Let's begin by talking about the scientific method, the process that scientists use for exploring the natural world and making new discoveries. There are five basic steps. First, formulate a question, state the purpose of the experiment. Next, research, investigate and consider what is already known. Then, create a hypothesis, predict the answer to the question. Next, experiment, test the hypothesis. And finally, there's the analysis and conclusion. Did the results of the experiment prove or disprove the hypothesis? During the process, scientists need to collect and record data, information and observations, very carefully. To be considered proof for the hypothesis, the experiment must be repeatable. That means other people can do it and get the same results. Also, the scientists' work usually undergoes a peer review, meaning it is published and other scientists evaluate its accuracy and consistency. When a number of experiments repeatedly confirm a hypothesis, it results in a scientific theory, an idea that is generally accepted as true. Theories, although they are well established by the evidence, are not necessarily permanent. They can be changed, modified and abandoned over time. For example, the Greek astronomer, Ptolemy, had a theory that the Earth is at the center of the solar system. This model was fairly accurate for predicting the positions of the planets, and it was used for over 1,500 years. Then, another astronomer named Copernicus proposed the theory that the Sun is at the center. Later experiments and calculations supported this idea, so the new theory was adopted and the old one was rejected.

Science has dozens of different branches, areas, which can be sorted into the following categories. Physical sciences, life sciences, social sciences, formal sciences, and applied sciences. Let's learn a little bit about each one, starting with the physical sciences. Physics is the study of matter, physical materials, energy, and force. Classical mechanics, for example, predicts the motion of physical objects within the system of forces, such as the Earth's gravity, that's the force that pulls objects down towards the Earth. A few other areas within physics are acoustics, the study of sound, and optics, the study of light. Most physicists also need to have an understanding of thermodynamics, the study of heat, electricity, and magnetism. Chemistry is the study of the properties of matter and how it changes during chemical reactions. Transformations of a substance into one or more different substances. Chemists need to understand atoms, the basic units of chemistry. The different types of atoms are called elements, and they are displayed in the periodic table. Carbon, oxygen, lead, silver, and gold are all examples of elements. Multiple atoms combine to form a molecule. For example, one water molecule includes two hydrogen atoms and one oxygen atom, and that's why we call it H2O.

Earth science is the study of our planet, including fields such as geology, study of the rocky parts of the Earth, oceanography, and hydrology, study of the Earth's water, and atmospheric sciences, study of the atmosphere. The surface of the Earth consists of large sections called plates, and the boundaries between these plates are called faults. Faults are often areas of high geological activity, with earthquakes and volcanoes. Geologists also study erosion, the way wind and water change the soil and rock of the Earth's surface. Erosion can also be caused by human activities such as construction, deforestation, and agriculture. Oceanographers study the ocean's currents, the major directions of flow, as well as marine organisms, plants and animals, and ecosystems, communities of living beings. Atmospheric scientists help predict the weather and keep track of climate change. Nowadays, special attention is being paid to the harmful, bad, effects caused by pollution such as smog and acid rain. Finally, we have astronomy, the study of stars, planets, galaxies, and other objects in outer space. Astronomers use satellites and very powerful telescopes to collect data.

Let's move on to life sciences. Biology is the general term for life science, and it can be divided into human biology, zoology, study of animals, and botany the study of plants. Biologists study cells, which are the fundamental units of life. Cells are organized into tissue, living material, and in animals and humans tissues are organized into organs, such as your heart, lungs, and liver. Another major area in biology is genetics, the study of heredity through DNA. Understanding genetics can help discover treatments for health problems caused by genetic mutations. Mutations are accidental changes in the normal DNA sequence.

Next, we have social sciences. There are many fields of social science, but I'll just mention a few. Anthropology is the study of humanity, including art, culture, and language. Economics studies the production, distribution, and consumption of goods, material items, and services, considering trends of supply, availability of products, and demand, desire from the public. International Relations studies interactions between countries, governments, multinational corporations, and NGOs, non-governmental organizations, and sociology studies social topics, including class, that's economic level, mobility, that's the ability to change in social position, religion, crime, family, and gender issues.

Our next category is formal sciences. Those are based not on observation of the natural world, but instead they focus on the laws of systems based on definitions and rules. Mathematics, statistics, logic, and computer science are a few examples of formal sciences.

Finally, we have applied sciences and engineering. Whereas the other sciences aimed to gain knowledge, applied sciences aimed to apply this knowledge to build or design useful things, or to solve practical problems. For example, a physicist's goal might be to understand the laws of gravity, acceleration, and wind resistance. But an aerospace engineer's goal might be to design a new airplane that flies faster while using less fuel. You've finished Lesson 33. In the quiz, you'll read statements by scientists about their research. Choose the correct type of scientist for the speaker of each statement.

The above is the English listening content about business English courses, speeches, meetings, negotiations, and telephone conversations, collected by Xiao Wu from Qicai.com. I hope you gain something from it!