The periodic table was discovered mainly by chemists and was based on the electronic structure of the elements explained by physical chemistry. Nowadays, new elements are discovered in high energy colliders (physics) and the most recent element discovered in 1996, is called Ununbium atomic number 112 and its most stable isotope is 285.
Guess what? It has a lifetime of 280 microseconds 0.00280 seconds. So it doesn’t stay for long. Why? It has so many protons and neutrons that nuclear forces cannot hold them together.
As the atomic number increases, elements generally become less stable. Neutrons and a lot of quantum mechanics are used to understand stability, but eventually the forces of nature fail and large or radioactive elements decay into something else. Radioactivity is a hallmark of unstable elements.
However, these high atomic number elements are usually detected in high energy reactors. If that Ununbium element only lives for 280 ms, that means in our frame of reference we’re stationary in. In fact, in accelerators, Einstein’s relativity tells us that as particles move faster relative to us, they seem to live longer. So from our framework, looking at them move so fast, so they stay longer.
All these new elements are unstable and radioactive. They can play no role in life as we know it. In fact, we know all the stable elements. The Periodic Table puzzle started by Dmitri Mendeleev in 1869 has been completed and we have all the pieces for the stable elements, and much more. There are no other elements except these short-lived ones with high atomic number.
The interest today is not in finding new elements, but in understanding the smallest elementary particles that form when atoms collide. The Large Hadron Collider in Europe is doing just that. One particle they are looking for is the Higgs boson.
Conditions for Life
Also, if you look in the telescopes and do spectroscopy of different stars, guess what, we see the same elements as on Earth. So we can assume that the structure of matter is the same throughout our Universe and our periodic table is the same on distant planets. They have the same chemistry. If life exists, it is most likely carbon-based, like on Earth, and similar to what we know.
You are assuming that we should look for life in the center of our Universe because it has the longest time to evolve. Therefore, if time were the only factor, you argue, there would be more life there. However, the Universe is very old: about more than 13 billion Earth years. That’s more than enough time for evolution anywhere in the Universe, provided conditions are right.
Liquid water and a stable planet are needed for intelligent life to evolve. The best estimate for the evolution of humans is about 100 million years, but the life of a small cell evolves rapidly. The reason humans took longer is because we’re complicated, and throughout our Earth’s history there have been mass extinctions on the way (we know of 6 such events, but there could be more).
There are many other things we need for life to develop as well: a large moon to stabilize the Earth’s axis, plate tectonics (a long story), and many other conditions. For example, mass extinctions are caused by collisions with meteorites or other objects. A meteor 1,000 meters in diameter (that is, with a diameter 1/8,000 times smaller than Earth’s) would kill everything and boil the oceans, thus sterilizing Earth. At 100m a meteor would kill about 60% of life. Now we are lucky again. It’s been 4 billion years since a 1000m diameter meteorite struck us. There are two reasons for this: there are fewer such objects around (they’ve had 13 billion years to collide, so many have been removed). The other point is that Saturn and Jupiter are much larger than Earth and further from the sun. Their stronger gravitational pull pulls in many large meteorites, so they hit them before we do. Saturn and Jupiter protect us!! All these factors and many more have given us the conditions for life to evolve on a stable Earth.
We’re alone?
In general, people believe that life is ubiquitous, but intelligent life might not be. So astronomers look for planets like ours. In the past, we listened to the skies for stray radio signals, to no avail. At one point, astronomers zeroed in on a dense collection of stars, but it was concluded that the radiation was too intense for life to form. The Kepler Telescope was recently launched in 2009 and is searching for Earth-like planets. To date, more than a thousand candidates have been located.
Of course, these planets are usually hundreds, if not more, of light-years away. We can send radio signals to the planets, but it will be a long time before we get answers.
There are a lot of stars and probably a lot more planets and a lot of life out there. On the other hand, some people believe that intelligent life is very rare because optimal conditions for intelligent life are so unlikely. In other words, we are very lucky and we have to make sure that our Earth stays healthy for us.
