Maxwell’s theory of electromagnetism contains 4 equations not required by IB.
Definition: An invariant quantity or property of a system remains unchanged as the system undergoes transformations.
One of the important conclusions of Maxwell’s theory of electromagnetism is that the speed of light is invariant in vacuum. This also means that the value for c is independent of any relative motion between source and observer.
The table below summarizes the understandings of 4 renowned physicists on addition close to the speed of light:
| Galileo & Newton | Maxwell & Einstein |
| 0.5csource + clight = 1.5clight | sum of 0.5csource and clight gives clight |
| 0.9csource + clight = 1.9clight | sum of 0.9csource and clight gives clight |
| -0.7csource + clight = 0.3clight | sum of -0.7csource and clight gives clight |