Showing posts with label big bang. Show all posts
Showing posts with label big bang. Show all posts

Monday, March 17, 2014

Further evidence for inflation from polarisation of gravitational waves


John Davison
1 hr · Christchurch, Dorset
I shall take my time to try and take this lot on board:
http://www.bbc.co.uk/news/science-environment-26605974
I said...
http://profmattstrassler.com/2014/03/17/bicep2-new-evidence-of-cosmic-inflation/ - this guy explains stuff well normally. Under the Main data Strassler says "the leftmost 3 or 4 points are the ones that give evidence for B-mode polarization, and therefore possibly for gravitational waves at early times, and therefore, possibly, for cosmic inflation preceding the Hot Big Bang!"

original BICEP2 paper published 17/3/14: http://bicepkeck.org/

http://www.cfa.harvard.edu/CMB/keckarray/science.html science of BICEP project "We are interested in answering some of the biggest and most exciting questions about the nature of the Universe. What was the Universe like at the beginning of time? How did the Universe come to be the way it is today? Through precision measurements of the Cosmic Microwave Background (CMB), we directly explore the Universe as it was shortly after the Big Bang, and hope to solve some of the mysteries that exist in Cosmology today."

looking easier to understand http://profmattstrassler.com/2014/03/17/a-primer-on-todays-events/

John Davison Thanks for the links Chris, I have to go through a whole OCD routine to acquire the right pace and mental frame for this stuff. You know, fresh pot of tea, rearrange the desktop, check the cat etc etc your links very helpful.


Strassler warns...

"Be More Cautious than the Media

As always, I have to caution you that although I’m fairly impressed, and reasonably optimistic about this measurement, it is a measurement by only one experiment.  Until this measurement/discovery is confirmed by another experiment, you should consider it provisional.  Although this is too large a signal to be likely to be due to a pure statistical fluke, it could still be due to a mistake or problem, or due to something other than gravitational waves from inflation.  The history of science is littered with examples; remember the 2011 measurement by OPERA that showed neutrinos moving faster than the speed of light was far too large to be a statistical fluke.  Fortunately there will be other experiments coming and so we’ll have a chance for various experiments to either agree or disagree with each other in the very near future. " http://profmattstrassler.com/2014/03/17/bicep2-new-evidence-of-cosmic-inflation/

Stasslers finishes http://profmattstrassler.com/2014/03/17/bicep2-new-evidence-of-cosmic-inflation/ with...

"What It Means if it’s True

If this measurement is correct, and if indeed it reflects gravitational waves from inflation in the most conventional way, then it would tell us that inflation occurred with a dark energy per unit volume (i.e. dark energy density) that is comparable to the energy scales associated for decades with the energy and distance scale at which all the known non-gravitational forces would naively have about the same strength — the so-called “unification of coupling constants”, sometimes extended to “grand unification” in which the various forces actually turn out to be manifestations of just a single force.  This would be very remarkable,  though not necessarily evidence for unification.  There are other ways to get the same scale, which is about 100 times lower in energy (100,000,000 times lower in energy per unit volume)  than the scale of quantum gravity (the Planck scale, which, roughly, tells you the energy density required to make the smallest possible black hole.)"

 http://www.cfa.harvard.edu/CMB/keckarray/science.html says...
"The CMB and InflationInflation is a theory which provides a neat solution to these "problems." According to the theory of Inflation, the Universe underwent a violent and rapid expansion at only 10^-35 seconds after the Big Bang, making the horizon size much larger, and allowing the space to become flat. Confirmation of Inflation would be an amazing feat in observational Cosmology. Inflation during the first moments of time produced a Cosmic Gravitational-Wave Background (CGB), which in turn imprinted a faint but unique signature in the polarization of the CMB. Since gravitational waves are by nature tensor fluctuations, the polarization signature that the CGB stamps onto the CMB has a curl component (called "B-mode" polarization). In contrast, scalar density fluctuations at the surface of last scattering only contribute a curl-free (or "E-mode") polarization component to the CMB which was first detected by the DASI experiment at the South Pole.

BICEP1, BICEP2, Keck Array, and BICEP3
Observing from the South Pole, this series of experiments aims to discover signatures of Inflation by actually detecting the CGB via its weak imprint as the unique B-mode polarization signature of the CMB, directly probing the Universe at an earlier time than ever before. Each generation represents a large increase in sensitivity to B-mode polarization. BICEP1 observed from 2006-2008 with 98 detectors, BICEP2 began observing in the beginning of 2010 with 512 detectors, and the first three of five Keck Array telescopes began observing in the beginning of 2011, each with 512 detectors. The final two Keck Array receivers were deployed during the summer season of 2012. BICEP3, with a total of 2,560 detectors, will begin observing in 2015."

History of the Universe: http://profmattstrassler.com/articles-and-posts/relativity-space-astronomy-and-cosmology/history-of-the-universe/
Strassler says 
"Today, we live roughly 13.7 billion (13,700,000,000) years after the start of the Hot Big Bang. Notice I don’t say that “the universe is 13.7 billion years old” or that “the beginning of the universe was 13.7 billion years ago”… we don’t know that. What we do know is just that the Hot Big Bang began 13.7 billion years ago — but we don’t know if that moment was close to the beginning of the universe as a whole, or anything about what that beginning might have been like, if there even was a beginning."


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Wednesday, December 29, 2010

Evidence for many Big Bangs?


26 December 2010 Last updated at 01:49

Bangs big and small in cosmic origins debate

source: http://www.bbc.co.uk/news/science-environment-11960756
By Jason PalmerScience and technology reporter, BBC News
Planck all-sky CMB image (Esa/HFI/LFI consortium)

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There's an idea in the area of physics known as quantum mechanics that suggests one can't measure a phenomenon without influencing the result.
It turns out that sometimes this same "observer effect" crops up in science journalism.
The story goes that, right now, there is a quiet debate happening that could have implications for how the Universe as we know it came to be - and what came before.
And the debate is being driven in part by the fact that news outlets including BBC News took a small peek into the machine of modern-day astrophysics.
It started in a fairly pedestrian way: I spotted a paper authored by someone with a familiar name, outlining analyses of what is known as the cosmic microwave background, or CMB.
Professor Sir Roger Penrose, along with his colleague Vahe Gurzadyan, had crunched through the publicly-available data on this ever-so-slightly jumbled glow of light that permeates the whole of the cosmos.
They found neat, circular rings of order in the CMB, a feature which would support a theory of Professor Penrose's: that the Big Bang is just the latest in an endless cycle, rather than a beginning per se.
"Rings" in WMAP microwave background data (VG Gurzadyan/R Penrose)The initial paper suggested these rings were echoes from before the Big Bang
As is common among cosmologists, the researchers published the idea on Arxiv.org, a repository for scientific papers before they go through the publishing process -where I found the manuscript and wrote a story on it, among other news outlets.
Three weeks later, two papers were posted to the Arxiv site refuting Professor Penrose's hypothesis: one by Hans Kristian Eriksen and Ingunn Wehus at the University of Oslo and another by Douglas Scott, Jim Zibin, and Adam Moss from the University of British Columbia.
Just two days later, a third refutation by Amir Hajian of the University of Toronto appeared.
It is rare that science works in this way; rarer still that it works at this speed. And there is some indication it's going this way in part because the BBC and others shed light on the initial paper.
In any case, the process is a remarkable, almost-but-not-quite public airing - kind of like a high-speed film of how scientific discourse can go on - with footnotes.
Anomalous
There are a number of factors driving this unusual debate. Perhaps the most obvious is the "celebrity science" factor.
"What's going on is that out of many outrageous claims made in cosmology each year, one was singled out recently for a huge amount of attention," Douglas Scott told BBC News.
"That would not have been the case had it come from someone without the reputation of Sir Roger."
It should also be said that Professor Penrose is championing a theory that, if correct, would completely upend the "inflationary cosmology" that is the current, widely-accepted best guess as to the Universe's origins.

“Start Quote

As far as the public is concerned, in a situation like [this one] the publicity may happen too fast to get out the news that there were big errors with the work; once the errors are found, the story has died down and the media have moved on”
Jim ZibinUniversity of British Columbia
Or, as Hans Eriksen put it: "The story contained a rather explosive mix of pre-Big Bang physics, black holes and Roger Penrose - any science journalist has got to love that."
And so we did. But Dr Eriksen hinted also at another factor surrounding the story - that the public nature of the data made the analysis easy to repeat - and refute.
That is, the current best-available data on the CMB are free to download; for now, that comes from the Wilkinson Microwave Anisotropy Probe, or Wmap.
Jo Dunkley, a University of Oxford astrophysicist and part of the Wmap team, explained that the hunt for "anomalies" like that posited by Professor Penrose is a common pursuit.
"That's a whole industry in our field, to look for unusual things in the maps," Dr Dunkley tells me.
"In the map of the sky, you can see an 's' and an 'h' if you look carefully. People have joked that it's Stephen Hawking's signature on the sky, but obviously we don't think that's significant.
"The nice thing about Penrose's theory is that it's a theory that you then go and test; that's exactly what we should be doing."
She's right. While all of this is going on, another paper is posted on the Arxiv that purports to see "bruises" of other universes in the CMB. That, too, should be tested for significance - perhaps before it gets media attention.
Error bars
The standard first test is to plug the new idea into simulations of the sky; you create a model on the basis of everything that is known and the result should replicate what observations bear out in the real CMB data.
It is here that the authors of the three rebuttal manuscripts suggest that Gurzadyan and Penrose have got it wrong. They say the original paper shows nothing more than what your common-or-garden inflationary cosmologist would have predicted on the basis of existing theory.
To prove the point, Douglas Scott and colleagues showed that a hunt for triangles in the CMB was statistically as successful as that for the circles that support Professor Penrose's theory.
After that, but before the third paper was published, Penrose and Gurzadyan had posted their riposte; it is clear that the subtleties of the argument are still being discussed, principally through the medium of the Arxiv site.
For some corners of science, this "preprint" culture is faster than the traditional refereed journal approach, in which results are sent to journals, who choose appropriate but anonymous experts to sign off the veracity or merit of the work.
Planck telescope first images (SPL)The Planck telescope will soon be providing significantly more detailed data on the CMB
But preprint servers are to that process as YouTube is to Cannes: you can find more, faster, but you can't know much about the quality of what you'll see.
"The new technology raises new problems but also provides the means to resolve them quickly," Jim Zibin told BBC News. "In a sense... the old refereeing system is not fast enough to respond, and a new, informal form of refereeing appears to fill the void.
Preprints and these debates can be seen as a workshop, then - but Amir Hajian says it is important to have a home for the finished product.
"The debates finally end - that is the nature of science," he told BBC News.
"Unknowns will be knowns sooner or later; what is important is to have trusted refereed journals to publish the final polished version of each work."
In the interim, Dr Zibin hinted that media interest kicks off the "observer effect" in the delicate experimental setup.
"As far as the experts are concerned, incorrect work will either be corrected via Arxiv comments, the standard review process, or more slowly over many years and many papers, or will simply go unnoticed and forgotten.
"But as far as the public is concerned, in a situation like [this one] the publicity may happen too fast to get out the news that there were big errors with the work. Once the errors are found, the story has died down and the media have moved on."

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Before the Big Bang - evidence for cyclical universe - Roger Penrose

reposted from: http://www.bbc.co.uk/news/science-environment-11837869


27 November 2010 Last updated at 10:30

Cosmos may show echoes of events before Big Bang

By Jason PalmerScience and technology reporter, BBC News
"Rings" in WMAP microwave background data (VG Gurzadyan/R Penrose)The variation in the background shifts sharply within the rings

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Evidence of events that happened before the Big Bang can be seen in the glow of microwave radiation that fills the Universe, scientists have asserted.
Renowned cosmologist Roger Penrose said that analysis of this cosmic microwave background showed echoes of previous Big Bang-like events.
The events appear as "rings" around galaxy clusters in which the variation in the background is unusually low.
The unpublished research has been posted on the Arxiv website.
The ideas within it support a theory developed by Professor Penrose - knighted in 1994 for his services to science - that upends the widely-held "inflationary theory".
That theory holds that the Universe was shaped by an unthinkably large and fast expansion from a single point.
Much of high-energy physics research aims to elucidate how the laws of nature evolved during the fleeting first instants of the Universe's being.
"I was never in favour of it, even from the start," said Professor Penrose.
"But if you're not accepting inflation, you've got to have something else which does what inflation does," he explained to BBC News.
"In the scheme that I'm proposing, you have an exponential expansion but it's not in our aeon - I use the term to describe [the period] from our Big Bang until the remote future.
"I claim that this aeon is one of a succession of such things, where the remote future of the previous aeons somehow becomes the Big Bang of our aeon."
This "conformal cyclic cosmology" (CCC) that Professor Penrose advocates allows that the laws of nature may evolve with time, but precludes the need to institute a theoretical beginning to the Universe.
Supermassive find
Professor Penrose, of Oxford University, and his colleague Vahe Gurzadyan of Yerevan State University in Armenia, have now found what they believe is evidence of events that predate the Big Bang, and that support CCC.
They looked at data from vast surveys of the cosmic microwave background - the constant, nearly uniform low-temperature glow that fills the Universe we see.
They surveyed nearly 11,000 locations, looking for directions in the sky where, at some point in the past, vast galaxies circling one another may have collided.
The supermassive black holes at their centres would have merged, turning some of their mass into tremendous bursts of energy.
WMAP dataThe microwave background has, on average, only minor variations
The CCC theory holds that the same object may have undergone the same processes more than once in history, and each would have sent a "shockwave" of energy propagating outward.
The search turned up 12 candidates that showed concentric circles consistent with the idea - some with as many as five rings, representing five massive events coming from the same object through the course of history.
The suggestion is that the rings - representing unexpected order in a vast sky of disorder - represent pre-Big Bang events, toward the end of the last "aeon".
"Inflation [theory] is supposed to have ironed all of these irregularities out," said Professor Penrose.
"How do you suddenly get something that is making these whacking big explosions just before inflation turns off? To my way of thinking that's pretty hard to make sense of."
Shaun Cole of the University of Durham's computational cosmology group, called the research "impressive".
"It's a revolutionary theory and here there appears to be some data that supports it," he told BBC News.
"In the standard Big Bang model, there's nothing cyclic; it has a beginning and it has no end.
"The philosophical question that's sensible to ask is 'what came before the Big Bang?'; and what they're striving for here is to do away with that 'there's nothing before' answer by making it cyclical."
Professor Cole said he was surprised that the statistical variation in the microwave background data was the most obvious signature of what could be such a revolutionary idea, however.
"It's not clear from their theory that they have a complete model of the fluctuations, but is that the only thing that should be going on?
"There are other things that could be going on in the last part of the previous aeon; why don't they show even greater imprints?"
Professors Penrose and Cole both say that the idea should be shored up by further analyses of this type, in particular with data that will soon be available from the Planck telescope, designed to study the microwave background with unprecedented precision.
Planck data (Esa)Planck will provide a plethora of data that may prove or disprove the idea

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