Cosmology Archives

November 4, 2014December 23, 2015 by Tim Reyes

The World is Not Enough: A New Theory of Parallel Universes is Proposed

Do we exist in a space and time shared by many worlds? And are all these infinite worlds interacting? (Credit: Do-Da)

Imagine if you were told that the world is simple and exactly as it seems, but that there is an infinite number of worlds just like ours. They share the same space and time, and interact with each other. These worlds behave as Newton first envisioned, except that the slightest interactions of the infinite number create nuances and deviations from the Newtonian mechanics. What could be deterministic is swayed by many worlds to become the unpredictable.

This is the new theory about parallel universes explained by Australian and American theorists in a paper published in the journal Physics Review X. Called the “Many Interacting Worlds” theory (MIW), the paper explains that rather than standing apart, an infinite number of universes share the same space and time as ours. They show that their theory can explain quantum mechanical effects while leaving open the choice of theory to explain the universe at large scales. This is a fascinating new variant of Multiverse Theory that, in a sense, creates not just a doppelganger of everyone but an infinite number of them all overlaying each other in the same space and time.

Rather than island universes as proposed by other theories, Many Interacting Worlds (MIW) proposes many all lying within one space and time. (Photo Credit: Public Domain) — Rather than island universes as proposed by other multiverse theories, Many Interacting Worlds (MIW) proposes many all lying within one space and time.

Cosmology is a study in which practitioners must transcend their five senses. Einstein referred to thought experiments, and Dr. Stephen Hawking — surviving and persevering despite having ALS — has spent decades wondering about the Universe and developing new theories, all within his mind.

The “Many Interacting Worlds” theory, presented by Michael Hall and Howard Wiseman from Griffith University in Australia, and Dirk-André Deckert from the University of California, Davis, differs from previous multiverse theories in that the worlds — as they refer to universes — coincide with each other, and are not just parallel.

The theorists explain that while the interactions are subtle, the interaction of an infinite number of worlds can explain quantum phenomena such as barrier tunneling in solid state electronics, can be used to calculate quantum ground states, and, as they state, “at least qualitatively” reproduce the results of the double-slit experiment.

Schrödinger, in explaining his wave function and the interaction of two particles (EPR paradox) coined the term “entanglement”. In effect, the MIW theory is an entanglement of an infinite number of worlds but not in terms of a wave function. The theorists state that they were compelled to develop MIW theory to eliminate the need for a wave function to explain the Universe. It is quite likely that Einstein would have seen MIW as very appealing considering his unwillingness to accept the principles laid down by the Copenhagen interpretation of Quantum Theory.

While MIW theory can reproduce some of the most distinctive quantum phenomena, the theorists emphasize that MIW is in an early phase of development. They state that the theory is not yet as mature as long-standing unification theories. In their paper, they use Newtonian physics to keep their proofs simple. Presenting this new “many worlds” theory indicates they had achieved a level of confidence in its integrity such that other theorists can use it as a starter kit – peer review but also expand upon it to explain more worldly phenomena.

Hall compares MIW to the classical theory of ideal gases and partial pressures. He says:

Two worlds of many act as if they are two gases A & B within a volume of space. In the words of the theorists, “It would be as if the A gas and B gas were completely oblivious to each other unless every single A molecule were close to its B partner. Such an interaction is quite unlike anything in classical physics, and it is clear that our hypothetical A-composed observer would have no experience of the B world in its everyday observations, but by careful experiment might detect a subtle and nonlocal action on the A molecules of its world. Such action, though involving very many, rather than just two, worlds, is what we propose could lie behind the subtle and nonlocal character of quantum mechanics.”

Two of the perpetrators of the century long problem of unifying General Relativity Theory and Quantum Physics, A. Einstein, E. Schroedinger. — Two of the perpetrators of the century-long problem of unifying General Relativity Theory and Quantum Physics – Albert Einstein, Erwin Schroedinger.

The theorists continue by expounding that MIW could lead to new predictions. If correct, then new predictions would challenge experimentalists and observers to recreate or search for the effects. Such was the case for Einstein’s Theory of General Relativity. For example, the bending of the path of light by gravity and astronomer Eddington’s observing starlight bending around Sun during a total Solar Eclipse. Such new predictions and confirmation would begin to stand MIW theory apart from the many other theories of everything.

Hall, Deckert, and Wiseman continue – “Regarded as a fundamental physical theory in its own right, the MIW approach may also lead to new predictions arising from the restriction to a finite number of worlds. Finally, it provides a natural discretization of the Holland-Poirier approach, which may be useful for numerical purposes.”

Multiverse theories have gained notoriety in recent years through the books and media presentations of Dr. Michio Kaku of the City College of New York and Dr. Brian Greene of Columbia University, New York City. Dr. Green presented a series of episodes delving into the nature of the Universe on PBS called “The Fabric of the Universe” and “The Elegant Universe”. The presentations were based on his books such as “The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos.”

Hugh Everett’s reinterpretation of Dr. Richard Feynman’s cosmological theory, that the world is a weighted sum of alternative histories, states that when particles interact, reality bifurcates into a set of parallel streams, each being a different possible outcome. In contrast to Feynmann’s theory and Everett’s interpretation, the parallel worlds of MIW do not bifurcate but simply exist in the same space and time. MIW’s parallel worlds are not a consequence of “quantum behavior” but are rather the drivers of it.

Professor Howard Wiseman, Director of Griffith University's Centre for Quantum Dynamics and coauthor of the paper on the "Many Interacting World" theory. (Photo Credit: Griffith University) — Professor Howard Wiseman, Director of Griffith University’s Centre for Quantum Dynamics and coauthor of the paper on the “Many Interacting World” theory. (Photo Credit: Griffith University)

Hall states in the paper that simple Newtonian Physics can explain how all these worlds evolve. This, they explain, can be used effectively as a first approximation in testing and expanding on their theory, MIW. Certainly, Einstein’s Special and General Theories of Relativity completes the Newtonian equations and are not dismissed by MIW. However, the paper begins with the simpler model using Newtonian physics and even explains that some fundamental behavior of quantum mechanics unfolds from a universe comprised of just two interacting worlds.

So what is next for the Many Interacting Worlds theory? Time will tell. Theorists and experimentalists shall begin to evaluate its assertions and its solutions to explain known behavior in our Universe. With new predictions, the new challenger to Unified Field Theory (the theory of everything) will be harder to ignore or file away with the wide array of theories of the last 100 years. Einstein’s theories began to reveal that our world exudes behavior that defies our sensibility but he could not accept the assertions of Quantum Theory. Einstein’s retort to Bohr was “God does not throw dice.” The MIW theory of Hall, Deckert, and Wiseman might be what Einstein was seeking until the end of his life. For MIW theory, one world is not enough and for these many worlds their interactions might be compared to a martini shaken but not stirred.

References:

Quantum Phenomena Modeled by Interactions between Many Classical Worlds

September 24, 2014December 23, 2015 by Brian Koberlein

New Results from Planck: It Doesn’t Look Good For BICEP2

Dust map of the Universe. The region studied by BICEP2 is indicated by the rectangle in the right circle. Credit: Planck Collaboration

One of the recent sagas in cosmology began with the BICEP2 press conference announcing evidence of early cosmic inflation. There was some controversy since the press release was held before the paper was peer reviewed. The results were eventually published in Physical Review Letters, though with a more cautious conclusion than the original press release. Now the Planck team has released more of their data. This new work hasn’t yet been peer reviewed, but it doesn’t look good for BICEP2.

As you might recall, BICEP2 analyzed light from the cosmic microwave background (CMB) looking for a type of pattern known as B-mode polarization. This is a pattern of polarized light that (theoretically) is caused by gravitational waves produced by early cosmic inflation. There’s absolutely no doubt that BICEP2 detected B-mode polarization, but that’s only half the challenge. The other half is proving that the B-mode polarization they saw was due to cosmic inflation, and not due to some other process, mainly dust. And therein lies the problem. Dust is fairly common in the Milky Way, and it can also create B-mode polarization. Because the dust is between us and the CMB, it can contaminate its B-mode signal. This is sometimes referred to as the foreground problem. To really prove you have evidence of B-mode polarization in the CMB, you must ensure that you’ve eliminated any foreground effects from your data.

When the BICEP2 results were first announced, the question of dust was immediately raised. Some researchers noted that dust particles caught in magnetic fields could produce stronger B-mode effects than originally thought. Others pointed out that part of the data BICEP2 used to distinguish foreground dust wasn’t very accurate. This is part of the reason the final results went from “We found inflation!” to “We think we’ve found inflation! (But we can’t be certain.)”

Dust effects seen by Planck (shaded region) compared with inflation results of BICEP2 (solid line). Credit: Planck Collaboration — Dust effects seen by Planck (shaded region) compared with inflation results of BICEP2 (solid line).
Credit: Planck Collaboration

The new results from Planck chip at that claim even further. Whereas BICEP2 looked at a specific region of the sky, Planck has been gathering data across the entire sky. This means lots more data that can be used to distinguish foreground dust from a CMB signal. This new paper presented a map of the foreground dust, and a good summary can be seen in the figure. The shaded areas represents the B-mode levels due to dust at different scales. The solid line represents the B-mode distribution due to inflation as seen by BICEP2. As you can see, it matches the dust signal really well.

The simple conclusion is that the results of BICEP2 have been shown to be dust, but that isn’t quite accurate. It is possible that BICEP2 has found a mixture of dust and inflation signals, and with a better removal of foreground effects there may still be a real result. It is also possible that it’s all dust.

While this seems like bad news, it actually answers a mystery in the BICEP2 results. The level of inflation claimed by BICEP2 was actually quite large. Much larger than expected than many popular models. The fact that a good chuck of the B-mode polarization is due to dust means that inflation can’t be that large. So small inflation models are back in favor. It should also be emphasized that even if the BICEP2 results are shown to be entirely due to dust, that doesn’t mean inflation doesn’t exist. It would simply mean we have no evidence either way.

It’s tempting to look at all this with a bit of schadenfreude. Har, har, the scientists got it wrong again. But a more accurate view would be of two rival sports teams playing an excellent game. BICEP2 almost scored, but Planck rallied an excellent defense. Both teams want to be the first to score, but the other team won’t let them cheat to win. And we get to watch it happen.

Anyone who says science is boring hasn’t been paying attention.

Here’s the paper from the Planck team.

August 28, 2014December 23, 2015 by Shannon Hall

What Lit up the Universe? Astronomers May be on the Brink of an Answer

A computer model shows one scenario for how light is spread through the early universe on vast scales (more than 50 million light years across). Astronomers will soon know whether or not these kinds of computer models give an accurate portrayal of light in the real cosmos. Credit: Andrew Pontzen/Fabio Governato

Most scientists can see, hear, smell, touch or even taste their research. But astronomers can only study light — photons traveling billions of light-years across the cosmos before getting scooped up by an array of radio dishes or a single parabolic mirror orbiting the Earth.

Luckily the universe is overflowing with photons across a spectrum of energies and wavelengths. But astronomers don’t fully understand where most of the light, especially in the early universe, originates.

Now, new simulations hope to uncover the origin of the ultraviolet light that bathes — and shapes — the early cosmos.

“Which produces more light? A country’s biggest cities or its many tiny towns?” asked lead author Andrew Pontzen in a press release. “Cities are brighter, but towns are far more numerous. Understanding the balance would tell you something about the organization of the country. We’re posing a similar question about the universe: does ultraviolet light come from numerous but faint galaxies, or from a smaller number of quasars?”

Answering this question will give us a valuable insight into the way the universe built its galaxies over time. It will also help astronomers calibrate their measurements of dark energy, the mysterious agent that is somehow accelerating the universe’s expansion.

The problem is that most of intergalactic space is impossible to see directly. But quasars — brilliant galactic centers fueled by black holes rapidly accreting material — shine brightly and illuminate otherwise invisible matter. Any intervening gas will absorb the quasar’s light and leave dark lines in the arriving spectrum.

“Because they can be seen at such great distances, quasars are a useful probe for finding out the properties of the universe,” said Pontzen. “Distant quasars can be used as a backlight, and the properties of the gas between them and us are imprinted on the light.

Multiple clouds of intervening hydrogen gas leave a “forest” of hydrogen absorption lines in the quasar’s spectrum. But, crucially, not all gas in the universe contributes to these dark lines. When hydrogen is bombarded by ultraviolet light, it becomes ionized — the electron separates from the proton — which renders it transparent.

So the pattern of absorption lines visible in a quasar’s spectrum map out the location of neutral and ionized regions in between the quasar and the Earth.

This pattern will tell astronomers the main contributing light source in the early universe. Quasars are fairly limited in number but individually extremely bright. If they caused most of the radiation, the pattern will be far from uniform, with some areas nearly transparent and others strongly opaque. But if galaxies, which are far more numerous but much dimmer, caused most of the radiation, the pattern will be very uniform, with evenly spaced absorption lines.

Current samples of quasars aren’t quite big enough for a robust analysis of the subtle differences between the two scenarios. But Pontzen and colleagues show that a number of new surveys should shed light on the question.

The team is hopeful the DESI (Dark Energy Spectroscopic Instrument) survey, which will look at about a million distant quasars in order to better understand dark energy, will also show the distribution of intervening gas.

“It’s amazing how little is known about the objects that bathed the universe in ultraviolet radiation while galaxies assembled into their present form,” said coauthor Hiranya Peiris. “This technique gives us a novel handle on the intergalactic environment during this critical time in the Universe’s history.”

The paper was published Aug. 27 in the Astrophysical Journal Letters and is available online.

August 12, 2014December 23, 2015 by Shannon Hall

How did Supermassive Black Holes Grow so Massive so Quickly?

Artist concept of matter swirling around a black hole. (NASA/Dana Berry/SkyWorks Digital)

Black holes one billion times the Sun’s mass or more lie at the heart of many galaxies, driving their evolution. Although common today, evidence of supermassive black holes existing since the infancy of the Universe, one billion years or so after the Big Bang, has puzzled astronomers for years.

How could these giants have grown so massive in the relatively short amount of time they had to form? A new study led by Tal Alexander from the Weizmann Institute of Science and Priyamvada Natarajn from Yale University, may provide a solution.

Black holes are often mistaken to be monstrous creatures that suck in dust and gas at an enormous rate. But this couldn’t be further from the truth (in fact the words “suck” and “black hole” in the same sentence makes me cringe). Although they typically accumulate bright accretion disks — swirling disks of gas and dust that make them visible across the observable Universe — these very disks actually limit the speed of growth.

First, as matter in an accretion disk gets close to the black hole, traffic jams occur that slow down any other infalling material. Second, as matter collides within these traffic jams, it heats up, generating energy radiation that actually drives gas and dust away from the black hole.

A star or a gas stream can actually be on a stable orbit around the black hole, much as a planet orbits around a star. So it is quite a challenge for astronomers to think of ways that would make a black hole grow to supermassive proportions.

Luckily, Alexander and Natarajan may have found a way to do this: by placing the black hole within a cluster of thousands of stars, they’re able to operate without the restrictions of an accretion disk.

Black holes are generally thought to form when massive stars, weighing tens of solar masses, explode after their nuclear fuel is spent. Without the nuclear furnace at its core pushing against gravity, the star collapses. While the inner layers fall inward to form a black hole of only about 10 solar masses, the outer layers fall faster, hitting the inner layers, and rebounding in a huge supernova explosion. At least that’s the simple version.

A small black hole gains mass: Dense cold gas (green) flows toward the center of a stellar cluster (red cross in blue circle) with stars (yellow); the erratic path of the black hole through the gas (black line) is randomized by the surrounding stars Prof. Tal Alexander’s research is supported by the European Research Council. — The erratic path of the black hole through the gas (black line) is randomized by the surrounding stars (yellow circles). Meanwhile, dense cold gas (green arrows) flows toward the center of the cluster (red cross). Credit: Weizmann Institute of Science.

The team began with a model of a black hole, created from this stellar blast, embedded within a cluster of thousands of stars. A continuous flow of dense, cold, opaque gas fell into the black hole. But here’s the trick: the gravitational pull of many nearby stars caused it to zigzag randomly, preventing it from forming an accretion disk.

Without an accretion disk, not only is matter more able to fall into the black hole from all sides, but it isn’t slowed down in the accretion disk itself.

All in all, the model suggests that a black hole 10 times the mass of the Sun could grow to more than 10 billion times the mass of the Sun by one billion years after the Big Bang.

The paper was published Aug. 7 in Science and is available online.

June 26, 2014December 23, 2015 by Tim Reyes

Has the Cosmology Standard Model become a Rube Goldberg Device?

Artists illustration of the expansion of the Universe (Credit: NASA, Goddard Space Flight Center)

This week at the Royal Astronomical Society’s National Astronomy Meeting in the UK, physicists are challenging the evidence for the recent BICEP2 results regarding the inflation period of the Universe, announced just 90 days ago. New research is laying doubt upon the inclusion of inflation theory in the Standard Cosmological Model for understanding the forces of nature, the nature of elementary particles and the present state of the known Universe.

Back on March 17, 2014, it seemed the World was offered a glimpse of an ultimate order from eons ago … actually from the beginning of time. BICEP2, the single purpose machine at the South Pole delivered an image that after analysis, and subtraction of estimated background signal from the Milky Way, lead its researchers to conclude that they had found the earliest remnant from the birth of the Universe, a signature in ancient light that supported the theory of Inflation.

BICEP2 Telescope at twilight at the South Pole, Antartica (Credit: Steffen Richter, Harvard University) — BICEP2 Telescope at twilight at the South Pole, Antarctica (Credit: Steffen Richter, Harvard University)

Thirty years ago, the Inflation theory was conceived by physicists Alan Guth and Andei Linde. Guth, Linde and others realized that a sudden expansion of the Universe at only 1/1000000000000000000000000000000000th of a second after the Big Bang could solve some puzzling mysteries of the Cosmos. Inflation could explain the uniformity of the cosmic background radiation. While images such as from the COBE satellite show a blotchy distribution of radiation, in actuality, these images accentuate extremely small variations in the background radiation, remnants from the Big Bang, variations on the order of 1/100,000th of the background level.

Note that the time of the Universe’s proposed Inflationary period immediately after the Big Bang would today permit light to travel only 1/1000000000000000th of the diameter of the Hydrogen atom. The Universe during this first moment of expansion was encapsulated in a volume far smaller than the a single atom.

Emotions ran very high when the BICEP2 team announced their findings on March 17 of this year. The inflation event that the background radiation data supported is described as a supercooling of the Cosmos however, there were physicists that simply remained cool and remained contrarians to the theory. Noted British Physicist Sir Roger Primrose was one who remained underwhelmed and stated that the incredible circular polarization of light that remained in the processed data from BICEP2 could be explained by the interaction of dust, light and magnetic fields in our own neighborhood, the Milky Way.

Illustration of the ESA Planck Telescope in Earth orbit (Credit: ESA)

Now, new observations from another detector, one on the Planck Satellite orbiting the Earth, is revealing that the contribution of background radiation from local sources, the dust in the Milky Way, is appearing to have been under-estimated by the BICEP2 team. All the evidence is not yet laid out but the researchers are now showing reservations. At the same time, it does not dismiss the Inflation Theory. It means that more observations are needed and probably with greater sensitivity.

So why ask the question, are physicists constructing a Rube Goldberg device?

Our present understanding of the Universe stands upon what is called “the Standard Model” of Cosmology. At the Royal Astronomical Society meeting this week, the discussions underfoot could be revealing a Standard Model possibly in a state of collapse or simply needing new gadgets and mechanisms to remain the best theory of everything.

Also this week, new data further supports the discovery of the Higg’s Boson by the Large Hadron Collider in 2012, the elementary particle whose existence explains the mass of fundamental particles in nature and that supports the existence of the Higgs Field vital to robustness of the Standard Model. However, the Higgs related data is also revealing that if the inflationary period of the Universe did take place, then if taken with the Standard Model, one can conclude that the Universe should have collapsed upon itself and our very existence today would not be possible.

A Rube Goldberg Toothpaste dispenser as also the state of the Standard Model (Credit: R.Goldberg)

Dr. Brian Green, a researcher in the field of Super String Theory and M-Theory and others such as Dr. Stephen Hawking, are quick to state that the Standard Model is an intermediary step towards a Grand Unified Theory of everything, the Universe. The contortion of the Standard Model, into a sort of Rube Goldberg device can be explained by the undaunting accumulation of more acute and diverse observations at cosmic and quantum scales.

Discussions at the Royal Astronomical Society meeting are laying more doubts upon the inflation theory which just 90 days ago appeared so well supported by BICEP2 – data derived by truly remarkable cutting edge electronics developed by NASA and researchers at the California Institute of Technology. The trials and tribulations of these great theories to explain everything harken back to the period just prior to Einstein’s Miracle Year, 1905. Fragmented theories explaining separately the forces of nature were present but also the accumulation of observational data had reached a flash point.

Today, observations from BICEP2, NASA and ESA great space observatories, sensitive instruments buried miles underground and carefully contrived quantum experiments in laboratories are making the Standard Model more stressed in explaining everything, the same model so well supported by the Higg’s Boson discovery just two years ago. Cosmologists concede that we may never have a complete, proven theory of everything, one that is elegant; however, the challenges upon the Standard Model and inflation will surely embolden younger theorists to double the efforts in other theoretical work.

For further reading:
RAS NAM press release: Should the Higgs Boson Have Caused our Universe To Collapse?
We’ve Discovered Inflation!: Now What?
Cosmologists Cast Doubt on Inflation Evidence
Are the BICEP2 Results Invalid? Probably Not

May 19, 2014December 23, 2015 by Brian Koberlein

Are the BICEP2 Results Invalid? Probably Not.

Galactic radio loops, with BICEP2 region indicated. Credit: Philipp Mertsch

Recently rumors have been flying that the BICEP2 results regarding the cosmic inflationary period may be invalid. It all started with a post by Dan Falkowski on his blog Resonaances, where he claimed that the BICEP2 had misinterpreted some data, which rendered their results invalid, or at least questionable. The story was then picked up by Nature’s Blog and elsewhere, which has sparked some heated debate.

So what’s really going on?

For those who might not remember, BICEP2 is a project working to detect polarized light within the cosmic microwave background (CMB). Specifically they were looking for a type of polarization known as B-mode polarization. Detection of B-mode polarization is important because one mechanism for it is cosmic inflation in the early universe, which is exactly what BICEP2 claimed to have evidence of.

Part of the reason BICEP2 got so much press is because B-mode polarization is particularly difficult to detect. It is a small signal, and you have to filter through a great deal of observational data to be sure that your result is valid. But you also have to worry about other sources that look like B-mode polarization, and if you don’t account for them properly, then you could get a “false positive.” That’s where this latest drama arises.

In general this challenge is sometimes called the foreground problem. Basically, the cosmic microwave background is the most distant light we can observe. All the galaxies, dust, interstellar plasma and our own galaxy is between us and the CMB. So to make sure that the data you gather is really from the CMB, you have to account for all the stuff in the way (the foreground). We have ways of doing this, but it is difficult. The big challenge is to account for everything.

A map of foreground polarization from the Milky Way. Credit: ESA and the Planck Collaboration

Soon after the BICEP2 results, another team noted a foreground effect that could effect the BICEP2 results. It involves an effect known as radio loops, where dust particles trapped in interstellar magnetic fields can emit polarized light similar to B-mode polarization. How much of an effect this might have is unclear. Another project being done with the Planck satellite is also looking at this foreground effect, and has released some initial results (seen in the figure), but hasn’t yet released the actual data yet.

Now it has come to light that BICEP2 did, in fact, take some of this foreground polarization into account, in part using results from Planck. But since the raw data hadn’t been released, the team used data taken from a PDF slide of Planck results and basically reverse-engineered the Planck data. It is sometimes referred to as “data scraping”, and it isn’t ideal, but it works moderately well. Now there is some debate as to whether that slide presented the real foreground polarization or some averaged polarization. If it is the latter, then the BICEP2 results may have underestimated the foreground effect. Does this mean the BICEP2 results are completely invalid? Given what I’ve seen so far, I don’t think it does. Keep in mind that the Planck foreground is one of several foreground effects that BICEP2 did account for. It could be a large error, but it could also be a rather minor one.

The important thing to keep in mind is that the BICEP2 paper is still undergoing peer review. Critical analysis of the paper is exactly what should happen, and is happening. This type review used to be confined to the ivory towers, but with social media it now happens in the open. This is how science is done. BICEP2 has made a bold claim, and now everyone gets to whack at them like a piñata.

The BICEP2 team stands by their work, and so we’ll have to see whether it holds up to peer review. We’ll also have to wait for the Planck team to release their results on B-mode polarization. Eventually the dust will settle and we’ll have a much better handle on the results.

May 4, 2014December 23, 2015 by Shannon Hall

“Fossil Galaxy” Discovered From the Early Universe

According to new research, life as we know it might have emerged earlier than other intelligent life. Credit: ESO

A small galaxy circling the Milky Way may be a fossil left over from the early Universe.

The stars in the galaxy, known as Segue 1, are virtually pure with fewer heavy elements than those of any other galaxy known. Such few stars (roughly 1,000 compared to the Milky Way’s 100 billion) with such small amounts of heavy elements imply the dwarf galaxy may have stopped evolving almost 13 billion years ago.

If true, Segue 1 could offer a window into the early universe, revealing new evolutionary pathways among galaxies in the early Universe.

Only hydrogen, helium, and a small trace of lithium emerged from the Big Bang nearly 13.8 billion years ago, leaving a young universe that was virtually pure. Over time the cycle of star birth and death produced and dispersed more heavy elements (often referred to as “metals” in astronomical circles), planting the seeds necessary for rocky planets and intelligent life.

The older a star is, the less contaminated it was at birth, and the fewer metals lacing the star’s surface today. Thus the elements detectible in a star’s spectrum provide a key to understanding the generations of stars, which preceded the star’s birth.

The Sun, for example, is metal-rich, with roughly 1.4% of its mass composed of elements heavier than hydrogen and helium. It formed only 4.6 billion years ago — two thirds of the way from the Big Bang to now — and sprung from multiple generations of earlier stars.

But three stars visible in Segue 1 have an iron abundance that is roughly 3,000 times less than the Sun’s iron. Or to use the proper jargon, these three stars have metallicities below [Fe/H] = -3.5.

Researchers led by Anna Frebel of the Massachusetts Institute of Technology report that Segue 1 “may be a surviving first galaxy that experienced only one burst of star formation” in the Astrophysical Journal.

Not only do the low chemical abundances suggest this galaxy is composed of extremely old stars, but they provide tantalizing hints about the types of supernovae explosions that helped create these stars. When high-mass stars explode they disperse a mix of elements; But when low-mass stars explode they almost exclusively disperse iron.

The lack of iron suggests the stars in Segue 1 are the products of high mass stars, which explode much more quickly than low mass stars. It appears that Segue 1 underwent a rapid burst of star formation shortly after the formation of the galaxy in the early universe.

Additionally, six stars observed show some of the lowest levels of neutron-capture elements ever found, with roughly 16,000 fewer elements than those seen in the Sun. These elements are created within stars when an atomic nucleus grabs an extra neutron. So a low level indicates a lack of repeated star formation.

Segue 1 burned through its first generation of stars quickly. But after the young galaxy produced a second generation of stars it completely shut off star formation, remaining a relic of the early universe.

The findings here suggest there may be a greater diversity of evolutionary pathways among galaxies in the early universe than had previously been thought.

But before we can make any sweeping claims “we really need to find more of these systems,” said Frebel in a press release. Alternatively, “if we never find another one, it would tell us how rare it is that galaxies fail in their evolution. We just don’t know at this stage because this is the first of its kind.”

The paper will be published in the Astrophysical Journal and is available for download here.

April 18, 2014December 23, 2015 by Nancy Atkinson

Watch Live Webcast: Secrets of the Universe’s First Light

The BICEP telescope located at the south pole. Image Credit: CfA / Harvard

Just a month ago came the news of the first direct evidence of primordial gravitational waves — ripples in the fabric of spacetime — providing the first direct evidence the Universe underwent a brief but stupendously accelerated expansion immediately following the Big Bang.

This almost unimaginably fast expansion when the Universe was only a trillionth of a trillionth of a trillionth of a second was first theorized more than three decades ago, and the announcement last month was so monumental that some are comparing it to the discovery of the Higgs boson.

On April 18, 20:00 UTC (3 pm EDT, 1:00 pm PDT, two of the scientists who made this groundbreaking discovery will come together for a conversation with two of the pioneering leaders of the field. Together, they will examine the detection of a distinctive, swirling pattern in the universe’s first light, what the swirl tells us about that monumental growth spurt, and the many implications on the way we understand the universe around us.

You can watch below:

The hangout will include members of the BICEP2, which made the discovery, as well as two notable scientists in this field, John Carlstrom and Michael Turner.

March 24, 2014December 23, 2015 by Jason Major

Cosmologists Cast Doubt on Inflation Evidence

Some physicists still have questions on the true origin of the BICEP2 findings...

It was just a week ago that the news blew through the scientific world like a storm: researchers from the BICEP2 project at the South Pole Telescope had detected unambiguous evidence of primordial gravitational waves in the cosmic microwave background, the residual rippling of space and time created by the sudden inflation of the Universe less than a billionth of a billionth of a second after the Big Bang. With whispers of Nobel nominations quickly rising in the science news wings, the team’s findings were hailed as the best direct evidence yet of cosmic inflation, possibly even supporting the existence of a multitude of other universes besides our own.

That is, if they really do indicate what they appear to. Some theorists are advising that we “put the champagne back in the fridge”… at least for now.

Theoretical physicists and cosmologists James Dent, Lawrence Krauss, and Harsh Mathur have submitted a brief paper (arXiv:1403.5166 [astro-ph.CO]) stating that, while groundbreaking, the BICEP2 Collaboration findings have yet to rule out all possible non-inflation sources of the observed B-mode polarization patterns and the “surprisingly large value of r, the ratio of power in tensor modes to scalar density perturbations.”

“However, while there is little doubt that inflation at the Grand Unified Scale is the best motivated source of such primordial waves, it is important to demonstrate that other possible sources cannot account for the current BICEP2 data before definitely claiming Inflation has been proved. “

– Dent, Krauss, and Mathur (arXiv:1403.5166 [astro-ph.CO])

The history of the universe starting the with the Big Bang. Image credit: grandunificationtheory.com

Inflation may very well be the cause — and Dent and company state right off the bat that “there is little doubt that inflation at the Grand Unified Scale is the best motivated source of such primordial waves” — but there’s also a possibility, however remote, that some other, later cosmic event is responsible for at least some if not all of the BICEP2 measurements. (Hence the name of the paper: “Killing the Straw Man: Does BICEP Prove Inflation?”)

Not intending to entirely rain out the celebration, Dent, Krauss, and Mathur do laud the BICEP2 findings as invaluable to physics, stating that they “will be very important for constraining physics beyond the standard model, whether or not inflation is responsible for the entire BICEP2 signal, even though existing data from cosmology is strongly suggestive that it does.”

Now I’m no physicist, cosmologist, or astronomer. Actually I barely passed high school algebra (and I have the transcripts to prove it) so if you want to get into the finer details of this particular argument I invite you to read the team’s paper for yourself here and check out a complementary article on The Physics arXiv Blog.

And so, for better or worse (just kidding — it’s definitely better) this is how science works and how science is supposed to work. A claim is presented, and, regardless of how attractive its implications may be, it must stand up to any other possibilities before deemed the decisive winner. It’s not a popularity contest, it’s not a beauty contest, and it’s not up for vote. What it is up for is scrutiny, and this is just an example of scientists behaving as they should.

Still, I’d keep that champagne nicely chilled.

Source: The Physics arXiv Blog

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Want to read more about the BICEP2 findings from actual physicists? Read more in an article by Peter Coles, see what Matthew Francis has to say in his article on arstechnica here, and watch a video by Sean Carroll on PBS News Hour.

March 17, 2014April 26, 2016 by Brian Koberlein

We’ve Discovered Inflation! Now What?

Polarization patterns imprinted in the CMB. Image Credit: CfA

Days like these make being an astrophysicist interesting. On the one hand, there is the annoucement of BICEP2 that the long-suspected theory of an inflationary big bang is actually true. It’s the type of discovery that makes you want to grab random people off the street and tell them what an amazing thing the Universe is. On the other hand, this is exactly the type of moment when we should be calm, and push back on the claims made by one research team. So let’s take a deep breath and look at what we know, and what we don’t.

Multiverse Theory — Inflation could mean our Universe is just one of many. Credit: Florida State University

First off, let’s dispel a few rumors. This latest research is not the first evidence of gravitational waves. The first indirect evidence for gravitational waves was found in the orbital decay of a binary pulsar by Russell Hulse and Joseph Taylor, for which they were awarded the Nobel prize in 1993. This new work is also not the first discovery of polarization within the cosmic microwave background, or even the first observation of B-mode polarization. This new work is exciting because it finds evidence of a specific form of B-mode polarization due to primordial gravitational waves. The type of gravitational waves that would only be caused by inflation during the earliest moments of the Universe.

It should also be noted that this new work hasn’t yet been peer reviewed. It will be, and it will most likely pass muster, but until it does we should be a bit cautious about the results. Even then these results will need to be verified by other experiments. For example, data from the Planck space telescope should be able to confirm these results assuming they’re valid.

That said, these new results are really, really interesting.

E-modes (left side) — E-modes (left) and B-modes (right)

What the team did was to analyze what is known as B-mode polarization within the cosmic microwave background (CMB). Light waves oscillate perpendicular to their direction of motion, similar to the way water waves oscillate up and down while they travel along the surface of water. This means light can have an orientation. For light from the CMB, this orientation has two modes, known as E and B. The E-mode polarization is caused by temperature fluctuations in the CMB, and was first observed in 2002 by the DASI interferometer.

The B-mode polarization can occur in two ways. The first way is due to gravitational lensing. The first is due to gravitational lensing of the E-mode. The cosmic microwave background we see today has travelled for more than 13 billion years before reaching us. Along its journey some of it has passed close enough to galaxies and the like to be gravitationally lensed. This gravitational lensing twists the polarization a bit, giving some of it a B-mode polarization. This type was first observed in July of 2013. The second way is due to gravitational waves from the early inflationary period of the universe. As inflationary period occurred, then it produced gravitational waves on a cosmic scale. Just as the gravitational lensing produces B-mode polarization, these primordial gravitational waves produce a B-mode effect. The discovery of primordial wave B-mode polarization is what was announced today.

The effect of early inflation on the size of the universe. Credit: NASA/COBE

Inflation has been proposed as a reason for why the cosmic microwave background is as uniform as it is. We see small fluctuations in the CMB, but not large hot or cold spots. This means the early Universe must have been small enough for temperatures to even out. But the CMB is so uniform that the observable universe must have been much smaller than predicted by the big bang. However, if the Universe experienced a rapid increase in size during its early moments, then everything would work out. The only problem was we didn’t have any direct evidence of inflation.

Assuming these new results hold up, now we do. Not only that, we know that inflation was stronger than we anticipated. The strength of the gravitational waves is measured in a value known as r, where larger is stronger. It was found that r = 0.2, which is much higher than anticipated. Based upon earlier results from the Planck telescope, it was expected that r < 0.11. So there seems to be a bit of tension with earlier findings. There are ways in which this tension can be resolved, but just how is yet to be determined.

So this work still needs to be peer reviewed, and it needs to be confirmed by other experiments, and then the tension between this result and earlier results needs to be resolved. There is still much to do before we really understand inflation. But overall this is really big news, possibly even Nobel prize worthy. The results are so strong that it seems pretty clear we have direct evidence of cosmic inflation, which is a huge step forward. Before today we only had physical evidence back to when the universe was about a second old, at a time when nucleosynthesis occurred. With this new result we are now able to probe the Universe when it was less than 10 trillion trillion trillionths of a second old.

Which is pretty amazing when you think about it.