Loophole in theory offers insight into the 'lithium problem'

March 12, 2015 by Lisa Zyga feature
Figure showing constraints on the primordial lithium abundance. A loophole in the way that electromagnetic cascades are computed opens up the possibility of solutions to the lithium problem. Credit: Poulin and Serpico. ©2015 American Physical Society

(Phys.org)—There's not as much lithium in the universe as predicted, and scientists aren't sure why. According to the theory of big bang nucleosynthesis (BBN), isotopes of the three lightest elements—hydrogen, helium, and lithium—were created within the first 20 minutes after the big bang. The theory predicts with remarkable accuracy the observed amounts of hydrogen and helium, but its estimate for lithium is three times too high.

The problem has frustrated scientists working in cosmology, since almost any modification to the BBN theory that corrects the lithium abundance inadvertently throws off the hydrogen or helium abundances, or contradicts other constraints on the theory. The situation may be compared to trying to solve a Rubik's cube that has only one square of the wrong color.

Now in a new paper published in Physical Review Letters, physicists Vivian Poulin and Pasquale Dario Serpico at Université Savoie Mont Blanc, CNRS, in Annecy-le-Vieux, France, have suggested that the lithium problem may be connected to an overlooked loophole in another theory: that of electromagnetic cascades. Although addressing the lithium problem is not the main result of the paper, it illustrates the potential impact of these broader findings.

"The general result we found in our paper is not specifically related to the lithium problem, rather to the inaccuracy of an approximation used to describe perfectly standard physics, related to cascades," Serpico told Phys.org.

An electromagnetic cascade refers to the cascade of particles produced from a collision between photons and/or electrons. Such a collision results in a chain of reactions in which energy is redistributed among larger numbers of particles, where the energy per particle decreases.

The standard theory of electromagnetic cascades describes this redistribution of energy by predicting a specific shape of the spectrum of photon energies in the cascade. Many different areas of research, including BBN theory, have used this spectral shape when developing models of various phenomena, such as the production of the light elements.

Here, Poulin and Serpico show that, in some cases, this distribution of energy should be computed differently. They point to a previously known but often-overlooked exception to this spectral shape: when the energy of the colliding photon falls below a certain level, the spectral shape deviates from the normal predicted shape. This change could have many consequences, one of which concerns the lithium problem.

"More high-energy photons are present in the correctly computed spectrum than in the approximation typically used in the literature," Poulin said. "Such energetic photons are more effective in destroying lithium, making it easier for models to solve the disagreement while remaining consistent with other observations or constraints."

The scientists found that, in one simple and realistic scenario, the theory accurately predicts the observed amount of lithium (i.e., 1/3 of the current prediction), while at the same time satisfying all of the other BBN constraints and cosmological bounds that have plagued previous attempts.

How can higher-energy photons have such a large impact? The scientists explain that, in standard BBN, lithium is produced in a reaction in which the beryllium isotope 7Be decays into the lithium isotope 7Li. The beryllium originally comes from the fusion of two helium isotopes, a reaction that takes place in the thermal medium. When the photons in the thermal medium have higher energies, they favor the reverse reaction, resulting in more helium and less beryllium. With less beryllium, not as much lithium is produced as previously thought.

"A consequence of our results is that it is easier to solve the lithium problem in a broad class of new physics models, so to speak," Serpico said. "More in general, we would say that the importance of the lithium problem is due to its long-standing nature; it goes back to the beginning of the millennium and, despite several alternatives (both standard and exotic), none of them has been conclusively argued to be 'the one.' Concerning implications: If the solution is due to new physics, there will be profound implications for theories beyond the standard model as well as their impact on the early universe. Alternative classes of solutions may involve subtle aspects of stellar astrophysics, for instance. Hence, even more mundane explanations are typically not trivial at all."

In the future, the scientists plan to apply the results to other situations that may be affected by the loophole, and consider some of these cases even more urgent than the lithium problem.

"In particular, an obvious case is provided by big bang nucleosynthesis constraints on unstable relics, based on deuterium and helium measurements and for having a broader energy range (from a few MeV to hundreds of MeV)," they wrote. "This is a calculation we are currently completing.

"Of course, given its importance, we are also thinking about particle physics models that may 'exploit' the features we have pointed out, in order to provide a more efficient solution to the problem. Linking these results to the problem of the nature of dark matter or other signatures of particle physics beyond the standard model (for instance in the neutrino sector) is certainly on our medium-term agenda."

Explore further: Measurement at Big Bang conditions confirms lithium problem

More information: Vivian Poulin and Pasquale Dario Serpico. "Loophole to the Universal Photon Spectrum in Electromagnetic Cascades and Application to the Cosmological Lithium Problem." Physical Review Letters. DOI: 10.1103/PhysRevLett.114.091101

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23 comments

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KBK
1.2 / 5 (17) Mar 12, 2015
Poor sods will have to publicly acknowledge that transmutation does indeed take place, even in mundane daily life, and that we too can practice it in perfect simple repeatable scenarios....via resonant tickling, thermal addition, phononic excitation, etc, all as a combined system of manipulation.

That multiple scientists and inventors, over the past century (a minimum of dozens) have done these things, but have been buried and wiped out by special interests attempting to maintain dominance.

That this, as a problem, is peaking in the extreme ~~right now~~.

Hence the down-vote that this comment will receive by rubber stamp mouthpiece contributors, on this website's comment areas. It is as predictable as gravity.

sleep. sleep. sleep. Nothing to see here. Move along, stay in the fold.
Steve 200mph Cruiz
5 / 5 (21) Mar 12, 2015
Where's your solution KBK?

These researchers saw the same problem then offered a solution.
Why can't you contribute something?
Dethe
1.4 / 5 (12) Mar 12, 2015
according to the theory of big bang nucleosynthesis (BBN), isotopes of the three lightest elements—hydrogen, helium, and lithium—were created within the first 20 minutes after the big bang
This is indeed not the only problem of Big Bang model. The absence of lithium and another light elements has its dual counterpart in apparent redundancy of heavy elements (compare the frequent observations of mature galaxies with high metalicity at most distant areas of Universe). This is because according the steady state model the composition of Universe shouldn't depend on its perceived age and distance from Earth. Although it's possible to assume correction of Big Bang model with accelerated nucleosynthesis, the same assumption would make the absence of lithium even more problematical.
animah
5 / 5 (5) Mar 12, 2015
On a different note, good to see the Universite de Savoie in the news. Google images for "Annecy le Vieux", it's one of the most awesome towns in the world.
rufusgwarren
1 / 5 (12) Mar 12, 2015
Why use any of the big bang start with a random set of electrons and protons, use Maxwell for all motion, you can even program it without mass, since dq/dt is a current, it's all related. Try an infinite number of particles, the particle count never gets lower, energy is not lost by the electron or the proton, i.e. static state a constant always, no matter how you transform it. it appears as an infinite relative source for all frames. The wavelet produced by sudden motion shall create field events, we term photons and other "quirks". The particles will first cluster as elements based solely upon coulomb forces, i.e. iff close proximity then formation of neutrons, hydrogen, etc, etc.. However, the light elements require less pressure. So go figure, you can calculate what we think are those distances and required energy states.

What is the particle, an electron or a proton is unknown physics, lets not fool ourselves!
rufusgwarren
1 / 5 (11) Mar 12, 2015
The way I see it, the entire universe must be in steady state with these infinite sources, or the universe is still doing the job of creation! A light with an infinite source got turned on within an infinitely dark room, such is, each particle, and has been on for an infinite time; hence, on-switch unnecessary. For now, beyond our comprehension!
animah
5 / 5 (11) Mar 13, 2015
Rufus, that doesn't make any sense. If you want infinite space, you must necessarily have infinite time. But in an infinitely old universe, all stars have necessarily burned out. By the same token, the universe cannot be both steady state and observed to be expanding.
warmonger
5 / 5 (18) Mar 13, 2015
I would like to start a meme in which every scientific theory is met with the same stupid logic that climate deniers exhibit. Such as:

What?!? Scientists can't predict lithium levels? Clearly their models are completely bogus and they don't know what the hell they are talking about. Big bang? Yeah right. They can't even predict how a star forms in the first place, because they haven't seen it happen. These are just models. Just models people. How do they even know that there isn't enough lithium in the universe. It could be hiding in places they can't see. Maybe lithium levels go up and down and it's a natural trend. How long have they been measuring lithium content for? We don't know that their measurements are correct. They're just making stuff up to receive more grant money. Greedy, corrupt scientists.
Captain Stumpy
4.5 / 5 (15) Mar 13, 2015
What?!? Scientists can't predict lithium levels? Clearly their models are completely bogus and they don't know what the hell they are talking about. Big bang? Yeah right. They can't even predict how a star forms in the first place, because they haven't seen it happen. These are just models. Just models people. How do they even know that there isn't enough lithium in the universe. It could be hiding in places they can't see. Maybe lithium levels go up and down and it's a natural trend. How long have they been measuring lithium content for? We don't know that their measurements are correct. They're just making stuff up to receive more grant money. Greedy, corrupt scientists.
@warmonger
better make sure Zephir hasn't trademarked those arguments first, because he has/continues to use(d) a few of them himself!
ROTFLMFAO

at least you were poking fun... zeph, the eu et al actually believe that stuff!

you make a great point though
THANKS for the laugh
Dethe
1 / 5 (10) Mar 13, 2015
Scientists already know for thirty years, that the Big Bang model is unsustainable, but why to throw out the cow, which generates money? It's all just about salaries and job places. Nature is definitely more authoritative source for me than the opinion of anonymous trolls.
Torbjorn_Larsson_OM
4.6 / 5 (14) Mar 13, 2015
@Dethe: "the steady state model".

There is no "steady state model". All attempts to make one failed with the discovery of the cosmic microwave background.

"the Big Bang model is unsustainable".

And now you are just trolling. First sentence in an encyclopedia (with excellent references): "The Big Bang theory is the prevailing cosmological model ... ". [ http://en.wikiped...Big_Bang ]

If you have an alternative that cosmologists haven't already considered and rejected as inferior, let it predict the universe better than LCDM has. Note that with Planck's latest data release the tensions to the very few remaining anomalies (like BBN lithium) has lessened yet again. And now the above find that may predict the BBN lithium to everybody's satisfaction.
swordsman
not rated yet Mar 13, 2015
Attempting to correlate entropy with an atomic interaction event is nonsense.
Nanowill
1 / 5 (5) Mar 13, 2015
http://i.imgur.com/PPPaeiA.gif. It has been known for thirty years, that the Big Bang model is unsustainable, but why to throw out the cow, which generates money? It's all just about salaries and job places.

Agreed. The Big Bang Theory is completely incorrect, a relic of the religious notion of instant creation. This is provable but unfortunately dogma and periodical editors won't publish the proof, presumably for the reasons given above. The new theory also shows why there are no antiparticles in the Universe and offers a simple solution to the Dark Energy issue.
Just wish I could get it published someplace where real physicists might read it.
Dethe
1 / 5 (7) Mar 13, 2015
Agreed. The Big Bang Theory is completely incorrect, a relic of the religious notion of instant creation
We shouldn't make the same mistake again and overshoot the balanced view of reality with schematic thinking. The Big Bang model shares many similarities with geocentric model of solar system - it's indeed wrong from wider perspective, but still quite working from narrower one. In my understanding the Universe is random in essence, it just does look like the water surface at the small distance scales - but this surface isn't homogeneous. Unfortunately the scattering of ripples along it limits our scope of view, so we cannot fully recognize how inhomogeneous & random our Universe actually is at very large scales. We can just get a clue about it from Doppler CMBR anisotropy. This anisotropy is currently ignored, because it's believed to be an obstacle of Big Bang model - but in fact it does represent an indicia of Universe history at even wider scale.
FineStructureConstant
5 / 5 (6) Mar 14, 2015
@nano -
Just wish I could get it published someplace where real physicists might read it.
- ever heard of "the internet"?
Dethe
1 / 5 (5) Mar 14, 2015
There is no "steady state model". All attempts to make one failed with the discovery of the cosmic microwave background
There are actually many of them already. For example the cyclic universe or paralel multiuniverse concept or ekpyrotic cosmology are all based on much larger universe, than this one, which we can observe. And they get their support just from cosmic microwave background (1, 2).
Dethe
1 / 5 (6) Mar 14, 2015
the Big Bang model is unsustainable ... the Big Bang theory is the prevailing cosmological model
And what? All disproved scientific models were prevailing in some time of history.. If peer-reviewed Nature journal writes, that the Big Bang model is in decline, why the anonymous trolls (who otherwise argue with peer-review all the time) have so big problem with it?
rossim22
1.6 / 5 (7) Mar 14, 2015
""A consequence of our results is that it is easier to solve the lithium problem in a broad class of new physics models, so to speak," Serpico said."

This quote demonstrates the desperate grip on a severely flawed theory. A correct theory becomes more simple and cohesive with further observation, while the BB theory continues to require new realms of physics rather than admitting failure and investigating alternatives to an expanding universe.
Nik_2213
4.8 / 5 (5) Mar 14, 2015
Oh, wow ! IMHO, this is a very important finding. Hopefully, they can put better numbers to this curious, non-linear result.
warmonger
5 / 5 (6) Mar 15, 2015
@warmonger
better make sure Zephir hasn't trademarked those arguments first, because he has/continues to use(d) a few of them himself!
ROTFLMFAO

at least you were poking fun... zeph, the eu et al actually believe that stuff!

you make a great point though
THANKS for the laugh


I know. Even writing it I was worried people would think I was serious. That's how bad and predictable their logic is.
rpaul_bauman
2.3 / 5 (3) Mar 15, 2015
To understand Lithium, understand Be 9 and B 9. The change of ONE quark from - to + charge changes the isotope from stable to a half live of 10**-21 sec. The ONLY place this happens in 1500 different isotopes. That's because isotopes are structures, not some quantum fields. It also means that the decay rate of an isotope is from charge and has little to due with color. Li 3 thru 12 all use the same principle. Hope someone is interested.
PhotonX
3.7 / 5 (3) Mar 15, 2015
What?!? Scientists can't predict lithium levels? Clearly their models are completely bogus and they don't know what the hell they are talking about. Big bang? Yeah right. They can't even predict how a star forms in the first place, because they haven't seen it happen. These are just models. Just models people. How do they even know that there isn't enough lithium in the universe. It could be hiding in places they can't see. Maybe lithium levels go up and down and it's a natural trend. How long have they been measuring lithium content for? We don't know that their measurements are correct. They're just making stuff up to receive more grant money. Greedy, corrupt scientists.
rpaul_bauman
1 / 5 (1) Mar 17, 2015
So lets get this STRIGHT. There are 23 comments. Not one thinks the people that write science (physics) articles are doing a good job. Below, 2 comments down, is ONE star, the only one not with 5. So the commenters themselfs arn't doing a good job either. That's most likely every one if true. If there is a single word wrong in that comment, I would be happy if you would tell me. There is more physics in that single comment then 1000 papers. So kindly tell me , who is interested ?

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