What is one of your favorite scientific discoveries and how has it impacted your life?
I love this question, though it's not an easy one!
Lots of answers come to my mind, most of them concerning black holes, exoplanets, time, and (of course) all colours and shades of neuroscience. But...
In 1953, two researchers working at the University of Chicago, Miller and Urey, put four very basic substances - water, methane, ammonia and hydrogen - in a closed circuit, heated the water so that it would evaporate and added a few electrodes among which sparks were fired. Such an environment was meant to simulate the Earth's atmosphere in the days of its forming. Miller and Urey didn't have to wait long for the results. After a week, atoms have formed many of the so-called "life particles": various amino-acids (both in their L and D forms), sugars and lipids. Later it was discovered that the same mixture can result in obtaining nucleotides, as in DNA. All it took was a chain of spontaneous chemical reactions, all "driven" by one principle: the less energy a molecule has, the more stable it is - and, obviously, it has a greater chance of lasting longer and forming strong bonds with other stable molecules.
I've heard about this experiment during my first year of studies and it blew my mind. Just think: it portrays life as something that was bound to happen, that was effective and filled an important gap in the system. Given the number of different molecules obtained (and - just a reminder - most creatures on Earth use only 21 different amino-acids), there are countless possibilities of forms in which life could develop. Take DNA: we know at least 4 ways in which it can twist, differing in angles, density and course of rotation. Even humans have some of these weird forms in their cells, apart from good old B-DNA. And we're talking only carbon-based lifeforms. I'm pretty sure we're not alone in this universe.
In such a view, life sciences are the exact opposite of physics. Physics is about expanding universes, accumulating energy and growth of entropy; life is all about narrowing this system to a stable, low-energetic, highly entalpic form. It's a hard work against the reality that freely and naturally shifts towards chaos, and yet it's been quite successful so far. It might be a very far-fetched hypothesis, but my guess is that lifeless worlds just can't exist.