Simple: The universe expands, but more matter is not created. When the big bang happened, all matter ever or the building blocks of it were released in limited quantities. As Pranceontoast said, you can convert matter, but you can't just create it.
Whether or not the conversion is cyclic for all matter is something that I wrote to sound smart just now, right there.
Not entirely sure if I have my facts straight, but my mighty handsome brain collected some kind of "This is definitely probably the right answer" pertaining to this subject at some point. Whether or not this is it is the question.
:
What if the dogs plucked you up and flew off into the sky on jetpacks?
|
That happened to me this one time.
I
think I have Globophobia; fear of balloons. Some teacher at my elementary school once accosted me for having a balloon in the schoolyard (I was eleven at the oldest) and told this awful story about a baby shower he went to where the baby swallowed a balloon and died.