Understanding the energy and matter content of the Universe and its evolution are key goals for the international astronomical community and all extremely large telescope projects. ELTs will bring a wide range of tools to bear on questions relating to the nature of dark energy and the formation and early evolution of galaxies. Natural seeing and ground-layer corrected instruments on ELTs will quantify the assembly of galaxies at modest redshifts, while near-IR diffraction-limited instruments will probe the internal structure of early galaxies and the epoch of first light and reionization.

Cosmological variations in the fine structure constant, $\alpha$, can be probed through precise velocity measurements of metallic absorption lines from intervening gas clouds seen in spectra of distant quasars. Data from the Keck/HIRES instrument support a variation in $\alpha$ of 6 parts per million. Such a variation would have profound implications, possibly providing a window into the extra spatial dimensions required by unified theories such as string/M-theory. However, recent results from VLT/UVES suggest no variation in $\alpha$. The COsmic Dynamics EXperiment (CODEX) spectrograph currently being designed for the ESO OWL telescope (Pasquini et al. 2005) with a resolution high enough to properly resolve even the narrowest of metallic absorption lines, $R \gt 150000$, will achieve a 2-to-3 order-of-magnitude precision increase in $\Delta\alpha/\alpha$. This will rival the precision available from the Oklo natural fission reactor and upcoming satellite-borne atomic clock experiments. Given the vital constraints on fundamental physics possible, the ELT community must consider such a high-resolution optical spectrograph like CODEX.

The recently completed Southern African Large Telescope (SALT) is a low cost, innovative, 10 m class optical telescope, which began limited scientific operations in August 2005, just 5 years after ground-breaking. This paper describes the design and construction of SALT, including the first-light instruments, SALTICAM and the Robert Stobie Spectrograph (RSS). A rigorous systems engineering approach has ensured that SALT was built to specification, on budget, close to the original schedule and using a relatively small project team. The design trade-offs, which include an active spherical primary mirror array and a fixed altitude telescope with a prime focus tracker, although restrictive in comparison to conventional telescopes, have resulted in an affordable 10 m class telescope for South Africa and its ten partners. Coupled with an initial set of two seeing-limited instruments that concentrate on the UV-visible region (320 – 900 nm) and featuring some niche observational capabilities, SALT will have an ability to conduct some unique science. This includes high time resolution studies, for which some initial results have already been obtained. Many of the versatile modes available with the RSS - which is currently being commissioned - are unique and provide unparallelled opportunities for imaging polarimetry and spectropolarimetry. Likewise, Multi-Object Spectroscopy (with slit masks) and imaging spectroscopy with the RSS, the latter using Fabry-Perot étalons and interference filters, will extend the multiplex advantage over resolutions from 300 to 9000 and fields of view of 2 to 8 arcminutes. Future instrumentation plans include an extremely stable, fibre-fed, high resolution échelle spectrograph and a near-IR (to between 1.5 to 1.7 $\mu$m) extension to the RSS. Future development possibilities include phasing the primary mirror and AO. Finally, extrapolations of the SALT/HET designs to ELT proportions remain viable and are surely more affordable than conventional, fully steerable, designs.

Dynamical studies of the centers of galaxies have received a tremendous push forward with the launch of the Hubble Space Telescope. Thanks to its superb resolution power, HST has made it possible not only to convincingly demonstrate the existence of supermassive black holes (SBHs) in galactic nuclei, but also to investigate how SBHs relate to the overall structure of the host galaxy. In spite of this, many questions remain unanswered, for instance, how do scaling relations for SBHs evolve with cosmic time? What is the exact characterization of the local SBH mass function? Are there upper and lower limits to the mass a SBH can attain? The next generation of 30m telescopes will provide the leap in resolution capabilities and collective power which is necessary to address the above questions. I will discuss some of the main science drivers in the field of galaxy dynamics, and the instrument requirements needed to achieve them.

We summarise the science cases for an ELT that were presented in the parallel session on the intergalactic medium, and the open discussion that followed the formal presentations. Observations of the IGM with an ELT provides tremendous potential for dramatic improvements in current programmes in a very wide variety of subjects. These range from fundamental physics (expansion of the Universe, nature of the dark matter, variation of physical constants), cosmology (geometry of the Universe, large-scale structure), reionisation (ionisation state of the IGM at high $z\ge 6$), to more traditional astronomy, such as the interactions between galaxies and the IGM (metal enrichment, galactic winds and other forms of feedback), and the study of the interstellar medium in high $z$ galaxies through molecules. The requirements on ELTs and their instruments for fulfilling this potential are discussed.

Despite recent advances in the study of extra-solar planets the detection of reflected light from planetary atmospheres remains a major goal. For the so-called hot-Jupiters, which are unlikely to be spatially resolved from the central star in the foreseeable future, very high sensitivity measurements are required to detect the reflected signal from the very much larger direct starlight. We describe an optical photo-polarimeter designed to have a polarization sensitivity of at least 1 in $10^6$ and some early observations made in an attempt to detect the polarization signature of $\tau$ Boo b. We discuss the role of such an instrument for the planned ELTs.

A key pursuit of 10-meter-class optical-infrared telescopes is to use deep imaging and spectroscopic surveys to track the evolution of galaxy structure. Future telescopes will continue this quest back to the epoch of the first galaxies, reaching ever fainter structures at ever higher redshifts. Apertures of 20, 30, 50, and 100 meters equipped with the latest in adaptive optics will look out from the world's foremost observing sites, and incrementally improve on point-source sensitivity. But how will they compare for studying extended structures? Scientific avenues that can be pursued with poorer spatial resolution, but require low backgrounds - for example, tracing the formation history of bulges - might allow for tradeoffs between aperture, site, and cost. To explore this parameter space I use a published model of average seeing at any site, develop a simple telescope performance and cost model, and simulate resultant galaxy images over a wide range of absolute brightness, size, bulge fraction, inclination, and redshift. I present a graphical interface to the model which allows side-by-side visual comparison of a given galaxy for any two observatories. This approach is intuitive and flexible, although probably not well suited for detailed analysis of a particular telescope. I compare observatory cost against the relative accuracy of measured galaxy bulge-to-total ratio, and comment on telescope and site requirements.

Spectacular progress in the observational study of rapidly oscillating Ap (roAp) stars has been achieved by considering high time- and spectral-resolution spectroscopy in addition to the classical high-speed photometric measurements. Such observations led to the discovery of a multitude of unexpected phenomena, generally pointing to an extreme vertical chemical non-uniformity of the atmospheres of magnetic CP stars. A detailed analysis of spectroscopic pulsational behaviour allows us to establish a relationship between pulsations and the vertical stratification of the chemical elements. This has become possible with the use of a Very Large Telescope on relatively bright stars. Using Extremely Large Telescopes promises farther heights for asteroseismology.

The scientific capabilities of the James Webb Space Telescope (JWST) fall into four themes. The End of the Dark Ages: First Light and Reionization theme seeks to identify the first luminous sources to form and to determine the ionization history of the universe. The Assembly of Galaxies theme seeks to determine how galaxies and the dark matter, gas, stars, metals, morphological structures, and active nuclei within them evolved from the epoch of reionization to the present. The Birth of Stars and Protoplanetary Systems theme seeks to unravel the birth and early evolution of stars, from infall onto dust-enshrouded protostars, to the genesis of planetary systems. The Planetary Systems and the Origins of Life theme seeks to determine the physical and chemical properties of planetary systems around nearby stars and of our own, and investigate the potential for life in those systems. To enable these four science themes, JWST will be a large (6.5m) cold (50K) telescope launched to the second Earth-Sun Lagrange point early in the next decade. It is the successor to the Hubble Space Telescope, and is a partnership of NASA, ESA and CSA. JWST will have four instruments: The Near-Infrared Camera, the Near-Infrared multi-object Spectrograph, and the Tunable Filter Imager will cover the wavelength range 0.6 to 5 microns, while the Mid-Infrared Instrument will do both imaging and spectroscopy from 5 to 27 microns. The scientific investigations described here define the measurement capabilities of the telescope, but they do not imply that those particular observations will be made. JWST is a facility-class mission, so most of the observing time will be allocated to investigators from the international astronomical community through competitively-selected proposals.

Spectropolarimetry has a broad spectrum of applications, for which there are mostly no substitute observing techniques. They range from the measurement of the strength and structure of magnetic fields via the detection of scattered light from sources obscured by high-density matter or lost in the glare of a nearby bright object to the possibility of individual corrections to the intrinsic luminosities of far-away Type Ia supernovae - and many more. First reconnaissance projects have succeeded with 10m-class telescopes. But the application and extension of the insights gained require substantially larger telescopes. An ELT would in particular enable studies of the formation of structure (AGNs, $\gamma$-ray bursts) in early phases of the universe. At the large distances an ELT will reach, the spatial resolution of point sources, even though only at a very low level, will eventually beat any interferometer. Low cost, the possibility to exploit also not perfectly photometric nights, and the $D^4$ sensitivity of background-limited observations of point sources to telescope diameter are other strong assets.

The ongoing conceptual design activities for the Thirty Meter Telescope (TMT) illustrate many (if not virtually all) of the advanced instrumentation technologies under consideration for future extremely large telescopes. First light capabilities must be based upon credible extrapolations of existing systems and components, while potential upgrades and follow-on systems should explore the full range of advanced and innovative technologies currently proposed for scientific instrumentation and adaptive optics (AO). An affordable technology development program must then be implemented which balances these conflicting objectives.

In this paper, we outline the range of innovative AO component technologies now under discussion for TMT, and describe some of the contracts and studies comprising our AO development program. Components that require advances include piezostack and MEMS deformable mirrors; adaptive secondary mirrors; fast, low noise detectors for both laser- and natural guide star wavefront sensing; guidestar laser sources; and processing electronics for the implementation of AO control algorithms. Instrumentation studies are also underway that investigate issues related to the huge size of seeing-limited instruments; large gratings; integral field spectroscopy; detectors; and advanced techniques for sky subtraction.