Cosmic Inflation and Gravity Waves

[neufer]

It’s the most exciting discovery in cosmology for 25 years,
said theoretical physicist Lawrence Krauss of Arizona State University

To me that sounds a bit strange. To me as a complete amateur, the discovery of gravitational waves is a fantastic, brilliant triumph of technology and human perseverance and a wonderful step towards a "complete confirmation" of the Big Bang and the epoch of inflation. That's what makes this discovery so thrilling and so, well, huge.

The discovery of gravitational waves already came with the Hulse–Taylor binary pulsar.

This was:

• 1) a strong confirmation for inflation: http://asterisk.apod.com/viewtopic.php? ... 40#p222300
  2) the discovery of gravitons: http://asterisk.apod.com/viewtopic.php? ... 50#p222448

And anyway, if gravitational waves are the most exciting discovery in 25 years, then what was the exciting cosmological discovery that was made 25 years ago, in 1989?

A strong confirmation for the Big Bang from COBE:

Timeline of Observations of the CMB

1990 FIRAS on COBE measures the black body form of the CMB spectrum with exquisite precision.

Confirmational discoveries are generally somewhat more important
than surprise discoveries (such as that of the expansion of the universe).

[MargaritaMc]

A Polarizing Discovery About the Big Bang!

From minutephysics

Click to play embedded YouTube video.

Big Bang breakthrough explained with towel and apple


New Scientist

Uploaded on 19 Mar 2014
Full story: http://www.newscientist.com/article/dn25254

Need a giant IQ to understand the announcement about gravitational waves? Nonsense. Our video explains the basics using nothing but everyday objects

Click to play embedded YouTube video.

[MargaritaMc]

Another video, this time from the BBC. About twelve minutes long. The discussion with Professor Pryke at the end was especially interesting, I found.

Big bang scientist on a groundbreaking discovery

BBC Newsnight

Uploaded on 17 Mar 2014

Jeremy Paxman announces "this really is news": American scientists believe they've discovered what happened a fraction of a second after the Big Bang several billion years ago.

Chris Lintott of 'The Sky at Night' reports for Newsnight. Professor Clement Pryke, one of the scientists behind the discovery, discusses the findings with Maggie Aderin-Pocock and Hiranya Peiris.

Click to play embedded YouTube video.

[geckzilla]

A Polarizing Discovery About the Big Bang!

From minutephysics

Click to play embedded YouTube video.

You gotta love Henry for succeeding at explaining things like this so tersely.

[MargaritaMc]

You gotta love Henry for succeeding at explaining things like this so tersely.

I love Minute Physics And Vihart

[MargaritaMc]

NATURE: Gravitational-wave finding causes 'spring cleaning' in physics

Big Bang findings would strengthen case for multiverse and all but rule out a 'cyclic Universe'.

Ron Cowen
21 March 2014
...
“There’s a great spring cleaning, with almost everything ruled out,” says Max Tegmark, a cosmologist at the Massachusetts Institute of Technology (MIT) in Cambridge. “This is really shaking up not just the experimental field but the theoretical world.”

The BICEP2 data would eliminate about 90% of inflationary models, Andrei Linde, a cosmologist at Stanford University in California, told a packed auditorium at MIT the day after the BICEP2 announcement ... Many of those models do not produce gravitational waves at detectable levels, said Linde, who is one of the founders of inflation theory. ...

[geckzilla]

Planck took a cosmic dump of dust on this one today. In short, Planck sees the same signal BICEP2 saw but explains it with dust. As usual, astronomers will keep looking into it to make sure but it looks grim at the moment for the gravitational waves.

arXiv pre-print
http://arxiv.org/abs/1409.5738

Sean Carrol comments
http://www.preposterousuniverse.com/blo ... nal-waves/

Article by Natalie Wolchover, longer, has a few pictures
http://www.simonsfoundation.org/quanta/ ... anck-says/

[MargaritaMc]

Thank you for posting those articles, geck. I'd seen the arxiv preprint but needed (a great deal of help) in understanding its relevance to the BICEP2 work.

M

PS. These are from my notes, to fill in the story between the posts on this thread in March and now:

3/6/2014 http://www.nature.com/news/big-bang-blu ... E-20140605
Big Bang blunder bursts the multiverse bubble
Premature hype over gravitational waves highlights gaping holes in models for the origins and evolution of the Universe, argues Paul Steinhardt.

22/06/2014
• http://www.newscientist.com/article/dn2 ... 6cWzYxwb5B

• http://www.newscientist.com/article/mg2 ... 6cd2Ixwb5A interview with Andrei Linde.

[Chris Peterson]

Planck took a cosmic dump of dust on this one today. In short, Planck sees the same signal BICEP2 saw but explains it with dust. As usual, astronomers will keep looking into it to make sure but it looks grim at the moment for the gravitational waves.

I don't see that at all. This hardly changes anything with respect to the theory around gravitational waves. It just argues that the BICEP2 data was misinterpreted. Much of the original skepticism surrounded the view that BICEP2 lacked the sensitivity to even detect the polarization signal if it were present. This new data bolsters that view much more than it suggests anything is wrong with our cosmological model.

[geckzilla]

Yes, I should have written that it looks grim for BICEP2's detection of them.

[bystander]

Planck took a cosmic dump of dust on this one today. In short, Planck sees the same signal BICEP2 saw but explains it with dust. As usual, astronomers will keep looking into it to make sure but it looks grim at the moment for the gravitational waves. ...

Gravitational Waves According to Planck
International School for Advanced Studies (SISSA) | 2014 Sep 22

[i]The figure shows the signal (unbroken black line) that the BICEP2 experiment had suggested as an explanation for its results, in terms of cosmological gravitational waves. The bands represent the Planck data on the intensity of Galactic dust as a contaminating signal. As can be seen, the contaminating signal observed by Planck can explain, within instrumental uncertainty, the entire BICEP2 observation.[/i]

---

Data from the ESA Satellite Measure the BICEP2 Observation

Scientists of the Planck collaboration, and in particular the Trieste team, have conducted a series of in-depth checks on the discovery recently publicised by the BICEP2 project (the Antarctic observatory), which announced last spring that it had detected some direct effects of gravitational waves on cosmic microwave background radiation, a (potentially) groundbreaking discovery in the field of cosmology. Many scientists raised doubts: could the signal observed be the result of contaminants? The BICEP2 scientists exclude this possibility, but analysis of the Planck satellite data demonstrates that the effect of contaminating sources, such as gases from our Galaxy, cannot be ruled out. ...

The strength of Planck -- which provides a coarser-grained picture of the sky compared to BICEP2 -- is that it observes the universe at a very wide range of frequencies (nine bands from 30 to 857 GHz, as against the single frequency of 150 GHz used by BICEP2). And it is precisely this “multiple” image which enabled the Planck scientists to establish that the effect of a contaminant may indeed be at work. ...

Planck intermediate results. XXX. The angular power spectrum of polarized dust
emission at intermediate and high Galactic latitudes - Planck Collaboration

• arXiv.org > astro-ph > arXiv:1409.5738 > 19 Sep 2014

Edit: I had already prepared this post from a source in my e-mail today when I remembered I had seen something similar, so I moved it here and added the gecko's reference. It doesn't really add anything new to what she had already posted, just another source.

[MargaritaMc]

I thought this bit from the SSISA news release was interesting, and might add just a little bit to what we've read already:

International School of Advanced Studies (SISSA)

http://www.eurekalert.org/pub_releases/ ... 092214.php
...
The news is not all bad, however, and could instead prove "fruitful": "we have started a collaboration with BICEP2. We are directly comparing their data with the Planck data, in the same frequency, 150 GHz, and trying to exploit the image of the contaminants we reach with Planck at other frequencies", continues Baccigalupi.[ one of the authors of the study ] "This way, we hope to be able to give a definitive answer. In fact, we might find that it was indeed a contamination, but, given that we're optimists, we might even be able to exclude it with confidence. This way, Planck could give a crucial contribution to the discovery of evidence of gravitational waves from the Big Bang in cosmic background radiation. Such a discovery would open a completely new window onto unknown scenarios in the study of the primordial Universe and very-high-energy physics".

PS. I've just come across this news article in Nature via an email today: http://www.nature.com/news/full-galaxy- ... S-20140923

[MargaritaMc]

I came across this useful Sky and Telescope article too late to be able to edit it into the post I made above. There is no new information here, but it is a well written résumé.
http://www.skyandtelescope.com/astronom ... =246938601

[geckzilla]

Astrobites article by Zachary Slepian.
"Dust gets interesting" It does! Click:
http://astrobites.org/2014/10/09/dust-gets-interesting/

[MargaritaMc]

ESA Planck: Gravitational Waves Remain Illusive

Click to view full size image

Planck view of BICEP2 field

30 January 2015

Despite earlier reports of a possible detection, a joint analysis of data from ESA’s Planck satellite and the ground-based BICEP2 and Keck Array experiments has found no conclusive evidence of primordial gravitational waves.
...
The BICEP2 team had chosen a field where they believed dust emission would be low, and thus interpreted the signal as likely to be cosmological.

However, as soon as Planck’s maps of the polarised emission from Galactic dust were released, it was clear that this foreground contribution could be much higher than previously expected.

In fact, in September 2014, Planck revealed for the first time that the polarised emission from dust is significant over the entire sky, and comparable to the signal detected by BICEP2 even in the cleanest regions.

So, the Planck and BICEP2 teams joined forces, combining the satellite’s ability to deal with foregrounds using observations at several frequencies – including those where dust emission is strongest – with the greater sensitivity of the ground-based experiments over limited areas of the sky, thanks to their more recent, improved technology. By then, the full Keck Array data from 2012 and 2013 had also become available.

“This joint work has shown that the detection of primordial B-modes is no longer robust once the emission from Galactic dust is removed,” says Jean-Loup Puget, principal investigator of the HFI instrument on Planck at the Institut d’Astrophysique Spatiale in Orsay, France.

“So, unfortunately, we have not been able to confirm that the signal is an imprint of cosmic inflation.”

Click to view full size image

Planck view of Galactic dust

JPL: Gravitational Waves from Early Universe Remain Elusive

http://asterisk.apod.com/viewtopic.php?f=9&t=34394

M

[FloridaMike]

If this holds up, it's HUGE!!!

Ann

Cosmologically Complicating Dust

Click to play embedded YouTube video.