It's a term that creationists and other science-doubters like to abuse. When we try to explain to them how the Big Bang and evolution can explain the origins and development of life in the universe, their rebuttal is that they are "just theories".
Here is one of my recent articles in a nice, condensed visual form. While baryon asymmetry is an intriguing unsolved problem in modern cosmology, it does not endanger the Big Bang theory in any significant way.
One of the most common headlines I see in popular science articles is "Was Einstein Wrong?". While it is certainly true that relativity is going to be replaced by some more advanced theory of physics at some stage, the basis of Einstein's theory is unlikely to change.
So how do we explain the fact that there is more matter than antimatter in the universe? The fact is that currently, we don't know. This is called the "baryon asymmetry problem" of cosmology.
While it's always healthy to be sceptical about things and to re-examine the evidence supporting your science, it seems a worrying number of people are taking this far too far. The bottom line is that there is a wealth of evidence that supports the Big Bang theory which no other known theory can explain.
Here's another video. I'm often asked how there can be no God if the chances of our planet being habitable are so slim. This is the reason why.
Here's a fascinating thing I learned about recently - how simple the origins of electromagnetism are.
Well, I'm trying my hand at making videos with my trusty whiteboard. Here's a video of me rambling about the nature of light.
It's a phrase you'll often hear if you try and press physicists for answers to the most difficult questions. "What happens at the center of a black hole?", "What happened in the first moments of the Big Bang?" Modern physics is currently not advanced enough to be able to give answers to these questions.