Listen to this morning's class, "How Does Halakhah Change as Reality Changes?" here.
Follow along with the sources here.
For further learning:
1) Listen to our class on netilat yadayim here.
2) Listen to "Eating Fish with Meat or Dairy" here.
3) Listen to "The Truths of Halakhah (4)," for a fuller discussion of Hazal and science, here.