That is, energy can not be created or destroyed?
No.
The energy is still present. It just changes forms. and gets distributed over a larger area.
At the present time, it seems to me, scientists sort of dodge the problem Isn’t it the case that by making some reasonable assumptions most characteristics of the universe can be computed back to Planck Time? That is, the Big Bang model predicts the abundances of various elements, and as a valid inference the existence and character of the background microwave radiation.
But before Planck Time, nothing is known about how things acted and presently known physical principles can’t be used to figure it out.
Just to add to Beastal’s question, what about the entropy and enthalpy of the universe? Since heat cannot flow out of the universe, how can the enthalpy change? What about entropy? Was entropy at the moment of the big bank at an all-time low?
(Sorry if this is a hijack, Beastal, but since you were asking about the Big Bank and thermodynamics, I thought it would be appropriate)
I always thought “Big BANK” theory held that jamming too many pennies into a plastic pig would cause its mass to compress into a neutron star.
As for Big BANG, it does create certain problems when viewed with thermodynamics, but I always preferred to believe that the law of physics as we know them didn’t even exist until the universe had already started, i.e. for that first million billion trillion zillionth of a second, all bets were off.
Heat doesn’t have to “flow out of the universe” for energy to become unavailable.
Look at it this way. Anything that is at a temperature higher than absolute zero (-273.something or other) below 0[sup]o[/sup]C) contains energy. This energy can only do something when it moves from a higher to a lower temperature. When it does that, the low temperature is raised and the high temperature is lowered. Eventually they will be equal and energy will no longer flow. There is plenty of energy but none of it is available to do work.
And, as I said, the present physical principles can’t be applied before Planck Time. So you can’t legitimately talk about entropy at the instant (assuming that’s the word since time didn’t exist either) of the Big Bang.
http://www.talkorigins.org/faqs/thermo.html
Lots of answers here.
First of all I don’t think Big Bang violates any laws in Thermodynamics. What you are thinking is the Conservation of Matter and Energy. According to modern physics, physical laws are 4-dimensional constants that hold true within this universe. Before the Bang, these laws didn’t exist.
A better way to think of the first law is “The energy of the universe is constant.” And it is, from the Big Bang (the beginning of the universe) on.
The Universe is Just One of Those Things That Happens From Time To Time contains a theory which addresses the conservation problems. As my days of hard-core astrophysics are behind me, I’ll leave the rigorous contemplation of its merits to the younguns. However, it’s mighty appealing on its face…
nice… they brought up the theory of multiplicity (aka the “many worlds theory”)… great stuff 
read the book that stephen baxter had published, “the time ships”. its a good book…
I’ll go back to lurking now.
I believe you could also argue that the laws of physics were created by the Big Bang, so you couldn’t be violating a non-existent law beforehand, as it were.
That’s the answer I got 18 years ago when, as a physics undergrad, I asked the same question of our resident cosmologist.
Thermodynamics has nothing to do with it. The laws of Thermodynamics were promulgated before the advent of modern atomic theory. In fact, classical thermodynamics doesn’t even mention atoms, electrons, etc…you can’t correlate something that happened when the universe was extremely strange with 19th century mechanics.
So it’s like a First Cause that is outside the chain of causation? velly intelesting.