RE: Big Bang
October 18, 2018 at 12:11 pm
(This post was last modified: October 18, 2018 at 12:19 pm by polymath257.)
(October 14, 2018 at 7:53 am)Jehanne Wrote:(October 13, 2018 at 3:36 am)purplepurpose Wrote: 13.8 Billions of years ago our universe started with the Big Bang. Question: energy and matter that created Big Bang was always there/eternal or it just Magically popped in to existence?
The Universe is likely infinite and eternal, that is, without a beginning, an end, or, an edge. The following theorem can be found in Professor David Griffith's book, Quantum Mechanics (both his 1st, 2nd, and, I presume, now 3rd edition):
Well, the problem is that the Schrodinger equation is not a relativistic equation. To get a version that is compatible with special relativity, you need to go to one of the quantum field theories (QFTs) such as QED or QCD.
More important is that we have no verified quantum theory of gravity, and that may be quite relevant to the issue of 'eternity'.
The classical theory of gravity is General Relativity. In that theory, time itself simply cannot be extended to 'before the Big Bang'. There is literally no before. Time, along with everything else, begins at the BB. In that case, the derivation in Griffiths simply fails because it models time as being infinite (and, I might add, flat).
That conclusion may or may not be modified when quantum effects are added in, but, again, we have no verified theory that unifies quantum mechanics and general relativity. It may well be that the 'singularity' (which is a term that seems to be widely misunderstood) is 'smoothed over' and that time can be extended back past the BB. But, again, it may not be possible. It depends on which of several candidate theories are correct.
In any case, the 'theorem' you posted has limitations that probably make it irrelevant to the current discussion.
(October 13, 2018 at 3:36 am)purplepurpose Wrote: 13.8 Billions of years ago our universe started with the Big Bang. Question: energy and matter that created Big Bang was always there/eternal or it just Magically popped in to existence?
Well, the imagery of 'popped' is almost certainly not what happened. Under our current understanding, whenever there was space and time, there was also matter and energy. But, it is possible that time only goes finitely far into the past. There may simply be no such thing as 'before the BB'.
The point is that spacetime is a unified geometry and that geometry is curved. That curvature is caused by energy density as well as other things, but the curvature may prevent some coordinates (like time) from being extended past a certain point.
A good analogy is the surface of a globe. Latitude and longitude are coordinates we use to describe our location on the globe. If we make an analogy where latitude corresponds to time (going north corresponds to forward in time) and longitude to space (a one-dimensional space), then the south pole is a 'singularity' where there is no 'before'. In the same way, the north pole is another 'singularity' where there is no 'after'.
In this analogy, mass and energy would exist everywhere on the globe and be conserved as we move north. Both exist 'through all time'. it's just that time itself is of finite duration.