The Universe as a physics laboratory

By observing light emitted over the past 13.7 billion years, astronomers and astrophysicists can study our cosmic origins.

By observing light emitted over the past 13.7 billion years, astronomers and astrophysicists can study our cosmic origins. Incredibly, 96% of the Universe is unobservable: made of mysterious dark entities that apparently defy both observation and fundamental physics. A phalanx of powerful new telescopes, combined with our ability to detect gravitational radiation, is set to make the next decade significant in the history of astronomy.

Space missions in the solar system hint that liquid water, and perhaps microbiological life, might have existed on other planets closer to home. New insight into the origins of life on Earth is expected from the Rosetta and Dawn missions, which will analyse the primordial material in comets and asteroids. Further such questions will be addressed by the Exobiology on Mars (ExoMars) mission (due for launch in 2018), the BepiColombo mission (due to arrive at Mercury in 2019) and, later on, by instruments aboard Marco Polo and the Europa Jupiter System Mission (EJSM).

NEW WINDOW

Observations across the electromagnetic spectrum have revealed the dynamic nature of the sky, and its variety of extreme events and objects. For instance, by studying the orbits of stars over many years we have found that super-massive black holes reside at the centre of most galaxies — including our own — where they influence the evolution of their host. Black holes and other extreme objects, such as supernovae, drive the cosmic matter cycle by accelerating particles to energies that dwarf man-made efforts, including the Large Hadron Collider, and these too are traced through the electromagnetic radiation they emit.

Astronomers are about to open a new window on the Universe through which to observe systems that do not emit electromagnetic radiation. It is hoped that three large interferometers — GEO-600 in Germany, the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the United States and Virgo in Italy — will discover gravitational waves, which are ripples in space–time produced during extreme events such as the merger of two small, dense stars. Upgrades to these, in combination with the planned Einstein Telescope, the Laser Interferometer Space Antenna (LISA) and radio observations of pulsars, will ensure that key parts of the gravitational-wave spectrum are covered — perhaps picking up gravitational noise from the Big Bang, hundreds of thousands of years before atoms formed and electromagnetic radiation could travel through space.

>> Astronomers are about to open a new window on the Universe through which to observe systems that do not emit electromagnetic radiation.

ASTONISHING PROGRESS

The search for gravitational waves is just one example of the enormous international collaboration required to tackle the toughest problems in modern astronomy and astrophysics: others include the Dutch radio- frequency Low Frequency Array, which will look back to when the first stars formed; the Planck mission, which measures the cosmic microwave background (the oldest electromagnetic radiation); and the Very Large Telescope in Chile, which detects infrared radiation to reveal the hearts of distant galaxies. In the optical and infrared region of the spectrum, the Large Binocular Telescope in Arizona, United States will bring cosmic evolution into view and, by picking up higher frequency X-rays and γ-rays, facilities such as the European Space Agency’s X-ray Multi-Mirror Mission (XMM)–Newton, the High Energy Stereoscopic System (HESS), the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescope, Fermi and eROSITA will hunt for the most energetic processes in the Universe, potentially bringing dark matter into view.

Equally vital is the continued development of, and access to, computing power, which allows us to handle, model and understand data from new experiments. Soon the whole sky will be monitored with unprecedented regularity and resolution. Certainly, the questions of tomorrow will be even more exciting and fascinating than those of today.

The origin, content and structure of the cosmos, as well as its evolution, are key research topics at a number of astronomical institutes in the Max Planck Society. At the Max Planck Institute for Astrophysics, scientists simulated the Universe and followed its evolution in a time-lapse video, comparing the results with actual observations. One important result revealed how the mysterious dark matter is distributed, and how it clumps in the vicinity of galaxies and galaxy clusters (Springel, V. et al. Nature 435, 39, 2005).