The degradation of photographic film over time is basically chemical reactions. Any chemical reaction can be sped up or slowed down by various means.
Heat - chemical reactions go faster in higher temperatures, and slower in lower temperatures.
Catalysts - the presence of a catalyst will speed up a reaction
Film speed - in the case of photographic emulsions, generally speaking faster film will degrade quicker. Delta 3200 and TMZ will degrade significantly faster than FP4+ or Fomapan 100 for example.
In the case of film there are other factors such as humidity. Radiation and cosmic rays have been mentioned already. The bulk of the radiation will be shielded by your fridge/freezer and the unless you're in a very high radon area or are also storing radioisotopes in your fridge it is probably of no practical consequence. It will take many decades for your film to be fogged by background radiation or cosmic rays.
With B&W film, freezing does effectively stop the chemical reactions. Frozen B&W film has been known to last 30,40 even 50 years and come out fresh. With all films, try and keep in the original canister or foil package without opening these. With roll film that has backing paper, this is doubly important as moisture getting inbetween the backing paper and film, or just on the backing paper, can wreak havoc.
Film can even react with air, or gases in the air may act as mild catalysts to speed up the reaction, so again, keep the film in the foil packs or plastic tubs. Don't be tempted to have a look at it. It is good practise to put your films in zip-lock or press shut bags. It's fine to fill the bag with multiple films, try and squeeze the air out of the bag before shutting it.
When the time comes to defrost, let the chosen films thaw fully before opening them and loading them into a camera. At least an hour, but I tend to thaw them the night before a trip. This is extra important for roll films with backing paper for the reasons mentioned above. Note that film is not meat, it is perfectly fine to freeze, thaw, refreeze, thaw, refreeze in cases where you don't get round to using it.
I know there are people here who are using 30+ year old stashes of frozen film. I've personally frozen film for 15-20 years and it came out indistinguishable from fresh. For the sake of caution, I probably wouldn't freeze HP5+ for 40 years and then push it ti 6400ISO. But that's why I freeze my Delta 3200 and TMZ.
General rule, but YMMV, is that B&W film can effectively last a human lifetime this way....C41 colour negative 20 years or so....E6 slide film 10 years. But you'll always find anecdotal evidence of people who found their stash of Tri-X went bad after 10 years or who found a 30 year old roll of Ektachrome in the fridge and it came out fine.