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Big Bang
#31
RE: Big Bang
But if you don't believe in 'The Big Bang', you can't be a true atheist, cause everyone knows that atheists have absolute faith in science.















Whoops, better not forget this. :-)




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#32
RE: Big Bang
(October 18, 2018 at 7:46 am)Little lunch Wrote: But if you don't believe in 'The Big Bang', you can't be a true atheist, cause everyone knows that atheists have absolute faith in science.















Whoops, better not forget this.  :-)

As it turns out there is no absolute certainty and science is the best thing we have, as Matt Dillahunty said.
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#33
RE: Big Bang
That the Earth is curved is an absolute fact. Ditto for the expansion of the Universe.
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#34
RE: Big Bang
(October 18, 2018 at 10:19 am)Jehanne Wrote: That the Earth is curved is an absolute fact.  Ditto for the expansion of the Universe.

How much curvature does the expansion of the Universe show?
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#35
RE: Big Bang
(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):

[Image: 1BqlmI4.jpg]

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.
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#36
RE: Big Bang
Hi Polymath,

We've been through this before:

http://www.preposterousuniverse.com/blog...-equation/

QFT did not "replace" QM.
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#37
RE: Big Bang
(October 18, 2018 at 1:59 pm)Jehanne Wrote: Hi Polymath,

We've been through this before:

http://www.preposterousuniverse.com/blog...-equation/

QFT did not "replace" QM.

But, as your link shows, the Schrodinger equation needed to go beyond the single particle non-relativistic equation is different than the one in Griffiths. In fact, the appropriate equation is usually derived from the Lagrangian formulation and can be put into the Schrodinger form, but the standard Schrodinger equation is the non-relativistic version of things (although it can be multi-particle---which the one in Griffiths is not).
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#38
RE: Big Bang
(October 18, 2018 at 10:19 am)Jehanne Wrote: That the Earth is curved is an absolute fact.  Ditto for the expansion of the Universe.

Quantify “absolute”.
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#39
RE: Big Bang
(October 18, 2018 at 5:05 pm)Anomalocaris Wrote:
(October 18, 2018 at 10:19 am)Jehanne Wrote: That the Earth is curved is an absolute fact.  Ditto for the expansion of the Universe.

Quantify “absolute”.

Is that a quibble or a pounce?
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#40
RE: Big Bang
(October 18, 2018 at 5:43 pm)Gawdzilla Sama Wrote:
(October 18, 2018 at 5:05 pm)Anomalocaris Wrote: Quantify “absolute”.

Is that a quibble or a pounce?

It’s a pounce.

Any quantification equivalent to assessed probability of 1.0000000000000000....00000 or 0.000000000000000...0000 is menifestly unsupportable even for seeming certain facts as earth being curved. Any qualification of absolute as being somewhere in between these two values implies “absolute” is qualitatively indifferent from “relative”.
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