Setting a trap for gravity waves

Mar 19, 2014 by Paul Preuss
Setting a Trap for Gravity Waves
B-mode polarization of the cosmic microwave background radiation exhibits a distinctive 'curl,' either left or right-handed, imposed by the distortion of space as gravity waves moved through it. Credit: BICEP2 Collaboration

In 1996 Uros Seljak was a postdoc at Harvard, contemplating ways to extract information from the cosmic microwave background (CMB). The distribution of anisotropies, slight temperature differences, in the CMB had much to say about the large-scale structure of the universe. If it were also possible to detect the polarization of the CMB itself, however, a much wider window would be opened – polarization could even reveal the tracks of gravitational waves.

"Gravitational waves are distortions of space on a small scale, and have no consequence for the large-scale structure of the universe," says Seljak, now a professor of physics and astronomy at UC Berkeley and a faculty scientist in Berkeley Lab's Physics Division. "Both result from perturbations during inflation, but the seeds of large-scale structure are described by a scalar field, and by a tensor field."

Cosmologists already assumed that inflation theory was essentially correct: virtually instantaneous expansion after the big bang explained how regions of the universe never otherwise in contact had in fact started from the same initial conditions. Here was a way to test inflation directly.

Seljak posted a paper to arXiv (soon published in the Astrophysical Journal), becoming the first to predict how could be used to find CMB tensor signals, including gravitational waves. Marc Kamionkowski, Arthur Kosowsky, and Albert Stebbins of Fermilab independently posted their similar proposal shortly thereafter. In further work with Matias Zaldarriaga, Seljak named the E and B modes of CMB polarization, borrowing the symbols for light's electric and magnetic fields – scalar fields produce E-mode polarization; a gravitational tensor field can produce both.

Fast forward to the year 2000, when Adrian Lee, a professor of astrophysics at UC Berkeley and faculty scientist in the Lab's Physics Division, came up with the idea of suspending the widely used transition-edge sensor bolometer (TES), creating what he describes as "a trampoline that bounces when an energy pulse lands on it" – the more energy, the bigger the bounce.

Lee integrated suspended TESs with other functions in flat chips suitable for the focal planes of CMB telescopes. He proposed just such a telescope, the POLARBEAR experiment, initiated with support from Berkeley Lab's Laboratory Directed Research and Development (LDRD). BICEP2 and many other CMB telescopes also use these focal-plane chips.

On Monday, March 17, 2014, the BICEP2 collaboration grabbed the brass ring: first detection of B-mode polarization from gravitational waves, thus first direct evidence of inflation – a signal far stronger than most scientists had expected.

"We look forward to working with BICEP2 to refine their measurements," says Lee. "Until now, the best evidence for inflation was a slight 'tilt' in the CMB scalar field. POLARBEAR's higher resolution could detect a similar tilt in the tensor field, a double confirmation of inflation."

Among the many implications of the large B-mode signal, says Seljak: "It may force us in the direction of string theory. It also fits in with models of continuing that produce multiple universes."

Explore further: First hints of gravitational waves in the Big Bang's afterglow

More information: "Signature of Gravity Waves in Polarization of the Microwave Background." Uros Seljak, Matias Zaldarriaga. DOI: 10.1086/304123, arXiv:astro-ph/9608131 Submitted on 20 Aug 1996 (v1), last revised 2 Mar 1997.

"A Probe of Primordial Gravity Waves and Vorticity." Marc Kamionkowski, Arthur Kosowsky, Albert Stebbins Phys.Rev.Lett.78:2058-2061,1997 DOI: 10.1103/PhysRevLett.78.2058

"Measuring Polarization In Cosmic Microwave Background," Uros Seljak. arXiv:astro-ph/9608131, DOI: 10.1086/304123

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RichManJoe
not rated yet Mar 19, 2014
This is an amazing anouncement. Having studied electromagnetics and having worked in satellite communications, I understand how polarization can be measured. However, I do not understand the significance of the E and B polarizations, nor how these can be differentiated. Plus, I would further like to understand how these are generated by both the scalar and tensor perturbations. So as I don't have to take this on faith (ie. religion) can someone direct me to or develop a video / paper to describe this?
no fate
1.5 / 5 (8) Mar 19, 2014
This is an amazing anouncement. Having studied electromagnetics and having worked in satellite communications, I understand how polarization can be measured. However, I do not understand the significance of the E and B polarizations, nor how these can be differentiated. Plus, I would further like to understand how these are generated by both the scalar and tensor perturbations. So as I don't have to take this on faith (ie. religion) can someone direct me to or develop a video / paper to describe this?


No, they can't. All of the assertions regarding the mechanism for polarization associated with this announcement have zero experimental validation.

Take it on faith that in 1985 Polnarev was correct in his interpretation that the B mode polarization in the CMB would indicate primordial gravity waves.

Personally, I feel they have ran with an assumption that is going to result in alot of apologies. Not looking for a debate here, just rate it "1" and move on mainstreamers.
antialias_physorg
5 / 5 (9) Mar 19, 2014
However, I do not understand the significance of the E and B polarizations

Try this site
http://cosmology....Bpol.htm
While it doesn't incorporate the latest developments it explains the differences quite well.

how these can be differentiated

It's like in the Maxwell equations (that's why they chose "E" and "B", though we're not talking about electric/magnetic fields here) where an electric-field that has no magnetic component is characterised by divergence only while a magnetic field is characterized by curl (divB is zero). You can mathematically decompose any field into a superposition of linear and curl components (the E and B mode).
Scalar components cannot create curl. Only tensor components can (or vector components...but that's probably not significant)
russell_russell
not rated yet Mar 20, 2014
AP's link is very good.

Vision the sigmas from this research improving with every new data set.
When the features of the structures studied and observed improve, the "new physics"
will (eventually) turn to questions of how this information ("new physics") gave and give rise to the structures revealed so far.

This is aside from all the 'scoffing' chaperoning every journey of science.
AmritSorli
not rated yet Mar 20, 2014
how are related GW of big bang and GW which are comming from binary stars ?
Zachia
5 / 5 (1) Mar 20, 2014
how are related GW of big bang and GW which are comming from binary stars
The big bang related GWs are supposed to be inflated and frozen, the others not. Also, this infographic could make a distinction for you.
Bonusje
1 / 5 (1) May 14, 2014

"Gravitational waves are distortions of space on a small scale"

Rubish: Hubble deepspace Proofs Not any drop of distorsion by gravity is present and Not any coupling of gravity and light or radiation!
The big bang complotcommunity makes also the 3K up what Simply is the Temp from the Input of all triljons of Stars and Galaxies they Never Accounted for in this big bang theory.

" the best evidence for inflation was a .."

No evidence for a big bang exists But for a Steady State Universe There is.
Bonusje
1 / 5 (1) May 14, 2014
And GRAVITYWAVES CAN NOT exist E= mC2 Says.

Also even with supernova where quite some matter desintegrates never any gravityriple was found. Where also it takes a very lot of time even after supernova befor any pull of the Gravity out of an area fades away what influence or detection for far away concerns.

Even the frequent massive gravity changes more than of supernova mass loss of eachother very fast circling Stars are not even detected. And then there is the Moon the most influentual gravity sourche in our Neighbourhood not even noticed.

And there is this: http://twitlonger..._1s1o70u

So Debunked Busted!
Bonusje
1 / 5 (1) May 14, 2014
Also coupling of Space and anything is Not possible because Space can be Described as emptiness as Nothing and so that Nothing can Not couple at anything because it is like saying x y or z x0 = stays Zero
Bonusje
1 / 5 (1) May 14, 2014
It Can maby be Said : Space and Matter Rule eachother Out!

Or there is Space or there is Some Thing whatever matter or radiation.
Pejico
May 14, 2014
This comment has been removed by a moderator.
Bonusje
1 / 5 (1) May 14, 2014
Just a philosofical idea but did you ever think of einstein and his influence as the kristallnacht of science? Because he is! http://phys.org/n...ues.html
Pejico
May 14, 2014
This comment has been removed by a moderator.
Bonusje
1 / 5 (1) May 14, 2014
You do not know what it is about is it?