This is a little play on words. The Big Bang theory holds that the evolution of the universe started with an infinitesimal packet of near infinite energy (termed a “singularity”) that suddenly expanded and continues to expand. If this is true, was it big? No, it was infinitesimally small. Did it go bang? No, it expanded. Space is a vacuum, and it is unable to transmit sound waves. Therefore, there were no sound waves to make a bang noise. Granted, I was not there since it took place 13.8 billion years ago, and you are certainly entitled to your own opinion. I am only jesting, but the description above of the Big Bang theory is what the scientific community holds to be responsible for the evolution of the universe.

What initiated the Big Bang’s expansion?

Throughout the theories of science, there appears to be a common thread based on well-observed physical phenomena regarding the behavior of energy. That common thread states that differences in temperature, pressure, and chemical potential always seek equilibrium if they are in an isolated physical system. For example, with time, a hot cup of coffee will cool to room temperature. This means it reaches equilibrium (balance, stability and sameness) with the temperature of the room, which is the isolated physical system in this example. Readers familiar with thermodynamics will instantly attribute this behavior of energy as following the second law of thermodynamics. However, the same law, worded differently, exists in numerous scientific contexts. In the interest of clarity, I am going to restate this law, describing the behavior of energy, in a way that makes it independent of scientific contexts. In a sense, it abstracts the essence of the contextual statements, and views applications of the law in various scientific contexts as specific cases. I am not the first physicist to undertake generalizing the second law of thermodynamics to make it independent of scientific contexts. However, I believe my proposed restatement provides a simple and comprehensive description of the laws that energy follows. For the sake of reference, I have termed my restatement the Minimum Energy Principle.

Energy in any form seeks stability at the lowest energy state possible, and will not transition to a new state unless acted on by another energy source.

Consider these two examples to illustrate the Minimum Energy Principle.

1)   Radioactive substances. Radioactive substances emit radiation until they are no longer radioactive (they become stable). However, by introducing other radioactive substances under the right conditions, they can transition to a new state. Indeed, if the proper radioactive elements combine under the right circumstances, the result can be an atomic explosion.

2)   A thermodynamic example. Consider a branding iron fresh from the fire. It emits thermal radiation until it reaches equilibrium with its surroundings. In other words, once a branding iron leaves the fire, it will start to cool by transferring energy to its surrounding. Eventually, it will be at the same temperature as its surroundings. (This illustrates the first part of the Minimum Energy Principle: Energy in any form seeks stability at the lowest energy state possible.) However, if we increase the temperature of the branding iron by placing it back in the fire, the branding iron will absorb energy until it again reaches equilibrium with the temperature of the fire. (This illustrates the second part of the Minimum Energy Principle: It transitions to this new state by being acted on by the fire. The fire acts as an energy source.)

The Minimum Energy Principle is consistent with the law of entropy. To understand this, we will need to discuss entropy. In classical thermodynamics, entropy is the energy unavailable for work in a thermodynamic process. For example, no machine is one hundred percent efficient in converting energy to work. A portion of the energy is always lost in the form of waste heat. An example is the miles per gallon achievable via your car engine, ignoring other factors such as the weight of the vehicle, its aerodynamic design, and other similar factors. Several car manufacturers are able to build highly efficient engines. However, no car manufacturer can build an engine that is one hundred percent efficient. As a result, a fraction of total energy is always lost, typically in the form of waste heat.

Entropy proceeds in one direction, and is a measure of the system’s disorder. Any increase in entropy implies an increase in disorder and an increase in stability. For example, the heat lost in a car engine is lost to the atmosphere, and is no longer usable to do work. The heat lost is adding to the disorder of the universe, and is a measure of entropy. Oddly, though, the lost heat is completely stable.

In a given system, entropy is either constant or increasing, depending on the flow of energy. If the system is isolated, and has no energy flow, the entropy remains constant. If the system is undergoing an energy change, such as ice melting in a glass of water, the entropy is increasing. When the ice completely melts, and the system reaches equilibrium with its surrounding, it is stable. This has a significant implication. Entropy is constantly increasing in the universe since everything in the universe is undergoing energy change. In theory, the entropy of the universe will eventually maximize, and all reality will be lost to heat. The universe will be completely stable and static. I have termed this the “entropy apocalypse.” (Some physicists term this “heat death.”) I know I am being a little dramatic here, but most of the scientific community believes the entropy (disorder) of the universe is increasing. Eventually, all energy in the universe will be stable and unusable, all change will cease to occur, and the universe will have reached the entropy apocalypse.

Based on the above discussion of entropy, we can argue that entropy seeks to maximize and, therefore, reduce energy to the lowest state possible. This is why I stated that the Minimum Energy Principle, which asserts that energy seeks the lowest state possible, is consistent with law of entropy.

How does this help us understand what made the Big Bang go bang? The Minimum Energy Principle, along with our understanding of the behavior of entropy, makes answering this question relatively easy. The scientific community agrees that the Big Bang started with a point of infinite energy, at the instant prior to the expansion. From the Minimum Energy Principle, we know “Energy in any form seeks stability at the lowest energy state possible and will not transition to a new state unless acted on by another energy source.” Since we know it went “bang,” we can make three deductions regarding the infinitely dense-energy point. First, it was not stable. Second, it was not in the lowest energy state possible. Third, the entropy of the infinitely dense-energy point was at its lowest state possible, which science terms the “ground-state entropy.” These three conditions set the stage for the Minimum Energy Principle and the laws of entropy to initiate the Big Bang.

By the very nature of “playing the tape” of the expanding universe back to discover its origin, namely the Big Bang, we can conclude a highly dense energy state. It will be a highly dense energy state because we are going to take all the energy that expanded from the Big Bang, and cause it to contract. As it contracts, the universe grows smaller and more energy-dense. At the end of this process, we have a highly dense energy state. I think of it as a point, potentially without dimensions, but with near-infinite energy. This view is widely held by the scientific community. If it is true, all logic causes us to conclude it was an infinitely excited energy state, and we would have every reason to question its stability—and to believe it was at the “ground-state” entropy (the lowest entropy state possible).

Our observations of unstable energy systems in the laboratory suggest that as soon as the point of infinite energy came to exist, it had to seek stability at a lower energy level. The Big Bang was a form of energy dilution. In the process of lowering the energy, it increased the entropy of the universe. Once again, we see the Minimum Energy Principle and the law of entropy acting in concert.

How long did the infinitely dense-energy point exist? No one really knows. However, we can approach an answer by understanding more about time.

Discussing the Big Bang in terms of time, as we typically understand time, is difficult. It will not do any good to look at your watch or think in small fractions of a second. Stop-motion photography will not work this time. Those times are infinitely large compared to Planck time (~ 10-43 seconds, which is a one divided by a one with forty-three zero after it). Theoretically, Planck time is the smallest time-frame we will ever be able to measure. So far, we have not even come close to measuring Planck time. The best measurement of time to date is of the order 10-18 seconds.

What is so significant about Planck time? The fundamental constants of the universe formulate Planck time, not arbitrary units. According to the laws of physics, we would be unable to measure “change” if the time interval were shorter that Planck time. In other words, Planck time is the shortest interval we humans are able to measure, or even comprehend change to occur. Scientifically, it can be argued that no time interval is shorter that Planck time. Thus, the most rapid change can only occur in concert with Planck time, and no faster. Therefore, when we discuss the initiation of the Big Bang, the smallest time interval we can consider is Planck time.

The whole notion of Planck time, and its relationship to the Big Bang, begs another question. Did time always exist? Most physicists say NO. Time requires energy changes, and that did not occur until the instant of the Big Bang. Stephen Hawking, one of the world’s most prominent physicists and cosmologists, is on record that he believes time started with the Big Bang. Dr. Hawking asserts that if there was a time before the Big Bang, we have no way to access the information. From this standpoint, it is reasonable to believe time for our universe started with the Big Bang. This is our reality. This is consistent with Occam’s razor, which states the simplest explanation is the most plausible one (until new data to the contrary is available). For our universe, the Big Bang started the clock ticking, with the smallest tick being Planck time.

We are finally in a position to answer the crucial question: What made the big bang go bang?

The Big Bang followed the Minimum Energy Principle, “Energy in any form seeks stability at the lowest energy state possible, and will not transition to a new state unless acted on by another energy source.” The infinitely dense energy point, which science terms a “singularity,” sought stability at the lowest energy state possible. Being infinitely energy-dense, implies instability and minimum entropy (ground-state entropy). Thus, it required dilution to become stable, which caused entropy to increase. The dilution came in the form of the “Big Bang.” Since we were dealing with an unstable infinitely energy-dense point, it is reasonable to assert the Big Bang went bang at the instant of existence. The instant of existence would correlate to the smallest time interval science can conceive, the Planck time. This process is continuing today as space continues its accelerated expansion. 

Source: Unraveling the Universe’s Mysteries (2012), Louis A. Del Monte, available on