Did the Universe Have a Beginning?
- Jason Pluebell
- Aug 31
- 33 min read
For many centuries, scientists and philosophers have pondered the possibility of a temporal universe. At first, they tried to answer the questions from logical and theological principles. People like Aristotle (4th century BC) saw time as a sequence of connected events, and that if the universe began, it would have started by the end of a prior event. He thought that to postulate time as having a beginning was absurd. During the Middle Ages, many Jewish and Christian philosophers affirmed the idea of creation ex nihilo, or from nothing. People like Augustine, Aquinas, Maimonides, Bonaventure, and many others affirmed this view (Stephen Meyer, Return of the God Hypothesis, Pgs 69-70). Many theologians from this period argued from the Kalam Cosmological Argument by showing the absurdity of actual infinities existing in the physical world (See What is The Kalam Cosmological Argument?). If a man tried climbing from an infinitely deep pit, he would never be able to escape because he would have an infinite distance left.
Then scientists began wondering if the universe contained an actually infinite amount of matter and space. Some held to a finite universe, but with infinite space, such as Issacc Newton. But some recognized that an infinitely large universe would exhibit a uniform distribution of stars that would light the entire sky, concluding that if space extended infinitely, every line of sight would terminate with a light source. This paradox was named the "Olbers' Paradox," named after Heinrich Wilhelm Olbers. Some folks offered explanations, such as the starlight exhausting before it reached Earth due to a substance called "Ether" that was absorbing all the light. Nonetheless, it wasn't until Man began looking at the heavens with even greater instruments than before that he discovered the answer to this age-old question.
In this article in the Origins of the Universe series, we will look at the scientific discoveries that led to the ultimate discovery that the universe had a beginning at some point in the past.
Distant Starlight Red-shift
Nebulae: Gaseous regions of space visible to the naked eye or a telescope that consist of stars that light up the gases.
Entering the 20th century, many affirmed an infinite age to the universe for various reasons, including Newton's framework of infinite space, which some implied as infinite time aswell, and Uniformitarian dates for the age of the Earth being extrapolated to the universe, and other deep time theories. This position was simple and had few issues because there was no need to posit an origin if there was none. But it wasn't long before an astronomer at Harvard College Observatory claimed the entire universe contained our Milky Way. He measured the size of the Milky Way to be about 300,000 light-years across, but many scientists began leaving this model because of observations of objects called Spiral Nebulae. In 1715, British astronomer Edmond Halley described six individual nebulae, but later telescopes and better photos offered evidence that these clouds contained many different clusters of stars.
This eventually gave birth to a debate between Harlow Shapley and the astronomer Heber Curtis. The debate took place at the Smithsonian Institute in 1920, where they discussed whether these nebulae were either inside or outside the Milky Way. As expected, Shapley argued that these clouds existed inside the Milky Way. It wasn't until several years later that Edwin Hubble settled the debate, but his work relied on the prior work of another astronomer.
Illuminating The Calculations
Harvard College Observatory would hire women to scan photographic plates to make records of stars and observations. This is where Henrietta Leavitt (1869-1921) began working, examining plates. Photographic plates were used because they could be exposed to the sky for extended periods, catching objects the human eye could not normally see. These plates enabled astronomers to make even more accurate observations of the night sky. Leavitt was deaf, but had a knack for analyzing the smudges left on the plates to find and catalogue stars. During her work analyzing plates, she made a discovery. Leavitt discovered a specific star called a Cepheid Variable Star, a type of pulsating star. She found that the brightness of these cepheids in a nebula called the Small Magellanic Cloud oscillates with a period that correlates with the magnitude of their brightness. In other words, the brighter the star, the longer the pulsation period; and the longer the pulsation, the greater the apparent brightness.
Apparent brightness is measured by using a photometer, which measures the amount of photons that arrive in an observed area per second. Absolute Brightness is measured using standard distance measurements. The absolute brightness only varies with pulsation, whereas the apparent brightness varies with pulsation and distance. Stephen Meyer offers an analogy to aid us in understanding why this matters to an astronomer:
“…imagine looking at a light coming from a lamppost through the fog while walking through a park at night. If you see a light in the park that looks extremely bright to you, you might attribute that apparent brightness to the light being extremely close at hand. Or you might attribute the brightness of the light to an extremely high-output lightbulb located on the other side of the park. (Meyer, Return of the God Hypothesis, Pgs 76-77)". Unless you know the distance to the light source, you have no way to calculate the actual brightness at the source from what you're seeing from a distance.
Astronomers faced a similar issue using apparent brightness to calculate the absolute brightness and distance of a star. They can measure the apparent brightness of a cepheid variable star, and they also know that light intensity dissipates with the distance travelled, specifically by the inverse of the square of the distance, or 1/d2. But they can only calculate absolute brightness if they know the distance to the star they see, and the distance ot the Magallanic Cloud was not known, so Laevitt was not able to calculate their absolute brightnesses from their apparent brightnesses. She could, however, plot the relationship of how both apparent and absolute brightnesses varied with the period of pulsation of the cepheids. Thus, to calculate the distance of the cloud, there must be a cepheid somewhere that has a distance we can calculate.
In 1913, Danish astronomer Ejnar Hertzsprung used a method called statistical parallax to determine the distance to 13 individual cepheids that were relatively close. Normal Stellar Parallax measures the position of a star in the sky at six-month periods, when the Earth is on one of two sides of the Sun. The method uses trigonometric formulas to determine the distance via the differences in angular displacements at the two six-month periods. But Statistical Parallax, "assumes that stars move in random directions, so the distribution of radial velocities, Vr, (velocity moving directly toward or away from earth) and the distribution of tangential velocities, Vt, (velocity perpendicular to the radial velocity) are roughly the same. The radial velocities can be calculated using the Doppler shifts in the stars’ emitted light. The tangential velocities cannot be measured, but the angle, θ, that a star moves across the night sky over some time interval, t, can be. (Return of the God Hypothesis Extended Research Notes, Note 4d. A.Final Extended Research Notes)."
Hertzsprung first found a cepheid in the Magallanic Cloud with the same period of pulsation as the ones he found near the sun. Since all cepheids with the same pulsation have the same absolute brightness, he was able to find the absolute brightness of whatever cepheid he was observing. He calculated the distance to be about 30,000 light-years away, but since nobody knew the extent of the Milky Way yet, there was no way of knowing if it was part of our galaxy or not, or if the universe only contained ours (Meyer, Return of the God Hypothesis, Chp 4 Note 35).
Another Galaxy...
Now we return to Edwin Hubble, who began working at the Hooker Telescope in California in the 1920s. He specifically observed a 40-minute exposure of M31, the Andromeda Nebula. Hubble saw some Novae, which turned out to be two novae and a cepheid star (Novae are stars that increase in brightness, then decrease gradually over a long period of time).
Then, using Leavitt and Hertzsprung's methods, he recorded that the Cepheid in Andromeda brightened and dimmed over a period of 31.415 days and calculated its absolute and apparent brightnesses, which enabled him to determine its distance. He concluded that the Adromeda Nebula was 900,000 light-years from Earth, though modern measurements establish it at 2,500,00 light-years away. Hubble claimed that Andromeda was not a nebula, but actually another galaxy, and that the universe was much bigger than what Shapley had proposed in 1920.
Starlight Red-Shift
In 1912, an astronomer named Vesto Slipher utilized a 24-inch telescope and the spectroscopic method to study light from astronomical bodies. When an atom absorbs energy, the electrons become excited and jump to higher energy levels. They then decay back to more stable energies, emitting a photon in the process that releases the energy they have gained. The energy of the photon is proportional to the frequency and inversely proportional to its wavelength. The equation for finding the energy of a photon is E = hf, where f represents the frequency of the light and h represents Planck's constant, a fundamental physical constant used to calculate the energy level from the frequency. The study of the light emitted and absorbed by chemical elements, their wavelengths, frequencies, and colors is called Spectroscopy. When a certain element absorbs energy, it releases photons with specific frequencies and wavelengths due to each element's unique energy level.
When light is pointed at a prism, its wavelengths are all divided, creating what we see as a rainbow, which represents only a small portion of the electromagnetic spectrum, or the full range of the wavelengths of light. What we see in the rainbow is the portion called the visible light spectrum. The full spectrum includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays (listed from longest to shortest wavelength). This can either be a spectroscopic emission or absorption of light by a chemical element. In a spectrometer, the patterns of the emitted wavelengths are called spectral lines. Astronomers use this to determine the chemical composition of stars and galaxies via the light they emit. Which leads me to a kind of off-topic tip. When astronomers discover an exoplanet that they claim has possible life, they are not actually looking into a telescope and seeing a blown-up image of the planet.
When an exoplanet (a planet that orbits a star outside our solar system) is detected, it is detected by means of observing a star's behaviour and brightness changes to infer that a planet is there. It is then that they use spectrograph readings to determine the atmospheric makeup of the planet. Nowhere does anybody actually have a view of a planet, and the pictures seen in YouTube videos and news articles are just an artist's imagination, not what is actually there. It's more analogous to seeing the lampost in the fog flicker, then inferring that a moth may be smacking into the bulb.
Anyhow, Slipher used this method to study the spectra of astronomical bodies. In 1912. He began measuring the light from several spiral nebulae and found specific element patterns for each one. But he noticed something strange about the patterns; the lines of the nebula were all shifted towards the red end of the spectrum. In simpler terms, the patterns he observed were at a redder placement than what would be observed from elements on Earth: the light had longer wavelengths. This is known as the Doppler Effect, where wavelengths are shortened if they originate from a source moving towards an observer and stretched if they come from one moving away. Thus, if we observe a galaxy with red-shifted light, we conclude it is moving away from us. Slipher saw that stars that we know are in the Milky Way may have a blue or red shift, but that "more indistinct" nebulae exhibited a greater red shift, implying they were moving away from us. By 1914, Doppler shifts had been recorded for 13 of the brightest galaxies, but the record was dominated by red-shifted galaxies as opposed to the expected equal mix of red and blue.
Hubble's Constant
As Edwin Hubble examined Slipher's red shift records and other work from Milton Humason, he found that more distant galaxies had greater red shift. Around 1920, he began further Doppler shift observations at the 2.5-m reflector at Mt. Wilson, and by 1925, he recorded 45 Doppler-shifted galaxies. In 1936, he noted that red shifts completely dominated the catalogue:
"The numerical values of the new velocities were found to be surprisingly large and of an entirely different order from those of any other known type of astronomical body. (William K. Hartmann, Astronomy: The Cosmic Journey, Fourth Edition, Pg 554)"
There were red shifts with recession speeds as high as 1800 km/s on this list. In 1928, an American physicist named H. P. Robertson noticed that the more distant a galaxy, the greater the red shift, with the red shift directly proportional to distance.
This suggested that the further away a galaxy was, the faster they were receding from us. His discovery of the relationship between recessional velocity and galactic distance has been named "Hubble's Constant". This discovery further implied that the universe was experiencing some sort of outward expansion. If a galaxy were five times as far as another, it would be receding five times faster. Hubble found that the rate of recession of a galaxy was directly correlated to the distance it is from us. Taking this into consideration, at any time in the past, galaxies would have been closer together. As you go further back, all the matter in the universe would have to necessarily converge at a single point where the universe began. Hubble's Constant (H) lies somewhere between 77 ± 14 Km/s per megaparsec. One megaparsec is about 1.92 x 1019 miles (or 1,920,000,000,000,000,000,000 miles). This means that a galaxy 1 Mpc away will recede on average about 77 km/s. One that is twice as far will move 154 Km/s, and one 10 Mpc away will recede at 770 Km/s.
A Banging Beginning: The Big Bang Model
During this period, and some time after it, there were not just advancements made in observational data that led to the conclusion of an expanding, finite universe. There was also a ton of advancement in mathematical theorems. Advancements that eventually led to the first universe models discussed here, namely, the Big Bang and Steady-State Model, were created by Fred Hoyle, Thomas Gold, and Hermann Bondi in 1948.
General Relativity
Albert Einstein is one who at first rejected a temporal universe and thought an expanding universe was absurd and unrealistic. In 1905, he created his theory of Special Relativity, which states that distance and time are relative in the sense that two observers moving at different velocities perceive time and space differently. The effects are only noticeably felt at near light speeds. The theory states that the perception of time, depending on the speed of the observer relative to an object, is known as time dilation. Time dilation has been confirmed in experiments using atomic clocks, where one is on the ground, and the other in a plane flying (http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/airtim.html#c1). Einstein's Special Theory shows that measurements of space and time are ultimately linked since a measurement of space also depends on how fast you move over a period of time, and your experience of time depends on how fast you travel through space.
Throughout the creation of SR, Einstein realised that it implies that space and time are linked, birthing a new physical entity, spacetime. Spacetime combines the three spatial dimensions (X, Y, and Z) with the time variable (T) in a four-dimensional continuum (X, Y, Z, CT) where C represents the speed of light. With spacetime being the fundamental component of his theory of General Relativity (1915), which describes gravitation in relation to mass and spacetime, he envisioned gravity as a geometric property of spacetime, one like a fabric that objects possessing mass warp with their presence. A massive body will warp the multidimensional fabric of spacetime around it, creating a depression in it. The more mass, the more the fabric will warp; and with more mass, the deeper the warp, and the stronger the gravitational force. A smaller body will travel the curved spacetime, essentially "falling" into the gravitation of the larger body. In essence, "Space tells matter where and how to move, and matter tells space where and how to curve."
It wasn't long before the theory had an opportunity to be tested. Not only did it properly account for an unexplained shift in Mercury's orbit, but it was also put on full display in an experiment run in 1919. Sir Author Eddington used an eclipse on May 9, 1919, to test the theory of massive bodies warping spacetime. He observed the light passing by the sun during this solar eclipse. If GR held, then there should be a star of known position in a different position due to its light bending around the sun from the curved spacetime (See below).
By knowing the position of a star, and observing its position in a different location close to the sun than predicted, this offered evidence that space was bent around the sun, making it look like the star was in a different position while the light actually bent around the sun. This also meant that the laws of General Relativity are true in all locations of the universe.
Einstein realized that all mass in the universe, if no counter-acting force were present, would cause a gravitational effect throughout, and over time would cause all the matter in the universe to congeal in one single area. As each massive body exerts a gravitational force on the others, the matter in the universe would eventually blob together at a single point. Isaac Newton posited an infinite amount of matter that was equally distributed throughout an infinite space to allow for this balance. But Einstein's case was vastly different because his theory posited that all matter bent space itself, so that if the universe consisted of an infinite amount of matter, massive bodies would still cause the space to curve in on itself, eventually meeting the same blob-point end. He realized that if gravity were the only force acting, then all the matter would congeal and spacetime would contract on itself, creating a "big crunch," but nothing of the like has happened.
In response to this issue, he posited an outward pushing force of expansion to account for all the space observed between galaxies (massive bodies). This physical constant was called the "Cosmological Constant".
The Static Universe
In his 1917 paper titled “Cosmological Considerations in the General Theory of Relativity,” he introduced the cosmological constant to explain the constant active repulsive force that countered the effects of gravity from massive bodies. In it, he argued that his equations allowed for a static universe if some assumptions were made. (1) The Curvature of the universe was positive (meaning like the surface of a sphere), and (2) his equations include the additional cosmological constant with a specific value to perfectly balance the gravitational force, not allowing the universe to expand or contract. He assigned a value so precise to ensure that the effects of gravity and repulsion were perfectly balanced (we will see how this value is precise shortly). His choice for the value had no empirical justification; it followed from his assumption of an eternal universe. Creating the constant with a set value allowed him to keep the universe static and eternal.
Then, in 1922, the Russian physicist Aleksandr Friedmann solved Einstein's field equations, but with terms that enabled the radius of the universe to change with time. The field equations allow physicists to describe the differences in the spatial configuration of the universe that would be derived from different possible distributions of mass-energy from the start. His assumption followed from Einstein's theory of gravity, mainly that massive bodies cause space to contract and change over time. Although he never attempted to explain whether or not the universe was expanding, contracting, or static (only that the status of the universe was different depending on the value of the cosmological constant), he showed that practically all values except the one Einstein chose implied a dynamic universe (dynamic here means that it changes with time, or expands/contracts). This further implied that Einstein's choice of the value made his universe ultimately fine-tuned. But even with Einstein's value, his model implied a very unstable universe that was subject to even the slightest disturbance. But in an eternal universe, such disturbances are bound to happen, and if the universe is infinitely old, those disturbances had an infinitely long time in the past to occur.
Combining Evidence with Theory
Five years later (1927), Belgian priest and physicist Georges Lemaitre produced the same equations that Friedmann had made, but he combined his equations with observational evidence from Vesto Slipher and Edwin Hubble. He used Slipher's Doppler shift observations of distant galaxies and correlated them with Hubble's measurements of other galaxies. With this, he implied that galaxies were receding from us, and that the further away a galaxy was, the faster its recessional velocity was. Lemaitre formulated this relationship before Hubble, although Hubble later did so with more data than Lemaitre. This recessional relationship suggested a spherical expansion in all directions.
Lemaitre not only used mathematics to suggest that space changes over time, but he also cited observational evidence to show that space is changing; in fact, it's expanding! His model implied that not just galaxies were moving away from us in space, but that space itself was expanding, and that it must have started at a single point that he called the "Primeval Atom".
“At some point in the past… the distance between neighboring galaxies must have been zero. (Hawking, A Brief History of Time, Pg 49)"
Einstein had a Bone to Pick
Einstein expressed disagreement with Friedmann and Lemaitre's solutions to his field equations, at first claiming them as not actually satisfy the equations. He saw Lameître's hypothesis as "inspired by the Christian dogma of creation, and totally unjustified from the physical point of view. (Luminet, Lameître’s Big Bang, P 10)." But his mind began to slowly change, and in 1927, he saw the redshift evidence from Lameître in a cab ride at the Solvay Conference. In 1930, Sir Arthur Eddington also informed him of the observational data, introducing him to Hubble's 1929 paper establishing Hubble's Constant during a visit to the University of Cambridge. Eddington also showed him how the value of the cosmological constant and the curvature of the universe needed to be extremely fine-tuned for the universe not to expand forever or result in a "big crunch."
In 1931, Einstein visited Hubble's Mt. Wilson 2.5-m telescope, where he saw first-hand the evidence of the expanding universe. After this visitation, he publicly announced his recognition of a cosmological beginning. He later admitted that his choice of a static universe was "the biggest blunder of my life."
The Steady-State Model
During the 20th century, cosmologists were creating alternative theories to the Big Bang. Most of which were made for the sole purpose of philosophical reasons that came from a materialist worldview. An infinitely old universe would completely annihilate the requirement of understanding its origins. They needed an eternal universe because the Big Bang theory implied that the universe was caused by something outside of space, time, and mass-energy, and naturalism had nothing to posit except space, time, and mass-energy. In 1948, Fred Hoyle, Thomas Gold, and Hermann Bondi created the Steady-State Model to explain the expansion without implying a beginning. Since red shift evidence supported universe expansion, they posited that the universe would endlessly double in size, and since doubling an infinite generates another infinite, there would be no change to the measurable dimensions of the universe (Meyer, Return of the God Hypothesis, Pg 98). If the universe has some field that endlessly generates new mass-energy into the expanding space, keeping matter equally distributed, it would eliminate the need for a beginning.
But where does this matter originate? Hoyle postulated a creation field (C-field) that created new matter. His justification was arbitrarily creating a new fundamental physical principle that the universe must always remain at a constant density. The C-field was seen as a vast reservoir of negative energy that existed alongside the eternal, self-existent universe.
Here Lies "Steady-State Model": The Cosmic Background Radiation
For the remainder of the early 60s, the Steady-state Model remained the favored theory for most physicists. Then, at the halfway mark, in 1965, Arno Penzias and Robert Wilson made a discovery that killed it. The Big Bang theory predicted a low-energy background radiation throughout the entire universe. This was due to the extremely dense mass-energy shortly after the beginning of the universe would have radiated electromagnetic energy throughout the universe at that stage, essentially leaving behind a flash from the big bang that would still be dissipating.
In 1948, Robert Herman and Ralph Alpher predicted this radiation: As the universe expanded and cooled to the point that electrons could attain stable orbits around protons and neutrons, allowing for light to freely travel without being redirected by electrons in the Plasma State. This would have bathed the early universe in light traveling in every direction. The continuing expansion of space would have stretched this light's wavelength to the far end of the electromagnetic spectrum, namely the microwave portion at 1mm wavelength. They also calculated that the temperature from the blackbody of the mass-energy from the plasma state based on the Big Bang model is only a few kelvin above absolute zero in the present, at 5 kelvin. They did this by dividing the temperature of the universe at that time when light could first travel, 3000, by the expansion rate of the universe at 550 times. This gave them a temperature for the cosmic background radiation today at about 5 kelvin (Myer, Return of the God Hypothesis, Pg 100-101).
In 1964, Penzias and Wilson were unable to get rid of some radio static in their antenna at the Bell Telephone Laboratories in New Jersey. They had this constant hum that was in every part of the night sky. They had no way to identify and avoid the low-frequency hum. A physicist proposed that they were not experiencing an antenna fault, but detecting residual background radiation from the universe's beginning. They discovered the Big Bang Model predicted Cosmic Background radiation! They won the Nobel Prize in 1978 for their discovery. There were then later confirmations of the radiation from the Cosmic Background Explorer Satellite launched in 1989 and the Planck Space Observatory launched in 2009. For many scientists, this evidence confirmed the belief in a temporal universe.
J. Warner Wallace gives us a helpful analogy for understanding the Cosmic Background Radiation:
“We employed a “flash-bang” grenade in nearly all these SWAT entries. The grenades are designed, of course, to 'flash' and 'bang'; they make a lot of noise, light, and heat. We typically threw a grenade in the room where the suspect was barricaded (usually through a window). When the grenade hit the ground, it exploded violently, lighting the room, deafening the suspect, and filling the space with debris and heat. In that instant, as the suspect was distracted, our team came in from the opposite corner. Flashbangs are excellent distraction devices because they leave a lingering impact in the space where they are deployed. (Wallace, God’s Crime Scene, Pg 36)"
If the universe began, expanding from an initial state of tremendous heat, density, expansion, and extreme spacetime curvature, we should expect to find evidence of the temperature that experienced expansion in the form of the low-temperature blackbody predicted by Herman and Alpher. Steady-state proponents soon admitted that their model had no prediction of this detected energy, but there were more issues. The Steady-state Model predicted that galaxies should be observed in various ages, from young to old, but no such young galaxies have ever been observed. By the 1970s, the theory was dead in the water and buried with a gravestone that reads, "Here Lies 'Steady-State Model'".
The Oscillating-Universe Model
After the demise of the Steady-state Model, physicists began proposing an Oscillating-universe Model as another alternative to the Big Bang. This theory proposed a universe that would expand, decelerate expansion, shrink under gravitational force, and then, by some unknown mechanism, begin its expansion again on repeat for eternity. Now, we have three competing models for the state of the universe.
The Big Bang: The universe began, and it is expanding.
The Steady-state: The universe is expanding eternally, but also eternally creating new matter.
The Oscillating-Universe: The universe goes through an infinite number of cycles of expansion and contraction.
The death of the Oscillating-Universe Model
Proponents of this theory were ultimately unable to create a mechanism that would cause the expansion to restart after gravitational collapse. Nowadays, there are "bounce theories" that invoke mechanisms with absolutely no empirical or epistemic justification. They also violate the null energy condition, implying instabilities from each bounce (Diana Battefield and Patrick Peter, A Critical Review of Classic Bouncing Cosmologies, Physics Report (Elsevier B.V., April 1, 2015); cited in Myer, Return of the God Hypothesis, Pg 467-468 n.53). It also ran into difficulties with the 2nd Law of Thermodynamics. Alan Guth showed that with each cycle of oscillation, the entropy of matter and energy would increase. This results in less usable energy available to perform work with each cycle, and causes longer and longer periods of oscillation from the inhomogeneities in mass-energy distributions, affecting the efficiency of the gravitational force to cause contraction as expansion decelerates. This means each previous oscillation would be shorter and shorter in duration, and it cannot decrease ad infinitum. You're still left with the implications of a beginning.
To make matters worse, as the universe expands and contracts more and more for an infinite time, all the energy in the universe would reach thermodynamic equilibrium and be completely randomized, leaving only heat energy and none to perform work, known as the "Heat Death". Modern measurements have discovered that the universe's mass density is actually less than the needed density to overcome expansion and cause it to stop, laying another bullet in our buddy Osci. The expansion may also be the result of what physicists call today, dark energy, which seems to permeate all space and exert outward pressure on it.
One of the Last Hurdles
For the most part, the Big Bang seemed to have won the battle, coming out as the favored theory for the origin of the universe. Also, for the most part, it seemed to have one last big issue. For galaxies to begin to form, the mass-energy after the Big Bang must have had slight fluctuations in its density. This flowed from the observed space between galaxies. These fluctuations would affect the background radiation, as different densities of mass-energy would exhibit different wavelengths emitted from the different regions of the energy in the universe. This is why the Big Bang implies slight variations in the cosmic background radiation. In 1989, when NASA launched the Cosmic Background Radiation Explorer Satellite, did they measure the background radiation, suspended above the noisy atmosphere humanity dominated, and discover the predicted variations in its density that previous ground scans were unable to detect. This evidence cleared one of the last issues with the Big Bang model, solidifying it as the favored theory of a temporal universe.
The Singularity Theorems
In the 1960s, while Stephen Hawking was conducting his PhD research, he ran into the work of a physicist, Roger Penrose. Penrose was working out the physics of blackholes, areas where the mass is so densely packed by gravitational force that not even light can escape its effects. The mass of a black hole is so strong that it curves the spacetime into an enclosed region of space, with such gravitational effects that not even light can escape.
Fun Fact: Depictions of black holes display a black spherical center. This black sphere is not the actual black hole itself, but a region called the event horizon. This is the point around the blackhole where the gravitational attraction is so strong that light cannot escape, hence the entire region appears black, because no light can escape that region. For us to see the blackhole itself, light would have to bounce off its surface, but if no light can escape the event horizon, then all we can see is a black area of space due to the absence of light reflection beyond that point.
Hawking began analyzing his work and realized something about the past status of the universe. At every single point in the past, the mass of the universe would become smaller and smaller. Extrapolating further back, the curvature of space would approach an infinitely tight spatial volume that corresponds to zero volume. This zero-volume area is called a singularity, where the laws of physics break down, and where the universe would have begun its initial expansion. In his PhD thesis, Hawking had a chapter about the implications of General relativity and the expanding universe, also providing mathematical proof for the singularity at the beginning of the universe. He showed that any time or light-like path between 2 points in the expanding universe would necessarily terminate at some finite point in the past (Hawking, Properties of Expanding Universes, Pg 105).
During the late 60s and 70s, Hawking, Penrose, and George Ellis published some papers that made implications for the beginning og the universe from General Relativity. Their solutions to Einstein's field equations implied a singularity at the beginning of the universe, where the matter density and curvature would approach an infinite value.
The Hawking-Penrose-Ellis Model
Friedmann's previous solutions for a dynamic universe also implied a singularity at the beginning of the universe, but he did so by assuming the mass-energy distribution was completely homogeneous; in other words, the distribution of mass-energy was the same in all directions, and looked the same in all directions. But for galaxies to form, the initial distribution needed slight differences in its density. Then came the big three. Hawking, Penrose, and Ellis solved Einstein's field equations without assuming perfect homogeneity of mass-energy distribution. In doing so, they showed that given General Relativity, the universe began in a spacetime singularity.
As the universe expands, space flattens, and the curvature approaches zero; but in the reverse direction of time, the curvature increases, and as the distances between any 2 points also decrease, the curvature approaches an infinite value, and the distance between any 2 points approaches zero. Hence, the infinite curvature corresponds to zero spatial volume. Also, if the curvature of space approaches an infinite value, and the volume approaches zero, time would approach a zero value too.
How Much can we put into Where and When?
In 1978, Paul Davies described the spacetime singularity like this:
“If we extrapolate this prediction to its extreme, we reach a point when all distances in the universe have shrunk to zero. An initial cosmological singularity therefore forms a past temporal extremity to the universe. We cannot continue physical reasoning, or even the concept of spacetime, through such an extremity. For this reason most cosmologists think of the initial singularity as the beginning of the universe. On this view the big bang represents the creation event; the creation not only of all the matter and energy in the universe, but also of space-time itself. (Davies, Spacetime Singularities in Cosmology, 78-79)"
An infinitely tight space corresponds to zero spatial volume. The singularity theorems do not allow one to posit prior mass-energy or gravitational fields as an eternal entity since neither space nor time existed beforehand. It implies that energy and matter first arose at the beginning, along with space and time, although the actual point of creation is not described by current physics.
Inflationary Cosmology
During the 1980s, Alan Guth, Andrei Linde, and Paul Steinhardt developed a theory they called Inflationary Cosmology. Initially created to explain the homogeneity of mass-energy in the universe. It posits that soon after the Big Bang, the universe experienced a short, rapid expansion due to negative gravitational energy from a proposed inflaton field. It asserted that space rapidly expanded within fractions of a second after the Big Bang for a brief period of time (Alan Guth, Inflationary Universe).
Due to Quantum Field theory, many thought this field would be subject to quantum fluctuations, random fluctuations in its local energy density that would necessarily produce causally separate regions of space called bubble universes. After an expansion of space occurs, a quantum fluctuation causes it to decay locally and create a bubble universe, but since the field itself is eternally expanding, the bubble universes will continue to expand slightly and produce other regions in the field for other universes to inhabit as the fluctuations cause other regions to decay. This form of the theory is called Eternal Chaotic Inflation.
Eternal Chaotic Inflationary Violations
Proponents imagined the inflaton field being effective eternally into the past as well as into the future, creating an infinite array of bubble universes. Since the space outside the universes continues to expand faster than the bubble universes, they practically never make contact with each other and are thus undetectable from within one of them. Inflationary cosmological models all affirm quantum fluctuations as the prime mechanism to produce universes, but these models also include violations of various energy conditions required for singularity theorems to hold. Some quantum fluctuations would result in negative mass-energy densities for universes, which violates the Strong Energy Condition of General Relativity.
But Why Inflation?
The inflationary theory was first created to explain the homogeneity of the universe. This means that the universe has roughly the same matter distribution in all locations, mainly from the uniform temperature of the cosmic background radiation, which exhibits fluctuations so faint as to 1 part in 100,000 (LAMBDA - Cosmic Background Explorer). This was only an issue for the Big Bang model unless very finely tuned initial conditions were posited. Some people are misinformed that inflationary theory is required for the Big Bang model, but it can be explained by the Big Bang by postulating that the universe had nearly perfect uniformity in temperature and mass-energy distribution in the plasma state. But inflationary cosmologists do not attempt to explain homogeneity on initial conditions, as that would beg intelligent design of the universe. Instead, it postulates an early, rapid rate of expansion that smoothed out the distribution via an exponentially fast rate and a sudden stop at just the right time. Because of this, any remnants of the beginning of the universe would have been pushed far beyond the edge of the observable universe.
This expansion explained the observed flatness of the universe. Flatness means that space would have no curvature, so that two parallel lines would never converge or diverge, but remain next to each other. Our universe is relatively flat because its expansion has barely overcome the gravitational attraction produced by the mass-energy density. Today, physicists believe our universe has a mass density slightly lower than the critical mass required to cause gravity to overcome expansion and stop it. Nonetheless, gravity would still cause the universe to be slightly curved, just so that any small section of it would seem relatively flat (like a small section of land on the Earth). Inflation also seemed to explain the absence of Monopoles, particles that would act as magnets but with only one pole instead of two. How so? By claiming inflation pushed the evidence far beyond an observable distance.
The BGV Theorem, and the Death of Eternal Inflationary Cosmology
By the 90s, Inflationary Cosmology dominated the fields. It was the best model for the origin of the universe, and nobody could make a refutation to it. But then came a group that created just that, a theory that led to another proof of the temporal universe. The best part is, it holds even if the inflationary theory is correct.
The popularity of inflationary cosmology motivated physicists Arvind Borde and Alexander Vilenkin to attempt to see what inflation implied about the universe. If the universe really could be "past eternal". They were later joined by Alan Guth, and soon came to a sobering conclusion. Instead of attempting based on General Relativity, they did so on the grounds of Special Relativity. In 2003, Borde, Guth, and Vilenkin created a theory for the beginning of the universe that did not lean on any energy conditions or singularities.
“A remarkable thing about this theorem is its swapping generality. We made no assumptions about the material content of the universe. We did not even assume that gravity is described by Einstein’s equations. So, if Einstein's gravity requires some modification, our conclusion will still hold. The only assumption that we made was that the expansion rate of the universe never gets below some nonzero value, no matter how small. (Vilenkin, Many Worlds in One, Pg 175)"
The BGV Theorem states that "any universe that is on average expanding is past incomplete. Before I explain the theory, let me sum it up in simple terms for the layman. Simply, the theory states that if any universe is expanding, as time is extrapolated backward, all matter and energy within the expansion will eventually reach a velocity limit, the speed of light, marking the beginning of the expansion because it would be impossible to extrapolate back any further.
The BGV Theorem
If a spaceship were moving towards Earth, it would appear to move more slowly than it would if the universe were not expanding. If the spaceship continues to fly at a constant velocity, the spaceship will appear to be moving slower and slower as time progresses due to the space around the spaceship expanding at a faster and faster rate, and the space between the ship and Earth expanding. For example, on an expanding balloon, as objects on its surface draw further and further apart, they recede faster and faster from each other as the surface of the balloon grows. As we extrapolate time backward, the velocity of the expansion of space will decrease around the ship, resulting in the apparent velocity from Earth observed as increasing (due to the space around and between contracting). The recessional velocity of space would have been greater in the past. This means that as time is extrapolated back, the apparent velocity of any object increases; eventually, this velocity would reach the speed of light, the universal speed limit for anything containing mass. At this point, no back extrapolations could continue, implying that the universe must have had a beginning to its expansion.
To sum it up in other words, in an expanding universe, the further one follows the path of an object back in time, the greater its apparent velocity would have been relative to an observer. But according to Special Relativity, an object in any frame of reference cannot exceed the speed of light. So if we extrapolate time back, objects relative to an observer would have reached this limit at some point in the past, at which point no further back extrapolations can be done. This would necessarily represent the beginning of the path of any matter or energy and mark the beginning of expansion.
The Eternal Burp
Borde, Guth, and Vilenkin (Who the BGV Theorem is named after) showed the world that all cosmological models featuring an expanding universe, whether that be the multiverse, inflation, steady-state, or oscillating models, are subject to the BGV theorem.
“With the proof now in place, cosmologists can no longer hide behind the possibility of a past-eternal universe. There is no escape; they have to face the problem of a cosmic beginning. (Vilenkin, Many Worlds in One, Pg 176, Quoted in Meyer, Return of the God Hypothesis, Pg 128)"
Nowadays, cosmologists look towards quantum cosmological models to explain the eternal universe, but that is a topic for the coming articles. We shall discuss in more detail Inflationary Cosmology, String Theory, and finally Quantum theories for the origin of the universe, and whether they can claim an eternal universe.
The Big Size Limitation
Now, before we conclude, I must mention one last very important fact before we continue to other areas. All singularity models presuppose General Relativity as the most accurate theory for describing gravity. But general Relativity poses one issue: these models can really only go backwards so far. As far as when the universe had a spacetime curvature of 10-12 to 10-33 cm in diameter. At this unimaginably small size, General Relativity breaks down, and another theory has to be used, called Quantum Physics. At this small size, quantum phenomena dominate, and cosmologists have to develop models analogous to phenomena found in quantum physics to explain the state of the universe before this period, before the singularity.
Philosophical Evidence: Infinite Regress
As mentioned briefly in the previous article, there are some philosophical issues with an eternally existent universe. From here, I refer you to the discussion of potential and actual infinites from the previous article on the Kalam Cosmological argument. Potential infinities are one thing, that being an ideal limit to a continuous set. Like a man counting from one and continuing to do so for an infinite time. He will count and approach that ideal limit of infinity, but he will never actually reach it. Now we come to actual infinites, that being infinites that actually exist. An example of an actual infinite is the number of numbers in the whole number set. There is an actually infinite number of numbers in the set, but actual infinites existing in the material, natural world is an entirely different thing. Actual infinities result in absurdities.
If I have a chest full of an infinite number of lollipops, and I have to give away one lollipop to every person on Earth, how many would I have left? An infinite number of lollipops are still in my chest. Moreover, if the candy government taxes 33% of my lollipops, how many do I have left after 1/3 is removed? Still, an infinite number remains. Here's a better example, in the set of whole numbers, which has an infinite number of numbers in it, how many odd numbers are contained in it? An infinite number of odd numbers are within the whole number set. How many prime numbers are there? An infinite number of prime numbers. J. Warner Wallace offers a useful explanation: you are about to begin a race, and before the race begins, you are told to move your starting line back a foot. Before the race starts again, you are told to move your line back a foot. If this continues forever, will you ever reach the finish line? Without a beginning, you will never have an opportunity to finish. If the universe never began, today would never terminate.
Thermodynamic Evidence of a Beginning
Not only does an infinitely old universe result in logical absurdities, but the idea also violates thermodynamics. Namely, the second law of thermodynamics. The quantity of energy in a closed, isolated system remains constant while the amount of usable energy to perform work deteriorates as time advances. The amount of entropy in a system will increase over time, or disorder. This means that if the universe were infinitely old, then the amount of usable energy would have run out an infinitely long time ago, which is an absurd thought, and has obviously not happened. Better yet, unless fed from an outside source, the energy in the universe would even out, be randomized, and reach equilibrium in temperature, energy, and disorder.
Imagine you stumble across a cabin while hiking with your friends. You guys walk up the porch steps (what remains of them) and approach the door. The door is just on its hinges, and as your buddy knocks it over, you all see an old, broken-down kitchen with a table. On the table is a cup of hot tea, and on the floor is a wind-up easter chick, still bounding and ticking about. You would almost immediately deduce that the tea was just recently made, and the toy was just wound up by another person, before you knocked the door off its hinges. The fact that the universe still contains usable energy and is not a large sludge of heat hints at the reality that the universe had a beginning. Moreover, models like the Steady-state Model violate the first law of thermodynamics, which states that mass-energy is not being created, nor annihilated, but transferring its form and usability.
Conclusion
As we have seen, major developments in astronomy, cosmology, and mathematics all offered hard evidence that the universe was, in fact, not eternal, nor infinite in time or space. With the spacetime curvature of a singularity approaching an infinite value corresponding to zero spatial volume, the universe essentially did begin at this point, with matter and energy arising alongside space and time. For where can we put something if there's no space to put it? Indeed, if singularity theorems do not enable one to posit a material state prior to the singularity, then the cause of such cannot be within it. It seems, at least to me, that this cause must have been transcedent to space, time, and mass-energy. It must be a spaceless, timeless, self-existent, all-powerful, intelligent cause to be at least adequate to explain the universe in the first place! How can a material state exist before any material state? If the universe remained at this material state for an infinite age, why did it not cause a universe at any point before when it did if it existed in a material state that is causally adequate for the universe to come into existence for an infinite amount of time beforehand? Jeese! All of this infinity babble is making my brain cramp!
Moreover, the cause must also be personal, for reasons to be stated in a future article, but for now, I can say that to go from a state of non-creation to creation requires a choice to be made. And if there was a personal mind before the universe, it very well could have chosen to create this universe that we see today. Might I also say that this does not really get us to the Christian God; rather, that comes with a thorough investigation of the historical reliability of the crucifixion and resurrection of Jesus Christ. At least for now, we can confidently say, some personal cause with the attributes of the Biblical God is causally adequate to explain the universe we observe today.
"In the beginning, God created the heavens and the earth. (Genesis 1:1)"
"And when you look up to the sky and see the sun, the moon, and the stars—all the heavenly array—do not be enticed into bowing down to them and worshiping things the LORD your God has apportioned to all the nations under heaven. (Deuteronomy 4:19)"
"He sits enthroned above the circle of the earth, and its people are like grasshoppers. He stretches out the heavens like a canopy, and spreads them out like a tent to live in. (Isaiah 40:22)"
"Behold, he is coming with clouds, and every eye will see him, even they who pierced him. And all the tribes of the earth will mourn because of him. Even so, Amen. (Revelation 1:7)"
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