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Robert J. Grave
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Isn't the big bang, the universe from nothing, a violation of the consevation of mass/energy since mass/energy can not be created or destroyed?
The Big Bang theory says that our universe once was in a very hot and dense state. What happened before that is open for speculation, since we do not know what physical laws hold under such extreme conditions. The quote "universe from nothing" mearly sounds like some creationism propaganda (i.e. something made up by people who have no clue what the Big Bang theory is about...)Robert J. Grave said:the big bang, the universe from nothing
The singularity is a consequence of GR, which we know is not a correct description of gravity under such extreme conditions. For that we need a quantum gravity theory, something we're still looking for. The singularity is hence just an artefact of applying a physical theory (GR) in a place (early universe) where it does not hold very good.Robert J. Grave said:The big bang therory, I understand, states that the universe began as a singularity at extreme tempatures and expanded from there.
wiki said:the Big Bang is the scientific theory that the universe emerged from a tremendously dense and hot state about 13.7 billion years ago.
EL said:The Big Bang theory says that our universe once was in a very hot and dense state. What happened before that is open for speculation, since we do not know what physical laws hold under such extreme conditions. The quote "universe from nothing" mearly sounds like some creationism propaganda (i.e. something made up by people who have no clue what the Big Bang theory is about...)
hellfire said:heusdens, Vilenkin does not use the term "nothing" to mean nothing at all (as done in philosophy), but to describe a state of vanishing classical space. Take a look to this post and the link there.
wxrocks said:My 2 cents -- Really -- the first 100 to 1000 seconds of existence are pure theory/speculation anyway. Anyone who is trying to explain the universe before that time is selling something! Because we don't have a good understanding of the physics at those extreme conditions, there is no way to say what the universe was doing before that point. Was it nothing, was it something, was it whatever -- all these questions can be asked, but to say for sure it was one way or another is pretty much a guess.
heusdens said:Inflation is past time eternal in the sense that 'once' it occurs, it can go on forever, which also leads to the conclusion, it didn't have to start at some time.
In general, the conservation equation that applies in cosmology follows from the divergenceless energy-momentum tensor of a perfect fluid that describes some of the components of the universe:heusdens said:But to go back to the topic (conservation of mass/energy) how does inflation treat these? I assume the conservation of mass/energy is still valid under inflation?
hellfire said:In general, the conservation equation that applies in cosmology follows from the divergenceless energy-momentum tensor of a perfect fluid that describes some of the components of the universe:
[tex]\partial_0 \rho + 3H(\rho + p) = 0[/tex]
During inflation the energy density of the scalar field that drives inflation remains constant, but [itex]p = - \rho[/tex] and the equation is satisfied.
The law of conservation of mass/energy states that mass and energy cannot be created or destroyed, only transformed from one form to another.
The first law of thermodynamics is a restatement of the law of conservation of energy, which is a part of the law of conservation of mass/energy. This means that in any energy transfer or transformation, the total amount of energy remains constant.
No, the law of conservation of mass/energy is a fundamental principle of physics and has been observed to hold true in every known physical process. It is a universal law that cannot be violated.
The law of conservation of mass/energy is important because it allows scientists to make predictions about the behavior of physical systems. It also helps to explain the fundamental principles of energy, such as the conservation of momentum and the conservation of angular momentum.
There are no known exceptions to the law of conservation of mass/energy in the observable universe. However, in the quantum world, there are some phenomena that may appear to violate this law, such as virtual particles that spontaneously appear and disappear. However, these particles still follow the law of conservation of mass/energy when taken into account with the entire system.