ARE WE ALONE IN THE UNIVERSE?

Professor Stephen Hawking said that “There is no bigger question in science than the search for extraterrestrial life”.

One day, when I was finishing the editing of my novel “Hallowed Ground”, I went to a talk that not only expanded my mind, but has fixated me ever since.

The subject was “Are we alone in the universe?” and the lecture was given at the Royal Institution, by Professor Brad Gibson, Head of Physics and Mathematics at the University of Hull and Director of the E.A. Milne Centre for Astrophysics. I will try to give you its essence.

Two-thirds of people believe we are not alone in the Universe. Is this wishful thinking or does science bear it out?

There are many radio telescopes across the Earth that have been monitoring signals from outer space for decades now, hoping for evidence of other intelligent lifeforms.

Many of them are monitoring microwave signals at a frequency of 1.4 GHz. Why? Because hydrogen comprises more than 90% of the atoms in the Universe and this frequency is the hallmark of the most common normal matter throughout the cosmos; should an advanced civilisation be interested in announcing their existence, the most common thing everywhere makes the best sense to carry that announcement.

On August 15, 1977, at Ohio State University’s evocatively-named Big Ear radio telescope in the United States, astronomer Jerry Ehman found a signal that appeared to be from an extraterrestrial source, from the direction of the constellation, Sagittarius.  He was so stunned that he circled the reading on the computer printout and wrote the comment Wow! next to it.

The 72-second “Wow! signal” remains the strongest candidate for an alien radio transmission ever detected and no satisfactory explanation for it has been found in the 42 years since.

So how likely is it that there is another civilisation in the Universe capable of emitting the “Wow signal”?

When you look at the composite requirements for life, you realise how unlikely it is. Start with the ingredients. You need carbon but in exactly the right amount, finely balanced with, for example, oxygen. You need the world’s most precious liquid: water. Water is a magical medium for life partly because, unlike other liquids, it freezes from the top, allowing life to continue to thrive under that frozen surface.

A planet needs to have a surface temperature compatible with liquid water which means being at the right distance from a sun - not too close or too far but in the so-called “Goldilocks zone” that’s neither too hot nor too cold. It also needs to have a stable magnetic field to protect it from solar particles. There are 200 moons we know about, but ours is the only one that is big enough, at more than 1% of the Earth’s mass, to stop the Earth from wobbling while it goes around the Sun.

The Earth also sits between the spiral arms in our Galaxy in a relatively quiet zone (called co-rotation), where the arms and our solar system rarely come into contact with one another. Every few hundred million years through, we do pass through a spiral arm, increasing the likelihood that that interaction can shake loose enormous numbers of comets from the Oort Cloud which surrounds us; indeed, this is exactly what happened 65 million years when a comet wiped out 90% of the species on Earth at the time, including the dinosaurs.

If you feed all these factors into a calculation, this is how it plays out….

If you assume 100 billion stars in the Universe…

·      Only 10% are the right sort of stars

·      10% are in the right place in the Galaxy

·      50% have planets

·      10% have rocky planets in the habitable “Goldilocks” zone

·      10% have magnetic fields

·      10% have stabilising moons

This gives you 500,000 potential civilisations if you’re optimistic or perhaps 500 if you are somewhat pessimistic. Sound quite comforting?

Here comes the really chilling part…

The last part of the equation - the “L” factor - is the average length of time a civilisation lasts before it is destroyed or destroys itself.

If each advanced civilisation survives for 20,000 years, there would be, at most, one civilisation alive in the Galaxy at any one time.

Stop to contemplate that…  We might be totally alone in the Milky Way Galaxy.

The “Wow signal” might have never been detected again because it was the last signal sent by a dying civilisation.

That dying civilisation might soon be ours.

The domestication of animals started around 12,500 years ago. The earliest known civilisation was in Sumer in southern Mesopotamia 6,500 years ago.

At our current rate, we could render the planet largely uninhabitable in the next century. Not long after that, another civilisation might pick up our final death signal.

This puts the entire story of “Hallowed Ground” in context for reasons I would love you to find out by reading it.