It's been fun, over the past few years, reading accounts of recent developments in physics, astronomy, and cosmology. The universe doesn't look the way we thought it did at the start of the 20th century. There are many galaxies, not just one. The universe is expanding. There doesn't appear to be enough matter--enough ordinary matter--to keep the galaxies together, and the rate at which the universe is expanding appears to be accelerating.
The explanations offered for these last two developments are dark matter and dark energy. In this case, "dark" merely means that we do not have the faintest idea what they really are. We can't detect them. They don't seem to interact with ordinary matter at all. Except they hold galaxies together and expand the universe...
Dark matter and dark energy are hypotheses that explain the observed facts, but so far there's no direct evidence for either. Stuart Clark discusses the problems with this, as well as the other ways in which recent observations, including a high-resolution photograph of the earliest part of the universe we can detect, have produced findings that just don't fit well at all with the current "standard model" in physics.
He thinks we're due for a paradigm shift.
Realizing Earth orbits the sun, not the other way around, was a paradigm shift. Realizing our galaxy isn't the whole universe was a paradigm shift. At some point soon, he thinks, some young scientist somewhere will look at our current standard model, and throw out a basic assumption we all currently take for granted.
His story of the history of physics, astronomy, and cosmology is lively and interesting, and he makes a compelling case for the need for a new paradigm that allows us to explain our current observations of the universe without the current multiple fudge factors needed to make our equations work.
It's a fascinating book.
I bought this audiobook.