Science understands the universe via observations, which are organized into models through which the information is presented. Initially, these models are purely empirical, but deeper understanding and the ability to make predictions only comes when they are formulated with mathematics. As observations become more precise the mathematical models evolve and improve.
For examples,
(1) The experimental observations of
Galileo Galilei(1609) were formulated by
Isaac Newton(1687) into
Classical Mechanics and were refined by
Albert Einstein(1917) with the
General Theory of Relativity (GR). GR resolved a few discrepant
observations like the precession of the
perihelion of Mercury and predicted a few others like
Gravitational Lensing that has been observed(1979). His famous equation
E=mc2
showing the equivalence of Matter and Energy was demonstrated by the
Atomic Bomb(1945).
(2) The known chemical elements were arranged by
Dmitri Mendeleev(1871) to an
empirical
Periodic Table, which even
predicted the existence of a few
elements which were discovered only later. The table was only
understood with the discovery of the particles that constitutes the
atoms. Incorporating
quantum electrodynamics 3 of the 4
fundamental forces of interaction were unified subsequently as the
Standard Model of Particle Physics.
It incorporates
Special Relativity, but excludes Gravitation of GR.
There have been
many attempts since the 1980s, with various formulations of
String Theory to merge the Standard Model with General Relativity,
but none have been fully successful to do so.
(3) Charles Darwin's(1859) Theory of Natural Selection and evolution was comprehended only with the understanding of the encoding and replication of the DNA double Helix(1953) in all life forms and now leading Botany and Zoology which are mostly empirical to have a more logical structure, although not yet fully mathematical.
Each of these models looks at the Universe in a different way. Like a fishnet thrown to catch Fish from the sea. By measuring the size of the fish you catch, you may infer that all the fish in the sea are larger than 2 inches. However, when you see a few smaller fish you realize this inference is wrong and just reflects that most of the smaller fish would have escaped from the net, which has 2-inch holes. If you use a finer net you are able to catch smaller fish, but a solid net will catch no fish. Science may get close to reality, but the model will never be reality.
Photons of light looks like discrete particles as well as a wave. It depends on with which model you look at it. Consider a cylinder. In 2-dimensions, if you look at it from the top it looks like a Circle and from the side a Rectangle, when it, in reality, it is a cylinder in 3-Dimensions. Photon is neither a particle nor a wave it is an entity in a higher dimension which science can only describe with the mathematics of the Standard Model.
Einstein in GR merged Space and Time into a Space-Time continuum which makes our universe without boundaries but finite in volume. Consider a circle. It is a 1-dimensional line in 2-dimensions with a finite length and no boundaries. Next, consider a sphere. It is a 2-dimensional surface in 3-dimensions with a finite area and no boundaries. Next, step-up another dimension that is difficult for us to visualize without mathematics. Space-Time is a 3-dimensional entity in 4-dimensions with a finite volume and no boundaries. Science observe that the volume occupied by the universe is expanding, but still remains finite.
The next issue that needs to consider is the 19 fundamental constants used in our models of the Universe. Science can now measure them precisely, but can't be derived them from the models. Maybe a few of them will be constrained by Grand Unification, but not all. The Fine Structure Constant = 1/137.036 is a dimensionless quantity that measures the strength of the electromagnetic force. It can be shown that even a 4% variation of it will lead to far less Carbon and Oxygen in the Universe and life as science knows it. This has led to questions as to how the Universe is fine-tuned for life.
At this point, science has to go outside the regime of observation. We have either to assume that our universe is a simulation like in the movie Matrix or postulate that our universe is one of a large number in a multiverse. Then each would have one possible combination of fundamental constants. Science then use the anthropic principle to say that as life exists in our universe, it has to be one that has fundamental Constants conducive to for chemical evolution of life. The multiverse will be a higher dimensional space in which many independent universes will exist without any interaction.
Science has now determined the age of the universe is 13.8 billion Years old and that the Sun and Earth formed about 4.6 billion Years ago. The Earth took about 0.5 billion years to cool to allow liquid water. Science has found single cellular life that was on Earth at 3.8 billion years ago. So life originated on Earth in about 200 million years or about one orbit of the Solar System around the Galaxy.
Science has no good Chaos Theory to estimate of the probabilities for chemical evolution of life. Although we now know most stars have planets and many have habitable planets around them, Science has still not detected any signs of life. This is not surprising as the first exoplanet was confirmed only in 1995.
As life exist on Earth, it is one place chemical evolution happened, and has a common origin. If 200 million years is far too short to expect it, then we can invoke the anthropic principle again and use all habitable planets in the Galaxy or Universe to get as large a multiplicative factor as needed.
PanSpermia asserts life originated in Space and was deposited on Earth via comets does not give a large factor. The age of the universe is only about 50 times 250 million years. The cross-sectional volume of the galaxy intersected by even the Oort cloud which extends to 1 light years in one 250 Million year orbit is about 10 millionth of the Galactic disk. So life would need to very densly populate the Galaxy. All life on Earth Based on DNA deoxyribonucleic acid (DNA) is encoded with four bases: adenine (A), thymine (T). cytosine (C), guanine (G) The two strands are held together by hydrogen bonds between pairs of bases: adenine pairs with thymine, and cytosine pairs with guanine. Virus have ribonucleic acid (RNA) that has Five with addition uracil (U) and sometimes, aminoadenine (Z) instead of adenine.
There are many such possible nucleobases and if life evolved independetly then it is unlikely it would use the same Nucleabases as life on Earth. If we find life in some other place in our solar system and it has the same Nuclearbases then it is mostly contamination from Earth. If we find same in some other solar system of our Galaxy, then Panspermia has more credibility. If we find different in our Solar System or some other solar system in our Galaxy, then we would need to reconsider the probabilities of chemical eveolution of life.
Astronomical distances can be measured by the time it takes to travel that distance at the speed of light=299,792,458 meters per second. In light-seconds the diameter of Earth is 0.04, the distance from Earth to the Moon is 1.3 and the Sun 500. Our Solar system is 5.5 light-hours in radius and the nearest star is 4.3 light-years away, a factor of 7000 more distant. The Sun is 25,000 light years from center of our MilkeyWay galaxy which is 100,000 light-years across. As space is expanding, the Cosmic Microwave Background (CMB) radiation reaching us from 13.4 billion years ago is estimated to be now over 45 billion light-years away.
If we take 13.8 billion years as one cosmic-year then in the year which has 31.5 million seconds, each cosmic-second is 437 years. So Human history is just 15 cosmic-seconds and the HomoSapiens were there just 10 cosmic-minutes. Dinosaurs went extinct just 42 cosmic-hours ago (66 million Earth years).
So in both Space and Time, Human life on Earth is just a tiny flash.
If our universe was just a matrix-like simulation, then "God" could have programmed anything even irrational like Astrology into the simulation. However why would any "God", intelligent design such a large Space-Time continuum for just this tiny flash, in which all human created myths and religions exist?
There are observations such as Dark Matter and Dark Energy that are not fully understood with our current scientific models. One must remember that most of our current understanding of the universe is less than 150 years old. So unless humans destroy progress of Science, the greatest discoveries are yet to come.
This article assumes reader has a bit of Scientific knowledge.
I think I could have handled it with O'level Science Knowledge.
Not sure if the current O'level is sufficient or if it is the current
A'level, or Undergraduate.
I am trying to give in this synopsis of about 1250 words, the global
science perspective rather than the details which can be read in the
extensive underlined 49 links to Wikipedia, and three Videos.
I thank Dr Nalin Samarasinghe for his corrections, most of which were incorporated.
Please send comments to improve the wording and clarify what is not
clear
Thanks, Stay Safe, Dr Kavan
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