...as a science major anything Copernicus is fascinating.
It's unclear exactly what your itinerary includes - in Warsaw, does it include the Copernicus Science Center? You might find it to be of interest.
I've been researching Polish trains for my upcoming visit in April - while not as slick as Trenitalia's for Italy, the Polish train web site is useable once you spend some time with it, and select English as your language:
www.intercity.pl
There appear to be a number of third party sites selling Polish train tickets - you might look at www.polishtrains.eu - it's all in English and the layout is a bit simpler. So as a way to research timetables and fares, it may be easier. Then take your chances, or go to the official site to purchase.
In regard to a daytrip, what concerns me about Torun from Warsaw is that the fast train is still 2:20 - when you factor in getting to/from each station, that would eat more than six hours out of your day, just for transportation.
The suggestion for Lodz may make more sense, as the train ride is only 1:20. Given the history of Lodz, which was a former manufacturing center, you may find the various museums and adaptive reuse of former industrial buildings to be of interest.
But either looks to be an easy train ride from Warsaw, and shouldn't be that challenging even if you don't speak Polish.