Is There Life Out There?

Is There Life Out There?

It's a question that's been asked for decades by scientists, writers and philosophers alike. Is there alien life out there? Or are we alone in the Universe?

Are We Special?

In 1961 astronomer Frank Drake devised a formula to calculate the probability of advanced life existing beyond Earth. His formula, known as the Drake Equation, factored in the proportion of likely planets around stars that harboured life.

Today most astrophysicists believe that life must exist somewhere in the universe. The number of stars and the planets that likely orbit them is so astronomical that there is simply no way that alien species couldn’t exist somewhere in the universe. Thousands of planets orbiting stars have been discovered in the last 20 years alone. Most of these though are large gaseous planets like Jupiter.

Humanity started to realise that their home planet wasn’t the centre of the universe in the mid-16th century. Copernicus was the first to propound the controversial theory that the Earth orbited the Sun and not the other way round. Decades later the Catholic Church took umbrage, but the theory stuck.

If life does exist somewhere in the outer reaches of space it will probably be carbon-based like that on Earth. Of the four most prevalent elements in the universe, three - carbon, hydrogen and oxygen - are present in 95% of atoms in living organisms. These elements combine easily to form chemical structures with strong bonds, ideal for resilient life forms.

The Search For Alien Life

So if we want to know for sure if life exists elsewhere in the universe, how do we go about searching for it? Well, the usual method is with the use of telescopes which detect radio waves at the low-energy end of the electromagnetic spectrum. Stars and planets emit radio waves and these can be picked up by the radio telescope’s parabolic dish. It’s worth noting that at present we can only search for planets within the Milky Way galaxy. But of course the universe is far larger.

Analysing radio waves from distant planets allows scientists to determine how planets are made. Methane molecules emit a quite different signal than hydrogen molecules, the most common substance in space. High levels of methane or oxygen can indicate the biological processes associated with life.

These are exciting times for alien hunters. Not only are more radio telescopes being built, but more of their time is being allocated to searching for extraterrestrial life.

Are we getting closer to finding life in our galactic next-doors?