>Has theoretical physics advanced enough now that such pen and paper discoveries are all but over
There are plenty of theories generated by theoretical physicists using pen and paper. The problem is that we can't reach the energy scales necessary to test those theories.
>What if a $1 trillion collider is needed to continue making progress?
That's the problem with colliders now. We don't actually know if there are any interesting physics happening at energy scales that are within human reach. Maybe the next 'interesting' threshold can only come about from a galaxy-size collider - so $1 trillion collider isn't going to do squat for you.
>Should we just ... give up on particle physics?
I think we did. There was an article recently about how a next-gen collider to replace the LHC will cost on the order of $100 billion. No one is going to spend that kind of money, so we're done with collider physics for the next few decades.
The same thing happened when the Texas Superconducting Supercollider was cancelled (after >$2 billion spent) but we eventually got LHC. There'll be a winter in high energy physics but eventually the tide will turn.
There are plenty of theories generated by theoretical physicists using pen and paper. The problem is that we can't reach the energy scales necessary to test those theories.
>What if a $1 trillion collider is needed to continue making progress?
That's the problem with colliders now. We don't actually know if there are any interesting physics happening at energy scales that are within human reach. Maybe the next 'interesting' threshold can only come about from a galaxy-size collider - so $1 trillion collider isn't going to do squat for you.
>Should we just ... give up on particle physics?
I think we did. There was an article recently about how a next-gen collider to replace the LHC will cost on the order of $100 billion. No one is going to spend that kind of money, so we're done with collider physics for the next few decades.