I have read many books on astronomy and physics. Here are a few of the important ideas that stuck with me:
- We have deduced mathematical laws of physics that accurately describe and predict the universe’s behavior.
- Some of the laws of physics, such as quantum mechanics, are very strange but they work remarkably well.
- The universe began about 13.8 billion years ago as a big bang of extremely dense energy.
- A few constants define how the universe evolved after the big bang. It seems these constants could have been different resulting in a completely different universe. We do not know why they are the way they are.
- We do not and probably never will know what existed before the big bang, nor whether our universe is unique or one of many, nor whether our universe is infinite or finite.
- As the big bang expanded and cooled some of the energy converted into light gases.
- These gases formed clouds which collapsed under gravity to form stars.
- As these stars aged some exploded and created heavier elements like carbon and other materials necessary for life.
- Some of these heavier elements collapsed into new stars and planets including our sun and earth about 4.5 billion years ago. All life is thus amazingly composed of exploded star-dust.
- There are a mind-boggling 300 sextillion (3×1023) stars in the universe and probably more planets.
- Shortly after our earth formed it was randomly struck by a mars sized body which created our moon.
- The moon helped to create an environment hospitable for life by stabilizing earth’s rotation and creating tides.
- Our sun will use up its fuel and consume the earth in about 6 billion years.
- The universe’s expansion is accelerating and we do not know what the “dark energy” is that is causing this.
- We calculate more gravity than should exist for the mass we observe and we do not know what this “dark matter” is.
- 95% of the universe is dark energy and dark matter (the stuff we do not yet understand).
- The universe began as high quality dense energy and most scientists think it will end in about 100 trillion years as low quality diffuse energy – cold, black, and without life.
The amount we understand about the universe is quite remarkable and is something to be genuinely proud of as a member of the human species.
We have found no need for a god to explain anything in the universe, unless we want to assign a reason for the laws of physics being the way they are, in which case such a god would have no resemblance to any of the gods worshiped by our many religions.
I find it enlightening to contemplate the purpose or objective of the universe.
Since the universe started as high quality dense energy and its destination is low quality diffuse energy it is reasonable to state that the objective of the universe is to degrade energy.
Structures and mechanisms which degrade energy can and will form provided they are consistent with the laws of physics. Those structures and mechanisms which degrade energy the most effectively are the most likely to exist.
Another way to think about this is that wherever an energy gradient exists, things (work) can happen, and given enough time they will happen, provided the laws of physics permit it.
Humans are the Earth’s most effective species at degrading energy. We dominate the planet because of this talent, and although in the process we are causing the extinction of many other species and probably causing our own collapse, it is interesting to observe that humans are doing what the universe wants. That is, burning all of the fossil energy as quickly as possible to convert it into low quality waste heat thus helping the universe to arrive at its destination as quickly as possible.
If humans had not learned to exploit fossil energy then some other species would probably have evolved to exploit this energy gradient.
It is probable that intelligent life has evolved many (but not too many) times in the universe but always collapses shortly after it learns how to exploit fossil energy. This may explain why we have not heard from any other intelligent life despite years of listening.
This interactive tool titled The Scale of the Universe 2 by Cary Huang is excellent for helping to visualize our place in the universe:
Or if you prefer to watch it as a video: