The Faulty Conclusion of a Gloomy Cosmic Study

A recent scientific paper concluded that life can only exist in about 10% of galaxies. But that conclusion is not warranted from either the facts or reasoning discussed in that paper.

The paper (by Tsvi Piran and Raul Jiminez) was entitled “On the role of GRBs on life extinction in the universe,” and the title referred to gamma-ray bursts. Gamma ray bursts are tremendously strong bursts of gamma rays, the most intense type of radiation. Astronomers detect about one gamma ray burst a day, all from outside our galaxy. A satellite found that these bursts come equally from all directions of the sky, which indicates that they are coming from distant sources outside of our galaxy. The nearest detected gamma ray burst was about 100 million light years away, hundreds of times the length of our galaxy.

Being a very powerful form of energy, gamma ray bursts have probably been a significant trouble maker for the evolution of life in the universe. But how big an effect have they had? Estimating that requires that we estimate two huge unknowns: the rate at which planets get zapped by gamma rays, and the degree to which such radiation bursts might wipe out all or most of the life on a planet.

How Much of a Threat to Life Would Gamma Ray Bursts Be?

First, let us look at the biological effects of different intensities of gamma ray bursts. Following the paper of Piran and Jiminez, we can distinguish between a gamma ray burst that strikes a planet with an energy of 100 kilojoules per square meter (which I'll call for convenience a “class 100” burst), and a burst that strikes a planet with an energy of 1000 kilojoules per square meter (which I'll call for convenience a “class 1000” burst).

Piran and Jiminez say that the “class 100 burst” would cause a 91% depletion of the ozone layer, and that a “class 1000” burst would “wipe out nearly the whole atmosphere.” Piran and Jiminez did not do any independent calculations or research to reach the latter conclusion, because that would involve atmospheric science, which is not their field of study. To support this claim that the “class 1000” burst would “wipe out nearly the whole atmosphere,” they say they are “following Thomas,” and cite two papers by Brian C. Thomas and others, one here, and the other here.

But, in fact, this seems to be a faulty reference, a case of claiming that a scientific paper says something that it doesn't actually say. I examined these two papers by Brian C. Thomas and the rest, and I could find no statement that a gamma ray burst of the “class 1000” type (with an energy of 1000 kilojoules per square meter) would wipe out almost the whole atmosphere. To the contrary, on page 11 of the paper “Gamma-Ray Burst and the Earth: Exploration of Atmospheric, Biological, Climatic, and Biogeochemical Effects,” the authors say this: “Our model is probably not capable of correctly handling the chemistry, heating, and transport for a burst of much higher fluence than 100 kJ m2 [kilojoules per square meter].” That's a level of energy ten times less than the “class 1000” case.

The paper by Thomas and the rest discusses mainly lesser effects such as ozone depletion, and says that the ozone depletion would only last for a decade. The paper also makes clear that the ozone depletion would only be globally catastrophic in the worst way if the gamma ray burst occurred over the equator. Their paper says:

Note that for polar bursts, even in the long term, effects are isolated to the respective hemisphere. Similarly, even for bursts at 45 the opposite hemisphere experiences much less intense effects.

These points are not trivial to the matter being discussed here (whether gamma ray bursts make only 10% of galaxies habitable), because the case of Piran and Jiminez depend heavily on this claim that a “class 1000” burst would “wipe out nearly the whole atmosphere.” In fact, they do not supply any citation or research that backs up such a claim, which is not actually stated by the papers they cite.

I may also note that any galaxy would have plenty of planets or moons that could take the “class 1000” gamma ray hits with relatively little harm. Examples of such places would include planets with thicker atmospheres (which could afford to lose a large fraction of the original ozone and oxygen), and life-bearing moons rotating gas giants, which might be entirely shielded from gamma ray bursts by the gas giants they rotated around. There would also be many planets that would have an inclination or tilt that would result in the gamma ray burst not striking in the equatorial region but in some other region where much less damage would be done. Also, many planets would be protected by dust clouds lying between the planets and the gamma ray bursts.

Cosmic dust (the dark brown bands) tends to block gamma rays

What about the less lethal “class 100” gamma ray bursts? They would have the effect of removing some of the ozone layer in an atmosphere, which would temporarily increase the amount of ultraviolet radiation. The paper by Thomas and others says that this ozone depletion would only last for about a decade. That would be a setback for the evolution of life, but there is no reason to think that it would wipe out even 100 million years of evolutionary progress. Such a “class 100” gamma ray burst might cause a mass extinction, causing many species to become extinct. But such an event would still very probably leave many advanced species surviving. In fact, these “class 100” gamma ray bursts have little relevance to whether a galaxy is habitable.

How Often Would the “Class 1000” Bursts Occur?

Now, let's look at how often these events would occur. On page 5 of their paper, Piran and Jiminez say, “In total 90, 40 and 5% of the exoplanets in the MW would be exposed to a fluence of 10, 100, and 1000 kJ/m2 from GRBs within a period of 1 Gyr.” Here MW refers to the Milky Way galaxy, 100 refers to the “class 100” gamma ray bursts previously discussed, 1000 refers to the “class 1000” gamma ray bursts previously discussed, and 1Gyr refers to a period of a billion years. These numbers are guesses, since we don't really know for sure what causes gamma ray bursts.

These numbers are not particularly gloomy from the standpoint of the prospects of the evolution of life. According to these numbers, there is a chance of only 5% per billion years that a particular planet in our galaxy would get the “really bad” type of “class 1000” gamma ray burst during a billion year period. There would be a 40% chance of a planet in our galaxy getting a “fairly bad” blast from a “class 100” gamma ray burst, but such a blast would be unlikely to set back evolution on that planet by very much.

Let's also remember that Thomas and the others make clear (in the previously cited paper) that gamma ray bursts are only really devastating if they occur over the equator of the planet, and the chances are 80% that such a blast would not occur over the equator of any particular planet. That means the chance of a planet getting zapped really bad by gamma rays is not the 5% per billion years that Piran and Jiminez cite, but an actual net effective chance of only 1% per billion years.

Also, since different solar systems have different planes of inclination, and different planets have different tilts, even the worst type of gamma ray burst would never wipe out life throughout all the planets in a large fraction of a galaxy, because only some of those planets would experience the gamma ray burst above their equators.

Given also the fact (as I discussed before) that Piran and Jiminez have only a faulty reference to back up their insinuation that the “class 1000” gamma ray burst would wipe out most of the atmosphere of a planet, overall these conclusions fail to back up any conclusion that gamma ray bursts are an overwhelming obstruction to the evolution of life in this galaxy or any other large galaxy.

So given that Piran and Jiminez state in the abstract of their paper the gloomy conclusion that “life can exist in only ~10% of galaxies,” how do they justify that conclusion? Very simply, they don't. Oddly, this conclusion is made in their abstract at the beginning of their paper, but is never actually derived or deduced or mentioned in the body of their paper (which violates the rule that abstracts are only supposed to summarize conclusions made and justified in the paper). In their last paragraph, their paper merely says, “We have found that GRBs and in particular LGRBs are life threatening in a large part of the Milky Way as well as in many other locations in the Universe.” But that's a much, much weaker conclusion than the claim that such gamma ray bursts are such a big factor that that they prevent life in 90% of the universe's galaxies.

There is actually no basis for such a claim. Given the wide variety of different habitats that life could have (such as a planet with a thick atmosphere or a moon shielded from gamma rays by the gas giant it orbits or a planet protected by cosmic dust clouds), given the lack of any scientific papers showing that typical gamma ray bursts will wipe out a planet's atmosphere, given the quick recovery time of a decade following ozone depletion by a gamma ray burst, and given only about a 20% chance of a particular gamma ray burst occurring over any particular planet's equator, we have no good basis for concluding that any substantial fraction of the universe's larger galaxies cannot evolve life because of gamma ray bursts. 

Trackback: http://arxiv.org/trackback/1409.2506 

The Best Way to Make One-Way Mars Colonization Work

Believe it or not, there is actually a web site on which you can sign up to become a Mars colonist. The web site is the Mars One website at http://www.mars-one.com. Looking at the front page, it's easy to be drawn in by the sales pitch. The site includes the following enticing slogans:

The whole world will watch and experience this journey. We are all explorers. Everyone, including you, can participate in space exploration. This can be your mission to Mars!

But there's one little detail they don't tell you about until you delve deep inside the web site. Those who qualify may get a ticket to Mars. But it's a one-way ticket. I did not see this fact clearly mentioned on the web site until I reached a “Technical Feasibility” page, where it mentions, “Absence of a return mission reduces the mission infrastructure radically.”

I think there is a huge potential problem with sending regular Earth residents to Mars on a one-way mission. The problem is that when they get to Mars, they may experience the ultimate case of “homesickness.”

Imagine you are a young man or woman who makes the long journey to Mars. At first, you are all flush with idealistic enthusiasm. When you first venture into space, you say to yourself something like this:

So this is it. Space – the final frontier! I have left Earth, the cradle of the mind, and ventured out into the vast ocean that is the cosmos. I am a modern day Odysseus. Next stop: the red planet Mars! What an intoxicating adventure!

But after you get to Mars, and settle into your little tiny space habitat, or your underground Mars cave, you start thinking more and more about the planet you have left behind forever. All of the things that you had on Earth (but took for granted) now become more and more precious-seeming to you. You remember being able to run through a field for as long as you want, feeling the sunlight on your skin, without wearing some spacesuit, and without always worrying that your oxygen supply will run out. You remember how great it was to sit on a beach and hear the waves and smell the fresh ocean air. You remember how wonderful it was to hike through a forest filled with a thousand types of life. You remember the smell of the pine trees as you walked through that forest. You remember the joy of plunging into the fresh water of a clear pond. You remember the fun of walking down the bustling streets of a city you had never visited before. And you realize that these and many other similar pleasures are all things you will never, ever be able to experience again.

Quickly, you grow sick of Mars, and think to yourself: get me the hell out of here. But there is no way for that to happen. You are stuck for the rest of your life in some place you no longer want to be, longing for the sensual pleasures of your birth planet.

We can only imagine what psychological ruin will come from such mental torments – possibly enough to cause the whole Mars mission to fail. Is there some way to avoid this?

One way would be to have a perfect virtual reality system – perhaps something like the holodeck system depicted on Star Trek: The Next Generation. Perhaps if there is some way for astronauts to be given a virtual reality system that makes it just like being on Earth, then astronauts who left Earth forever wouldn't get so homesick. But I doubt the technology for such a system will be ready in the time frame imagined by the Mars One project.

There is perhaps a better approach, which is to postpone a one-way Mars colonization mission until decades into the future. Before trying to colonize Mars, we could set up orbiting space colonies with hundreds or thousands of inhabitants, many of whom would be born in the colonies. Then the crew for a one-way Mars colonization mission would be made up of people who had been born in such colonies, and who had never lived on Earth.

Such space colonies could be rotated to produce artificial gravity by centrifugal force, a gravity that matches the lower gravity on Mars. From the time they were born in such orbiting space colonies, children could be conditioned to think of Earth as an unappealing place to live. 

  A poster at a future space colony (click to expand)

If inhabitants of such a space colony were to set off to Mars on a one-way colonization mission, they would not have the “homesickness for Earth” problem, because they would have never lived on Earth in the first place. People would not yearn and long to return to a place they had never been to in the first place. Such space colonists might actually be perfectly happy on Mars, which might give them more room to move around than they might have on their cramped little orbiting space colony.
 

The Croesus Chamber: A Science Fiction Story

Harold pressed a button on his desk, saying, “Send in the first person.” A man in a blue suit entered Harold's office.

“I have a sensational business deal to discuss with you,” said the man. “We have a very tasty new type of candy that will make billions for you. The only drawback is that one time in a thousand it will give a child a little bit of indigestion.”

“Why I would never be involved in something that might occasionally cause a child indigestion, no matter how many billions I made,” thundered Harold indignantly. “Get out of my office right now,” he demanded, pointing to the exit.

Harold pressed a button on his desk, saying, “Send in the next person.” A young woman entered.

“I came to you because you're one of the richest men in the world,” said the sobbing young woman. “The problem my family faces is the worst nightmare of every mother and father. But I thought to myself, if there's anyone in the world who can solve my ghastly problem, it's you.”

“Tell me all about it,” said Harold.

“My husband and I have had seven children,” explained the woman. “The doctors have told us that due to an extremely rare genetic defect shared by both me and my husband, all of our children will die before reaching the age of 15. Is there something you can do to help us?”

“There certainly is,” said Harold. “I am going to write a check for 50 million dollars. This will fund a team of the best doctors who will work night and day to solve your problem. I'm sure with a crash program funded by this check, a medical solution to your problem can be found.”

“Thank you so much!” said the woman, sobbing. “You're the most generous man in the world.”

Harold pressed a button on his desk, saying, “Send in the next person.” A middle-aged man entered.

“Tell me your name, and tell what I can do for you,” said Harold.

“My name is David Fallon,” said the man. “I'm sure you've heard about the hard times San Francisco has been experiencing for years. After the devastating earthquake, they never rebuilt the city properly. It's been a nightmare for the children. They don't have any proper schools to go to. They go to schools in ruined buildings, and as soon as they get out, the children go to beg on the street, or they go into gangs that steal money from adults.”

“I'm sure I can fix that,” said Harold. “I am going to write you a check for 500 million dollars. Use that to build the best schools money can buy. You should have a lot left over to fund some after-school programs.”

“You're an angel of mercy!” said the man, and he left.

Harold again pressed a button on his desk, saying, “Send in the next person.” A man with gray hair entered.

“What can I do for you?” asked Harold.

“I come seeking assistance for the people of Bangladesh,” said the man. “Ever since global warming got worse, and the sea levels started to rise, the life of the people in Bangladesh has been a watery hell. Every few months there's a flood that destroys their homes. Millions of them are starving and homeless. Is there anything you can do?”

“Why there certainly is,” said Harold. “I am going to write you a check right now for twenty billion dollars. I want you to use that money to relocate the entire population to higher ground. Make sure that nice dry houses are built for all of these people.”

“The gratitude of the people of Bangladesh is boundless,” said the man.

Yes, this is very satisfying, thought Harold. This makes me feel much better, he thought. But somewhere down inside himself he knew that it was all just an illusion.

None of his visitors really existed. He was in a room that could generate holographic illusions. He could sit on the chair behind the desk, and a computer could generate a series of visitors, who would look just like real people coming to meet him. Harold would write the checks, and give them to the holographic visitors, but he would not really be giving away any of his money.

Harold never really give away any of his money, one of the biggest fortunes in the world. He had become incredibly rich by doing what was right for his bank account, not what was morally right. He had started out investing heavily in cigarette companies. Then he started a company which sold self-driving cars. He made billions of dollars of profit when self-driving cars were very popular, before people realized that they caused a lot more fatal accidents than cars driven by people.

Then Harold started another company that created robot policemen. The robots put policemen out of work, and the robots didn't work right, meaning that many innocent civilians were shot by accident. But Harold made a fortune selling the robots, before people wised up as to how poorly they worked.

Then Harold invested in a biotech company that promised to turn back the clock, and reverse aging. Its product was bought by many millions, giving Harold billions of dollars in profits. Harold knew all along the product gave people cancer, but Harold sold all his shares before that fact became public.

Sometimes Harold would feel bad when he thought of all the suffering that his greed had caused. At times such as that, he would come to his holographic chamber, and press some buttons. Then a random series of computer-generated visitors would come, most of them asking for huge donations. Harold would write the checks, as if he was giving them whatever they wanted. Somewhere inside him, he knew it was an illusion and a charade, but nonetheless it always made Harold feel a little better, just as if he was someone with real moral feelings.

Homosexuality Hard to Explain Using Darwinian Orthodoxy

Under the thinking encouraged by many a modern materialist, almost everything about us can be explained by evolution and our genes. But there are difficulties in such thinking, one of which is properly accounting for the widespread existence of homosexuality.

Darwinism is centered around the idea that evolution slowly increases the prevalence of traits which tend to increase an organism's likelihood to survive until reproduction (and also the likelihood of the organism's reproduction). So suppose there were two genes in different organisms of a species, one which caused very strong sexual interest, and another which caused complete lack of sexual interest. According to conventional evolutionary theory, the first gene would cause more reproduction, which would cause the gene to become more and more common (all other things being equal), as the gene was inherited more and more often; but the second gene would cause less reproduction, which would cause the gene to become less and less common, because the gene would be inherited much less frequently.

How, then, can we account for homosexuality using such principles? Surveys indicate that between about 2% and 6% of the population are gay or bisexual. Given that very many gay people would never answer “Yes” when asked if they are gay, the actual percentage may be even higher.

Today homosexuality is generally believed to be an inherent tendency, not a choice; so under Darwinian conventions we have little choice but to assume that homosexuality has a strong genetic component. It has been estimated that homosexuals reproduce at only 20 percent of the rate that heterosexuals reproduce. It would seem that a straightforward calculation using Darwinian conventions lead us to the conclusion that homosexuality should have died out long ago. Whatever genetic basis might be behind homosexuality should have become less and less common, because of the vastly lower reproduction rate of homosexuals. It would seem, therefore, that homosexuality shouldn't exist, at least not in its current prevalence of perhaps 5% of the population.

Biologist J.B.S. Haldane imagined a case in which 99.9 percent of the population had one gene, and only .1 percent of the population had a second gene. If there was some reason why the second gene was 1% more likely to be inherited, then within 4000 generations, things would completely switch around so that 99.9 percent of the people would end up with the second gene, and only .1 percent would end up with the first gene. The example illustrates how strongly evolution tends to get rid of genes that are less likely to be passed on to descendants.

So how can we account for homosexuality under conventional Darwinian assumptions? Some theories have been suggested, but they haven't been very convincing. In this article evolutionary biologist David P. Barash discusses some possibilities for explaining this paradox, but he just doesn't seem to be able to get to first base.

Barash first mentions “kin selection” as a possibility, saying of homosexuals “perhaps they are able to help their relatives rear offspring, to the ultimate evolutionary benefit of any homosexuality-promoting genes present in those children.” That's very speculative, and Barash gives no evidence to support it, except mentioning some tiny Samoan gay group which he claims “lavish attention upon their nieces and nephews.”

Then Barash mentions a “social prestige” theory, claiming that gay men became priests or shamans, and that “perhaps the additional social prestige conveyed to their heterosexual relatives might give a reproductive boost to those relatives, and thereby to any shared genes carrying a predisposition toward homosexuality.” But Barash admits that this idea is “lacking in empirical support,” which means there is no evidence for it.

Another theory for the survival of homosexuality is that it had something to do with what is called group selection. As Barash puts it, “Although the great majority of biologists maintain that natural selection occurs at the level of individuals and their genes rather than groups, it is at least possible that human beings are an exception; that groups containing homosexuals might have done better than groups composed entirely of straights.” Judging from that wording, it doesn't sound like that theory is on solid ground, since it contradicts an assumption made by the “great majority” of biologists.

Barash also mentions a “balanced polymorphism” explanation, saying “the possibility cannot be excluded.” Again, not a solid speculation, since no evidence is provided. He also mentions the possibility of “sexually antagonistic selection,” but says there is “no evidence for this idea.”

So while Barash mentions quite a few possibilities, he gives the reader no confidence at all that evolutionary biologists have any good explanation for why homosexuality has not died out because of evolutionary factors. Barash has nothing but strained speculations, and the only evidence he claims to have is a thin and dubious claim involving some tiny group in the distant islands of Samoa – a country with a total population of only about 200,000.

It would therefore seem that the large-scale existence of homosexuality is a significant problem for Darwinian orthodoxy. In fact, as I explained in this essay, Darwinian orthodoxy has quite a few difficulties accounting for numerous aspects of humanity, such as our abilities for math, language, philosophy, introspection, and tendencies such as spirituality, aesthetic appreciation, and altruism, most of which don't do much good from a “survival of genes” evolutionary standpoint. It would seem that while Darwinian concepts are a valuable contribution that explain a great deal, Darwinism may be seriously oversold as some kind of “this explains everything” theory to account for human nature.

These are hard to explain using only Darwinism

Could any unorthodox thinking lead us to other possibilities that might account for homosexuality?

I know of one unorthodox hypothesis about the cause of homosexuality. The hypothesis goes like this: (1) some people alive on Earth have had previous earthly lives; (2) a male homosexual is typically someone who was previously reincarnated as a female; (3) that person is attracted to males because of a residual attraction to males carried over from a previous life as a female. The only evidence for this hypothesis is the evidence for reincarnation, which may be much stronger than many people think, due to the research of Ian Stevenson at the University of Virginia.

Another unorthodox hypothesis is the hypothesis that a large part of the blueprint or schema for a human being is stored outside of a person's DNA. I explained this idea in my previous post entitled “Half of the Blueprint for You May Be Stored Outside Your Cells,” in which I pointed out the curious fact that the species of plant known as rice is believed to have 38,000 genes, but humans (almost infinitely more complicated) are believed to have only 23,000 genes. In that post I summarized this idea as follows:

Genes are a very important determinant of human nature. But as they are merely recipes for making proteins, we cannot at all explain all the exquisite features of human nature by assuming that the secrets of human nature are all stored in merely 23,000 genes. There may well be some completely undiscovered information storehouse that also is crucial in determining human nature – an unknown noncellular “dark genome.” When a human body and a full human mind comes into existence, it may require information from cellular genes and this mysterious noncellular“dark genome.”

If there is some kind of “dark genome” that might help to explain human nature, homosexuality could be an aspect of that, perhaps some permutation of human nature stored among various other permutations in that “dark genome” (here “dark” simply means currently undiscovered). This “dark genome” or “second genome” might be unrelated to reproduction rates, so within such an information storehouse the continued existence of traits related to homosexuality might be plausible enough.

Another unorthodox idea, which no doubt will infuriate some fundamentalists, is that homosexuality has been deliberately included as part of the human mixture by a higher power, who wants homosexuality to exist so that it can one day be a significant brake on out-of-control overpopulation.

These ideas are admittedly speculative – but no more speculative than the totally speculative musings of Professor Barash, who seemed “lost at sea” when trying to give an orthodox Darwinian explanation for why homosexuality still is widespread.

Postscript: According to the book Dataclysm: Who We Are by Christian Rudder, a Google researcher has reported that 5 percent of porn searches are for gay porn, and that such a percentage is consistent from state to state in the US. This data tends to back up both the idea that homosexuality is inherent, rather than something largely chosen (given the local drawbacks of "choosing to be gay" in some US states such as North Dakota and Mississippi); and it also suggests a relatively high gay population (5% rather than just 2%). Such data tends to accentuate the explanatory problem mentioned in this post.