There are many unknowns about the history of Earth, but then again there are many unknowns about pretty much everything. I feel the more I learn, the less I know. What a tricky dichotomy. Before delving into the beginnings of Earth I think it is important to give a hat tip to the most widely accepted scientific theory of what got us to the formation stage in the first place. The Big Bang Theory.
A scientific theory is much different than the typical theory one formulates in their head. Scientific theories are testable and incorporate hypothesis, facts and laws to formulate an explanation for an aspect of the world we live in. The Big Bang Theory, specifically the Lambda-Cold Dark Matter model or standard model, is the theory that explains the creation of the Universe. First developed in the early 1900’s it has been reworked and tested an infinite number of times into the model we know of today. In the simplest of terms, everything, and I mean absolutely everything, originated from one tiny point that expanded so violently and exponentially, matter, space and time began all at once. The expansion was so intense, the radiation can still be observed today. Now I want to clarify, I don’t necessarily believe this theory and it’s not because I don’t trust science. I just think there could be other explanations we have yet to discover. Also, if everything began from one single particle smaller than the nucleus of an atom, where did that particle come from? How did it get so hot that is exploded at such a magnitude it created the universe? We can’t explain how something started from nothing, it’s all a mystery. I love exploring theories and hypothesizing what all of this is, I am not married to any idea, just simply the messenger to the endless possibilities.
Imagine if every night we could look up and see the sky the way our ancestors did before the invention of electricity. Most of us live in areas where catching a glimpse of the Milky Way is impossible due to the amount of light being emitted into the atmosphere. But just because we can’t see something doesn’t mean it isn’t there. In the early 1900’s Edwin Hubble began looking at the brightest starts in the galaxy, examining the apparent luminosity of nebulae clusters and estimating the mean distance from Earth based on the speed of light. Basically, he quantified the luminosity and measured the change over time and used the speed of light as a constant to determine how far away these clusters were in relation to Earth. Ultimately concluding in 1929 the universe is expanding. This conclusion has been further supported with technological advancements and our ability to view greater distances into other galaxies. Since the universe is believed to be continuously expanding, this implies it was denser, hotter and smaller in the distant past. Further evidence to support this conclusion came about 36 years later with the discovery of cosmic microwave background (CMB) radiation. CMB is, in short, leftover radiation from the Big Bang.
Arno Penzias and Robert Wilson were building a large radio receiver at the Bell Telephone Laboratory in New Jersey when they discovered excess noise, ultimately realizing it was CMB that had been predicted to exist by Ralph Alpherin in 1948. CMB is invisible to the naked eye and although this was not always the case, it is very cold. Approximately 2.725 degrees above absolute zero and shines in microwaves along the electromagnetic spectrum. If we were able to see this wavelength, a bright glow across the entire sky would appear uniform in every direction. In hindsight this seems for the better, how distracting would that be. The uniformity of this radiation is one reason it is interpreted as remnant from the Big Bang. Alternative explanations have been explored for sources of this type of radiation, however none have been deemed a sounder theory.
In the very early stages, the universe was so hot free electrons and nuclei (neutrons and protons) were the only matter present. As things began to cool, the first element, hydrogen, was able to form. This transition from free electrons and nuclei to the formation of hydrogen can actually be observed through the behavior of CMB photons. Photons are weightless particles representing light. Imagine you are driving down a dark road with your high beams on and you hit a patch of dense fog. The brighter the light the less you are able to see. CMB photons scattered off these free electrons like light wandering through dense fog. This type of scattering produces what is called a “blackbody” spectrum of photons. In 1989 NASA launched the COBE satellite which carried a Far Infrared Absolute Spectrophotometer that measured and compared CMB with blackbody to a precision of 0.005%. 34 equally spaced points along the blackbody curve were measured and compared to the predicted energy spectrum, the result was a near perfect match.
Over the next several billion years slightly denser regions of the Universe became gravitationally attracted to one another forming gas clouds, galaxies, stars and other astronomical structures. Ultimately, forming the Milky Way galaxy and solar system in which we inhabit. It can be difficult to imagine this process took 13.8 billion years, but that should give you an idea of the vastness of the Universe. As technology has advanced our understanding of what is beyond our solar system has only grown. We now know every star has roughly a dozen planets. Although there is no confirmed evidence of extraterrestrial life, from my perspective if the number of plants is infinite it seems unrealistic to think we are alone.
Stay well all,