Help understanding the potential outcome of solving the Unified Theory in modern physics I find myself greatly fascinated by physics and astronomy, though I really do not understand most of it. For example, I avidly watch programs and read books that discuss our current search for a Unified Theory which will unite the major forces (Strong Interactive, Weak Interactive, Electromagnetism on the one side, with Gravitation on the other). I also try to understand a little bit about our work with subatomic particles, the search for the Higgs particle, and our use of tools like the Large Hadron Collider.
Despite this enthusiasm, I find myself asking one major question: What might come of definitively finding a Unified Theory (Theory of Everything)? Most of the material I absorb seem to imply that there are major technological advances from such an accomplishment, but rarely provide examples.
Obviously we cannot predict accurately all of the potential for the outcome of this scientific progression, but I get the impression that physicists and astronomers have a great deal of pending problems that await the solution.
For a layperson, what kinds of advancements and breakthroughs might one realistically expect?
 A: Here is a broad answer as one cannot predict what new discoveries will entail unless they happen. I think then that technological applications will come from any "emergent structures" associated with this theory. So a few cases:


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*No emergent structures. This would be the case if such a unified theory was simply "tidying up" the mathematics of existing theories. This might happen if the unified theory just gave a new (mathematical) perspective on existing known results which managed to (just) unify those theories and no more. This would also imply that existing known physics was very close to the entire physical truth already; but perhaps not expressed in the right way mathematically as yet. So there may be no extra technological consequences.

*Mathematical Improvements. This is similar to the previous case except that the mathematics is calculationally superior in the Unified Theory. This doesnt always happen, but it might then allow us to solve equations that are too complex right now. This probably would translate into more efficient technologies - at least where the maths allowed exploration of physical solutions that are too hard to work with right now. A lay person might not notice these improvements over computational improvements generally, however. On a good day we might get something like High Temperature SuperConductors, maybe as a later spinoff.

*New Fields. These might be at such a scale that any technological advantage would be expensive to undertake. Nuclear Fusion research might be a prototype for this: theoretically available but practically still decades away despite (presumably) understanding the theory. If there were accessible new fields however, there would be technological consequences. History's classic example is Electromagnetism. The definition of "accessible" here would be critical - maybe such fields would only be measurable near large mass objects like Jupiter - eg Higgs field?

*New Spaces. If physics finds new spaces, then they will get explored. In a sense  the Hilbert space of quantum mechanics is a new space which gets explored by examining  unusual shapes (like squeezed light, Bose-Einstein Condensates) that can arise. These have  technological consequences, in fibre optics and elsewhere.
Everything else is Science Fiction speculation, which you can read and wonder...
A: 
The supreme task of the physicist is to arrive at those universal elementary laws from which the cosmos can be built up by pure deduction.
A. Einstein.

There is no (and wasn't) any "practical applications" in the physicist's supreme goal.  
A: It will all depend on what the Theory of Everything will be, no?
We can only look back at the technological progress that appeared once we mastered electromagnetism,  and then quantum mechanics and nuclear physics.
Maxwell unified electricity and magnetism in his theory, in the middle of the nineteenth century. His work in producing a unified model of electromagnetism is one of the greatest advances in physics.It took decades for applications to appear and they are still appearing.
Same can be said about the theoretical formulation of Quantum Mechanics which carried the unification further and gave us from transistors to superconductivity decades after wards.
Ditto for nuclear physics.
So we can only extrapolate, and not predict, that given a rigorous theory of everythinq, unexpected applications will be inevitable.
It is true  that physicists and other researchers are in for the intellectual excitement of frontier research, not for finding applications. Applications are the realm of engineering, once the theory is known.
As for the cost of the LHC, it probably costs less than an airplane carrier, which at a time of peace  is wasted money too. Considering that the world wide web came out of the last accelerator, LEP, as a spin off, and not only this, the money is well invested even so. Already the GRID, a technology of large data transfers and manipulations, is pushing the frontier and will surely find applications in industry in the future.
A: Sean Carroll at the blog Cosmic Variance had an interesting post on this: The laws underlying the physics of everyday life are completely understood. This suggests there are no technologies within the range of energies we can handle on earth which would be transformed by a future 'theory of everything' (super HEP experiments aside). It's a shame because I was looking forwards to those strange rotating devices which would locally nullify gravity!
