Nothing can be colder than absolute zero, or can it? Arthur Eddington wrestles with the paradox of stellar thermodynamics.
The Infinity Paradox
In an infinite and ageless cosmos, how is it possible that the Universe is cold, dark and dominated by gravity?
Riddle Me This
What happens when one set of evidence contradicts another set of evidence?
Light of Other Days
The weak force is what causes radioactive decay. It’s also what has made life on Earth possible.
Forge of Heaven
The strong force is a complex interaction that holds nuclei of atoms together. It is also the force that lets stars create the elements we see around us.
Dance of the Hag
Electromagnetism can produce a force between charges or magnets, but it is much more than a simple force.
Cradle to Grave
We often speak of gravity as a force. More accurately it is a feature of spacetime. Even more accurately, we don’t know what it is.
The Four Horsemen
There are four fundamental forces in the universe, and each of them plays a crucial role in astrophysics.
We Already Know Quite a Bit
In this series we started with the basic observations of stellar motion in a galaxy, and how that led to the idea of some kind of dark matter. We saw that modified gravity models couldn’t explain things like the Bullet Cluster, while dark matter could. We also saw that dark matter must be something other than the normal matter that makes up you and me. It must be non-baryonic, weakly interacting with light, and make up a goodly portion of galaxies. Then again, our best candidate for dark matter is a hypothetical particle based on a particle physics model that is quite probably wrong.