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The Big Bang's Last Great Prediction

samzenpus posted about 6 months ago | from the in-the-beginning dept.

Space 80

StartsWithABang (3485481) writes "Even with the add-ons of dark matter, dark energy and inflation, the Big Bang still thrives as the most successful scientific model of the Universe ever constructed. It not only accounting for phenomena like the abundance of the light elements, the cosmic microwave background, and the Universe's large-scale structure, but it's led to observable predictions about their details that have since been verified. But there's one thing the Big Bang has generically predicted that we haven't been able to test: a cosmic background of low-energy, relic neutrinos."

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Relic Hunter (5, Funny)

Anonymous Coward | about 6 months ago | (#47072639)

We must collect the low-energy neutrinos before the neo-Nazis find them!

Re:Relic Hunter (1)

dadelbunts (1727498) | about 6 months ago | (#47072723)

This made me fucking lol.

Re:Relic Hunter (-1)

Anonymous Coward | about 6 months ago | (#47072819)

I guess this whooshed a few folk with mod points...

And yet... (1)

Anonymous Coward | about 6 months ago | (#47072641)

The humble banana disproves this all.

Re:And yet... (0)

Anonymous Coward | about 6 months ago | (#47073705)

If that were true then why is it so humble?

only a blog post? (0)

Anonymous Coward | about 6 months ago | (#47072653)

As good as it is, I was expecting a bit more than a blog post.

Re:only a blog post? (5, Funny)

Anonymous Coward | about 6 months ago | (#47072659)

Bloggers are the new journalists in the hipster era, soon to be known as the Stupid Ages.

Theory as it stands is wrong (5, Interesting)

nemasu (1766860) | about 6 months ago | (#47072715)

I just found this out a couple weeks ago, and it blew my mind, the big bang theory actually does not explain things we can actually observe right now.
For instance, the Hercules–Corona Borealis Great Wall [wikipedia.org]

Re:Theory as it stands is wrong (0)

Anonymous Coward | about 6 months ago | (#47072761)

How does that contradict the Big Bang?

Re:Theory as it stands is wrong (1)

nemasu (1766860) | about 6 months ago | (#47072783)

Basically, according to the Big Bang theory, something that large that far away (old) should not exist.

Re:Theory as it stands is wrong (0)

Anonymous Coward | about 6 months ago | (#47072815)

Isn't there a problem with the universe being 14 billion years old and the observable part having a radius of 46 billion light years too?

Re:Theory as it stands is wrong (5, Informative)

oneandoneis2 (777721) | about 6 months ago | (#47072833)

No.

Look up inflation.

Re:Theory as it stands is wrong (2)

Sockatume (732728) | about 6 months ago | (#47072837)

Nope; because of metric expansion, objects whose light we are now receiving can be further away than the product of the speed of light and the age of the universe.

Re:Theory as it stands is wrong (4, Interesting)

Charliemopps (1157495) | about 6 months ago | (#47073327)

To explain further... metric expansion is the central premise of the big bang theory. SPACE is growing larger... the matter within it is not moving away from each other. (well they might be but that's not relevant) So if you and I were standing next to each other and not moving, the distance between us would still be growing. On small scales the effect isn't even measurable it's so small. But the effect increases with the more distance between us. When you get to galactic scales the effect is enormous. The speed of light limit is a result of the geometry of space-time. Think of it like a right triangle... you change one line, and that affects the angles and lengths of the others. Expansion is like changing the size and shape of the paper the triangle is drawn on.

Or at least that's always been my understanding. Physicists feel free to correct me. Time Cube guys, stay out of it. :-)

Re:Theory as it stands is wrong (1)

Rob Riggs (6418) | about 6 months ago | (#47074323)

And gravity still affects the mass in space as it expands, so that items that are strongly gravitationally bound remain so. Yet items that are weakly bound can grow apart.

Bonus question: how does this expansion affect the orbits of planets around stars and the orbits of stars in a galaxy?

Re:Theory as it stands is wrong (3, Funny)

myowntrueself (607117) | about 6 months ago | (#47078441)

Nope; because of metric expansion, objects whose light we are now receiving can be further away than the product of the speed of light and the age of the universe.

So in the US they have imperial expansion? Of course, that explains a lot!

Re:Theory as it stands is wrong (1)

wjcofkc (964165) | about 6 months ago | (#47077647)

Perhaps it was an engineering effort.

Re:Theory as it stands is wrong (2)

Sockatume (732728) | about 6 months ago | (#47072799)

It doesn't, as far as I can tell; the citation given in the article doesn't actually mention any of the assertions made in that section. What the Great Wall does cause problems with is the "cosmological principle": that the universe is largely isotropic, i.e. smooth.

Re:Theory as it stands is wrong (1)

nemasu (1766860) | about 6 months ago | (#47072847)

Hmm, I guess technically you are correct, can the Big Bang theory still be valid if the cosmological principle is incorrect? I assumed they were kind of tied together.

Re:Theory as it stands is wrong (5, Informative)

Sockatume (732728) | about 6 months ago | (#47072865)

The issue is that the big bang implies the universe is fairly isotropic; it can be clumpy to a certain degree, and the exact degree of clumpiness depends on the exact model you use. Although this Great Wall is a bigger clump than current models allow, you can imagine that there could be other big bang models where the allowed clumpiness is a bit larger. (In fact we know from other observations that we will have to come up with slightly different big bang models than the ones we currently use anyway.)

Re:Theory as it stands is wrong (3, Interesting)

nemasu (1766860) | about 6 months ago | (#47072869)

Ah, so what you're saying is that the current theory is not disproved, but the current model of the theory.
Well don't I feel silly now.

Re:Theory as it stands is wrong (2)

Sockatume (732728) | about 6 months ago | (#47072883)

Yeah, the current flavour of big bang if you like. The idea of a big bang itself is pretty robust at this point, but while we've spent a good long time figuring out exactly what happened, the existence of this Great Wall implies that we're off track.

Re:Theory as it stands is wrong (2)

meglon (1001833) | about 6 months ago | (#47073145)

But that's not the only possibility. We know how big the observable part of the universe is.... what we don't know is how big it is beyond that, and the estimates are all over the board. The Great Wall may simply mean we're not thinking in a big enough scale. Now that's a brain shaker.... the entire observable universe being nothing more than a small, insignificant, backwater blip in the grand scheme of things.

Re:Theory as it stands is wrong (1)

Sockatume (732728) | about 6 months ago | (#47073227)

Indeed, it might imply that the whole cosmology is wrong in some way and we need a new one, although that's less likely than some little tweak to the existing one.

Re:Theory as it stands is wrong (1)

meglon (1001833) | about 6 months ago | (#47079991)

The scale/relationship i mentioned doesn't throw out the inflation model, in fact it fits well within it. In "The Inflationary Universe" by Guth, he suggests that the entire universe may be 3x10e23 larger than the observable universe (pg 186 if you're interested).

Re:Theory as it stands is wrong (4, Insightful)

Eunuchswear (210685) | about 6 months ago | (#47073027)

Essentially, all models are wrong, but some are useful.

-- George E. P. Box

Re:Theory as it stands is wrong (0)

Anonymous Coward | about 6 months ago | (#47074107)

can the Big Bang theory still be valid if the cosmological principle is incorrect?

As long as the ratings remain high, The Big Bang Theory will be valid regardless of any cosmological principle.

Re:Theory as it stands is wrong (1)

MozeeToby (1163751) | about 6 months ago | (#47073641)

Because it's "lumpier" than the universe should be based on our current understanding. At sufficiently large scales, any one section of the universe should look basically like any other section. The Hercules-Corona Borealis Great Wall (and other features of similar size) are above the "sufficiently large" scale so we don't expect to see organized structures but we do, so our understanding isn't complete (which is hardly surprising).

Re:Theory as it stands is wrong (0, Troll)

UnknownSoldier (67820) | about 6 months ago | (#47074283)

Depending on who you talk to, evidence either contradicts or makes the Big Bang incomplete.

Wikipedia Big Bang [wikipedia.org] mentions these 3 problems:

* the horizon problem,
* the flatness problem,
* and the magnetic monopole problem.

The typical kludge is "Cosmic Inflation [wikipedia.org] ", but that hack creates even more problems. (" inflation is the expansion of space in the early universe at a rate much faster than the speed of light temporarily.") Paul J. Steinhardt, one of the founding fathers of inflationary cosmology, has recently become one of its sharpest critics.

There are numerous other problems with the Big Bang:

The first law of thermodynamics says Energy can neither be created nor destroyed, only change form, yet "magically" the Big Bang appeared out of nothing ?!?!?
* The Big Bang attempts to explain "How", but it still doesn't explain why it happened in the first place?

I've included the top 11 of the full list of 30 Problems of the Big Bang [metaresearch.org] :

* Static universe models fit observational data better than expanding universe models.
* The microwave "background" makes more sense as the limiting temperature of space heated by starlight than as the remnant of a fireball
* Element abundance predictions using the Big Bang require too many adjustable parameters to make them work.
* The universe has too much large scale structure (interspersed "walls" and voids) to form in a time as short as 10-20 billion years.
* The average luminosity of quasars must decrease with time in just the right way so that their average apparent brightness is the same at all redshifts, which is exceedingly unlikely.
* The ages of globular clusters appear older than the universe.
* The local streaming motions of galaxies are too high for a finite universe that is supposed to be everywhere uniform.
* Invisible dark matter of an unknown but non-baryonic nature must be the dominant ingredient of the entire universe.
* The most distant galaxies in the Hubble Deep Field show insufficient evidence of evolution, with some of them having higher redshifts (z = 6-7) than the highest-redshift quasars.
* If the open universe we see today is extrapolated back near the beginning, the ratio of the actual density of matter in the universe to the critical density must differ from unity by just a part in 1059. Any larger deviation would result in a universe already collapsed on itself or already dissipated.
* Under Big Bang premises, the Fine Structure Constant [wikipedia.org] must vary with time. WHOOPS! Feynamn, founder of QED, once wrote:

There is a most profound and beautiful question associated with the observed coupling constant, e - the amplitude for a real electron to emit or absorb a real photon. It is a simple number that has been experimentally determined to be close to 0.08542455. (My physicist friends won't recognize this number, because they like to remember it as the inverse of its square: about 137.03597 with about an uncertainty of about 2 in the last decimal place. It has been a mystery ever since it was discovered more than fifty years ago, and all good theoretical physicists put this number up on their wall and worry about it.) Immediately you would like to know where this number for a coupling comes from: is it related to pi or perhaps to the base of natural logarithms? Nobody knows. It's one of the greatest damn mysteries of physics: a magic number that comes to us with no understanding by man. You might say the "hand of God" wrote that number, and "we don't know how He pushed his pencil." We know what kind of a dance to do experimentally to measure this number very accurately, but we don't know what kind of dance to do on the computer to make this number come out, without putting it in secretly!

Notice the discrepancy between his accepted value 0.08542455 and the modern one of 0.0729735257 !

Re:Theory as it stands is wrong (1)

UnknownSoldier (67820) | about 6 months ago | (#47074587)

Correction: I meant 1/137.03597 = 0.00729735411805, NOT e = 0.08542455

1/137.03597 with about an uncertainty of about 2 in the last decimal place gives us:

* max 137.03599 = 0.0072973530... still too large
* min 137.03595 = 0.007297355... WAY too large

The modern a = 0.00729735257, looks like Fenyman should of said with about an uncertainty of about 3 in the last decimal place.

Re:Theory as it stands is wrong (1)

suutar (1860506) | about 6 months ago | (#47076593)

"they like to remember it as the inverse of its _square_" (emphasis mine). You need to take the square root of your 0.007... to get the comparable number. sqrt(0.0072973530) is .085424557359 and sqrt(0.007297355) is .085424545652, each of which, rounded to the proper number of figures, matches Feynman's figure.

Re:Theory as it stands is wrong (1)

suutar (1860506) | about 6 months ago | (#47076635)

Or, going the other way, 0.08542455 ^ 2 => .007297353742, and 1/0.007297353742 => 137.035977061724

Re:Theory as it stands is wrong (1)

UnknownSoldier (67820) | about 6 months ago | (#47077613)

Yes, thanks, I already corrected that mistake 3 hours earlier.

Re:Theory as it stands is wrong (1)

suutar (1860506) | about 6 months ago | (#47099703)

Ah, gotcha. You appeared to be comparing 0.08 to 0.007 and I missed the e vs a part.

Bothered (1)

symes (835608) | about 6 months ago | (#47072787)

IANA astro-physicist - but something bothers me about the big bang theory (or at least what I know about it). Why just one? Why aren't we able to detect other big bangs elsewhere? And another thing - we theorise based on what we are able to measure and observe. While we seem to have a theory that fits the data available, surely it is quite possible that our data are just unique to our locality. Seems like we are looking into someone's CA backyard and trying to say something about volcanic action in Iceland.

Re:Bothered (3, Funny)

u38cg (607297) | about 6 months ago | (#47072841)

Well, when you create a theory of the universe's creation, you should probably take a hint from the name "universe" that there will be just one starting point...

Re:Bothered (2)

gl4ss (559668) | about 6 months ago | (#47072867)

well if you could somehow transport yourself to outside of this universe you might be able to observe the other big bangs.

hoooowever there's some significant problems with doing that. some people believe that if you jump from a bridge into concrete you get outside though(they base this on a lucid revelation given to someone else than them).

really though you don't need to be an astrophysicist to understand the basis for why your question sounds very misinformed. volcanic action in iceland is observable from california to some extent. quite well too if you include technical means like getting measurement readings from sensors in Iceland. to observe other big bangs you would need to in another universe than Iceland is in, which would make all sensor readings and communication impossible(you can only theorize if there's a multiverse or not, since everything you can possibly see is in this one universe that we are in).

in short: universes are not like galaxies that are _inside_ an universe. universe is what all the galaxies, background radiation and everything else we can see are in. the universe isn't like a room in a house but the universe is like the universe the house is in.

Re:Bothered (4, Interesting)

Sockatume (732728) | about 6 months ago | (#47072875)

That's a legitimate question, and in fact cosmologists are curious about the idea of whether the big bang is a unique event or something that can happen spontaneously. The hope is that advanced physics will provide some answers.

As for the "locality" issue: cosmologists address issues related to the entire observable universe. Speculations on regions that are unobservable aren't really a topic for scientific investigation, except where a good model implies certain (untestable) things about unobservable areas.

Re:Bothered (3, Interesting)

mbone (558574) | about 6 months ago | (#47073265)

In "eternal inflation," inflation is seen as something like the natural state of the universe, with little nodes from time to time budding off of the inflationary stream, and forming universes like our own, with inflation continuing elsewhere (from our standpoint, very very far away, much beyond any distance we could reach, even if we traveled at the speed of light). In such theories, the big bang is not the time of the birth of the universe, it is the time of the cession of inflation here, in our part of this bigger universe. This is one type of what Max Tegmark calls a Level I Multiverse (as there would be other "big bangs" elsewhere).

It may be that the recent detection of cosmic acceleration (aka "dark energy") indicates that our universe may (if the acceleration itself starts to accelerate into something like a "big rip") return to this natural state of inflation in due course, and that might be the typical fate of "normal" universes like ours.

because of the cosmological principle (0)

Anonymous Coward | about 6 months ago | (#47074119)

There are two main principles closely related to each other that are rarely mentioned but always exist in the foundation of any such theory:
the assumption that we are not in any special place in the universe (i.e. what we observe its more or less the same regardless of where we are)
and the assumption that the laws of physics are the same everywhere
That is also known as the the cosmological principle.
One could argue that there is no reason to think that is the case but then we stray into philosophy and cosmologists get panic attacks

Re:Bothered (1)

TangoMargarine (1617195) | about 6 months ago | (#47074253)

I was under the impression that the big bang needed conditions that would no longer exist in our post-bang universe (absence of time or something...), which would preclude further big bangs in our light cone. Although presumably they could still happen "outside" the universe?

Neutrino temperature (5, Interesting)

Framboise (521772) | about 6 months ago | (#47072873)

The orginal article keeps quoting the temperature of 1.96K as the neutrino background temperature, as found in most textbooks on the topic. This is a relic of the time people were assuming massless neutrinos. The confusion is maintained by people using the temperature as a synonym of energy. Actually the non-zero rest mass energy must be subtracted, providing the real kinetic energy of these particles (moving now at 100-1000 km/s) that would be exchanged with a super large thermometer (in view of the tiny interaction cross section). The effective neutrino temperature would then be measured in the milliKelvin range.

 

Re:Neutrino temperature (0)

Anonymous Coward | about 6 months ago | (#47078097)

Has an actual lower bound been placed on neutrino masses? I'm aware of many experiments/effects that place upper bounds between eV and meV but don't recall any lower limits.

2K is about .2meV which is ~ some predicted masses. But without knowing something of the actual masses, it's impossible to say what temperature would actually be measured since the neutrinos' rest mass sets the point at which universe expansion stops diluting away their kinetic energy (relativistic particles redshift, nonrelativistic don't). So if the relic neutrinos have reached the nonrelativistic regime, their temperature will be somewhat less than their rest mass. If we could actually get a temperature measurement of such things, that would be fantastic because it would I believe allow us to pin down the neutrino's mass quite exactly (Yes, I know, differing masses, but the splittings are small).

Fun times in astrophysics...

Re:Neutrino temperature (1)

Anonymous Coward | about 6 months ago | (#47081243)

Has an actual lower bound been placed on neutrino masses?

Yes, on two of the three neutrinos because we have measurements of the difference in their masses. The lightest could still be pretty light, but knowing there has to be a certain difference between them means the other two can't be lighter than the difference.

Possible the greatest story every told (-1)

Anonymous Coward | about 6 months ago | (#47073035)

But just a story with an ever changing story line when it suits the writers. And just a theory, like Scientology.

Re:Possible the greatest story every told (1)

Immerman (2627577) | about 6 months ago | (#47074427)

Sorry, but Scientology isn't a theory - at best it's a wacky hypothesis. A hypothesis must make definite useful predictions and withstand many and varied attempts to disprove it before it gets promoted to a theory (which is, roughly, synonymous with a scientific law)

As for the story changing - absolutely, that's called "learning", a concept you may be familiar with. I'd bet your own story as to where babies come from, or what women want (or men,as appropriate) has changed considerably since you first asked the question. The alternative is to continue to cling to a story that has either been proven false, or is interpreted in such a metaphorical context as to render it irrelevant to physical reality.

Not quite (5, Interesting)

mbone (558574) | about 6 months ago | (#47073221)

...the only interaction they can conceivably have with normal matter is via a nuclear recoil.

No, not quite. These neutrinos also interact gravitationally with ordinary matter, which, of course, the author knows, but just doesn't think of. That introduces two possible means of detecting them, either gravitationally [arxiv.org] , or by using the Sun or other bodies to focus them [arxiv.org] on a detector, thereby greatly amplifying their signal.

Re:Not quite (1)

Immerman (2627577) | about 6 months ago | (#47074541)

The thing is gravitational interactions are so minute as to be useless (for now) for detecting individual neutrinos in a laboratory environment - the sort of situation which lets you conclusively state the things actually exist and aren't just a flawed theoretical construct used to help explain things we see halfway across the observable universe.

The focussing thing sounds like it has promise though, though I wonder just how much good focussing something so far beneath our current detection thresholds can do Even a thousandfold increase in the rate of undetectable interactions is likely still undetectable. That second paper also seems to be making the assumption that CvM neutrinos would be orbitting in the galactic plane, which seems vaguely ridiculous at first glance - anything we're seeing today presumably originated outside our galaxy, and are interacting only gravitationally, so what mechanism would organize them into the galactic disc, instead of just orbiting the galaxy as a disorganized cloud - and even that assumes they have slowed down considerably after entering our galaxy, or they'd simply follow a hyperbolic "orbit" back out into intergalactic space.

Re:Not quite (0)

Anonymous Coward | about 6 months ago | (#47074795)

The gravitational interaction is actually major focus of current research. This is how you can measure the neutrino mass using the cosmic microwave background and other cosmological probes.

Re:Not quite (1)

Immerman (2627577) | about 6 months ago | (#47075645)

I misspoke, that should have been "for detecting individual slow neutrinos"

For measuring the neutrino mass perhaps - but is anything directly related to detecting slow neutrinos from the cosmic neutrino background radiation? My impression was that detecting such neutrinos is still well outside our current abilities, the energies involved are just too small.

It still does not answer the biggest question... (3, Funny)

Lumpy (12016) | about 6 months ago | (#47073243)

Will Sheldon finally find a way to communicate with Penny?

Re:It still does not answer the biggest question.. (-1)

Anonymous Coward | about 6 months ago | (#47073537)

The biggest question should be:
Where did all the stuff come from ?
We are to believe it all was packed into a small dot.
Then from that dot was the big-bang and all the stuff came out of it.
It's just too comic of a theory to believe !
Anyway. let assume for a short moment the theory is correct.
Still a problem, where did that strange dot come from ?

Re:It still does not answer the biggest question.. (1)

wjcofkc (964165) | about 6 months ago | (#47077919)

Where did all the stuff come from ?

E = M C2

That's about all there is to it.

Re:It still does not answer the biggest question.. (1)

Anonymous Coward | about 6 months ago | (#47073935)

Botswana.

ROFL (-1)

Anonymous Coward | about 6 months ago | (#47073311)

" the Big Bang still thrives as the most successful scientific model of the Universe ever constructed."

Really? Then give us proof where all of that matter came from so the big bang could happen. If it already existed to allow the big bang to occur, then where did it come from before that?

Re:ROFL (5, Insightful)

paiute (550198) | about 6 months ago | (#47073427)

" the Big Bang still thrives as the most successful scientific model of the Universe ever constructed."

Really? Then give us proof where all of that matter came from so the big bang could happen. If it already existed to allow the big bang to occur, then where did it come from before that?

A degree in cosmology takes years of study and research. A degree in cosmetology can be obtained in six months. Your girlfriend will laugh and ridicule your opinions in cosmetology, but you feel fully qualified to comment on the current questions being studied in cosmology.

Re: ROFL (1)

ceoyoyo (59147) | about 6 months ago | (#47073751)

Well played. I'll have to remember that response.

Re:ROFL (1)

Kjella (173770) | about 6 months ago | (#47074593)

Your girlfriend will laugh and ridicule your opinions in cosmetology

Guys with degrees in cosmetology don't have girlfriends, no matter how many chicks you see them hanging out with.

Re:ROFL (1)

Sockatume (732728) | about 6 months ago | (#47073637)

Nobody knows. Although we know that it was there, and it was in a hot dense state.

Note that "nobody knows" does not mean "whatever pet theory you have is right".

Re:ROFL (2)

TangoMargarine (1617195) | about 6 months ago | (#47074327)

Go watch Primer [wikipedia.org] a couple times and then come back and see if you still want to ask that question.

I suspect why everyone gets pissed at this question--assuming it's not just a knee-jerk anti-creationism reaction--is that the question doesn't really "mean" anything. It's like asking someone, "Who was phone?" There's at least one model [wikipedia.org] that posits that ball or some version of the universe has "always been there."

Plus, isn't talking about "before the big bang" paradoxical since time itself technically didn't exist "then"?

#quitepossiblycompletelyfullofcrap

Origin of mass-energy (1)

Immerman (2627577) | about 6 months ago | (#47074609)

You're obviously trolling, but what the hell:

One of the current theories with some traction is that inflationary energy was self-replicating, capable of "separating" flat space into more inflationary energy and the corresponding gravitational well (negative energy potential), for net zero change in total energy. The inflationary energy then later decayed into what we today call mass and energy.

That is to suggest that the entire universe contains a net mass-energy of approximately zero - all positive mass-energy is perfectly balanced by it's negative gravitational potential, and it's only that initial separation that allows anything to exist at all.

Re:ROFL (1)

Rakarra (112805) | about 6 months ago | (#47078611)

My understanding of the Big Bang Theory, from Hawking's books, is that the theory doesn't try to address what came before the big bang. Or what set it in motion. How how this something came from nothing or if there was a "nothing."

All it attempts to explain is, once it starts, how does it proceed?

Big Bang does not explain (0)

Anonymous Coward | about 6 months ago | (#47073451)

Why is it: Almost everything IN the universe is a blob and an accretion disk, Earth-Moon, Sun-Planets, spiral galaxies, etc.
But the universe as a whole is uniform. It would imply that the universe was not spinning before the Big Bang.
Or that some outside force Ripped the universe apart, a force that was stronger than the force of the universe's spin energy.

Quantum fluctuations (2)

GlowingCat (2459788) | about 6 months ago | (#47073619)

If quantum fluctuations created the big bang, than what created the quantum fluctuations ?

Re:Quantum fluctuations (1)

Immerman (2627577) | about 6 months ago | (#47074745)

They are, have been, and ever shall be.

We know that today various so-called "virtual particles" spontaneously pop into existence for a brief moment before annihilating with the antiparticle that spawned along with them - the theory stands up and we can measure their effects in the lab. And there's no reason to assume the same thing hasn't been happening throughout eternity.

And I mean actual eternity - not just the paltry 14 billion years since the big bang. For all eternity virtual particles could have been popping in and out of existence, and if ever a single spec of virtual inflationary energy popped into existence and was able to do it's thing, separating flat space into a spec of "real" inflationary energy whose energy-debt is paid in full by its corresponding gravitational well, then BOOM it spreads across the cosmos like wildfire, creating more traditional mass and energy in its wake as it decays.

Re:Quantum fluctuations (1)

sjames (1099) | about 6 months ago | (#47075779)

It was probably turtles.

It not only accounting for phenomena (1)

Curunir_wolf (588405) | about 6 months ago | (#47073955)

... but it be good too!

Obvious troll is obvious (1)

TangoMargarine (1617195) | about 6 months ago | (#47074227)

Come on, DICE: If you're going to troll us with articles, at least try to make it a bit more subtle. This one basically reads as "Evolution is best science EVARRRR!!"

It not only accounting for phenomena

Glad to see the editors we know and love are still living up to the high standards we set for them, too.

most successful? (-1)

Anonymous Coward | about 6 months ago | (#47074595)

The most successful scientific model is found in Genesis chapter 1. It begins with the creation of light.

Re:most successful? (2)

Markvs (17298) | about 6 months ago | (#47074885)

The most successful scientific model is found in Genesis chapter 1. It begins with the creation of light.

Well, yes. That's what the Big Bang Theory is in a nutshell, and it was after all originally developed by Georges Lemaitre, a Belgian Catholic Priest.
It's notable that all of the planet's major religions endorse the BBT and consider it to not be at odds with their faith including Christianity, Islam, Hinduism, Buddhism, & Judaism.

Actually, a really nice article... (2)

rgbatduke (1231380) | about 6 months ago | (#47074815)

That was really lovely, and thank you for posting it.

You assert that one problem with detection is the difficulty of accelerating entire neutrino detectors to GeV energy scales. I'm not sure that I agree. Muons, as we know, decay into electrons and two kinds of neutrino/antineutrino. Electrons moving at GeV scales have more than enough energy to be transformed into muons in the inverse reaction -- if they happen to hit an electron antineutrino -- or more properly, they have a chance to be transformed into a W- boson which can then decay into several things -- lepton/neutrino pairs or quark pairs, one of which produces muons

Muons are easy to detect. Electrons with "suddenly" shifted energy are also easy to detect (another possible outcome). Finally, quark-antiquark "jets" are easy to detect.

At the densities of thermal neutrinos asserted, it seems reasonably probable (without, admittedly, doing the computation) that GeV scale electrons will encounter free neutrinos and undergo the inverse reaction and produce muons along a freely moving beam track and indeed that places like SLAC and the Duke FEL would be producing a small but detectable flux of muons all along the straight legs of their beams that would then either exit sideways (where they could be detected lots of ways) or continue along the collision frame of reference and be moderately separable at the next bending magnet. Yes, there would likely be some auxiliary production near the actual beam from electron collisions with beam pipe metal outside of the beam envelope, but one would expect to be able to put a vacuum pipe along the frame of reference of the collision a kilometer long or thereabouts PAST a a bending magnet (at the right angle) at the end of a long straight leg and run it into a detector, which would then detect all/mostly muons produced by neutrino scattering. Or so it seems.

Is this wrong?

rgb

Re:Actually, a really nice article... (1)

amaurea (2900163) | about 6 months ago | (#47077765)

I think you are overestimating the scattering cross section of even GeV neutrinos. An electron neutrino with 10 GeV in the rest frame of an electron has a scattering cross section of about 2e-44 m^2. There are about 112 electron neutrinos per cm^3, so the (lab frame) scattering rate is about 2e-44 m^2 * c *112/cm^3 = 6.7e-28/s per electron. The number of protons per beam in LHC is about 1e14. Assuming the number of electrons per beam in SLAC etc. is roughly the same, we get about 1e-13/s scatterings total in the beam. So to get a single scattering one would expect to have to wait about 300000 years (assuming I didn't mess up this back-of-the-envelope calculation).

This is the reason why neutrino detectors are so huge - they have to overcome the tiny scattering rate with a huge number of potential targets. That's why the article is saying one would have to accelerate a whole neutrino detector.

Re:Actually, a really nice article... (1)

rgbatduke (1231380) | about 6 months ago | (#47082693)

Thanks, you are probably right -- as I said, I wasn't doing the math, but was just thinking that an accelerated beam IS a rapidly moving detector. I was also assuming that it was the lack of collision frame energy in the huge neutrino detectors that was the limiting factor in detecting thermal neutrinos -- to create a W boson requires order of 100 GeV, and of course this just isn't available (outside of Heisenberg uncertainty and extremely suppressed virtual processes) which mutually thermal atoms and neutrinos. But creating a 100 GeV/c^2 electron beam has actually been done (LEP) specifically to enable the creation of the heavy vector bosons in particle/antiparticle collisions (which peaked out around 209 GeV/c^2). I would have expected the thermal neutrino cross-section to take a dramatic uptick once the frame energy was sufficient to actually enable the direct process -- even in the huge detectors in use a major problem is that the neutrinos coming in don't have ~100 GeV/c^2 in the collision frame, right?

I think LEP was shut down and its tunnel re-purposed into the LHC, and I'm guessing the LHC can't be used to accelerate a lepton beam without basically rebuilding it, so there may be no machine currently in existence that could do this anyway (I should have thought more carefully about the collision frame issue and the W rest mass when I suggested SLAC or the FEL could do this -- they are still well below the threshold for producing W's from thermal neutrinos (SLAC is close at 50 GeV/c^2). But if the cross section issue IS lack of frame energy as opposed to probability of encounter (as seems likely -- there are going to be plenty of close encounters between electrons and neutrinos in a long run even with a comparatively low neutrino density, but one has to have at least enough energy to create a W for at least enough time to make it a virtual channel for the final muon and antineutrino. I'm guessing that we don't have measurements for the cross section at these frame energies (unless there is data from LEP somewhere), but the possibility of a resonance or cross-section spike once the W threshold is passed is hardly unreasonable.

Re:Actually, a really nice article... (1)

amaurea (2900163) | about 6 months ago | (#47082961)

Yes, the accelerated beam is a rapidly moving detector. My point is that it is a rapidly moving detector with a woefully tiny volume. I'm no expert on this - I used this page [cupp.oulu.fi] for neutrino cross sections. Both inelastic and elastic scattering seems to be proportional to collision energy.

Neutrinos of several PeV/c^2 are regularly observed in neutrino observatories. At these energies, the Earth is able to act as a somewhat effective neutrino shield, resulting in a significant deficiency in high-enery (>60 TeV) neutrino flux from the direction of the ground [arxiv.org] (i.e. the direction shielded by the Earth). That says something about how difficult even extremely high energy neutrinos are to detect: Even a detector the size of the Earth lets through quite a bit of them.

It seems you're right that having enough energy to create W-bosons in the collision frame does give the cross section a huge boost, though. There is a really nice figure showing this on page 3 of the article From eV to EeV: Neutrino Cross-Sections Across Energy Scales [arxiv.org] (note: That figure only shows one of several possible scattering processes - see page 40 for more details). But as the other poster pointed out, to get 100 GeV/c^2 in the collision frame, you need much higher energy when only one particle is moving. In this figure, that point seems to be about 6 PeV. So extragalactic ultra-high-energy neutrinos aren't that far away from that point. But particles in our accelerators have far too low energy.

Re:Actually, a really nice article... (1)

rgbatduke (1231380) | about 6 months ago | (#47083113)

Interesting article. Things really do get complicated at those energy scales...:-)

They're using Cerenkov detectors, though, for very very high energy events. I wonder how sensitive they are to muons with much lower energies. The scales on the figures in the article, for example, don't actually go down to 100 GeV -- the left hand edge (log scale) appears to be 1 TeV. But the cross sections are indeed pretty small and it is difficult to get rates to rise above the background cosmic ray muon flux (which I actually measured, once upon a time back in the 70's before I became a theorist:-).

I suppose the only unresolved question would be whether or not there is a narrow but strong electron-electron neutrino resonance around the rest mass of the W-. The collision volume (even summed over the length of the beam column in e.g. a SLAC-like pipe) is quite small, but SLAC is apparently capable of generating 1/2 an ampere of beam current. That's basically 10^19 electrons/second, which knocks five orders of magnitude off your estimate of 1 event per 300000 years to one per 3 years. That seems as though it is low enough that IF there were any sort of actual resonance, it might knock another order of magnitude off and get one at least several events per year, maybe more. Nobel prizes have been won with little more...:-)

Is the seat of the pants estimate sufficient it to propose doubling SLAC's peak energy and current and designing a custom beanding magnet at the end of a long otherwise empty beam pipe to resolve resonant muons from background? Maybe not, but it might be part of a proposal that included other experiments (including a revival of its experiments to search for Higgs, for example) that might benefit from a substantially beefed up beam.

Of course the REALLY cool way to do this would be to do it either on the moon or at one of the Lagrange points -- someplace where 100 km beams don't require either Earth-expensive real estate or tunnels or pipes, and where solar energy could provide a gigawatt of "free" power once you built the facility. Really cool and awesomely expensive, but imagine using the polar moon to build a ring and the equatorial moon to build a "linear" (great circle curvature) accelerator. Even a theorist can appreciate that...

Imagine doing an experiment to scatter electrons off of thermal big bang photons, for example, doppler shifted up to GeV scales. Which is similarly difficult, actually.

I once upon a time fantasized about creating some sort of "wiggler" in the electroweak interaction that could resonantly convert electrons into muons along the lines of the way FELs create a "virtual photon" in the electron rest frame. If one could ever make this sort of thing efficient enough, one could revisit the issue of muon-catalyzed fusion and maybe do an end run around thermal confinement problems. My Ph.D. advisor (Larry Biedenharn) spent a decade or so looking hard at muon catalyzed fusion so I learned a lot about it then even though my research was in completely different stuff). The primary block point was the huge cost per muon to create muons via e.g. nuclear cross sections and pion decay. If one could ever short circuit that, the issue would be worth revisiting even with the other problems, just for the pleasure of the physics...

rgb

Re:Actually, a really nice article... (1)

amaurea (2900163) | about 6 months ago | (#47085085)

The scales on the figures in the article, for example, don't actually go down to 100 GeV -- the left hand edge (log scale) appears to be 1 TeV.

Sorry, my third link was to the wrong article. It should have been this one [arxiv.org] . That's the one that covers the whole energy range, and which shows the magnitude and location of the W-boson resonance.

SLAC is apparently capable of generating 1/2 an ampere of beam current. That's basically 10^19 electrons/second, which knocks five orders of magnitude off your estimate of 1 event per 300000 years to one per 3 years.

Wow, I was off by a lot! I don't know how noisy environments accelerators are, but I think one would need many times more events per year to be able to detect this. It would be really nice.. But I'm skeptical.

That seems as though it is low enough that IF there were any sort of actual resonance, it might knock another order of magnitude off and get one at least several events per year, maybe more.

From the figure on page 3 in the article, it seems like the W resonance is at 6 PeV/c^2 for a stationary neutrino being impacted by a moving electron, or vice versa. I think that makes sense from a momentum convervation point of view. I haven't done relativistic kinematics in a long while, but the available energy in a collision is E_a^2 = 2 E_1 E_2 + (m_1c^2)^2 + (m_2c^2)^2, so for a massless impactor (m_1=0) hitting an stationary electron (m_2 = m_e, E_2 = m_e c^2) to have 80 GeV/c^2 (W mass) of available energy, we need E_1 = sqrt((E_a^2-E_2^2)/(2E_2)) = 6.3 PeV/c^2. If you go significantly below that energy, there isn't enough available energy to produce a W without violating momentum conservation. So I don't think there's much hope for an accelerator electron getting this resonance with the cosmic neutrino background. :/
Unless I've missed something crucial here. But perhaps we'll have a breaktrough in accelerator technology that will let us reach these levels at some point. If we hit the resonance, the scattering rate will be of the order 1e-31, 13 orders of magnitude higher than what I used in my back-of-the-envelope calculation. But we aren't likely to hit those energies soon, I think.

My Ph.D. advisor (Larry Biedenharn) spent a decade or so looking hard at muon catalyzed fusion so I learned a lot about it then even though my research was in completely different stuff). The primary block point was the huge cost per muon to create muons via e.g. nuclear cross sections and pion decay.

Yes, I've been interested in muon catalyzed fusion myself. It's such a nice idea. A way to reduce the cost of muon production would be very nice.

Re:Actually, a really nice article... (1)

rgbatduke (1231380) | about 6 months ago | (#47091511)

Unless I've missed something crucial here. But perhaps we'll have a breaktrough in accelerator technology that will let us reach these levels at some point. If we hit the resonance, the scattering rate will be of the order 1e-31, 13 orders of magnitude higher than what I used in my back-of-the-envelope calculation. But we aren't likely to hit those energies soon, I think.

Oops (blush). I haven't done relativistic kinematics for a very long while either, but I forgot about momentum conservation altogether. And here I am teaching undergrads about inelastic collisions...

Well darn. It looks like it could borderline work in the sense of produce events every month or even more if one could get TeV electrons at beam currents of order 1 ampere, but you're right, getting to the PeV resonance will be, err, difficult. OK, so probably not worth rebuilding SLAC for.

As for muon catalyzed fusion, Larry's last idea on the subject was politically incorrect but intriguing. He suggested using it as an energy boost second stage gleaning muons from fission reactors. But even then (20+ years ago) fission reactors were politically incorrect and there wasn't a lot of enthusiasm for the idea. I never worked out the math (I assume he did, somewhere) to see if there were enough muons per fission and enough fusions per muon to get a significant gain in net nuclear fuel yield, though.

Re:Actually, a really nice article... (1)

amaurea (2900163) | about 6 months ago | (#47084937)

Oops, I mistakenly used the same link twice. The last link was supposed to be this:
http://arxiv.org/pdf/1305.7513v1 [arxiv.org]
It is well worth a look through.

Re:Actually, a really nice article... (0)

Anonymous Coward | about 6 months ago | (#47078243)

The problem is one of the cute things they make you work out in relativistic kinematics. Given two particles with laboratory frame momenta p1 and p2, what is the center-of-mass (frame where p1 = -p2) energy, because this is what determines if your two particles can interact and create other things.

A bit of algebra later, you find that if p2 = 0, the CoM energy scales as the square root of p1 while if they are equal and opposite in the lab frame, it simply scales linearly as p. This is why particle accelerators abandoned target-bombardment and switched to counter-rotating beams long ago. Unfortunately, if the relic neutrinos are nonrelativistic, that means we're in a target-bombardment scenario (as they're basically standing still relative to any particle accelerator beam) and so the CoM energy and the cross section are shot all to hell.

And since the relic neutrinos have practically no kinetic energy left, relativistic or not, good luck detecting something with meV of kinetic energy bumping an atom/molecule with a mass of 1-200GeV. If you can come up with any remotely feasible way to directly pick up relic neutrinos, you'll be the first...

Finally (0)

Anonymous Coward | about 6 months ago | (#47076689)

That Nobel prize will be mine ....

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