When we use an analogy that represents the expanding universe with the surface of an expanding balloon, what does the inside of the balloon represent?

hi there if you are asking for conformation that wavelingth is the correct answer is wrong it is the answer is frequency. : )

i hope this you out, have a wonderful day

that tool is called an altimeter which measures your altitude which can be used to tell which atmosphere you are currently in, including the stratosphere.

hope this ! : )