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Big Bang's Smoking Gun Found
astroengine writes "For the first time, scientists have found direct evidence of the expansion of the universe, a previously theoretical event that took place a fraction of a second after the Big Bang explosion nearly 14 billion years ago. The clue is encoded in the primordial cosmic microwave background radiation that continues to spread through space to this day. Scientists found and measured a key polarization, or orientation, of the microwaves caused by gravitational waves, which are miniature ripples in the fabric of space. Gravitational waves, proposed by Albert Einstein's General Theory of Relativity nearly 100 years ago but never before proven, are believed to have originated in the Big Bang explosion and then been amplified by the universe's inflation. 'Detecting this signal is one of the most important goals in cosmology today,' lead researcher John Kovac, with the Harvard-Smithsonian Center for Astrophysics, said in a statement."
Pretty damn cool.
My hat's off too all the hard-working, dedicated cosmetologists that made this possible.
A direct detection of a gravitational wave moving the mirrors of a large scale interferometer is up next. In the next few years, Advanced LIGO (US), Advanced Virgo (Italy) and KAGRA (Japan) will come online with the hope of directly detecting gravitational waves from sources such as supernovae and coalescing binary star systems. With this kind of network, it will then be possible to coordinate both electromagnetic and gravitational searches of our sky. This is useful for many reasons, one of which is that it lets us listen to the sound of black holes colliding where no light escapes.
Exciting times!
Einstein's theories continue to astound.
We already have plenty of direct evidence for the expansion of the universe. See redshifting of galaxies etc.
This announcement is about inflation - a particular period of rapid expansion immediately after the big bang.
There are three problems in cosmology that inflation solves: flatness: the universe is very close to its critical density, the horizon problem: the universe looks like it is in thermal equilibrium for no good reason, and absence of magnetic monopoles.
Note that this the second indirect evidence for the existence of gravitational waves, the first one was the orbital decay of a binary system that included a pulsar, discovered by Hulse and Taylor (Nobel Prize 1993). Today's result, if confirmed, seems pretty spectacular, and might be rewarded with a second Nobel Prize. For a first direct detection of gravitational waves, we have to wait for first detections by LIGO, Virgo and eLISA.
karma police: arrest this man, he talks in maths; he buzzes like a fridge, he's like a detuned radio. [radiohead]
Some interesting perspective from Matt Strassler, who's a particle physicist at Harvard.
He points out that this is still an *indirect* observation of gravitational waves (and not the first one) and that the results look sensibly in line with some predictions from inflation. And that while this is a tremendous experiment, it's not any kind of "smoking gun", and we really need to wait for replication to get properly excited.
All opinions expressed herein are not my own; I haven't had free will since last year when aliens ate my brain.
I think you have it wrong. You see, these creationists...they have a book which describes exactly how the world was created. It is called the Bible and it states pretty clearly how it happened. The problem here is that this so called "evidence" contradicts the very strong evidence they have...namely, their book.
Since it contradicts their book by claiming to take billions of years, it must (by very definition) be wrong. So what you really have is the Big bang is a bad interpretation of the natural world.
Now excuse my while I go wash my hands for typing that.
"I opened my eyes, and everything went dark again"
Gravitational waves are a prediction of general relativity and not related to gravitons (assuming that's what you meant) that are theorized to be the carrier of gravity in quantum gravity theories.
"Give me six lines of C++ code written by the most competent programmer, and I will find enough in there to hang him."
I feel them after every Thanksgiving meal.
Incorrect. Or, rather, been shown to be false by the evidence. And it was such a damn elegant model, too. Bravo to the team of researchers who've been working a decade on this satellite and these observations. I believe Neil and another scientist had a small bet about this, so he's also out of pocket a few dollars. Now we just have to hypothesise new ideas that will eliminate the many kludgy math bits out of Big Bang model. This news, and 120 more BlackBerry jobs lost today, means a sad day here in Waterloo (at the Perimeter Institute).
DaveyJJ
Perhaps if the Bible said '7 units of time' then there wouldn't be such a big emotional fuss over such a meaningless argument.
Technically, you're there, since the "first inch of expansion" contains the entire universe... literally.
This was the old news...
Basically sifting through information gathered from older CMB detectors, they discovered a statistical B-mode in the data that could have come from gravitational wave that occurred during inflation, but the data was really too noisy to be sure.
The new news is they used a new detectors which are capable of making cleaner measurements to convince themselves that the detected B-mode was unlikely to come from gravitational lensing after the big-bang. The current evidence apparently is consistent with the B-mode coming from a gravitational waves that are predicted to occur during the inflationary period of the universe.
Except your quote says exactly nothing of any use about what happened.
Did you hear that? That was the sound of millions of religious zealots pressing their palms harder against their ears and screaming LA LA LA even louder.
Remarkably, the oldest baryons in the* universe are in your head.
* From your reference frame. And only by a nanosecond or so.
The word typically translated "day" or "days" in Genesis is originally "Yowm" (root meaning "hot"). Strong's translates this variously as "period"—it's a very general term that I usually read as "era".
My limited understanding is that most of Jesus' contemporaries believed in an ancient universe. It was Ussher's bestseller that, ahem, fixed that problem.
Concordance here.
Ingenious inventions here.
Well, it does say about commanding their hosts. Physics has nothing to say about whether or not the universe had their hosts commanded during inflation, so this could be a valuable addition to our knowledge.
You're a temporary arrangement of matter sliding towards oblivion in a cold, uncaring universe
I met a guy from Sri Lanka once who had the best comment yet on "Prayer in schools":
"I am perfectly ok with prayer in schools, and I would encourage it but it seems a bit impractical if they don't already have an altar to catch the blood."
"I opened my eyes, and everything went dark again"
I don't know why you need to go arguing about all these fancy foreign words; if English was good enough for Jesus then it should be good enough for us to understand his teachings. You think if he wanted us using Hebrew words, he would have written the bible in it.
"I opened my eyes, and everything went dark again"
Well, Catholic schools (at least the one I went to) regularly teach evolution in their biology classes, amongst other things. They are hardly the same groups that push this anti-science BS (anymore), shit they even appologized to Galileo (after 400 years.... so they are....slow...)
While I have plenty I am happy to lambast the Catholics over; I have to hand it to them....they don't really push the creationism as we have come to know and despise. In fact, while you may find lay Catholics with all manner of beliefs, including young earth creationists and the like.... they Clergy tend to be a bit more level headed on these things and will often even say, flat out, the Bible is a book of allegorical stories and not a history book.
For example, as much as I dislike the man, Pope John Paul II did say:
"Today, almost half a century after publication of the encyclical, new knowledge has led to the recognition of the theory of evolution as more than a hypothesis. It is indeed remarkable that this theory has been progressively accepted by researchers, following a series of discoveries in various fields of knowledge. The convergence, neither sought nor fabricated, of the results of work that was conducted independently is in itself a significant argument in favor of the theory. "
That said, I did go to a Catholic High school, and there was a teacher told he was going to hell for teaching evolution.... he was told that by a student; not a priest, a brother, or anyone else in the clergy... a teenage student.
"I opened my eyes, and everything went dark again"
"First of all, how is it that all stars moving apart from each other rapidly is not "first direct evidence" of the universe's expansion?"
Because it isn't. The first direct evidence of the universe's expansion is typically accredited to Hubble in the 1920s and was very firmly established a good couple of generations back. Don't believe all you read in /. summaries...
"And secondly, how could the expansion of the universe amplify gravitational waves? Space stretching would thin out the waves because they would be expressed over a wider area."
Yes, it does indeed do so.
What this summary missed is that the universe was both extraordinarily small *and* undergoing inflation at the time. That's significant, because inflation was driven (in the theory) by the inflaton, a quantum field, and the size of the universe implied that the matter content was governed by (semi-classical) quantum theory -- ie quantum field theory on a curved but classical spacetime. Even earlier, it would be described by quantum gravity and we don't know what would happen.
Anyway, if you start looking at quantum fluctuations of a field such as the inflaton acting in something close to "slow-roll" (necessary for simple models to actually get out an inflation -- you need a field close to frozen in its potential so that it mimics a cosmological constant) then you get out an impressive array of density and metric perturbations. The density (and "scalar" metric) perturbations are what lead to the entire observable structure in the universe. Far smaller -- but, according to the results today, not *that* much smaller with an amplitude as large as 20% of the scalar -- are gravitational waves coming out. Entertainingly, even though you get out density and gravitational waves, you get basically negligible vorticity.
The results today are the first direct signal of inflation -- competing theories can produce the density perturbations and, just as importantly, their power spectrum, but frequently predict unobservably small gravitational radiation.
I would advise caution on these results since they rely on a remarkable "tilt" to the scalar power spectrum, which Bicep2 introduced to resolve a strong tension with Planck but which may (or may not) itself be in tension with Planck. That's going to be the first thing attacked -- in an investigative sense of the word, not an aggressive one -- by the community.
Who do you think predicted the gravitational radiation in the first place? There's a reason we've been wanting to find them since the 1990s and it's not that observational cosmologists were arguing with theoreticians that they were definitely there.
Tit.
"A viable alternate theory is that light gives up some energy while traveling extremely long distances, which shows up as red-shift. Where does the energy go? It could be the source of energy for the CMBR. It could go somewhere else. In any case, as a theory, it explains the red-shift just as well as expansion."
Excellent! Now repeat the rest of the predictions of the Lambda CDM model. Ah, no, you'll have trouble with that one.
"Another viable alternate theory is that the absorption/emission spectra of atoms differs with space/time. Perhaps atoms farther away or longer ago created and absorbed light at lower frequencies, this making older light appear red-shifted by current frequency comparisons. This theory is even harder to test, but just as good at explaining the observations. "
Even better! Now repeat the rest of the predictions of the Lambda CDM model. I think you'll have problems with that one, too.
Actually, I'll give you a bye -- all I want to see is the position of the first peak on the CMB *and* the wavelength of the oscillations in the large-scale structure, with one predicted consistently from the other. Once you've done that, if you can further get out supernovae 1a redshift/distance plots I'll give you extra credit, but since the progentiors aren't fully understood I'll give you a bye on that one, too.
See, the word "viable" has certain caveats. It has to satisfy the observations it's been built to explain *at least* as well as the theory it's replacing. Second, it has to -- self-consistently -- predict further observations that fit *at least* as well as the theory it's replacing. I'm no fan of Lambda CDM but its successes should convince anyone who's actually looked seriously at them that there's something close to reality there, even if ultimately it's a phenomenology close to reality (which it is; I can prove it's phenomenology -- rigorously -- but I can't demonstrate how wrong it actually is, and neither can anyone else at present, but I can at least assert that up until very recent times it's so close as to be indistinguishable and no that I fit all observations, and even very recently it's exceedingly good).
"if I'm allowed to make stuff up whenever I want to make my theory fit the model, I can do at least as well as the Lambda CDM"
Go ahead - you're more than welcome to. Empty assertions don't show much but new cosmological models are welcomed. *I* welcome them, anyway; I've never liked Lambda CDM much and it's obviously a phenomenological model. But they have to be predictive, and founded on firm principles.
I didn't actually want to suggest you're an idiot because I think it's apparent you're not, but this type of post at the same time implies that *cosmologists* are idiots and brainwashed into a model that doesn't really make much sense. And in some cases that's actually true -- there are more and more cosmologists trained into cosmology rather than general relativity and it's a bit dangerous -- but on the whole I don't think many people *like* LCDM. There are too many unanswered questions in it, and everyone is looking to answer those. Just some people work more tightly within its framework than others.
"is there a point where you would ever consider reexamining the questions of the assumptions? Why haven't we reached that point yet?"
Oh, don't misunderstand me -- I *constantly* question and re-examine the assumptions. At some point, if you're genuinely interested, flip back through my posts on Slashdot; I've made my position I think fairly clearly. Boiling it down and putting it in bullet form it goes something like this:
* The "big bang theory", and Lambda CDM in particular, is an astonishingly successful theory, particularly when attached to an inflationary period in the early universe or something that mimics its observational results closely
* The successes of Lambda CDM -- such as the predicted abundances from Big Bang nucleosynthesis, the *prediction* of the angular power spectra of the CMB (temperature auto-correlation, temperature/E mode cross correlation, E mode polarisation auto-correlation and now the B mode polarisation auto-correlation) from a simple early primordial power spectrum, the direct mapping between the wavelength of the sound horizon at last scattering as seen on the CMB and that same wavelength imprinted on large-scale structure and *observed* as the baryon acoustic oscillations, and their ilk -- are far too numerous and significant to be ignored.
* Any alternative absolutely has to preserve these, and they're all extremely sensitive
* Lambda CDM is wrong. It is dead wrong. It is wrong in principle. It is questionable from a particle physics perspective, particularly where it comes to dark energy, but far more importantly, it cannot be justified with general relativity.
Lambda CDM rests on a few main assumptions:
* The universe is on average isotropic around the Earth. OK, fine, we can't argue that; the CMB is proof enough.
* Since the Earth is nowhere special, the universe is on average isotropic around every point: homogeneous. Well, this is debatable since the Earth *is* in a particular position, but on the whole this is probably at least approximately true.
* Gravity is best described on large scales (ie > mm) by a metric theory. This is currently practically unquestionable; metric-based theories of gravity are vastly more succesful than any alternative.
* Gravity is described by general relativity. OK, now we're entering questionable territory but GR remains our best example of a metric-based theory and is yet to be seriously challenged (though there are many, myself among them, who point out that the appearance of dark matter on galactic scales, and the addition of dark energy on cosmological scales, may very well imply that actually we cannot apply gravity on such scales or else that it simply doesn't act this way on large scales)
* GR can be applied directly on large scales. This is extraordinarily shaky. Actually, it's unjustifiable. We've got two main objections here: firstly, there is no reason to assume that gravity actually obeys GR on large s
It's a question of how many different facts and observations each thing you assume can explain. If you, with a small number of assumptions, can explain a huge amount of data with good precision, that is a good and impressive. If that same number of assumptions, the same theory also can make predictions that survive comparison with new data, the theory is even better. By both these standards, Lambda CDM is a very good theory. As always it builds on some assumptions, but the amount of things it explains and the fact that new data (like the things announced today) fits well with it without any new additions or tweaks makes it a very good theory. You are welcome to try and do better, but I suspect you will have a lot of trouble making it work, and if you have to add special clauses to explain every bit of data, well, that just isn't impressive and your theory will be clearly worse than Lambda CDM. Also, making up stuff without messing up other parts of the theory isn't so very easy. If you add dark matter to fix some observations, you still have to make sure that it doesn't screw up some other prediction. When dealing with a mathematical theory, its actually quite rigid, as long as you don't do extremely unnatural things. Which the current model of inflation really doesn't do. Dark matter is just some stable electrically neutral particle, there isn't anything too mystical about that (we already know of some such particles actually, neutrinos). And dark energy was natural enough for Einstein to invent it back in 1915. I feel like the name "dark" bears a bit of negative/mystical connotations, leading people to question it way more than if it instead was called "neutral matter" or something less "scary".
Thank you for sharing your perspective like a gentleman. I respect that.
I think the core of our disagreement is with your expectation that all the things explained by LCDM must be explained by other theories. I believe it's perfectly fine for the answer to be that some things aren't connected. If we no longer assume we know the age of the universe, then predictions of element ratios no longer need to agree with observations of CMB, which may be totally disconnected from galaxy supercluster clumpiness. If red shift is seen to have some cause other than just expansion, then no unified theory has to predict how the universe got from a near-singularity to the observed state. Once you take a fixed finite timeline out of the picture, there can be different causes for different phenomena.
-Jaborandy
(Last post from me on this thread.)
This is the first direct evidence for gravity waves, but another very clever indirect one earned a Nobel Price in 1993.