Transcript: The scientific method is a way of gaining knowledge about the world we live in. Science starts with curiosity about nature, observing the world, but there is a method to science, a way that distinguishes it from other modes of thought. Science is based upon evidence, upon observations. Scientists take the evidence, and from that they formulate ideas or hypotheses. And eventually when those have been sufficiently tested, the hypotheses become turned into theories about the...

Transcript: The bare bones of the scientific method does not encompass the fact that science is done by people. In the scientific method we have to have someplace for the ideas of luck, serendipity, being in the right place at the right time, persistence, inspiration. How did these fit into the scientific method? The stories of science are full of such ideas. Alexander Fleming, the discoverer of penicillin, itself an accidental discovery, once said “Fortune favors the prepared mind.” ...

Transcript: There’s very little direct evidence in astronomy. In a few cases we’ve been lucky enough to have meteorites falling from space. We’ve even had a few free samples of Mars. But most of the evidence of astronomy is gathered remotely. We’ve sent spacecrafts to most parts of the solar system, and they’ve sent back images and other information of radiation received. We’ve used telescopes to explore distant regions of space. We’ve extended our senses across the electromagnetic...

Transcript: How do we test theories? There are two fundamental ideas. The first is the idea of induction. This was put into place by Francis Bacon, sixteenth century philosopher of science. Induction is the idea that we can generalize from a finite set of observations, or situations, or data, to a much broader range of situations. Science proceeds by induction but always has to recognize that the amount of data is limited and that data has errors attached. So induction is a process that...

Transcript: There are several essential steps in the scientific method. They apply equally to astronomy and all other sciences. The first step is gathering data or observations. In astronomy this is usually not direct evidence. Usually it’s radiation gathered from space. The more observations or data the better. The second process is to analyze the data or look for patterns. Scientists look for patterns in the evidence or observations as a way of understanding how nature works. This...

Transcript: Scientific reasoning is an important part of how science works. You may have your own beliefs or your own faith, and they are your own. They’re unchallengeable. But if you make an assertion in a scientific way, you have to be able to back up that assertion. So when scientists argue about theories and models and data they are using a formal way of arguing about things that can lead to advances in knowledge. A scientist can only make an assertion if it’s backed up by evidence. ...

Transcript: Astronomers have to deal with very large and very small numbers. As we deal with things as low density as the vastness of space and as high density as the center of a black hole, as hot as the first instant after the big band and as cold as intergalactic space, we are dealing with very large and very small numbers. Scientific notation is a short hand for writing very big and very small numbers. For instance, the nearest stars are about 4 or 5 trillion miles or kilometers away....

Transcript; Astronomy spans an enormous range in scales of time as well. The shortest thing we can measure, 10-23 seconds, is the time it takes light to cross a proton. Visible waves of light have a frequency of about 1015 Hertz, which means that one oscillation of light as an electromagnetic wave is 10-15 seconds. In the middle of this huge range are humans; a heartbeat, roughly 1 second. 107 seconds is a year. 1011 seconds is the length of recorded history, and the age of the universe...

Transcript: The study of astronomy contains an enormous range in scales of mass. The lightest thing there is is an electron, 10-30 kilograms. The heaviest atom, Uranium atom, is 10-25 kilograms. The tiny living organisms, a bacterium or a virus, about 10-15 kilograms. Somewhere in the middle of the huge range are human beings with a typical mass of 100 or 102 kilograms. The entire Earth is 1025 kilograms. The sun, 1030 kilograms. And the entire mass of the observable universe,...

Transcript: Astronomy contains an enormous range of scales and length as well. The smallest thing that we can routinely measure is a proton; the diameter is 10-15 meters. The size of a hydrogen atom is 10-10 meters. Somewhere in the middle of the huge range are human beings at about 1 meter in round numbers. The next largest scale we might consider is the size of the solar system or the Earth-Sun distance, 1 Astronomical Units, 1011 meters. A lightyear, a typical distance to a nearby...

Transcript: Another reason that science cannot make statements with absolute certainty is to do with sampling or the limitations of data. Induction as a tool of the scientific method is based on generalizing from a finite set of observations or situations to a broader conclusion. If I had ten people in front of me and I asked which hand each of them wrote with and all ten said that their right hand, would I be justified in concluding that all people are right-handed? You know that the...

Transcript: In science we deal with two fundamentally different types of errors. Random errors are usually associated with limitations in the measuring apparatus. A random error can displace a measurement either to the high or low side of the true value. Random errors are fundamental in science and in astronomy, and their theory was put in place by Carl Friedrich Gauss. Random errors can even apply when we count things. Although you may be able to count the number members in your family...

Transcript: Science is and must be objective. It must be based on observational data and experimentation. The results must be published so that other people can check or confirm or independently measure the same things. Science depends on this, but there is a social element to scientists too. Science is communicated in the public arena, at conferences, and symposia. Theories become popular and then less popular. Thomas Kuhn, the philosopher of science, has referred to the idea of a...

Transcript: Angular measurement is an important part of astronomy. When you want to quote the position of an object on the sky you give it in terms of two different angles. The basic unit of angular measurement is a degree. There are 90 degrees in a right angle and 360 degrees in a circle. The system of angular measurement dates back to Babylonians over 5 thousand years ago. On smaller scales then a degree we divide the degree into 60 units called “minutes of arc” and the minute is...

Transcript: People make many statements in everyday life. Some statements are quantitative and some are qualitative. You might say, “This piece of music is great,” or, “It was cold outside yesterday.” The first statement cannot be quantified. It may be true for you and not true for one of your friends. It’s a purely qualitative statement. The second statement can be quantified, but we need a system of units. Scientists only deal with quantitative statements. Every statement about...

Transcript: Scientists use a system of units based on mass, length, and time. Almost every physical quantity in the world can be reduced to some combination of units of mass, units of length, and units of time. For example area is length times length. Volume is length times length times length. Velocity is a distance or a length divided by a time. Momentum is a mass times a velocity. So many of the things you see in astronomy will be simply reducible to combinations of mass, length, and...

Transcript: Logic is a fundamental tool of the scientific method. In logic we can combine statements that are made in words or in mathematical symbols to produce concrete and predictable results. Logic is one of the ways that science moves forward. The first ideas of logic using words were put together by the Greek philosophers, especially Aristotle. The equivalent mathematical formalism for logic was put together about a hundred years ago by the philosopher Bertrand Russell. The word...

Transcript: Induction is an important tool of the scientific method. In induction a specific statement based on a limited set of data or observations is generalized to form a very broad conclusion. Newton, for example, based on limited measurements of orbits within the solar system, hypothesized that his theory of gravity applied to all orbits inside the solar system and outside the solar system, a very broad generalization called the Universal Law of Gravity. When, subsequently, orbits...

Transcript: Modern science is based on the fundamental idea that we can extend our senses through technology. If all we could learn of the natural world came through our senses of sight, smell, sound, touch, we wouldn’t know much about how the world works. We’d know very little about the microscopic world of the atom, and we’d know very little about the universe beyond the Earth. Physics and astronomy depend completely on the fact that we can extend our senses to detect magnetic and...

Transcript: Because of the huge range of skills and quantities in astronomy, we often use exponential or logarithmic forms when presenting information. Exponential growth and exponential numbers are very different from linear growth and linear numbers. There are three typical forms of exponentials used in science. The first are exponents or powers of 2, that of course is the basis of the binary counting system and the way computers work, exponents or powers of the natural number “e,” 2.7,...

Transcript: There is no science without evidence. When a scientist makes an assertion he must back it up with evidence. The evidence could be evidence that is physical evidence. It could be evidence gathered from telescopes, or microscopes, or other mechanisms we have to extend our senses. But a scientist must always back up what they say with real data. For instance, 200 years ago Jean Batiste Biot in France saw stones that fell from the sky. Nobody thought that stones could fall from...

Transcript: The study of knowledge is called epistemology. There are two fundamental routes or paths for the study of knowledge. One is the idea of empiricism which dates back to Aristotle 25 hundred years ago. In the empirical approach to the method of science everything is based on observation or data. You start by gathering data or observations and then proceed to make a hypothesis which leads to a prediction of other observable phenomena. Then you make more observations to test your...

Transcript: Deduction is a way of combining observations or statements made in science logically. Deduction provides a very strong way of connecting observations with a conclusion. Typically we start with premises and combine them to draw conclusions. For example, if based on measurement I decided that the sun is larger then the Earth and independently that the Earth is larger then the moon, I could deductively conclude that the sun is larger then the moon. In a sense deduction contains...

Transcript: Science starts by looking for patterns in data. Therefore it’s important to understand the distinction between causation and correlation. Scientists believe in causation, the general idea that events have causes. However science starts by looking for patterns in observational data. Typically two quantities may be plotted on a graph against each other. If there’s a correlation, science tries to look for a cause. However it’s not always possible to find a cause, or it’s not...