Are we all alone? – part 2

This is the second part of a post discussing the possibility of intelligent life on other planets. Read part 1 first, if you haven’t already.

In my previous post I focused mainly on the possibility of finding life on other planets, the biggest issue being the enormous distances involved.

Scientists have estimated that there are some 40 billion planets capable of supporting life in the Milky Way galaxy alone, which seems like a big number until you consider how far away we are from any possibly intelligent neighbours. The closest sun-like star is Alpha Centauri, and even if we figured out how to travel at light speed, it would still take over 4 years to get there.

There is some hope though, with planned unmanned missions like Breakthrough Starshot hoping to launch a fleet of tiny spacecraft and propel them towards Alpha Centauri at 15-20% of light speed. If they can make this happen by the planned launch date of 2036, then somewhere between 2060-2070 we may well be getting our first glimpses of life on another planet.

The Canadarm2 robotic arm grapples the SpaceX Dragon CRS-6 cargo spacecraft before attaching it to the International Space Station. Image courtesy of Wikimedia Commons.

I believe that the process of abiogenesis — where non-living matter eventually evolves into organic life – has occurred not just on Earth but on millions, perhaps even billions, of other worlds in our galaxy. But what are the chances of intelligent life evolving, surviving any number of catastrophes, and ultimately becoming a space-faring civilisation? The odds of that occurring are arguably much slimmer, and according to astrophysicist Ethan Siegel, we would just be guessing anyway, since we don’t really have any data. All we know is that it’s better than zero, since life evolved on Earth that way.

So where are they?

Since this isn’t meant to be a scientific blog based on what we know for sure, let’s assume that there are other races out there who, like us, are searching for intelligent life, and developed interstellar travel hundreds or even thousands of years ago.

The Fermi paradox, named after the physicist Enrico Fermi, refers to the apparent contradiction between the high probability of the existence of extraterrestrial civilisations and the apparent lack of scientifically accepted convincing evidence that they do exist.

Whether or not there is convincing evidence that extraterrestrials are visiting us here on planet Earth, there is a significant fraction of the population who believe that UFO’s (Unidentified Flying Objects) are spacecraft piloted by aliens. Most of these phenomena can be explained, but some remain a mystery even after extensive investigation.

One of the more interesting UFO reports is a video of a 2015 encounter between a US military FA-18 Hornet and an unidentified flying vehicle along the USA east coast, referred to as the ‘Go Fast video’. The pilots tracked the object at 25,000 feet above the Atlantic Ocean as it flew away and simultaneously rotated on its axis. No explanation ever emerged.

The ‘Go Fast’ video was one of three pieces of footage released by the US Defense Department’s Advanced Aerospace Threat Identification Program. The first video released, referred to as ‘Gimbal’ (below) shows a number of craft executing manoeuvres that defy physics. A detailed analysis of the footage concludes that it ‘demonstrates flight characteristics unlike anything we know, understand, or can duplicate’.


Apart from UFO’s, there are also the more direct encounters reported as ‘abductions’, where people are essentially kidnapped and subjected to all manner of investigative medical procedures at the hands of aliens. One of the best known of these is the alleged 1975 abduction of Travis Walton, a forestry worker in Snowflake, Arizona.

Walton claims that on November 5, 1975, while riding in a truck with six of his co-workers, they all saw a large saucer shaped object hover above the ground only 35 metres away. After leaving the truck to investigate, Walton was knocked unconscious by a beam of light from the craft, and woke up in hospital-like room being observed by short, bald creatures. He then fought with them until being led away to another room and blacked out again as a clear plastic mask was put over his face. He claims he remembers nothing else until he found himself walking along a highway with the saucer departing above him.

Walton wrote a book about his abduction in 1978 called The Walton Experience, which was then adapted into one of my all-time favourite movies – Fire In The Sky.

The best-known alien abductee would have to be the writer Whitley Strieber, who contends that he was abducted from his cabin in upstate New York on the evening of December 26, 1985 by non-human beings. He wrote about this and related experiences in the book Communion: A True Story, first published in 1987, which was then adapted to make the 1989 film Communion.

Strieber published four additional autobiographies detailing his encounters with the ‘Visitors’ over the next 24 years, and many of the details were revealed only after he underwent regression hypnosis.

There’s no doubt in my mind that alien abductions are a real phenomena, and the first widely publicised case was that of Barney and Betty Hill, who claim they were abducted by extraterrestrials in a rural portion of the state of New Hampshire from September 19 to September 20, 1961.

The Hill’s witnessed a 80-100 feet wide pancake shaped aircraft descend near their car as they were driving along an isolated road. Barney got out to take a closer look, and the craft then moved directly above their car. The Hill’s drove away at high speed but subsequently lost consciousness, waking to find they had travelled 35 miles with only vague memories of the road, arriving home 3 hours later than they should have.

After the incident Betty experienced five nights of vivid dreams where the Hill’s were led on to the spacecraft and subjected to various medical examinations by grey aliens. Further details of the encounter were revealed through hypnosis sessions, and although they were each hypnotised separately, Barney and Betty’s recollections are remarkably similar.

Are these abductions evidence that we are being routinely visited by extraterrestrial beings, and the memories of the encounters repressed by some means? I think it’s a distinct possibility, and perhaps in time, as technology advances, we may be able to capture convincing enough evidence to conclude that we are not alone after all.

Are we all alone? – part 1

In 2015 the physicist Stephen Hawking said:

In an infinite Universe, there must be other life. There is no bigger question. It is time to commit to finding the answer.

The idea that there is not just life, but intelligent life, on other planets is one that has fascinated me since reading Whitley Strieber’s Communion when I was a teenager.

Whether you are a believer like I am or not, the enormity of the universe should be enough to make you doubt that we humans are not a singular anomaly. To get a a sense of this scale, let’s begin with a short astronomy lesson:

Our galaxy is big

Planet Earth is the third amongst eight planets in our solar system (sorry Pluto, you are just a dwarf planet now), all orbiting a star we call the Sun, which scientists estimate was formed some 4.6 billion years ago. Our Sun is in turn one of an estimated 250 billion (+-150 billion) in an island of stars known as the Milky Way galaxy.

The Milky Way is known as a barred spiral galaxy, and it’s an enormous structure, approximately 100 million light years wide, with the Sun located around 25,000 light years from the centre. The image below shows where our sun is located.

Our Sun is located the Orion Arm, or Orion Spur, of the Milky Way galaxy. It’s a minor spiral arm, located between two other arms. Image courtesy of Wikimedia Commons. Updated in 2010 by R. Hurt.

Now that we know there are around 250 billion stars in our ‘local’ galaxy, the next question is how many of those stars are part of solar systems much like ours, with planets orbiting just the right distance from the sun such that life is possible? Scientists refer to this as the Goldilocks zone, which is a range of orbits around a star where a planetary surface is capable of supporting liquid water.

In 2013, astronomers used data collected from the Kepler space mission to estimate that there are around 11 billion Earth-sized planets orbiting in the Goldilocks (habitable) zone of Sun-like stars in the Milky Way galaxy, as well as another 30 billion more orbiting red-dwarf stars (which also have habitable zones like Sun-like stars do).

So that’s around 40 billion planets possibly capable of supporting life in our ‘home’ galaxy, but how about further beyond in other galaxies?

The Universe is even bigger

Astronomers estimate there is an astonishing 10 trillion galaxies in the observable universe. This number was formulated by counting the number of galaxies in a particular region, and then multiplying this up to provide an estimate for the whole universe. Another way to look at it is to hold up a grain of sand to the night sky. The small patch of the sky that it covers contains 10,000 galaxies.

We are getting into really big numbers now, but in short, there are an estimated 1 septillion, that’s 1,000,000,000,000,000,000,000,000 stars in the universe, and around 7.6% of those are class G stars, all of which are thought to have at least one planet. Astronomers estimate that around one quarter of those planets is thought to be in the habitable zone of the local star. Which leaves us with 19,000,000,000,000,000,000,000, or 19 sextillion stars similar to ours with at least one planet similar to Earth. Amazing!

How can we meet?

Hopefully at this point we can agree that it’s likely that intelligent life exists in other solar systems, in our galaxy or in others. The next question I’ve been thinking about is how likely are we to make contact?

The biggest roadblock to finding evidence of extraterrestrial life, let alone making first contact, is the enormous distances involved. Astronomers estimate that the closest sun-like star to us with a high probability of having an earth-like planet in it’s habitable zone is Alpha Centauri, which is 4.37 light years away. That’s 40 trillion kilometres.

Let’s say that we did find an earth-like planet orbiting Alpha Centauri and wanted to send a mission to have a closer look. How long would it take the spacecraft to get there?

The short answer is, a really long time, at least with current technology.

At present the fastest spacecraft so far launched into space are the NASA-Germany Helios probes, which traveled at 250,000 kilometers per hour. At that speed, it would take 18,000 years to reach Alpha Centauri.

The challenge for scientists is to develop the technology so that a spacecraft can travel at a substantial fraction of light speed – at least 10%. At that rate, it would take around 44 years to reach Alpha Centauri, and any data or signals we send back would take an additional 4.37 years.

NASA have plans to launch a mission to Alpha Centauri in 2069, and more recently a project called Breakthrough Starshot announced plans to develop a proof-of-concept fleet of thousands of tiny 1cm sized spacecraft, each with four high-quality cameras and laser communications systems on-board. Using ground-based lasers combined with ‘sails’ on the craft to accelerate them to 15-20% of light speed, they would reach Alpha Centauri in approximately 20 years and beam back high-quality images to Earth. With 100M USD in initial funding already allocated, I think this is the project to watch as they plan to get the first craft launched as soon as 2036.

Hopefully one of these missions will be able to gather conclusive evidence of the existence of extra-terrestrial life in my lifetime, so they’ve got 50 years or so, give or take. Will technology leap forward to allow not just tiny spacecraft to travel at near-light speeds, but actual manned missions? I certainly hope so.

So far I’ve only looked at this from the point of view of us going out there. There is also the subject of them coming here, and maybe that’s something that will happen a lot sooner, or has it already? For more on that, check out part 2.