Sunday is my day for spiritualism and philosophy. So today I inquire into why we are here. There is, of course, the biblical version, where God created everything. But you can refer to the Bible or Quran or other historical source to find this answer.
This not a particularly religious blog site, so I will instead today look into how Homo sapiens came to be and maybe not quite answer the question of why we are here.
- The Big Bang, followed by the subsequent formation of stars and galaxies, is the leading theory of our beginning, from which came our solar system with Planet Earth, then evolution to us. You've seen these forms of graphic before:
- Clearly, there are galaxies, and our Milky Way is but one.
- When you look up into the night sky, almost all what you see are stars from our own galaxy. If you searched and searched with your naked eye, you would be able to see only three galaxies. The others are too far away.
- However, the James Webb Space Telescope took the photo to the right, and what looks like stars are almost all galaxies.
- One recent source says that there are 20 trillion galaxies in the observable universe.
- We live in an average galaxy, which is huge, for this graphic shows that it would take an object, moving at the speed of light, 100,000 years just to move from one end to the other. Where were we humans 100,000 years ago? Living in caves. Agriculture was only developed 10,000 years ago. Latest studies now, actually, show that our galaxy is twice the diameter of what we thought, and that drawing to the right should now indicate 200,000 years.
- There are between 200 billion and 400 billion stars just in our Milky Way, and the larger galaxies have more than 100 trillion stars. The Andromeda Galaxy, which is our closest neighbor, around 2.5 million light years away, has over a trillion stars.
- No one is sure how the Big Bang happened, and there are only speculations on how life formed on Earth.
- The process where non-living matter formed self-replicating, complex molecules, then into cells, is called abiogenesis.
- For our planet, this probably occurred in hydrothermal vents or shallow ponds over many millions of years. But then, maybe asteroid impacts played a role.
- Key ingredients include organic compounds with elements that include carbon, hydrogen, oxygen, nitrogen and phosphorous, plus a source of energy.
- What we do know was first suggested by the Miller-Urey Experiment carried out in 1952 at the University of Chicago.
- This was a chemical synthesis experiment (from inorganic constituents to organic compounds) simulating the conditions thought to be present in the early, prebiotic Earth, maybe 3.7 billion years ago.
- Used methane, ammonia, hydrogen and water, sparked by an electric arc.
- Produced were amino acids.
- Interestingly enough, more than half a century later, a re-analysis was made examining sealed vials, showing a lot more amino acids than originally measured.
- Amino acids lead to self-replication and proteins, but no one has been able to produce actual life in a lab.
- Somehow, RNA formed, a very big somehow, leading to cells and early life forms, around 4.1 billion years ago. Keep in mind that Earth only formed 4.54 billion years ago.
- Bacteria came first, followed by Archaea and Eukarya. These are the three domains of life.
- Around 2 billion years ago, a larger prokaryotic cell engulfed an aerobic bacterium.
- Then came complex cells.
- You might not know this, but we humans are all eukaryotes.
- Then, how did intelligent life develop leading to us, Homo sapiens?
- Evolution? You can read the details.
- Panspermia?
- This theory argues that life did not originate on Earth, but instead evolved somewhere else and was seeded by extraterrestrial aliens.
- In 1903, Svante Arrhenius (the guy who early studied the Greenhouse Effect, where he predicted of the now global warming--won a Nobel Prize, and went on to become director of the Nobel Institute), hypothesized that early microscopic life came from space.
- Ron Bracewell of Stanford.
- I might add that my summer at the NASA Ames Research Center in 1974 resulted in a concept to better detect extrasolar planets. You can read about this concept here.
- Garry Noland, also from Stanford, says that DNA is 9.5 billion years old.
- But back to natural evolution, this article reports on the 1983 insight of Brandon Carter from France.
- There are 300 million potential biological experiments just in our galaxy. The odds of success are low, but if life happened here, chances are that this could happen elsewhere too. The Darwin evolution concept should prevail, but what might become life, will almost surely not resemble us at all.
- Some solvent must be present, but it would not necessarily be water.
- Alien life might not be based on carbon.
- I've long believed that we are but a step towards an ultimate evolution that will lead to a form of Artificial Intelligence that in time to dominate the universe.
- Why haven't we detected extraterrestrial life?
- Our universe is 13.8 billion years old, and logic would argue that there should be some sign, beyond those flying saucers that have entertainment value?
- Maybe space is too vast, and no entity will ever get too far from home.
- Yes, but there are ways to signal, rather than travel.
- Perhaps it's a matter of timing, for our technological society is less than a century old.
- In time, something non-biological, in some form of AI, should be able to spread into space.
- Who knows the ultimate fate of the universe, but one theory has it expanding forever as the Big Chill perhaps lasting a 100 trillion years from now, so there is time.
- Thus, why are we here? I don't know.
- Then again, maybe the answer is what I said above: we are but a phase of evolution.
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