Question:
What new information can the new bigger telescopes give us that the current ones can't?
Answer:
Essentially new technology, of course. In fact, the detectors have improved in such a way that it is now possible to make almost simultaneous images in many "colours" in the visible and infrared: so many that we divide that area of the spectrum into thousands of small "slices". In addition, improvements in techniques for correcting atmospheric (adaptive optics) and local/mechanical (active optics) perturbation effects will make using the new large telescopes on Earth's surface almost identical to having them in space. Thus, the limiting effect of the resolution (ability to separate objects that are very distant and, therefore, apparently very close), caused by the atmosphere, is small. Furthermore, as the new large telescopes will be true giants, with fabulous main mirror diameters (e.g. the Extremely Large Telescope - ELT - from ESO, with 42 m; the Giant Magellan Telescope, with 24 m, American; The Thirty Meter Telescope, 30 m, also American), they will capture many more photons (particles of light) than others capture today. In fact, the ELT will capture 16 times more light than the current largest telescope in the world, the GranTeCan, in the Canary Islands, with 10.4 m. But these three giants will only be available starting from 2016