Wednesday, January 29, 2014

D is the new F

The Myth of Raising Standards through Minimum Grades 

There is a trend at America’s colleges and universities to raise standards by instituting minimum grades.

Typically the minimum grade is a C-. It may be in the form of a prerequisite: You may not take BIOCHEM 202 unless you have completed BIOCHEM 201 with a grade of C- or better. Or it may be in the form of program requirements: You must achieve a grade of C- or better in all courses required by the major.

This is not raising standards. It is creating grade inflation and grade compression.

Imagine you are teaching physics to a senior biology major. Imagine the student is in the second semester of his senior year. (Biology students often delay taking a physics until the last possible moment!) Now imagine the student needs a C- to graduate. When you compute your grades you find that this student earned a D+. What do you do? Do you give a biology student a D+ in a physics course, preventing graduation?

Well, what you are likely to do is to give a C- because—you simply don’t want to prevent a student from graduating because of the minor difference between a D+ and a C-.

 I have seen grade distributions that confirm this. Distributions that demonstrate that professors show a great reluctance to give D’s if the student needs a C-. That’s grade inflation (giving higher grades than deserved) and grade compression (C- now incorporates earned C-’s and D’s—patently unfair to the true C- student.)

Employers know what a D means (or used to mean.) They can no longer be confident what a C- on a transcript means.

This is all based on apple pie “raise the standards” nonsense. In my view, if a student completes BIOCHEM 201 and is not ready for BIOCHEM 202, the student should fail 201. A D has historically meant a passing grade. It includes the message: you passed, barely, and if you don’t work harder we are not optimistic that you can do well in 202, but we are going to let you try. Because, well, you did pass. Likewise if you fail to master the content of a course required for a major then you should fail the course. If you get a D then you pass, and let the D stand on the transcript.

In the twisted universe of minimum grades, there is no difference between a D and an F. They are equivalent failing grades. The D is the new F.

Monday, January 20, 2014

Coyne's Bad Logic Bowl XLVIII

Jerry Coyne is all excited over the fact that an account that predates the Jewish writing of the Noahic flood has striking similarities. On his site he writes:
We’ve known since at least 1872 that the Great Flood detailed in Genesis is a descendant of earlier flood myths from Mesopotamia. And there may be some credibility to the presence of at least some serious floods then, based on the fact that Mesopotamia is a giant flood plain and the presence of some archeological evidence for a big flood around 5000 BC. But what we didn’t know until now is that those earlier flood myths also incorporated a boat onto which species of wild animals were sequestered to save them—two by two! This clearly shows, as if we didn’t know it already, that the Genesis story of Noah and the Ark isn’t true, but was simply an embroidery of earlier flood stories.
Coyne's logic is so bad one wonders why he is allowed to teach.

We are only discussing the logic--not the truth of any sort of flood. Coyne's logic is wrong--very wrong, regardless of whether or not the flood is global, local or a total fabrication. His logic is so bad that I would consider it embarrassing if we were on the same side.

It is trivial to understand how wrong he is. Imagine:

  • 5000 years ago there is some cataclysmic event. Maybe it's a flood. Or a volcano. Or an earthquake. 
  • A description of the event is passed from generation to generation, starting with the survivors, and originally confined to the area of the event. 
  • Eventually the people split into different groups or tribes. Their stories begin to diverge. Not totally--but they are distinguishable. 
  • 3000 years later group A writes down its version of the ancient event. 
  • 500 years later group B writes down its version--which has similarities. 

Coyne's faulty logic is that the similarities between A and B combined with the later date for B means we now know (Coyne likes to say we know things--he is almost always incorrect in how he uses that word) that B's account isn't true.

It may be that B's account is not true. But we don't know that. The two groups may be describing the same actual event (or the same ancient myth.) Furthermore, it may be that people B did a better job at preserving the story from generation to generation.

We don't know that B's account is not true. And Coyne doesn't know it. What we do know is that Coyne has a serious problem with basic critical thinking.

Monday, January 13, 2014

Science Denialism: Pot. Kettle. Black.

On atheist blogs you generally see a strong and not unwarranted attack on climate-change deniers, especially those who “don’t believe” in any significant anthropogenic contribution to global warming. 1

The general criticism (of the deniers) has four common planks:

1.     The climate-change deniers, though typically not scientists themselves, show utter disregard for the scientific consensus.

2.     The climate-change deniers are ideologically motivated, by politics, economics or both.

3.     The “science” of the climate-change deniers often is not science at all, but trivial and anecdotal. (Gee it’s cold out, I could sure use a bit of that global warming! Ha ha!)

4.     The references provided by climate-change deniers, if any, are often not to scholarly peer-reviewed literature but to unpublished work of fringe scientists or popularizations.

I have seen, for years actually, the exact same pattern of science denialism, often by those making the charges against climate change deniers.

They are fine-tuning deniers.

Let me give my definition of fine-tuning.

Fine-tuning: It is the observation that the ability of the universe to synthesize heavy elements (heavy = anything beyond Helium, or “metals” to Astronomers), which are necessary for any kind of life, appears to be sensitive, extremely so in some cases, to the values of various physical constants. This sensitivity is across the board: first in the fact that there are any stars at all, then to the range of lifetimes of the stars, then to the process by which stars synthesize heavy elements, and finally to process by which some stars end their lives (by exploding) and thereby seed the universe with those elements.

Here are some facts about fine-tuning:

·      It has nothing to do with probability. It has to do with sensitivity. There is nothing in the definition that relies on any assumption of the a priori probability of the constants. They could be random draws (extremely low probability) or unit probability (from some unknown theory of everything). It only matters that the creation of the elements necessary for life is sensitive to the values.

·      It is a consensus viewpoint, especially among “in-field” scientific disciplines, such as cosmology, astronomy, particle and nuclear physics.

·      It has nothing to do, per se, with religion or “intelligent design”. Sure, it has been co-opted by some, and very stupidly by the ID crowd 2 who, without reason (and ultimately to their disadvantage) hitched their wagon to a “low-probability therefore god” argument. But ideas can always be co-opted 3, such as evolution and genetics being co-opted for eugenics. You have to evaluate the scientific idea on its scientific merits, not on its potential for use by people you don’t like.

·      It is considered a serious scientific problem/puzzle (and therefore quite interesting) by scientists of all religious stripes. Some of them quite famous for their atheism as well as their science, such as Weinberg, Susskind, Krauss, Smolin, etc.

The fine-tuning problem is even a very real part of the motivation for a push toward a multiverse theory of one form or another. It is appealing to solve the problem by confirming there are many (essentially infinite) universes with different constants, and only those (such as ours) with a fortuitous draw have intelligent life pondering their good fortune. 4

This is the state of affairs. It is irrefutable that many scientists, many of them famous atheist scientists, view the appearance of fine-tuning as a serious problem, one that should not be summarily dismissed because of a perceived ideological inconvenience. No, it is a problem that is screaming for a scientific solution.

Yet If you try to make this point on atheist blogs (I have tried countless times) some of the same people who legitimately attack climate-change denialism will use the same methods in their fine-tuning denialism.

1.     They will disregard the scientific consensus. It suddenly won’t matter that a majority of in-field scientists think fine-tuning is a serious problem. In fact, pointing out that many scientists think so will often be “refuted” by charges that one is “arguing from authority.” But pointing out that most in-field scientists acknowledge global warming and pointing out that most in-field scientists acknowledge the fine-tuning problem is not an irrational appeal to authority.

2.     Like climate-change deniers, many of the fine-tuning deniers appear to be motivated not by science, but by ideology. The reasoning, sometimes behind the scenes and sometimes front and center, is “fine-tuning→intelligent designreligionbadtherefore it must be wrong (at all costs).  It connects the evaluation of science (the reality of the fine-tuning problem) with something not scientific (it gives the “bad guys” an advantage)—and that reasoning is always wrong.

3.     Most frustrating to me is that the “rebuttal” of fine-tuning is often trivial. I cannot count how many times someone has given me, in gotcha tones, the Douglas Adams puddle argument, which has no application whatsoever to the cosmic fine-tuning problem. 5 Another kind of trivial response is the “how do we know there couldn’t be life with only hydrogen and helium?” rebuttal.  This ignores the fact that you can’t make anything out of those elements, and that any life, using a non-controversial assertion, needs large molecules to store information. And, by the way, the (effectively) “I saw a creature on Star-Trek who was made of pure energy so who knows?” Stated with an assumption of moral superiority overs us matter chauvinists, is not a scientific response. Another trivial dismissal of the fine-tuning problem is to project one’s own disinterest onto the human population at large. This is the “I just don’t see it as a big deal, we are here and that’s that, just move on” argument. This implies that scientists should just shut up and listen and not consider “how is it that we are here?” to be a question of interest. Finally, some will irrationally attack it because of its name. But “fine-tuning” does not imply a tuner—it’s used a metaphor. Get over it.

4.     The fine-tuning deniers have their authorities that they believe should end the argument. First and foremost is Victor Stenger. Because Stenger (who, to be fair, has a good idea, to show that the fine-tuning is an illusion) has published a popularization—well that settles it, doesn’t it? But the fact is that Stenger, in attempting to show fine-tuning is an illusion, has only done sloppy work, he has not published in peer-reviewed journals, and you do not find those scientists who consider fine-tuning a serious problem (like the atheists I mentioned) now saying: “OMG, we were worried about nothing! Stenger solved it for us!” Because Stenger did nothing more than a few back-of-the-envelope calculations and then wrote a popularization in which he claims to have solved a serious problem. He didn’t. He has a good idea that he has not run with scientifically—he has, instead, marketed it adroitly. (For a competent takedown of Victor Stenger, read Luke Barnes.)

As an example of someone who is willing to look stupid to deny science just because it bothers him ideologically, consider P. Z. Myers. He was aflutter over a piece in the New York Times that was concerned, in part, with fine-tuning. (And its close cousin, the weak Anthropic Principle, which is essentially what the multiverse proponents, in lieu of any experimental data, are invoking to explain the fine-tuning.) Myers wrote:
Alas, Davies also brings up the anthropic principle, that tiresome exercise in metaphysical masturbation that always flounders somewhere in the repellent ditch between narcissism and solipsism. When someone says that life would not exist if the laws of physics were just a little bit different, I have to wonder…how do they know? Just as there are many different combinations of amino acids that can make any particular enzyme, why can't there be many different combinations of physical laws that can yield life? 
Which shows complete ignorance of the subject he attempts (with an epic FAIL) to criticize. He doesn't seem to grasp that if the constants are tweaked a bit there will be no elements to produce amino acids or any other molecules necessary for any kind of life.

Why is P.Z. so dumb? Because he can't grasp that fine-tuning is a metaphor. He is a afraid that it gives to much ammunition to the theists.

He reveals this when he doubles down on his stupidity:
I'm also always a bit disappointed with the statements of anthropic principle proponents for another reason. If these are the best and only laws that can give rise to intelligent life in the universe, why do they do such a lousy job of it?
Forgetting that, again, it's a metaphor, he is essentially making the irrelevant value statement that: if there is a fine-tuner, why then he is an incompetent dolt. We can ignore that criticism (which is metaphysics, not physics) and point out the obvious. The fine-tuning problem in no way, shape or form says that we are in the best possible universe for intelligent life. It says only that the habitability of our universe is sensitive to the constants,

To summarize I think that, on blogs at least, there is a massive case of Pot. Kettle. Black. when it comes to science denialism. You can find many commentators bashing climate-change deniers out of one side of the mouth while from the other side they spout the same denialist unscientific tricks when it comes to the cosmic fine-tuning problem.

1 My own position on climate change is this: I am a nuclear physicist. I have no expertise in the field of climate change. So just like any other scientific argument that is out of my field, and for which I have no time or interest to ramp up, I accept the scientific consensus.  I have confidence that the checks and balances inherent in science mean that, when you don’t know and can’t evaluate on your own, it’s a good bet to accept the consensus view of in-field scientists. Or stay quiet.

2 From a strategic viewpoint (and from a theological one) the ID crowd is wrong to adopt a “low-probability implies god” position. A low probability universe is exactly what the scientific community argues is to be expected in the multiverse.  Any multiverse theory is perfectly happy to acknowledge that our universe is mind-boggling in its rarity.  On the other hand, a “theory of everything” with no free parameters (which isn’t going to happen, but let’s pretend) would be on the other end of the probability spectrum (the constants would have unit probability) and, coupled with sensitivity to those constants (fine-tuning) would make the best prima facie case for a designer. It would mean that habitability was built into the fabric of space-time. Short of God making a personal appearance, there is no better result that theists could wish for. It always surprises me that the IDers do not see this.

3 I find it useful to point out that ideas can simultaneously be co-opted and distorted. Thus when genetics is co-opted for eugenics, or statistics for bell-curve arguments, or Bayes’ theorem to comment on the existence of a historical Jesus, or fine-tuning for supporting ID, it does not imply that those doing the co-opting are using the ideas properly. Nor does it imply, in and of itself, that they aren’t.

4 Susskind was asked by Amanda Gefter at New Scientist: “If we do not accept the landscape [multiverse] idea are we stuck with intelligent design?” Susskind responded (rather clumsily, in my opinion): “I doubt that physicists will see it that way. If, for some unforeseen reason, the landscape turns out to be inconsistent - maybe for mathematical reasons, or because it disagrees with observation - I am pretty sure that physicists will go on searching for natural explanations of the world. But I have to say that if that happens, as things stand now we will be in a very awkward position. Without any explanation of nature's fine-tunings we will be hard pressed to answer the ID critics.” I only bring this up as an example of scientists using the fine-tuning problem as a motivation, at least in part, for their multiverse research.

5 The puddle argument (a sentient puddle observing just how perfect the universe (a pot hole) is for its existence, ergo god) is perhaps relevant for privileged planet debates (isn’t our planet just perfect for human life?) but not for cosmic fine-tuning which addresses the very building blocks (heavy elements) for any kind of life.

Tuesday, January 7, 2014

Friday, January 3, 2014

A physics problem and test of LaTeX

Let's look at a problem accessible to students taking their first course in physics.

An object is on a horizontal table, 1m from the edge. It is pushed so that it travels the 1m in 2s, then falls off the edge of the table. Is it likely that the object was on wheels?

Reasoning: Let's imagine giving the object a push and it slides (no wheels). Let's compute the maximum coefficient of kinetic friction using the simple model of friction we learned. Let's also neglect another type of friction, air resistance (which would be much smaller than sliding friction.) Consistent with the problem description, the maximum friction would occur if the object just makes it to the edge before it falls off the edge. Mathematically we can say that the final speed is zero, or \( v_{f}=0\). We can then compute the initial speed to be $$v_{avg} = \frac{1}{2}(v_{i} + v_{f}) = \frac{\Delta x}{\Delta t}$$ so, using \( v_{f}=0\) and \( \Delta x=1m\) and \( \Delta t=2s\), $$v_{i}=2\frac{1m}{2s}=1m/s.$$ We can then get the acceleration: $$a=\frac{v_{f}-v_{i}}{\Delta t}=\frac{-1m/s}{2s}=-\frac{1}{2}m/s^{2}$$ This acceleration, by assumption, is caused by kinetic friction. Here we have the simple case where the normal force is equal to the weight, so from \( F = -\mu_{k} N = -\mu_{k}mg = ma\) we get: $$\mu_{k} = -\frac{a}{g} = \frac{0.5}{9.8} = .051$$ Looking at a table of coefficients of friction, we see that this is a very small value, in the range of lubricated metal or ice on ice. So it is a reasonable guess that the friction is so low that the object was rolling, not sliding.

Thursday, January 2, 2014

Hey Al Mohler, read this!

(Boldface added.)

That was written (and spoken) by the greatest Baptist preacher of all time, Charles Spurgeon. In 1855.



