Telescopes: Peering into the Universe's Past
Telescopes function as tools for observing the Universe's past by collecting light that has traveled across vast distances over extended periods. The principle is that light, despite its speed, takes time to reach Earth, meaning observations inherently show objects as they were when the light was emitted. For instance, sunlight visible on Earth is approximately eight minutes old, and light from Alpha Centauri is over four years old.
Telescopes, especially radio telescopes, are capable of detecting light that has been traveling for billions of years, allowing views almost back to the Universe's inception.
The Power of Radio Telescopes
Radio telescopes offer advantages in observing the distant Universe because radio emissions from faraway objects are often brighter and can travel further than visible light. Supermassive black holes in galaxies produce strong radio signals.
Additionally, the oldest light in the Universe, emitted after the Big Bang, has stretched into radio wavelengths due to the Universe's expansion, making radio telescopes essential for its detection.
Enhancing Sensitivity and Scope
The sensitivity of a telescope, which dictates how far back in time it can see, can be improved by increasing the light-collecting area or by reducing 'noise' from Earth-based interference. Advances in semiconductor technology, cryogenic cooling, amplifiers, and digital signal processing have led to more sensitive radio telescope receivers capable of capturing fainter signals. Furthermore, enhanced digital signal processing hardware and software facilitate quicker and more accurate data collection and processing.
Modern telescopes also benefit from wider views. Traditional radio telescope receivers observed only a small, single point in the sky. However, high-sensitivity multi-beam receivers, like those developed by CSIRO since the 1990s and used in facilities such as China's FAST radio telescope, allow for simultaneous observation of larger sky areas while still probing deep into the Universe's past.
Data processing systems, such as CSIRO's CRACO for the ASKAP radio telescope, combine signals from multiple antennas to create a single, powerful virtual telescope, enabling the simultaneous survey of thousands of sky regions at various distances.
Unlocking the Early Universe
Scientists utilize these advanced capabilities to explore the early Universe, aiming to detect the Cosmic Dawn signal to observe the birth of the first stars. By studying this period, researchers seek to understand how early hydrogen and helium gases evolved into the diverse elements found today, explaining the composition of the current Universe, including Earth.
CSIRO has over 80 years of experience in radio astronomy technology, contributing expertise in analogue and digital systems, timing, signal distribution, and software/data processing. This experience supports global initiatives like the international SKA Observatory's telescopes, which aim to further extend observations into the Universe's past.