[cornelis]

Very well put. I'd offer some minor additions, if you'll let me. We understand that Pasteur's experiment was conducted to test the hypothesis of spontaneous generation. He concluded there was no spontaneity.

Have there been any experiments since then to make his observation obsolete?

[ahayes]

"Spontaneous generation" as Pasteur defined it was known species (flies, mice, etc.) suddenly within a short time frame popping into existence on appropriate substrate. Some of Pasteur's original experimental apparatuses remain at the Pasteur Institute where they still have not spontaneously produced modern bacteria. I believe it is universally accepted that such a thing does not occur.

All of this says nothing about the possibility of abiogenesis as we would define it, being a completely different creature. Using Pasteur's experiments to forbid prebiotic evolution and abiogenesis would be like stubbornly continuing to be puzzled by the massive heat output of the sun--we now know that the heat is due to fusion, which no one before 1920 would have dreamed about.