How do we know so much about the Universe?

The first views of the workings of the Universe were based on folklore and superstition. The Sun was believed to be a radiating god that rode over the arc of the heavens in a flying chariot. The Earth was the centre of the world. These were not scientific theories, but they explained the world to people.

Part of Copernicus’ drawing of the solar system with the Sun at its centre.

Modern scientific methods started more than two thousand years ago. The ancient Greeks most likely were the first to measure the circumference of the Earth. Nonetheless, the concept of the Earth orbiting around the Sun was discarded and not accepted until long after the publication in 1543 of the work of Polish astronomer Nicolaus Copernicus that showed that the planets orbit the Sun. Though his concept then was revolutionary, Copernicus went no farther than to say that the Sun, not the Earth, was the centre of the Universe. Today, in many cosmological theories, it’s no longer meaningful to think of a centre of the Universe.
All science is based on observation. Scientists observe various phenomena and form theories to explain their observations. The better the observations, the better the theories we can put forth.

Cosmic microwave background radiation is a “fingerprint” from the birth of the Universe. Image taken by NASA’s COBE satellite.

Cosmology – study of the Universe

Cosmology – the study of the Universe – covers almost all sciences, from biology to astrophysics. It is the study of everything known, as well as of the possibility of multiple universes. So it deals with many sciences. One of them is quantum physics, which attempts to explain behaviours at the sub-atomic level, that is, how fundamental particles are formed and behave.

Cosmology consists of many theories. None of them are regarded as indisputable knowledge. No theory is eternally true, because new observations sometimes point to inadequacies in existing theories. Whenever a theory is disproved, a new theory must take its place. And the observations that supported the old theory must also support the new theory.

In other words, our understanding of the Universe is subjective. It is affected by our culture, our religion, and not least by what we have learned from others around us. So theories must be supported by solid, scientific data. Space scientist must have access to precision tools that provide reliable data.

New technologies allow us to observe phenomena that previously may have been unknown or at least difficult to understand. Powerful, space-based observatories including the Hubble Space Telescope, Newton-XMM and Integral are in orbit around the Earth and give us an unobstructed view deeper into space. Some instruments measure the cosmic background radiation and provide a picture of the Universe as it was just after the Big Bang some 13.7 billion years ago.

Scientists learn more about the Universe almost daily, but none dare guess how much we will know five years or a century from now. Most likely, we will have completely new theories on almost everything. The only thing we can be certain about is that we continuously will discover new mysteries.

Is the universe infinite? In any case, it has an endless supply of mysteries.