Here is the timeline of the largest accelerator ever built to date: http://timeline.web.cern.ch/timelines/The-Large-Hadron-Collider http://timeline.web.cern.ch/

Here is the timeline of the largest accelerator ever built to date: http://timeline.web.cern.ch/timelines/The-Large-Hadron-Collider http://timeline.web.cern.ch/timelines/The-Large-Hadron-Colli... Approved in 1994, completed in 2008, only recently ramped up to full design energy. And that does not include the many years of planning and design which preceded it (it was being worked on already in the 80s). Let's say you are 23 now and contemplating going to grad school to do particle physics. The hypothetical 100 TeV collider is not even at the stage the LHC was in the late 80s, but let's be very optimistic and assume that it will be ready to light up in only 25 years. You'll be 48 by then, and most likely long gone from academia (since there are next to no jobs). That should answer your question.