What are the most puzzling questions for you to answer? Some of the most fundamental questions in science are- ‘How did everything start?' ‘Where do we come from?', ‘Are we alone in the Universe?', ‘Will we find other places to live in our Universe?' Questions like these have shaped our understanding of the Universe. While such questions are challenging to answer, we have come a long way in knowing ourselves and the world around us a little better.

 

How did our journey begin?

The story of anything living can only begin with the beginning of the Universe. This happened around 13.7 billion years ago with an event called the ‘Big Bang'. At that time, the Universe was no larger than an atom. The stars, that we see twinkling at night, appeared only 250 to 350 million years after the Big Bang. These stars are the factories that produce most of the elements that we read about in our high school Chemistry classes. Everything that we see around us is made of different combinations of these elements.

Earth was formed about 9.2 billion years after the Big Bang and developed conditions to support life. It was rocky, just at the right distance from Sun, had liquid water, and had the perfect ingredients needed for life. If life is a soup then can this soup be prepared from any ingredient at hand?

It turns out that out of the ninety-eight naturally made elements, life essentially requires only six. These are hydrogen, carbon, nitrogen, oxygen, phosphorous, and sulfur. These elements were produced in the stars. In fact, the elements that we and everything living around us are made up of were once synthesized in the cores of the stars. Even though we all have wondered

about them since our nursery classes, these stars are truly our ancestors. As Deamer states:

 

As living organisms, we are not in any way separate from the rest of the universe. Instead, we simply borrow a tiny fraction of its atoms for a few years and incorporate them into the patterns of

life.

 

Once the elements essential for life were produced in the cosmos, the challenge was to assemble them. Only some particular combinations of these elements can result in biomolecules which are the ‘molecules of life'. To understand this better take for example the English letters w, o, and n which you can combine to make six words. Out of the six words, only three words – now, own, and won will be meaningful and nwo, onw, and wno will be gibberish.

Amino acids, monosaccharides, fatty acids, and nucleotides are the building blocks of life, linking in a chain with other molecules of their kind to make polymers. Amino acid molecules link to make proteins, monosaccharides produce carbohydrates (sugar), fatty acids together result in lipids (fats), and nucleotides combine to form nucleic acids in DNA and RNA. These chains of molecules then combine to form a living cell. These cells then result in life forms such as bacteria, fungi, plants, and animals. But life on Earth did not originate instantly. It took almost 700 million years for the constant bombardment of asteroids to stop on our planet so that life could have a chance to thrive.

 

 

 

Are we the only one?

Were the molecules of life made exclusively on Earth? While it is possible, an alternate scenario is that these molecules were formed in space and then delivered to our planet. This may sound like a script from a science fiction movie but in the past, meteorites have fallen on Earth and have shown the presence of biomolecules. In 1969, a meteorite fall was observed near Murchison village in Australia. The meteorite weighed over 220 lbs and was named Murchison. When the fragments of the meteorite were analyzed, they were found to contain amino acids, nucleotides, and sugars. Recent space missions have collected samples from asteroids in space. The samples are being analyzed and have been found to contain biomolecules essential to life.

A planet that is beyond our solar system is called an exoplanet. As of now, more than five thousand exoplanets have been confirmed by the National Aeronautics and Space Administration (NASA) and trillions are waiting to be discovered in the future. Why so much buzz about these celestial bodies? Because many of the exoplanets have conditions similar to Earth that can sustain life. Is it possible that the molecules of life can only be produced or delivered through a meteorite on our planet? Maybe not. If this is true then we may not be alone in the Universe.

If there are aliens in our Universe, will they be like us? or will our cosmic neighbors be more advanced, more intelligent, and more aware than us? If the latter is true then we may have to rethink awarding Miss and Mr. Universe on Earth. But the famous Nobel Prize-winning physicist, Enrico Fermi thought otherwise. In 1950 during a lunchtime conversation about extraterrestrial life, he simply asked "where is everybody?" By that he meant to emphasize that if there are intelligent and advanced civilizations outside Earth then they should have visited us by now. This is famously known as The Fermi Paradox.

Fermi had a strong argument to put doubt on the extraterrestrial search for life. But there can be counterarguments to revive the search. It is possible that advanced and intelligent alien life exists but is not interested in visiting us. It may be possible that there is life in other places but is not intelligent or advanced like us. Alien life may still be in the form of microorganisms or plants, or even animals not capable of making technological advancements.

 

Are there more Earths?

While the possibility of other habitable planets puts our authority over Earth at stake, it also gives us a list of new places to colonize. Are there other planets that can be our new home? At present, there are severe challenges with habitation outside the Earth. While it may not be possible in the near future but surely the idea of space colonization has fascinated a number of artists, scientists, musicians, and probably other animal species that have visited outer space.

 

Do we know enough?

The human pursuit of understanding the Universe pushes the boundaries of our knowledge. Even though we have made huge progress in understanding our Universe, we can only observe less than five percent of it. The rest of the Universe is made up of something we do not know about. With our cosmos being so vast and so little understood, many questions await us to be answered. The only thing we can do best as humans is to imagine and question. So, what are the most puzzling questions for you to answer?