Time, the Universe and the Whole Darn Thing!
Part One: The Future of the Earth
By Allan EastmanGo back to Page 3
Earth: The Cradle of Life?
The planet Earth coalesced about 4.5 Billion years ago from the solar system’s accretion disc and it only took something like 10-20 Million years for it to take up its basic form and constitution. So, Earth is about 1/3 the age of the Universe proper. Apparently, shortly after the hardening of its crust after 100 Million years, Earth was impacted by a smaller proto planet which knocked off a sizable chunk of crust and mantle from its surface. This chunk was retained by the Earth’s gravitational attraction and became the Moon. The Moon is a unique body in the solar system because it is very light in density in comparison to the iron cored other major moons in the system, which formed in a similar fashion to planets before coming under the influence of whatever planet they orbit.
The other effect of this collision was to knock the Earth off its axis, resulting in the 23.5 degree tilt it exhibits as it moves along in its solar orbit. This tilt to our planet results in there being seasons here – a delightful conclusion to a cataclysmic event.
You could say that the fundamentals of Life also arrived on Earth from Outer Space, perhaps even literally. During its earliest periods of development – the first few 100 Million years or so – the very hot planet was bombarded from the cluttered up Space beyond by asteroids, comets and smaller proto planets which delivered ice to the surface. This transformed into steam and water vapor which began to form the first atmosphere, shielding the sun’s radiations and cooling the surface. And more importantly, it began to rain! The Earth’s Oceans – still the dominant feature of our Blue Planet and the womb of Life here – began to fill the shallows and depressions of the primeval rocky landmasses.
The simplest forms of life appeared on Earth about 3.5 Billion years ago. One theory has single cell organisms using the energy of solar radiation or lightning to transform chemicals to replicate itself, eventually developing the chains of RNA and DNA which led to more complex plants and animals and ultimately resulted in – us.
Another interesting idea is that Life on Earth may have been directly seeded from Space via asteroid hits. Just as simple bacteria have been discovered living in the most extreme environments on Earth – encased in Antarctic ice, embedded in solid rock, by the super heated volcanic vents in the deepest trenches of the Pacific Ocean – there is evidence in ancient fossilized asteroid remains of complex amino acid chains that originated somewhere else out in the Cosmos. If they arrived here as viable life forms, our very existence may be derived from the detritus of a long dead planet far off in the solar system or beyond.
Anyhow, to cut to the chase, Life bloomed and flourished here on Earth. One important development - from our point of view - occurred about 500 Million years after the earliest life forms. Some simple organisms began to practice photosynthesis. They used sunlight to transform carbon dioxide and water to carbohydrate energy sources. As a side effect, they gave off waste – a delightful little gas called Oxygen.
And Oxygen took over the planet. UV radiation transformed some of it to Ozone which formed a kind of shield that protects us still from the more harmful effects of the Sun’s same UV radiation – an early kind of cosmic inoculation. More importantly, Oxygen became a significant part of the Earth’s atmosphere - currently about 21% of the total. Ironically, for something that is essential to human life, the rising levels of Oxygen in the early atmosphere were a toxic poison to most of the Life on Earth and killed off the vast majority of them about 2.5 Billion years ago.
OK. Life appeared, evolved, transformed, was largely wiped out a number of times and now we have iPhones and post modern skyscrapers and Pad Thai. So much for the past, it’s time to delve into our future and start to chart our star’s, our planet’s and our own destinies.
But one last little cool item to ponder - remember all those heavier elements that were cooked up in the cores of those earliest Super Massive stars? Spread through the Universe by their Super Nova explosions, these elements became the construction materials of our Solar system, our planet and ourselves. The sand on that beautiful tropical beach? Silicon from the center of a star. The red earth that turns the pasture grass pink in the high meadows of Georgia and South Africa? Iron content from a Super Nova. Your blood is red because of the self same iron. Your teeth and bones are largely composed of calcium, generated in the hellfire of the nuclear fusion of a long gone star. Ditto gold, lead, magnesium and all those other trace elements found in our bodies and in the world around us.
So when some romantic poet or pale face folk singer goes on about “We are star dust,” you can say, “Yeah, that’s true!”