Quotes & Sayings


We, and creation itself, actualize the possibilities of the God who sustains the world, towards becoming in the world in a fuller, more deeper way. - R.E. Slater

There is urgency in coming to see the world as a web of interrelated processes of which we are integral parts, so that all of our choices and actions have [consequential effects upon] the world around us. - Process Metaphysician Alfred North Whitehead

Kurt Gödel's Incompleteness Theorem says (i) all closed systems are unprovable within themselves and, that (ii) all open systems are rightly understood as incomplete. - R.E. Slater

The most true thing about you is what God has said to you in Christ, "You are My Beloved." - Tripp Fuller

The God among us is the God who refuses to be God without us, so great is God's Love. - Tripp Fuller

According to some Christian outlooks we were made for another world. Perhaps, rather, we were made for this world to recreate, reclaim, redeem, and renew unto God's future aspiration by the power of His Spirit. - R.E. Slater

Our eschatological ethos is to love. To stand with those who are oppressed. To stand against those who are oppressing. It is that simple. Love is our only calling and Christian Hope. - R.E. Slater

Secularization theory has been massively falsified. We don't live in an age of secularity. We live in an age of explosive, pervasive religiosity... an age of religious pluralism. - Peter L. Berger

Exploring the edge of life and faith in a post-everything world. - Todd Littleton

I don't need another reason to believe, your love is all around for me to see. – Anon

Thou art our need; and in giving us more of thyself thou givest us all. - Khalil Gibran, Prayer XXIII

Be careful what you pretend to be. You become what you pretend to be. - Kurt Vonnegut

Religious beliefs, far from being primary, are often shaped and adjusted by our social goals. - Jim Forest

We become who we are by what we believe and can justify. - R.E. Slater

People, even more than things, need to be restored, renewed, revived, reclaimed, and redeemed; never throw out anyone. – Anon

Certainly, God's love has made fools of us all. - R.E. Slater

An apocalyptic Christian faith doesn't wait for Jesus to come, but for Jesus to become in our midst. - R.E. Slater

Christian belief in God begins with the cross and resurrection of Jesus, not with rational apologetics. - Eberhard Jüngel, Jürgen Moltmann

Our knowledge of God is through the 'I-Thou' encounter, not in finding God at the end of a syllogism or argument. There is a grave danger in any Christian treatment of God as an object. The God of Jesus Christ and Scripture is irreducibly subject and never made as an object, a force, a power, or a principle that can be manipulated. - Emil Brunner

“Ehyeh Asher Ehyeh” means "I will be that who I have yet to become." - God (Ex 3.14) or, conversely, “I AM who I AM Becoming.”

Our job is to love others without stopping to inquire whether or not they are worthy. - Thomas Merton

The church is God's world-changing social experiment of bringing unlikes and differents to the Eucharist/Communion table to share life with one another as a new kind of family. When this happens, we show to the world what love, justice, peace, reconciliation, and life together is designed by God to be. The church is God's show-and-tell for the world to see how God wants us to live as a blended, global, polypluralistic family united with one will, by one Lord, and baptized by one Spirit. – Anon

The cross that is planted at the heart of the history of the world cannot be uprooted. - Jacques Ellul

The Unity in whose loving presence the universe unfolds is inside each person as a call to welcome the stranger, protect animals and the earth, respect the dignity of each person, think new thoughts, and help bring about ecological civilizations. - John Cobb & Farhan A. Shah

If you board the wrong train it is of no use running along the corridors of the train in the other direction. - Dietrich Bonhoeffer

God's justice is restorative rather than punitive; His discipline is merciful rather than punishing; His power is made perfect in weakness; and His grace is sufficient for all. – Anon

Our little [biblical] systems have their day; they have their day and cease to be. They are but broken lights of Thee, and Thou, O God art more than they. - Alfred Lord Tennyson

We can’t control God; God is uncontrollable. God can’t control us; God’s love is uncontrolling! - Thomas Jay Oord

Life in perspective but always in process... as we are relational beings in process to one another, so life events are in process in relation to each event... as God is to Self, is to world, is to us... like Father, like sons and daughters, like events... life in process yet always in perspective. - R.E. Slater

To promote societal transition to sustainable ways of living and a global society founded on a shared ethical framework which includes respect and care for the community of life, ecological integrity, universal human rights, respect for diversity, economic justice, democracy, and a culture of peace. - The Earth Charter Mission Statement

Christian humanism is the belief that human freedom, individual conscience, and unencumbered rational inquiry are compatible with the practice of Christianity or even intrinsic in its doctrine. It represents a philosophical union of Christian faith and classical humanist principles. - Scott Postma

It is never wise to have a self-appointed religious institution determine a nation's moral code. The opportunities for moral compromise and failure are high; the moral codes and creeds assuredly racist, discriminatory, or subjectively and religiously defined; and the pronouncement of inhumanitarian political objectives quite predictable. - R.E. Slater

God's love must both center and define the Christian faith and all religious or human faiths seeking human and ecological balance in worlds of subtraction, harm, tragedy, and evil. - R.E. Slater

In Whitehead’s process ontology, we can think of the experiential ground of reality as an eternal pulse whereby what is objectively public in one moment becomes subjectively prehended in the next, and whereby the subject that emerges from its feelings then perishes into public expression as an object (or “superject”) aiming for novelty. There is a rhythm of Being between object and subject, not an ontological division. This rhythm powers the creative growth of the universe from one occasion of experience to the next. This is the Whiteheadian mantra: “The many become one and are increased by one.” - Matthew Segall

Without Love there is no Truth. And True Truth is always Loving. There is no dichotomy between these terms but only seamless integration. This is the premier centering focus of a Processual Theology of Love. - R.E. Slater

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Note: Generally I do not respond to commentary. I may read the comments but wish to reserve my time to write (or write from the comments I read). Instead, I'd like to see our community help one another and in the helping encourage and exhort each of us towards Christian love in Christ Jesus our Lord and Savior. - re slater

Showing posts with label Online Science Courses. Show all posts
Showing posts with label Online Science Courses. Show all posts

Wednesday, October 13, 2021

Surprise: the Big Bang isn’t the beginning of the universe anymore


The modern cosmic picture of our universe’s history begins not with a singularity that we identify with the Big Bang, but rather with a period of cosmic inflation that stretches the universe to enormous scales, with uniform properties and spatial flatness. The end of inflation signifies the onset of the hot Big Bang. (Credit: Nicole Rager Fuller/National Science Foundation)


Surprise: the Big Bang isn’t the beginning
of the universe anymore

by Ethan Siegel
October 13, 2021


We used to think the Big Bang meant the universe began from
a singularity. Nearly 100 years later, we're not so sure.


Key Takeaways

  • The Big Bang teaches us that our expanding, cooling universe used to be younger, denser, and hotter in the past.
  • However, extrapolating all the way back to a singularity leads to predictions that disagree with what we observe.
  • Instead, cosmic inflation preceded and set up the Big Bang, changing our cosmic origin story forever.

Where did all this come from? In every direction we care to observe, we find stars, galaxies, clouds of gas and dust, tenuous plasmas, and radiation spanning the gamut of wavelengths: from radio to infrared to visible light to gamma rays. No matter where or how we look at the universe, it’s full of matter and energy absolutely everywhere and at all times. And yet, it’s only natural to assume that it all came from somewhere. If you want to know the answer to the biggest question of all — the question of our cosmic origins — you have to pose the question to the universe itself, and listen to what it tells you.

Today, the universe as we see it is expanding, rarifying (getting less dense), and cooling. Although it’s tempting to simply extrapolate forward in time, when things will be even larger, less dense, and cooler, the laws of physics allow us to extrapolate backward just as easily. Long ago, the universe was smaller, denser, and hotter. How far back can we take this extrapolation? Mathematically, it’s tempting to go as far as possible: all the way back to infinitesimal sizes and infinite densities and temperatures, or what we know as a singularity. This idea, of a singular beginning to space, time, and the universe, was long known as the Big Bang.

But physically, when we looked closely enough, we found that the universe told a different story. Here’s how we know the Big Bang isn’t the beginning of the universe anymore.

Countless scientific tests of Einstein’s general theory of relativity have been performed, subjecting the idea to some of the most stringent constraints ever obtained by humanity. Einstein’s first solution was for the weak-field limit around a single mass, like the Sun; he applied these results to our Solar System with dramatic success. Very quickly, a handful of exact solutions were found thereafter. (Credit: LIGO scientific collaboration, T. Pyle, Caltech/MIT)

Like most stories in science, the origin of the Big Bang has its roots in both theoretical and experimental/observational realms. On the theory side, Einstein put forth his general theory of relativity in 1915: a novel theory of gravity that sought to overthrow Newton’s theory of universal gravitation. Although Einstein’s theory was far more intricate and complicated, it wasn’t long before the first exact solutions were found.

  • In 1916, Karl Schwarzschild found the solution for a pointlike mass, which describes a nonrotating black hole.
  • In 1917, Willem de Sitter found the solution for an empty universe with a cosmological constant, which describes an exponentially expanding universe.
  • From 1916 to 1921, the Reissner-Nordström solution, found independently by four researchers, described the spacetime for a charged, spherically symmetric mass.
  • In 1921, Edward Kasner found a solution that described a matter-and-radiation-free universe that’s anisotropic: different in different directions.
  • In 1922, Alexander Friedmann discovered the solution for an isotropic (same in all directions) and homogeneous (same at all locations) universe, where any and all types of energy, including matter and radiation, were present.


An illustration of our cosmic history, from the Big Bang until the present, within the context of the expanding universe. The first Friedmann equation describes all of these epochs, from inflation to the Big Bang to the present and far into the future, perfectly accurately, even today. (Credit: NASA/WMAP science team)

That last one was very compelling for two reasons. One is that it appeared to describe our universe on the largest scales, where things appear similar, on average, everywhere and in all directions. And two, if you solved the governing equations for this solution — the Friedmann equations — you’d find that the universe it describes cannot be static, but must either expand or contract.

This latter fact was recognized by many, including Einstein, but it wasn’t taken particularly seriously until the observational evidence began to support it. In the 1910s, astronomer Vesto Slipher started observing certain nebulae, which some argued might be galaxies outside of our Milky Way, and found that they were moving fast: far faster than any other objects within our galaxy. Moreover, the majority of them were moving away from us, with fainter, smaller nebulae generally appearing to move faster.

Then, in the 1920s, Edwin Hubble began measuring individual stars in these nebulae and eventually determined the distances to them. Not only were they much farther away than anything else in the galaxy, but the ones at the greater distances were moving away faster than the closer ones. As Lemaître, Robertson, Hubble, and others swiftly put together, the universe was expanding.

Edwin Hubble’s original plot of galaxy distances versus redshift (left), establishing the expanding universe, versus a more modern counterpart from approximately 70 years later (right). In agreement with both observation and theory, the universe is expanding. (Credit: E. Hubble; R. Kirshner, PNAS, 2004)

Georges Lemaître was the first, in 1927, to recognize this. Upon discovering the expansion, he extrapolated backward, theorizing — as any competent mathematician might — that you could go as far back as you wanted: to what he called the primeval atom. In the beginning, he realized, the universe was a hot, dense, and rapidly expanding collection of matter and radiation, and everything around us emerged from this primordial state.

This idea was later developed by others to make a set of additional predictions:

  • The universe, as we see it today, is more evolved than it was in the past. The farther back we look in space, the farther back we’re also looking in time. So, the objects we see back then should be younger, less gravitationally clumpy, less massive, with fewer heavy elements, and with less-evolved structure. There should even be a point beyond which no stars or galaxies were present.
  • At some point, the radiation was so hot that neutral atoms couldn’t stably form, because radiation would reliably kick any electrons off of the nuclei they were attempting to bind to, and so there should be a leftover — now cold and sparse — bath of cosmic radiation from this time.
  • At some extremely early time it would have been so hot that even atomic nuclei would be blasted apart, implying there was an early, pre-stellar phase where nuclear fusion would have occurred: Big Bang nucleosynthesis. From that, we expect there to have been at least a population of light elements and their isotopes spread throughout the universe before any stars formed.

A visual history of the expanding universe includes the hot, dense state known as the Big Bang and the growth and formation of structure subsequently. The full suite of data, including the observations of the light elements and the cosmic microwave background, leaves only the Big Bang as a valid explanation for all we see. (Credit: NASA/CXC/M. Weiss)

In conjunction with the expanding universe, these four points would become the cornerstone of the Big Bang. The growth and evolution of the large-scale structure of the universe, of individual galaxies, and of the stellar populations found within those galaxies all validates the Big Bang’s predictions. The discovery of a bath of radiation just ~3 K above absolute zero — combined with its blackbody spectrum and temperature imperfections at microkelvin levels of tens to hundreds — was the key evidence that validated the Big Bang and eliminated many of its most popular alternatives. And the discovery and measurement of the light elements and their ratios — including hydrogen, deuterium, helium-3, helium-4, and lithium-7 — revealed not only which type of nuclear fusion occurred prior to the formation of stars, but also the total amount of normal matter that exists in the universe.

Extrapolating back to as far as your evidence can take you is a tremendous success for science. The physics that took place during the earliest stages of the hot Big Bang imprinted itself onto the universe, enabling us to test our models, theories, and understanding of the universe from that time. The earliest observable imprint, in fact, is the cosmic neutrino background, whose effects show up in both the cosmic microwave background (the Big Bang’s leftover radiation) and the universe’s large-scale structure. This neutrino background comes to us, remarkably, from just ~1 second into the hot Big Bang.

If there were no oscillations due to matter interacting with radiation in the universe, there would be no scale-dependent wiggles seen in galaxy clustering. The wiggles themselves, shown with the non-wiggly part subtracted out (bottom), is dependent on the impact of the cosmic neutrinos theorized to be present by the Big Bang. Standard Big Bang cosmology corresponds to β=1. (Credit: D. Baumann et al., Nature Physics, 2019)

But extrapolating beyond the limits of your measurable evidence is a dangerous, albeit tempting, game to play. After all, if we can trace the hot Big Bang back some 13.8 billion years, all the way to when the universe was less than 1 second old, what’s the harm in going all the way back just one additional second: to the singularity predicted to exist when the universe was 0 seconds old?

The answer, surprisingly, is that there’s a tremendous amount of harm — if you’re like me in considering “making unfounded, incorrect assumptions about reality” to be harmful. The reason this is problematic is because beginning at a singularity — at arbitrarily high temperatures, arbitrarily high densities, and arbitrarily small volumes — will have consequences for our universe that aren’t necessarily supported by observations.

For example, if the universe began from a singularity, then it must have sprung into existence with exactly the right balance of “stuff” in it — matter and energy combined — to precisely balance the expansion rate. If there were just a tiny bit more matter, the initially expanding universe would have already recollapsed by now. And if there were a tiny bit less, things would have expanded so quickly that the universe would be much larger than it is today.

If the universe had just a slightly higher density (red), it would have recollapsed already; if it had just a slightly lower density, it would have expanded much faster and become much larger. The Big Bang, on its own, offers no explanation as to why the initial expansion rate at the moment of the universe’s birth balances the total energy density so perfectly, leaving no room for spatial curvature at all. (Credit: Ned Wright’s cosmology tutorial)

And yet, instead, what we’re observing is that the universe’s initial expansion rate and the total amount of matter and energy within it balance as perfectly as we can measure.

Why?

If the Big Bang began from a singularity, we have no explanation; we simply have to assert “the universe was born this way,” or, as physicists ignorant of Lady Gaga call it, “initial conditions.”

Similarly, a universe that reached arbitrarily high temperatures would be expected to possess leftover high-energy relics, like magnetic monopoles, but we don’t observe any. The universe would also be expected to be different temperatures in regions that are causally disconnected from one another — i.e., are in opposite directions in space at our observational limits — and yet the universe is observed to have equal temperatures everywhere to 99.99%+ precision.

We’re always free to appeal to initial conditions as the explanation for anything, and say, “well, the universe was born this way, and that’s that.” But we’re always far more interested, as scientists, if we can come up with an explanation for the properties we observe.

In the top panel, our modern universe has the same properties (including temperature) everywhere because they originated from a region possessing the same properties. In the middle panel, the space that could have had any arbitrary curvature is inflated to the point where we cannot observe any curvature today, solving the flatness problem. And in the bottom panel, pre-existing high-energy relics are inflated away, providing a solution to the high-energy relic problem. This is how inflation solves the three great puzzles that the Big Bang cannot account for on its own. (Credit: E. Siegel/Beyond the Galaxy)

That’s precisely what cosmic inflation gives us, plus more. Inflation says, sure, extrapolate the hot Big Bang back to a very early, very hot, very dense, very uniform state, but stop yourself before you go all the way back to a singularity. If you want the universe to have the expansion rate and the total amount of matter and energy in it balance, you’ll need some way to set it up in that fashion. The same applies for a universe with the same temperatures everywhere. On a slightly different note, if you want to avoid high-energy relics, you need some way to both get rid of any preexisting ones, and then avoid creating new ones by forbidding your universe from getting too hot once again.

Inflation accomplishes this by postulating a period, prior to the hot Big Bang, where the universe was dominated by a large cosmological constant (or something that behaves similarly): the same solution found by de Sitter way back in 1917. This phase stretches the universe flat, gives it the same properties everywhere, gets rid of any pre-existing high-energy relics, and prevents us from generating new ones by capping the maximum temperature reached after inflation ends and the hot Big Bang ensues. Furthermore, by assuming there were quantum fluctuations generated and stretched across the universe during inflation, it makes new predictions for what types of imperfections the universe would begin with.

The quantum fluctuations that occur during inflation get stretched across the universe, and when inflation ends, they become density fluctuations. This leads, over time, to the large-scale structure in the universe today, as well as the fluctuations in temperature observed in the CMB. New predictions like these are essential for demonstrating the validity of a proposed fine-tuning mechanism. (Credit: E. Siegel; ESA/Planck and the DOE/NASA/NSF Interagency Task Force on CMB research)

Since it was hypothesized back in the 1980s, inflation has been tested in a variety of ways against the alternative: a universe that began from a singularity. When we stack up the scorecard, we find the following:

  • Inflation reproduces all of the successes of the hot Big Bang; there’s nothing that the hot Big Bang accounts for that inflation can’t also account for.
  • Inflation offers successful explanations for the puzzles that we simply have to say “initial conditions” for in the hot Big Bang.
  • Of the predictions where inflation and a hot Big Bang without inflation differ, four of them have been tested to sufficient precision to discriminate between the two. On those four fronts, inflation is 4-for-4, while the hot Big Bang is 0-for-4.

But things get really interesting if we look back at our idea of “the beginning.” Whereas a universe with matter and/or radiation — what we get with the hot Big Bang — can always be extrapolated back to a singularity, an inflationary universe cannot. Due to its exponential nature, even if you run the clock back an infinite amount of time, space will only approach infinitesimal sizes and infinite temperatures and densities; it will never reach it. This means, rather than inevitably leading to a singularity, inflation absolutely cannot get you to one by itself. The idea that “the universe began from a singularity, and that’s what the Big Bang was,” needed to be jettisoned the moment we recognized that an inflationary phase preceded the hot, dense, and matter-and-radiation-filled one we inhabit today.


Blue and red lines represent a “traditional” Big Bang scenario, where everything starts at time t=0, including spacetime itself. But in an inflationary scenario (yellow), we never reach a singularity, where space goes to a singular state; instead, it can only get arbitrarily small in the past, while time continues to go backwards forever. Only the last minuscule fraction of a second, from the end of inflation, imprints itself on our observable universe today. (Credit: E. Siegel)

This new picture gives us three important pieces of information about the beginning of the universe that run counter to the traditional story that most of us learned. First, the original notion of the hot Big Bang, where the universe emerged from an infinitely hot, dense, and small singularity — and has been expanding and cooling, full of matter and radiation ever since — is incorrect. The picture is still largely correct, but there’s a cutoff to how far back in time we can extrapolate it.

Second, observations have well established the state that occurred prior to the hot Big Bang: cosmic inflation. Before the hot Big Bang, the early universe underwent a phase of exponential growth, where any preexisting components to the universe were literally “inflated away.” When inflation ended, the universe reheated to a high, but not arbitrarily high, temperature, giving us the hot, dense, and expanding universe that grew into what we inhabit today.

Lastly, and perhaps most importantly, we can no longer speak with any sort of knowledge or confidence as to how — or even whether — the universe itself began. By the very nature of inflation, it wipes out any information that came before the final few moments: where it ended and gave rise to our hot Big Bang. Inflation could have gone on for an eternity, it could have been preceded by some other nonsingular phase, or it could have been preceded by a phase that did emerge from a singularity. Until the day comes where we discover how to extract more information from the universe than presently seems possible, we have no choice but to face our ignorance. The Big Bang still happened a very long time ago, but it wasn’t the beginning we once supposed it to be.


Tuesday, October 12, 2021

Richard Feynman - Armchair Discussions on Everything





“The highest forms of understanding we can achieve
are laughter and human compassion.”
― Richard P. Feynman



Great Minds: Richard Feynman - The Uncertainty Of Knowledge
Mar 4, 2010




“Nobody ever figures out what life is all about, and it doesn't matter.
Explore the world. Nearly everything is really interesting if you go
into it deeply enough.”― Richard P. Feynman



On religion
May 10, 2015




“For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled.”
― Richard P. Feynman



Richard Feynman. Why.
Apr 2, 2012




“I can live with doubt and uncertainty and not knowing. I think it is much more interesting to live not knowing than to have answers that might be wrong. If we will only allow that, as we progress, we remain unsure, we will leave opportunities for alternatives. We will not become enthusiastic for the fact, the knowledge, the absolute truth of the day, but remain always uncertain … In order to make progress, one must leave the door to the unknown ajar.” ― Richard P. Feynman



The best teacher I never had
Jan 27, 2016




“Study hard what interests you the most in the most
undisciplined, irreverent and original manner possible.”
― Richard P. Feynman



Feynman: Knowing versus Understanding
May 17, 2012




“We are trying to prove ourselves wrong as quickly as possible,
because only in that way can we find progress.”
― Richard P. Feynman



Richard Feynman - The World from another point of view
May 28, 2015




“Religion is a culture of faith; science is a culture of doubt.”
― Richard P. Feynman



On teaching
May 10, 2015




“Physics isn't the most important thing. Love is.”
― Richard P. Feynman



Richard Feynman on Pseudoscience
Apr 17, 2016




“The first principle is that you must not fool yourself
and you are the easiest person to fool.”
― Richard P. Feynman



Feynman - I Don't Like Honors [longer version]
Dec 2, 2006




“I would rather have questions that can't be answered
than answers that can't be questioned.”
― Richard P. Feynman



Richard Feynman talks about Algebra
Jan 22, 2014



“So I have just one wish for you – the good luck to be somewhere where you are free to maintain the kind of integrity I have described, and where you do not feel forced by a need to maintain your position in the organization, or financial support, or so on, to lose your integrity. May you have that freedom.” ― Richard P. Feynman Surely You're Joking, Mr. Feynman!: Adventures of a Curious Character

 


Feynman :: Rules of Chess
Feb 21, 2007




Richard Feynman talks about light
Nov 2, 2007




Richard Feynman Lecture - Los Alamos From Below
Jul 12, 2016




The complete FUN TO IMAGINE with Richard Feynman
Nov 1, 2018




“I learned very early the difference between knowing
the name of something and knowing something.”
― Richard P. Feynman



CNN, Feynman and the Challenger disaster
May 19, 2015









“You have no responsibility to live up to what other people think you ought to accomplish. I have no responsibility to be like they expect me to be. It's their mistake, not my failing.” ― Richard P. Feynman, Surely You're Joking, Mr. Feynman!: Adventures of a Curious Character

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“Physics is like sex: sure, it may give some practical results, but that's not why we do it.”
 Richard P. Feynman

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“I have a friend who's an artist and has sometimes taken a view which I don't agree with very well. He'll hold up a flower and say "look how beautiful it is," and I'll agree. Then he says "I as an artist can see how beautiful this is but you as a scientist take this all apart and it becomes a dull thing," and I think that he's kind of nutty. First of all, the beauty that he sees is available to other people and to me too, I believe. Although I may not be quite as refined aesthetically as he is ... I can appreciate the beauty of a flower. At the same time, I see much more about the flower than he sees. I could imagine the cells in there, the complicated actions inside, which also have a beauty. I mean it's not just beauty at this dimension, at one centimeter; there's also beauty at smaller dimensions, the inner structure, also the processes. The fact that the colors in the flower evolved in order to attract insects to pollinate it is interesting; it means that insects can see the color. It adds a question: does this aesthetic sense also exist in the lower forms? Why is it aesthetic? All kinds of interesting questions which the science knowledge only adds to the excitement, the mystery and the awe of a flower. It only adds. I don't understand how it subtracts.”  Richard P. Feynman, The Pleasure of Finding Things Out: The Best Short Works of Richard P. Feynman

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“Fall in love with some activity, and do it! Nobody ever figures out what life is all about, and it doesn't matter. Explore the world. Nearly everything is really interesting if you go into it deeply enough. Work as hard and as much as you want to on the things you like to do the best. Don't think about what you want to be, but what you want to do. Keep up some kind of a minimum with other things so that society doesn't stop you from doing anything at all.” ― Richard P. Feynman

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“I think it's much more interesting to live not knowing than to have answers which might be wrong. I have approximate answers and possible beliefs and different degrees of uncertainty about different things, but I am not absolutely sure of anything and there are many things I don't know anything about, such as whether it means anything to ask why we're here. I don't have to know an answer. I don't feel frightened not knowing things, by being lost in a mysterious universe without any purpose, which is the way it really is as far as I can tell.”  Richard P. Feynman

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“I'm smart enough to know that I'm dumb.”  Richard Feynman

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“I think it's much more interesting to live not knowing than to have answers which might be wrong.” Richard P. Feynman

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“If you thought that science was certain - well, that is just an error on your part.”
 Richard P. Feynman

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“You can know the name of a bird in all the languages of the world, but when you're finished, you'll know absolutely nothing whatever about the bird... So let's look at the bird and see what it's doing — that's what counts. I learned very early the difference between knowing the name of something and knowing something.”  Richard P. Feynman, "What Do You Care What Other People Think?": Further Adventures of a Curious Character

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“A poet once said, 'The whole universe is in a glass of wine.' We will probably never know in what sense he meant it, for poets do not write to be understood. But it is true that if we look at a glass of wine closely enough we see the entire universe. There are the things of physics: the twisting liquid which evaporates depending on the wind and weather, the reflection in the glass; and our imagination adds atoms. The glass is a distillation of the earth's rocks, and in its composition we see the secrets of the universe's age, and the evolution of stars. What strange array of chemicals are in the wine? How did they come to be? There are the ferments, the enzymes, the substrates, and the products. There in wine is found the great generalization; all life is fermentation. Nobody can discover the chemistry of wine without discovering, as did Louis Pasteur, the cause of much disease. How vivid is the claret, pressing its existence into the consciousness that watches it! If our small minds, for some convenience, divide this glass of wine, this universe, into parts -- physics, biology, geology, astronomy, psychology, and so on -- remember that nature does not know it! So let us put it all back together, not forgetting ultimately what it is for. Let it give us one more final pleasure; drink it and forget it all!”
 Richard P. Feynman

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“All the time you're saying to yourself, 'I could do that, but I won't,' — which is just another way of saying that you can't.”  Richard P. Feynman,  Surely You're Joking, Mr. Feynman!: Adventures of a Curious Character

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“What I am going to tell you about is what we teach our physics students in the third or fourth year of graduate school... It is my task to convince you not to turn away because you don't understand it. You see my physics students don't understand it... That is because I don't understand it. Nobody does.”  Richard P. Feynman,  QED: The Strange Theory of Light and Matter

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“Poets say science takes away from the beauty of the stars - mere globs of gas atoms. I too can see the stars on a desert night, and feel them. But do I see less or more? The vastness of the heavens stretches my imagination - stuck on this carousel my little eye can catch one - million - year - old light. A vast pattern - of which I am a part... What is the pattern, or the meaning, or the why? It does not do harm to the mystery to know a little about it. For far more marvelous is the truth than any artists of the past imagined it. Why do the poets of the present not speak of it? What men are poets who can speak of Jupiter if he were a man, but if he is an immense spinning sphere of methane and ammonia must be silent?”  Richard Feynman

---

“It doesn't seem to me that this fantastically marvelous universe, this tremendous range of time and space and different kinds of animals, and all the different planets, and all these atoms with all their motions, and so on, all this complicated thing can merely be a stage so that God can watch human beings struggle for good and evil - which is the view that religion has. The stage is too big for the drama.”  Richard P. Feynman

---

“There are 10^11 stars in the galaxy. That used to be a huge number. But it's only a hundred billion. It's less than the national deficit! We used to call them astronomical numbers. Now we should call them economical numbers.”  Richard Feynman

---

“I don't know what's the matter with people: they don't learn by understanding, they learn by some other way — by rote or something. Their knowledge is so fragile!”  Richard Feynman





Tuesday, May 25, 2021

Quantum Baryogenesis - Necessary Cosmic Asymmetry & Imbalance





In physical cosmology, baryogenesis is the generic term for hypothetical physical processes that produced an asymmetry between baryons and antibaryons in the very early universe, resulting in the substantial amounts of residual matter that make up the universe today. Baryogenesis theories employ sub-disciplines of physics such as quantum field theory, and statistical physics, to describe such possible mechanisms. The fundamental difference between baryogenesis theories is the description of the interactions between fundamental particles. The next step after baryogenesis is the much better understood Big Bang nucleosynthesis, during which light atomic nuclei began to form.





Classroom Aid - Baryogenesis



Antimatter and Matter : Baryogenesis



The Missing Mass Mystery | Space Time



FermiLab: What is Supersymmetry?



Astronomy: The Big Bang (18 of 30)
What is Baryogenesis?



Understanding very strong electroweak phase transitions
by Kimmo Kainulanen




Mikhail Shaposhnikov



Mikhail Shaposhnikov (EPFL Lausanne):
Baryogenesis and Leptogenesis - Lecture 1



Mikhail Shaposhnikov (EPFL Lausanne):
Baryogenesis and Leptogenesis - Lecture 2



Mikhail Shaposhnikov (EPFL Lausanne):
Baryogenesis and Leptogenesis - Lecture 3





RESOURCES

1 - Wikipedia - Dark Matter

2 - Wikipedia - Dark Energy

3 - https://www.sciencedirect.com/topics/physics-and-astronomy/baryogenesis

4 - https://deepblue.lib.umich.edu/bitstream/handle/2027.42/31589/0000518.pdf;sequence=1

5 - https://journals.aps.org/prd/abstract/10.1103/PhysRevD.103.043504

6 - https://www.sciencedirect.com/journal/physics-of-the-dark-universe/vol/32/suppl/C



* * * * * * * * * *


The Creation



And God stepped out on space,
And he looked around and said:
I'm lonely—
I'll make me a world.

And far as the eye of God could see
Darkness covered everything,
Blacker than a hundred midnights
Down in a cypress swamp.

Then God smiled,
And the light broke,
And the darkness rolled up on one side,
And the light stood shining on the other,
And God said: That's good!

Then God reached out and took the light in his hands,
And God rolled the light around in his hands
Until he made the sun;
And he set that sun a-blazing in the heavens.
And the light that was left from making the sun
God gathered it up in a shining ball
And flung it against the darkness,
Spangling the night with the moon and stars.
Then down between
The darkness and the light
He hurled the world;
And God said: That's good!

Then God himself stepped down—
And the sun was on his right hand,
And the moon was on his left;
The stars were clustered about his head,
And the earth was under his feet.
And God walked, and where he trod
His footsteps hollowed the valleys out
And bulged the mountains up.

Then he stopped and looked and saw
That the earth was hot and barren.
So God stepped over to the edge of the world
And he spat out the seven seas—
He batted his eyes, and the lightnings flashed—
He clapped his hands, and the thunders rolled—
And the waters above the earth came down,
The cooling waters came down.

Then the green grass sprouted,
And the little red flowers blossomed,
The pine tree pointed his finger to the sky,
And the oak spread out his arms,
The lakes cuddled down in the hollows of the ground,
And the rivers ran down to the sea;
And God smiled again,
And the rainbow appeared,
And curled itself around his shoulder.

Then God raised his arm and he waved his hand
Over the sea and over the land,
And he said: Bring forth! Bring forth!
And quicker than God could drop his hand,
Fishes and fowls
And beasts and birds
Swam the rivers and the seas,
Roamed the forests and the woods,
And split the air with their wings.
And God said: That's good!

Then God walked around,
And God looked around
On all that he had made.
He looked at his sun,
And he looked at his moon,
And he looked at his little stars;
He looked on his world
With all its living things,
And God said: I'm lonely still.

Then God sat down—
On the side of a hill where he could think;
By a deep, wide river he sat down;
With his head in his hands,
God thought and thought,
Till he thought: I'll make me a man!

Up from the bed of the river
God scooped the clay;
And by the bank of the river
He kneeled him down;
And there the great God Almighty
Who lit the sun and fixed it in the sky,
Who flung the stars to the most far corner of the night,
Who rounded the earth in the middle of his hand;
This great God,
Like a mammy bending over her baby,
Kneeled down in the dust
Toiling over a lump of clay
Till he shaped it in is his own image;

Then into it he blew the breath of life,
And man became a living soul.
Amen. Amen.

* * * * * * * * * *


Baryogenesis
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In physical cosmologybaryogenesis is the physical process that is hypothesized to have taken place during the early universe to produce baryonic asymmetry, i.e. the imbalance of matter (baryons) and antimatter (antibaryons) in the observed universe.[1]

One of the outstanding problems in modern physics is the predominance of matter over antimatter in the universe. The universe, as a whole, seems to have a nonzero positive baryon number density – that is, matter exists. Since it is assumed in cosmology that the particles we see were created using the same physics we measure today, it would normally be expected that the overall baryon number should be zero, as matter and antimatter should have been created in equal amounts. A number of theoretical mechanisms are proposed to account for this discrepancy, namely identifying conditions that favour symmetry breaking and the creation of normal matter (as opposed to antimatter). This imbalance has to be exceptionally small, on the order of 1 in every 1630000000 (~2×109) particles a small fraction of a second after the Big Bang.[2] After most of the matter and antimatter was annihilated, what remained was all the baryonic matter in the current universe, along with a much greater number of bosons. Experiments reported in 2010 at Fermilab, however, seem to show that this imbalance is much greater than previously assumed.[3] These experiments involved a series of particle collisions and found that the amount of generated matter was approximately 1% larger than the amount of generated antimatter. The reason for this discrepancy is yet unknown.

Most grand unified theories explicitly break the baryon number symmetry, which would account for this discrepancy, typically invoking reactions mediated by very massive X bosons (
X
)
 or massive Higgs bosons (
H0
).[4] The rate at which these events occur is governed largely by the mass of the intermediate 
X
 or 
H0
 particles, so by assuming these reactions are responsible for the majority of the baryon number seen today, a maximum mass can be calculated above which the rate would be too slow to explain the presence of matter today.[5] These estimates predict that a large volume of material will occasionally exhibit a spontaneous proton decay, which has not been observed. Therefore, the imbalance between matter and antimatter remains a mystery.

Baryogenesis theories are based on different descriptions of the interaction between fundamental particles. Two main theories are electroweak baryogenesis (standard model), which would occur during the electroweak epoch, and the GUT baryogenesis, which would occur during or shortly after the grand unification epochQuantum field theory and statistical physics are used to describe such possible mechanisms.

Baryogenesis is followed by primordial nucleosynthesis, when atomic nuclei began to form.

Background

The majority of ordinary matter in the universe is found in atomic nuclei, which are made of neutrons and protons. These nucleons are made up of smaller particles called quarks, and antimatter equivalents for each are predicted to exist by the Dirac equation in 1928.[6] Since then, each kind of antiquark has been experimentally verified. Hypotheses investigating the first few instants of the universe predict a composition with an almost equal number of quarks and antiquarks.[7] Once the universe expanded and cooled to a critical temperature of approximately 2×1012 K,[1] quarks combined into normal matter and antimatter and proceeded to annihilate up to the small initial asymmetry of about one part in five billion, leaving the matter around us.[1] Free and separate individual quarks and antiquarks have never been observed in experiments—quarks and antiquarks are always found in groups of three (baryons), or bound in quark–antiquark pairs (mesons). Likewise, there is no experimental evidence that there are any significant concentrations of antimatter in the observable universe.

There are two main interpretations for this disparity: either the universe began with a small preference for matter (total baryonic number of the universe different from zero), or the universe was originally perfectly symmetric, but somehow a set of phenomena contributed to a small imbalance in favour of matter over time. The second point of view is preferred, although there is no clear experimental evidence indicating either of them to be the correct one.

GUT Baryogenesis under Sakharov conditions

In 1967, Andrei Sakharov proposed[8] a set of three necessary conditions that a baryon-generating interaction must satisfy to produce matter and antimatter at different rates. These conditions were inspired by the recent discoveries of the cosmic background radiation[9] and CP-violation in the neutral kaon system.[10] The three necessary "Sakharov conditions" are:

Baryon number violation is a necessary condition to produce an excess of baryons over anti-baryons. But C-symmetry violation is also needed so that the interactions which produce more baryons than anti-baryons will not be counterbalanced by interactions which produce more anti-baryons than baryons. CP-symmetry violation is similarly required because otherwise equal numbers of left-handed baryons and right-handed anti-baryons would be produced, as well as equal numbers of left-handed anti-baryons and right-handed baryons. Finally, the interactions must be out of thermal equilibrium, since otherwise CPT symmetry would assure compensation between processes increasing and decreasing the baryon number.[11]

Currently, there is no experimental evidence of particle interactions where the conservation of baryon number is broken perturbatively: this would appear to suggest that all observed particle reactions have equal baryon number before and after. Mathematically, the commutator of the baryon number quantum operator with the (perturbative) Standard Model hamiltonian is zero: . However, the Standard Model is known to violate the conservation of baryon number only non-perturbatively: a global U(1) anomaly.[12] To account for baryon violation in baryogenesis, such events (including proton decay) can occur in Grand Unification Theories (GUTs) and supersymmetric (SUSY) models via hypothetical massive bosons such as the X boson.

The second condition – violation of CP-symmetry – was discovered in 1964 (direct CP-violation, that is violation of CP-symmetry in a decay process, was discovered later, in 1999).[13] Due to CPT symmetry, violation of CP-symmetry demands violation of time inversion symmetry, or T-symmetry.

In the out-of-equilibrium decay scenario,[14] the last condition states that the rate of a reaction which generates baryon-asymmetry must be less than the rate of expansion of the universe. In this situation the particles and their corresponding antiparticles do not achieve thermal equilibrium due to rapid expansion decreasing the occurrence of pair-annihilation.

Baryogenesis within the Standard Model

The Standard Model can incorporate baryogenesis, though the amount of net baryons (and leptons) thus created may not be sufficient to account for the present baryon asymmetry. There is a required one excess quark per billion quark-antiquark pairs in the early universe in order to provide all the observed matter in the universe.[1] This insufficiency has not yet been explained, theoretically or otherwise.

Baryogenesis within the Standard Model requires the electroweak symmetry breaking to be a first-order phase transition, since otherwise sphalerons wipe off any baryon asymmetry that happened up to the phase transition. Beyond this, the remaining amount of baryon non-conserving interactions is negligible.[15]

The phase transition domain wall breaks the P-symmetry spontaneously, allowing for CP-symmetry violating interactions to break C-symmetry on both its sides. Quarks tend to accumulate on the broken phase side of the domain wall, while anti-quarks tend to accumulate on its unbroken phase side.[11] Due to CP-symmetry violating electroweak interactions, some amplitudes involving quarks are not equal to the corresponding amplitudes involving anti-quarks, but rather have opposite phase (see CKM matrix and Kaon); since time reversal takes an amplitude to its complex conjugate, CPT-symmetry is conserved in this entire process.

Though some of their amplitudes have opposite phases, both quarks and anti-quarks have positive energy, and hence acquire the same phase as they move in space-time. This phase also depends on their mass, which is identical but depends both on flavor and on the Higgs VEV which changes along the domain wall.[16] Thus certain sums of amplitudes for quarks have different absolute values compared to those of anti-quarks. In all, quarks and anti-quarks may have different reflection and transmission probabilities through the domain wall, and it turns out that more quarks coming from the unbroken phase are transmitted compared to anti-quarks.

Thus there is a net baryonic flux through the domain wall. Due to sphaleron transitions, which are abundant in the unbroken phase, the net anti-baryonic content of the unbroken phase is wiped off as anti-baryons are transformed into leptons.[17] However, sphalerons are rare enough in the broken phase as not to wipe off the excess of baryons there. In total, there is net creation of baryons (as well as leptons).

In this scenario, non-perturbative electroweak interactions (i.e. the sphaleron) are responsible for the B-violation, the perturbative electroweak Lagrangian is responsible for the CP-violation, and the domain wall is responsible for the lack of thermal equilibrium and the P-violation; together with the CP-violation it also creates a C-violation in each of its sides.[18]

Matter content in the universe

The central question to Baryogenesis is what causes the preference for matter over antimatter in the universe, as well as the magnitude of this asymmetry. An important quantifier is the asymmetry parameter, given by

where nB and nB refer to the number density of baryons and antibaryons respectively and nγ is the number density of cosmic background radiation photons.[19]

According to the Big Bang model, matter decoupled from the cosmic background radiation (CBR) at a temperature of roughly 3000 kelvin, corresponding to an average kinetic energy of 3000 K / (10.08×103 K/eV) = 0.3 eV. After the decoupling, the total number of CBR photons remains constant. Therefore, due to space-time expansion, the photon density decreases. The photon density at equilibrium temperature T per cubic centimeter, is given by

,

with kB as the Boltzmann constantħ as the Planck constant divided by 2π and c as the speed of light in vacuum, and ζ(3) as Apéry's constant.[19] At the current CBR photon temperature of 2.725 K, this corresponds to a photon density nγ of around 411 CBR photons per cubic centimeter.

Therefore, the asymmetry parameter η, as defined above, is not the "best" parameter. Instead, the preferred asymmetry parameter uses the entropy density s,

because the entropy density of the universe remained reasonably constant throughout most of its evolution. The entropy density is

with p and ρ as the pressure and density from the energy density tensor Tμν, and g as the effective number of degrees of freedom for "massless" particles at temperature T (in so far as mc2 ≪ kBT holds),

,

for bosons and fermions with gi and gj degrees of freedom at temperatures Ti and Tj respectively. At the present epoch, s = 7.04 nγ.[19]

Ongoing research efforts

Ties to dark matter

A possible explanation for the cause of baryogenesis is the decay reaction of B-Mesogenesis. This phenomena suggests that in the early universe, particles such as the B-meson decay into a visible Standard Model baryon as well as a dark antibaryon that is invisible to current observation techniques.[20] The process begins by assuming a massive, long-lived, scalar particle  that exists in the early universe before Big Bang nucleosynthesis.[21] The exact behavior of  is as yet unknown, but it is assumed to decay into b quarks and antiquarks in conditions outside of thermal equilibrium, thus satisfying one Sakharov condition. These b quarks form into B-mesons, which immediately hadronize into oscillating CP-violating  states, thus satisfying another Sakharov condition.[22] These oscillating mesons then decay down into the baryon-dark antibaryon pair previously mentioned, , where  is the parent B-meson,  is the dark antibaryon,  is the visible baryon, and  is any extra light meson daughters required to satisfy other conservation laws in this particle decay.[20] If this process occurs fast enough, the CP-violation effect gets carried over to the dark matter sector. However, this contradicts (or at least challenges) the last Sakharov condition, since the expected matter preference in the visible universe is balanced by a new antimatter preference in the dark matter of the universe and total baryon number is conserved.[21]

B-Mesogenesis results in missing energy between the initial and final states of the decay process, which, if recorded, could provide experimental evidence for dark matter. Particle laboratories equipped with B-meson factories such as Belle and BaBar are extremely sensitive to B-meson decays involving missing energy and currently have the capability to detect the  channel.[23][24] The LHC is also capable of searching for this interaction since it produces several orders of magnitude more B-mesons than Belle or BaBar, but there are more challenges from the decreased control over B-meson initial energy in the accelerator.[20]

See also

References

Articles[edit]

  1. Jump up to:a b c d Liddle, Andrew (2015). An Introduction to Modern Cosmology(3rd ed.). Hoboken: Wiley. ISBN 978-1-118-69027-7OCLC 905985679.
  2. ^ Perez, Pavel Fileviez; Murgui, Clara; Plascencia, Alexis D. (2021-03-24). "Baryogenesis via Leptogenesis: Spontaneous B and L Violation"arXiv:2103.13397 [hep-ex, physics:hep-ph].
  3. ^ V.M. Abazov; et al. (2010). "Evidence for an anomalous like-sign dimuon charge asymmetry". Physical Review D82 (3): 032001. arXiv:1005.2757Bibcode:2010PhRvD..82c2001Adoi:10.1103/PhysRevD.82.032001PMID 20868090S2CID 10661879.
  4. ^ Ghosh, Avirup; Ghosh, Deep; Mukhopadhyay, Satyanarayan (2021-03-05). "The role of CP-conserving annihilations in generating cosmological particle-antiparticle asymmetries"arXiv:2103.03650 [astro-ph, physics:hep-ph].
  5. ^ Bass, Steven D.; De Roeck, Albert; Kado, Marumi (2021-04-14). "The Higgs boson -- its implications and prospects for future discoveries"arXiv:2104.06821 [hep-ex, physics:hep-ph].
  6. ^ P.A.M. Dirac (1928). "The Quantum Theory of the Electron"Proceedings of the Royal Society of London A117 (778): 610–624. Bibcode:1928RSPSA.117..610Ddoi:10.1098/rspa.1928.0023.
  7. ^ Sarkar, Utpal (2007). Particle and astroparticle physicsCRC Press. p. 429. ISBN 978-1-58488-931-1.
  8. ^ A. D. Sakharov (1967). "Violation of CP invariance, C asymmetry, and baryon asymmetry of the universe"Journal of Experimental and Theoretical Physics Letters5: 24–27. and in Russian, A. D. Sakharov(1967). "Violation of CP invariance, C asymmetry, and baryon asymmetry of the universe"ZhETF Pis'ma5: 32–35. republished as A. D. Sakharov (1991). "Violation of CP invariance, C asymmetry, and baryon asymmetry of the universe"Soviet Physics Uspekhi (in Russian and English). 34 (5): 392–393. Bibcode:1991SvPhU..34..392Sdoi:10.1070/PU1991v034n05ABEH002497.
  9. ^ A. A. PenziasR. W. Wilson (1965). "A Measurement of Excess Antenna Temperature at 4080 Mc/s". Astrophysical Journal142: 419–421. Bibcode:1965ApJ...142..419Pdoi:10.1086/148307.
  10. ^ J. W. CroninV. L. Fitch; et al. (1964). "Evidence for the 2π decay of the 
    K0
    2
     meson"
    Physical Review Letters13 (4): 138–140. Bibcode:1964PhRvL..13..138Cdoi:10.1103/PhysRevLett.13.138.
  11. Jump up to:a b M. E. Shaposhnikov; G. R. Farrar (1993). "Baryon Asymmetry of the Universe in the Minimal Standard Model". Physical Review Letters70 (19): 2833–2836. arXiv:hep-ph/9305274Bibcode:1993PhRvL..70.2833Fdoi:10.1103/PhysRevLett.70.2833PMID 10053665S2CID 15937666.
  12. ^ Boubakir, A.; Aissaoui, H.; Mebarki, N. (2021-02-18). "Strong First Order Phase Transition and $B$ Violation in the Compact 341 Model"arXiv:2102.09931 [hep-ph, physics:hep-th].
  13. ^ Griffiths, David J. (2008). Introduction to elementary particles (2nd ed.). Weinheim [Germany]: Wiley-VCH. ISBN 978-3-527-40601-2OCLC 248969635.
  14. ^ A. Riotto; M. Trodden (1999). "Recent progress in baryogenesis"Annual Review of Nuclear and Particle Science49: 46. arXiv:hep-ph/9901362Bibcode:1999ARNPS..49...35Rdoi:10.1146/annurev.nucl.49.1.35S2CID 10901646.
  15. ^ V. A. Kuzmin; V. A. Rubakov; M. E. Shaposhnikov (1985). "On anomalous electroweak baryon-number non-conservation in the early universe". Physics Letters B155 (1–2): 36–42. Bibcode:1985PhLB..155...36Kdoi:10.1016/0370-2693(85)91028-7.
  16. ^ Croon, Djuna; Howard, Jessica N.; Ipek, Seyda; Tait, Timothy M. P. (2020-03-31). "QCD Baryogenesis"Physical Review D101 (5): 055042. doi:10.1103/PhysRevD.101.055042ISSN 2470-0010.
  17. ^ Fujikura, Kohei; Harigaya, Keisuke; Nakai, Yuichiro; Wang, Ruoquan (2021-03-08). "Electroweak-like Baryogenesis with New Chiral Matter"arXiv:2103.05005 [astro-ph, physics:hep-ph].
  18. ^ Curtin, David; Jaiswal, Prerit; Meade, Patrick (2012-08-01). "Excluding electroweak baryogenesis in the MSSM"Journal of High Energy Physics2012 (8): 5. arXiv:1203.2932doi:10.1007/JHEP08(2012)005ISSN 1029-8479.
  19. Jump up to:a b c Cline, James M. (2006-11-22). "Baryogenesis"arXiv:hep-ph/0609145.
  20. Jump up to:a b c Alonso-Álvarez, Gonzalo; Elor, Gilly; Escudero, Miguel (2021-01-07). "Collider Signals of Baryogenesis and Dark Matter from $B$ Mesons: A Roadmap to Discovery"arXiv:2101.02706 [astro-ph, physics:hep-ex, physics:hep-ph].
  21. Jump up to:a b Elor, Gilly; Escudero, Miguel; Nelson, Ann E. (2019-02-20). "Baryogenesis and Dark Matter from $B$ Mesons"Physical Review D99 (3): 035031. doi:10.1103/PhysRevD.99.035031ISSN 2470-0010.
  22. ^ Particle Data Group; Tanabashi, M.; Hagiwara, K.; Hikasa, K.; Nakamura, K.; Sumino, Y.; Takahashi, F.; Tanaka, J.; Agashe, K.; Aielli, G.; Amsler, C. (2018-08-17). "Review of Particle Physics"Physical Review D98 (3): 030001. doi:10.1103/PhysRevD.98.030001.
  23. ^ BABAR Collaboration; Lees, J. P.; Poireau, V.; Tisserand, V.; Grauges, E.; Palano, A.; Eigen, G.; Stugu, B.; Brown, D. N.; Kerth, L. T.; Kolomensky, Yu. G. (2013-06-05). "Search for $B\ensuremath{\rightarrow}{K}^{\mathbf{(}*\mathbf{)}}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ and invisible quarkonium decays"Physical Review D87 (11): 112005. doi:10.1103/PhysRevD.87.112005.
  24. ^ Belle Collaboration; Lutz, O.; Neubauer, S.; Heck, M.; Kuhr, T.; Zupanc, A.; Adachi, I.; Aihara, H.; Asner, D. M.; Aushev, T.; Aziz, T. (2013-06-27). "Search for $B\ensuremath{\rightarrow}{h}^{(*)}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ with the full Belle $\ensuremath{\Upsilon}(4S)$ data sample"Physical Review D87 (11): 111103. doi:10.1103/PhysRevD.87.111103.

Textbooks[edit]

Preprints[edit]