In this paper, I aim to set out the near certainty that we are far from alone in the universe.
Please bear with me as I try to bring you hard facts. Where certain “facts” are not yet “proven”, they are at least solid theories supported by substantial evidence and respected by most scientists.
Exoplanets - planets not in our solar system (i.e. circling other suns)
Our star, the sun, has nine planets. The question for astronomers has long been whether other stars in the universe also have planets, known as “exoplanets”. Whilst some evidence of this is 100 years old, it wasn’t scientifically proven until 2012. Many more discoveries of exoplanets followed in quick succession.
Thousands of exoplanets have now been found.
It now seems likely that almost all stars have planets circling around them.
This conclusion was first reached in 2013 after evidence of planets was observed in respect of many of the stars close enough to be observed.
Here is a quote from: https://www.space.com/24894-exoplanets-habitable-zone-red-dwarfs.html published in 2014.
- “The new finds imply that virtually all red dwarfs throughout the Milky Way have planets, and at least 25 percent of these stars in the sun's own neighbourhood host habitable-zone "super-Earths," researchers said”
Since 2013 the evidence has grown stronger as more planets have been found. As of April 2019 at least 4,000 exoplanets have been discovered. There are nearly 3,000 more possible candidates.
NASA estimates that since the exoplanet's first discovery, the number of known exoplanets has doubled every 27 months since.
It takes many years to prove the existence of an exoplanet. Scientists have to observe the planet passing around the star. Some of the orbits could be decades-long making detection a slow process. For that reason it could take decades before we have a good estimate as to how many planets circle each star.
At least 656 of the observed stars have more than one planet. Due to today’s limits in telescope technology it is hard to see small earth-sized planets. It is possible that many of the observed stars have multiple planets which we can’t yet observe. Our star has 9 planets. It seems probable that we have only observed the easiest to spot. Probably each star has far more planets than the one or two detected so far.
Are other planets habitable?
So far we have observed some 408 earth-sized planets which are in the “habitable-zone”, meaning that they receive a similar amount of radiation from their sun as we receive on earth. Conditions would be capable of being similar to the planet earth. We don’t yet know if those planets could actually support life, as it would depend on the chemical makeup.
There are more stars in the observable universe than there are grains of sand on on planet earth.
Our Galaxy has an estimated 250 billion stars. Many galaxies have over a trillion stars. In October 2016, an article in Science (based on deep-field images from the Hubble Space Telescope) suggested that there are about 2 trillion galaxies in the observable universe, or about 10 times more galaxies than previously suggested. Putting the two numbers together (250 bln X 200 trillion) suggests there could be 50’000’000’000’000’000’000’000’000 stars in the observable universe. That’s 5 X 10^24 stars. An estimate of the number of grains of sand is ten thousand times lower at 7 X 10^20.
The above numbers are, of course, estimates and the calculations may be out by a factor of 10, or 100 or even 1000s. However the fact remains that we are talking very large numbers of stars. Each star most likely has several planets.
The elements essential for life exist everywhere in space
The elements which were present to allow the formation of life on earth are abundant elements. They exist everywhere in the universe. We don’t know the exact mix, but we know for a fact that the most abundant element is Hydrogen, found in virtually all life forms.
Carbon (C), oxygen (O), hydrogen (H) and nitrogen (N) – make up about 96% of the human body. These elements are known to be among the 7 most common elements in the universe. Countless planets in the habitable zone of stars will have the same elements.
What created life on earth? Was it a unique event?
I won’t elaborate on the devine creation theory, other than to say that if God created life on earth, he probably would not have stopped there. If you are going to grow flowers in your garden, would you stop at ONE seed?
Scientists generally accept that life was created in the brewing mix of elements that swirled in the mud and oceans. Water, methane, ammonia and hydrogen excited by lightening formed into amino acids. As fast as life was created, other elements, like ultra-violet radiation from the sun or the motions of the water would have destroyed it. The chance of survival of any life randomly created would have been practically zero. Fragile microscopic organisms would have been torn apart by the wind rain, ice and chemicals as fast as they came into existence.
The creation of life on earth was thus almost certainly not a single random event. It was created and destroyed trillions of times. Earth was a violent place full of fire and volcanoes, storms and earthquakes. The chance of survival was one in a trillion. Nevertheless trillions of new life forms were created in the rich chemical brew, some of which survived and evolved.
The same thing happened, is happening, and will happen on the trillions of planets which have similar conditions. This is only theory, but it is as logical as saying that if you mix blue and yellow paint in one tin, to get green, the same thing is likely to happen every time you do it.
Is intelligent life rare?
Intelligent life is a common feature of our planet earth. Thousands of creatures and other life-forms on planet earth have some level of intelligence. A reasonable deduction is that intelligence is a possible outcome from the creation of life. Give the prevalence of intelligent creatures, I would argue it is a likely outcome. It just takes a few billion years to evolve.
On any planet where life is created, intelligent life will eventually start to exist. It is a virtual certainty sooner or later. The statistics on planet earth suggest that more than 10% of life on earth has some kind of intelligence.
Given the trillions of galaxies, each containing hundreds of billions and even trillions of stars, most of which are likely to have planets in the habitable zone, life of every kind will be very abundant.
As intelligent life is the norm, that life on distant planets will include intelligent life of all kinds. It is an inevitable conclusion of the facts as we know them.
Given the trillions upon trillions of planets probably with life, there will be both higher and lower intelligent life forms than the human race.
The chance that we are the most intelligent form of life is close to nil. That would be like winning the national lottery hundreds of times in a row.
How long before we have proof of intelligent alien life?
It won’t be long before we receive concrete evidence of intelligent life, in the form of a radio signal or fly-by space ship launched tens of thousands, (or millions), of years ago from some distant planet. There are so many planets out there, many will have evolved long before mankind, and many will have chosen to blast a message to distant galaxies to say “We are here”.
Will we ever meet aliens?
It seems unlikely. At least it is unlikely we will see aliens made of flesh and blood. No flesh and blood creature could ever reach earth alive. At least not with science as we understand it. The nearest star is 4.2 light years away. Even at the fastest theoretical propulsion speeds it would take thousands of years to get here. That would be 1000s of human generations, all the way back to before Christ or the pharaohs were born.
So far, the fastest speed obtained by a rocket launched from earth is 56,000 km/h. That was Deep Space 1. It would take over 81,000 years to traverse the 4.24 light years between Earth and the nearest known exoplanet, Proxima Centauri. To put that time-scale into perspective, that would be over 2,700 human generations. If there is life on that planet, it is very unlikely they will be visiting us.
It is possible that a digital life form could reach us. Computers with artificial intelligence could slumber for tens of thousands of years while they journey through space. If we ever encounter aliens on planet earth, they are likely to be machine based. Make sure you know where the “Off” switch is on the remote control.
What are the chances that other intelligent alien life is alive now?
It all depends on what we mean by “now”? If the radio signal from a star a billion light years away reaches us tomorrow, those aliens will seem very much alive and in the present. Yet the signal was sent a billion years ago, and the alien race which sent it is very likely long since extinct. There are very few stars which are close enough for us to be confident that the senders are still alive by the time we receive their signal.
Radio signal from Alpha Centauri
If a radio signal was sent us we from the nearest star, Alpha-Centauri, it would only take 4.2 years to reach us. In that case we could be fairly sure the senders are still living. However, given the vastness of time, the probability of us getting a signal from Alpha-Centrai is close to zero. Life there either existed billions of years before ours, or it has not yet come into existence. It could be another billion years before they are evolved enough to radio us. We don’t know.
Is anybody out there?
Somewhere out there, in the vastness of space, some alien being is gazing at the stars, maybe looking at our very own Milky-Way and asking himself the question “Is anybody out there?”
We are not alone.