The law seems to only restrict ownership of child porn, which means you cannot legally buy it. So does that mean looking at free child porn on the internet is okay, as long as you don't make any copies for yourself? Not that it'll make a dent in that horrible "business."
No. When you look at any file "on the internet" you're actually looking at a copy you've just downloaded. And the fact that you didn't purchase it has no bearing on whether you own the copy.
This isn't about the technical details of how the internet works. When I open this forum, am I legally
owning a copy of the forum? When I close the window, does this copy of mine continue to exist? Does it continue to be my property, even if it is cached? No, because I make no claims that it is my property.
A pedophile looking at child porn does not "own" the child porn, he is looking at a copy of it on his computer. If he closes the window, then it will probably cache a record of itself on his computer, whether he knows it or not. You can't be held guilty for owning something you did not know was under your possession. It is also impossible to own something without consenting to owning it in the first place.
If you buy a used computer and assume it is clean, and later police find child porn squirreled away on its hard drive, you cannot be held guilty for owning child porn. Even though the child porn was purchased with the property, you did not know it was there, and the person who sold it to you did not disclose the fact that it contained child porn.
If people hack your computer with a virus that makes it display child porn, you cannot be held guilty for owning or looking at child porn. Even though the child porn exists in some form on your computer, you did not consent to having it.
Legally speaking, looking at a webpage for most people* is about the equivalent of borrowing from a library with infinite books.
* (with the exception of more technically-minded individuals who know the deepest nuts and bolts of the internet)