do not show refractory element patterns conducive for rocky planet formation

The Sun, with Bird Silhouette

Stars that have depleted refractory elements at their surface tend to have rocky planets, stars who have not tend to have gaseous giants in their early solar system. Only 10% of stars exhibit refractory element patterns.

  • When the sun was about 2 million years old it received a blast of iron-60 and aluminium-26 from a supernova very close to us at the time.
  • Our sun had an unusually high metallicity – which is a puzzle easily solved by the above statement.
  • However today, sun has less heavier elements at its surface than the interior – vaporizing refractory elements like calcium and aluminium at high temperatures – these elements are common in rocky planets like the earth. So, the sun has been depleted of refractory elements which in turn have been used to form rocky planets.
  • The behaviour of our sun and the formation of rocky planets is related. That depleting these “refractory” elements at its surface is related to the formation of rocky planets. Early on these elements that would have been present in the sun’s atmosphere went into the formation of rocky planets.
  • Depletion of refractories seems to be a signature that there are rocky planets like ours.
  • Stars that don’t exhibit this behaviour tend to have gaseous planets in the inner solar system to the detriment of any possible rocky planets that formed there.
  • Refractory elements are not volatile and include things like silicate that make up rocks – and form asteroids, rocky planets, and moons. Other elements are volatile and form gaseous planets.
  • Only about 10% of stars exhibit refractory element patterns that fit into this category


In a previous post, I broke down John Gribbin’s argument for why most of the Milky Way Galaxy is uninhabitable. He argued that 90% of stars in the Milky Way are not habitable for technological life due to their location with respect to metallicity content. That leaves only 10% of stars to consider for the discussion today.

  • 75% of these stars are red dwarves, or M-Stars. This lowers the percentage of stars to consider from 10% to 2.5%.
  • Only K-Type, F-Type, and G-Type stars should be considered to accommodate technological life. This reduces the number of stars from 2.5% to 2%
  • Multiple star systems are dangerous. Only 30% of the 2% are left – 0.6%. He notes that only 20% of stars are single. So here he includes some multiple star systems as candidates by incorporating 30% for consideration.
  • Only 10% of stars exhibit patterns of depleting refractory elements at their surface to be used for rocky planet formation. That leaves only 0.06% of stars left.

Even if it we were to ignore all other premises (here), you could still argue that 0.06% is rare. That is 0.06% of 400 billion. That leaves roughly 240 million stars out there, in the galactic habitable zone, with the right kind of star, in the right kind of star system, and exhibits behaviour that depletes refractory elements at their surface to form rocky planets. Many of these stars may be younger or older than our sun, in various stages of their life cycles.

So, it is worth noting that stars live in and die, leaving a relatively narrow period of time that they can accommodate technological life:

  • It took almost 4 billion years to produce complex life on earth
  • The sun is heating up giving us a limited amount of time before the oceans are evaporated
  • Time is important, and the stage in the star’s life cycle is indicative of the probability that complex life exists within its solar system

These are just a few premises for why John Gribbin argues that we are alone in the Milky Way Galaxy. Other interesting points to drive that 0.06% down even further (he argues) are: (1) that evolution is not goal-oriented, but rather adapts to environmental changes, (2) our solar system is uniquely accommodating, (3) our planet is uniquely accommodating, (4) the explosion of complex life was a rare event that does not guarantee lineages who could result in technological civilizations, (5) mass extinctions play a critical role in evolution, (6) there are several looming existential threats to humanity, and (7) human level intelligence is rare, even in the context of complex life.

If you are interested in having those arguments broken down further, as argued in the book, please let me know in the comment section below.


I think the author makes a compelling argument, that provokes imagination and big thinking across vast expanses of time and space. However, I am not necessarily convinced by the argument, as the conclusion at the end of the book is extreme. If we take his argument at face value, I think that one conclusion we could make is that technological life in our Milky Way Galaxy is rare, and the the likelihood of two existing at the same point in time and close enough in space to recognize each other is vanishingly small. With that said, not all arguments were totally convincing, and there are still many unknowns.

As always, I found this topic very interesting. But I am more interested to hear what your thoughts and opinions are. If you have any thoughts, comments, feedback or ideas, please share them in the comment section below. I am sure they will create an interesting dialogue. If you enjoyed this post, please give it a like and subscribe, or follow me on twitter @interestpeaks. I always appreciate it when you do.

Thank you so much for reading this post. I look forward to my next book review on “This Is Marketing” by Seth Godin. If this book interests you, stay tuned for future posts.

Book Breakdown Part 2: Lindo Bacon’s Health at Every Size

By Cory Davis

On January 30, 2021, I wrote Book Breakdown Part 1: Lindo Bacon’s Health at Every Size (here). On January 23, 2021, I wrote a book review for Health at Every Size (2010) by Lindo Bacon (here). I gave this book a 3/5 for three main reasons: (1) the argumentation and logic was not convincing, (2) some of the messages were dangerous, and (3) it was unecessarily aggressive and polarizing. However, the book had several points that resonated with me, giving a swath of great advice, and made a strong stance against diet culture and weight-based discrimination.

This post is the second of two that breaks down Lindo Bacon’s key points made in Health at Every Size. Last post, I broke down the first five major points, and in the this one, I discuss the rest.

Breakdown of Health at Every Size: The Surprising Truth about Your Weight, Part 2

Key Point #6:

We are victims of fat politics and there is no evidence that obesity is dangerous to your health.

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Lindo Bacon opens their argument by attacking the statement that thousands of Americans will die from obesity. They claim that the science on obesity is flawed and that on average, overweight people actually live longer than normal weight people.

They say that the obesity epidemic was manufactured, that obesity does not increase the risk of death. They call it the “Death by Fat Myth”. They go on to attack several linkages health professionals have established between diet, weight and disease including hypertension, diabetes, cancer, and atherosclerosis. They argue that fat can actually protect you from disease claiming that there are many conditions that are observed in normal weight people that are less common in obese people such as cancer, chronic bronchitis, anemia, type 1 diabetes and osteoporosis.

This argument is frustrating because they are using data to reach inappropriate conclusions. I struggle to follow the logic because the diseases they list are not caused by being thin – so extrapolating that obesity protects you from them does not make sense. The thinness related to these conditions may be induced from smoking (Cancer, chronic bronchitis), lack of nourishment and eating disorders (anemia, osteoporosis) or a myriad of other reasons. This is where their critical thinking and argumentation really comes under scrutiny. They claim that being overweight can protect you from certain diseases, those diseases more commonly seen in thin people. The examples they use are flawed because the thinness is a result of other pre-existing mental, health or economic conditions. They are not a result of thinness, but rather thinness may be a result from the pre-existing condition.

For example, they argue that being obese can potentially protect you from type 1 diabetes. This kind of argument is dangerous and scientifically flawed. This is a dangerous claim because obesity is related to type 2 diabetes. The reason why that claim is scientifically flawed is that thinness is often a result of type 1 diabetes. Thinness does not by any means induce type 1 diabetes. In fact, type 1 diabetes cannot be prevented by weight regulation or anything that we are aware of for that matter. Therefore, obesity cannot prevent such diseases.

For those interested in the relationship between weight and longevity, please see Dr. Michael Gregor’s Obesity Paradox short video here.

They argue that your genes play a big role: that “genes determine the result of the habits you choose”. If that were true, then environmental influences (like advertising and politics that they argued about earlier) are not a big deal. This is the old debate about nature versus nurture. The likely answer is that they both play significant roles. However, a lot of environmental factors can trigger genetic factors as well. Someone genetically vulnerable to cancer may not get cancer, but under certain environmental conditions, they may be at greater risk. Someone not predisposed to cancer may get it from repeated exposure to carcinogens. We cannot say exactly how to weigh genetic and environmental influences because they vary from circumstance to circumstance, person to person. So, I cannot agree with their analysis.

They say that being obese or thin is mostly a result of your genetic predisposition of storing fat. They also argue that everyone cannot lose weight (and maintain the weight-loss) by eating healthful food and regular exercise (as well as other methods).

They attack the experts and say they may be influenced by cultural norms or use shady science tactics. They argue that all they are doing is fear mongering about weight – that the weight-loss industry is worth a lot of money – “fearmongering about weight is worth billions”.

Again, the argumentation here is aggressive, and unconvincing.

Key point #7:

Respect yourself, regardless of body-size.

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I really enjoyed the message here about self-hate and your body shape. It is true that people “remain stuck to the body they’ve grown to loathe”. As if hating your body should be the motivator to change. They say that change should come from valuing yourself so much that there is invested interest to change. If you love yourself, you will be motivated to treat yourself well, which may include exercising more and eating healthier foods.

They make another good point about how we frame healthy foods in our diets. If we are eating salads as a tool or chore for weight-loss, then how will we be able to actually enjoy the flavours of all the fresh, vibrant produce it contains? Furthermore, being thin may not result in getting a supportive partner, more friends or acceptance by your family. People have all these ideas about what being thin will do for them, providing a sense of false hope.

In response to that, I do believe being thin as a result of a healthy lifestyle will reduce your risk of certain diseases and make you feel good. I am not thin, per se. However, I have found that by losing weight I feel better. I feel lighter. It is easier to move, hike, jog, run, bike, walk around, get up, sit down, sleep. It is easier on my joints, I have less swelling. For me, having a healthy weight induces a much better quality of life. Building muscle mass makes me feel strong, life is easier, it is easier to do almost everything when you go from little muscle, to just a little more. When I gain weight, it is because I am lazy and lack self control – something they say is a myth. They say that “thin is better” is another myth – I just need to disagree here. I am not thin – but being thinner than I was, has been life-changing.

In their study, some patients claimed their obesity started with some childhood trauma, a self-representation about motherhood, or a desire to be noticed by taking up more space. These psychological frameworks reinforce weight-gain. So, their obesity is closely tied to their mental health or worldview. Of course, a program that addresses mental health, self-acceptance, self-esteem and letting go of their obsession with weight would help get positive results. Addressing mental health may be a gap in obesity awareness. However, by no means does this disprove modern understandings about the science of weight – as they imply.

They want us to avoid negative talk, frame our thoughts differently, seek support and to seize the moment, pieces of advice that should resonate with us all.

Key Point #8:

Eat when you are hungry.

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Here they give you several guidelines: eat delicious food, pay attention to what you eat, satisfy your hunger, and address emotional eating. I like this message, however, earlier in the book they adamantly argue against the use of rules in your diet. Here, they seem to be giving us rules, but call them guidelines instead.

They urge you to keep a journal to understand your hunger, fullness, emotions, feelings, and satisfaction. Without journaling, they assert, you may not be able to notice certain feelings or sensations you have from eating. Becoming sensitive to how your body responds to food is at the heart of the book, and the concept of intuitive eating.

Great points. I agree with the core message to eat when you are hungry and don’t deny your hunger as a result of weight regulation efforts. Eating should be in response to how your body feels, rather than avoided and shamed as a result of your weight goals.

Key Point #9:

Live well to be healthy.

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Here they urge you to seek a healthy lifestyle.

They want you to reframe exercise. When on the diet and exercise regime, your workouts may seem to be a chore. Exercise rather should be fun and does not need to be at the gym necessarily, if you don’t enjoy it. Just be active by doing things like delivering mail in person, going for walks, and stretching.

They urge us to build in activity throughout the day, even by things as little as throwing away your remote control so you must change the channel manually. Moving can be fun, the outdoors is beautiful and there is so much to see, smell and touch in this world.

They want us to address the resistance we have to physical activity albeit feelings of humiliation, ridicule, injury, or self-confidence.

Here, they also advise us to eat a whole-foods, mostly plant-based diet. Great advice. They claim that by doing so, you could reset your “set-point” weight to a healthier level. So, I guess what you eat does matter – to maintain a healthy setpoint weight. Something I they argued did not matter much earlier in the book. Earlier on, they argued that what you eat does not really matter when it comes to weight, now they are taking it back. I found this book to be full of mixed messaged like this. That kind of communication is dangerous. Anyone could pick up this book, skim through some main points, then totally get the wrong idea.

They tell you exactly what most dietitians and nutritionists would (the same health professionals they attacked earlier on claiming their science is flawed) – to eat a variety of food, primarily plants. They say that intuitive eating will only get you so far, that “some conscious effort” is needed to ensure you get all the appropriate nutrients. For example, if you are lacking iron or zinc, your body may not give you any urge to eat foods high in them.

They have more rules here. Something they told us to avoid early on. So, they call hem guidelines. That really bothers me because it seems hypocritical and is more about semantics. They attack the health and wellness community by their use of rules, then proceed to give us many rules under the guise of “guidelines”. However, these guidelines are great, the common type of advice that you hear from many mainstream health professionals:

  • Eat real food (not processed crap)
  • Enjoy what you eat
  • Eat a lot of plants
  • Be active

Key Point # 10:

You can change your taste.

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They author argues that you can change your taste. If you crave junk food, fast food, or unhealthy food, rather than healthy foods, you can change that. Don’t eat healthy food because you have to. Don’t be restrictive and forceful with your eating habits, rather be open and try new, healthy things.

They claim that we can break old habits. We can change how we perceive meals and food and explore what plants can offer your taste buds.

I think this is true. We can change our taste buds. By eating a variety of different plant foods, we can explore a much more diverse and vibrant diet and discover insatiable foods that we may not have considered previously. In my experience, I never liked soy milk, tomatoes or peppers, but grew to love them by exploring different ways of using them.

Key Point # 11:

Society needs to change their perception about weight.

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The author is really trying to change the public’s perception about weight. They say that weight is not the issue, healthy living is. Rather than attacking weight, address health – being active and eating a whole-foods, mostly plant-based diet.

They seek to break the stigma about weight, saying that the science does not support society’s assumption about obesity. They claim that the war on fat was lost, that attacking weight resulted in eating disorders and an unhealthy relationship between our society, diet and weight.

They claim to have the solution, to address lifestyle factors rather than weight to destigmatize fat and shatter the stereotypes around weight. To do this we need to shift from a weight-centered view of health to one that celebrates a diversity of body sizes. They urge the scientific community to fix their broken method of weight-related research and disentangle relationships between government, industry and universities that negatively impact the health of citizens.

They urge us to avoid supporting the processed food industry who sell us empty calories and unhealthy junk. They urge policy makers and industry to address social inequities when it comes to access to information and healthy food.

Finally, they urge health professionals and the public to stop making weight the central issue, but rather to address lifestyle factors. They are disappointed with the extent that weight shaming, and weight related discrimination proliferates in our society.

One issue I had was with their argument that weight related disease is more influenced by genetic factors than weight. This may be true, however, if you are genetically predisposed to weight related diseases, then losing weight should greatly reduce your risk. Yes, genetics plays a role but lifestyle factors related to weight, and your weight specifically can be mitigating factors for weight-related health conditions.  

I appreciate what the author is doing in this chapter, urging health professionals to destigmatize weight and rather address lifestyle factors. Maybe this is a better approach, I don’t know. However, I think the route they took to get there was flawed, namely by attacking the science of obesity poorly.


This book was interesting. As frustrated as I am with the argumentation, Lindo Bacon makes several great points and impactful messages.  I agree with all the advice about healthy living – which is the same advice I hear health professionals say when they urge people to find a healthy weight (especially to obese people who need to lose weight). However, I disagree with how they got there.

They say to follow the science, but only the science they prescribe you, as mainstream science is flawed. However, I found their use of logic in their scientific arguments to be lackluster, stretching evidence beyond its applicatory scope. They say things like obesity could protect you from type 1 diabetes, chronic bronchitis and cancer. They claim that overweight people live longer. These are all claims based on unreasonable extrapolations, poor comparisons, and bad logic. Presenting them to the public in such a fashion is dangerous.

Thank you so much for reading this summary of Lindo Bacon’s Health at Every Size. I sure found this interesting. I am much more interested to hear what your thoughts and opinions are. If you have any feedback, comments, or ideas, please share them in the comment section below. I am sure it will create an interesting dialogue.

If you enjoyed this post, please like and subscribe, I really appreciate it when you do. You can also follow me on Twitter @interestpeaks.

Book Breakdown Part 1: Lindo Bacon’s Health at Every Size

Health at Every Size Book Breakdown Part One

By Cory Davis

On January 23, 2021, I wrote a book review for Health at Every Size (2010) by Lindo Bacon (here). I gave this book a 3/5 for three main reasons: (1) the argumentation and logic was not convincing, (2) some of the messages were dangerous, and (3) it was unecessarily aggressive and polarizing. However, the book had several points that resonated with me, giving a swath of great advice, and made a strong stance against diet culture and weight-based discrimination.

This post is one of two that will break down Lindo Bacon’s key points made in Health at Every Size. It will breakdown the first five major points, and in the next one, I will discuss the rest.

Health At Every Size: The Surprising Truth About Your Weight: Bacon, Linda:  9781935618256: Books - Amazon.ca
Health at Every Size Book Cover

Prior to reading this breakdown, please note that Lindo Bacon prefers to be referred to by the gender-neutral pronouns “them” and “they”. So, please be cognizant of this when reading this post as when I state that “they argue”, or “they claim”, I am referring to Lindo, rather than two or more authors.

Breakdown of Health at Every Size: The Surprising Truth about Your Weight, Part 1

In this breakdown, I will share with you the first five key points the author makes in this book. Some of which I agree with, others, I do not.

Key Point #1:

You body has a built-in mechanism to regulate your weight.

diet, fat loss, weightloss, liposuction, woman, concept, slim, body, shape, slimming, stomach, measure, measurement, obese thin, success, obesity, scale, idea, fit, surprise, care, female, fruit, achievement, adult, beautiful, dieting, figure, graphic design, line, font, illustration, computer wallpaper, graphics, happiness, art, flower, clip art
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The first chapter introduces us to the concept of a “fat-meter”, that our bodies have a natural weight which it gravitates towards called your “set-point”. They describe it as “built-in mechanism” that tells your body to boost your metabolism after over-eating and weight gain or slow it down after under-eating and lost weight. This explains why people who diet often gain weight afterwards, rendering it pointless. However, if you are struggling to maintain weight and are considered over-weight, this meter may not be functioning correctly and cannot correctly determine your setpoint. They promise the reader that after completing this book you will be able to reset your fat meter to naturally reach your healthiest weight.

They argue that your setpoint weight is mostly genetic. Dieting reminds our bodies of famine which forces them to store fat more easily. Your fat cells communicate with your body to regulate its functions. When you lose weight below a setpoint, your body recognizes it as a threat. By dieting and losing weight below that setpoint, your body may respond by increasing it to protect itself.

They object to diet culture here, a point that I agree with. Fad diets can be dangerous and ineffective for long term weight loss. Better advice would be to live a healthy lifestyle rich in exercise, social activities, and whole foods, as the author gives later in the book.

I am skeptical about the “set-point weight” concept, but do believe there are grains of truth in it. Our bodies do compensate for under-eating, and starvation. However, it may not be so simple as to say that you have a natural setpoint weight that your body reverts to. Weight is a complex, and an incomplete science that varies across cultures, genetics and lifestyles. I think it may be a useful term when explaining certain characteristics about how your body responds to weight but lacks grounds to say it is as simple as they imply.

Key Point #2:

If you struggle with weight, your weight-regulatory system may be broken.

Weight Scales Icons - Download Free Vector Icons | Noun Project
Retrieved from Noun Project

If someone struggles with weight, the author claims that their fat meter may not be working. This is because they are not driven to eat by hunger anymore. Rather, they are driven to eat by boredom, sadness, anger, loneliness, or a host of other emotions or circumstances. It could also be that past behaviours increased the setpoint weight making a thinner build much more difficult to achieve.

They argue that eating in response to hunger will not make you gain weight, but denying or ignoring hunger will force your body to protect itself by storing fat more efficiently.

They identify that Americans do not enjoy food as much as other cultures. Where Americans would call chocolate cake a guilty pleasure, the French call it a celebration. They imply that the reason French people suffer less heart disease and obesity than Americans is not only what they eat, but also how they eat. Part of this argument resonates with me. Food should be fun and enjoyable, not shameful and resentful.

They argue that we maintain our natural healthy setpoint weight when we actively respond to what our bodies tell us. When we challenge this process, we damage the systems that regulate it.

They categorize people into two groups: restrained and unrestrained eaters. They point out that researchers found that unrestrained eaters are more sensitive to hunger than restrained eaters. So, restrained eaters will need to be deprived of food for longer in order to feel hungry.

They argue that restrained eaters are in danger of gaining weight. Restrained eaters when faced with pizza, will eat several slices when the unrestrained eater is satisfied after one. They claim researchers found that restrained eaters, when already full, are more likely to order a dessert when enticed by a waitress than unrestrained eaters. The major difference being that restrained eaters engage with food in response to emotion more than unrestrained eaters who respond to hunger and fullness.

I appreciate the reinforcement that we should eat when we are hungry, not as a coping mechanism for various emotions or circumstances.

They attack the notion of labelling foods as good or bad. There are mixed messages here because later chapters paint a clear picture of good food to maximize in your diet and bad foods to avoid. I think the aim here is to get us to reframe how we think about food. Rather than labelling food good or bad, eat what you want but do it consciously, in response to how your body feels. Chips are often thought of as “bad”. However, are they really that bad if you limit your intake to only a small handful on rare occasions? Probably not. If you eat an entire bag impulsively though, you probably wont feel that good afterward. After you eat a salad, you feel light, full, and clean. They are trying to get us to be less restrictive with our eating. If you set yourself a dietary framework or meal-planning regime based on rules and regulations, it may take the fun out of it.

Key Point #3:

Dont trust the experts. An attack on the science of weight-loss.

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They attack the science of weight-loss by saying that there is no “scientific evidence to support any theory of how to lose weight and keep it off”. They state that diet and exercise only works for a minority of people. They go on to state your failure at weight loss is not your fault and that self blame could get in your way of “what is possible”.

They say you are not completely in control of the factors that contribute to your weight such as when and what you eat or how often you exercise. I agree that we are not in complete control, there are all kinds of factors that influence our behaviour. However, we do have some control, even in how we manage those influences in our lives. Although I should not blame myself for being overweight, it was control, motivation, and support to change my lifestyle that enabled me to drop and maintain it.

I agree with the statement but disagree with the message. It feels like they are telling us to not take responsibility for our personal health and that we are not in control of our own behaviour. It is demoralizing to have someone imply that your internal locus of self-control is unwarranted, that we should relinquish responsibility of ourselves to the environmental and genetic factors that influence our behaviour.

They justify their logic by pointing to the hypothalamus, a small but important part of the brain that regulates your appetite. It may nudge you when you see junk food that you cannot resist. They say “it is not your fault” because these urges are not completely in your control, and are so powerful that they can ruin diets. They say that few people are able to overcome this.

They contest that if you eat less food you will weigh more because of your biology’s defence against starvation. They say that a study showed that women who diet over the long-term return to their original weight even if they stick to it. Furthermore, those women ended up having a larger abdominal circumference. They use this as evidence that those who reduce their calorie intake would just gain it back anyways even if they stick to their diet. There is a grain of truth here but there are huge problems with the message.

I found the study they were referring to (Howard, et, al, 2006), even though they did not properly cite it. They just say that according to a study from the Women’s Health Initiative, eating less calories does not make you lose weight. There is a glaring problem with Lindo Bacon’s analysis here. The study was conducted over the course of about eight-years, in age ranges where increasing abdominal circumference in women is expected. The science suggests that “both time (chronological aging) and ovarian aging” contribute “to substantial changes in body composition (fat and skeletal muscle mass) and waist circumference.” (Sowers, et al., 2007), which supports conclusions already well established in the literature such as in Noppa, et al. (1980), and Shimoka, et al. (1989). The waist circumference increase was not a result of your body’s weight regulation system responding to a lack of calories, rather it is a direct result of aging. In fact, the Women’s Health Initiative Study (Howard, et al., 2006) found that over the course of years, the women on the lower fat diet did not gain weight. That is great, because women tend to gain weight over these years (Sowers, et al., 2007). So, the diet actually worked. Where most women in those age ranges would gain weight, the participants in the Women’s Health Initiative did not. For this reason, the logic that Bacon uses in their argument is unconvincing.

It is also confusing because later on they argue that to reset your “fat-meter” and achieve a “healthier” body and weight, you need to eat better, and be more active. They point to low-caloirie, low-fat foods as a tool to get there. Exactly what they are arguing against in this chapter.

They go on to say that there is no evidence to suggest that exercise will make you lose weight, that research shows that people on exercise programs do not lose significant weight in the long term. They say things like studies have shown that sedentary people on average only weigh about five pounds more than those who exercise regularly.

The thing with statements like this is that people can be “thin” for many unhealthy reasons. Smoking, drinking, cancer, eating disorders, and drugs can all effect weight causing people to be thin. Weight problems are not the only symptom of sedentary lifestyles, all kinds of other health related problems are associated with that. In November 2020, the World Health Organization said that 5 million deaths per year could be avoided if people were only “more active”. Later on in the book, Lindo agrees that physical activity is good for your health.

However, here they say that people living sedentary lifestyles do not weigh much more. Lindo suggests that active people are not thinner because they are active, but maybe because they are better at managing stress or some other reason. They give lots of alternate possibilities such as exercise makes some people eat more so they don’t get the benefit of weight loss.

However, there is a clear indication that physical activity can play a role in maintaining weight-loss weight loss. According to Swift, et al (2013), physical activity “has a major role in the amount of weight regained after initial weight-loss”, that significant exercise increases the amount of weight-lost people can maintain.

Key Point #4:

What you eat does not matter when it comes to weight-loss, but what you eat does matter when it comes to weight loss.

No Food Or Drink clipart free image
Retrieved from Pixy

So, we unpacked a lot in so far. Here they reaffirm that we should understand by now that dieting is not likely to encourage long-term weight loss, but rather weight gain. They say things like “What you eat – at least from the perspective of weight loss – probably doesn’t matter that much”.

But then they acknowledge that they are not surprised that what you eat is associated with weight gain. What? They just said that it does not matter what you eat for weight. They attack certain foods – bad foods (recall earlier they said to stop categorizing food as good or bad) like refined carbs and high fructose corn syrup for likely being associated with weight gain.

They claim that what you eat – particularly high fat, high sugar, processed or animal-derived products – will mess up your weight regulation system. This can then cause you to have a higher set-point weight.

Earlier on, they said that your weight does not matter, that overweight people live longer, that most people cannot lose weight and maintain that weight loss, even with diet and exercise. Now, they are saying yes you can lose weight. Changing your diet and exercise is important – exactly what health professionals recommend – but they argue health professionals rely on bad science – and Lindo’s science is good and “clinically proven”.

I really struggle with the presentation and message thus far. There is so much that is agreeable and so much that is not.

For example, they try to get you to stop dieting with rules. Rules like limit processed food, eat high fibre food are not tolerated in their regime. However, they go on to say but you should not eat processed foods and to maximize your intake of high fibre foods. They urge you to avoid artificial sweeteners, soft drinks and fat-free foods as they can mess with your weight regulation system. These sound like rules to me, but they call them guidelines – not rules. This is a matter of semantics, not a reason to attack the entire nutrition and health profession as they do.

Key Point #5:

Industry wants you to eat unhealthy food, and the government is assisting them.

Gesturing(Hand Sign) Business demon (Evil Businessman) showing OK gesture
Retrieved from Pixy

They discuss how corporate marketing impacts our eating habits without us knowing using psychological tricks. Companies “nutri-wash” their products, like Pepsi Co. awarding Diet Pepsi the Smart Spot nutritional seal. They spend tens of billions in marketing and research to convince the public to buy foods. They talk about economic law, how shareholders can sue a CEO if they pursue social responsibility at the cost of maximizing profits.

They discuss food prices and government subsidies. One bushel of corn only cost about four dollars (USD at the time) and contains enough calories to sustain someone for two months (130,000 calories). The reason it is so cheap is that the government subsidizes it. Therefore, agriculture does not operate in a free market like most of the economy, but rather is protected. If a farmer cannot sell their produce for a fair price for certain crops the government will pay the difference. This is an incentive for farmers to grow more of a certain crop, even if it can’t sell.

The meat and dairy industries benefit from the subsidies too because they get cheap feed for their animals. They say that government subsidies do not cover many fruits, veggies and legumes, so schools find it difficult to get healthy food. So, rather than fruits and veggies, children get meat and dairy.

Because of the incentives, industry grows exuberant amounts of corn to sell to the animal farming and high fructose corn syrup sectors.  Most fast-food menu items have corn in it – from fries fried in corn derived oils, to breaded chicken nuggets, to high fructose corn syrup in sodas. Just because it is so cheap and they can pass those savings onto you.

The second most subsidized food is soy – which could be healthy. However, most soy is converted to oil to make hydrogenated oils, soy lecithin, and other products – but is mostly processed and refined. This is opposed to using soy for tofu, tempeh or whole.

These policies and economics create a system that ensures unhealthy food that makes you gain weight is cheaper than healthy food.

They talk about how processed food (with high fat and high sugar) release opioids in your brain, which is pleasurable and encourages you to eat more. Industry is interested in you eating more because it is good for business. Getting you to eat high fat high sugar food is good for business. Maybe that is why only around 2% of food advertising is for fruits and veggies.

The food industry heavily influences the health-related organizations and health professionals. They donate to non-profits and sponsor professional events where they can disseminate information, internal studies about their products that may suggest they are healthy but only in a narrow sense.

Subway can now use the Fighting Heart Disease and Stroke Logo, Kellogg’s Frosted Flakes has a Heart Healthy Logo. Coca-Cola donated 1M$ to a dentist organization and partnered with the American Academy of Family Physicians.

They attack the Dairy Industry, and they do it very well. The claim that “You Need Milk” is nonsense. They make a case that milk is not even good for you. That is true for most people, as over half the world has some degree of lactose intolerance.

They say we need to shift the blame. Industry blames the individual for overconsumption because nobody forces people to buy junk food. But they argue that because we believe in freedom of choice. Therefore, government should play the role to educate people and create incentives to eat healthy food.

I agree with a lot of the argument here. However, they frame industry in such a negative light, as if they want you to be unhealthy. As if political and economic forces have some plot against humanity. I dont think these kinds of attacks are warranted, nor does it further their goals. Industry is made up of people, they are not evil. However, I do agree that the system is not robust enough to promote and incentivise healthy foods, making them accessibile for the public. This is not because government is corrupt, rather that the system is complex and difficult to maneuver. If the public wants policy changes, we can vote that in. That is the power of democracy. So, we (the public) are also responsible. Governments in North America do not typically make decisions at will. Decisions are made through legislation (which is developed through public and stakeholder engagement), public consultation, and advice from experts. Decisions are a reflection of modern societal norms, beliefs, goals and values.

I dont think that attacking governments and industry does the cause justice. Rather, these groups are stakeholders in the interest of our discussion. Therefore, we need to treat them as stakeholders, which means being inclusive to them by establishing respectful relationships where innovation can flourish. By attacking eachother, we are polarizing people, dismantling relationships, and pitting people against eachother. Chaos is not the way forward, rather tolerance, understanding, diplomacy, diversity of perspectives and unity is.


Lindo Bacon makes many good points, creates an interesting dialogue and has lots of good advice. However, the argumentation and logic was difficult for me accept. I disagree with some points and agree with others. I also found some mixed messages, resulting in mixed feelings about the book.

Please stay tuned for my next post, where I will break down the rest of the key points made in Health at Every Size.

Thank you so much for reading this breakdown. If you enjoyed this post, please like it and subscribe, or follow me on Twitter at @interestpeaks. I always appreciate it when you do.

As always, I found this discussion interesting, but I am more interested in what your thoughts and opinions are. If you have any comments, questions, or concerns, please share them in the comment section below. I am sure it will create an interesting dialogue.


Howard, B. V., Manson, J. E., Stefanick, M. L., Beresford, S. A., Frank, G., Jones, B., … & Prentice, R. (2006). Low-fat dietary pattern and weight change over 7 years: the Women’s Health Initiative Dietary Modification Trial. Jama295(1), 39-49.

Noppa, H., Andersson, M., Bengtsson, C., Bruce, A., & Isaksson, B. (1980). Longitudinal studies of anthropometric data and body composition The population study of women in Göteborg, Sweden. The American Journal of Clinical Nutrition33(1), 155-162.

Shimokata, H., Andres, R., Coon, P. J., Elahi, D., Muller, D. C., & Tobin, J. D. (1989). Studies in the distribution of body fat. II. Longitudinal effects of change in weight. International journal of obesity, 13(4), 455-464.

Sowers, M., Zheng, H., Tomey, K., Karvonen-Gutierrez, C., Jannausch, M., Li, X., … & Symons, J. (2007). Changes in body composition in women over six years at midlife: ovarian and chronological aging. The Journal of Clinical Endocrinology & Metabolism92(3), 895-901.

Swift, D. L., Johannsen, N. M., Lavie, C. J., Earnest, C. P., & Church, T. S. (2014). The role of exercise and physical activity in weight loss and maintenance. Progress in cardiovascular diseases, 56(4), 441–447. https://doi.org/10.1016/j.pcad.2013.09.012

World Health Organization (2020). Every move counts towards better health – says WHO. Retrieved 23 January 2021, from https://www.who.int/news/item/25-11-2020-every-move-counts-towards-better-health-says-who

“Alone in The Universe”: John Gribbin’s Argument for Why Most of the Milky Way Galaxy is Uninhabitable

By Cory Davis

This is a breakdown of John Gribbin’s argument as made in his book Alone in the Universe: Why Our Planet is Unique (2011) for why most of the Milky Way Galaxy is uninhabitable.

Alone in the Universe -- Why Our Planet Is Unique.jpg
Alone in the Universe: Why Our Planet is Unique (2011) by John Gribbin

On December 19, 2020, I wrote a review of this book, giving it 4/5 stars. I thought it was a fun thought experiment which made me wonder and ponder our existence in the universe. If you are interested in checking it out, please find it here.

Later on I tried to summarize the author’s consicely into 12 premises and a conclusion for why we are alone in the Milky Way Galaxy as a technological civilization. If you are interested to check it out, please find it here. His argument first reduces the the amount of stars that could harbor life from 100% of the Milky Way to just 10%, based on metallicity and location. This blog post breaks down his argument for why.

Chapter two of Alone in the Universe is dedicated to explaining why the Milky Way is “special”. This chapter outlines why our galaxy is able to accommodate technological civilizations, whereas many galaxies in the universe cannot. This can simply be inferred by their metallicity content. However, even in our special galaxy, conditions are violent and often inhospitable to life, even in the most habitable regions.

Accumulating Heavy Elements in the Galaxy

Galaxies like the Milky Way formed within the first three to four billion years after the big bang. Through many generations of stars in the Milky Way, the content of heavy metals built up, accumulating to the point where it could form rocky planets. The process of building up heavy metals took billions of years leading up to the birth of our solar system. Therefore, it must have taken billions of years to develop conditions that allow for the evolution of life.

  • 3-4 billion years after the big bang – galaxies like the Milky Way form
  • 6-9 billion years after the big bang – the Milky Way develops enough heavy metals to sustain rocky planet formation. Our sun is born
  • 13.2 billion years after the big bang – complex life begins to emerge on planet earth

It took our solar system around five billion years to produce complex life, followed by technological civilization. If this is a regular amount of time it would take to do that, then we could be one of the first in the Milky Way.

As noted in the “cosmic calendar” (see previous image), it was not until mid-May that the thin disk of the milky way formed. The development and accummulation of heavy metals occurred in the galaxy’s disc. This disc produces stars that make heavy elements essential for complex life, rocky planets and technology.

The disc is a feature of spiral arm galaxies. Most galaxies are not this type, and the Milky Way wont be one forever. The Milky Way may become elliptical, through a collision course with the Andromeda galaxy billions of years in the future.

So, how did heavy metals build up over time in the Milky Way’s disc? As noted above, it was through the succession of generations of star birth and death.

Larger stars than the sun [at the ends of their lives] will collapse creating heat and pressure fierce enough to fuse heavy elements like nickel and iron then blow a bunch of it away in clouds of dust. The biggest stars in the universe will create and disperse even heavier elements in supernovae explosions. John Gribbin highlights the importance of supernovae. He says that supernovae are what create the heavier elements like iron. When our sun dies, collapsing into a white dwarf, it will only be able to fuse together elements up to carbon and oxygen. Whereas more massive stars will collapse further and create materials required not only for rocky planet formation, but also for essential biochemical reactions.

Supernovae and time are required for technological civilization as the metallicity (or amount of metals) in stars increases over generations. However, too much metallicity could be a bad thing. Stars with higher metallicity, are more likely to have a large-Jupiter planet orbiting close to it. These large “Hot Jupiter’s” would orbit as close as earth is to our sun or even closer, which would disrupt orbits of earth-like planets close by.

The Galactic Habitable Zone

Currently, there is a narrow region within the Milky Way Galaxy that has enough metallicity to sustain rocky planet formation. This region accommodates 10% of all stars in the Milky Way. This is what some call the galactic habitable zone. The area is thin, short in width, not near the galactic centre, or the outer edge.

  • The outer part of the galaxy consists of old stars that formed 10 billion years ago (twice the age of the sun) that don’t even have 10% the metallicity of ours. You likely need around 40% the metallicity of our sun to develop rocky planets.
  • The galactic centre has a bulge around it that make up most of the stars in the galaxy. The bulk of the stars in the bulge are old and low in metal content. There are few younger stars in there. Because it is so dense and close to the centre, the radiation would be far too high to accommodate life, reducing the probability of life occurring even more. The number of encounters with other solar systems would also result in many more extinction level impacts.
  • The galactic habitable zone is a thin disc in between the outer edge and inner bulge no more than 1000 light years thick. This area contains young stars like the sun. It is currently the only area within the milky way producing new stars and enriching it further with heavy metals.

The galactic habitable zone idea was put forward due to the link between metallicity and the likelihood of forming planets such as Earth, Mars, or Venus. However, it is not constant, expanding over time. Charles Lineweaver (Senior Fellow at the Planetary Science Institute, Australian National University) postulates that the galactic habitable zone emerged roughly 8 billion years ago from a ring roughly 26 thousand lightyears from the galactic centre. Now he postulates that it extends from about 23 thousand lightyears to 29 thousand lightyears from the centre.

However, the galactic habitable zone depends not only on metallicity, but also on the frequency of potential hazards that star systems would encounter when they travel around the Milky Way Galaxy. Supernovae and the supermassive black hole at the galactic centre are two of them:

  • Supernovae are a hazard.
    • Supernovae are more common in the galactic centre because it is more dense.
    • They likely occur on average about once every 100 million years in our galaxy and could be devastating to life on earth even from across the Milky Way. The author says that it could be possible for a supernovae to even sterilize an entire galaxy – but it has been pointed out that they are very short-lived. So, the side of the planet facing away from it could be shielded from the more harmful effects although there will be setbacks, such as a large hole in the ozone.
    • Supernovae were more common in the earlier galaxy, which could be a reason that intelligent life took so long to form on earth. So, it would be easier for intelligent life to form now by not having as many gamma ray burst events slowing things down.
  • The supermassive black hole at the galactic centre is a hazard.
    • Radiation hazards don’t just come from supernovae, but from the galactic centre itself where the supermassive black hole is located. Although it is not very active today, there are signs it was more active in the past.
    • Active black holes studied in other galaxies show that when they swallow material (such as stars or gas clouds), it gets sucked in at an extremely high speed and results in intense radiation shooting into the bulge. Unfortunately, stars in the bulge tend to have elliptical orbits around the black hole, so they end up coming very close to the centre. Either way, any planet bombarded with this kind of radiation will suffer immensely.

Most of the galaxy is thus uninhabitable. Only the thin disc has the metallicity required to sustain the evolution of technological life. However, the galactic habitable zone is still a violent, life-threatening place to be.

The Galactic Habitable Zone is a Dangerous Place to Live

Passing Through the Galaxy’s Spiral Arms

The sun is located about 27,000 light years from the middle of the milky way, and takes roughly 225 million years to make a complete orbit. So, since the sun formed, it made about 20 complete orbital rotations around the centre of the galaxy. We are currently near the inner edge of a spiral arm called the Orion arm, or otherwise known as the Local Arm. The author notes that spiral arms are not permanent, that they get smoothed out over time – it just seems permanent since we are just a snapshot in time, as he puts it – “like snapshots of the spiral patterns of coffee”. But the bulge can also kick back up a spiral pattern, so they may come and go and set of a process of star formation in the arms when they do. This process is very good at mixing metals in the thin disk of the galaxy when it occurs. The spiral density waves, like the one that makes up the Orion or Local arm sent off from the bulge actually moves slower than the stars do. So, we are not just existing within the Local Arm, we are literally just about to pass through it.

Spiral arms are where supernova occur. If the solar system was impacted by one, it could destroy our ozone layer and cause serious harm to life on earth. If the solar system was within 30 light years of a supernova explosion, it would likely destroy most life on the surface. So, the likelihood of an extinction event caused by a nearby supernova explosion increases as we go through spiral arms. That is because more supernovas occur in them.

So, stars closer to the bulge would pass through more arms over time because they are closer together near the middle. We are further from the middle. So the risk of extinction by supernova or other hazards in the spiral arm decreases the further away from the centre you are located.

Last time the solar system passed a spiral arm was about 250 million years ago. The Palaeozoic era ended around 250 million years ago in a mass extinction. This could be related to the spiral arm encounter, or it could not be. But that is just another indicator that some regions in the milky way are more accommodating to life than others, and the probability of technological life developing or continuing to exist varies depending on where you are located in space and time.


The problem with comet impacts like the one that killed off the dinosaurs is that they could potentially sterilize a planet of all complex life. If the comet was larger than the one that killed the dinosaurs, it could have. But what if the comet was much smaller? The trajectory of evolution would be vastly different and we would likely not be here today to talk about it.

Where there are lots of comet-impacts, these extinction events would not provide enough time to evolve intelligent life.

We are surrounded by a massive Oort cloud around our solar system, presumably most star systems are. The Oort cloud is a halo of rocky and icy debris with trillions of pieces larger than one kilometer in diameter, and billions of pieces over 20 kilometers in diameter.

A close encounter with any large body like a solar system or black hole could perturb the Oort cloud sending them toward our sun, where earth is in its path.

  • This will be much more common in the bulge where there is a higher density of solar systems
  • This will also be more common in the spiral arms where the density of gas clouds would give the Oort cloud a “hydrostatic jump”

We are on a collision course with another solar system right now. The star Hipparcos 85605 will pass by our solar system very closely within the next 250 to 500 thousand years. The star Gliese 710 will pass by in approximately 1.3 million years. Both of these encounters will interact with our Oort Cloud, increasing the risk of impact with the earth.


We are not just located in a good spot in the milky way, we are in a good time as well. Life most probably occurs in the galactic habitable zone and becomes exceedingly less likely the further you travel out. So, for an intelligent civilization to colonize or explore the galaxy for life, they would only need to reach 10% of the stars. This makes that Fermi Paradox question more impactful. If we could practically send robots (like Von Neumann Probes) to explore the galaxy, it would take much less time to explore the the galactic habitable zone than the entire thing. So where are they?

This discussion has all been about the Milky Way, but what about other galaxies? About 80% of other galaxies are fainter, star birth and star death  is occurring less frequently – so the process of increasing metallicity is weaker, possibly too weak for earth like planets. From observations, only about 20% of galaxies seem to have the metallicity required for rocky planet formation. 

Final Thoughts

Do I agree with the author’s conclusion? Well, I can agree that the probability of complex life should decrease where the frequency of hazards increase. I also agree that the probability of complex life decreases the further away from the galactic habitable zone you are interested in. However, it accommodates 10% of the stars in the Milky Way. That still leaves between 10 – 40 billion stars to consider as potential systems to harbour life. However, the author easily shreds this down from 10% to 0.06% in his discussion about habitable star systems and types, a topic for a later post.

All in all, I am not necessarily conviced that we are alone in the Milky way, but found it to be persuasive, forcing me to think big and reflect about our place in the Milky Way Galaxy, or even the universe. I could agree that it is possible for us to be alone in the Milky Way as a technological civilization. However, I would not state is as fact. I am not convinced that we are alone as such in the universe, but would that even matter if we are spatially disconnected to the point where we could never make contact?

Thank you for reading this blog post. I had fun reviewing John Gribbin’s argument for the galactic habitable zone and why most of the galaxy is uninhabitable. However, I am more interested to hear your thoughts and opinions. If you have any thoughts, ideas, disagreements, or insights to the topic, please share them in the comment section below.

If you enjoyed this post, please give it a like, or subscribe. You can follow me @interestpeaks on Twitter too. Please stay tuned! I will return later to discuss John Gribbin’s argument why most stars systems and types are uninhabitable in the Milky Way galaxy.

“Alone in the Universe”: Breakdown of John Gribbin’s Argument for Why We Are Alone in the Milky Way Galaxy

By Cory Davis

This is a breakdown of John Gribbin’s argument as made in his book Alone in the Universe: Why Our Planet is Unique (2011).

Alone in the Universe -- Why Our Planet Is Unique.jpg

On December 19, 2020, I wrote a review of this book, giving it 4/5 stars. I thought it was a fun thought experiment which made me wonder and ponder our existence in the universe. There were four reasons that I did not give it a 5/5: (1) there was no summary of the argument, (2) there was no clear outline about why it is important, (3) the conclusion was extreme, and (4) the title of the book is not honest.

For those of you who felt the same, or are just curious, I will break down John Gribbin’s argument for why we are alone in the Milky Way Galaxy. The conclusion of the book is not that we are alone in the universe as you may have inferred from the title, just that we are alone as a technological civilization in our galaxy.

This is one possible solution to the Fermi Paradox, which poses the question that if technological civilizations are common, where are they? John Gribbin argues, we cannot detect them because they are not there.

The Argument

The argument here has been simplified drastically into 12 premises and one conclusion for the purpose of this post. In later posts, I will elaborate on each premise to provide you with context.

#1 Alien technological civilizations are not close enough in time or space to detect.

  • We cannot detect them now, therefore (1) they are either not here, (2) are not here yet,  (3) have been here and are already dead, (4) have never been here (5) will never be here, or (6) are so far away that we cannot detect them easily

#2 Most of the galaxy is not currently habitable.

  • The galactic habitable zone makes up the region of the galaxy where metallicity is high enough to produce rocky planets
  • Complex life requires heavy metals to function efficiently enough to sustain themselves
  • Technology necessarily requires available heavy metals
  • The galactic habitable zone contains 10% of the stars in the milky way

#3 The galaxy was not always habitable.

  • The galactic habitable zone’s metallicity was built up over time
  • Five billion years ago, it was less metal-rich and had a higher frequency of supernova explosions
  • It took earth almost five-billion years for earth to evolve technological life
  • If that is a usual amount of time, we could even be the first

#4 The galactic habitable zone is a violent place that threatens the long-term sustainability of life.

  • Stars orbit the galactic centre faster than the Milky Way’s spiral arms do.
  • Supernovae occur more frequently in the spiral arms
  • The solar system has passed spiral arms about 20 times since its formation
  • The risk of a supernova encounter threatening life on earth increases as we pass a spiral arm
  • We are surrounded by a massive Oort cloud [of debris] around our solar system, presumably most are
  • A close encounter with any large body like a star system or black hole could perturb the Oort cloud sending them toward our sun, where earth is in its path
  • The spiral arms could also disrupt the Oort cloud with a hydrostatic jump

#5 Technological life can only form in the habitable zone around a star where liquid water can be sustained on a planet’s surface.

  • Habitable zones are not constant, they change over time
  • Water is essential for life
  • The habitable zone also accommodates rock weathering, which is important for the carbon cycle
  • Not all habitatable zones are habitable for complex or technological life
  • Not all stars have rocky planets in their habitable zones

#6 Most stars in the galaxy regardless of the region of the Milky Way they inhabit are inhospitable to technological life.

  • Most stars in our galaxy are red dwarves (M-Stars) (75%)
  • The habitable zone of an M-Star is extremely close to it
  • M-Stars are also much more active than the sun blasting the habitable zone with deadly radiation
  • Large stars are also very dangerous
  • The range of habitable stars consist of K-Type, F-Type and G-Type stars
  • Most stars exist in binary star systems (80%) which threaten stable planetary orbits and result in fluctuating habitable zones
  • Stars that have depleted refractory elements at their surface (like the sun) tend to have rocky planets, stars who have not tend to have gaseous giants in their inner solar system. Only 10% of stars exhibit refractory element patterns.
  • Stars live and die, leaving a temporary window of time for technological life to emerge

#6 Our solar system is uniquely accommodating to technological life.

  • Our solar system has rocky planets in the inside, gaseous planets are on the outside. Most star systems do not.
  • All planets in our solar system orbits in the same direction as the rotation of the sun. Some systems have Hot Jupiters orbiting in the opposite direction which would endanger the stability of orbits in the habitable zone
  • Hot Jupiters, regardless if they orbit in the opposite direction or not are dangerous. 1% of star systems have  a Hot Jupiter.
  • Our solar system is structured and relatively stable, many are full of “violence and drama”
  • Planets usually have elliptical orbits (which could bring them in and out of the habitable zone regularly. Whereas our solar system’s planets have relatively circular orbits
  • Our solar system received a blast of material from a nearby supernova in its very early formation period, enriching it with beneficial materials.
  • Our planets are far enough away from each other that they don’t dramatically influence their orbits
  • Changes in the initial conditions of our solar system formation could have easily led to chaos, or absence of complex life
  • Jupiter has been beneficial for earth, but only in the context of stable orbits

#7 Our planet is uniquely hospitable to technological life, but if initial conditions were slightly different it may not be.

  • We have a relatively low amount of carbon on earth. Most stars with planets have a higher carbon to oxygen ratio.
  • Carbon dominated planets would be built out of carbon materials like graphite on the outer surface and diamond in the centre. The atmosphere would not sustain O2 like on earth, the little oxygen available would form carbon monoxide and methane. The oceans and lakes would be filled with tar
  • We have tectonic plate activity that is rare and essential for life
  • We have a magnetic shield that is rare and essential for life
  • Similar planets to ours are dead – just look at Mars and Venus. So, just because planets are “earth-like” does not mean that they are alive, let alone have complex or technological life
  • We have a very unique moon, without which we would be doomed. The creation of the moon was the same event that led to plate tectonics.
  • The moon does and did produce three critically important things for technological life on earth: tides, planetary tilt and plate tectonics.

#8 The evolution of the Eukaryotic cell was a rare event.

  • The evolution of the eukaryotic cell was an extremely unique event, taking over two billion years to achieve

#9 The evolution of complex life was an extremely rare event.

  • It took an enormous amount of time for simple life to become complex (almost 3.5 billion years)
  • This indicates that evolving complex life is a very long process, as life must slowly compile and gain the required adaptations to do so in the right environments

#10 The evolution of complex life does not guarantee that a technological civilization will emerge.

  • Complex life emerged out of the Cambrian explosion, but that is not the only scenario that could have played out
  • If different kinds of complex life emerged, there is no guarantee that they could accommodate complex structures within their interiors
  • Evolution is not goal oriented, so technological civilization is no guarantee even with complex life and an accommodating planet
  • Any change in the condition of earth during our evolutionary history could have produced radically different lineages
  • Mass extinction events play a critical role in evolution. Slight variations in timing and circumstance could have produced radically different lifeforms, and we would not be here

#10 Human level intelligence is rare, even in the context of complex life

  • Human-level intelligence is rare on earth, and would not have necessarily happened if conditions varied even slightly

#11 There are several looming existential threats to humanity. Some cannot be avoided.

  • Even in our uniquely accommodating solar system, there are several immediately concerning (today to a couple thousand years) existential threats that challenge our long-term sustainability as a technological civilization.
    • Global Warming
    • Ocean Acidification
    • Asteroid impacts
  • There are many existential threats that can and/or will destroy life on earth from
    • Earth will be burned up by the sun
    • Data suggests that a “kill-all-life-on-earth” event should occur roughly once every two-billion years or so. We are overdue for one, and should consider ourselves very lucky.
    • We are on a collision course with several other solar systems, and about to enter a galactic spiral arm.

#12 There is likely no second chances for evolution to produce another technological civilization on earth if we are wiped out.

  • If we are wiped out – earth does not have a second chance to evolve technological life
  • It may not be possible without huge reserves of fossil fuels and accessible ores.
  • We depleted these resources dramatically. To make them accessible again would take billions of years, that the earth does not have.


The last note from the author addresses the Fermi Paradox by stating that technological civilizations are not here in the Milky Way. The reason why we are here, is that a string of highly improbable events occurred, so rare that the probability that other technological civilizations exist in the Milky Way Galaxy at the exact same moment in time as us, is extremely small. Thus “We are alone, and we better get used to it”.

What are your thoughts on the Fermi Paradox? Do you agree with John Gribbin’s argument? Or are you more optimistic? I sure thought it was a fun exercise. But I am more curious to learn about what your thoughts are. If you have any thoughts, ideas, or opinions, please share them in the comment section below. I am sure it will create an interesting dialogue.

If you enjoyed this post, please give it a like or subscribe. You can also follow me on twitter @interestpeaks. Please stay tuned! In my next post, where I will break down the premises of John Gribbin’s argument in more detail.