Astronomers discover polarised ripples in the cosmic background radiation that could be caused by gravitational waves of the inflating universe.
Inflation was first proposed in the early 1980s to explain some aspects of Big Bang Theory that appeared to not quite add up, such as why deep space looks broadly the same on all sides of the sky. The contention was that a very rapid expansion early on could have smoothed out any unevenness.
But inflation came with a very specific prediction - that it would be associated with waves of gravitational energy, and that these ripples in the fabric of space would leave an indelible mark on the oldest light in the sky - the famous Cosmic Microwave Background.
The BICEP2 team says it has now identified that signal. Scientists call it B-mode polarisation. It is a characteristic twist in the directional properties of the CMB. Only the gravitational waves moving through the Universe in its inflationary phase could have produced such a marker. It is a true "smoking gun".
From here].
Hey, I heard it in the Swiss radio news!
As a junior particle physicist, Guth first developed the idea of cosmic inflation in 1979 at Cornell and gave his first seminar on the subject in January 1980. Moving on to Stanford University Guth formally proposed the idea of cosmic inflation in 1981, the idea that the nascent universe passed through a phase of exponential expansion that was driven by a positive vacuum energy density (negative vacuum pressure). The results of the WMAP mission in 2006 made the case for cosmic inflation very compelling. Measurements by the BICEP and Keck Array telescope give support to the idea of cosmic inflation, confirmation of which was given on March 17, 2014, with the findings of the B-mode polarization signature.
Bold by me.
Italics too: it shows the actuality of Wikipedia. People who love their disciplines seem to be pretty fast to update Wikipedia.
Astronomers discover polarised ripples in the cosmic background radiation that could be caused by gravitational waves of the inflating universe.
Inflation was first proposed in the early 1980s to explain some aspects of Big Bang Theory that appeared to not quite add up, such as why deep space looks broadly the same on all sides of the sky. The contention was that a very rapid expansion early on could have smoothed out any unevenness.
But inflation came with a very specific prediction - that it would be associated with waves of gravitational energy, and that these ripples in the fabric of space would leave an indelible mark on the oldest light in the sky - the famous Cosmic Microwave Background.
The BICEP2 team says it has now identified that signal. Scientists call it B-mode polarisation. It is a characteristic twist in the directional properties of the CMB. Only the gravitational waves moving through the Universe in its inflationary phase could have produced such a marker. It is a true "smoking gun".
From here].
Hey, I heard it in the Swiss radio news!
Amazing stuff, interesting image, thanks for sharing.
It makes me dizzy trying to comprehend that stuff.
Even the most basic, 'cosmic waves', when I think of waves I think of the rock dropping the pond, or noise moving out from something and then settling back to nothing... except for return-waves echoing back from something.
But in space the big bang and then, on a cosmic scale, there's nothing for these waves to bounce off of.
Or is it a different wave who's properties change but it stays localized.
Truly bizarre and beautiful.
In past earlier decades I have had periods where I really got into the history of turn of the century physics and the whole quantum revolution. And it's interesting for a non-specialist to read these reports and abstracts that are well over my head, but there were those basics that I did have some idea about, catch here and there.
Like the modern cell phone conversation where the connection drops out, or distorts horribly, etc. And when the conversation is done I'm stuck putting the pieces together best I can. But, it's fun and interesting, specially considering I've been spectator for 50 years, and all the evolution of ideas I've witness, even if I can only actually comprehend a small fraction of those scientific insights.
This is a perfect example of what’s “wrong” with science (and obviously I’m being sarcastic). Capitalism, Religion, Politics are spoiled selfish children who want it all, right now, give it to ME ME ME. Science is a patient group of adults who will take a little bit at a time, over the course of even 30+ years, and will work together to get it. And even then, they want to make sure it’s the real thing, versus C,R, and P who will be ok with a good fake as long as they can convince others it’s not a fake.
yea, and what does 'localized' mean on a cosmic scale :lol:
a point in the "fabric" of space ?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This is a perfect example of what's "wrong" with science (and obviously I'm being sarcastic). Capitalism, Religion, Politics are spoiled selfish children who want it all, right now, give it to ME ME ME. Science is a patient group of adults who will take a little bit at a time, over the course of even 30+ years, and will work together to get it. And even then, they want to make sure it's the real thing, versus C,R, and P who will be ok with a good fake as long as they can convince others it's not a fake.
So the CMB is polarised in a manner consistent with inflation having happened. Very good.
(Puts Devil’s Advocate hat on).
But … Could there be an alternative explanation? Or possibly several alternative explanations?
Has anyone looked for alternative explanations?
Or is this just one more example of confirmation bias?
And - more basic still - how accurate are these measurements?
Just a few heretical thoughts … nothing really (ducks down behind a chair).
TFS
TFS, scientists have been looking for alternative explanations for 30 years and found nothing that matches the new observations.
Darron, CMB polarisation has only recently been discovered, so I don't see that it makes much sense to say that scientists have been looking for alternative explanations for it for thirty years.
What cosmologists have been looking for for thirty years is evidence for inflation - which they now think they've found. No-one, to my knowledge, has seriously suggested any alternative to the current Big Bang + Inflation model, despite its glaring inconsistencies - not the least of them being the necessity for the universe to have expanded at greater than the velocity of light, post-inflation.
TFS
What makes you think the universe expanded faster than light post-inflation?
And cosmologists have been working on alternate theories to the Big Bang far longer than 30 years. No one has come up with a viable alternate theory. You know, one which would explain the observations better than the Big Bang Theory.
In every direction we look, we see galaxies that are, supposedly, up to 12 billion light years away from us.
But, of course, when we look at these galaxies we’re looking into the past; we’re seeing them, not as and where they “are” today, but as AND WHERE they were, 12 billion years ago.
Thus, 12 billion years ago, the universe was already AT MINIMUM a sphere of 12 billion light years radius.
But the universe is only 13.8 billion years old, by the most recent estimates; therefore, in less than two billion years, the universe expanded to AT A MINIMUM 12 billion light years radius.
i.e. much faster than the velocity of light.
And to say “space is curved” doesn’t help. Space is curved locally around centres of mass, but by the most reliable measurements, on the cosmic scale the universe is “flat” within 2%.
TFS
That is an epic logic fail. Other galaxies are 12 billion light years from us because the universe has been expanding in the intervening years. We are seeing those galaxies as they were 12 billion years ago, not where they were 12 billion years ago. Even though the expansion rate of the universe is accelerating it is nowhere near the speed of light and has not been since the Inflationary Period.
See How fast is the universe expanding?] on NASA’s site.
This presents a serious problem; if the universe had started with even slightly different temperatures in different areas, then there would simply be no way it could have evened itself out to a common temperature by this point in time.
Inflation as a possible solution:
The theory of cosmic inflation provides one solution to the problem (along with several others such as the flatness problem) by postulating a short 10^32 second period of exponential expansion (dubbed "inflation") in the first seconds of the history of the universe.
A recurrent criticism of inflation is that the invoked inflation field does not correspond to any known physical field, and that its potential energy curve seems to be an ad hoc contrivance to accommodate almost any data obtainable. Paul J. Steinhardt, one of the founding fathers of inflationary cosmology, has recently become one of its sharpest critics. He calls 'bad inflation' a period of accelerated expansion whose outcome conflicts with observations, and 'good inflation' one compatible with them: "Not only is bad inflation more likely than good inflation, but no inflation is more likely than either.... Roger Penrose considered all the possible configurations of the inflaton and gravitational fields. Some of these configurations lead to inflation ... Other configurations lead to a uniform, flat universe directly – without inflation. Obtaining a flat universe is unlikely overall. Penrose's shocking conclusion, though, was that obtaining a flat universe without inflation is much more likely than with inflation – by a factor of 10 to the googol (10 to the 100) power!"
Bold added by me.
Alternative to inflation:
The flatness and horizon problems are naturally solved in the Einstein-Cartan-Sciama-Kibble theory of gravity, without needing an exotic form of matter and introducing free parameters.This theory extends general relativity by removing a constraint of the symmetry of the affine connection and regarding its antisymmetric part, the torsion tensor, as a dynamical variable. The minimal coupling between torsion and Dirac spinors generates a spin-spin interaction that is significant in fermionic matter at extremely high densities. Such an interaction averts the unphysical Big Bang singularity, replacing it with a cusp-like bounce at a finite minimum scale factor, before which the Universe was contracting. The rapid expansion immediately after the Big Bounce explains why the present Universe at largest scales appears spatially flat, homogeneous and isotropic. As the density of the Universe decreases, the effects of torsion weaken and the Universe smoothly enters the radiation-dominated era.
Bold added by me.
The unphysical big bang singularity is highly problematic.
That is an epic logic fail. Other galaxies are 12 billion light years from us because the universe has been expanding in the intervening years. We are seeing those galaxies as they were 12 billion years ago, not where they were 12 billion years ago.
How do you figure we're not seeing them where they were 12 billion years ago? What you're saying sounds like post hoc rationalisation to me - more like theology than science. You're doing exactly what "pseudoscientists" are often accused of doing - beginning with the conclusion ("The Big Bang happened") and then cherrypicking the "evidence" to suit.
TFS
You're doing exactly what "pseudoscientists" are often accused of doing - beginning with the conclusion ("The Big Bang happened") and then cherrypicking the "evidence" to suit.
TFS
Except for all the evidence that shows the universe began with a hyper inflationary event. You're doing what crackpots do on any subject: ignoring the scientific evidence and consensus and manufacturing a controversy.
How do you figure we're not seeing them where they were 12 billion years ago? What you're saying sounds like post hoc rationalisation to me - more like theology than science. You're doing exactly what "pseudoscientists" are often accused of doing - beginning with the conclusion ("The Big Bang happened") and then cherrypicking the "evidence" to suit.
TFS,
Your arguing about the expansion of the universe, the big bang and inflation is a bit too simple. I cannot say that I could give a proper account of it, but at least I know what the cosmologists say about your questions.
The universe is not expanding in some empty space, it is space that is expanding itself. The velocity of light however is about its movement in space. There is a lot of evidence that the big bang happened, but there are problems left, the uniformity of space being one of them. Inflation is an ad hoc hypothesis to explain this uniformity (e.g. the existence of an inflationary field had to be postulated) but it would nicely explain a few features of our universe. Now, one of the predictions of inflation, about the polarisation of the cosmic background radiation, has been confirmed, so it made the theory of cosmic inflation stronger. The search for verification (or falsification) of the theory separates it definitely from pseudo science.
Just have a glance at the Wikipedia articles about the big bang and about cosmic inflation: there the empirical evidence is nicely summed up.
I’m going with the Big Bounce theory. Mainly because the history of cosmological discovery is replete with discoveries that make us seem smaller and smaller. The Big Bang theory purports that we have an inkling of how everything started. The Big Bounce, I take it, would mean that we are not even close to actually understanding how everything started. Since scientific discovery tends to show us how ignorant we were before the discovery, I go with the theory that is best in line with that. And besides, as related in Kkwan’s post :
“The flatness and horizon problems are naturally solved in the Einstein-Cartan-Sciama-Kibble theory of gravity, without needing an exotic form of matter and introducing free parameters.This theory extends general relativity by removing a constraint of the symmetry of the affine connection and regarding its antisymmetric part, the torsion tensor, as a dynamical variable. The minimal coupling between torsion and Dirac spinors generates a spin-spin interaction that is significant in fermionic matter at extremely high densities. Such an interaction averts the unphysical Big Bang singularity, replacing it with a cusp-like bounce at a finite minimum scale factor, before which the Universe was contracting. The rapid expansion immediately after the Big Bounce explains why the present Universe at largest scales appears spatially flat, homogeneous and isotropic. As the density of the Universe decreases, the effects of torsion weaken and the Universe smoothly enters the radiation-dominated era.”
So there.
It’s not illegal to discuss cosmology and theoretical physics at CFI of course. But if you’ve ever lurked in a physics/cosmology forum where the real deal folks discuss things, you quickly realize that our layman’s-speak is pretty much unusable for these types of discussions. We may think we’re saying something meaningful when we talk about the expansion of the universe, matter densities, and so on, but it only seems that way. I’ve even heard young professors of physics at top notch organizations interviewed about some of this stuff and their response was “got me, this is way beyond me”. So if it’s beyond THEM, then us layman might as well just go back to enjoying the pretty pictures on Cosmos. (Unless you’re young and smart and have a chance of lifting yourself educationally to that level.)