The Big Ideas of Physical Science
What are the basic rules of nature? You can read this book to find out. As a sneak preview, some of these rules are summarized here. You can think of them as the big ideas of physical science. Keep in mind that there are also unknown rules of nature that are waiting to be discovered. In fact, you can take part in the search for these unknown laws if you become a scientist. Even though scientists have already discovered a great deal about the universe, there is still much to learn.
Space and Time
The universe is both very old and very big. The age of the universe is about 13,700,000,000 (13.7 billion) years. The observable universe is about 700,000,000,000,000,000,000,000,000 (700 million billion billion) meters in diameter. The diameter of Earth is “only” 12,700,000 meters. To get an idea of how big this distance is, the diameter of a giant beach ball is about 1 meter.
Matter and Change
A very small amount of the universe is matter. Matter has volume and mass, and on Earth usually takes the form of a solid, liquid, or gas. All matter that you are familiar with, from plants to stars to animals to humans, is made up of building blocks called atoms. Atoms consist of even smaller building blocks called electrons, protons, and neutrons.
Forces and Motion
If you push on something that is sitting still, it starts to move. If you push on something that is already moving, you will change its motion. Forces cause changes in motion. As Figure 4 shows, your world is filled with motion and forces. Calculating these forces can sometimes be very challenging. For example, on a NASA mission to Mars, the Mars Exploration Rover must blast off from Earth on a rocket with enough speed to escape Earth's gravity. The rover must then travel a great distance through space on the rocket and land delicately on a planet that is moving very rapidly around the Sun. The laws of physics allow these movements to be calculated exactly so that the NASA robots get to where scientists want them to go.
Figure 4 The motion of cars on a city street is captured in this timeexposure photograph. Forces govern changes in the motion of each car.
Table of Contents