It's always interesting when you find yourself contemplating a topic that involves a subject you've spent almost your entire life learning. These moments are made even more interesting if there is a gradual increase in thinking about the topic culminated by a large spike of interest and confusion. Now I don't want to talk about this actual process as it's probably the topic for another article.
Instead, this article is dedicated to such a moment I have found myself in very recently. The subject is life. The question is, what is it?
Now that's a question everyone has been trying to answer forever. But those conversations often involve some ridiculous metaphysical blabber that doesn't really offer an answer to anything (wink) and so my recent subject of contemplation is really not associated with such a vague questioning of life. The problem I'm having is much concentrated and perhaps less important.
Discussing this problem requires me to discuss how it became a problem. That is, the history that caused me to think about it. But I'm going to defer that until later and start right at what I think to be (at least right now) the main issue. So just take a moment and try to forget about everything before the next paragraph. The only point here is that some of the most seemingly obvious things require a second glance.
What separates life from non-life? Part of me agrees that it's a very easy question to answer. "Life" is a word with a scientific definition. Not only that, but there is an entire field of science dedicated to it. And this field's not small like quantum chromodynamics which is really just a small part of physics. This is fucking biology. It is the second largest pillar which holds up the natural sciences. So obviously there is something so distinct to life that requires it to have such a massive field of study dedicated to it. But maybe we should look at this definition of life a little closer.
Ahh, so you must be thinking, this is the age old debate of "are viruses living or not." Well, no. I have a long held opinion on that subject and it's not very interesting to discuss (they're not). I don't want to look at the definition of life to see what things it includes or excludes. I want to see what it implies.
But the virus debate does lead us to the first problem. Although life is a scientifically defined term, there are multiple definitions of it. A simple yet
unknown definition proposed for life is anything that functions on
negative entropy. I haven't studied entropy in a while and its actual definition eludes me right now (it's something like the total number of microstates something can take up and its mathematical calculation involves the Boltzmann constant). To make matters worse, I really don't even want to read up on it right now so I guess I'll just discuss it in very simple terms. Since entropy is often called "disorder" (though it's not nearly as simple as that), I would guess that the negative entropy definition of life would be anything that functions on creating order. After all, the human body is very complex and there is no way that it could be assembled without some serious work put into its development. But the negative entropy definition wouldn't just apply to creating order but also maintaining it. Again, our bodies need to be constantly maintained or else they would fall apart. In that sense, the negative entropy seems necessary enough to explain life. But you can probably see that it's a little vague. Therefore, we'll have to come back to it.
The more common (the one found in biology textbooks) gives a set of criteria rather than the broad generalization of "negative entropy." These criteria often vary but more or less involve the following. Life must:
a) Be comprised of one or more cells
b) Maintain a regular internal environment
c) Have a system of metabolism, that is, a system in which chemical energy is converted to energy used to either grow or maintain the internal environment
d) Be able to reproduce, either asexually or sexually (with same species)
e) Respond to external stimuli
f) Be able to evolve
Now, to me, there is something very odd about this list. And to address this oddity I must turn back to elaborate on the third paragraph of this article. The prime motivation for this post is questioning a fundamental belief that I've had for as long as I can remember. Is there truly something special about life? Again, the focus behind this question needs to be elaborated. I'm not talking about questioning our existence (though I'll touch on it briefly). Existentialism is close to what I'm driving at but it's still not the correct term. This topic does not single out humanity but rather life as a whole. To simplify, the intended use of the word
life in this article means the biological definition of life found above. It does
NOT mean life as in the "life we live."
Back to the actual matter, I've always had a belief that life
was something special. The difference between life and non-life was significant.
Life, the Universe, and Everything, the novel by Douglas Adams and part of his Hitchhiker's Guide to the Galaxy series, always struck me as a profound title. It highlights the two fundamentally separate aspects of our perceived reality and unites them with whatever else is out there. It would serve a perfect title for reality itself. To elaborate further, I posted an image in the last article with a bubble called "Natural Sciences." The natural sciences to me have always been founded on two pillars: Physics and Biology.*** But the more I think about it, the smaller the distinction between life and the rest of reality becomes. Reality should only be titled
The Universe and Everything. Physics is the one pillar holding up all of the natural sciences.
Why has my thinking changed? Well, that's a misleading question. The real question should be why I thought life was so significant in the first place. Perhaps I shouldn't have. When I look at the list, it only furthers the sentiment. This list is supposed to answer a very simple question. What is life? But let's change that question to make the dichotomy clearer. What separates, say, a bacterium from, say, a rock. A bacterium is a relatively simplistic organism and the first of its kind speciated very early in evolutionary history. A rock is a relatively simplistic formation created out of the dust and debris of a stellar collapse or formation and is present throughout the universe. Therefore, the comparison is apt. We're talking about some of the (but not
the, as that could definitely be the subject of a new post) fundamental constituents of life and non-life, respectively.
Back to the topic at hand, my problem is not that the list is inadequate in describing the differences between a rock and a bacterium, but that it is
too adequate. There is no magic or mystery behind the distinction. If life were some truly significant and unique thing in the universe, as I once believed, there would be
no way to describe the differences between life and non-life. At least, not without invoking metaphysics (for example, the idea that life has a "soul"). But no, we have deciphered the difference and described it in terms of physical processes. But why is this so surprising? All current theories of abiogenesis are only concerned with physical processes and I've known this ever since I took my first biology class in sixth grade. The surprise is the realization that the difference between a rock and a bacterium is no more significant than the difference between a rock and water.
But we're not even done there. The list of criteria for life does not even seem unique to life. For instance, let's remove the first criterion as "life being comprised of cells" seems like a statement made out of regional bias. If we observed a bacteria-like creature in some far away galaxy that was technically not composed of what is defined as a cell on earth, would we not hesitate to call it a life-form? (I know this is hard to grasp since a bacterium
is a cell, but cells, in a looser sense, are merely houses for DNA to live in. Therefore, this extra-terrestrial bacterium would merely be something that behaves exactly like an earth bacterium but whose behavior is determined not by DNA but some other, foreign genetic material. If this is still not satisfying, I will discuss the significance of DNA towards the end of this article.) After removing the cell-criterion, I can't help but realize that the rest of the list is eerily similar to the bright white objects in the nighttime sky and the brighter yellow object in the daytime sky. Of course, I am talking about stars. And after giving it a lot of thought, they're a lot closer to everyday life than I would have ever imagined.
Stars maintain their internal environment. A star has to produce energy by fusion in its core by definition. This
is the star's internal environment (though there are several other parts making up a star that I won't mention since this article is too long as is). If the fusion is not maintained, the star will either expand or collapse, both resulting in its eventual death (which only furthers its similarities with life). This internal environment is maintained through the star's metabolism. Chemical energy (the protons colliding in the star's core) are converted to energy (through E = mc^2) in order to maintain the pressure balance between the inside and outside of the star so that it doesn't collapse due to gravity. Addressing the criterion of reproduction is trickier but still possible. In order to do it, we must look at the current theoretical models of stellar evolution (yet another similarity with life!). These current models show, that when a star dies, whether it's through expansion or collapse, its material is shed out into empty space. This material is then used to create a new star. It is not hard to see the parallel with reproduction on earth. The star spews out its "genetic material" which is used with the genetic material from other stars to create a new life, born with the properties of its parents. Stars also respond to external stimuli. After all, what are external stimuli besides the forces of nature, which stars have to deal with constantly. While they might not show the reflexes of a human when hit, they are certainly no less responsive to their environment than the simplest organisms on earth. Lastly we have the criterion of evolving. This is easily seen once again by looking at the reproduction example. Since new stars arise from old ones, they also evolve. Some stars die in violent explosions called supernovae. These supernovae are so energetic that they are able to create heavier elements through fusion. Whereas elements like hydrogen, helium, and lithium were produced soon after the big bang and before stars were formed. But every element after that**** was produced from the energetic supernovae of high mass stars. Therefore, stars have evolved because the abundances of heavier elements in the universe has increased. Stars being created now have a greater abundance of heavier elements than their parents, on average.
Ok, ok, stars are a lot like organisms. Why is that so important. Well, it's important for several reasons. I think just the fact that they share so many similarities with the strict definition of life is interesting in itself. Perhaps our definition of life is too strict. Why does life need to be made up of cells? The difference between a rock and a bacterium is certainly not much if at all greater than the difference between a rock and a star. This is disheartening at the same time. Our traditional definition of life seems even less significant now. How can bacteria and mushrooms and trees and goldfish be so distinct from the rest of the universe when they hardly have a minuscule fraction one percent of the impact that stars do on the universe. Stars burn for billions of years, control all matter within a billion miles, and produce more energy in one second than humans can even dream about. Moreover, there are more stars are a ubiquitous feature of the universe. They are found everywhere. If life is constrained to a tiny, pale, blue dot in the cosmos, how can it be a significant part of the universe at all?
And then there's the fact that life would not be possible without stars. The sun is the primary source of energy. It is required for the food chain to even exist (whereas primary producers such as plants are only required for the food chain to grow). If that's not enough, I mentioned earlier that stars are responsible for creating elements heavier than lithium. Since DNA itself contains elements such as carbon, nitrogen, and phosphorus, life would not even have had the ability to form without stars. As the famous saying goes, we are essentially stardust. Except "we" pertains to all life as we know it.
If you don't share my concerns about the connotation of life, let's do a quick recap. Basically what we've learned is that there's not much of a difference between a rock and a bacterium, which translates into a small difference between life and non-life. Then, any difference there was between a rock and bacterium is magnified tenfold in the difference between a rock and a star. If that's not enough, we've also learned that stars are way more significant in the grand scheme of the universe and are responsible for the origin of life in a tiny tiny tiny tiny part of the universe.
But in all this modesty about life, there lies a way out to show that life truly is something special. The reason once again goes back to stars. While they are responsible for the creation of life, we don't know why stars formed. Sure, we know
how they formed. They formed from a collapse of swirling hot gas. But we don't know
why they formed. Calculations show that slight differences in fundamental properties such as the charge of an electron or the strength of the gravitational force would produce a universe that is dramatically difference than the one we are in. Since we don't know why these fundamental properties exist, we therefore do not know why things are the way the are.
But one can see an obvious reason for why things are the way they are. For why the charge of an electron is -1.6 * 10^-19 coulombs and the strength of the gravitational force is inversely proportional to the square of the distance between two objects. The answer is that such conditions are necessary for the creation of life. Assigning a purpose to the universe may seem a little naive, especially when the purpose is the origin of life. This clearly shows the bias we have as humans (or organisms) and runs counter to everything discussed the last several paragraphs. But the reasoning may not be so far-fetched.
Let's go back to the other definition of life that was mentioned earlier, the so called "negative entropy." As I've said before, I don't know much about the quantum definition of entropy but I do know some of its implications. The one I want to talk about now is that it's the only physical law that's time asymmetric. The second law of thermodynamics is that entropy always increases. A hidden aspect of this law is the direction of time. The law assumes that time always goes forward and so entropy always increases with time. Therefore, another way of phrasing the statement is that entropy increases with time. This is time asymmetric because, while it can be said that entropy also increases in the past, we know that it does not. We open a can full of air and the air spreads throughout the room. Entropy can't increase in the past because we know the air was highly ordered in the can in the past. If entropy increased in the past, we wouldn't even be able to trust our memories, which would result in a universe that's far too complicated to even bother writing about. But any other law does not share the time asymmetry of entropy. Newton's laws show that just as the air molecules spread out into the room, they are just as likely to come together and go back into the can. Even the Einsteinian updating of these laws shares this similarity. The point is, that if entropy
always increases with time, how is it possible for something with negative entropy to even be created? Conditions would have to be just right for this to occur, and this is no probability. While I don't know the exact numbers of the calculation (and don't even know how to do the calculation itself), I'm confident that the law of entropy makes the probability of the creation of life, let alone one of the most complicated objects in the universe*****, much less than the probability of me winning ever lottery ever held for the rest of my life.******
So could it be that stars, while burning for an eternity are controlling anything in their vicinity, are merely serving a purpose to create life? Could it be that stars are under the full control of life, existing solely to create it and further its development and evolution? I think it's certainly an interesting idea and maybe even a possibility, and
I'm not the only one that thinks so. So we went from life and non-life to being to fundamental constituents of the universe, to life completely losing its significance, to the idea that the universe only exists so that life exists. The pillar of biology is erected once again and is responsible for the building of the physics pillar as well. And that's the shocking twist I know you've all been waiting for.
But while this anthropic principle has many implications, I want to talk about what it doesn't mean. Another aspect of the list that I didn't mention was that humans get no special treatment. The list makes no mention of thought, emotion, art, language, and anything else we associate with distinctly human life. When it comes to life, these things are mere byproducts of a strict evolutionary pathway, not much different than oxygen, water, and glucose formed as the byproducts of photosynthesis. So, while stars and other members of the universe are under the full control of life,
so are we. How is this possible when we
are life? Well, we must go back to the first criterion of life that we omitted earlier: cells. But as I said in the parenthetical note, cells are merely houses for the true constituent of life to live in: DNA. The thing that maintains the internal environment of an organism, regulates its metabolism, drives it to reproduce, and cause it to evolve are not the organism itself but its DNA. Therefore, the purpose of the universe is not to create intelligent life that can make some really good music and movies and tv shows but to create and propagate DNA. And
that is the truly remarkable twist. The tiny, coiled up double helix is pulling all the strings (
hmm...) of reality.
Now it's time to discuss some things that are relevant to this recent realization but not all that relevant to the article as a whole. However, the discussion here is to small to fill up an entire other article and I'm afraid I might lose my current train of thought if I postpone writing this. I've become a believer in the idea that our DNA controls us rather than the other way around. Everything that we humans as a species do is a mandate from our DNA. So while some philosophies try to ascribe metaphysical qualities ("souls") to humans that make them fundamentally different from not just non-life but also "lower" life-forms, I believe that humans are firmly operating within nature's physical laws and constraints. However, this does not mean that humans are not significantly different from other organisms. Unlike other life-forms, humans have manifested themselves in a holy trinity, with each piece having its own goals. The first piece is the one mentioned earlier: the species. The human species is fully under the control of DNA and its only goal is to maintain the survival of itself (or more specifically the survival of its DNA). The second part is the individual, whose goal may or may not be survival (I haven't really decided how I feel about this yet). However, the individual also has a secondary goal which is to achieve happiness (or rather, defer unhappiness). This is a little hard to be objective about, but another way to put it is to maximize pleasure (or rather, minimize pain. So far, these two pieces of the holy trinity are not unique to humans. Each species has individuals that make up the species, with the two sometimes having conflicting goals. But the third aspect of humanity is society, which has a goal that combines those of the species and the individual. This goal is progress and exploration, as they both contribute to the survival of the species and the the overall happiness of individuals. Since this aspect is unique to humans, I believe that humanity's drive towards progress and exploration are its truly unique aspects.
But this is my no means a sophisticated analysis of nature and society but rather just the ramblings I feel like expressing every now and then. However, I think a fundamental question to ask oneself is to go back to the difference question. Given the following choices, rank each from what you think has the greatest difference between the two to the least.
1) rock and bacterium
2) bacterium and any organism with a brain
3) any organism with a brain and a chimpanzee (or, if you like, a now extinct ancestor of humanity)
4) the latter choice in "3", and a human
I used to think that the list was 4>2>3>1 but lately I'm becoming more and more a fan of 1>2>3>4.
***For those of you wondering, "WHERE IS CHEMISTRY???????????" the omission is due to the fact that I now believe chemistry acts as a bridge between biology and physics. Other sciences are either irrelevant in the pillar due to regional bias (geology, earth science) or are constituents within the larger pillar (astronomy belonging to physics). Please note that sciences like geology and earth science are not meaningful. They are just not pillars because of regional bias, just like I thought biology should be removed because of a regional bias. This does imply something silly like we should have stopped teaching biology.
****Of course, the the bottom part of the periodic table (and not just the actinides) is made up of elements that have been synthesized by man, not by stars. However, this means that these elements are not naturally occurring because they immediately decay radioactively after they are formed. I am unsure as to if an element like darmstadtium is able to be produced by a star, even if it's for a fraction of a second.
*****The human brain.
******I realize this argument about entropy is flawed. First, if the anthropic principle is true, then entropy is part of the necessary conditions for life. Therefore, any arguments about probability are useless since entropy is in place to make the probability that life arises equal to exactly 1 (which, as far as we know, it is). Second, entropy makes it entirely possible for complex systems to arise at the expense of energy expenditure. While life is incredibly complex and functioning on so-called negative entropy, there is still an overall increase in entropy because of the energy it must expend. Therefore, life may have arisen for the exact opposite reason of the anthropic principle, meaning that conditions of the universe just so happened to create life the way it is because it's the only way it could have. If the universe had other properties, who's to say that life wouldn't still exist, albeit in a drastically different way. Nonetheless, my reasoning has more to do with the hard to believe fact that something so complex like life has been created for seemingly no reason.