Register | Sign In


Understanding through Discussion


EvC Forum active members: 64 (9164 total)
2 online now:
Newest Member: ChatGPT
Post Volume: Total: 916,889 Year: 4,146/9,624 Month: 1,017/974 Week: 344/286 Day: 0/65 Hour: 0/1


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Before the Big Bang
ICANT
Member
Posts: 6769
From: SSC
Joined: 03-12-2007
Member Rating: 1.6


Message 271 of 311 (413838)
08-01-2007 3:02 PM
Reply to: Message 267 by molbiogirl
08-01-2007 1:26 PM


Re: more on singularities
In fact, having read the relevant sections of the paper you quoted, I find your quote mining reprehensible. Taken out of context, this quote...
I have emphasized what I consider the two most remarkable features that I have learnt in my research on space and time: first, that gravity curls up spacetime so that it has a beginning and an end. Second, that there is a deep connection between gravity and thermodynamics that arises because gravity itself determines the topology of the manifold on which it acts.
This happens to be Dr. Hawking's summation of the entire lecture.
If leaving off the opening sentence:
As the arrow of time is not going to reverse, and as I have gone over time, I better draw
my lecture to a close.
amounts to reprehensible quote mining I guess I am guilty as charged.
The last three paragraphs of the lecture in their entirety is:
As the arrow of time is not going to reverse, and as I have gone over time, I better draw
my lecture to a close. I have emphasized what I consider the two most remarkable features
that I have learnt in my research on space and time: first, that gravity curls up spacetime
so that it has a begining and an end. Second, that there is a deep connection between
gravity and thermodynamics that arises because gravity itself determines the topology of
the manifold on which it acts.
The positive curvature of spacetime produced singularities at which classical general
relativity broke down. Cosmic Censorship may shield us from black hole singularities but
we see the Big Bang in full frontal nakedness. Classical general relativity cannot predict
how the universe will begin. However quantum general relativity, together with the no
boundary proposal, predicts a universe like we observe and even seems to predict the
observed spectrum of fluctuations in the microwave background. However, although the quantum theory restores the predictability that the classical theory lost, it does not do so
completely. Because we can not see the whole of spacetime on account of black hole and cosmological event horizons, our observations are described by an ensemble of quantum
states rather than by a single state. This introduces an extra level of unpredictability but
it may also be why the universe appears classical. This would rescue Schrodinger's cat
from being half alive and half dead.
To have removed predictability from physics and then to have put it back again, but
in a reduced sense, is quite a success story. I rest my case.
I assure you, Dr. Hawking and Dr. Penrose
I have not quoted or alluded to anything Dr. Penrose said in any of his three lectures as I have not read them. The three lectures given by Dr. Hawking is all I referenced.
Since you've chosen this highly technical paper to illustrate your point, why don't you take this opportunity to walk us through the Penrose-Hawking theorem and then explain why you think it supports the idea that all of spacetime has a beginning and an end.
Dr. Hawking said spacetime had a beginning and an end:
quote:
I have learnt in my research on space and time: first, that gravity curls up spacetime so that it has a begining and an end.
I looked up information and you said:
If you are "debating in good faith", per buz, then I suggest you come up with material from some place other than PBS, tripod, space.com and science@nasa.gov. I mean, seriously. Tripod? Tripod??? And these others sites are for children. Children.
Message 256
I take your advice and go to Dr. Hawking's website and get information. Now you want me to explain what Dr. Hawking says.
What kind of a game are you playing.
I could care less about what Dr. Hawking believes. Dr. Hawking believing something does not make it a fact.
If you want to know what I believe about the universe read Message 262
Dr. Hawking's view and mine are a long way apart.

"John 5:39 (KJS) Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me."

This message is a reply to:
 Message 267 by molbiogirl, posted 08-01-2007 1:26 PM molbiogirl has replied

Replies to this message:
 Message 276 by molbiogirl, posted 08-01-2007 3:52 PM ICANT has replied

ICANT
Member
Posts: 6769
From: SSC
Joined: 03-12-2007
Member Rating: 1.6


Message 272 of 311 (413841)
08-01-2007 3:06 PM
Reply to: Message 270 by Chiroptera
08-01-2007 2:31 PM


Re: more on singularities
ABE
I'm not sure what "facts" we can know about the early universe, and how we can really be sure whether we really "know" them. But this is the usually problem of epitstemology.
But if my theory is correct you will know all the facts one day.
Edited by ICANT, : To put the proper quote in so Chiroptera could stop scratching head trying to figure out what I was talking about.

"John 5:39 (KJS) Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me."

This message is a reply to:
 Message 270 by Chiroptera, posted 08-01-2007 2:31 PM Chiroptera has replied

Replies to this message:
 Message 273 by Chiroptera, posted 08-01-2007 3:12 PM ICANT has replied
 Message 275 by molbiogirl, posted 08-01-2007 3:43 PM ICANT has not replied

Chiroptera
Inactive Member


Message 273 of 311 (413842)
08-01-2007 3:12 PM
Reply to: Message 272 by ICANT
08-01-2007 3:06 PM


Re: more on singularities
Um, okay. Thanks.
Edited by Chiroptera, : No changes made: ICANT's correction doesn't change my response.

I've done everything the Bible says, even the stuff that contradicts the other stuff! -- Ned Flanders

This message is a reply to:
 Message 272 by ICANT, posted 08-01-2007 3:06 PM ICANT has replied

Replies to this message:
 Message 278 by ICANT, posted 08-01-2007 4:25 PM Chiroptera has not replied

ICANT
Member
Posts: 6769
From: SSC
Joined: 03-12-2007
Member Rating: 1.6


Message 274 of 311 (413844)
08-01-2007 3:25 PM
Reply to: Message 266 by NosyNed
08-01-2007 1:08 PM


Re: Big Bang as Fact
ICANT writes:
In other words God could have spoke everything into existence and everything in the universe coming into being and moving about to get in their positions would look just like what we see by observation.
NoseyNed writes:
Yes, since we don't know enough about it to say that isn't so.
NoseyNed writes:
What makes it very, very likely that the universe started in a state near to a singularity is GR and a host of observations all of which support that idea very strongly.
Those same observations would support the idea that God could have created the universe as well.
We can be just as sure God was the cause as we can be that singularity was the cause.
But most on EvC says God can not be explained and who or what created Him.
I say singularity can not be explained and who or what created it.
Both are accepted by faith.

"John 5:39 (KJS) Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me."

This message is a reply to:
 Message 266 by NosyNed, posted 08-01-2007 1:08 PM NosyNed has replied

Replies to this message:
 Message 277 by NosyNed, posted 08-01-2007 4:05 PM ICANT has replied

molbiogirl
Member (Idle past 2670 days)
Posts: 1909
From: MO
Joined: 06-06-2007


Message 275 of 311 (413846)
08-01-2007 3:43 PM
Reply to: Message 272 by ICANT
08-01-2007 3:06 PM


Re: more on singularities
Why are you quoting me and replying to Chi?
Edited by molbiogirl, : No reason given.

This message is a reply to:
 Message 272 by ICANT, posted 08-01-2007 3:06 PM ICANT has not replied

molbiogirl
Member (Idle past 2670 days)
Posts: 1909
From: MO
Joined: 06-06-2007


Message 276 of 311 (413853)
08-01-2007 3:52 PM
Reply to: Message 271 by ICANT
08-01-2007 3:02 PM


Re: more on singularities
I have not quoted or alluded to anything Dr. Penrose said in any of his three lectures as I have not read them. The three lectures given by Dr. Hawking is all I referenced.
Really?
The first sentence of the paper:
In these lectures Roger Penrose and I will put forward our related but rather different viewpoints on the nature of space and time.
And you haven't answered my question. Where do Drs. Hawking and Penrose suggest that ALL of spacetime has a beginning and an end? ALL. A-L-L. Provide quote or link.
ABE
Hint The answer you're looking for has to do with geodesic incompleteness.
Edited by molbiogirl, : No reason given.

This message is a reply to:
 Message 271 by ICANT, posted 08-01-2007 3:02 PM ICANT has replied

Replies to this message:
 Message 281 by ICANT, posted 08-01-2007 5:47 PM molbiogirl has replied

NosyNed
Member
Posts: 9004
From: Canada
Joined: 04-04-2003


Message 277 of 311 (413858)
08-01-2007 4:05 PM
Reply to: Message 274 by ICANT
08-01-2007 3:25 PM


The Big Bang On Faith?
We can be just as sure God was the cause as we can be that singularity was the cause.
But most on EvC says God can not be explained and who or what created Him.
I say singularity can not be explained and who or what created it.
No one is saying that the singularity was the case. What we are saying, yet again, is that the theory that explains the big bang and it's behavior does NOT explain the point of origin of the big bang. The singularity means exactly that. It means that GR breaks down and gives no answers at that point. That is, it means that it does not explain the origin.
The big bang itself deals with after that. It is most definitely not taken on faith. As I mentioned before it is currently accepted because of the large number of observations and the agreement with the math. That is definitely NOT faith.
The current answer to where all that came from is : "We don't know."
You are happy to follow the historic course of putting God into the "we don't know". Others are not. We all await the outcome.
I asked you before what happens to your faith if we do start to "know". Do you wish to follow the followers of Vulcan at his forge under the volcano?
If your God (or some other) did start the universe at point of the GR singularity or started it with n-dimensional branes bumping around in an infinite n-spacetime all we do is learn how your God did it all. (well, "how"to a point only. The details of how to create an n-spacetime might elude us for a bit ).
Right now it appears pretty darn certain that some god (if any)definitely chose (for whatever reasons) to set the universe in motion at a point of extremely high density and let it expand from there. It seems we are all in agreement on that and we do not have to take that on faith. We see good solid evidence for it.
What has to be taken on faith right now is that either a god had something to do with it or that we will learn enough to explain it all without one being needed. Neither of us is in any position to be terribly sure of which answer is right or even that we will ever get to an answer.
All I think I have on my side is history: over and over the god of the gaps argument has been used. To date it has always proved to be a mistake. No Vulcan at his forge, no Jupiter with his thunder bolts, no Apollo and his chariot, no disease causing demons, no geological layers from a single flood etc.
That sure doesn't guarantee that the trend will extrapolate onward. But...

This message is a reply to:
 Message 274 by ICANT, posted 08-01-2007 3:25 PM ICANT has replied

Replies to this message:
 Message 279 by molbiogirl, posted 08-01-2007 4:54 PM NosyNed has not replied
 Message 280 by ICANT, posted 08-01-2007 5:08 PM NosyNed has not replied

ICANT
Member
Posts: 6769
From: SSC
Joined: 03-12-2007
Member Rating: 1.6


Message 278 of 311 (413862)
08-01-2007 4:25 PM
Reply to: Message 273 by Chiroptera
08-01-2007 3:12 PM


Re: more on singularities
Um,
I corrected Message 272 so you could stop scratching your head trying to figure out what I was talking about.

"John 5:39 (KJS) Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me."

This message is a reply to:
 Message 273 by Chiroptera, posted 08-01-2007 3:12 PM Chiroptera has not replied

molbiogirl
Member (Idle past 2670 days)
Posts: 1909
From: MO
Joined: 06-06-2007


Message 279 of 311 (413866)
08-01-2007 4:54 PM
Reply to: Message 277 by NosyNed
08-01-2007 4:05 PM


Re: The Big Bang On Faith?
No one is saying that the singularity was the case. What we are saying, yet again, is that the theory that explains the big bang and it's behavior does NOT explain the point of origin of the big bang. The singularity means exactly that. It means that GR breaks down and gives no answers at that point. That is, it means that it does not explain the origin.
Yes!
Oh thank you, Ned.
What we are saying, yet again, is that the theory that explains the big bang and it's behavior does NOT explain the point of origin of the big bang. The singularity means exactly that.
(emphasis added)
Yes yes yes.

This message is a reply to:
 Message 277 by NosyNed, posted 08-01-2007 4:05 PM NosyNed has not replied

ICANT
Member
Posts: 6769
From: SSC
Joined: 03-12-2007
Member Rating: 1.6


Message 280 of 311 (413871)
08-01-2007 5:08 PM
Reply to: Message 277 by NosyNed
08-01-2007 4:05 PM


Re: The Big Bang On Faith?
The big bang itself deals with after that. It is most definitely not taken on faith.
We were not talking about the big bang.
The big bang is the result of what happened at T=0.
If you can explain that moment please do, if not you take in on faith.
I asked you before what happens to your faith if we do start to "know".
I answered your question.Message 262
So if:
quote:
So I have no problem with any age that science could ever come up with for anything, I will just think it was a lot longer.
does not answer your question you will need to be more specific, than talking about mythology.
Right now it appears pretty darn certain that some god (if any)definitely chose (for whatever reasons) to set the universe in motion at a point of extremely high density and let it expand from there. It seems we are all in agreement on that and we do not have to take that on faith. We see good solid evidence for it.
I got no problem with that.
What has to be taken on faith right now is that either a god had something to do with it or that we will learn enough to explain it all without one being needed. Neither of us is in any position to be terribly sure of which answer is right or even that we will ever get to an answer.
I agree.
All I think I have on my side is history: over and over the god of the gaps argument has been used. To date it has always proved to be a mistake.
In Message 262to you I put forth my views about the universe.
I know the gap you are refering to between Gen. 1:1 and Gen. 1:2 but those 2 verses don't belong in the same time zone must less the same chapter. A gap would be a time in which nothing happened. That never happened.
Edited by ICANT, : No reason given.

"John 5:39 (KJS) Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me."

This message is a reply to:
 Message 277 by NosyNed, posted 08-01-2007 4:05 PM NosyNed has not replied

ICANT
Member
Posts: 6769
From: SSC
Joined: 03-12-2007
Member Rating: 1.6


Message 281 of 311 (413894)
08-01-2007 5:47 PM
Reply to: Message 276 by molbiogirl
08-01-2007 3:52 PM


Re: more on singularities
Really?
The first sentence of the paper:
In these lectures Roger Penrose and I will put forward our related but rather different viewpoints on the nature of space and time.
Talk about quote mining.
Do you ever read anything?
Here is the first paragraph:
1. Classical Theory
S. W. Hawking
In these lectures Roger Penrose and I will put forward our related but rather different viewpoints on the nature of space and time. We shall speak alternately and shall give three lectures each, followed by a discussion on our different approaches. I should emphasize that
these will be technical lectures. We shall assume a basic knowledge of general relativity and quantum theory.
We shall speak alternately.
And shall give three lectures each.
Followed by a discussion on our different approaches.
I referenced only the three lectures by Dr. Hawking.
Where do Drs. Hawking and Penrose suggest that ALL of spacetime has a beginning and an end?
Dr. Penrose has nothing to do with the summation given by Dr. Hawking in his lecture.
Dr. Hawking said in summation of his lecture:
3. Quantum Cosmology
S. W. Hawking
Page 60
Hawking writes:
As the arrow of time is not going to reverse, and as I have gone over time, I better draw
my lecture to a close. I have emphasized what I consider the two most remarkable features
that I have learnt in my research on space and time: first, that gravity curls up spacetime
so that it has a begining and an end. Second, that there is a deep connection between
gravity and thermodynamics that arises because gravity itself determines the topology of
the manifold on which it acts.
Its time to stop these childish games you want to play.

"John 5:39 (KJS) Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me."

This message is a reply to:
 Message 276 by molbiogirl, posted 08-01-2007 3:52 PM molbiogirl has replied

Replies to this message:
 Message 282 by molbiogirl, posted 08-01-2007 6:31 PM ICANT has replied

molbiogirl
Member (Idle past 2670 days)
Posts: 1909
From: MO
Joined: 06-06-2007


Message 282 of 311 (413908)
08-01-2007 6:31 PM
Reply to: Message 281 by ICANT
08-01-2007 5:47 PM


Re: more on singularities
The theory you are quote-mining is called the Penrose-Hawking theory.
And you can repeat that quote about gravity curling up all you want, buster. It doesn't mean spacetime has a beginning and an end. You have taken Drs. Hawking and Penrose's words out of context.
I referenced only the three lectures by Dr. Hawking.
Bull! You referenced one sentence on page 10 and one paragraph on page 60.
It's a 61 page document! You are saying it can be summed up by that one sentence and/or that one paragraph!
I seriously doubt you read anything else in those papers. But I shouldn't assume that, now should I?
Let's see.
What do you make of this bit from page 6, dear boy?
The physical significance of global hyperbolicity comes from the fact that it implies that there is a family of Cauchy surfaces f(t) for U. A Cauchy surface for U is a space like or null surface that intersects every time like curve in U once and once only. One can predict what will happen in U from data on the Cauchy surface, and one can formulate a well behaved quantum field theory on a globally hyperbolic background. Whether one can formulate a sensible quantum field theory on a non globally hyperbolic background is less clear. So global hyperbolicity may be a physical necessity. But my view point is that on shouldn't assume it because that may be ruling out something that gravity is trying to tell us. Rather one should deduce that certain regions of spacetime are globally hyperbolic from other physically reasonable assumptions.
Earlier I gave you a hint. The reason your idea that spacetime has a beginning and an end is wrong has to do with geodesic incompleteness.
I'm not gonna do the work. You read the paper. You find your mistake.

This message is a reply to:
 Message 281 by ICANT, posted 08-01-2007 5:47 PM ICANT has replied

Replies to this message:
 Message 283 by cavediver, posted 08-01-2007 7:43 PM molbiogirl has not replied
 Message 284 by ICANT, posted 08-01-2007 9:55 PM molbiogirl has replied

cavediver
Member (Idle past 3671 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 283 of 311 (413913)
08-01-2007 7:43 PM
Reply to: Message 282 by molbiogirl
08-01-2007 6:31 PM


Re: more on singularities
It's a 61 page document!
Of course, some of us were at the actual lectures

This message is a reply to:
 Message 282 by molbiogirl, posted 08-01-2007 6:31 PM molbiogirl has not replied

ICANT
Member
Posts: 6769
From: SSC
Joined: 03-12-2007
Member Rating: 1.6


Message 284 of 311 (413930)
08-01-2007 9:55 PM
Reply to: Message 282 by molbiogirl
08-01-2007 6:31 PM


Re: more on singularities
Bull! You referenced one sentence on page 10 and one paragraph on page 60.
How much came from Dr. Penrose's lectures?
It's a 61 page document! You are saying it can be summed up by that one sentence and/or that one paragraph!
I did not sum up Dr. Dawking's lecture he did.
I'm not gonna do the work. You read the paper. You find your mistake.
I did not ask you to do the work.
I did read the 61 pages They are the three lectures Dr. Dawking delivered.
Dr. Dawking summed up the lectures on page 60 I can't help it if you get bent out of shape because of what he said.
Understand one thing I did not write the paragraph on page 60 which says:
Hawking writes:
As the arrow of time is not going to reverse, and as I have gone over time, I better draw
my lecture to a close. I have emphasized what I consider the two most remarkable features
that I have learnt in my research on space and time: first, that gravity curls up spacetime
so that it has a begining and an end.
Second, that there is a deep connection between
gravity and thermodynamics that arises because gravity itself determines the topology of
the manifold on which it acts.
This is word for word what Dr. Hawking said. I have added nothing but bolding and underlining of part of the statement.
If you have an argument with what Dr. Dawking said I suggest you take it up with him.

"John 5:39 (KJS) Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me."

This message is a reply to:
 Message 282 by molbiogirl, posted 08-01-2007 6:31 PM molbiogirl has replied

Replies to this message:
 Message 285 by molbiogirl, posted 08-02-2007 6:08 PM ICANT has replied

molbiogirl
Member (Idle past 2670 days)
Posts: 1909
From: MO
Joined: 06-06-2007


Message 285 of 311 (414100)
08-02-2007 6:08 PM
Reply to: Message 284 by ICANT
08-01-2007 9:55 PM


Re: more on singularities
cavediver:
Of course, some of us were at the actual lectures.
Awwww. Cave. You lucky critter you. As you know, I [heart] physics, but I doubt I could have followed that lecture anyway. That s*** is d-e-e-p. However, I can decode enough of it to know that little mister ICANT hasn't got his ducks in a row.
ICANT. Listen carefully. Duck No. 1.
The big bang is the result of what happened at T=0.
Dr. Hawking:
Classical general relativity cannot predict how the universe will begin.
It's a quote from your favorite paragraph!
Duck No. 2.
Wiki:
The singularity theorems use the notion of geodesic incompleteness as a stand-in for the presence of infinite curvatures. Geodesic incompleteness is the notion that there are geodesics, paths of observers through spacetime, that can only be extended for a finite time as measured by an observer traveling along one. Presumably, at the end of the geodesic the observer has fallen into a singularity or encountered some other pathology at which the laws of general relativity break down.
Wiki again:
In general relativity, there are several versions of the Penrose-Hawking singularity theorem. Most versions state, roughly, that if there is a trapped null surface and the energy density is nonnegative, then there exist geodesics of finite length which can't be extended.
Now do you get it?

This message is a reply to:
 Message 284 by ICANT, posted 08-01-2007 9:55 PM ICANT has replied

Replies to this message:
 Message 286 by cavediver, posted 08-02-2007 6:46 PM molbiogirl has not replied
 Message 287 by ICANT, posted 08-02-2007 8:41 PM molbiogirl has not replied

Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024