What is the most difficult scientific career?

Question

1) on an academic level

2) complexity level

3) practical level

Answer 1

Theoretical physics.

Answer 2

the one for which you don't prepare.

but i'm going to agree with the theoretical physics...especially when it starts getting philisophical

Answer 3

Theoretical physics is sterile, in my opinion.  There hasn't been a new insight in 20 years.  Basically they sit around and rehash theories they have no way of testing.  

1)  Things like fuzzy reasoning and artificial intelligence are much more difficult problems than theoretical physics, since there isn't even a good working model for how to make a machine think.  

2)  Molecular biology.  Dealing with living systems provides many more degrees of freedom than mathematical or theoretical physics.  Imagine trying to do the same experiment, except the results change each time because the organism evolved.  It happens.

3)  Large-scale field-based geophysics.  Same problem as for molecular biology, many many degrees of freedom, coupled with difficulty of collecting data and lack of experimental control.  Suppose you are studying tropical cyclogenesis, each storm is a little different, are the differences you measure significant?  It's hard to tell since you can't reproduce your measurement.  Field work is also complicated by high equipment costs, instrument failure, and generally harsh environments.