The first law of thermodynamics is the familiar conservation of energy principle. That is, energy can neither be created nor destroyed. Through countless experiments, we discover that the amount of energy at the beginning of any experiment is equal to the amount of energy at the end of the experiment. Similarly, extensive experiments have demonstrated that matter is conserved as well. However, we know that matter merely is a form of energy, as revealed by the famous Einstein equation of equivalence, E = mc2, where E is energy, m is mass, and c is the speed of light. Therefore, to be absolutely correct, one ought to speak of the conservation of mass-energy. But if we restrict ourselves to processes that do not involve conversion between matter and energy, then we can view the conservation of energy and the conservation of matter as different manifestations of the first law of thermodynamics.
The second law of thermodynamics is different. It states that, while energy is conserved, energy becomes less useful over time. What makes energy useful is the difference, or gradient, that exists between the energy at two different locations. We can exploit that energy gradient to operate engines to do work, much as biological systems use energy gradients to sustain life. The natural tendency is for energy gradients to decrease with time so that energy becomes less useful to do work. Physicists define entropy to measure the degree that energy is less useful. Thus, more entropy corresponds to less useful energy. According to the second law of thermodynamics, the entropy of the universe must increase with time.
The first and second laws of thermodynamics are well-established, and they appear universally to apply.
The first and second laws of thermodynamics are well-established, and they appear universally to apply. Of course, there is no problem with the two operating simultaneously today, but a startling conclusion results if we extrapolate them into the past. If the first law of thermodynamics has always been true, then the universe must have always existed. Otherwise, sometime in the past energy must have spontaneously appeared when none had previously existed. But this would violate the first law of thermodynamics. Hence, the first law of thermodynamics requires that the universe be eternal. But what if we extrapolate the second law of thermodynamics into the past? If the universe was eternal, there would have been more than ample time for the universe to have already reached its maximum state of entropy, with no useful energy remaining. The fact that today we can use heat engines and that biological systems operate today reveals that the universe is far from the maximum entropic state. Therefore, the universe cannot be eternal, and hence the universe must have had a beginning in the finite past.
But this produces a contradiction: the first law of thermodynamics demands that the universe be eternal, while the second law of thermodynamics demands that the universe cannot be eternal. Both laws appear to be fundamental and inviolate, so there is no way one law can be made subordinate to the other. One could hypothesize that in the past one of the two laws did not apply, but that would be a departure from the way in which the natural world is known to operate. The physical world today follows these two laws (and others), so any past departure from how the world now works would have amounted to a non-physical operation. Another word for non-physical is metaphysical. There is no physical mechanism whereby physical processes would suddenly change. In fact, such a change would undermine the underlying principle of physical processes (and makes science as we know it possible). Thus, if physical processes changed at some time, it must have had a cause outside of the physical. That is, the origin of the universe requires a radical departure from how the physical world operates Hence, the origin of the world is beyond the realm of science, as science is the study of the physical, or natural, world, not the metaphysical or the spiritual.
Ultimately, consideration of the first and second laws of thermodynamics in the past leads to the conclusion that the origin of the universe is a metaphysical or spiritual question, not a physical one
Many physicists (including astronomers and cosmologists) are aware of this problem. Therefore, those committed to naturalism have attempted to explain away this problem by appealing to quantum fluctuations. However, as I have discussed elsewhere, there are problems with this explanation. Ultimately, consideration of the first and second laws of thermodynamics in the past leads to the conclusion that the origin of the universe is a metaphysical or spiritual question, not a physical one. Therefore, using science, we can conclude that the origin of the universe is not a question that science is equipped to answer on its own. Since science can’t tell us where the universe came from, the only consistent way to study the origin of the universe is to realize that the Creator God exists and that he is not part of the physical universe. He is transcendent. The God who made all was not himself created. This is exactly what the Bible says: ”All things were made through him; and without him was not anything made that was made” (John 1:3). One ought to begin the study of the origin of the universe with God.