07 January 2011

What's in a theory?

One phrase that bugs me, and many scientists is the commonly misused "It's just a theory."  I don't need to point out to you all the idiotic ways that this phrase has been used, as I'm sure most of you are familiar with some of them already.  Plus, I'm not writing to tear apart those who don't understand science, more to help clear it up to all of us.  So, I recently came across the image you see above.  It think it is one of the clearest and easiest ways to see how the scientific process works.

In the scientific world, theories are not just whatever explanation someone dreams up.  An idea must be supported by data and observations or it is thrown out before ever becoming a theory.  There is a clear difference between the scientific definition of a theory and the common use of the word.  A scientific theory has been verified against the data and is generally accepted as an accurate explanation of the observations.  Better descriptions that I can do are here and here.

But a theory is not fixed and final.  Theories are often modified as new discoveries are made.  That is one of the key ways that science continues to move forward.  A theory is updated until it can not be changed to fit the data, then a new theory is started.  And even then the previous theory may not be invalidated, it is just modified to only apply to certain cases.  There have been a couple of recent high profile cases where some claimed we should abandon a theory based on one piece of evidence that does not fit.  But that is not at all how science works.  A theory is only thrown away when another comes along which explains more, and does it more accurately.  They are not discarded without a scientifically proven replacement that does the job better, even if we know they are not yet perfect on their own.

Often, theories remain even after they have been disproved.  Though difficult to imagine, science is not very concerned with the absolute truth.  Instead it looks for the ideas and methods that most accurately predict what happens.  For example, say scientists are trying to determine what is that the center of a black hole.  No light can escape so we can not observe it directly.  If scientists were only concerned with the truth, they would abandon research, because finding the true answer will likely be impossible.  But what scientists are really looking for is some explanation of how the black hole acts that agrees with all of the data, regardless of whether their idea is actually what they would find in the center of the black hole.

The best theories are ones that fit what we observe in the universe, not some kind of universal truth.  It is the reason the Bohr model is still taught in high school science, even though it was proved obsolete by quantum mechanics.  Then there is my favorite example: gravity.  Guess what, Newton's theory of gravity is wrong.  It does not work at very small or large distances or high speeds.  Einstein's general relativity replaced it, but even that did not make it irrelevant as a teaching tool or an easy way to make most calculations for the conditions we deal with.  

The point here is that science looks for the methods that work best for predictions, however well that may be.  Theories are not thrown away with no replacement if they are found to be imperfect.  We will continue to teach those that are most useful, and when science develops a theory, know that is has been tested against the data.  But even then, that theory may be universally accurate, or it may only work under a small set of conditions.  So the phrase "Just a theory" is not just misused on scientific ideas, it really does not mean anything at all.  The only thing to throw out is any argument that begins with that phrase.

22 December 2010

Giant Sinkhole is not Technically a Sinkhole

In case you missed it earlier this year (end of May), here is some info and pictures from the sinkhole that appeared in the middle of a Guatemala intersection. The views of the thing are really amazing.
May 29, 2010 Guatemala City Sinkhole (Business Insider)
The hole was 100 ft in diameter, and 300 ft deep. You can see from the pictures that looking into it is like staring into the abyss. Somewhere down there is a clothing factory which used to be on the corner of the intersection. So how did this thing happen?

On May 29th of this year, the remains of tropical storm Agatha caused record rainfalls of over 14 inches in Guatemala City, backing up sewer systems. The hole was probably caused by a sewer line that backed up and started to leak, and ash from recent volcanic eruptions may have helped clog the pipse. But a leaky sewer won't make a hole like this just anywhere. Guatemala City is built in a steep valley, with bedrock forming a deep-V.  The bottom of the V is filled in with hundreds of feet of pumice-fill, which is loose gravel like rock from volcanic eruptions. Most of the city is built on the pumice-fill, which is easily eroded and can wash out down to the bedrock, up to 600 feet below. In fact, this is not the first time this has happened.

While amazing, neither of these holes are technically sinkholes. Sinkholes are formed from natural water erosion of bedrock (limestone or sandstone usually). The Guatemala "Holes" are not formed by natural water erosion, nor are they formed in bedrock. Unfortunately, geologists couldn't come up with a better term than "piping feature", so sinkhole is probably going to stick.

05 December 2010

Links: Alien bacteria found (not really)

The bacteria was found at this lake.  (Beautiful pic) (NASA)
So I am a few days late on this.  On Thursday, NASA announced that they discovered a new type of bacteria that makes us reexamine the conditions necessary for life to exist.  The discovery was a bacteria that can use arsenic instead of phosphorus in it's DNA.  Here is a link to the NASA release

So what.  Well, the DNA, which contains the blueprint for an organism to grow, of all previously known life on Earth is made up of only six elements, Carbon, Hydrogen, Oxygen, Nitrogen, Sulfur, and Phosphorus.  When astronomers search for lift on other planets, moons, or around other stars, they look for conditions that match what we think life needs to survive.  The bacteria NASA discovered reportedly can substitute Arsenic for Phosphorus in it's DNA.  Arsenic is highly toxic to most life on Earth.  Previously, organisms have been discovered which can survive high levels of Arsenic, but this is the first claim of one using it to build it's cells.  If true, it means it is possible for life to exist with a different set of conditions than we had thought.  Very important for those searching the galaxy for life, because not only can the be open to locations with high levels of arsenic, but they have some evidence that even more combinations of elements could lead to life.  This is really exciting for scientists and science-fiction readers/writers, who for years have hypothesized that there might be life out there built on different block than we are.  We now have some evidence that is it possible.  Maybe.

While the news is very exciting, a few places on the internet have gone a little overboard.  First, the claims of the bacteria actually using the Arsenic in their DNA is not quite confirmed yet, it is just the most likely hypothesis as of now.  It absorbs Arsenic and grows in it's presence, but many more tests are needed to confirm that it actually uses it in DNA, and how it does it.   Nature has a good review

Second, there is no evidence that this bacteria is alien in origin.  At least not any more evidence than all life on Earth came from outer space.  See panspermia for more information.

Likewise, third, this is not evidence that life evolved more than once on Earth independently.  This bacteria is probably a mutated form of other previously existing bacteria species, but this has not been proven either way.  The lake where it was found was connected other water sources just 10's of millions of years ago, it has not been isolated since like began to develop billions of years ago.

Finally, I do think there is one other implication here that seems to be missing from some discussions.  If we have been studying life on Earth and evolution for hundreds of years, and just now found something that may cause us to modify our definition of what is necessary for life, what does it say about our efforts to find life in other places.  With it so much more difficult to make observations on Mars, around Jupiter, Venus, or any other planet, who knows what exists that we have just not come across yet.  Just because we didn't find life in our first observations on Mars, we can't be sure we have ruled out life being somewhere on that planet.

Here are a couple of the stories explaining the news.

Yahoo News
Mercury News
Popular Science

24 November 2010

Why you get tired after Thanksgiving dinner. Hint: it’s not Tryptophan.

Really the only thing that doesn't make you sleepy
You know the story. Have thanksgiving dinner in the middle of the afternoon, eat right up until you start to feel sick (and maybe a little more), and then find a couch or chair and fall half-asleep. If it happens, it's likely that someone will blame it on the Turkey. The old myth is that Turkey contains the amino acid tryptophan, which causes drowsiness. None of that is actually false. Turkey does contain tryptophan. And tryptophan is related to sleep – it is the only amino acid that can be converted to serotonin, which regulates our sleep patterns. But take a look at this list. Pork, chicken, and peanuts all have as much or more tryptophan as turkey. And beef and eggs are comparable too. But you don't hear people complaining that they are falling asleep because of the chicken sandwich they had for lunch. So what does make you sleepy at 6pm on Thanksgiving? The answer is: carbs. Think about the rest of the stuff on your plate: mashed potatoes, stuffing, cranberry sauce, breads, sweet potatoes, pie… maybe some vegetables (but who really eats those?). Most of what you eat at thanksgiving is carbohydrates. And the research shows that high carbohydrate meals cause sleepiness by releasing insulin, which releases much more serotonin than you get from the tryptophan in turkey. So now, thanks to my help, when someone at your thanksgiving dinner tomorrow claims they are falling asleep due to the turkey, you can be the annoying nerdy guy who tells them they are wrong. Or just have another piece of pie.

01 November 2010

How 3-D TV Works

You have probably looked at 3-D images before with those goofy red and blue glasses. You may have even watched something in 3-D before. Maybe in a movie theater, maybe a TV broadcast from past years. I have done all of these things, but I still thought of 3-D movies or TV shows as a clunky gimmick. So it's a surprise to me as I keep seeing news stories about 3-D TV's. I wanted to know why, all of a sudden, everything needs to be watched in 3-D. As I figured, it comes down to technology.

How This Stuff Works

3DTV's - Not really like this. (MarkWallace)
Most 3-D technologies work by giving the viewer a different image for each eye. Differences in the images give an illusion of depth and make objects appear to be popping out from the screen. 3-D content is easy to produce, just by recording the same thing with two camera lenses in slightly different positions. It is easy enough to be used for many sporting events now. The trick is getting separate images from the screen to each eye of the viewer.

The old red and blue glasses did this by tinting the two images, so the eye with the blue lens could not see the blue parts of the image, and vise-verse. But this messes with the colors and everything ends up seeming blurry, so it didn't catch on. Polarization is another method, used today in movie theaters. Read more here about light polarization. Put simply, two different projectors show images with different types of light, and filters on your glasses block one type of light for each eye. This method requires special coatings on the screen and technology to project two images at the same time, but general consensus is that polarization is the current technology with the best viewing experience.

A Collection of Technologies

The method used in the new home 3-D TV sets is neither of these, and unlike the previous methods, does not

08 October 2010

Issues: Coal Reserves

I am interested in looking at the future of energy. From an engineering perspective, providing electricity and the power for transportation is one of the great accomplishments in history. But it's clear that 100 years from now, it won't be done the way it is today. So I am curious about how it will be done, particularly for transportation. First I wanted to see where we are with the current methods, like fossil fuels. Coal provides about half of the electricity for the US and for the world, so let's see how much coal we have left. Sorry if this is a little long, but there was plenty of interesting information. Also, I am just trying to answer the question of how long would coal last if we kept using it, I am not trying to get into any discussions about political or environmental impact. At least not yet.

There is more energy available in coal reserves than in oil or natural gas. Coal reserves are also more widely distributed between countries of the world than other fossil fuels. Getting a handle on how much coal is left for the world to use is not simple. The most widely agreed upon number is around 900 billion tons, from the U.S. Energy Information Administration, the World Energy Council, and BP's annual report on energy assets. This number is the amount of "Proven" reserves, which is not the total amount of coal in the ground, but the amount that makes economic sense to dig up under current conditions.

Where is the Coal?  (Gunnmap)
In reality there are vast amounts of coal (and oil and natural gas) that we will never use. The EIA estimates that in the United States alone, there are between 2 and 4 trillion tons of coal in the ground, but only about 500 Billion tons are technologically feasible to mine, and only half of that is economically feasible. These reserves change over time – up from new discoveries of reserves, better technology to put more reserves in play, and the addition of more economically feasible reserves as coal prices increase. The 900 billion tons has been steady for a while, but it is more likely an overestimate than an underestimate, because reserve numbers are not updated very well. China, for example, is still using reserve numbers from 1992, despite having mined about 20% of that amount since then. In all of our time so far, humans have burned about one quarter of the coal that would make up our reserves today. Europe is down to less than half of what it started with. But given a need for coal and no cost-effective alternative (a poor assumption), it is reasonable that we could mine twice the amount we current consider reserves.

None of that answered the question of how long the questionable amount of coal reserves will last. If we assume those 900 Billion tons are all we can mine, then it will last about 120 years at current production. But worldwide coal production and usage has been climbing rapidly, at a little over 5% per year for about the last ten. If that continues, then the world will run out in 40 years.

That scenario is unlikely, even without a push towards renewable electricity. The growth will start to plateau at some point. But some growth will happen, and 120 years is very optimistic, even figuring we double the potential reserves with new finds. Any estimates that claim 250 years of coal reserves are either overly-optimistic, or are considering only the United States.

The United States not only has the largest coal reserves in the world (Russia is second), but is mining relatively slowly (though is still the #2 producer). At current rates, the US has a little over 200 years before current reserves are exhausted. Compare that to China, which has the third largest reserves, but is mining almost three times more than the US, meaning that they have only 41 years at current rates. The EU has 51 years. As other countries begin to run out, production in the US might pick up for exports, so it makes sense to analyze this globally.

All of this might be a needless way looking at coal production, because economic factors might be too important for the world to ever end up completely running out of coal. There is the idea of production peaks (see peak oil) for finite resources, where, well before a resource runs out, it climbs to a maximum production, then falls over time until the resource is depleted. Now, the reasons for this are both physical and economic, and honestly beyond me. A peak in coal production may happen well before 2050, followed by anything from a global crisis - if the need for coal stays but supply drops - to no problems - if the world smoothly switches to other forms of energy as production declines. A common estimate for this coal peak is 2025, but predictions vary wildly, and peaks are difficult to predict (I.E. the oil peak may have already happened, but we won't know for sure until we see a few more years of data).

So, regardless of any peak, somewhere between 60 and 80 years of coal is likely available if a major shift is not made in coal usage. But a major shift is what I am concerned about. Oil and natural gas reserves will run out well before coal, so an option to keep in mind, along with other alternatives, is to use coal to replace other fossil fuels, with coal-to-methanol or coal gasification. I might write about them later, but it appears that the numbers don't support these methods. Replacing oil with coal will reduce the reserves of coal faster and still put the year of depletion around the same time for either scenario. It may be worthwhile to discuss these processes from a standpoint of energy independence, so the US could cut down on oil imports, and again, I am ignoring (for now) everything about CO2 emissions. I'll get to some of those topics in another post.

13 September 2010

A Photograph of Philosophical Importance

Take a look at this photograph.

At first it might appear slightly interesting, a black and white photo, clearly from many decades ago. But this photograph is special because of its timing. This was taken way back in 1838, by Louis Daguerre as he was experimenting with the process to record images. It is of the Boulevard du Temple in Paris, and is one of the first photographs ever taken. Now the streets of Paris were not as empty as they appear here. Early photographs had to be exposed for several minutes (over ten for this one) to collect enough light, so anything that is not completely still for that time becomes a blur, and anything moving faster than a snail is invisible. Notice how blurry the trees are compared to buildings or streetlamps. This street was probably busy, but the moving people and carriages blended into the background. Except in the lower left. Let me zoom in. 


A shoeshine and his customer were still enough to be captured in this photograph. That makes this the earliest photograph of a person. Let me repeat that: Above is the very first photograph of a human being. Just something to think about.


11 September 2010

Anti-Aging Science

Most things with the words Anti-Aging attached would take quite a leap to be considered science.  But there is some real research in the area.  Here is something that looks like a mini-breakthrough.  A study has found a compound that was given to people as a dietary supplement, and may slow down the process of aging (but not stop or reverse it).  It works by activating enzymes in our body that rebuild parts of DNA (telomeres) which shorten over time and may play a part in making us old and wrinkly.  Telomeres also have something to do with AIDS, so this could be used as a treatment for AIDS patients also.  Read a more in-depth summary of the research here.