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View Full Version : Cosmic strings
blobrana 01-20-08, 08:06 PM A team of physicists and astronomers at the University of Sussex and Imperial College London have uncovered hints that there may be cosmic strings - lines of pure mass-energy - stretching across the entire Universe.
Read more (http://www.sussex.ac.uk/press_office/media/media662.shtml)
Jozen-Bo 01-21-08, 09:18 AM This is good news.
I have suspected for some time this univsers is woven, a tapestry of energy strings. The 'strings of time'...or referred to a long time ago as the 'strings of fate'. Funny, that there is talk of tearing the FABRIC of space!
I will have to investigate this carefully when I have more time, thanks!
cosmictraveler 01-21-08, 09:24 AM Nothing new....
In the 1960s, particle physicists reached towards something called a dual resonance model in an attempt to describe the strong nuclear force. The dual model was never that successful at describing particles, but it was understood by 1970 that the dual models were actually quantum theories of relativistic vibrating strings and displayed very intriguing mathematical behavior. Dual models came to be called string theory as a result.
But in 1971, a new type of quantum field theory came on the scene that explained the weak nuclear force by uniting it with electromagnetism into electroweak theory, and it was shown to be renormalizable. Then similar wisdom was applied to the strong nuclear force to yield quantum chromodynamics, or QCD, and this theory was also renormalizable.
Which left one force -- gravity -- that couldn't be turned into a renormalizable field theory no matter how hard anyone tried. One big problem was that classical gravitational waves carry spin J=2, so one should assume that a graviton, the quantum particle that carries the gravitational force, has spin J=2. But for J=2, 4 J - 8 + D = D, and so for D=4, the loop integral for the gravitational force would become infinite like the fourth power of momentum, as the momentum in the loop became infinite.
And that was just hard cheese for particle physicists, and for many years the best people worked on quantum gravity to no avail.
But the string theory that was once proposed for the strong interactions contained a massless particle with spin J=2.
In 1974 the question finally was asked: could string theory be a theory of quantum gravity?
The possible advantage of string theory is that the analog of a Feynman diagram in string theory is a two-dimensional smooth surface, and the loop integrals over such a smooth surface lack the zero-distance, infinite momentum problems of the integrals over particle loops.
In string theory infinite momentum does not even mean zero distance, because for strings, the relationship between distance and momentum is roughly likehe parameter a' (pronounced alpha prime) is related to the string tension, the fundamental parameter of string theory, by the relation
The above relation implies a minimum observable length for a quantum string theory.
More:
http://www.superstringtheory.com/basics/basic4a.html
blobrana 01-21-08, 09:55 AM Just like the large-scale frothy nature of the distribution of matter was discovered by plotting the redshift of galaxies, the plotting of gravitational lensed objects and abnormalities may reveal the signature of topological defects/cosmic strings.
http://en.wikipedia.org/wiki/Cosmic_string
Note: There is no direct connection between string theory and cosmic strings.
However, Superstrings could be stretched to intergalactic scales by inflation and could imitate the defects.
Jozen-Bo 01-21-08, 11:19 AM I didn't mean new news. I meant 'brought up the issue and somewhere to look' news.
BenTheMan 01-21-08, 12:10 PM This is good news.
I have suspected for some time this univsers is woven, a tapestry of energy strings. The 'strings of time'...or referred to a long time ago as the 'strings of fate'. Funny, that there is talk of tearing the FABRIC of space!
I will have to investigate this carefully when I have more time, thanks!
Jozen---
This is not what a cosmic string is. A cosmic string is a topological defect, sort of a nipple in space-time.
blobrana 01-21-08, 01:07 PM nipple in space-time.
Hum,
strangely, i read about somebody `twisting the nipples of spacetime` when they were describing the Gravity Probe experiment recently.
I normally describe the spacetime defects being similar to flaws in a diamond or ice.
BenTheMan 01-21-08, 03:20 PM I normally describe the spacetime defects being similar to flaws in a diamond or ice.
This might be a better description---effectively this is what a topological defect is...much like the boundaries between crystals in an amorphous solid. A better analogy is actually the differences in phases in a perfect fluid, like helium 3. I read a Nature letter recently that used helium 3 in a lab to create analogues of cosmic strings which would be left over from brane-anti-brane colisions.
Jozen-Bo 01-22-08, 08:13 AM BentheMan,
Originally Posted by Jozen-Bo
This is good news.
I have suspected for some time this univsers is woven, a tapestry of energy strings. The 'strings of time'...or referred to a long time ago as the 'strings of fate'. Funny, that there is talk of tearing the FABRIC of space!
I will have to investigate this carefully when I have more time, thanks! ”
Jozen---
This is not what a cosmic string is. A cosmic string is a topological defect, sort of a nipple in space-time.
I know that. just find it funny that we talk about strings so much. Where does one find the cosmic G-String (just joking) that goes well with that nipple in time?
My referral wasn't directly relating to cosmic strings, I do apoligize if I didn't make that clear. I was referring to the knowledge that all matter is 'woven' out of whirling energy- the center of the whirl might be called an equilibrium string when observed over time, if mapped out as a function it would graph a string within X,Y,Z space coordinates as the whirl's equilibrium position changes. Nothing new really.
blobrana 01-22-08, 04:51 PM Ripples in Spacetime
"Predicted in Einstein's General Theory of Relativity, gravitational waves are disturbances in the curvature of spacetime caused by the motions of matter."
Source (http://archive.ncsa.uiuc.edu/Cyberia/NumRel/GravWaves.html)
http://en.wikipedia.org/wiki/LIGO
blobrana 07-02-08, 04:52 AM "Physicists in the US and Singapore are the first to use light from distant galaxies to perform a systematic search for cosmic strings — massive structures that may have been created just after the Big Bang. Although the team has found no evidence of cosmic strings in the small patch of sky they surveyed, they have been able to set an upper limit on the mass per unit length of the strings."
Read more (http://physicsworld.com/cws/article/news/34826)
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