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Tag Archives: hypothesis

Bill Nye, Popular Guy

Bill Nye was on The Bill Maher Show tonight.He’s been very popular the past week or two, appearing in a debate on evolution and the viability of intelligent design, he spoke about climate science with Marsha Blackburn on Sunday’s Meet the Press, and now Bill Maher.

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Teddy Roosevelt and party at the tree, General Sherman.

On Maher’s show Nye was asked how it is that we know the world is older than 6000 years. Or to rephrase, “How could we know if a tree is older than 6800 years old?”

It’s actually a good question.  It’s a good question that gets to the crux of what Bill Nye was engaging Ken Ham on: how do we know things?

To address that big question, let’s talk about how we would answer the smaller one about the tree and see if that gives us any insight into how we gain knowledge…

Every kid has heard that the rings in a tree stump correspond to years that that tree lived. But how do we know?

ImageForestry.about.com tells us that, “The new, large cells that are produced the following spring are easily distinguished from the previous year’s tree growth as a distinctive ring. A ring composed of a light part (spring growth) and a dark part (late summer/fall growth) represents each year’s growth.”

If you want to test this method for dating trees, the best place to start is to find a tree that you know was planted at a certain date. Perhaps in a housing development, something you planted yourself, something your parents planted, or better yet… get some trees to plant this year and come back in a decade or so. 

ImageOver the course of a decade or so, cut one of your trees or use an increment borer to take a sample that includes the pith (the centermost section of the tree). Now count the rings. While you’re at it, consult some records that can tell you the weather patterns over the time that this particular tree lived. With this information, you can now cross-reference your tree ring data with weather data. If you have bores from your trees over successive years, you can line your samples up and compare. Do the older trees have more rings? Do all of your trees have numbers of rings corresponding to their known age? Do you see any weather-related patterns in your ring spacing? Do all the trees have the same weather patterns for the same years?

What I’m proposing is, you can adopt the hypothesis that trees make a ring every year and then test it just as we described above.

If you do this, you’re doing science. You can see the data yourself, see how the data supports or refutes the hypothesis you made. You don’t need any outside help, you just need time and access to some trees (and perhaps the equipment that enables you to get your data).

Now ask yourself, ‘do you believe your data? Do you think it supports your idea? What experiment would give you the best opportunity to change your mind about this?’

Now do that experiment.

And call yourself a scientist while you’re at it.

You aren’t just answering the question that started this column. You are seeing how scientific method works and getting a glimpse into the way that we learn from the world around us.

 
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Posted by on February 18, 2014 in Uncategorized

 

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What can we prove?

Evidence mounts in the strange case of proving that Kevin Bacon, the man who is seven degrees from everyone, has never been to the Liberty Bell in Philadelphia.

The hypothesis: Kevin Bacon has NEVER visited the Liberty Bell

Evidence:

Exhibit A: Kevin Bacon standing in front of a VW beetle – not the Liberty Bell

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Exhibits B-E: The Liberty Bell with accompanying visitors, none of which are Kevin Bacon

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Exhibit F: The Liberty Bell, yet again, without Kevin Bacon anywhere in sight

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Conclusion: Hypothesis accepted – Kevin Bacon has NEVER been to the Liberty Bell

 

What’s wrong with this argument?

Special thanks to Paul Offit, MD, whose Coursera Vaccines Class inspired this investigation

 
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Posted by on October 16, 2013 in Uncategorized

 

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Theory, Hypothesis, Fact

A conversation with one of my students got me to thinking about how science is done and the distinction of the ‘Theory’. Time and again this idea comes into question because the layman’s definition of a theory is very different from the one used in science.

There are a large number of deifinitions of ‘Theory’, but I think that the one that most people have in their heads is this: “an unproved assumption.” I tend to favor one more like this: “a working hypothesis that is considered probable based on experimental evidence or factual or conceptual analysis and is accepted as a basis for experimentation,” however, even this suggests much less conviction than a scientist would mean when they used the word. Personally, I think the inclusion of the word ‘hypothesis’ reveals this because this is something altogether different in the vocabulary of a scientist.

Webster again: Hypothesis – “a proposition tentatively assumed in order to draw out its logical or empirical consequences and test its consistency with facts that are known or may be determined.”

A working example of how these two terms relate…

ImageThe Germ Theory states that some micro-organisms cause some diseases. Someone working on Germ Theory may have a hypothesis that some microorganism ‘X’ causes disease ‘Y’. Germ theory is the overarching idea of organisms causing disease (fairly well established), the hypothesis is that ‘X’ causes ‘Y’.

This is a nice example, because there is a well-known series of experiments that outline what steps to take to test if this hypothesis is supported. Robert Koch (http://en.wikipedia.org/wiki/Robert_Koch) outlines these in the 19th century and they keep his name, Koch’s postulates.

These postulates state that to establish that an organism is the cause of a disease, it must be:

  • found in all cases of the disease examined, while absent in healthy organisms
  • prepared and maintained in a pure culture
  • capable of producing the original infection, even after several generations in culture
  • retrievable from an inoculated animal and cultured again.

If all of these hold, then we say that this hypothesis has support.

Another hypothesis that has been under investigation lately is how the existence of the Higgs Boson could provide more support for the Standard Model (part of The Atomic Theory).  Recent News of this has been reported on BBC at : http://www.bbc.co.uk/news/science-environment-21785205. The AAAS provides this chart (you can think of it as the Periodic Table for elementary particles):Image

 

How does this ‘test’ anything? Basically, the Higgs Boson is required in order for the standard model to be correct, i.e. it predicts the existence of this particle. 

The hypothesis is that this particle exists as predicted, the Theory is the larger structure that encapsulates this hypothesis.

Altogether, the workings of the Higgs Boson/ Higgs Field underlies our conception of why atoms have mass. Although there is more to it, this also leads to a somewhat better idea of why there is gravity (another Theory).

Oh, and ‘Fact’. That doesn’t really exist. Maybe mathematics…?

 
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Posted by on March 14, 2013 in Uncategorized

 

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Aside

ImageScientific method as a lens to view the world                     

Science has a problem in telling its stories to the world. The problem stems from the way that science is done and the way its discoveries are published in academic journals not known for their mass appeal. In science, seeing something happen once or hearing about an occurrence might lead one to get in the lab and ask a question, but it is never itself acceptable as an answer. Instead, multiple repetitions of an experimental question are asked until consistent results are found under controlled conditions. Compare this to watching the news or reading the paper and you’ll find a drastic difference. Mass media loves the anecdote of ‘one family’s story’ or ‘what happened to my kid.’ Stories appeal to our natural tendency to relate to people and to incorporate the underlying morals or lessons into our broader worldview. He-said-she-said arguments are presented as fair and balanced even when balance is unjustified. With this in mind, consider this story of how the birth of the scientific method changed the world we live in.

The events of the late 15th and early 16th centuries ushered in a new age. Not just in the discovery of new land to be conquered and populated by western civilizations, but also in the way westerners saw the world and their place in it. Suddenly there was half a globe of terra incognita. As Columbus revolutionized our geography, Copernicus and Galileo revolutionized astronomy. But what was good for cartographers and astronomers wasn’t so good for the royalty and the church, who had been comfortably enjoying in the status quo.

At that time, the vast majority of people were ruled by the very few who held their power by divine right. What they said was both fact and law and any who differed in opinion did so at their own peril as autocracy seldom views challenge or change as good.

But cracks were beginning to show.

Between the discovery of the west and the mounting evidence for heliocentricity, came the greatest schism the Christian church has ever seen, hammered home when Luther nailed his 95 theses to the church door in Wittenberg, Germany 1517. Within a century a new world was discovered, the earth was shifted from the center of the universe to a body orbiting the sun and even God’s own voice on earth was being challenged due to a poor financial decision granting the sale of indulgences. How unfortunate for those in power that the printing press, which Johannes Gutenburg had introduced a half century earlier, made it so easy for this news to circulate around the globe amongst a newly literate population.

By the middle 17th century, Bacon and Descartes were formalizing the rules of logic and, more specifically, of scientific inquiry. Their texts, Novum Organon and Discourse on Method display a new desire for evidence-based reasoning rather than simply accepting facts ad hominem – even in cases where the hominemis the Pope himself. Bacon wrote, “The logic now in use serves rather to fix and give stability to the errors which have their foundation in commonly received notions than to help the search after truth. So it does more harm than good.” That is, too much effort is being spent defending what we already think is true rather than just following what the data tells us. This is exemplified by Ptolemy’s

How Ptolemy saw the solar system

complex system of interlocking circles and the complex movements they require in order to explain the wanderings of the planets in the night sky. An excellent demonstration of this backwards logic can be found at http://people.highline.edu/iglozman/classes/astronotes/retrograde.htm

With the upset in worldview brought by the renaissance and its new rigor for asking scientific questions along with a few intervening centuries, one would think that we would be more discerning in our beliefs today. We should be open to new ideas that challenge accepted dogma, and be in possession of tools to discriminate between unfounded speculation and well-supported theories.

Or, perhaps not.

In many ways, we are just as easily swayed by ad hominem arguments, faulty logic and satisfaction with the status quo as we were seven hundred years ago.  But it’s not entirely our fault. We’re not built to think critically, rather, we make quick judgments based on what we see in front of us. The ability to make split second decisions were likely required to save our skin in the time of Hobbes’ “state of nature.” While labored, methodical reasoning would reason us right into the lion’s mouth. The difference today is that we are vastly more educated than our forbearers, possibly smarter -if rising IQ scores can be taken at face value- and, frankly, we do have the time to practice methodical reasoning. Rarely do we need to make life saving fight or flight decisions in modern life.

Science has taught us that the universe may not be as we see it. In fact, our senses are fooled all the time. Sticks don’t bend when we put them in water, a continuous tone may appear to change pitch as the source approaches or recedes from the observer and quantum mechanics tell us that all the matter of the world is nothing like what it appears to be. Our senses tell a variety of lies to us, but nature does reveal her laws with careful study.

Understanding scientific method is teaching oneself to remain impartial to results of experiments, to ensure that the tests applied are rigorously designed to disprove  – rather than support – your hypothesis, and to rely on the power of statistics to interpret your results rather than being swayed by anecdote or a desire to see a predetermined outcome. None of this comes easily. As I said above, we are a storytelling people, stories are the lenses through which we view the world. It’s a lot easier and exciting to believe an anecdote than it is to understand the truth. But it’s often worth the effort and sometimes there might be an interesting story behind the science too.

An old essay I wrote about the scientific method

 
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Posted by on October 20, 2012 in Education

 

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