Big Bang - Explosive or dimensional uncurling?

What's the most widely accepted position on this. Was the Big Bang a
humongous explosion, or was it a matter of three spatial dimensions
uncurling? If this was an explosion, what did things expand into? Were
the three spatial dimensions we now perceive always there, but
completely devoid of any matter other than the point at which the Big
Bang occurred?

Gordon

"Antares 531" wrote in message
...
What's the most widely accepted position on this. Was the Big Bang a
humongous explosion, or was it a matter of three spatial dimensions
uncurling?

Neither - not 'uncurling' but 'expanding'

If this was an explosion, what did things expand into? Were
the three spatial dimensions we now perceive always there, but
completely devoid of any matter other than the point at which the Big
Bang occurred?

No, there wasn't an 'empty universe' there beforehand. The dimensions came
into existence at the same time as the universe.

That's the generally accepted model anyhow.
Google "Ned Wright's cosmology tutorial" for a comprehensive overview. It's
not simple though!

Dear Antares 531:

On Feb 14, 3:48*pm, Antares 531 wrote:
What's the most widely accepted position on this. Was the Big Bang a
humongous explosion, or was it a matter of three spatial dimensions
uncurling? If this was an explosion, what did things expand into? Were
the three spatial dimensions we now perceive always there, but
completely devoid of any matter other than the point at which the Big
Bang occurred?

"OG" has the right of it.
http://www.astro.ucla.edu/~wright/cosmolog.htm

David A. Smith

dlzc wrote:
Dear Antares 531:

On Feb 14, 3:48 pm, Antares 531 wrote:
What's the most widely accepted position on this. Was the Big Bang a
humongous explosion, or was it a matter of three spatial dimensions
uncurling? If this was an explosion, what did things expand into? Were
the three spatial dimensions we now perceive always there, but
completely devoid of any matter other than the point at which the Big
Bang occurred?

"OG" has the right of it.
http://www.astro.ucla.edu/~wright/cosmolog.htm

David A. Smith

This quote is new to me:

Big Bang Nucleosynthesis
"Most lithium and beryllium is produced by cosmic ray collisions
breaking up some of the carbon produced in stars."
http://www.astro.ucla.edu/~wright/BBNS.html

I thought most Lithium was produced in the Big Bang? And that all of the
Lithium we have now is all that we'll ever have.

Yousuf Khan

Antares 531 wrote:
What's the most widely accepted position on this. Was the Big Bang a
humongous explosion, or was it a matter of three spatial dimensions
uncurling? If this was an explosion, what did things expand into? Were
the three spatial dimensions we now perceive always there, but
completely devoid of any matter other than the point at which the Big
Bang occurred?

Even if it were dimensional uncurling, you'd still need the energy of an
explosion to uncurl them.

Yousuf Khan

On Thu, 18 Feb 2010 08:44:09 -0500, Yousuf Khan
wrote:

Antares 531 wrote:
What's the most widely accepted position on this. Was the Big Bang a
humongous explosion, or was it a matter of three spatial dimensions
uncurling? If this was an explosion, what did things expand into? Were
the three spatial dimensions we now perceive always there, but
completely devoid of any matter other than the point at which the Big
Bang occurred?

Even if it were dimensional uncurling, you'd still need the energy of an
explosion to uncurl them.

Yousuf Khan

This seems right, unless there is some other means, yet unknown,
hiding in the background. Gordon

On Feb 18, 8:53*am, Antares 531 wrote:
On Thu, 18 Feb 2010 08:44:09 -0500, Yousuf Khan

wrote:
Antares 531 wrote:
What's the most widely accepted position on this. Was the Big Bang a
humongous explosion, or was it a matter of three spatial dimensions
uncurling? If this was an explosion, what did things expand into? Were
the three spatial dimensions we now perceive always there, but
completely devoid of any matter other than the point at which the Big
Bang occurred?

Even if it were dimensional uncurling, you'd still need the energy of an
explosion to uncurl them.

* *Yousuf Khan

This seems right, unless there is some other means, yet unknown,
hiding in the background. * *Gordon

One way to look at it is that the Universe is infinite now, but in the
past when the BB happened, was the Universe finite? The answer is that
the Universe was probably already infinite, even at zero time. The
point from which our section of the Universe grew out of is just the
visible part of a Big Bang that happened in infinite places.

In fact, the only dimension that we have any sort of absolute endpoint
for is the Time dimension. And that endpoint is the Big Bang. Time may
go on forever after this, so there will be no finishing endpoint, but
there is a starting endpoint. So that indicates to me that Time is the
only dimension that got uncurled.

Yousuf Khan

On Thu, 18 Feb 2010 22:49:11 -0800 (PST), YKhan
wrote:

On Feb 18, 8:53*am, Antares 531 wrote:
On Thu, 18 Feb 2010 08:44:09 -0500, Yousuf Khan

wrote:
Antares 531 wrote:
What's the most widely accepted position on this. Was the Big Bang a
humongous explosion, or was it a matter of three spatial dimensions
uncurling? If this was an explosion, what did things expand into? Were
the three spatial dimensions we now perceive always there, but
completely devoid of any matter other than the point at which the Big
Bang occurred?

Even if it were dimensional uncurling, you'd still need the energy of an
explosion to uncurl them.

* *Yousuf Khan

This seems right, unless there is some other means, yet unknown,
hiding in the background. * *Gordon

One way to look at it is that the Universe is infinite now, but in the
past when the BB happened, was the Universe finite? The answer is that
the Universe was probably already infinite, even at zero time. The
point from which our section of the Universe grew out of is just the
visible part of a Big Bang that happened in infinite places.

In fact, the only dimension that we have any sort of absolute endpoint
for is the Time dimension. And that endpoint is the Big Bang. Time may
go on forever after this, so there will be no finishing endpoint, but
there is a starting endpoint. So that indicates to me that Time is the
only dimension that got uncurled.

Yousuf Khan

This is a interesting perspective, but I wonder if maybe the universe
may eventually collapse back to the point of origin. If this could
happen, we might still see it expanding within our visible horizon but
it may be already collapsing out beyond our visible horizon. This
would be something like a geyser erupting. The water near the source
would be moving upward while the water on up near the top would be
slowing and eventually reversing, without any discernable effects on
the velocity near the source.

Gordon

GWD wrote:
These are mind boggling concepts to the layman. I have to accept that
those who study this know what they are talking about. Some thoughts
spring to mind though:
There were no dimensions before the big bang. Does that mean that
nothing existed then? I'm imagining the exitance of balls of
compressed matter of mind bogglingly huge mass and mind bogglingly
small diameter, aggregating until a super critical phase is reached,
then exploding. Therefore the universe is finite and exists against an
infinite background of nothing.

Probably at that moment, mass itself didn't exist, it was all just pure
energy, which then precipitated down into particles, which acquired
mass. Energy can be concentrated to as much degree as you like.

Yousuf Khan

Antares 531 wrote:
This is a interesting perspective, but I wonder if maybe the universe
may eventually collapse back to the point of origin. If this could
happen, we might still see it expanding within our visible horizon but
it may be already collapsing out beyond our visible horizon. This
would be something like a geyser erupting. The water near the source
would be moving upward while the water on up near the top would be
slowing and eventually reversing, without any discernable effects on
the velocity near the source.

Gordon

I understand the point that you're trying to make, but it's not actually
the right analogy. Every particle in a geyser is actually slowing down
with gravity, the moment it leaves its source. So even though the liquid
is moving upward, it's constantly decelerating (negative acceleration),
it doesn't just suddenly slow down and start moving downward when it
gets to the top. The geyser is given one big acceleration upward by its
source, but from that point onward gravity takes over and decelerates it
constantly.

This is different from what we see with our Universe. We are seeing it
not actually accelerating rather than decelerating.

Yousuf Khan