Stephen is an online writer and former English teacher who is interested in sociology, economics, and literature.
The recent successful launch of the James Watt Space Telescope gives us a powerful tool in our search for life on other planets. James Watt can analyze the atmosphere of exoplanets and detect signs that might indicate life.
These places are so far away - Ross 128b, a rocky exoplanet, is one of the closest that we know of. But still, it's 11 light years away - much too far for one of our probes to get to.
There is life out there. But where? What sort?
Meet the Water Bears
If you have exceptionally good eyesight, you might just be able to see one of the larger tardigrades. But most of them are too small. Pity really, because these little beasts are cute. Cute and everywhere. Water bears, as they are sometimes called, eat plant cells and invertebrates that are even smaller than themselves and they browse in Antarctica, in the deepest of seas, in hot springs, and on top of mountains. They don't seem to worry about their location.
If water bears could choose, I am sure that they would prefer that their environment remained stable and benign. But if things turn nasty, they have evolved a few very neat tricks to cope. They can turn off their metabolism (the term is cryptobiosis) and assume a suspended state that allows them to survive in extremely arid conditions or when there is no oxygen or when it is cold and when there are high levels of radiation.
Ultimately, even extremophiles depend, directly or indirectly, on sunlight.
We can't survive for long without water or food, a tardigrade can cope without either for 30 years. They have survived pressure six times greater than that in our deepest ocean trench and have lived on in a vacuum. Drop some water bears on Venus, Mars, or in the rings of Saturn and pick them up a few years later and they'll revive and carry on as if nothing had happened.
Extremophiles such as tardigrades show us that life is possible under seemingly impossible conditions. Impossible for us, that is. We depend on the sun, without it there would be no crops and, eventually, no us and finally, no extremophiles. Or so it was thought.
In 2008, a bacterium was found living in the Mponeng goldmine in South Africa. Candidatus Desulforudis audaxviator was living in ancient water, 2,8 kilometers below the surface, and formed an ecosystem with just one inhabitant - itself. It didn't depend on sunlight at all. It used a system called radiolysis th find nutrients that react to radiation and had been existing in absolute darkness for millions of years.
There are a few places in our solar system where we might find life - Europa, one of Jupiter's moons, or Titan, which orbits Saturn are both candidates. Mars may have had life once and maybe there is still something there in protected crevices. In these savage environments, anything alive will have to be an extremophile. There's no chance whatsoever that there is another advanced civilization in our solar system. But what about further out?
This discovery gave the relatively new field of Astrobiology a new boost.
Is the Universe Infinite?
The jury is still out. For most f our history, we accepted without question that our Earth was the center of all things in a small system. Then, we slowly, and sometimes reluctantly, became convinced that the earth revolved around the sun and, this being the case, the sun was the true center. This belief was itself replaced when we realized that the sun was a relatively insignificant star in our galaxy.
Then, in 1924, our universe exploded. Edwin Hubble was using the giant telescope at Mount Wilson in California to study hazy patches of light that were clearly not stars. Up to that point, astronomers had believed that these indistinct blobs must be clouds of dust and gas. The one that Hubble focused on was the Andromeda Nebula and he discovered, thanks to the power of this new telescope, that Andromeda wasn't a nebula - it was a separate galaxy. Way back in 1755, Immanuel Kant had put forward the idea that our galaxy might be one of many, but with no way of proving it, this idea remained out on the fringes. But Hubble had now shown that there was at least one more.
Rough estimates suggest that there are around 250 billion stars in our galaxy if we could share them out equally amongst the current human population, we would have over 30 stars each. However, there are more stars to go around in Andromeda, it is estimated to contain 1 trillion.
In the years since Hubble made his startling discovery, advances in technology mean that we can see much more of our universe. Launched in 1990, the aptly-named Hubble Space Telescope has pushed the number up from Edwin's certain two to around 100 billion. This enormous number is likely to be less than half of the true number of galaxies in the observable universe.
If each of these galaxies contains the same number of stars as ours does, the total number is mind-boggling.
So far, in our galaxy, we have discovered over 5,000 exoplanets orbiting other stars. This number increases daily. Most of them have been found through the Kepler Space Telescope, with the addition of the James Watt Space Telescope's capacity, the number will soon go through the roof.
Most astronomers are now sure that most stars have planets. If this is the case, the number of habitats that could have life will be enormous.
Whether the universe is infinite is a matter of debate. But, from our point of view, there are certainly enough stars and planets out there to keep us searching for a very long time.
As Carl Sagan said:
"The universe is a pretty big place. If it's just us, [it] seems like an awful waste of space."
What is Life?
It seems that this should be a pretty easy question to answer but there always seem to be exceptions to any definition. We would all agree that a cat is alive but a sofa is not. But is a virus alive? Some would say yes, but others, point out that a virus can't reproduce outside its host so can't be considered to be a living thing.
Let's settle here for a basic definition. A cell is alive if it can self-replicate, change, and adapt to its environment. By this definition, we can agree that our water bears and our lonely colony of bacteria in the Mponeng mine are alive.
In 1953, two American chemists - Harold C. Urey and Stanley Miller - performed an experiment. They took a mixture of inorganic compounds that were believed to be present on the lifeless early Earth - water, methane, ammonia, and hydrogen. To simulate lightning, they subjected this soup to constant electrical sparks. The end result was the creation of organic molecules from the inorganic ingredients.
A fascinating result, but an organic molecule is not in itself alive. This idea that organic arose from inorganic is called abiogenesis and scientists are still unsure of some of the steps leading to life. They agree that there was no one single event but rather a chain of events of increasing complexity that age birth to the first single-celled, living creatures.
Unfortunately, we can't communicate with a water bear. Intelligence is not part of the definition of life.
How exactly intelligence evolved is a question that is still hotly debated. Perhaps we have it because of our sociable nature and the need to communicate with others in our vulnerable hunter-gatherer groups.
Intelligence will not be a common feature of other life in the universe. Just like here, most living things will be happy to simply exist.
Is Anyone Listening?
Our earliest radio and television transmissions have almost certainly been drowned by radio emissions from our sun. Radar transmissions developed during the Cold War used a different frequency and, by now, are about 60 light years away from Earth. These might be detected but it would require an intelligent being to narrowly focus its attention on our region of space.
Given the sheer size of the universe, it's unlikely that any signal of ours would be found by accident.
Having said that, the Seti institute is actively looking for intelligent life out there. See the link below to find out more about Seti's work.
A Final Word
Life is out there, we can be sure about that. Are there space-faring civilizations building empires in sectors of distant galaxies or is this science fiction.? The universe is 13.7 billion years old. To find intelligent life we need to coincide in space and time. Whole civilizations could have risen and disappeared long before we came on the scene.
We'll keep looking.
Sources and Further Reading
- Tardigrades | American Scientist
These ambling, eight-legged microscopic “bears of the moss” are cute, ubiquitous, all but indestructible and a model organism for education
- The Emergence of Intelligence - Scientific American
Language, foresight and other hallmarks of intelligence are very likely connected through an underlying facility that plans rapid, novel movements
- NASA Astrobiology Institute
- SETI Institute