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Originally Posted by Og How does emergence not imply a cause or source? From what did it emerge? |
It implies a quality (or, if you wish, a capacity). One can argue, as does Hawking and others, that
"before the big bang" is a cognitively meaningless concept, while simultaneously noting that out of this
'initial condition' emerged all that we see around us.
At the same time, it might be wise not to over-state what we know. For example ...
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Bojowald works on loop quantum gravity (LQG) – a theory that seeks to unify the otherwise incompatible theories of general relativity and quantum mechanics. In LQG, space-time is made of tiny interconnected loops, each only 10 -35 metres across, that form a smooth fabric much like a shirt's fabric is smooth even though it is woven from separate threads.
Bojowald and his colleagues have run the equations of LQG backwards and shown that they can avoid the singularity. They showed that as the universe collapses, it reaches a point at which it bounces back in a big bang, and the process repeats. Cosmic 'forgetfulness'
Does that mean that one day we can, either mathematically or via observations, know about the pre-big bang universe? To answer this question, Bojowald developed a simple LQG model to determine the limits of what we can know. In his model, he assumed that the physical properties of the universe were the same everywhere and that the kind of matter it contained did not interact with itself. The model included gravity but not radiation.
The model showed that most, but not all, of the information about what came before the big bang gets irretrievably lost through the big bang transition. And in a perpetual cycle of big bangs and crunches, this information loss means no two universes are ever the same. Bojowald calls this "cosmic forgetfulness".
Cosmologist Paul Steinhardt of Princeton University says that Bojowald's model is right in principle. "It's important to lose some information, but not everything," he says. Thomas Thiemann of the Max Planck Institute for Gravitational Physics in Golm, Germany, says that although some of Bojowald's assumptions may turn out to be too simple, the model is "the cleanest derivation of a pre-big bang scenario that any physical theory has delivered so far". [source]
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Apparently discussions of a
"pre-big bang scenario" are alive and well.
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Originally Posted by Og I was not meaning to imply that we know the exact details of what's going on at a singularity, but what's clear is that time/causality do not behave normally (as they do on earth). |
I assumed that you were implying that
"Whatever time is and whatever space is, it has the properties expressed in the theory of general relativity as quoted here." I'm merely pointing out that your assertion is false for t less than one Planck time and that general relativity is an emergent quality.