Monday, April 16, 2012


Impossible is a word that comes up a lot in my class, especially during discussions of physical or chemical properties. For example, electrons are often described as occupying a region (called an orbital) around an atom’s nucleus. However, these orbitals are only representations of the space where the electrons probably are. (Sort of like saying your child is probably at the mall; you can’t say exactly where, but you are pretty sure of the boundaries where they could be.) But that is not the true behavior of an electron. Electrons (like kids) don’t have to be in their orbital at all. They can be anywhere. It’s just very unlikely that they will be. In fact, it’s very, very, very, very, very, very, unlikely that they will be anywhere else other than their orbital, but it's not impossible. We say, there is a non-zero probability of finding the electron anywhere in the Universe.

The same rules apply to you. Since you are made of particles, and all your particles have a non-zero probability of being anywhere in the Universe, it is possible that you could instantly wind up on the other side of the Earth. For this to happen, all of your particles would have to simultaneously cash in their non-zero probabilities of being anywhere and simultaneously cash in their other non-zero probabilities for a new location. Unlikely, but technically not impossible.

When I mention this to my class, I am usually met with a healthy skepticism and general agreement that this will never happen. But there is always one student that insists on grabbing hold of the notion that it could happen. This is a seminal moment for those students. They are presented with a clear choice to either allow the meaning of words to be plastic; subtlety affected by the nuanced context in which they are used, or adhere to rigid definitions, unaltered by context. Impossible either is or it is not. It is not subject to interpretation.

I get it. But what does it mean to say that something is technically possible when it is practically impossible? Context matters. And in areas of extreme improbability, it matters most. It places reasonable limits in our pursuit of knowledge. We use the notion of technically possible but practically impossible to determine the cutoff for cause and effect. Did that new treatment really cure the disease or was it a fluke? What if I get the same result twice? Five times? What if the fluke only occurs 1 time in 20? In 100? Those individuals with the ability to shade meaning with context will thrive, while those that adhere to strictness will not. They will become curmudgeons, decrying every outcome as un-interpretable because there was a non-zero probability of another interpretation.

But isn’t this how science is supposed to work? Aren’t we lauded for pursuing new knowledge in the most unlikely of places, and criticized for snap judgments? Aren’t we supposed to be skeptical, ask for evidence, check and recheck, over and over again? Aren’t we expected to never say “never”?

The answer is a qualified “yes”. Scientific discourse does allow for the free pursuit of all ideas. It does allow for the open scrutiny of everyone by anyone. However, it does not allow for unfettered argument. There are rules of engagement. Contradictory points of view must build on current knowledge and be evidentiary. Alternative hypotheses must be able to withstand the glare of inquiry. The status of the author is irrelevant to the validity of the idea. It must stand alone. And not every idea will be permitted to participate in the scientific discussion. The ideas themselves must play by the rules. There are some that simply run afoul of expectation. They are not acceptable, dismissed outright, given no benefit of the doubt. Why? Because they are impossible. You are not allowed to claim you have created a perpetual motion machine or that you can travel faster than light. These (and others) are not permitted in our Universe. Arthur Eddington captured the limits to scientific acceptability in 1928 when he wrote, "But if your theory is found to be against the Second Law of Thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation.”

But what about ideas that are technically possible, however unlikely they may be? For example, what are we to do with a claim that another planet may harbor a civilization composed entirely of sentient DinosaursAre these ideas allowed to get in queue alongside others? Do we, in the interest of open-mindedness, commit any effort do disproving the hypothesis?

No. Ideas of extreme improbability break the rules. They are a distraction, unworthy of our attention. They are dismissed outright, on their own merits, for the simple reason that they are practically impossible. The probability of a Dino world is near zero, because the solution set of all possible organisms is near infinite, but there is only one organism that is a Dino. And that’s just here! The fact that this planet had dinosaurs is happenstance and irrelevant to the possibility of a Dino planet somewhere else. In much the same way that DouglasAdam’s sentient puddle wakes up to find itself in a hole that fits itself staggeringly well, we are biased towards making the impossible possible due to reflection upon our present circumstance. “We had Dinos, so there must be a Dino planet somewhere. It’s not impossible, right?”

This line of reasoning is related to the notion that if something can be imagined, it must exist in reality. Its origins date back to St. Anselm’s philosophical argument for the existence of that which can be imagined to exist. This argument was disproved almost as quickly as it was proposed, but remains latent in the population, only to recur during arguments of the impossible. “We can imagine a Dino planet, so it must be real. “ But, this philosophical fallacy notwithstanding, extraordinary claims require extraordinary evidence. And claims so extraordinary that they are practically impossible would require evidence equally impossible to obtain.

There is a non-zero probability of a Dino planet, somewhere. But since we already had a Dino planet, right here, I would check that one off the list. It’s not going to happen twice.

Copyright 2012 theBIOguy

No comments:

Post a Comment