Is the Five-Second Rule a Myth?

Most people have heard of the five-second rule. It says if you drop a piece of food, such as a potato chip or an apple on the floor, and if you pick it up right away, within five seconds, it is still clean enough to eat.

Our science class at George Washington Community School decided to test this rule. No, we didn’t use each other to test the rule by eating dropped food to see who would get sick. We used the scientific method to perform an experiment to find our answer.

Experiments should always have a set of variables, the dependent variable and the independent variable. It should also have constants and a control. We used equal amounts of nutrient agar in Petri dishes as a constant. Incubation temperature and time of incubation was a constant. The control was a clean-agar dish that had not been smeared with dropped food. Our independent variable was the time we left the food on the floor – one piece for more than five seconds, the other piece for less than five seconds. The dependent variable was the number of bacterial colonies that grew on the agar after 24 hours.

We decided that we would use bite-size Hershey chocolates as one of our constants. We would simulate the dropping of the candies by rubbing one on the floor for three seconds and another on the floor for seven seconds. If the five-second rule is correct, the hypothesis would be that the candy left on the floor for only three seconds should contain significantly fewer bacteria than the candy left on the floor for seven seconds. However, some of the students decided to state a different hypothesis, that both candies would contain approximately equal numbers of bacteria.

Our procedure, after rubbing the candies on the floor for the specified amount of time, was to rub them on top of nutrient agar in the Petri dish for five seconds each. We then incubated the Petri dishes for 24 hours at about 85 degrees F. At the end of the incubation period, we found that both the five-second dish and the seven-second dish contained considerable numbers of bacterial colonies. We performed three trials, one for each class period. In two trials, the number of colonies was approximately equal. In one trial, the three-second dish actually contained more colonies than the seven-second dish. The control dish contained no bacteria.

We, therefore, concluded that the five-second rule was bogus and simply a myth. The hypothesis stated by students who said that both pieces of candy would contain considerable bacteria proved to be correct. It is not wise to eat any food dropped on the floor for any amount of time.

See a video of one of our students, Emily, performing the experiment on YouTube.

Scientific Method: What Affects a Pendulum's Swing?

Before scientists can find answers to their questions about nature, they first must actually pose the question in a manner that can be answered. They must do research to see if anyone else has already answered that question to their satisfaction. Then they must form a hypothesis, an educated guess, to try to answer the question.

Next, they must design an experiment so that they can test their hypothesis. Designing an experiment includes deciding what materials they will need, what the dependent and independent variables are, what the constants are, and what the control will be.

Variables are the factors in the experiment that will change as the experiment goes on. The independent variable is the thing the experimenter is testing. He decides what the values are going to be in advance. The dependent variable is the factor that changes in response to the independent variable. The constants are factors that do not change. And the control is what the results are compared to.

In the lab we did in class in which we made pendulums, our question was, “What determines the rate at which a pendulum will swing?” Students were asked to formulate a hypothesis that might include any or all of the following variables: length of the string, the amount of weight on the pendulum, or the starting angle (how far the pendulum weight was drawn back). Which one of these variables would affect the rate of swing?

Different students had different hypotheses. Some predicted the rate would be affected only by the length. Others hypothesized that all three factors would affect the rate. And some picked various combinations of two factors.

Our materials included large washers to use as weights, a string measuring 100 cm, a timer, and a meter stick.

We constructed a pendulum by placing a washer on the string and doubling it so that it was 50 cm long. We then set the pendulum in motion and counted the number of swings in one minute. We repeated the procedure for 30 cm and 15 cm lengths of the string. We recorded our results on a table.

In the second part of the experiment, we left the string at 50 cm and timed the pendulum for one minute for each of three weights. We added one washer at the end of each trial. The results were recorded in another table.

Finally, we did two trials in which will kept the weight and length the same, but varied the angle at which the pendulum was pulled back. Again, the results were recorded.

Our conclusions were that the length of the string did affect the rate of swing. We found that the shorter the string, the faster the swing. On the other hand, neither the weight nor the angle affected the rate of swing.

So those students who hypothesized that only the length of the pendulum will affect its rates confirmed their hypothesis. Hypotheses involving other combinations of factors were refuted.

In our experiment involving the length of the pendulum, the length was our independent variable. It is what we controlled. The rate was the dependent variable. Constants included the weight at the end of the pendulum and the angle of the swing.

In the experiment testing for the effect of weight, the weight was the independent variable. Again, the rate was the dependent variable and the constants were the length of the string and angle.

The experiment testing how the angle affected the rate, the angle was the independent variable. The rate was again the dependent variable. Constants were the length of the string and the weight.

Our control was a pendulum with a 50 cm length and a single washer for weight launched from a 45 degree angle.

Students wrote up their results in a report.

The scientific method was followed throughout:

1. We started with our question and a little background information about pendulums.
2. We stated our hypotheses.
3. We designed and then conducted an experiment to test our hypotheses.
4. We came to a conclusion.
5. We wrote up our results for presentation.

Where are the Sunspots?

The sun, like other stars, is a giant ball of extremely hot, roiling, electrically-charged gas called plasma. It is composed almost entirely of the elements hydrogen and helium. Hydrogen is the main source of fuel for the sun. Helium is what is left over after the hydrogen “burns.”

But the sun does not burn by normal chemical means, such as what happens in a fireplace or campfire. The type of burning that everyone is familiar with involves only the electrons of the atom. Electrons spin around the outermost fringes of atoms. Every fire, every explosion, every type of reaction that goes on in the everyday world involves only the outermost electrons. The nucleus of the atom, the central mass that contains protons and neutrons, are not involved.

But in the sun, and in nuclear reactions such as nuclear weapons, the nucleus of the atom gets involved. One type of nuclear reaction, called nuclear fission, happens when a large nucleus splits into two smaller nuclei. This occurs in nuclear power plants or in atomic bombs. It is used to power nuclear submarines. The second type of nuclear reaction releases much more energy. It is called nuclear fusion and is what takes place during a hydrogen bomb explosion, the most powerful weapon ever developed. The sun uses nuclear fusion to produce its energy.

In nuclear fusion, four atoms of hydrogen, which are just single protons, collide at very high speeds and fuse together to form a single atom of helium. The by-product of this reaction is an enormous amount of energy. In the core of the sun, where temperatures exceed 15 million degrees Celsius, nuclear fusion is happening constantly.

The intense heat and radiation produced in the core of the sun takes millions of years to get to the surface, but only eight minutes to reach the earth once it escapes the surface. The surface of the sun looks granular when viewed through a special solar telescope. It is always in motion, like a boiling kettle of water.

The sun also has an intense magnetic field. Sometimes, variations in this magnetic field prevent as much radiation from reaching the surface at localized areas. These small areas on the sun’s surface are a little bit cooler than the surrounding area. So they appear darker. These areas are called sunspots. They are a normal part of the sun’s processes. Although they look small, some sunspots are actually larger than the earth.

The number of sunspots increases and decreases in an 11-year cycle. Every 11 years, the number of sunspots reaches a maximum. A solar maximum occurred around 2001. That means a solar minimum, where sunspots are rare, should have occurred in 2006, and it did. The problem is, by now, there should be a growing number of sunspots again, reaching a maximum by 2012. That doesn’t seem to be happening. We are still in a very deep solar minimum with very few sunspots.

Scientists are not sure why there are so few sunspots or why this solar minimum seems to be lasting much longer than normal. But it has happened before. In 1901 and 1913 there were prolonged solar minimums.

And in the 18th century, there was a very long period of time when sunspots disappeared almost entirely. It is called the Maunder Minimum and it coincided with a period of cooler than average temperatures on earth. Some have called the period the Little Ice Age. It even snowed in June in the middle latitudes, such as central Europe.

It’s too early to tell if we are going into another extended solar minimum on the scale of the Maunder Minimum. But if sunspots don’t return in greater numbers by at least 2010, it could be a sign that an extended solar minimum has begun. Whether that leads to another mini ice age remains to be seen.

The Strength of Science

Sometimes scientists get things wrong. That should come as no surprise to anyone. Science is a process of discovery, analogous to the exploration of new lands by fifteenth-century sailors. Christopher Columbus originally thought he had discovered the East Indies when he landed in the New World.

So when science gets it wrong, that sometimes means the process has to start over or change directions. But that seeming weakness in the scientific process is actually one of its biggest strengths. Science is self-correcting.

Detractors of science, such as those who insist that evolution cannot be true since the theory has been riddled with hoaxes and wrong conclusions, are quick to conclude that these past mistakes have polluted the process, so that most if not all of the conclusions reached by the theory of evolution must be treated with suspicion.

They point to Piltdown man, which was a hoax, and Nebraska man, once thought to be a new species of early human, to justify their argument that all fossil evidence indicating a change from one species to another over time must be erroneous.

But the fact that scientists sometimes draw the wrong conclusions should in no way tarnish the valid scientific conclusions that have withstood the test of time and have been useful in furthering the understanding of how nature works. Everybody makes mistakes. The real test is whether or not those mistakes are eventually recognized and corrected. In science, they always are.

Take Nebraska man as an example. The story is often told that a fossil tooth was found by a farmer in Nebraska who sent it to the American Museum of Natural History. There, a paleontologist identified it as a species of early human. According to the story, it became widely accepted by scientists that this find represented a new species of human being.

In actuality, the paleontologist, Henry Osborn, first identified the tooth as possibly belonging to an ape. It actually turned out to be the tooth of a peccary, a type of wild pig. Other scientists were always skeptical of the claim that it was an ape, much less an early human. Peccary teeth are similar to human teeth, so the mistake was an honest one. But the fact that other scientists did not automatically accept Osborn’s conclusion and then went on to prove he was mistaken shows that although individual scientists might occasionally misinterpret the evidence, the scientific community requires much more validation before accepting that evidence as factual.

It is also true that sometimes scientists, when they believe they have discovered something important, grow fond of their hypotheses. Occasionally, there is even enough data and evidence in support of a hypothesis to actually call it a theory, even if it later has to be modified. In science, a theory is an explanation of a natural phenomenon that is supported by much evidence and has been verified by many scientists.

Take the Superstring Theory, for example. It is the theory in physics that says, in a nutshell, that all the particles in nature that make up the structure of matter can be thought of as tiny vibrating loops or strings of energy. The harmonics of these vibrations determine the type of particle it will be.

Superstring Theory grew out of attempts, which started with Einstein, to merge the two great theories of physics together into a “theory of everything.” Einstein’s General Theory of Relativity dealt very nicely with cosmic phenomena, such as galaxies and black holes. The Quantum Theory was equally adept at describing the very tiny, such as subatomic particles. But they were incompatible with each other.

So scientists worked for decades, trying to merge the two theories. They thought they had succeeded with Superstring Theory. The theory required a 10-dimensional universe and was described using complex mathematics. The problem was that, instead of a single equation, there were at least five equations that worked equally well at describing the universe. This was not an elegant situation. Five equations are too many when you’re looking for one.

A less popular competing theory added an eleventh dimension. But attempts by the small group of scientists supporting this 11-dimensional universe were ignored by the string theorists for more than a decade.

Finally, in a desperate attempt to save their theory, the superstring theorists added an eleventh dimension to their math. Not only did this work, it actually proved that the five earlier equations representing Superstring Theory were actually not separate mathematical descriptions for the universe, but were merely components of the larger eleventh dimension. Mathematically it all fit and has been dubbed Membrane Theory, or M-Theory for short. The one-dimensional strings were stretched into two-dimensional membranes.

It’s all quite esoteric, but the complex mathematics work perfectly well to combine Relativity Theory with Quantum Mechanics. It took more than a decade, but science once again corrected itself to come up with a better explanation of the universe.

This scenario is in stark contrast to those who claim that evolution and the Big Bang didn’t happen because the universe was created in less than a week by a supernatural creator. Called Intelligent Design, their proposal is not a theory because it was not developed using any part of the scientific method. It started with a conclusion, that everything was specially created. And that conclusion can never be modified, regardless of competing evidence.

Think about what would happen if science worked that way. What if Nebraska man had been accepted on face value by all scientists as being true? And what if, even in spite of additional evidence to the contrary, scientists continued to support the notion that Nebraska man was a human ancestor, even to this day? The truth would never be known. If science worked this way, there would be no such thing as new technologies. The world would fall back into the Dark Ages, or would never have emerged from them in the first place.

But science isn’t like that. It is self-correcting and dynamic. That is not a flaw that should be used to prove a weakness in science. Indeed, it is science’s greatest strength.

Poll: How the Public Views Scientists

A new Pew Research Center poll released July 9 is interesting in what it shows about the public’s perceptions about science and scientists compared to the views of scientists themselves on the same topic.

The good news is that the public holds scientists in high esteem, with 70 percent of respondents saying that scientists contribute a lot to the public’s well being. Scientists rank third, below the military (84 percent) and teachers (77 percent).

But even though people tend to view scientists in a favorable light, they still do not concur with them on some hot-button issues that are almost universally agreed upon by scientists. Take climate change, for example. Whereas 84 percent of scientists agree that the earth is getting warmer due to human activity, only 49 percent of the public believe the same thing. And there is a more dramatic schism between scientists and the public on the topic of evolution. Only about a third of the public (32 percent) believe that all living organisms, including humans, evolved by natural means from earlier forms of life, a full 87 percent of scientists believe it.

This brings up an interesting question. What is the source of the beliefs? Scientists tend to shape their beliefs based on things like empirical evidence, observation, and research. The public tends to base its beliefs on information it gets from politicians, the media, from church ministers, or just from word of mouth.

Take the evolution question as an example. A full 97 percent of scientists believe all life on earth evolved, with 87 percent saying that evolution occurred by natural means. Only 32 percent of the public believe evolution occurred by natural means and another 22 percent say evolution occurred, but was guided by a supreme being. Of those who claim a religious affiliation, only 19 percent of Protestants and 33 percent of Catholics believe evolution occurred by natural means, while 60 percent of those claiming no religious affiliation believe evolution occurred naturally.

But that is still a fairly wide disparity between the 60 percent of non-religious lay people and 87 percent of scientists who believe that evolution took place by natural means. The difference can be attributed to how and where the public gets its information. Again, scientists rely on facts and empirical data to form their opinions. The public gets is information from the media and from word of mouth. And there is a flow of information (much of it false) from the religious segment of the public to their non-religious acquaintances.

Even scientists blame the media in part for the public’s lack of good information on scientific topics. According to the survey, 76 percent of scientists say that the media does not do a good job distinguishing between well-founded scientific findings and those that are not. Typically, the media will report on the results of a single, small, and perhaps flawed scientific study as though those results represent a full scientific consensus. That can confuse the public especially when it is bombarded by conflicting results of several studies over a period of years.

Scientists do not accept the results of a single study until other scientists working in the field have confirmed those results with additional studies. Evolution and global warming have been studied by scientists for decades and those studies corroborate each other. But the public hears only two things: Scientists believe that global warming is caused by human activity or that organisms on earth have evolved, and conservative politicians say the evidence is lacking and no conclusions can be drawn. The media report both sides, in an effort to be fair and balanced.

But it really isn’t fair and balanced when comparing almost universal acceptance of an idea by those who have studied it for decades with the ideas of those who are not even in the field and whose agendas are political, religious, or personal. The public still sees equal treatment of both sides in the media and then must choose which side to believe.

Scientists also say that lack of scientific knowledge by the public is a hindrance. The survey indicated that 85 percent of scientists believe the public does not know very much about science. If the public’s science IQ were higher, people would find it easier to ignore media reports on flimsy research and they would be more adept at distinguishing well-founded scientific data from political opinion.

And that’s where a good science education comes in. The U.S. continues to lag behind other developed countries when it comes to educating its children in math and science. New priorities need to be established that will remedy that situation.

In the mean time, it is at least heartening to know that those who agree with scientists on the issues of global warming and evolution tend to be younger and more highly educated. So there may be some hope for the future after all.

GPS: It Knows Where You Are

The advancements in consumer technologies never cease to amaze me. Take the GPS devices for example. These little units have become commonplace over the past few years as their prices have become more affordable to the average American. But what they do, and how they do it, is nothing short of amazing.

Let’s take a quick look at how these little gadgets know exactly where you are and where you’re going.

GPS stands for Global Positioning System. The system relies on a series of satellites. There are 24 of them in operation at all times. They orbit the earth twice per day, circling 12,000 miles above Earth’s surface, each of them in a different orbital path.

Each satellite has on board an atomic clock, accurate down to billionths of a second, and all of the clocks have to be perfectly synchronized. Each GPS device has a quartz clock, which is far less accurate than an atomic clock, but the clock in the GPS unit is synchronized using signals from the orbiting satellites once every second. So you can say that the GPS device has a virtual atomic clock.

Your position is pinpointed using a process known as trilateration. It’s similar to how they determine the epicenter of an earthquake. By measuring the distance to the epicenter from three different locations, you can tell where the earthquake occurred. That’s because if you draw a circle around each seismograph station with the radius of the circle representing the distance to the quake, the circles will intersect at only one place. That’s the epicenter.

So a GPS needs to get signals from at least three different satellites. The distance to each is calculated based on the speed of light and the time it takes for the signal to travel between the satellite and the GPS. A sphere around each satellite with a radius of the distance between it and the GPS will intersect with each other at the exact location of the GPS unit.

The distances are updated once per second, so any movement of the GPS can be calculated. The position and motion of the GPS is then placed as an overlay on a road map. The computer chip inside the GPS makes all these calculations almost instantly.

So, to determine your exact location, the computer chip and software in the GPS has to take into consideration that the GPS is moving and every one of the satellites it is tracking is moving at high speed as they circle the earth. It has to synchronize its internal clock every second using calculations from three satellites. And then it has to place this computed location on a map so that the map moves to keep up with the motion of the GPS. It also then has to select the best routes, calculate your speed, and estimate your time of arrival at your destination.

In addition to all that, the clocks in the satellites have to be updated and synchronized with an earthbound master station to make sure that they are always synchronized with each other. This all has to be done taking into consideration the effects of the atmosphere on radio signals.

It all results in the computation of your location within about five feet of accuracy. How cool is that?

Biology Teachers should Stick to Real Science

Did you take biology in high school? If so, were you taught about the theory of evolution? Were you also taught creationism or intelligent design? It might surprise some of us but according to recent research about a quarter of high school biology students were taught creationism as a valid alternative theory to evolution.

That is having an effect on the way college biology students think about evolution. Those who were exposed to creationism in their high school biology classes were much more likely to believe that creationism could be validated as a real alternative to evolution. Of those who were taught only evolution in high school biology, 75 percent accepted it as scientifically valid.

The problem lies with high school biology teachers. According to the research reported in ScienceDaily, one-fourth of high school biology teachers do not know that it is against the law to teach creationism in science class. And whether they know the legalities or not, it should be clear to them that teaching their own religious beliefs does not equate to teaching a valid scientific alternative.

Some teachers avoid any controversy surrounding evolution and creationism by not teaching either one. Nearly 10 percent of high school science teachers choose not to teach either. Unfortunately, that is cheating students out of the best science education they can get. It is leaving out the most fundamental theory in all of biology. Evolution is the foundation upon which is built most other biological principles, not to mention well-accepted principles of geology and cosmology.

When I was in high school, I did not believe in evolution. I was taught the Creation story in Sunday school and that is what I believed. I was brainwashed as a child and was literally told not to believe what they teach us in high school about evolution.

But when I took biology as a sophomore, my science teacher made a lot of sense. He did mention the bible’s story of Creation, but explained that it did not necessarily contradict evolution theory; it just explained it in different terms.

More importantly, though, the lesson on evolution included an explanation of the evidence for it as well as the mechanisms of how it works. It all seemed very logical to me. I became an evolution convert. I still believed in God and the bible, but I came to realize that perhaps God simply used evolution as his tool of creation.

Since then, I have been on a crusade against the teaching of creationism or its offspring, intelligent design, in the classroom. In the ensuing years since my graduation, state and federal judges across the country, including the Supreme Court, have ruled against teaching creationism as science. Yet some science teachers continue to include it in their lesson plans.

No state has science standards that mandate the teaching of creationism, or even allow for it. Indiana’s state science standards mandate coverage of evolution at almost every level. So why do some teachers ignore the science standards adopted by their state by not including evolution? And why do some continue to include the religious dogma of creationism as though it were an alternative scientific theory?

These teachers are doing a grave disservice to their students who carry their now-skewed understanding of evolution into college. Even biology majors are not immune. The research indicated that many biology majors who were taught creationism in high school still found it an acceptable alternative to evolution when they were freshmen in college.

Science teachers are not scientists. More than 99 percent of biologists agree that evolution is the foundational theory of biology and that it is the best explanation of the diversity of life on earth. But a third of high school biology teachers never studied evolution in college and many of them are not even science majors.

If science students in the United States are to receive a science education equivalent to that in other countries, we must do a better job of educating our science teachers. We need to work with biology teachers and science majors to make sure they have sufficient knowledge about evolution. School administrators must make it clear that teaching religious views in science class is unconstitutional. And teachers need to stick to the standards and the textbooks when teaching students about evolution.

There is already too much encroachment by creationist organizations into the classroom. They build their museums and send literature to science teachers. They are well organized and unrelenting. It doesn’t help that actual science teachers are helping these groups spread their phony science to unwitting high school students.