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The first law of thermodynamics states that energy cannot be created. If that's the case, how did the universe come into existence? I mean, doesn't that require energy to be created?

Excuse my ignorance if this question seems a bit idiotic. I haven't read much in thermodynamics, hence my lack of understanding.

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marked as duplicate by Qmechanic Feb 15 '18 at 20:36

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    $\begingroup$ One has to realize that the universe is currently modeled with General Relativity. In General relativity conservation of energy is not guaranteed, as you can see in this article math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html $\endgroup$ – anna v Feb 15 '18 at 17:02
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    $\begingroup$ Are you sure you are not putting the cart before the horse here? The universe is defined not only by the the "stuff" that's in it, (especially energy), but also by the laws of nature that describe it. So while I can't say what event (if any) caused the universe to appear, I think it might be safe to say, despite the possible evolution of the laws and physical " constants" over time, that the laws came into existence at the same time as the universe did. $\endgroup$ – user184990 Feb 15 '18 at 19:20
  • $\begingroup$ There are many questions that no respectable scientist claims to have answers to (yet). Among them are some of the "big" questions that religion has historically tried to answer. Questions such as "how did the universe come into existence?", "why is there something rather than nothing?", and so on. Physics simply doesn't have all the answers. There are even "easier" questions that we can't claim to answer (yet), like "what happens at the singularity inside a black hole?" Individual physicists may present hypotheses — but if they claim to have correct answers, beware. $\endgroup$ – Mike Feb 15 '18 at 19:53
  • $\begingroup$ What existed before anything existed? is not a question but a koan. Why can't people accept that energy is somehow built into the initial condition? $\endgroup$ – Bert Barrois Feb 15 '18 at 22:45
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It is not obvious that the universe did not exist before some moment in time.

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  • $\begingroup$ Are you saying that perhaps the universe always existed? $\endgroup$ – Dewton Feb 15 '18 at 15:27
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    $\begingroup$ @Dewton : I am saying that this is possible. $\endgroup$ – akhmeteli Feb 15 '18 at 15:29
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Stephen Hawking tried to answer that question in his book "A Brief History of Time". His answer is based on the uncertainty principle:

$$\Delta E\Delta t\geq \frac{\hbar}{2}$$

If you take that the total variance of energy of the universe to be $\Delta E=0$, then, according to this principle, you can have $\Delta t\rightarrow\infty$ and then, the universe can exist for an indefinite amount of time. The stated fact is that the total amount of energy of the universe is exactly $0$. The reason is that matter has "positive" energy from it's mass ($E=mc^2$) which is exactly balanced by "negative" binding energy (electrons in an atom, atoms in molecules, planet orbiting stars, stars clusters, galaxies, galaxies clusters, superclusters, etc.). Thus, the universe would have a total amount of energy equals to $0$.

To answer your question about the "creation of energy": it is sufficient to say that in the quantum mechanics realm, it is perfectly allowed to "borrow" energy from nothing. As long as the time when the energy is borrowed does not violate the uncertainty principle. This is a real effect that leads to spontaneous creation of particle-antiparticle pairs which have (or may have) a measurable effect (lamb shift, Hawking radiation, casimir effect, spontaneous emissions, etc.). These particles are also called "virtual particles" as they do not exist freely and cannot be measured directly. Thus, according to Hawking, the Universe could have spawned from such a quantum fluctuation as long as the total energy borrowed is $0$.

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