Wednesday, December 1, 2010
My latest paper got accepted for publication in the journal Development and I'm pretty stoked about it - a lot of time, energy, sweat, and even a few tears went into my most recent manuscript. After publishing, every scientist hopes that their work will be noticed and cited throughout the field. You can always go check online and see how many times your paper has been cited, or whether or not your paper has been deposited in the pubmed database.
Well, today I got a very nice surprise, however temporary it may be. One of the hottest topics in cell biology today is turning a terminally differentiated cell (like a skin cell) into a pluripotent stem cell (like an embryonic stem cell), which can then be used to make any other cell type you want. It's a pretty powerful phenomenon that promises to revolutionize regenerative medicine. The process by which a differentiated cell reverts back to a more pluripotent state is referred to as reprogramming.
Imagine my delight when, after going to the pubmed database and typing in "reprogramming" to see what the latest and greatest reports are saying, my very own paper showed up! Take a look at this screenshot:
Here are two zoom pics if you can't see it:
That's my name there - Cook MS! Now, as cool as this is, my excitement is a bit tempered for two reasons:
1) In a day or two, when the next paper with the keyword "reprogramming" comes into the database, my paper will be kicked out of the number one spot. It will stay in the list for "reprogramming", but everything is listed in chronological order of publishing date.
2) The subject of my paper was not directly about turning differentiated cells into stem cells, nor did we (the authors) list "reprogramming" as a key word. The work is on a very related topic, but we do not include any direct reprogramming experiments - it seems as if the paper is listed because it has implications for and we discuss reprogramming. Still cool, but it's not as if we're changing a paradigm or anything.
However, for today I will revel in the knowledge that despite all of the research going on in the entire world about one of the hottest topics in stem cell biology, my paper is temporarily listed as number one in the pubmed research database associated with the term "reprogramming".
Monday, November 29, 2010
On the upcoming 17th episode of the Pascals Bettors podcast, we have a Counter Creationism Corner where we discuss a common misconception that creationists put forth about evolution. A favorite claim by some creationists who try to dispute evolution is that “The second law of thermodynamics prohibits evolution”. Not surprisingly, creationists who claim this know just as little about thermodynamics as they do about evolution. Thomas Kindell, founder and president of Reasons for Faith Ministries, purports just such a claim that you can watch for yourself here - that is, if you can stomach even the first five minutes of it.
Most people don’t fully understand, and thus can’t question, the 2nd law of thermodynamics, but it has the allure of being one of the foundational tenets of a paradigm in physics, and people more readily question something that is referred to as a “theory of evolution” rather than a “law of thermodynamics”. The idea behind this argument is to present a seemingly longstanding scientific principle pertaining to a hard science, like physics, to topple the weaker, younger science of evolutionary theory. While this type of argument may have some emotional appeal, if creationists knew anything about the timelines of these two disciplines they would know why this is such a farce: Charles Darwin published his book, On the origin of Species, in 1859, but Darwin and others had put forth simple notions and publications about evolution much earlier. Although naturalistic thinking on biology dates back over 2600 years ago to the 6th century BCE with the greek philosopher Anaximander, proto-evolutionary ideas were set forth as early as 1745 by a few natural philosophers like Pierre Maupertuis, and later in 1796 by Erasmus Darwin, Charles Darwin's grandfather. Alternatively, thermodynamics emerged in the early to mid-1800s, largely due to the work of French physicist Nicolas Carnot, who believed that engine efficiency was the key to help France win the Napoleonic wars. It wasn’t until Lord Kelvin in 1854 that a concise definition of thermodynamics was recorded. Thus, even from the get-go, it seems that evolution has been around as long as, if not longer, than thermodynamics. BUT - this shouldn't matter anyways because it would be a logical fallacy to say that one science is more correct than another just because it has been around longer - so let's move on.
To begin our conversation about this topic, it is important to define our terms. Thermodynamics is the science of energy conversion involving heat and other forms of energy, most notably mechanical work. It turns out that, over time, several laws of thermodynamics have emerged. There are four well-known laws of thermodynamics: the zeroth, first, second, and third laws. The zeroth law is arguably the most fundamental of the four laws, but the need to state it explicitly was not understood until after the other laws had been formulated, in 1931. This law implies the definition of a temperature function, essentially demonstrating the possibility of constructing a thermometer. It is referred to as the zeroth because it is arguably the most fundamental of the four laws, but the need to state it explicitly was not understood until after the other laws had been formulated, in 1931. The first law (1850) is commonly expressed as the principle of the conservation of energy stating that the internal energy of an isolated system is constant - also commonly known as “energy cannot be created or destroyed” - this principle is at work in E=mc2, the equation that demonstrates the force of the atomic bomb, that matter and energy are interchangeable and the conversion of matter to energy is highly exothermic.
The second law (iterations in 1850, 1851, and 1909) states that heat cannot spontaneously flow from a colder location to a hotter location. This has to do with the universal principle of decay in the universe. The second law is an observation of the fact that over time, differences in temperature, pressure, and chemical potential tend to even out in a physical system that is isolated from the outside world. For example, this is how a space heater would work in your house - if you’re cold, you turn on the space heater - the heat produced in the heater is transferred to the air surrounding the heater which then increases in pressure and diffuses throughout the room until the air in the room produces a higher temperature equilibrium. As a result, you get warmer because the heat from the air is transferred to your body through contact. This is where it gets confusing. ENTROPY is a measure of how much this evening-out process has progressed, and entropy of a system not in equilibrium increases over time.
The word entropy is one of the most misunderstood concepts in thermodynamics, particularly by the creationists. It is a measure of the energy not available for work in a thermodynamic process. Think of it as diffusable heat in a room - the room itself is a closed system, until someone turns on a space heater - at this point, heat energy starts pouring in at one point in the room. According to the second law of thermodynamics, heat will transfer from the heater to the rest of the room. When the heater is turned off, the remaining heat will eventually diffuse and equilibrate throughout the entire room - as this happens, entropy increases until equilibrium is reached, at which point maximum entropy is recorded for the now closed system - but remember! This all changes if we turn the heater on again and create an open system with an outside input of energy.
The trouble with the word entropy comes in with its definition in the microscopic interpretation of statistical mechanics: entropy expresses the disorder or randomness of the constituents of a thermodynamic system. Unfortunately, many people walk away from this definition thinking that entropy = disorder on a macroscopic level. ENTER: the creationists! They think they are clever by saying “HA! You and I are complex and ordered! We could not have arisen through a process of evolution because the 2nd law of thermodynamics states that everything tends towards increased entropy, or disorder! HAHA!” This idea is absurd on its face for several reasons:
1) Disorder and entropy are not the same - the second law of thermodynamics deals with entropy. There are no laws about things tending to “break down”. There are no laws about disorder as people normally use the word. The 2nd law is about spontaneous heat flow or, more generally, about the impossibility to perform useful work indefinitely. The twists put on it by creationists, including “organized complexity” are entirely fictional.
2) All systems do not tend toward decay and disorder - on Earth, there are many systems besides evolution that tend toward greater order. Some examples are ice crystals and snowflakes, cloud formations, ripples in sand and water, cracks in drying mud, streams sorting stones based on size, growing plants when “left alone”, and the development of a human from a single cell. These are clear examples of order arising on Earth.
3) Complexity can form from simplicity - take the example of hurricane formation. This is based on the idea of a pan of water with heat applied uniformly to its bottom developing a convection current that is more complex than the still water. Complex planetary ring systems arise from simple laws of gravitation. Complex ant nests arise from simple behaviors. Complex organisms arise from simple seeds and embryos. A good mathematical example of this is the Mandelbrot set which describes fractals:
4) Earth is not a closed system - our planet is not an isolated system. There is a constant input of energy from the sun. Without the sun, it is clear that no life would be possible on our planet. Sunlight (with low entropy) shines on the earth, and heat (with higher entropy) radiates off. This flow of energy, and the change in entropy that accompanies it, can and will power local decreases in entropy on earth.
5) Even in a closed system, pockets of lower entropy can form if they are offset by increased entropy elsewhere in the system - the second law *does* apply universally (to our universe). But it allows for a local decrease in entropy to be offset by increases elsewhere. Intriguingly, the maximum entropy of a closed system of fixed volume is constant, but because the universe is expanding, its maximum entropy is ever increasing, giving ever more room for order to form. Cool, huh?
6) Increasing order is not a violation of the 2nd law, even temporarily. A violation would be a decrease in entropy without a greater increase in entropy to go with it. Neither growth or evolution violate the 2nd law because both take advantage of local differences in entropy to get work done. Evolution requires only reproduction, heritable variation, and natural selection - ALL OF THESE PROCESSES OBVIOUSLY OCCUR. THEREFORE, THERE IS NO VIOLATION OF THE 2ND LAW - if anything, the 2nd law would need to be re-written to accommodate the reality of evolution occurring.
In short, order from disorder happens on earth ALL THE TIME. Creationists who claim otherwise are either deluded or being intellectually dishonest. I'm not sure which of those is worse.