Special relativity / Elementary Tour: Conclusion
As this brief tour of special relativity has shown, we have to re-think our notions of space and time in Einstein's world. Moving clocks tick at a slower rate, light speed is the same for all (inertial) observers, and lengths and distances depend on who ...
Special relativity / Elementary Tour part 6: E=mc²
Now that the new features of space and time are sufficiently explored, it's time to examine how this affects the way objects move, either freely or when influenced by forces. In other words: How does relativistic mechanics work? This question has led to the ...
Gravitational waves / Elementary tour part 2: Making waves
In our universe, gravitational waves are produced in many different ways. Almost every occasion in which masses are accelerated leads to the generation of travelling space distortions, be it two heavenly bodies orbiting one another or stellar matter ...
General relativity / Elementary Tour part 4: The light side of gravity
For the propagation of light, Einstein's theory makes a clear prediction: Light is deflected by gravity. Just as test particles move on the straightest-possible lines in curved spacetime (i.e. on spacetime geodesics), so does light. The most basic example: ...
General relativity / Elementary Tour part 3: A planet goes astray
The first test of general relativity concerned a situation in which Newton's and Einstein's theories give almost the same result - with a small but crucial difference. The scene: our cosmic backyard, the solar system. The protagonist: Mercury, the planet ...
Special relativity / Elementary Tour part 3: The relativity of space and time
One of the most surprising features of special relativity is that a number of statements and results which we usually think to be absolute turn out to be observer-dependent. In particular, statements about space and time, distances and duration turn out to be ...
Relativity and the Quantum / Elementary Tour part 1: Relativity in the micro-world
Quantum theory and relativity theory are two products of the early 20th century, developed in parallel. Not surprisingly, physicists early on began thinking about the possibility of combining the two. Could one, for instance, formulate a relativistic theory ...
General relativity / Elementary Tour part 1: Einstein’s geometric gravity
The key idea of Einstein's theory of general relativity is that gravity is not an ordinary force, but rather a property of spacetime geometry. The following simplified analogy, which substitutes a two-dimensional surface for four-dimensional spacetime, serves ...
