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Name: Elvis D.
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Question:
Energy can neither be created nor can be destroyed but only can be transformed. This is one of the most important statement in physics, "The Law of the Conservation of Energy" If this is true, then when did the first energy come from? i.e. Was energy created at the origin of the universe?



Replies:
There are two issues here. Neither is easy, nor obvious:
The first is that "energy" is an abstraction. This is a difficult concept to get a grip on because energy is slipped into our thinking so "smoothly" and so soon in our physics education. It is made to appear so sacred, so "obvious" that who dares challenge the conservation laws! But look what happens in the practice of teaching "elementary" physics. We immediately invoke friction-free inclined planes, pulleys, etc. because if we do not then "energy" is not conserved because of friction and heat losses. Then enters thermodynamics: which deals with the conversions of mechanical work and heat, but look what has to be done -- idealized "reversible" infinitely slow processes must be invoked to "save" the laws of conservation.

Theoreticians, especially Emmy Noether, in the 1930's were truly concerned about the laws of conservation and another aspect of physical laws, namely their symmetry. She proved mathematically that a quantity is conserved, if and only if, some element of symmetry is preserved. Energy is "conserved" because the equations governing energy are symmetric with respect to "time". Momentum is "conserved" because the equations governing momentum are symmetric with respect to "space coordinates". Angular momentum is "conserved" because the equations governing angular momentum are symmetric with respect to "rotation".

We should not lose sight of the fact that the properties of some very obscure particles were predicted based upon other conservation laws holding true, without the particles ever having been observed experimentally. That is certainly a leap of "faith".

The second part of your question has to do with what happened "once upon a time" in the first microscopic fractions of a second after the creation of the Universe. And to the extent that I am able to fathom the problem, the honest answer is, "No one knows.".

Vince Calder


Elvis,

If the universe began with a "Big Bang", then the energy had to have already been here.

One theory is that it was all compressed into tightly packed matter. Energy can be in the form of matter, based on Einstein's E=mc^2. That tightly packed matter then exploded, much of the matter-energy converting into other forms.

Another theory is oscillation. The universe has always been here, and always will be. The universe expands to a certain limit, and then it collapses back to its compressed form. The universe does this repeatedly. It always has been oscillating and always will be oscillating.

Both of the above assume that the universe is all that exists. It is possible that other sources of energy do exist, other universes, other dimensions, a variety of possibilities. Because we would have no way to measure such a thing, science tends to limit itself to the first two options. We really have no way to know which is true.

Dr. Ken Mellendorf
Physics Instructor
Illinois Central College



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