geordief

The Big Bang Theory, Expansion/Inflation plus "Explosion"

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geordief    47

I keep hearing that the "Big Bang" happened everywhere  and was not an explosion but an inflation or expansion.

 

Well ,it is not claimed that  the Big Bang Theory accounts for the 10^43 second prior to its  applicability . 

 

If the "Big Bang" happened "everywhere" does this not imply that at 10^43 seconds  "everything" was in the same place? Does this not also imply that the "volume" of everything at that time  had zero extent? (no top or bottom or left or right)

 

If there was "extent" then would not some areas of the observable Universe  differ from  other areas in that they originated from different areas of the Big Bang ? 

 

Or was the "extent" small enough to make these differences zero?

 

Second question about the "non explosion"...Is this explained by the fact that explosions need an external containment  of some kind  and this is not part of the BB Theory?

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Strange    2429
2 minutes ago, geordief said:

If the "Big Bang" happened "everywhere" does this not imply that at 10^43 seconds  "everything" was in the same place? Does this not also imply that the "volume" of everything at that time  had zero extent? (no top or bottom or left or right)

If you extrapolate back to time 0 (without taking quantum effects into account - because we don't really know how to do that) then everything is "at the same place" (i.e. with zero volume). That is not thought to be realistic.

At the earliest time we can plausibly extrapolate back to (the 10-43 seconds, you mention - although missed the minus sign!) the observable universe would have been very small but not zero sized. 

4 minutes ago, geordief said:

If there was "extent" then would not some areas of the observable Universe  differ from  other areas in that they originated from different areas of the Big Bang ?

This is a very, very good question. And one of the unanswered questions. For the universe to be as homogenous as it appears to be, it would be necessary for it to be in thermal equilibrium, meaning light could travel from one side to the other. If the universe was too large the would not be possible. This is the reason that an inflationary phase was suggested: the universe could have been small enough to be in equilibrium and then expanded very rapidly to match the early size we see. (That may all be a bit vague, but it is not a topic I know a lot about.) 

Quote

Second question about the "non explosion"...Is this explained by the fact that explosions need an external containment  of some kind  and this is not part of the BB Theory?

I think there are two reasons why the explosion idea doesn't work. The distribution of velocities of the matter in space would not match what we see even if we were at the centre of the explosion. Secondly, the theoretical idea of space expanding (and various predictions based on that) came first and then the evidence was found that was consistent with that.

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Area54    103

Further on the non-explosion, as far as I understand it the graphic choice of the word explosion was associated with the equally graphic phrase Big Bang as a means of communicating the idea in laymans terms. Hence, "explosion" never had any place within the theory itself and there need be no more reason for rejecting calling it an explosion than for not calling it a parrot.

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beecee    77
8 hours ago, geordief said:

I keep hearing that the "Big Bang" happened everywhere  and was not an explosion but an inflation or expansion.

 

Well ,it is not claimed that  the Big Bang Theory accounts for the 10^43 second prior to its  applicability . 

 

If the "Big Bang" happened "everywhere" does this not imply that at 10^43 seconds  "everything" was in the same place? Does this not also imply that the "volume" of everything at that time  had zero extent? (no top or bottom or left or right)

 

If there was "extent" then would not some areas of the observable Universe  differ from  other areas in that they originated from different areas of the Big Bang ? 

 

Or was the "extent" small enough to make these differences zero?

 

Second question about the "non explosion"...Is this explained by the fact that explosions need an external containment  of some kind  and this is not part of the BB Theory?

It's worth noting that the BB terminology being applied to the expanding universe/spacetime model, was a term of derision by Freddy Hoyle, an otherwise great physicist/astronomer, who just happened to be pushing the Steady State model. 

I have also heard and read that his apparent hatred for the BB was due to the fact that it obviously implied a beginning and subsequently an opening on which IDers and religious folk can hang their hat. It is to the credit of science and the scientific methodology though, that in spite of this, science went the way of empirical observations and evidence and did not shirk away.

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Strange    2429
7 minutes ago, beecee said:

It's worth noting that the BB terminology being applied to the expanding universe/spacetime model, was a term of derision by Freddy Hoyle

He always denied it was derisive. He just wanted a snappy alternative to "steady state" for the radio program he was doing. I am not old enough to remember that program, but I am old enough to remember science programs where the steady state and Big Bang models were debated on an equal footing because there was no overwhelming evidence for either!

Edited by Strange

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Area54    103
8 minutes ago, beecee said:

It's worth noting that the BB terminology being applied to the expanding universe/spacetime model, was a term of derision by Freddy Hoyle, an otherwise great physicist/astronomer, who just happened to be pushing the Steady State model.

This is not the case, although it is a common misbelief. Hoyle denied he intended it in a negative fashion. See here.

Edit: Cross posted with Strange.

Edited by Area54

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Strange    2429

p.s. Hoyle and Lemaitre were really good friends. They must have had some interesting debates after a few beers!

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Area54    103
Just now, Strange said:

p.s. Hoyle and Lemaitre were really good friends. They must have had some interesting debates after a few beers!

I understand that Lemaitre would become very expansive, but Hoyle was always very steady in his behvaiour.

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beecee    77
1 minute ago, Strange said:

He always denied it was derisive. He just wanted a snappy alternative to "steady state" for the radio program he was doing. I am not old enough to remember that program, but I am old enough to remember science programs where the steady state and Big Bang models were debated on an equal footing because there was no overwhelming evidence for either!

As a hairy arse school boy in the mid fifities, (ahh memories!) I vividly remember there were three models competing, (if that is the right word) the BB, Steady State, and Oscillating theory.

It was the Penzias/Wilson serendipitious discovery that gave the BB the impetus. What year was this radio program?

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beecee    77
7 minutes ago, Strange said:

He always denied it was derisive. He just wanted a snappy alternative to "steady state" for the radio program he was doing. 

 

6 minutes ago, Area54 said:

This is not the case, although it is a common misbelief. Hoyle denied he intended it in a negative fashion. See here.

Edit: Cross posted with Strange.

Ahhh, OK, thanks. 

2 minutes ago, Area54 said:

It's in the link I gave. 28th March 1949.

Yeah, OK, I'm a bit slow here. :) 

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Carrock    27
17 hours ago, beecee said:

I have also heard and read that his apparent hatred for the BB was due to the fact that it obviously implied a beginning and subsequently an opening on which IDers and religious folk can hang their hat. It is to the credit of science and the scientific methodology though, that in spite of this, science went the way of empirical observations and evidence and did not shirk away.

Bondi and Gold, who had collaborated with Hoyle, independently published a version of Steady State, which claimed there was no beginning, before Hoyle was ready to publish. Their theory was soon disproved with pencil and paper and no need for empirical observation.

In the speculative Mach's Principle and the Creation of Matter Hoyle clearly separates his theory from theirs, which he sarcastically describes as based on 'the "perfect" cosmological principle,' and goes on to discuss the past boundary conditions necessary to initiate the steady state universe.

He may well have been annoyed that Bondi and Gold picked his brains, gave IDers and religious folk a cheap victory and tarnished his own theory, which required empirical observation to disprove it.

Edited by Carrock
more clarity

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Airbrush    157
On ‎9‎/‎9‎/‎2017 at 5:49 AM, geordief said:

I keep hearing that the "Big Bang" happened everywhere....

.....

If the "Big Bang" happened "everywhere" does this not imply that at 10^43 seconds  "everything" was in the same place? Does this not also imply that the "volume" of everything at that time  had zero extent? (no top or bottom or left or right)

........

How can we assume "everywhere or anything" is contained within one big bang?  In a multiverse model there are an infinite number of big bangs, and our big bang would not be "everything".

Edited by Airbrush

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Strange    2429
24 minutes ago, Airbrush said:

How can we assume "everywhere or anything" is contained within one big bang?  In a multiverse model there are an infinite number of big bangs, and our big bang would not be "everything".

That is a possible scenario but there is no evidence for it. 

All we can realistically talk about is our universe. 

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Airbrush    157

Yes, and we cannot extrapolate that our big bang must be everywhere and everything.

Edited by Airbrush

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Strange    2429
15 minutes ago, Airbrush said:

Yes, and we cannot extrapolate that our big bang must be everywhere and everything.

It is everything we have evidence of. Anything beyond that is not science but guesswork.

(I don't think you know what the word "assumption" means.)

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Airbrush    157

Ok, assumption is the wrong word.

The OP states: "I keep hearing that the "Big Bang" happened everywhere"

It happened "everywhere" only if there is ONLY one big bang.

 

Edited by Airbrush

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Strange    2429
18 minutes ago, Airbrush said:

The OP states: "I keep hearing that the "Big Bang" happened everywhere"

Make that "our" Big Bang if it makes you happier.

19 minutes ago, Airbrush said:

It happened "everywhere" only if there is ONLY one big bang.

Our Big Bang happened everywhere in our universe. OK?

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geordief    47

Sure,by "everywhere" I just meant everywhere in our Universe at that time of development.

If multiverses ever become a testable theory then I might have to rephrase the question.....

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beecee    77
2 hours ago, Airbrush said:

How can we assume "everywhere or anything" is contained within one big bang?  In a multiverse model there are an infinite number of big bangs, and our big bang would not be "everything".

Even if there we multiple BBs from the quantum foam, each BB would form its own separate universe. All we can assume logically is that our BB created the universe we know and it is all there is and contains all we know....the rest is sheer speculation: Not that there's anything wrong with that. 

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Airbrush    157
On ‎9‎/‎10‎/‎2017 at 0:37 PM, Strange said:

Make that "our" Big Bang if it makes you happier.

Our Big Bang happened everywhere in our universe. OK?

Thank you.

On ‎9‎/‎10‎/‎2017 at 1:48 PM, beecee said:

All we can assume logically is that our BB created the universe we know and it is all there is and contains all we know....the rest is sheer speculation: Not that there's anything wrong with that. 

It is "all there is" locally.  We don't know about "all there is".  Be careful to not equate "all there is" with "all we know".  All we know is limited to the edge of the observable universe.

 

 

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Strange    2429
10 minutes ago, Airbrush said:

All we know is limited to the edge of the observable universe.

Hey, that's my line! :)

Edited by Strange

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beecee    77
3 hours ago, Airbrush said:

It is "all there is" locally.  We don't know about "all there is".  Be careful to not equate "all there is" with "all we know".  All we know is limited to the edge of the observable universe.

While it's true we don't know about "all there is," I believe that our assumptions about the isotropic and homogeneous nature of the observable universe, can be logically extrapolated to the universe as a whole that evolved from the BB. At the same time, any speculative idea re the possible many quantum fluctuations that may have arose from the quantum foam, would also probably be entirely different from the conditions imposed by our own local BB: Some fluctuations may have started to evolve and then like a soap bubble, due to initial conditions, may have burst: Others may have evolved and expanded at incredible rates to finally have reached maximum entropy...all most likely would have different initial conditions, that would see each entirely different from our own local BB, and consequently would all be unknown propositions.eg; the strength of gravity, the EMFs, etc etc 

Some day in the future, some bright spark may invent, discover or mathematically work out a logical explanation, consistent with the laws of physics, as to what if anything can or does exist outside our BB bubble universe: But hey! it's fun speculating within the bounds of science and the scientific methodology! We never know where it may lead.

Edited by beecee
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