Whenever there is talk of an infinite Universe it is always about looking out into space - why?
Because that is where you need to go to explore the Universe.
It would be like asking whenever there is talk about Sea Life it is always about looking out into the Oceans.
If indeed the Universe IS infinite this implies that there is no end, or START, so that as well as being infinitely BIG, it must also be infinitely SMALL.
Sounds about right.
This would imply that there would be no end looking down microscopes, as well as up through telescopes and indeed the search for a "fundamental particle" is pointless...
Because the only way to find a true answer it to search for the sake of searching, not for the answer.
As it is less about the "fundamental particle" and more about what else you find along the way.