A New Era of Telescopes

The first telescopes were built in the 17th century, and Galileo Galilei used them to study the sky. Their operation was based on simple lens systems. For today’s astronomers, however, the images they produced would appear blurry and the magnification far too low. Modern astronomical observations require increasingly sophisticated instruments and research methods, often operating at high energies. This new era of telescopes opens fresh windows onto the Universe.

One such modern instrument is the H.E.S.S. telescope (High Energy Stereoscopic System) located in Namibia. It is actually an array of four telescopes, designed to observe the Universe at ultra-high energies. The central H.E.S.S. telescope is currently the largest single optical telescope on Earth. Scientists from the Astronomical Observatory of the University of Warsaw have been participating in observations with H.E.S.S. since 2008. Among the most significant results are surveys of the Milky Way disk.

H.E.S.S. has also contributed to testing quantum gravity theories. Physicists had predicted that space might be quantized, composed of tiny cells about the size of the Planck length—the smallest fundamental unit used in physics. Such a quantized structure would subtly affect how light travels: radiation with shorter wavelengths would move more slowly. Though the effect is extremely subtle, observations with H.E.S.S. allow scientists to test this hypothesis. Observations of the blazar PKS2155-304, the nucleus of a distant, rapidly variable galaxy, confirmed that the quantum structure of space must be much smaller than the Planck length!Many telescopes, however, remain in the planning stage. The Cherenkov Telescope Array (CTA) is a project that will enable a better understanding of the cosmos under the most extreme conditions. It represents a new generation of gamma-ray astronomy, pushing the boundaries of what we can learn about the Universe. Its sensitivity will be 5 to 10 times higher than current observatories, such as H.E.S.S., MAGIC, or VERITAS. The energy range covered will be unprecedentedly broad, allowing a more complete understanding of the physical processes responsible for gamma-ray emission. With CTA, scientists hope to address fundamental questions about the nature of dark matter, the sources of cosmic rays, and the mechanisms powering the most energetic explosions in the Universe.