When we hear the word “relativity,” we often think it means that everything is relative to something else, like your perspective, age, or where you are in space and time. But actually, many things in our world are not relative. For instance, George Washington was the first president of the United States, and World War I happened before the movie Star Wars was made. These are facts that don’t change no matter how you look at them.
Some things are indeed relative. For example, whether an apple is on your left or my right depends on our perspectives. Similarly, whether 50°F feels hot or cold can vary from person to person. In science, especially in physics, things that change based on perspective aren’t considered fundamental. Scientists are more interested in things that are absolute—those that remain constant no matter how you look at them.
For a long time, scientists believed that distances in space and intervals of time were absolute. However, Albert Einstein’s special theory of relativity changed that view. He showed that distances in space and time are actually relative—they change depending on how fast you’re moving. But Einstein also identified some quantities that are absolute, like the distance between two events in spacetime, the energy-momentum of an object, and the speed of light.
Einstein’s general theory of relativity further expanded on these ideas. It revealed that neither acceleration nor gravitational force is absolute. Depending on your perspective and path through spacetime, accelerations can transform into gravitational fields and vice versa. The more fundamental absolute quantity here is the curvature of spacetime, which can be thought of as an “absolute” form of gravity.
At their core, both special and general relativity are about identifying what’s real, regardless of perspective. If everything were relative, science wouldn’t exist because there would be no universal truths or laws. Science thrives because there are absolutes in the universe—truths that remain constant no matter who observes them. In essence, science is about discovering these truths that hold true even without the scientist.
So, while relativity might sound like everything is up for debate, it’s actually about finding the constants that define our universe. And that’s what makes science so powerful and fascinating!
Pair up with a classmate and role-play a conversation between Albert Einstein and a modern-day physicist. Discuss the concepts of absolute and relative quantities in physics. Focus on how Einstein’s theories changed the understanding of space and time. Present your dialogue to the class.
Create a spacetime diagram to illustrate an event from your daily life. Plot the time and space coordinates and show how these might change from different perspectives. Use this diagram to explain the concept of relativity to a peer.
Conduct a simple experiment to understand the constancy of the speed of light. Use a flashlight and a mirror to measure the time it takes for light to reflect back. Discuss why the speed of light is considered an absolute constant in the universe.
Use a large piece of fabric and some weights to simulate the curvature of spacetime. Place a heavy object in the center to represent a massive body like a planet. Roll smaller objects around it to observe how they move. Discuss how this relates to Einstein’s general theory of relativity.
Participate in a class debate on the importance of absolute truths in science. Prepare arguments for why absolutes are essential for scientific progress and how they differ from relative perspectives. Reflect on how this understanding impacts scientific inquiry.
Relativity – A theory in physics developed by Albert Einstein, which states that the laws of physics are the same for all non-accelerating observers and that the speed of light is constant regardless of the motion of the observer or light source. – According to the theory of relativity, time can appear to move slower or faster depending on the relative speed of the observer.
Perspective – A particular attitude or way of viewing something; in physics, it can refer to the frame of reference from which observations are made. – From the perspective of an observer moving at high speed, the length of an object appears contracted due to relativistic effects.
Absolute – In physics, a concept or quantity that is universally constant and not dependent on any external factors or conditions. – The speed of light in a vacuum is considered an absolute constant in the universe.
Spacetime – A four-dimensional continuum in which all events occur, integrating the three dimensions of space with the dimension of time. – In Einstein’s theory of general relativity, gravity is described as the curvature of spacetime caused by mass.
Gravity – A natural phenomenon by which all things with mass or energy are brought toward one another, including planets, stars, and galaxies. – The force of gravity keeps the planets in orbit around the sun.
Einstein – A theoretical physicist who developed the theory of relativity, one of the two pillars of modern physics. – Einstein’s equation, E=mc², shows the equivalence of mass and energy.
Science – The systematic study of the structure and behavior of the physical and natural world through observation and experiment. – Physics is a branch of science that explores fundamental concepts such as energy, force, and motion.
Constants – Quantities in physics that remain unchanged under specified conditions and are fundamental to the laws of nature. – The gravitational constant is one of the key constants used to calculate the force of gravity between two masses.
Energy – The capacity to do work or produce change, existing in various forms such as kinetic, potential, thermal, and more. – In a closed system, the total energy remains constant, illustrating the principle of conservation of energy.
Motion – The change in position of an object over time relative to a reference point. – Newton’s laws of motion describe how forces affect the movement of objects.
