Natural Science #13: The Fermi Paradox

The universe is big. Really, really big. In our Galaxy alone, there are about 400 billion stars – 20 billion of which are similar to our own. Of those sun-like stars, about one-fifth have earth sized planets orbiting a habitable zone – not too far as to freeze, not too close as to burn. If only 0.1% of those planets developed life, there would be 1 million planets with life in our galaxy. And that’s just our galaxy.

This thought process was formalized and made famous by Frank Drake who proposed an equation to estimate the number of active, communicative extraterrestrial civilizations in the galaxy. Drake originally estimated the number of these advanced extraterrestrial civilization between 20 and 50 million.

So where is everyone? This was the question that Enrico Fermi posed in his famous paradox. If the universe is so large and old, and if it only took us 250 thousand years to develop radio communication and space flight, why then is there no evidence of intelligence elsewhere in the universe?

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Natural Science #12: Square-Cube Law

In 1638, Galileo Galilei described a simple law:

The ratio of two volumes is greater than the ratio of their surfaces.

To understand what Galileo was talking about, just imagine a cube. If you double the size of a cube, the surface area increases by the square of the length (2len2) and volume increases by the cube of the length (2len3). The surface area will be 4 times larger (22 = 4) and the volume will be 8 times larger (23 = 8). The ratio of volumes is greater than the ratio of surfaces.

The square-cube law says that as a shape grows in size, its volume grows faster than its surface area. This turns out to be a powerful idea for many scientific fields. For example, in mechanical engineering, it explains why a scale model engine won’t account for the heat loss of a full-scale engine, or why an airplane’s wings need to scale faster than the planes fuselage, or why building taller and taller skyscrapers is increasingly difficult.

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Natural Science #11: Kinetics

In light of the NFL season starting today, let’s consider the action that occurs around a line of scrimmage. A defensive line crashes into an offensive line – hoping to find a gap that allows access to the quarterback, while simultaneously trying to close gaps that allow access for the running back. The offensive line does the same thing but in reverse. Most of the time, the two lines crash in a stalemate – no quarterback is sacked and no rushing yards are gained.

But if we are talking about the Seattle Seahawk’s defensive line, they probably crashed into the offense in just the right way to cause a reaction that would end with a quarterback laying on the ground. If we are talking about the Dallas Cowboy’s offensive line, they probably crashed into the defense in just the right way to allow Ezekiel Elliot a passage into the end zone.

Chemical reactions basically work the same way. Atoms and molecules flow around the environment and occasionally bump into each other. Like with football, these collisions usually result in nothing happening. But if they collide in just the right way – with enough force and at the right angle – a chemical reaction occurs. Today’s post will explore kinetics, the science of how those collisions affect the rate of reactions.

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Natural Science #10: Entropy

Back in the 19th century, at the height of the industrial revolution, engineers were pondering questions about the efficiency of steam engines. From those questions, arose the science of thermodynamics. You might be familiar with the laws they came up with:

  1. Energy cannot be created nor destroyed in an isolated system.
  2. The entropy of any isolated system always increase.
  3. The entropy of a system approaches a constant value as the temperature approaches absolute zero.

Today’s post will explore that second law of thermodynamics, which also happens to be the most important for understanding time and the evolution of the universe.

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Natural Science #9: Critical Mass

Imagine a cloud of gas floating in space. Over centuries, the cloud collapses under its own gravity and what happens next depends on how much matter was available. In one case, we might end up with a Jupiter or Saturn like ball of gas floating around. Given a bit more matter, we end up with a brown dwarf – a sort of failed star. But at some point, adding a bit more matter causes a drastically different outcome. A thermonuclear reaction lights up the sky.

The amount of matter needed to form that star is called its critical mass and it’s the subject of today’s post.

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Natural Science #8: Population Genetics

So far, we’ve talked about Mendelian genetics and Darwinian natural selection. Combining the two, we get population genetics. Population genetics is the study of the distribution and change in frequency of alleles within populations, and is the foundation of modern evolutionary biology.

In this post, we will explore how the mathematical foundation of population genetics was formed and what causes populations to change over time.

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Natural Science #7: Natural Selection

In the 1830s, Charles Darwin embarked on a surveying mission around the world aboard the HMS Beagle. Darwin, a naturalist, observed many organisms during the journey; none more famous than the finches of the Galapagos islands.

Darwin observed that each island’s species of finch had beaks that were uniquely adapted to the type of food that was available on that island. For example, if there were insects, the beaks would be skinny and pointed. If there were hard nuts, the beaks would be thick and strong.

In 1859, Darwin published his findings in The Origin of Species. He argued that evolution had occurred in the past and that natural selection was its primary mechanism. This post will explore that mechanism.

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