Anticipating the Internet: how the predictions of Paul Otlet, H.G. Wells and Vannevar Bush shaped the Digital Information Age

This is an historical research project that investigates predictions of future information technology made by Paul Otlet, H.G. Wells and Vannevar Bush, specifically those described in the Mundaneum, World Brain and Memex respectively. It is carried out by means of an extended review of the relevant Library and Information Science literature and aims to determine the reasons for their predictions, the relationship (if any) between them, and their influence upon the development of the modern-day Internet. After investigating the work of each figure in turn, further investigation is undertaken through a comparative analysis. It concludes that, although there are differences in approach and emphasis between the predictions, each of them was made in reaction to a common problem – the proliferation of published information – and each of them aimed to solve this problem by applying scientific means to improve the free flow of information throughout society, thus improving it for the benefit of all. Furthermore, their ideas stemmed from the same intellectual traditions of positivism and utopianism, and were expressed through technology, that although advanced for its time, was rapidly superseded by the rise of digital computing during the second half of the twentieth century. Finally, although the technology they used to express their predictions is now obsolete, and had little direct influence on the practical workings of the contemporary Internet, the works, concepts and ideas of Otlet, Wells and Bush remain highly relevant in today’s ever-increasingly Digital Age

Design and construction of the IMACS-IFU, a 2000-element integral field unit

The IMACS-IFU is an Integral Field Unit built for the IMACS spectrograph at the Magellan-I-Telescope at Las Campanas Observatory. It consists of two rectangular fields of 5 by 7 arcseconds, separated by roughly one arcminute. With a total number of 2000 spatial elements it is the second largest fiber-lenslet based IFU worldwide, working in a wavelength range between 400 and 900 nm. Due to the equally sized fields classical background subtraction, beam switching and shuffling are possible observation techniques. One particular design challenge was the single, half a metre long curved slit in combination with a non telecentric output. Besides the construction some preliminary results are described.Comment: 10 pages, 7 figures, 1 table. Proceedings for SPIE poster 5492-175 of SPIE Symposium "Astronomical Telescopes and Instrumentation", June 2004, Glasgo

A faint galaxy redshift survey to B=24

Using the multislit LDSS-2 spectrograph on the {\it William Herschel Telescope} we have completed a redshift survey in the magnitude range $22.5<B< 24$ which has produced 73 redshifts representing a 73\% complete sample uniformly-selected from four deep fields at high Galactic latitude. The survey extends out to $z>1$ and includes the highest redshift galaxy ($z=1.108$) yet discovered in a field sample. The median redshift, \zmed=0.46, and form of the redshift distribution constitute compelling evidence against simple luminosity evolution as an explanation of the large excess of faint galaxies ($\simeq\times$2--4 no-evolution) seen in this magnitude range. Rather we identify the excess population as blue objects with $z\sim 0.4$ and $B$\, luminosities similar to local $L^*$ galaxies indicating a dramatic decrease in the density of such objects over the last Hubble time, confirming the trends found in brighter redshift surveys. We also find a marked absence of {\it very} low redshift galaxies ($z<$0.1) at faint limits, severely constraining any significant steepening of the local field galaxy luminosity function at low luminosities.Comment: uuencoded compressed postscript. The preprint are also available at URL http://www.ast.cam.ac.uk/preprint/PrePrint.htm

Spectroscopy of arcs in the rich cluster Abell 963

Spectra are presented for portions of the two arcs observed close to the dominant cD galaxy in the rich cluster Abell 963 (z = 0.206). The spectrum of the northern arc displays a strong emission line at 6600 Å which is seen along the entire arc. The feature cannot be understood unless the redshift is greater than that of the cluster, the most likely interpretation being [O II] 3727 Å at z = 0.771. The southern arc is considerably fainter and its spectrum shows no obvious features. However, new CCD photometry is consistent with a near-constant blue color ( B – R ~ 0.3) along both arcs, supporting the suggestion that they arise from the gravitationally lensed light of a background object. The optical and infrared color is consistent with a spiral galaxy undergoing strong star formation at this redshift. We discuss briefly the implication of this result, and the possible role lensing surveys may play in the study of high-redshift galaxies

Modelling the application of integrated photonic spectrographs to astronomy

One of the well-known problems of producing instruments for Extremely Large Telescopes is that their size (and hence cost) scales rapidly with telescope aperture. To try to break this relation alternative new technologies have been proposed, such as the use of the Integrated Photonic Spectrograph (IPS). Due to their diffraction limited nature the IPS is claimed to defeat the harsh scaling law applying to conventional instruments. The problem with astronomical applications is that unlike conventional photonics, they are not usually fed by diffraction limited sources. This means in order to retain throughput and spatial information the IPS will require multiple Arrayed Waveguide Gratings (AWGs) and a photonic lantern. We investigate the implications of these extra components on the size of the instrument. We also investigate the potential size advantage of using an IPS as opposed to conventional monolithic optics. To do this, we have constructed toy models of IPS and conventional image sliced spectrographs to calculate the relative instrument sizes and their requirements in terms of numbers of detector pixels. Using these models we can quantify the relative size/cost advantage for different types of instrument, by varying different parameters e.g. multiplex gain and spectral resolution. This is accompanied by an assessment of the uncertainties in these predictions, which may prove crucial for the planning of future instrumentation for highly-multiplexed spectroscopy.Comment: 11 pages, 11 figures, SPIE Astronomical Telescopes and Instrumentatio

Coupling starlight into single-mode photonic crystal fiber using a field lens.

We determine the coupling characteristics of a large mode area (LMA) photonic crystal, single-mode fiber when fed with an on-axis field lens used to place an image of the telescope exit pupil at the fiber input. The maximum field of view is found to be approximately the same as that of feeding the fiber directly with the telescope PSF in the image plane. However, the field lens feed can be used to provide a flat, maximised coupling response over the entire visible-NIR which is not possible using either the highly wavelength dependent direct feed coupling to the LMA fiber or the attenuation spectrum limited step index fiber cases