Within the heart of man is a void that can only be filled with answers, answers to the most haunting questions of life. Who am I? Why am I here? How did all of this… come to be? Those questions are fundamental to our being, they make us human. They are the questions that all people should ask themselves and do ask themselves at some point in their life. To answer these questions we must ascertain the truth from wherever the truth may reside, whether in scripture, philosophy, history, logic, science, mathematics, or from our own experience.
The Eternal Universe
In order to begin our search for the truth, we must first examine the very origins of our universe. Because, whatever truth lies in that distant past, it will help us begin to answer those fundamental questions. The first set of questions that we need to address are whether the universe even had a beginning? Is it eternal? Or did it have a distinct time in which it began its existence? Is it temporal? Because, whether or not the universe, even had a beginning influences the facts that we can observe. The beginning or lack of one is a foundation that we will build upon in our examination of Apologetics.
The point of view that dominated the early part of the twentieth century was that the universe was eternal. That it had no beginning and no end. The eternal universe theory was not a new idea. The idea traces its origin back to the ancient Greek philosophers, notably Heraclitus of Ephesus (535 BC to 475 BC) and maintained its persistence throughout history.
Apologetic Implications
The eternal universe theory is noteworthy in the fact that if the universe had no beginning, then the explanation of its creation can be overlooked. That is, if the universe is everything that we know to exist; space, time, matter, and energy. That “everything” has always existed; therefore, it had no point in time where it could have been created.
Philosophical Issues With the Eternal Universe Theory
There are problems with the eternal universe theory. One is with the use of an infinite length of time. The issue can be explained this way; if there has been an infinite amount of time before your birth, then your birth would not have taken place. This is because you would have to pass through an infinite amount of time in order to reach your birth. Thus, you would only arrive at the time of your birth by passing through a finite amount of time.
General Relativity Issues With the Eternal Universe Theory
Another problem with the eternal universe relates to what is known in physics as Einstein’s blunder. Albert Einstein developed his set of field equations for the theory of General Relativity in 1915. The equations relate the curvature or warping of space to the amount of matter and energy occupying that space. This curvature of space and time around matter is one of the theories to explain the gravitational forces between objects.
At that time, the universe was observed to be constant size and static due mainly to the precision of scientific instruments. The instruments lacked the precision to measure properties of the universe to show that it was indeed expanding. Thus, giving credence to the eternal universe theory. However, in order to make the set of field equations work for a static universe model, Einstein had to add what is known as the cosmological constant. The constant is represented as the Greek letter lambda Λ as seen in the equation above. This placement of lambda in the equations allowed for a correction that kept the universe at a constant size and static. Without the cosmological constant the equations described a universe that could be either contracting or expanding. This solution worked for a time until Edwin Hubble’s observations lead to the evidence that the universe was indeed expanding and there was no need for the cosmological constant in order to keep the universe static.
Einstein was known to have regretted this seemingly arbitrary addition of the constant to his equations. However, his equations in their original form without the cosmological constant accurately predicted an expanding universe. Later in a twist of fate, the cosmological constant was added back to the equations when in 1998 the universe was observed to be expanding at an ever-increasing rate.
Expanding Universes are Temporal
If the universe is shown to be expanding or undergoing what is called in physics “inflation” it has been proven that it cannot be eternal going backwards into the past. In their research paper entitled “Inflationary Space-times are Incomplete in Past Directions” Arvind Borde, Alan Guth and Alexander Vilenkin describe in the discussion section:
“Our argument shows that null and timelike geodesics are, in general, past-incomplete in inflationary models, whether or not energy conditions hold, provided only that the averaged expansion condition Hₐᵥ > 0 holds along these past-directed geodesics.”
Meaning, that in an inflationary universe that is undergoing an average positive expansion rate (Hₐᵥ) the universe can expand into eternity. However, the inflationary universe has to have a finite past in which a singularity exists. It cannot be eternal in the past. This is known as the Borde-Guth-Vilenkin Theorem (BGV Theorem) and is helpful to link together the expanding universe to a space-time beginning represented by a singularity. The BGV Theorem’s validity relies on simple kinematics and is not reliant on general relativity; thus, if the theory of gravity was to be changed or modified it would not change the outcome of the BGV Theorem.
Thermodynamic Issues with the Eternal Universe Theory
The eternal universe also runs contrary to known physical laws, notably the second law of thermodynamics. The law states:
“The entropy of any isolated system never decreases. In a natural thermodynamic process, the sum of the entropies of the interacting thermodynamic systems increases.”
This states that the energy in the universe is constantly becoming more disorganized and more uniformly spread out as time progresses. The unit of measure of this disorganization is called entropy in thermodynamics. The universe is the ultimate isolated system as it contains all energy and matter that we know of and there are no external energy sources to reverse entropy. Thus, the universe will ultimately arrive at a point in time where it reaches what is called “heat death” or maximum entropy. This is when all energy is completely homogenized throughout the universe and no thermodynamic processes can function anymore. This is because all processes need a gradient of energy or the movement of energy from high levels of energy to lower levels to be able to work. This movement of energy drives the process, whether the growth of a plant or the engine in your car. However, any process that takes place always comes at the expense of its surroundings; thus, entropy always increases in the isolated system.
Since the universe has increasing entropy and is destined for an eventual heat death, the universe would have died an infinity ago. This is because an infinite timeline any point is preceded by an infinite amount of years and followed by the same infinite amount. This problem is very similar to the logical problem previously discussed.
We can determine, by using the facts that have been discussed, that the eternal universe theory is highly improbable and doesn’t fit the evidence we observe. Although, at times throughout history the eternal universe theory has become favorable; it has numerous flaws that are both scientific, philosophical, and logical in nature. The eternal universe theory should most likely be discarded as a possibility in favor of a universe that is temporal.