Answer:
The word physical has a few different meanings. One, which shows up most often in lay-speak, means bodily (like a physical exam at a Dr's office or physical education in gym class in school). But that's not the meaning of the word used here. Instead, here it actually just means "of or relating to physics" or "characterized or produced by the operations of physics" or "perceptible through the senses and subject to the laws of nature." (source, Merriam Webster's dictionary)