Reference: http://www.hawking.org.uk/the-beginning-of-time.html

Predictions of No Boundary Condition proposal:

1) Irregularities in the current universe same as the Big Bang theory predicts and it is also varified by the CMB map.

2) Non-time reversal Big Crunch fate of the universe.

Questions: a) I'm curious to know if the No Boundary Condition proposal predicts more such things and if these predictions can be varified? b) Is there any prediction(s) of the No Boundary condition proposal that are different from the Big Bang evolutionary theory for the current state of the universe?


The Big Bang theory is very well established. The problem is that it just that there are questions left unanswered by the hot big bang scenario. What quantum cosmology adds is a description of the very first moments, at a time when some form of quantum mechanics was important. In this way we could assign probabilities to various alternative histories, like in quantum mechanics. For example; how likely is the value of the observed amount of e-folds of inflation? How likely is the approximate homogeneity we observe? These are the types of questions quantum cosmology may answer. In fact, it better agrees with the big bang scenario if it is to be taken seriously! Some predictions are listed here by Hartle; http://web.physics.ucsb.edu/~quniverse/nbwf-pred1.html. Let me however warn you; there are still a lot of problems with the NBWF, and predictions are often rather indications from toy-models. There is a lot of debate and a lot of reformulation of the proposal. Things like "non-time reverson big crunch fate', I would be more careful with.

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