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Loop Gravity and the Bouncing Universe



 
 
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  #1  
Old October 15th 08, 08:13 PM posted to alt.astronomy
Double-A[_2_]
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Default Loop Gravity and the Bouncing Universe

My fellow cosmologists, the October issue of the Scientific American
has a very good article on a new theory of quantum gravity, Loop
Gravity, which is very interesting. It talks about theoretical
"atoms" of space-time that are little spheres the diameter a Planck-
length. These atoms of space-time can only hold so much energy, and
then their gravity turns repulsive. So point singularities can never
form, and a collapsing universe will never reach a singularity, but
will only reach a state of extreme density, at which time the
repulsive gravity will make it bounce back in an apparent Big Bang.
The model shows that little information could come through this big
crunch because of quantum scrambling. The theory predicts that
different frequencies of light may travel at slightly different
speeds! (Haven't I been saying that?) Anyway, it's a good read and
worth pondering. Any thoery that gets rid of singularities is a step
forward. You can also read it at

http://www.sciam.com/article.cfm?id=...-or-big-bounce

Double-A

  #2  
Old October 16th 08, 05:03 AM posted to alt.astronomy
oldcoot
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Posts: 1,357
Default Loop Gravity and the Bouncing Universe

On Oct 15, 12:13 pm, Double-A wrote:
My fellow cosmologists, the October issue of the Scientific American
has a very good article on a new theory of quantum gravity, Loop
Gravity, which is very interesting. It talks about theoretical
"atoms" of space-time that are little spheres the diameter a Planck-
length. These atoms of space-time can only hold so much energy, and
then their gravity turns repulsive. So point singularities can never
form, and a collapsing universe will never reach a singularity, but
will only reach a state of extreme density, at which time the
repulsive gravity will make it bounce back in an apparent Big Bang.
The model shows that little information could come through this big
crunch because of quantum scrambling. The theory predicts that
different frequencies of light may travel at slightly different
speeds! (Haven't I been saying that?) Anyway, it's a good read and
worth pondering. Any thoery that gets rid of singularities is a step
forward. You can also read it at

http://www.sciam.com/article.cfm?id=...-or-big-bounce

Interesting piece, AA. It's actually a refined variation of the
oscillating/reciprocating and 'eternal return' models. And it's
interesting that the author speaks of "space-time atoms", which would
be a rough corollary to our sub-Planckian 'granulons' comprizing the
SPED. However, the euphamism "space-time" is still mandated because
the VSP forbids existance of the SPED.
Then juxtapose this model alongside the CBB
model which recognizes two distinct referance frames : the restricted
'inside' frame which perceives only a singular 'Bang' bouncing back
from a singular 'crunch' (like a single power stroke of a piston).
Then there's the overarching 'outside' frame from whence the whole
Process is seen continuously running, like a gas turbine.
http://community-2.webtv.net/oldcoot/ContinuousBigBang/

This is why the CBB model subsumes but *does not negate* the singular
BigBang (or singular Big Bounce) idea. Hell, there's even a (singular)
Big Bloom idea floating around the web. :-)





  #3  
Old October 16th 08, 04:45 PM posted to alt.astronomy
Painius Painius is offline
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First recorded activity by SpaceBanter: Jan 2007
Posts: 4,144
Default Loop Gravity and the Bouncing Universe

"oldcoot" wrote in message...
...
On Oct 15, 12:13 pm, Double-A wrote:

My fellow cosmologists, the October issue of the Scientific American
has a very good article on a new theory of quantum gravity, Loop
Gravity, which is very interesting. It talks about theoretical
"atoms" of space-time that are little spheres the diameter a Planck-
length. These atoms of space-time can only hold so much energy, and
then their gravity turns repulsive. So point singularities can never
form, and a collapsing universe will never reach a singularity, but
will only reach a state of extreme density, at which time the
repulsive gravity will make it bounce back in an apparent Big Bang.
The model shows that little information could come through this big
crunch because of quantum scrambling. The theory predicts that
different frequencies of light may travel at slightly different
speeds! (Haven't I been saying that?) Anyway, it's a good read and
worth pondering. Any thoery that gets rid of singularities is a step
forward. You can also read it at

http://www.sciam.com/article.cfm?id=...-or-big-bounce


Interesting piece, AA. It's actually a refined variation of the
oscillating/reciprocating and 'eternal return' models. And it's
interesting that the author speaks of "space-time atoms", which would
be a rough corollary to our sub-Planckian 'granulons' comprizing the
SPED. However, the euphamism "space-time" is still mandated because
the VSP forbids existance of the SPED.
Then juxtapose this model alongside the CBB
model which recognizes two distinct referance frames : the restricted
'inside' frame which perceives only a singular 'Bang' bouncing back
from a singular 'crunch' (like a single power stroke of a piston).
Then there's the overarching 'outside' frame from whence the whole
Process is seen continuously running, like a gas turbine.
http://community-2.webtv.net/oldcoot/ContinuousBigBang/

This is why the CBB model subsumes but *does not negate* the singular
BigBang (or singular Big Bounce) idea. Hell, there's even a (singular)
Big Bloom idea floating around the web. :-)


So if LQG ever takes off as the Primo, Mainstream
"Quantum Theory of Gravity", you could always change
the name of Wolter's to "Continuous Big BOUNCE" and
still keep the same initials! ("CB BLOOM" wouldn't do
because it's inconsistent with LQG.)

LQG's been around for awhile, BTW, starting back in
'86. SA is really reaching when it publishes a story on
quantum gravity. I love it. I still get SA here at the
house every month.

happy days and...
starry starry nights!

--
Indelibly yours,
Paine Ellsworth

P.S. "Prediction is very difficult, especially about the
future."
Niels Bohr


P.P.S.: http://yummycake.secretsgolden.com
http://garden-of-ebooks.blogspot.com
http://painellsworth.net


  #4  
Old October 16th 08, 08:12 PM posted to alt.astronomy
Double-A[_2_]
external usenet poster
 
Posts: 1,720
Default Loop Gravity and the Bouncing Universe

On Oct 15, 9:03*pm, oldcoot wrote:
On Oct 15, 12:13 pm, Double-A wrote:



My fellow cosmologists, the October issue of the Scientific American
has a very good article on a new theory of quantum gravity, Loop
Gravity, which is very interesting. *It talks about theoretical
"atoms" of space-time that are little spheres the diameter a Planck-
length. *These atoms of space-time can only hold so much energy, and
then their gravity turns repulsive. *So point singularities can never
form, and a collapsing universe will never reach a singularity, but
will only reach a state of extreme density, at which time the
repulsive gravity will make it bounce back in an apparent Big Bang.
The model shows that little information could come through this big
crunch because of quantum scrambling. *The theory predicts that
different frequencies of light may travel at slightly different
speeds! *(Haven't I been saying that?) *Anyway, it's a good read and
worth pondering. *Any thoery that gets rid of singularities is a step
forward. *You can also read it at


http://www.sciam.com/article.cfm?id=...-or-big-bounce


Interesting piece, AA. It's actually a refined variation of the
oscillating/reciprocating and 'eternal return' models. And it's
interesting that the author speaks of "space-time atoms", which would
be a rough corollary to our sub-Planckian 'granulons' comprizing the
SPED.



Right.


However, the euphamism "space-time" is still mandated because
the VSP forbids existance of the SPED.



This doesn't sound like void space to me. Also its talking about
photons interacting with the space-time atoms doesn't sound like void
space.


* * * * * * * * * * * Then juxtapose this model alongside the CBB
model which recognizes two distinct referance frames : the restricted
'inside' frame which perceives only a singular 'Bang' bouncing back
from a singular 'crunch' (like a single power stroke of a *piston).
Then there's the overarching 'outside' frame from whence the whole
Process is seen continuously running, like a gas turbine.http://community-2.webtv.net/oldcoot/ContinuousBigBang/

This is why the CBB model subsumes but *does not negate* the singular
BigBang (or singular Big Bounce) idea. Hell, there's even a (singular)
Big Bloom idea floating around the web. *



I really like the way it theorizes a big crunch and bang while
avoiding a singularity.

Double-A

  #5  
Old October 16th 08, 08:41 PM posted to alt.astronomy
oldcoot
external usenet poster
 
Posts: 1,357
Default Loop Gravity and the Bouncing Universe

On Oct 16, 12:12*pm, Double-A wrote:
oldcoot wrote:

...the euphamism "space-time" is still mandated because
the VSP forbids existance of the SPED.


This doesn't sound like void space to me. *Also its talking about
photons interacting with the space-time atoms doesn't sound like void
space.

When Uncle Albert kicked out the "aether", he had to substitute
something for it. The mathematical abstraction "space-time" became its
surrogate. That way, space could still be an abstract 'something'
while abiding by the mandate that there is "no medium". So when
somebody talks about "space-time atoms", this same edict is adhered
to. It forbits existance of a literal spatial medium, either the
archaic "aether" or the SPED.

...the CBB model subsumes but *does not negate* the singular
BigBang (or singular Big Bounce) idea. Hell, there's even a (singular)
Big Bloom idea floating around the web. *


I really like the way it theorizes a big crunch and bang while
avoiding a singularity.

Actually it postulates a 'squashed out', spinning disc similar to the
'ring singularity' of the Kerr BH model.

  #6  
Old October 17th 08, 09:08 PM posted to alt.astronomy
Double-A[_2_]
external usenet poster
 
Posts: 1,720
Default Loop Gravity and the Bouncing Universe

On Oct 16, 12:41*pm, oldcoot wrote:
On Oct 16, 12:12*pm, Double-A wrote: oldcoot wrote:

...the euphamism "space-time" is still mandated because
the VSP forbids existance of the SPED.


This doesn't sound like void space to me. *Also its talking about
photons interacting with the space-time atoms doesn't sound like void
space.


When Uncle Albert kicked out the "aether", he had to substitute
something for it. The mathematical abstraction "space-time" became its
surrogate. That way, space could still be an abstract 'something'
while abiding by the mandate that there is "no medium". So when
somebody talks about "space-time atoms", this same edict is adhered
to. It forbits existance of a literal spatial medium, either the
archaic "aether" or the SPED.



Einstein's only objection to the classical aether was that it couldn't
be used as a rest frame against which to mesure absolute motion. (The
quote is out there if only I had time to find it.) By theorizing
space-time atoms, it would seem to me they would have some local
existence, if they interact with photons, and contain defferent
amounts of energt depending on location. I don't see how he can do
this without by doing so establishing an absolute rest frame. If
space has atoms, then the objects in space would have velocities
relative to any particlular space-time atom. The author holds to
relativity, but if he is establishing an abolute reference frame by
defining these atoms, then relativity will go out the window!


...the CBB model subsumes but *does not negate* the singular
BigBang (or singular Big Bounce) idea. Hell, there's even a (singular)
Big Bloom idea floating around the web. *


I really like the way it theorizes a big crunch and bang while
avoiding a singularity.


Actually it postulates a 'squashed out', spinning disc similar to the
'ring singularity' of the Kerr BH model.



So I guess "spin is in"! (I couldn't resist.)

Double-A

  #7  
Old October 18th 08, 12:30 AM posted to alt.astronomy
Painius Painius is offline
Banned
 
First recorded activity by SpaceBanter: Jan 2007
Posts: 4,144
Default Loop Gravity and the Bouncing Universe

"Double-A" wrote in message...
...
On Oct 16, 12:41 pm, oldcoot wrote:
On Oct 16, 12:12 pm, Double-A wrote:
oldcoot wrote:

...the euphamism "space-time" is still mandated because
the VSP forbids existance of the SPED.

This doesn't sound like void space to me. Also its talking about
photons interacting with the space-time atoms doesn't sound like void
space.


When Uncle Albert kicked out the "aether", he had to substitute
something for it. The mathematical abstraction "space-time" became its
surrogate. That way, space could still be an abstract 'something'
while abiding by the mandate that there is "no medium". So when
somebody talks about "space-time atoms", this same edict is adhered
to. It forbits existance of a literal spatial medium, either the
archaic "aether" or the SPED.


Einstein's only objection to the classical aether was that it couldn't
be used as a rest frame against which to mesure absolute motion. (The
quote is out there if only I had time to find it.) . . .

Double-A


Here's the only "sourced" quote i could find...

"We may assume the existence of an aether; only we
must give up ascribing a definite state of motion to it,
i.e. we must by abstraction take from it the last
mechanical characteristic which Lorentz had still left it."

Source: On the irrelevance of the luminiferous aether
hypothesis to physical measurements, in an address at
the University of Leiden (May 5, 1920)

happy days and...
starry starry nights!

--
Indelibly yours,
Paine Ellsworth

P.S. (to a young physics student) "Your theory is
crazy, but it's not crazy enough to be true."
Niels Bohr


P.P.S.: http://yummycake.secretsgolden.com
http://garden-of-ebooks.blogspot.com
http://painellsworth.net


  #8  
Old October 18th 08, 08:04 PM posted to alt.astronomy
Double-A[_2_]
external usenet poster
 
Posts: 1,720
Default Loop Gravity and the Bouncing Universe

On Oct 17, 4:30*pm, "Painius" wrote:
"Double-A" wrote in message...

...





On Oct 16, 12:41 pm, oldcoot wrote:
On Oct 16, 12:12 pm, Double-A wrote:
oldcoot wrote:


...the euphamism "space-time" is still mandated because
the VSP forbids existance of the SPED.


This doesn't sound like void space to me. Also its talking about
photons interacting with the space-time atoms doesn't sound like void
space.


When Uncle Albert kicked out the "aether", he had to substitute
something for it. The mathematical abstraction "space-time" became its
surrogate. That way, space could still be an abstract 'something'
while abiding by the mandate that there is "no medium". So when
somebody talks about "space-time atoms", this same edict is adhered
to. It forbits existance of a literal spatial medium, either the
archaic "aether" or the SPED.


Einstein's only objection to the classical aether was that it couldn't
be used as a rest frame against which to mesure absolute motion. *(The
quote is out there if only I had time to find it.) . . .


Double-A


Here's the only "sourced" quote i could find...

*"We may assume the existence of an aether; only we
*must give up ascribing a definite state of motion to it,
*i.e. we must by abstraction take from it the last
*mechanical characteristic which Lorentz had still left it."

*Source: *On the irrelevance of the luminiferous aether
*hypothesis to physical measurements, in an address at
*the University of Leiden (May 5, 1920)

happy days and...
* *starry starry nights!

--
Indelibly yours,
Paine Ellsworth



Yes, that's the quote, and the final lines at the end:

"But this ether may not be thought of as endowed with the quality
characteristic of ponderable inedia, as consisting of parts which may
be tracked through time. The idea of motion may not be applied to it."

http://www.tu-harburg.de/rzt/rzt/it/Ether.html

The detection of the Earth's rotation by interferometer is called the
Sagnac effect:

"The first ring interferometry experiment aimed at observing the
correlation of angular velocity and phase-shift was performed by the
Frenchman Georges Sagnac in 1913, which is why the effect is named for
him. Its purpose was to detect "the effect of the relative motion of
the ether". An experiment conducted in 1911 by Francis Harress, aimed
at making measurements of Fresnel drag of light propagating through
moving glass, was later recognized as actually constituting a Sagnac
experiment. Harress had ascribed the "unexpected bias" to something
else.

In 1926 a very ambitious ring interferometry experiment was set up by
Albert Michelson and Henry Gale. The aim was to find out whether the
rotation of the Earth has an effect on the propagation of light in the
vicinity of the Earth. The Michelson-Gale experiment was a very large
ring interferometer, (a perimeter of 1.9 kilometer), large enough to
detect the angular velocity of the Earth. The outcome of the
experiment was that the angular velocity of the Earth as measured by
astronomy was confirmed to within measuring accuracy. The ring
interferometer of the Michelson-Gale experiment was not calibrated by
comparison with an outside reference (which was not possible, because
the setup was fixed to the Earth). From its design it could be deduced
where the central interference fringe ought to be if there would be
zero shift. The measured shift was 230 parts in 1000, with an accuracy
of 5 parts in 1000. The predicted shift was 237 parts in 1000."

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

Double-A



  #9  
Old October 18th 08, 09:45 PM posted to alt.astronomy
Painius Painius is offline
Banned
 
First recorded activity by SpaceBanter: Jan 2007
Posts: 4,144
Default Loop Gravity and the Bouncing Universe

"Double-A" wrote in message...
...
On Oct 17, 4:30 pm, "Painius" wrote:
"Double-A" wrote in message...
...
On Oct 16, 12:41 pm, oldcoot wrote:
On Oct 16, 12:12 pm, Double-A wrote:
oldcoot wrote:

...the euphamism "space-time" is still mandated because
the VSP forbids existance of the SPED.

This doesn't sound like void space to me. Also its talking about
photons interacting with the space-time atoms doesn't sound like
void
space.

When Uncle Albert kicked out the "aether", he had to substitute
something for it. The mathematical abstraction "space-time" became
its
surrogate. That way, space could still be an abstract 'something'
while abiding by the mandate that there is "no medium". So when
somebody talks about "space-time atoms", this same edict is adhered
to. It forbits existance of a literal spatial medium, either the
archaic "aether" or the SPED.

Einstein's only objection to the classical aether was that it couldn't
be used as a rest frame against which to mesure absolute motion. (The
quote is out there if only I had time to find it.) . . .


Here's the only "sourced" quote i could find...

"We may assume the existence of an aether; only we
must give up ascribing a definite state of motion to it,
i.e. we must by abstraction take from it the last
mechanical characteristic which Lorentz had still left it."

Source: On the irrelevance of the luminiferous aether
hypothesis to physical measurements, in an address at
the University of Leiden (May 5, 1920)


Yes, that's the quote, and the final lines at the end:

"But this ether may not be thought of as endowed with the quality
characteristic of ponderable inedia, as consisting of parts which may
be tracked through time. The idea of motion may not be applied to it."

http://www.tu-harburg.de/rzt/rzt/it/Ether.html

The detection of the Earth's rotation by interferometer is called the
Sagnac effect:

"The first ring interferometry experiment aimed at observing the
correlation of angular velocity and phase-shift was performed by the
Frenchman Georges Sagnac in 1913, which is why the effect is named for
him. Its purpose was to detect "the effect of the relative motion of
the ether". An experiment conducted in 1911 by Francis Harress, aimed
at making measurements of Fresnel drag of light propagating through
moving glass, was later recognized as actually constituting a Sagnac
experiment. Harress had ascribed the "unexpected bias" to something
else.

In 1926 a very ambitious ring interferometry experiment was set up by
Albert Michelson and Henry Gale. The aim was to find out whether the
rotation of the Earth has an effect on the propagation of light in the
vicinity of the Earth. The Michelson-Gale experiment was a very large
ring interferometer, (a perimeter of 1.9 kilometer), large enough to
detect the angular velocity of the Earth. The outcome of the
experiment was that the angular velocity of the Earth as measured by
astronomy was confirmed to within measuring accuracy. The ring
interferometer of the Michelson-Gale experiment was not calibrated by
comparison with an outside reference (which was not possible, because
the setup was fixed to the Earth). From its design it could be deduced
where the central interference fringe ought to be if there would be
zero shift. The measured shift was 230 parts in 1000, with an accuracy
of 5 parts in 1000. The predicted shift was 237 parts in 1000."

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

Double-A


I don't understand. As a practical thing, the Sagnac effect
appears to be very useful. But the article didn't seem to
say whether or not Sagnac's effort to detect "the effect of
the relative motion of the ether" was considered a success
by his peers. Apparently, judging by an ensuing droppage
of any "ether", Sagnac's theoretical goal was not believed
to have been reached?

There is also no description of Michelson's conclusions he
drew from his and Gale's experiment. Did he and Gale
think that the ring interferometer was as ineffective as the
interferometer he used in his experiment with Morley?
(I.e., ineffective as to showing the existence of an ether?)

happy days and...
starry starry nights!

--
Indelibly yours,
Paine Ellsworth

P.S. (to a young physics student) "Your theory is
crazy, but it's not crazy enough to be true."
Niels Bohr


P.P.S.: http://yummycake.secretsgolden.com
http://garden-of-ebooks.blogspot.com
http://painellsworth.net


  #10  
Old October 19th 08, 04:14 PM posted to alt.astronomy
G=EMC^2 Glazier[_1_]
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Posts: 10,860
Default Loop Gravity and the Bouncing Universe

Double A Your post has me begging this question What is absolute
motion? TreBert

 




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