Chapter 9. Science
Introduction to Science
Science attempts to give us a better understanding of the world and of the universe. The universe is a very complicated place. It’s made up of so many different parts and systems. It’s not easy for us as human beings to understand our universe, but as a species we have gotten better at it over time. Our scientific beliefs and understandings have always been changing. In order to better understand science we’ve had to invent new tools, design new tests, witness new observations, imagine new hypotheses, make new discoveries, and report new findings.
In the first half of this chapter, I discuss science itself. In the second half, I explain some scientific concepts.
Why science is important
Science is important because having a better understanding of our world and our universe allows us to do more things. It also allows us to make more educated decisions. Science allows us to have more sophisticated interactions with our world and our universe. It helps us achieve things we wouldn’t have otherwise been able to achieve.
The Scientific Method
The scientific method is a list of steps that can be used to study science effectively. The steps include: 1. Wondering about a question, 2. Discussing a hypothesis, 3. Making a prediction based on that hypothesis, 4. Running an experiment designed to test that prediction, 5. Analyzing the results of the experiment to make logical conclusions about the hypothesis, and 6. Logically answer the initial question.
A hypothesis is a possible explanation or idea for how something works, but it still requires further testing before you can be sure.
The steps of the Scientific Method don’t have to happen in that order. Some steps can happen without you consciously taking those steps. For example, you might accidentally make a discovery. In that case, you didn’t intentionally make a prediction. But you did have an expectation and noticed when reality was different from your expectation.
The scientific method can be used to make new scientific discoveries, teach existing science, or test proposed scientific knowledge.
Why science is difficult
Science is difficult because many things that can go wrong can lead you to incorrect conclusions. The results you get from science are only as good as the methods and logics used to come to those results.
Good logic requires that you don’t have incorrect beliefs or assumptions. It also requires that you avoid drawing illogical conclusions from your information.
It’s possible to unknowingly be biased in a way that leads to incorrect assumptions. Wikipedia has a great list of cognitive biases and fallacies. Each describes a way in which our behavior or our logic can be irrational. You might even overlook an important fact. The phrase “bad science” is used to describe an experiment or study that we think is logically flawed or biased.
Scientists can publish their results and methods. If they do, other people can review and judge the logic, experiment design, and results. This can help identify flaws with the research. It may also lead to new ideas or explanations.
Science education
Our knowledge of science influences us. Some science education is practical, allowing you to apply what you learned to help improve your own life or your career. Science education can be fascinating and entertaining as well as informational. Science can be inspiring. It shows us things we never imagined before and it inspires us to ask new questions.
There are lots of different kinds of science education. Educational materials can be aimed at children, students, or adults. The better our educational material, the better our understanding of science will be.
Scientific writing can be difficult to read
I like to read scientific papers. But sometimes scientific papers and writing can be difficult to read. One of my pet peeves is when I have to work really hard to understand what I’m reading. I’ll find an article that I know has great information, only to get frustrated at how it is written.
Scientific papers tend to include an “abstract”, which is a concise summary of all the important points of the paper. But even these are sometimes difficult to understand!
Simplification and accuracy warning
In the next few sections I will try to explain some scientific topics. These are meant to be brief introductions to these topics, not a detailed and complete explanation. Some details are left out to make the explanations more concise.
The speed of light, radio waves, electricity, and sound
Light travels extremely fast. The speed of light in a vacuum is approximately 300,000,000 meters per second, which is about 186,000 miles per second or 670,000,000 miles per hour. To put that into perspective, the distance from one side of the United States to the other is about 2,600 miles, so light would only take light 0.014 seconds to travel that far. That’s 1.4 hundredths of a second.
Radio waves, electricity, and sound all travel very fast too. Radio waves are a form of electromagnetic radiation so they can travel at lightspeed. Electricity also comes from electromagnetic radiation so it could travel at the speed of light, but in practice it is conducted through wires so it is much slower than light in a vacuum. The speed of sound is about 768 miles per hour.
I’m often amazed at how quickly computers can perform instructions and send information across far distances. These high speeds in physics help explain how our technology is able to do so much in a short amount of time.
Definition of “Theory”
One of the most frustrating misconceptions is the definition of the word “theory”. The word “theory” has a VERY different meaning to scientists than how it is commonly used.
In casual conversation, to have a theory about something means to guess or suspect something that you haven’t yet proved or disproved. When talking about science, to have a theory about something means that all of the logic and evidence supports the idea, and that you HAVE already done lots of research to prove or disprove it.
So calling something a scientific theory generally means that there is strong evidence for something, not weak evidence. I bring this up because so many people say, “Evolution is just a theory that means it isn’t proven” when really there is a lot of evidence that supports evolution.
DNA
There are about 37 TRILLION (37,000,000,000,000) cells in your body. Each of those cells contains a nucleus. Each nucleus contains its own copy of your entire DNA sequence. Your DNA is organized as 46 chromosomes in 23 pairs. Each of these chromosomes has a double-helix shape like a twisted ladder. The rungs of the ladder are made up of two molecules which together are called base pairs. There are about 30 billion base pairs in total among those 46 chromosomes. That means the total number of base pairs across all the cells in the human body is about thirty-seven trillion times thirty billion, which comes out to be 111,000,000,000,000,000,000,000 base pairs.
We typically think of our DNA as being very tiny because it is so small compared to us. But our DNA is enormously large if compared to things that are much smaller than it, such as electrons. DNA might be easier to understand if you stop thinking of it as something really small and instead start thinking of it as something really big.
The nucleus in your cell is like a giant factory for manufacturing proteins. A gene is a sequence of base pairs that acts as a blueprint or mold to build different proteins. The proteins can be used to build other materials. The cells in your body are so good at construction that a single cell can manufacture a complete copy of itself if it has the proper conditions. These giant factories and construction sites are all run by physics and chemistry.
There are four possible bases that we label A, C, G, or T. These pair up to become base pairs and build the rungs of our DNA ladder. An A is always paired with a T and a C is always paired with a G. However, the order of the pair matters since it determines which base is on which side — an AT base pair will have a different effect on forming the protein than a TA pair. So in a DNA sequence there are four possible base pairs at each step of the way: AT, TA, CG, and GC. To simplify how we write out a sequence of base pairs, we only write the first letter (A, C, G, or T) since we can infer what its partner is.
Genetics
Your DNA, the thirty-billion base pairs, determines your genetics. Your DNA sequence is influenced by your family tree. It is a combination of your father’s DNA and your mother’s DNA. Your DNA is extremely similar to your family members. Your DNA is mostly the same between you and all other humans. In fact, your DNA sequence is about 98% the same as that of a chimpanzee. Your genetics determine which traits you exhibit.
Your DNA also contains genetic mutations. A mutation occurs when a gene is copied but there is differences between the original and the resulting copy. This creates genes that are slightly different from either parent.
I see some similarities between a computer running a computer program and a cell making proteins from its DNA sequence. They both rely on details encoded in a sequence (the 1s and 0s of the computer program vs. the base pairs of the DNA). But they also rely a lot on the environment that is being used to examine the code (the operating system and hardware of the computer vs. the cell and its mechanisms).
Epigenetics
The genes in your DNA are used to build proteins. The gene acts a template or blueprint for the design of a protein. A single template can be used many times to make many copies of the same protein. When a gene is used to build a protein, this is called gene expression. By determining what proteins can be made, your genetics influences who (and what) you are. Proteins are used to build and operate the living organism.
What causes gene expression to occur and a new copy of a protein to be constructed? It’s actually really complicated. And really important because changes in which genes are expressed and how much each is expressed can have a big effect on the organism. So the characteristics of a living thing can change due to changes in gene expression despite the underlying DNA remaining the same. The genes in your DNA can influence who you are, but so does the expression of those genes. The study of how gene expression is controlled, and other influences on an organism besides a strict reading of the genetic code, is called “epigenetics”.
Nature vs. Nurture?
“Nature vs. Nurture?” is a very well known question. This question asks whether a trait is the result of the genetics we began with at conception or a result of an influential event.
Your genetics come from your parents. But your parents also influence you by how they raise you. So your parents can have a big effect on both your nature and how you were nurtured.
Your traits can be influenced both by genetics and your experiences.
Evolution
Evolution is the idea that a new species can develop from an existing species over many generations. The new traits for the new species come from genetic mutations and new combinations of DNA. Charles Darwin first discovered evolution when he was studying populations of animals in the Galapagos Islands. He understood that new generations of animals were inheriting traits from their parents as well as developing their own traits. Later scientists, after studying DNA, discovered that DNA was responsible for genetic traits and evolution.
New genes can spread very quickly if the genetic trait helps the living thing reproduce in large numbers. In this case, we say that the trait is well-adapted for its environment. On the other hand, a species goes extinct if it dies off rather than continues as new generations. In that case, we might say it is poorly adapted to its environment. There are lots of reasons why a species might go extinct (changes to the habitat, food sources, predators, etc).
By developing new species from pre-existing species, evolution creates a family tree of different species. Species that are more closely related to each other on the family tree will have similar traits. For example, all mammals have a lot in common.
“Survival of the Fittest”
Darwinian evolution is sometimes described evolution as “the survival of the fittest”. But this phrase is confusing and can be misunderstood. A more precise way of saying it would be “the least fit don’t survive”.
To understand the difference, imagine a creature or plant species that only lives on a single island, but shows no sign of going extinct. In that case, Darwinian evolution would consider it to be one of the fittest species because it is more fit than the species that went extinct. Some people might incorrectly think that because the habitat is limited that the species is not very fit. Or maybe they incorrectly think the species is not fit if it is not very impressive or powerful. But a species is fit as long as it isn’t threatened to go extinct.
(Herbert Spencer is credited with coining the phrase “survival of the fittest” to describe Charles Darwin’s ideas.)
The origins of the human species
It’s estimated that modern humans (homo sapiens) began at least 200,000 years ago. Other related species came earlier than that. If you go back enough generations before humans, you’d arrive at a species that was an ancestor to both humans and chimpanzees. If you go really far back, you’d arrive at a species that was an ancestor to all mammals.
It is incorrect to say that humans evolved from monkeys. The monkeys that we have around today were not our ancestors. Instead we should say that monkeys share a common ancestor with us. Chimpanzees are our distant, distant cousins but we did not descend from chimpanzees.
Chimpanzees (and bonobos) are more closely related to us “homo sapiens” than any other species currently living on Earth. But they are not the species most closely related to us out of all species ever. During Earth’s history there have been many other species that are more closely related to us than chimpanzees, but none of those species are still alive today. They died off for various reasons, including competing with homo sapiens for food and territory. We have found fossilized skeletons of these other species and they have similarities to humans but also some similarities to monkeys.
Beginnings of life on Earth
The term “evolution” describes how one species can lead to a different species or multiple different species over time. Evolution explains how we arrived at the diversity of species we have today. However, evolution has nothing to do with how life began. The term “Abiogenesis” is used to describe how life can form from non-living material.
Scientists estimate that this happened on Earth about 4 billion years ago. The earliest living things were very simple and very different than the living things alive today. The Earth was also very different back then. When life began, there would been have a lot of time for many chemical reactions and events to occur uninterrupted. Today it would be much more difficult for abiogenesis to take place. The material would get eaten or absorbed or destroyed long before it had time to develop into life.
Different fields of science
The topics in this chapter focused on biology, chemistry, and genetics. However, there are many interesting fields of science that aren’t mentioned here: mathematics, computer science, etc. Each gives us greater understanding about how things work.
The future of science
The universe is such a complicated place that humanity still has so much to learn about it. New scientific ideas are being discovered and investigated every day. I think that we will learn so much about science over the next one hundred years. We may be nearing a time in human history when we make unprecedented scientific progress.
