Are We Alone in the Universe?

Professor Brad Gibson of the University of Hull spoke yesterday evening at the Royal Institution in London. He discussed the possibility of there being complex life on other planets in our galaxy, the Milky Way.

I’ve never seen the lecture theatre at the Royal Institution so full of people before, even the balcony- which is usually reserved for late arrivals- was full to the brim. There wasn’t a single empty seat as far as I could tell. Clearly word had gotten around London about the talk.

A bit about Brad:

Brad Gibson is the head of Physics and the Director of the EA Milne Centre for Astrophysics at the University of Hull.Over the last two years he has been responsible for more women entering the field of Physics at Hull University due to his outreach programmes.

He is Hull’s most cited academic.

He studied his MSc and PhD at British Columbia University.

His TED talk on a very similar subject has meant he’s recognised quite often when he travels.

He’s responsible for using determining the expansion of the universe using exploding stars as part of the Hubble Space Telescope Key Project.

For his work, he was awarded the Gruber Prize in Cosmology.

He was the first to identify areas of the Milky Way that are most likely to harbour extra-terrestrial life, which National Geographic named one of the top 10 news stories of the year.

While Gibson’s work on the expansion of the universe is primarily theoretical physics based, he found his way onto the subject of life in other parts of the galaxy through that work. His curiosity peaked and he started asking questions that nobody else had tried to answer before.

“There is no bigger question in science, than the search for extra-terrestrial life” -Stephen Hawking

So, are we alone? It was made very clear when the lecture began that we wouldn’t be getting an answer. Just the tools to make an educated guess of our own. Gibson first wanted to get an idea of what we believed to be the truth to begin with. He asked the audience to close their eyes and raise their hands if they believed there’s life in the universe, if they believed that life was complex, and if they believed that life from other worlds had visited us before.

Considering that the audience was likely made up of those in the scientific community and those who have a personal interest in the subject matter, the results were not surprising:

95% of the audience believed there’s life in the universe.

50% of the audience believed there’s complex life.

2-3% of the audience believed that life from other worlds had visited us before.

This is an interesting contrast to most surveys which usually find that around two-thirds of people believe in the existence of extra-terrestrial life.

This led an audience member to ask why so many people in the world believe we have been visited by extra-terrestrial life before. Gibson gave us five reasons:

1) Meteorites from the surface of Mars

Cast your mind back to 1996 if you’re old enough, and you may remember papers like The Sun and The Daily Mail running headlines announcing, “Life on Mars!” and Bill Clinton announcing holding a press conference about a space rock harbouring bacteria. As is most often the case, the tabloids took a story and blew it completely out of proportion for the sheer shock factor.

Around 15million years ago, 4billion year old material from the surface of Mars was blasted off into space. Some small pieces of this debris made its way to Earth approximately 15,000 years ago, and it was found fairly recently. When scientists chipped a tiny bit of one of the meteorites off and placed it under a microscope, what they saw looked akin to the fossilised remains of nano-bacteria.

Like with all scientific work, the findings were published and the media could then get a hold of and write about them. Despite calls from geologists urgently trying to get across that nothing was proven, and that just because it looked like fossilised life, it didn’t mean it actually was. The story broke and the world’s obsession with Mars began.

Further research of the meteorites has led the scientific community today to say that the debris is not proof of life beyond Earth. There are similar structures and patterns in non-living and even non-organic things on Earth that look very similar to the structures found in the Martian material.

2) Martian sand creatures

Every now and again, the Daily Mail and other similar news outlets publish a story a bit like this:

They claim that there is evidence of life on Mars based on images sent down from the Mars Rover. Interestingly, they usually forget to mention the scale of what’s in the images or to allow for pixilation.

The most likely reason that people can see faces, or images in the patterns in the sand is probably periodolia (the phenomenon caused by our brain’s pattern and facial recognition).

3) The Wow! signal

In 1977, one of the first searches for extra-terrestrial life involved sweeping the sky with a radio telescope on a frequency of 1.4Ghz. The reason we use 1.4Ghz for searches such as this is because of the logic that if intelligent life were trying to reach out and make itself known, it would most likely use the most common frequency of radiation in existence to do so.

One morning, astronomers woke up and saw a massive burst of radio emissions on the read out from the radio telescope (and one wrote Wow! next to it, hence the name). After decades and hundreds of examinations, nothing like this has ever been seen or heard of again since. At the time, even electronic signals or faults could not be blamed for the burst.

A wide array of literature has been produced trying to answer just what the signal was and opinions are still varied. Based on experimentation though, it is mostly believed today that either interference from satellites, comets, or military exercises might have been the cause.

4) Tabby’s Star

Kepler, a NASA satellite which took pictures of stars and measured their brightness in order to help us discover more planets, picked up something rather strange one day. The reason we monitor star brightness is because when a planet passes by, it blocks some of the light from the star and the satellites pick that up.

Usually the light blocked is extremely little, but on this one occasion all the light of the star was blocked. The light then came back and then 20% or so of the light was blocked before the light came back fully again.

This star was called Tabby’s star and the data received from it was unlike anything seen before. Of course, as usual, the media ran away with the story. The Daily Mail in particular claimed with no evidence to back it up that the reason for the strange readings was an alien-built partially-constructed Dyson sphere.

A Dyson sphere is a hypothetical megastructure that completely encompasses a star and captures a large percentage of its power output for a civilisation’s gain. This idea was about as far-fetched as it sounds. In actuality, it’s most likely that comets or a ring of gas and dust were rotating around the star at the time, which would allow for the intermittent dip in light being registered.

5) It’s a hoax

What else can I say on this point except: crop circles, UFO videos, and “aliens created the pyramids!”

The Astrophysical Perspective

According to Gibson, the equation for complex organic life to exist anywhere in the universe is:

LIFE = INGREDIENTS + AN OVEN + COOKING TIME

Which means what exactly? Well let’s break it down, starting with the ingredients.

Carbon

Carbon is needed to build complex molecules. It’s common, and it’s unique in how it loves to bond with anything.

9 parts oxygen for every 5 parts carbon & 6 parts magnesium for every 5 parts silicon

It’s all about balance. If the components are not correctly balanced, life cannot form as it will be too unstable.

Water

Water, unlike anything else in the universe, is a fantastic solvent. Life needs to grab energy and disperse waste in order to survive, so water is a must-have for all organic life.

So those are the ingredients. That’s only 3 things, and there’s an abundance of carbon, oxygen, and hydrogen in the universe. That should mean the galaxy is teeming with life that’s just waiting to be found, right? Well… maybe.

We still need to factor in the rest of the elements from the equation. What’s the oven?

Gibson uses the term “oven” to describe the factors that need to be in play for the ingredients mentioned above to come together and form anything from basic to complex life.

The surface of the planet the life lives on has to have a surface temperature that’s compatible with liquid water.

In order for the planet to be neither too hot nor too cold for water to stay liquid, it has to be in what’s known as the “goldilocks zone” (a certain distance away from a solar system’s sun and main stars). There are only 1- 2 of these planets per solar system.

Protection from high energy cosmic rays.

The Earth has its magnetic field, protecting us from the abundance of damaging radiation in the universe. In our solar system, we know that neither Venus nor Mars have magnetic fields but Mercury does. It’s because of this that there is a NASA mission on the go right now to discover why and whether any form of life could be on Mercury.

A massive moon.

Our moon is particularly huge compared to others that we know of and that makes it very rare. It’s over 1% of the mass of the Earth, and ensures long-term climate stability. Without climate stability, rapid changes in heat and weather could result in the extinction of life on a particular planet.

Those things have sliced the chance of life in our galaxy down an awful lot, but that doesn’t make it impossible by a long shot. All that’s needed is the right kind of planet in the right place with some of the most common chemicals in the universe available to bond on its surface.

But what about the cooking time? Gibson uses this term to mean how long it takes for organic life to become complex and intelligent enough that we could liken it to ourselves.

There are many threats to possibly emerging lifeforms on other planets. The universe has commonly occurring gravitational shocks for example. These shocks don’t affect planets, and we’ve never really noticed them on Earth, but comets are greatly affected. They can be shot out or driven straight into planets which can easily cause a mass extinction (such as the Cretaceous–Paleogene extinction of the dinosaurs).

Every fifty years or so, a supernova (exploding star) occurs. It’s debated how close one has to occur for it to wipe out an entire planet, though the lethal radius is thought to be around 30 light years. This provides any potential life-baring planet with another threat of extinction.

We know from the iron-60 left in our atmosphere that 10 million years ago, the Earth was only 100 light years away from a supernova. If it had been slightly closer, the complex life we are a part of today would not exist.

Even if we can avoid the above threats, natural climate change still means that after a certain period of time (for our planet, there’s around 500 million years left) any complex life must leave their home planet or they will lose the habitable conditions needed for life.

There is also the factor of what happens when complex life has existed for a long period of time. With the war and violence that accompanies multi-celled life, it’s very possible that life can only exist for a certain length of time before it wipes itself out.

It’s seeming less and less likely now that life could exist anywhere. When you look at the evidence, it’s even surprising that it exists here on Earth. Part of Gibson’s work is to run massive computer simulations using all of this data to narrow down the best places in the galaxy for life to possibly develop.

The results of his research show, unsurprisingly that the place our planet is in now is the safest spot of all, which might be why we have yet to find any evidence of life elsewhere in our galaxy.

So, are we alone or not? As I said earlier, we’re not going to have a straight answer to that question because at this point in time there isn’t one. We can however look at the data available from Gibson’s research to try and narrow down the likelihood of life being present elsewhere and make an educated guess based on that.

Out of 100 billion stars:

10% are of the right sort (not too heavy or too light).10% are in the right place.50% have planets.1-10% have rocky planets in a habitable zone.1-10% of those planets have magnetic fields.1-10% have huge stabilizing moons.

That’s pretty positive. There are therefore between 5000 and 500,000 potential civilisations in our galaxy! Great! But if that’s true, where are they and why haven’t we been contacted by them yet?

If each of these civilisations survives for 20,000 years, according to Gibson’s simulations that means that there would be at most only one civilisation in any galaxy at any one time. If that proves to be true, that means that we could be the only planet with complex life in the Milky Way.