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Natural Environment How Human History has been impacted by the environment, science, nature, geography, weather, and natural phenomena


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Old November 28th, 2012, 12:06 PM   #251

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Quote:
Originally Posted by sylla1 View Post
Hawking on a finite universe.
Having no boundary (as a sphere) is not the same as having no limits (as the same sphere).

Hawking's model is finite; it proposed limits.

That said, the critical point here is that Dr Hawking was talking here about one or several finite "universes" like our observable one Observable universe - Wikipedia, the free encyclopedia .

By definition, all those "universes" would be contained within the whole Universe as regularly defined, i.e. (Merriam-Webster)

Or like the equivalent definition of Wikipedia from a composite of at least four major encyclopedias & dictionaries Universe - Wikipedia, the free encyclopedia


AFAIK (I may be wrong, and I would love to be corrected here ) Hawking's model states nothing about the finiteness (or lack of it) of any such whole Universe as regularly defined above, i.e. the OP.




Just for the sake of clarity, IMHO there is currently simply no major scholar disagreement on the finite nature of the observable universe, as described by the Big Bang theory and supported by a plethora of empirical data.

If the OP is about the Universe as a whole, the whole existence under this later regular definition, my position must still remain the same; it is currently impossible to know if the Universe is infinite or finite.

This is the OP:
After 250 posts? As simple as possible;

The observable universe is clearly finite.

The whole Universe, who knows ?



(Yup, people and even scholars are using the same word for different concepts)
Let's evaluate the intrinsic value of such a discussion ... if conclusions were certain we will read about a certainly finite or infinite universe on school books ... [with or without limits].

A part this, I said too that Hawking consider the universe finite [like Einstein], but without limits.

A scientist is a free thinker ...

Quote:
“So long as the universe had a beginning, we could suppose it had a creator. But if the universe is really completely self-contained, having no boundary or edge, it would have neither beginning nor end: it would simply be. What place, then, for a creator?”
Stephen Hawking
Quote:
“Time and space are finite in extent, but they don't have any boundary or edge. They would be like the surface of the earth, but with two more dimensions.”
Stephen Hawking, Black Holes and Baby Universes
Free minds for free confrontations of opinions and ideas [also changing them].
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Old November 28th, 2012, 12:43 PM   #252
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Quote:
Originally Posted by AlpinLuke View Post
Let's evaluate the intrinsic value of such a discussion ... if conclusions were certain we will read about a certainly finite or infinite universe on school books ... [with or without limits].

A part this, I said too that Hawking consider the universe finite [like Einstein], but without limits.

A scientist is a free thinker ...





Free minds for free confrontations of opinions and ideas [also changing them].
Nope; a finite observable universe without boundaries, but naturally still with limits (hence finite); exactly as the sphere analogy.

Such conception of finiteness is not dependent of quantum mechanics, but of astronomical observations (naturally "newtonian") and especially of the Big Bang theory.
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Old November 28th, 2012, 01:24 PM   #253

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Originally Posted by sylla1 View Post
Nope; a finite observable universe without boundaries, but naturally still with limits (hence finite); exactly as the sphere analogy.

Such conception of finiteness is not dependent of quantum mechanics, but of astronomical observations (naturally "newtonian") and especially of the Big Bang theory.
First of all this part of the OP at this point has entered the legend !
Quote:
Simple answers would be appreciated
Now, I see that probably there is something to explain about the conceptualization of something "finite without limits".

Unfortunately we would have to leave again the field of cosmology to dive into philosophy. Anyway I can make a try [still in the field of physics].

To look well, we live on the surface of a sphere [actually Earth is not a perfect sphere, anyway is a good "sample"], so that we should be able to prove [or disprove] the conceptualization of the surface of a sphere being finite but without limits [even if reasoning about a 3D object, a sphere is a 3D object ...].

Let's try this:

if I invite a friend of mine to meet me "on the limit of the surface of Earth" [or on a limit / an edge of the surface of Earth, if we prefer] ... where would you expect me to wait for him?

[I mean in which physical point/s of the terrestrial surface].

More simple [in honor of the OP]

Where does the surface of Earth begin?
Where does the surface of Earth end?

Last edited by AlpinLuke; November 28th, 2012 at 01:31 PM.
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Old November 29th, 2012, 09:25 AM   #254

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Where does the surface of Earth begin?
Where does the surface of Earth end?
Begin: 4.54 billion years ago

End: 4 to 5 billion years from now
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Old November 29th, 2012, 09:41 AM   #255
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Some elementary English:
Quote:
fi·nite adjective
having definite or definable limits
(Merriam-Webster)

AFAIK the concept is equally valid in Italian or any other language I'm aware of.

Just check out any sphere.
(Because no infinite sphere is known)

Click the image to open in full size.

This (or any other) sphere naturally has no boundaries, but equally naturally it has limits: in geometrical terms, its surface.
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Old November 29th, 2012, 11:31 AM   #256

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Quote:
Originally Posted by Rasta View Post
Begin: 4.54 billion years ago

End: 4 to 5 billion years from now
Well, not when [temporally], but where [geometrically]. Temporally, you're absolutely right ...
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Old November 29th, 2012, 11:35 AM   #257

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You haven't understood the point.

Quote:
Originally Posted by sylla1 View Post
Some elementary English: (Merriam-Webster)

AFAIK the concept is equally valid in Italian or any other language I'm aware of.

Just check out any sphere.
(Because no infinite sphere is known)

Click the image to open in full size.

This (or any other) sphere naturally has no boundaries, but equally naturally it has limits: in geometrical terms, its surface.
Ok, but this comment is out of context. Probably it's again my fault I'm not able to explain well ...

I'm not asking about the limits of the sphere [it's obvious that the surface of a sphere is its limit ...].

I'm wondering about the limits of the surface of the sphere [the 2D membrane limiting its volume].

The universe is a space-time curved in an hyperdimension like the surface of the sphere [a 2D membrane] is curved in the third dimension.
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Old November 29th, 2012, 11:36 AM   #258
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Quote:
Originally Posted by AlpinLuke View Post
Well, not when [temporally], but where [geometrically]. Temporally, you're absolutely right ...
And geometrically too.
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Old November 29th, 2012, 11:38 AM   #259
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Quote:
Originally Posted by AlpinLuke View Post
You haven't understood the point.



Ok, but this comment is out of context. Probably it's again my fault I'm not able to explain well ...

I'm not asking about the limits of the sphere [it's obvious that the surface of a sphere is its limit ...].

I'm wondering about the limits of the surface of the sphere [the 2D membrane limiting its volume].

The universe is a space-time curved in an hyperdimension like the surface of the sphere [a 2D membrane] is curved in the third dimension.
"Out of context" just in your educated opinion now, ostensibly not so just some posts ago, and certainly not according to Dr. Hawking and so many other authors using this illustrative analogy.

Hint: you are simply making a semantic confusion between "boundary" & "limit", definitely not any synonymous terms within this context.
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Old November 29th, 2012, 11:40 AM   #260

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In other words ... always honoring the simplicity of the OP ...

walking along the surface of a sphere ... will I meet an edge or a boundary or a limit of any kind ... or will I be able to walk and walk and walk ... passing may times from the same points [of course], but will I meet a stop?
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