WHAT DO THE FACTS TELL US?

Unit Overview

The role of a scientist deals with making observations and collecting facts through observation. This may involve the use of complex instruments, such as an electron microscope or a particle accelerator used to study submicroscopic events. It may involve the use of the world’s most powerful telescopes to see a part of the past by observing the effects of explosions of stars that occurred millions of years ago. Once observations are recorded, it is the role of the scientist to try to make sense out of these observations and to come to some conclusion as to what these observations tell us. There are some areas of science in which disagreements arise as to how to interpret the observations or, even, what methods are best to use to make the observations. This lesson deals with some of these “problem areas” in science. They should not lead us to doubt the process of science but rather to realize that science involves both investigation and interpretation. Given time and enough study most areas of investigation will lead the majority of those studying it to similar conclusions. Questioning results is never wrong in science. It keeps those who are participating honest, and, also, very intent upon finding more proof of their conclusions. If enough proof is found, then other scientists will be more convinced of their conclusions. If not, then other explanations must be found.

Seeing is Believing?

There is an old expression that says “Seeing is believing.” This generally means that if we are told about something unusual happening, we may or may not believe it based upon how much trust we have in the truthfulness of the one telling us about the event. However, if we see it with our own eyes, we more than likely will believe it. Suppose you see two rather large containers filled with a clear liquid. A can of Pepsi is placed in each. In one container the can sinks, and in the other, the can floats. There has to be a reason for the difference. Upon close examination, you determine that one can is regular Pepsi and the other is Diet Pepsi. There must be a difference between the content of the two cans. You have studied density and know that an object will float in a liquid if it is less dense than the liquid. Since both cans are identical in volume, they must have different masses. Upon finding their masses on a triple beam balance, you determine that the diet can has less mass than the regular pop can. After thinking about it, you realize that the sugar in the regular soda pop must weigh more than the artificial sweetener in the diet pop. You have come to a reasonable conclusion to explain your observation.

Later at a science center, you see a similar demonstration in which the two cans of Diet Pepsi are placed into two different containers of a clear liquid and one sinks and the other floats. Now you are truly puzzled? What could be going on here? As you listen to the explanation, you realize that one of the containers contained water, but the other contained alcohol, which is less dense than water. Therefore, the Diet Pepsi was denser than the alcohol and sank in it but floated in the water as you had observed earlier. This illustrates the importance of careful observation and the importance of making sure your assumptions are correct. In this context the word “assumption” refers to statements thought to be true upon which we can base our observations and conclusions.

All scientific studies involve some assumptions. If the conclusions we draw are to be accurate, we must be fairly confident that our assumptions are correct. In the example just given, your assumption upon seeing the two containers of liquid at the science center was that both of them contained water. After observing different effects from identical pop cans, you had to rethink your assumptions. If you had been able to examine the liquids, you would have noticed an odor from the container of alcohol and none from the container of water. If you had been able to place your finger in the two liquids and hold it in the air, the more rapid evaporation of the alcohol would have made your finger feel cooler than when dipped in the water. So, with further observations, you can come to the truth about what you saw, and it makes perfectly good sense.

What’s Happening Here?

Here are some brainteasers designed to get you to “think outside the box”; that is, to start without some common assumptions that can lead you to wrong conclusions. Take some time to think these over and then write down your answers.

Situation #1: There is a cabin on the side of a mountain. Three people are inside and they are dead. How did they die?

Situation #2: It is a hot August afternoon. The location is the living room of an old Victorian mansion. The 7-footwindow is open and the curtains are blowing in the breeze generated by a thunderstorm that just passed. On the floor lie the bodies of Bill and Monica. Puddles of water and broken glass surround them. Please close your eyes and picture the scene. Now change the picture. Neither Bill nor Monica has any clothes on. How did they die?

Situation #3: A man is walking down the street, sees a bar and enters. He asks the bartender for a glass of water. The bartender pulls out a gun and points it at him. The man says “Thank you” and leaves the bar. What happened?

Situation #4: A woman leaves home and makes three left turns. She returns home again. On the way, she passed two women with masks. Who were the two women?

Situation #5: A man and his son were rock climbing on a particularly dangerous mountain when they slipped and fell. The man was killed, but the son lived and was rushed to the hospital. The surgeon looked at the young man and declared, “I can’t operate on this boy: he is my son!” How can this be?

Situation #6: Preston and his men searched the frozen tundra for escaped convict Ben Barker. Just as they were about to give up, one of Preston’s men spotted a body. Barker was found lying dead in the snow. There were no tracks leading to or from the body. The cause of death was partially due to the unopened pack on his back. Barker did not die of thirst, hunger, or cold. What was in Barker’s pack that led to his death?

Situation #7: Two train tracks run parallel to each other, except for a short distance where they meet and become one track over a narrow bridge. One morning, a train speeds onto the bridge. Another train coming from the opposite direction also speeds onto the bridge. Neither train can stop on the short bridge, yet there is no collision. How is this possible?

Situation #8: Justin Summers owns a vacation house in northern Ontario which has an A-shaped roof. One side of the roof faces north and the other side faces south. The prevailing winds from the north are usually quite strong. The strange thing is that the stronger the north wind blows, the stronger the resulting updraft on the south side of the roof. Therefore, if a rooster was to lay an egg on the peak of the roof during a strong northerly wind, on which side should the egg fall most of the time?

Situation #9: There is an ancient invention still used in some parts of the world today that allows people to see through walls. What is it?

Situation #10: Sly Hand, the famous magician, claims he can tell the score of any football game before it even starts. Many think he is psychic and possesses supernatural powers. How is it that he can be accurate about the score 100 percent of the time?

Situation #11: It is a stormy, snowy day. There is a dead man inside a shack. There are no windows and the only door is locked from inside. There is no way in or out. The man has a stab wound. There is a puddle of water and blood next to him. How did he die?

The correct responses are found at the end of this lesson. How did you do? If you got over half of them right, you are pretty good at eliminating false assumptions. Some of the assumptions were based on using different definitions of a word or words. Others were based upon replacing unknown information with assumed information, such as that the fish were actually humans because they had human names or that the trains crossed the bridge at the same time when no times were given. Still others are based upon common assumptions, such as all surgeons are men and the score of a game means its final score.

Scientists must be careful that any assumptions they make are not false ones, which is not easy. Sometimes evidence for assumptions is difficult to obtain. Some of the discussions now being held between scientists revolve around the topic of assumptions – are they true or are they subject to error?

Radiometric Dating – Accurate or Flawed?

Radiometric dating is the dating of materials based upon the relative amounts of a radioactive material (isotope) in it compared to the amounts of another isotope, known as the daughter isotope, into which the radioactive material turns during the process of decaying. This decaying is not the same as we would associate with an animal or plant decay.

In order for radiometric dating to be an accurate way of measuring ages of materials we must assume that this break-down of the nucleus occurs with a rate that can be measured. The decay rate is measured by a time known as the half-life. The half-life of a radioactive element is the time it takes for half of the radioactive substance to change into something else. Although the specific time when a nucleus loses either a beta or alpha particle or gamma ray cannot be predicted, scientists have calculated the half-life, and many scientists believe it to be reliable. They believe it has not changed since the beginning of time. This assumption is necessary if this method of dating is to be accepted. Some of the evidence they have for this assumption is that in viewing events that occurred many thousands or millions of years ago can be observed by telescopes because it has taken that long for the light from those events to reach our planet. (Since light travels very fast – 186,000 miles in one second – those cosmic events happened very, very far away from our planet.) In viewing those events, geologists have detected half-lives of the same value as those we use today. Other scientists argue that perhaps the speed of light has changed over the years and therefore, we cannot be sure the half-lives have not changed or the events we observe with the telescope did not happen sooner than most believe. Some believe that tiny particles known as neutrinos may influence the decay rate whereas other scientists say they would have little effect.

The diagram below illustrates how scientists use the radioactive decay of Carbon-14 to date the age of a fossil such as a shell. The shell contains carbonates which have carbon atoms in them. When the animal dies, it no longer takes in carbon and the change from C-14 to the atom N-14 can determine the age of the shell if the half-life is unchanging. Every time a C-14 changes to an N-14 nucleus, a detector signals the event.

Often, rocks are dated by using the amount of a radioactive element and its daughter isotope found in them. The information is used to determine the age of Earth itself. The assumptions that are made include that no material has left or entered the rock once it was formed. Are these assumptions correct? Some scientists feel confident they are, while others cast doubts.

The diagram to the left, illustrates how the amounts of parent (original isotope) and daughter change as a mineral ages. Rocks consist of crystallized minerals. By knowing the half-life of an element in the mineral, scientists can determine how old the rock is. This does involve some assumptions: that the half-life has not changed over time and that the amount of the element in the rock that is being studied has not changed since the formation of the rock.

This can be very confusing to those of us who do not have a background in this subject, but we should not despair. The fact that scientists are debating this is a good thing. Questioning results is essential to maintaining the best grasp of the truth. When assumptions can be shown to be false, then other assumptions must replace those. And then the questioning resumes.

To date, most scientists hold to the accuracy of radiometric dating. That in itself does not mean it is absolutely accurate. However, they do argue that there is a lot of evidence supporting this form of dating. Other methods of studying events in Earth’s history often support the dates derived from radiometric dating. These include (1) studying tree rings to detect age, (2) analyzing ice cores from the Polar Regions, (3) observing layers of sediment under the oceans, and (4) studying the growth of coral reefs. In addition there are more than 40 methods of determining age using this method of radioactive decay and all methods give results that closely agree.

Do Prions Exist?

Where have you heard this word – prion (pronounced pree-ahn and defined below) – before? In our discussion of diseases we used prions for a possible cause of mad cow disease. If you remember, mad cow was thought to have been transmitted to cows from sheep or goats that had a brain-wasting disease known as scrapie. The transmission apparently occurred through feeding cattle feed prepared from the wastes of goat and sheep carcasses, such as bones and hide. The disease for the goats and sheep was known as scrapie because the animals became so tormented that they would scrape against objects until they would scratch all the hair off of their body. Animals infected with this disease suffered dysfunction in the brain due to brain deterioration that left holes in the brain. The brain tissue looked like a sponge or Swiss cheese. Recently in England it was found that a variant of Creutzfeldt-Jakob disease (CJD) was transmitted to humans from infected cows if humans ate meat from these animals. These humans suffered similar symptoms and over 80 people died. Most were between the ages of 19 and 39. Previous to this, CJD was very rare, attacking only one in one million people. It was almost always seen in people over the age of 55, and was the result of contamination from a person who had suffered from the disease during some kind of medical treatment.

Just what is the cause of this brain-destroying disease? To date the culprit seems to be a specific protein known as a prion, but this protein is different from most prions found in the brain. It is folded differently, has all the same parts as the normal protein, but it is shaped differently. It is like the toys called transformers that can assume various shapes even though the parts do not change. A bug changes to a warrior, for example. A mutation is a change in a gene that causes it to behave in an abnormal way. The mutation of the prion in mad cow disease has caused it to change its shape. This prion not only has a different shape but it seems to make other proteins with its same components change their shape to match the shape of the prion. This wrecks havoc in the brain, leading to loss of motor coordination, strange behavior, and eventually death.

The role of normal prions in the brain is not well understood. Recent studies show that all mammals have prions but they can survive without them and suffer no ill effects until late middle age. In studies with mice, some mice were bred without a gene to produce prions. They did not develop scrapie because they had no proteins of the right type to attack. However, they began to develop uncoordinated walking and trembling. Eventually they developed arching backs and collapsed. Another study showed mice that were prion-free survived until much later in life. Other studies have shown that prions may protect Purkinje cells, which keep the brain from aging. The prions seem to help in transmitting signals from cell to cell and although they may not be essential, they seem to fine-tune the brain.

(above)A: normal prion cells in the brain B: abnormal prion cells that cause the brain to malfunction.

If the weirdly-shaped prions are responsible for the scrapie, mad cow, and CJD, then some previous assumptions about disease have to be changed. Until these recent discoveries, it was thought that disease was caused by bacteria, viruses, fungi, or parasites, not by proteins. Also disease was not transmittable from one species to another that was not closely related to it. Sheep and cows are more similar species than humans and cows. This has caused a debate among scientists. Are these weirdly-shaped proteins capable of causing disease even though they do not fit the model? Typically, there has had to be nucleic acid (DNA or RNA) involved providing instructions. The disease is rather complex. Different forms of it have different incubation periods (the time it takes from the time of infection until symptoms are seen), and different strains produce different distributions and patterns in the brain tissue. And in this case, the body produces no antibodies against this invader. To fit the accepted model of a disease there should be nucleic acid present as either DNA or RNA to code the action of this protein but it has yet to be found. When samples of infected tissue have been treated with chemicals, enzymes, or radiation in an effort to destroy nucleic acid and thereby destroy the infective agent, the treatments fail in most cases.

To learn more about Prions, click on Prions PDF File: Prions PDF File.

These results have led some scientists to believe that these diseases are caused by the protein itself when it is in its abnormal folding. In a test tube, this abnormal prion has been able to cause the normal form to change to its abnormal form. The different strains of disease can be explained by different folding of the protein. As stated earlier studies with animals seem to indicate that the type of protein that is present in the animal’s brain determine whether the animal can be infected with a prion disease. Other scientists believe that there is, perhaps, a nucleic acid present in the form of a virus, but it just hasn’t as yet been detected.

The study of prions is far from over. Scientists suspect that other diseases are caused by mutations of prions. Most of these are rare diseases, but two diseases that are becoming more and more common in our society – Alzheimer’s and Parkinson’s diseases – may also be caused by prion malfunctions. The role of the scientist is to study unexplained human behavior by designing experiments to test that behavior, and, also testing to see if they can find evidence of an agent other than the prion protein that causes these diseases. Many scientists will be involved and the same experiment will be done many times to see if the same results are always obtained. Then scientists will examine the data collected to see what valid conclusions can be drawn. It may take years of careful study before agreement can be reached as to how these diseases occur. Then further research will be conducted to see if a cure can be found.

Cancer is a very common disease in the United States and it kills or infects many people each year. It has been studied for many years and although success is being made in its treatment, much still remains to be learned about what causes the cells to turn cancerous, how the cancers grow and spread, and what treatment is best to insure that it does not return. Like the prion diseases, cancer has several forms and it can cause normally “good” cells to malfunction and become a devastating disease.

Unit Conclusion

In science it seems like the more we learn, the more there is to learn. Learning about half-lives allows us to determine the ages of materials if we can be sure that half-lives do not change. How can we know that? What evidence can we find to support unchanging half-lives? Studying diseases, such as mad cow disease, can lead us to unusual observations and perhaps the need to change our current thinking about how information is transferred from one protein to another and how disease can be transmitted from one species to another. Questions are unending, but that is the nature of science. Science is, in part, the huge challenge of attempting to understand the world around us and how it functions. Scientists accept the fact that there are certain fundamental laws that help us understand the occurrence of events. Their job and delight is in studying by setting up careful experiments, collecting data by using all means of observation at their disposal, and then seeing if patterns exist so that logical conclusions can be drawn. Good experiments are very repeatable. That means that others can do them and achieve the same results. The more times an experiment gives the same results, the more reliable the results and the conclusions drawn from them become. Of course, good science requires that the scientist is honest in reporting results and creative in designing a good experiment. Good reasoning skills and an eye for finding errors and misconceptions are necessary traits for everyone who works in science. These are also good skills for everyday life. They help us to make wise decisions throughout life. Developing the skills of a scientist allows us to be better prepared for life in general.

Answers to Quiz on False Assumptions

Situation #1: They were killed in a plane crash. The three people were the pilot, the co-pilot, and the navigator. They crashed in a snowstorm. False assumption: The cabin was a mountain cabin and not the cabin of a jetliner.

Situation #2: They suffocated because the storm winds blew open the window, which knocked the fish bowl off the table, and it crashed to the floor. False assumption: The two dead bodies were human instead of goldfish.

Situation #3: The man who asked for the glass of water had the hiccups. The bartender pulled the gun to scare the hiccups away. False assumption: The bartender wanted to kill the man.

Situation #4: The umpire and the catcher were the two masked women. False assumption: The woman was leaving her house and not home base on a softball field.

Situation #5: The surgeon was the boy’s mother. False assumption: Surgeons are men.

Situation #6: An unopened parachute was in the pack. False assumption: The pack was a back pack and not a parachute pack and that he came to the tundra on foot and not by air.

Situation #7: The trains were crossing the bridge at different times in the morning. False assumption: The two trains arrived at the same time.

Situation #8: Roosters don’t lay eggs. False assumption: That the rooster, being a chicken, was a hen. The many details in the story took your attention away from an obvious mistake.

Situation #9: Windows allow people to see through walls. False assumption: The walls are totally solid. Windows were not invented and are a recent innovation. The phrase “some parts of the world” leads you to believe these are not commonly found.

Situation #10: The score at the beginning of all games is 0 to 0. False assumption: That the score being discussed was the final score.

Situation #11: He stabbed himself with an icicle. False assumption: The water was always in liquid form. Stabbings occur only with knives.