Discussion in 'Electronic Design' started by RichD, Dec 23, 2008.

1. ### RichDGuest

The usual analogy to describe the geometry of spacetime
is an expanding balloon. The surface is 2-D, closed, warped
in a 3rd dimension, inaccessible to the balloonists. However,
the ballon has a center - in the 3rd dimension.

Now, extend this picture to our expanding 3-D universe;
can we compute the 'radius', the distance to the center,
in the 4th space dimension? Analogous to the balloon
model, it should be the same for all observers.

And that would educe a circumference, would it not?

2. ### Sam WormleyGuest

No Center
http://www.astro.ucla.edu/~wright/nocenter.html
http://www.astro.ucla.edu/~wright/infpoint.html

Also see Ned Wright's Cosmology Tutorial
http://www.astro.ucla.edu/~wright/cosmolog.htm
http://www.astro.ucla.edu/~wright/cosmology_faq.html
http://www.astro.ucla.edu/~wright/CosmoCalc.html

WMAP: Foundations of the Big Bang theory
http://map.gsfc.nasa.gov/m_uni.html

WMAP: Tests of Big Bang Cosmology
http://map.gsfc.nasa.gov/m_uni/uni_101bbtest.html

3. ### David L. JonesGuest

Yep, and the answer is 42 astronomical cubits.

Dave.

4. ### Guest

Now, extend this picture to our expanding 3-D universe;
Considering the universe as a sphere it certainly should have a center.
However considering gravity, expansion and other things we don't know about
yet things might not be as we thought they were
Maybe we can't exist outside the visable universe. Or it's just as any
ordinary space. But VERY empty

Now if it would be possible to travel outside the visable universe. There's
something interesting to discover.

5. ### Guest

Correction; the internal and external volumes (and the center of
course) are inaccessible, the surface is all that's accessible.
Sure, why not? The yardstick will be the path of a photon from the
Big Bang to your eye (in the 5-dimensional space in which our
expanding 4D universe is expanding) and that path will resemble an
Archimedean spiral. However it will be slightly altered by such things
as Cosmic Inflation early on, when the expansion rate increased
greatly for a while.
Yeah, but we can never see but a small bit of it.

Mark L. Fergerson

6. ### N:dlzc D:aol T:com \(dlzc\)Guest

Dear RichD:

Representing space.
.... Time.
The "Big Bang".
I believe the "distance" has been calculated to be 14.5 Gy (may
have moved again).
.... at any given *now*, with the usual synchronization problems.
Not a unique circumference, since there is no guarantee this
Universe is hyperspherical. Might be a dang torus.

David A. Smith

7. ### Guest

I think that the point is that the universe looks as if it is between
13.6 and 13.8 billion year old

http://en.wikipedia.org/wiki/Age_of_the_universe

so you can't get anyplace that further from us than 13.8 billion ight
years, and no place further away that that can get to us, so that we
can say anything useful about more remote areas, and they can't affect
us.

In that sense, we do live in a gold-fish bowl (albeit it a rather
large one).

<snip>

8. ### Guest

People have looked for evidence that we can see the same bit of space
anything much.

My understanding was that the smart money was on the 4-D equivalent of
the saddle-shaped geometry, but I can't remember why.

http://en.wikipedia.org/wiki/Shape_of_the_Universe

9. ### MooseFETGuest

It appears that the universe is finite but doesn't have a boundary in
all 4 dimensions. You need to consider the 5th dimension to be able
to say that there is something we could call a center.

I would argue that the universe must be finite for the following
reason: Consider the location and speed of just one electron. This
information must be stored somehow. From quantum mechanics we know
that there is a limit on the resolution. From Einstein we know that
the speed has an upper limit. The only remaining number that could be
infinite is the position in an infinite universe. If this was the
case, the number of bits would be infinite. From Shannon, we know
that it takes energy for each bit that you store. From Einstein, we
know that this energy would have mass. From this, I claim that an
electron in an infinite universe would have infinite mass.

Nice crack pot theory. Huh?

10. ### krwGuest

How does that work? 6 x 9 x 1 Astronomical Cubits? 6 x 3 x 3 AC?

11. ### Guest

The radius of the universe is infinite, the diameter is finite.

12. ### Sam WormleyGuest

No Center
http://www.astro.ucla.edu/~wright/nocenter.html
http://www.astro.ucla.edu/~wright/infpoint.html

Also see Ned Wright's Cosmology Tutorial
http://www.astro.ucla.edu/~wright/cosmolog.htm
http://www.astro.ucla.edu/~wright/cosmology_faq.html
http://www.astro.ucla.edu/~wright/CosmoCalc.html

WMAP: Foundations of the Big Bang theory
http://map.gsfc.nasa.gov/m_uni.html

WMAP: Tests of Big Bang Cosmology
http://map.gsfc.nasa.gov/m_uni/uni_101bbtest.html

13. ### Uncle AlGuest

No. The outside of a black hole's event horizon has a finite diameter
implied pole to pole. The inside diameter is infinite, passing
through the center singularity. Think "tardis" but with a roomier
interior.

Tell us how to locate paired interior poles of an event horizon.

Kandor.

Cheers!
Rich

15. ### Dirk Bruere at NeoPaxGuest

Since the 4th dimension is time, by your reasoning the distance to the
centre is 13.7 billion years, give or take.

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.onetribe.me.uk/wordpress/?cat=5 - Our podcasts on weird stuff

16. ### krwGuest

Now *YOU* sound like the creationist. ;-) Who cares if there was
one, or more than one "big bang"? Such things are unknowable thus
unimportant. Who says there is only one universe? Who cares?
Can't reach us, or it isn't a "big bang". Again, you're setting
yourself up as the creationist because *you* can't see the other
universes, yet believe they exist (or don't).
That simply means the bang wasn't perfectly
"uniform".
Why?

17. ### Paul E. SchoenGuest

The further we look in any direction, the older the objects are, and if
they are as old as the universe, they were part of the big bang, where
space-time was in its most contracted state. Thus, although we appear to be
in the center of a spherical universe, we actually are looking at the
center when we look in any direction. So, in a sense, we (or any observer)
are located on the inside surface of an expanding sphere, and we cannot
look outside of this sphere (as it is undefined future space-time into
which the universe is expanding).

All light from the time of the big bang and thereafter is contained within
this sphere and is gravitationally bent so that other elements of the
universe located on other points of the sphere appear to be located at
specific points in space-time which we can quantify by three-dimensional
spatial vectors as well as the time vector. This contributes to the
distortion, so that the oldest objects appear to be furthest apart (in
spatial sense), while they are at their closest proximity to each other in
time.

Otherwise, there is the paradox that two objects in deepest space, but
spatially opposite each other, would appear to be separated by twice the
light-years of the age of the universe, so they would have had to exceed
the speed of light to be located where they appear. But they are actually
in close proximity to each other and are simply seen where they were at the
beginning of space-time, but gravitational lensing creates the distortion
that makes them appear to be impossibly far apart.

At least that's my philosophical view of things...

Paul

18. ### Sam WormleyGuest

The further we look out... the further back in time we peer to
younger and younger objects.

Thus, although we appear to be
Every point is just as much the center as any other point.

No Center
http://www.astro.ucla.edu/~wright/nocenter.html
http://www.astro.ucla.edu/~wright/infpoint.html

19. ### hansonGuest

......... ahahaha... AHAHAHAHAHA.....
hanson wrote:
ahahahaha... AHAHAHAHA... Thanks for the laughs, guys!
ahahaha... ahahahanson

20. ### krwGuest

So you mock "creationists" by making up silly stories with even less
internal consistency, history, or teaching?
Of which you made up out of whole cloth.
Perhaps it doesn't hurt, but it certainly help no one either.
....and that would be useful how?