Is time an eternity or does it have a beginning and end?
This question is very difficult to answer because current theories are only able to describe what happened after the beginning of our universe. In other words how the universe came about and whether there is any meaning to a “before” or “after” is unknown and perhaps unknowable. Therefore many believe it is not possible to determine if time began at the moment of its inception or if it had its beginnings in a previous epic.
The reason is because the most popular theories of its origin assume that it emerged from a singularity or one dimensional point and is expanding from the tremendously hot dense plasma environment associated with it. This Big Bang theory, as this concept has come to be called assumes the momentum generated by the heat of that environment is sustaining the expansion.
Unfortunately for those looking for an answer to the question as to the eternity of time, the laws of physics cannot be applied to a singularity therefore it is impossible to use them to understand what may have happened in the period before the universe was formed.
However this may not be true because using the currently accepted laws of physics one can project observations made in our present time backwards to the show that it may not have had its beginning in a singularity.
For example observations in “our time” tell us when a star supernova explodes it expels hot gas. However scientists know that a star existed before that event occurred because they can project the laws of physics governing the expanding hot gases backwards to define a period before it took place. In other words they can determine what existed before an event occurred such as a supernova by projecting their understanding the process that happened after it backwards to the period before it took place.
Yet there are many observations like those associated with the expanding gases of supernova that suggest that our universes expansion did not begin form a one dimensional point or a singularity as the Big Bang models assumes but from an extended three-dimensional volume of space.
The difference between a theoretical model based on these “real time” observations and the mathematical model supporting the existence of a singularity is because, as mentioned earlier science cannot project the laws of physics beyond a mathematically predicted singularity but can through a three-dimensional volume.
Therefore using a theoretical model based on observations of a three-dimensional environment means that science could predict the existence of time before the beginning of our universe by projecting the currently accepted laws of physics beyond the three-dimensional volume that it suggests its expansion began from.
For example one of the most fundament and verifiable observations in science is that the total quantity of energy/mass in a closed system is conserved and that it cannot be created or destroyed. Since, by definition our universe is a closed system according to its energy/mass cannot be created or destroyed in it.
Yet we know from observations the equation E=mc^2 defines the equivalence between mass and energy in an environment and since mass is associated with the attractive properties of gravity it also tells us the kinetic energy associated with the universe’s expansion also possess those attractive properties. Therefore the law of conservation of energy/mass tells us that in a closed system the creation of kinetic energy cannot exceed the gravitational energy associated with the total energy/mass in the universe.
However, not all of the energy of associated with the universe’s expansion is directed towards it because of the random motion of its energy/mass components. For example, observations indicate that some stars and galaxies are moving towards not away us. Therefore, not all of the energy present at the time of its origin is directed towards its expansion.
As mentioned earlier the law of conservation of energy/mass tells us that gravitational contractive properties of the universe’s energy/mass cannot exceed its kinetic energy equivalent at time the expansion of the universe began. However because some of the kinetic energy of its components is not directed towards its expansion the total gravitational contractive properties of its energy/mass must exceed the kinetic energy of its expansive components. Therefore, at some point in time the gravitation contractive potential of its energy/mass must exceed the kinetic energy of its expansion because as just mentioned not all of its kinetic energy is directed towards its expansion. Therefore at that point, in time the universe will have to enter a contractive phase.
Some may disagree by saying that as the universe expands its energy is spread out over a larger volume so after a while it just vanishes so to speak or as some like to say the universe experiences a heat death. However Einstein theories do not permit energy to just disappear or “die”. It unequivocally tells us that if the kinetic energy content in a closed environment decreases as it cools the mass content of that environment must increase irrespective of the volume of that environment. Therefore because by definition the universe is a closed system one must assume that any reduction in its overall energy content of the universe including its heat energy must be must be compensated for by an increase in its total attractive gravitational mass content.
Others would disagree because recent observations suggest that a force called Dark energy is causing the expansion of the universe accelerate. Therefore they believe that its expansion will continue forever. However, as was shown in the article “Dark Energy and the evolution of the universe” if one assumes the law of conservation of mass/energy is valid, as we have done here than the gravitational contractive properties of its mass equivalent will eventually exceed its expansive energy associated with dark energy and therefore the universe must at some time in the future enter a contractive phase.
We also know from observations that heat is generated when we compress a gas and that this heat creates pressure that opposes further contractions.
Similarly the contraction of the universe will create heat which will oppose its further contractions.
Therefore the velocity of contraction of our universe will increase until the momentum of the galaxies, planets, components of the universe equals the radiation pressure generated by the heat of its contraction.
At this point in time the total kinetic energy of the collapsing universe would be equal to the radiation pressure associated with the heat of its collapse. From this point on its contraction will be maintained by the momentum associated with the remaining mass component of the universe.
However, after a certain point in time the radiation pressure generated by it will become great enough to ionize its mass component and to cause it to reexpand.
This will result in the universe entering an expansive phase and going through another age of recombination when the comic background radiation was emitted and the recreation of the particle mass that latter is responsible for the development of stars and galaxies. This is because the expansive forces associated with the radiation pressure caused by its collapse will exceed the contractive forces associated with the remaining mass of the universe. The reason it will experience an age of recombination as it passes through each cycle is because the heat of its collapse would be great enough to completely ionize all forms of matter.
However, at some point in time the contraction phase will begin again because as mentioned earlier its kinetic energy cannot exceed the gravitational energy associated with the total mass/energy in the universe.
Since the universe is a closed system, the amplitude of the expansions and contractions will remain constant because the law of conservation of mass/energy dictates the total mass and energy in a closed system remains constant.
This results in the universe experiencing in a never-ending cycle of expansions and contractions of equal magnitudes.
As mentioned earlier many cosmologists do not accept the cyclical scenario of expansion and contractions because they believe a collapsing universe would end in the formation of a singularity similar to the ones found in a black hole and therefore, it could not re-expand.
However, according to the first law of thermodynamic the universe would have to begin expanding before it reached a singularity because that law states that energy in an isolated system can neither be created nor destroyed
Therefore because the universe is by definition an isolated system; the energy generated by its gravitational collapse cannot be radiated to another volume but must remain within it. This means the radiation pressure exerted by its collapse must eventually exceed momentum of its contraction and the universe would have to enter an expansion phase because its momentum will carry it beyond the equilibrium point were the radiation pressure is greater that the momentum of its mass. This will cause the mass/energy of the universe to oscillate around a point in space.
This would be analogous to the how momentum of a mass on a spring causes it spring to stretch beyond its equilibrium point resulting it osculating around it.
There can be no other interoperation if one assumes the validity of the first law of thermodynamics which states that the total energy of the universe is defined of mass and the momentum of its components. Therefore, when one decreases the other must increase and the universe must oscillate around a point in space if it does enter a contraction phase.
The reason a singularity can form in black hole is because it is not an isolate system therefore the thermal radiation associated with its collapse can be radiated into the surrounding space. Therefore, its collapse can continue because momentum of its mass can exceed the radiation pressure cause by its collapse in the volume surrounding a black hole.
As mentioned earlier the heat generated by the collapse of the universe would raise the temperature to a point where electrons would be strip off all matter and it would become ionized, making it opaque to radiation. It would remain that way until it entered the expansion phase and cooled enough to allow matter to recapture and hold on to them. This Age of Recombination, as cosmologists like to call it is when the Cosmic Background Radiation was emitted.
One could quantify this scenario by using the first law of thermodynamics to calculate the temperature of the universe when the radiation pressure generated by the gravitational collapse of the universe exceeds the momentum of that collapse and see if it is great enough to cause another with the Age or Recombination as it must to account for the observed properties of the Cosmic back ground radiation.
As mentioned earlier using the above theoretical model scientists can predict the existence of time before the beginning and after the end of our present universe by projecting the currently accepted laws of physics beyond the three-dimensional volume that it suggests it began and will end in.
However this also tells us that the time we experienced is an integral part of our universe because one can trace its origins through the laws of physics to previous and future epics of universe creation.
But it also tells us that that time does not exist eternally to our universe because the laws of physics we use to define how it progresses from the past to the future cannot be exported to an environment outside of it.
Therefore, one cannot ask when or at what time these cycles of expansions or contractions began or will end because, as just mentioned the time we experience only exists in our universe.
This means we must consider the time we experience as eternal because there is no meaning to asking when those cycles of expansion and contractions began or will end with respect to the existence of our universe because they are part of it.
Later Jeff
Copyright 2012 Jeffrey O’Callaghan