Special relativity / Elementary Tour part 5: Spacetime
"All the world's a stage." - that's how we're used to viewing space: As a stage on which objects are located and where the dramas of their movements and evolution take place. In special relativity, as was mentioned briefly, simultaneity is relative, and so ...
Special relativity / Elementary Tour part 4: The speed of light
On the previous pages, relativity reigned supreme. Although we usually think of lengths and times as absolute, they turned out to be observer-dependent. On this page, the shoe is on the other foot. Ordinarily, we think of velocities as relative, but one of ...
Cosmology / Elementary Tour part 4: A mysterious beginning
From the first millionth of a second on, the big bang models are on fairly safe ground. Standard theories of physics such as the standard model of particle physics tell the researchers how matter behaves under the temperature conditions in question, and the ...
General relativity / Elementary Tour part 2: The cosmic dance
In this new picture, there is no gravitational force that masses exert on other masses. Instead, there are spacetime distortions. Spacetime in the presence of a mass is curved. In flat, empty spacetime, small test particles follow straight lines. However, ...
