Anthropic means 'having to do with human beings' (intelligent life) - so the anthropic argument is speculating about the universe's setup for human life. First introduced to the scientific community by Brandon Carter in 1973 [1], the anthropic argument was intended to clarify the work of Copernicus (who believed mankind was not in a "privileged" position in the universe). Carter believed that although mankind may not be in the center of the universe, it was impossible for us to be in the universe if we were unable to witness it. In essence, the universe could not be "observed" if not made to include observers. If it was created in any way that deviates from what we observe, not only would human life be unable to exist, but there would be no life to observe the universe.Worded formally, this is known as the "weak" anthropic argument, distinguishing it from the "strong" argument (also later developed by Carter). The latter is "strong" in that asserts a much bolder (but simplified) position - the Universe had to bring humanity into being.
To better understand the gist of these arguments (for interests of time I will not delve into the minute differences of weak and strong principles), think about other planets in our solar system. Beyond speculations of Kepler exoplanets, the planets were know of are completely uninhabitable. Temperatures are too extreme for anything to survive - the planets are vast wastelands. If any of these planets represented the entire universe instead, the universe would essentially be a wasteland as well. No human or animal would be around to acknowledge this. The universe itself, then, may as well be non-existent. The fact that we are here to know all this says something about WHY.
The strong argument is so bold as to be controversial by any look, and thus it will not be addressed here. Our focus will be on the weak anthropic principle. This will prove difficult, as the argument was derived by someone with no intention of evaluating the universe's origins. As we saw with the teleological argument, however, a universe as ordered and structured as ours must have some similarly ordered (purposeful) cause. In our case, this would be God. As with other arguments we've evaluated, random chance is the only alternative, as it merely appears to have order, but in fact is chaotic and senseless.
With that said, a traditional objection to acknowledging an intelligent designer behind the earth's fine-tuning would look like this:
Only a universe containing intelligent life will have observers, so there is nothing special about our universe. It is necessary for it to be finely tuned. If enough universes exist without intelligent life, it is only by chance ours is the only one we are aware of and able to observe.In short, if a large enough number of universes could exist, it is no surprise one would, by chance, be produced with all the right constants for life. This objection eludes to the so-called "multiverse" (existence of multiple universes) needed for it to be a valid argument. This "multiverse" - a virtual hypothetical in physics - exists only by convention. It is the only way to explain how the improbable odds of "random chance" creating the order we see, could be possible. If there are enough universes, the odds are better.
This is why scientists sometimes embrace the anthropic principle - to them it confirms why our universe is observable, but other possible universes (which increase the "chance" of our universe's occurence) are not. In response, however, this clearly is rooted in more physical evidence than it would be said I have for God's existence. I also offer this - could God not have created a multiverse? (not that I necessarily believe this)? Also, supposing it exists, why should the multiverse even allow the creation of intelligent life? [2] We assume intelligent life is needed for observation, but why should it exist amongst the supposed array of chaotic, random, lifeless universes?
If intelligent life is not really needed in a multiverse, then we can say the existence of intelligent life perhaps begs for a "purposeful" cause - God. Inn some ways, the abstract concept of the "multiverse" is little different from arguing "God did it". It makes sense of things without itself being a visible, physical reality. But let's be clear - both cases avoid evidence, yet only in 1 explanation makes sense of why life should even be expected to exist. In a time when Christians (and any believer in God) are said to ignore science or evidence, or hold belief without evidence (a topic I will explore following this series) - this is worth pointing out. The odds are stacked against "random chance", no matter how many universes might exist or might make the explanation more likely.
On the other end of hypotheticals for the anthropic principle, there are numerous proofs in the way of logic, probability and Bayesian formulas. These are hotly debated, and not in my area of expertise so I will skip this aspect of the debate. I trust what I cover here is sufficient to help one make up their mind. Much like the cosmological argument, though, how one defines their terms will always be a subject of debate. Criticism in this area only helps us refine and clarify our position. Offering it as an "end all" proof is questionable.
Moving away from the hypothetical, let's get more into reality. I want to look at just a handful of evidences, or "constants" in our universe's operation, that indicate it may be "finely-tuned" for intelligent life.[3] These are, after all, the amazing observations that triggered awe for the scientists developing the anthropic argument.
- If surface gravity was stronger, the planet’s atmosphere would retain huge amounts of ammonia and methane. If it were any weaker, the atmosphere would lose too much water
- The 23-degree axis tilt, if it were altered slightly, would cause temperatures on Earth to be too extreme
- If there were more less seismic activity (earthquakes), nutrients on the ocean floors and in river runoff would not be cycled back to the continents through tectonic uplift.
- If we were too far from our parent star (the sun), we would be too cool for a stable water cycle. If we were too close, it would be too warm.
- If the "weak nuclear force" were slightly stronger, the universe would consist completely of hydrogen. If it was any weaker, the universe would be 100% helium.
- If Jupiter was not in its current orbit, we would be bombarded with space material. Jupiter’s
gravitational field acts as a cosmic vacuum cleaner, attracting asteroids and comets that would
otherwise strike earth.
To look at this another way, scientists use this analogy: suppose you are tied to a post and facing a firing squad. Everyone in the squad aims their gun and fires. To your surprise, after hearing the gunshots go off and seeing smoke rise, you find you are still alive. You have survived. The reasoning above - that we are here simply because the universe developed the way it did - is the same as saying "Of course I survived the shooting. Everyone else missed their shot!" True as this is, it does nothing to answer the more obvious question - why did everyone miss? If even 1 person had hit, things would have ended very different for you - you would not have survived. Speculation about what kind of person could have survived the gunshot is much less relevant.
Let's take a closer look at this thinking. First, given that all forms of life we know are carbon-based, I would question why we should expect life to exist in another form. Going back to the Big Bang, proponents of the anthropic principle point out if anything happened differently during this crucial event, the universe may have been too unstable for anything to exist. So why speculate about other types of lifeforms that may have developed differently? We may be lucky to be here (or privileged, if you believe God has put us here) - but someone needs to prove it is reasonable to expect other life to exist AT ALL. And, even if that were shown, that fails to rule out God as a creator. It merely means he would have had to create us with a very different composition. Whether or not the universe is efficient without His involvement is of little consequence to whether or not it was put in place by Him to start with. This expresses the importance of differentiating between efficient causes and final causes. Showing that the universe is efficient, regardless of how it is done, does not address whether or not it had a final, purposed cause.
The last objection I've seen to the anthropic principle is a more recent one in the news. It is often said if the universe is so "fine-tuned for life, then Einstein's cosmological constant (which is a determination of how fast or slow the universe is expanding) would be expected to have a value that maximizes the creation of life. But as recent research from Canada reveals, the actual value in our universe is slightly positive. According to Don Page, this means it "dilutes matter and prevents a lot of gravitational collapse making our universe less likely for life than if the constant were not positive" [4].
Unfortunately, like assuming God does not create chaos, this argument assumes God must create a universe with the absolute best possible cosmological constant for life. To do otherwise, I suppose the thinking goes, would make him less benevolent or "pro-life". This means that God must fit the scientist's tightly constrained box in order to be plausible whatsoever. But that merely begs questions. First, is God really less "good" because our universe is not as efficient as it should be? What if being "good" or "perfect" involves balancing chaos with purpose, rather than eliminating it all together? (this is intimately related to the infamous "problem of evil"). Second, as creationists might point out, we assume the constant has, in fact, remained constant. But what if our universe is not efficient now because a change was introduced at some point in the (unobservable) past? For instance, God's curse on creation after Adam/Eve's disobedience?
Ultimately, the anthropic argument is one that will always be interpreted based on what you assume to be true about the universe's origins. It can not point someone specifically to God, as it is more a compliment to the teleological argument and subject to similar limitations. But it can remind those of us who believe in God that this world is not one of many random universes or worlds. And it can remind those who do not believe in God that we have many reasons to be thankful for our lives everyday. Whether or not you believe the universe is cooling, expanding, heating up, dying out or being renewed - it is a masterful work of art that functions efficiently. One particular anthropic constant may be co-incidence, but dozens of them being just right for anything in this universe to remain stable - that begs for acknowledging something greater than ourselves. If you think that random chance really makes more sense than intelligent design and purpose, I would hate to see how unpredictable your outlook on life must be.
[1] What Is the Anthropic Principle?" WiseGEEK: Clear Answers for Common Questions. Web. 17 Jan. 2012. <http://www.wisegeek.com/what-is-the-anthropic-principle.htm>
http://en.wikipedia.org/wiki/Anthropic_principle
[2] Castellano, Daniel J. "A Critique of the Anthropic Principle." Repository of Arcane Knowledge - Home. 2006. Web. 25 Jan. 2012. <http://www.arcaneknowledge.org/science/anthropic.htm>.
[3] Barrow, John D., and Frank J. Tipler. The Anthropic Cosmological Principle. Oxford [Oxfordshire: Oxford UP, 1986. Print.
[4] Page, Don. "Evidence Against The Universe Being Fine Tuned For Life." The Eternal Universe. Web. 27 Jan. 2012. <http://www.theeternaluniverse.com/2011/01/evidence-against-universe-being-fine.html>.
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