Tag Archives: big bang

Scientists Detect Direct Evidence of Big Bang’s Gravitational Waves

In the most anticipated announcement in physics since the discovery of the Higgs Boson, the first detection of a gravitational wave has been reported. If verified, the find will dispel any lingering doubts about Relativity theory, transform our understanding of the universe’s beginning and provide astrophysicists with a new tool to probe the universe. The importance of the detection is hard to overstate.

As part of his General Theory of Relativity, Einstein predicted that acceleration of large masses would cause waves to ripple through space in a manner analogous to ripples on the surface of a pond. Indirect evidence abounds for gravitational waves, but almost a century after Einstein predicted it direct evidence remained elusive – until today’s announcement by the Harvard-Smithsonian Center for Astrophysics. The paper is now available on arXiv.

The Cosmic Microwave Background (CMB) is the left over radiation from a four hundred thousand years after the  Big Bang stretched by the expansion of the universe to peak in the microwave part of the spectrum. In the mid 1990s astrophysicists proposed that the polarization of the CMB could provide evidence for gravitational waves from the birth of the universe. 

Photons can oscillate in different directions as they travel; up or down, side to side or even in a circular manner clockwise or anticlockwise. Hot sources produce photons with random orientations, but certain forces can create a bias where there is a preponderance of photons oscillating in a particular direction as they travel, making the radiation as a whole polarized.

The CMB was found to have a very slight polarization in 2002 as a result of density perturbations in the universe. Gravitational waves however, would be expected to induce a slightly different form of polarization. However, this pattern is so slight, and so vulnerable to false positives caused by other things, that there has been considerable skepticism that we would be able to detect the gravitational wave-induced polarization, at least with existing instruments.

The Plank space observatory has been studying the CMB since 2009, and some astronomers hoped it would be able to provide the evidence, but in the end the results came from an even more remote location, the Background Imaging of Cosmic Extragalactic Polarization (BICEP) detector located at the South Pole, where the cold dry air makes microwave astronomy possible.

“Detecting this signal is one of the most important goals in cosmology today. A lot of work by a lot of people has led up to this point,” said Prof John Kovac of the Harvard-Smithsonian Center for Astrophysics and a leader of the BICEP2 collaboration. 
 
Rumors of the discovery leaked well before the announcement leading to considerable debate online. While some astrophysicists were sceptical as to whether such a subtle signal could be detected with confidence, others not involved in the research were given prior access to the data. “I’ve seen the research; the arguments are persuasive, and the scientists involved are among the most careful and conservative people I know,” Professor Marc Kamionkowski of Johns Hopkins University told BBC News. 

Technical papers are available and are being poured over by researchers from teams worldwide.

The discovery of the CMB polarization by gravitational wave, should it stand the test of time, settles one question on its own, the debate over whether the early universe was inflationary. According to the most popular, but not universally accepted, theory of the early universe, 10-34 seconds after it began the universe experienced a period of rapid growth – expanding 100 trillion trillion times to something the size of a marble. 

An inflationary period would produce larger gravitational waves than would have been generated without. Nevertheless, even most inflationary models do not predict a gravitational wave large and polarizing enough to be detected by BICEP. 

The signal BICEP has found is so strong it makes many of the inflationary models of the early universe untenable, and leaves non-inflationary versions completely on the outer, suggesting the energy in the universe at that moment was well very much at the upper end of what was previously thought possible.

One of the reasons gravitational waves are so keenly sought is the hope that they will provide information about the crucial first moments of the universe in ways other instruments cannot. “People talk about the Square Kilometre Array as enabling us to detect the radiation from the Big Bang, but that is not strictly correct, Professor Jesper Munch of Adelaide University told Australasian ScienceFor the first 300 million years the universe was opaque to all electromagnetic radiation. However, gravitational waves could propagate through this early universe, and we can thus in principle detect signatures from the time of the Big Bang. It is probably the only way we can get signals from the origin of the universe.

Merely detecting a way is exciting, but we want more information than that it exists. The strength of the wave is expected to vary at different wavelengths. Finding out where it is strongest and weakest will tell us a lot about how the inflation occurred. The most important information of all is how energy dense the universe was during this era, and this could potentially be found by comparing wavelengths.

Gravitational wave perturbations from those first moments are directly dependent on the inflation, unlike density perturbations which are modulated by an unknown potential energy function. Consequently they would give us direct evidence of the details of energy of inflation in those first moments. 

Read more: http://www.iflscience.com/physics/scientists-detect-direct-evidence-big-bang%E2%80%99s-gravitational-waves

Simulation Gives New Look Into Early Universe

Despite advances in observational astronomy and experimental physics, the latest theories always seem to be slightly out of reach. Scientists use computer simulations to test these theories, looking for potential consequencesthat can be observed. Simulations are constantly being improved, and one of the latest might open a window into the first few minutes of the universe.

The new computer code,BURST,simulates different scenarios for what might have occurred immediately after the Big Bang by playing with the role and abundances of neutrinos and other fundamental particles. The predictions that the code delivers are as yet untestable, but the next generation of extremely large telescopes currently being built should be able to pick which is the correct scenario.

The BURST computer code allows physicists to exploit the early universe as a laboratory to study the effect of fundamental particles present in the early universe, said Mark Paris, co-author of theresearch, in a statement.

Our new work in neutrino cosmology allows the study of the microscopic, quantum nature of fundamental particles the basic, subatomic building blocks of nature by simulating the universe at its largest, cosmological scale.

The paper in which the code is showcased, published in Physical Review D, focuses on how neutrinos interact with themselves and other particles, the nuclear reaction happening and how the primordial plasma evolved. Theresearchers show, for example, that tweaks to the simulation lead to different abundances of deuterium, a hydrogen atom with a proton and a neutron. New telescopes could help established how much deuterium was produced and thus selectcertain models over others.

The frontiers of fundamental physics have traditionally been studied with particle colliders, such as the Large Hadron Collider at CERN, by smashing together subatomic particles at great energies, said University of California San Diegophysicist George Fuller, who collaborated with Paris and other staff scientists at Los Alamos to develop the novel theoretical model.

He went on to explain: Our self-consistent approach, achieved for the first time by simultaneously describing all the particles involved, increases the precision of our calculations. This allows us to investigate exotic fundamental particles that are currently the subject of intense theoretical speculation.

The BURST code allows for a new tool in answering the most fascinating puzzles in cosmology. Even without observations, it could take us closer to understanding dark energy, dark matter, and where the universe camefrom.

Read more: http://www.iflscience.com/space/numerical-simulation-gives-new-look-early-universe

Blue Galaxy Could Hold Clues To The Origin Of The Universe

Looking for clues about the early universe is often like the proverbialneedle-in-a-haystack, but once in a while astronomers are able to spot objects thatcan open new doors into the distant past.

This is the case of AGC 198691, a small blue galaxy located 30 million light-years away in the constellation of Leo Minor. The object has the smallest fraction of heavy elementsreferred to as metals in astronomyever seen in a galaxy, indicating that its material hasnt changed much since the Big Bang. A paper describing the discovery was published in the Astrophysical Journal.

“Finding the most metal-poor galaxy ever is exciting since it could help contribute to a quantitative test of the Big Bang,” Professor John J. Salzer, of Indiana University andsenior author of the paper, said in a statement.”There are relatively few ways to explore conditions at the birth of the universe, but low-metal galaxies are among the most promising.”

The metals like carbon, oxygen, and so onare produced by stars and spread throughout interstellar space by supernovae. AGC 198691 has just1.3 percent the metallicityof the Sun, a sign that very little star formation has happened since its formation.

Without much “contamination,”the composition of the galaxy, which has been nicknamed Leoncino (Italian for “little lion”), can be used to compare whether the predicted abundance of primordial hydrogen and helium matches with the observations.

Leoncinos uniqueness doesnt stop at its low metallicity. The galaxy is a “dwarf,” about 1,000 light-years across and made of a few million stars. An average system like the Milky Way is about 100 times wider and containsbetween 200 and 400 billion stars. Although Leoncino has some recently formed stars, responsible for its blue color, the galaxy has the lowest luminosity ever observed for this kind of object.

“We’re eager to continue to explore this mysterious galaxy,” added Salzer. “Low-metal-abundance galaxies are extremely rare, so we want to learn everything we can.”

The team is pursuing follow-up observations with several instruments, including the Hubble Space Telescope. A better understating of these galaxies will lay the groundwork for the potential detection of even more metal-poorobjects by the next generation of observatories.

Read more: http://www.iflscience.com/space/blue-galaxy-gives-clues-about-early-universe

10 Greatest Unsolved Mysteries In Physics

It can seem like an uphill challenge to try to understand the universe around us. We have found many answers to the mysteries in our world: how planets orbit the Sun, why an apple falls from a branch to the ground, and why the sky appearsblue. The quest to uncover all ofthe secrets of the universe is guaranteed to be filled with difficult challenges, unimaginable problems and a mountain of ingenuity neededto overcome them.

Many physicists have already wrestled with the riddles of existence, but there are many more conundrums to solve. Get ready for the ten greatest unsolved mysteries of physics… the enigmas that have evaded the most eminent mindsthe world has ever known.

Dark energy

We can’t see it andwe can’t feel it, but we can test for it, and nobody knows what it is. In spite of this, scientists think that dark energy makes up around 70% of the universe. It was imagined to explain why galaxies don’t just drift apart but instead accelerate away from each other. You can think of it as a repulsive gravity that pushes matter apart. How it works, however, is still a mystery.

Dark matter

The other “dark” substance in our universe. Dark matter, like dark energy, cannot be seen or felt. This elusive substance has some differences to dark energy though; the only way that we have observed it is indirectly. We know that there must be more matter in the universe than we can see becausewe can measure its gravitational effects, but no one knows exactly what makes up this mysterious stuff.

It’s a wave… it’s a particle!

Rays of light have a split personality. They create interference patterns that are typical of waves. They reflect offsurfaces, suggesting that they could be a wave or a particle, or both at the same time. They can also be used to liberate electrons from their shells: something that indicates that they are particles. But how does light determine whether it acts as a particle or a wave?

Time, the onwardmarch

We only get older, not younger. Trees only get taller; they don’t return to acorns. Our Sun only ever uses up its fuel, never returning to a coolball of hydrogen gas. Time only goes in one direction…but why is it impossible for us to reverse the clocks?

We are living in a hologram

This one boggles the mind. The universe, everything we see and feel and experience, may actually have two spatial dimensions. Think of a 2D hologram, like the one on the back of a credit card: it can have all of the information of a 3D image but in only two dimensions. Some scientists have postulated that our universe is like the hologram on your credit cards: space seems like it has three dimensions, but it may turn out that all we are seeing is a projection from a 2D universe outside of our perception.

Matter and antimatter

There is a definite discrepancy between the ratios of these two substances. There was supposed to be an equal amount of ordinary matter and antimatter particles with the same mass but opposite chargein the early universe, but now the universe is overwhelmed with regular matter. Many theories have been thrown around, for examplethat particle genesis favored one way of creating matter, but nothing conclusive has popped up. The mystery of how matter “won” over antimatter may be revealed in the newly-upgradedLarge Hadron Colliderat CERN.

The lifetime of the universe

This mystery,the endof the universe,might not keep you up at night, but it will certainly be of concern to beings alive far into the future.This epiceventispredicted to occur inabout 10 billion years. Two opposing theories are the Big Crunch and the Big Rip. Neither of these outcomes sound terribly fun. The big crunch is the opposite of the Big Bang all of the pieces of matter in the universe will stop accelerating away from each other and start accelerating towardeach other. A boiling collision of all ofthe matter in the universe ensues (and mankind is unlikely to survive that). The Big Rip is where all of the pieces of matter in the universe continue to accelerate away from each other, faster and faster until eventually space-time moves so fast that it rips atoms apart(mankind is also unlikely to survive that one).

These two possibilities aren’t the only possible outcomes for the universe sadly it seems unlikely that our generation will ever know its fate.

Why can’t we imagine four dimensions?

We little humans struggle to envision a world with four spatial dimensions. Some theories (such as string theory) need as many as eleven dimensions to be hypothetically possible. If string theory turned out to be correct, we’d have to figure out how there are sixmissing dimensions tangled up in our reality. I can feel a headache coming on…

Why does light have a universal speed limit?

c, the speed of light constant, is valued at 3×108meters persecond. But whythis figureand not, for example,4×1020m/s?Is it a random digit pulled out of a bag of numbers when a new universe explodes into existance? It’s currently impossible to know why the speed of light is the speed that it is… all we know is that our universe couldn’t exist without this limit.

Unifying the big and the small

Everything big, like stars and black holes, is made up of small things: particles. Einstein’s laws of relativity govern the very big, while quantum mechanics is king in the realm of the very small. But physicists can’t seem to jam the two theories together. The trouble is that gravity just doesn’t appear to work on the nanoscopic scale. And bizarrequantum effects, like quantum tunneling (whereby an atom can “tunnel” through an otherwise impenetrable boundary), can’t be applied to planets or stars. Your eyes would likely pop if the Moon suddenly “tunneled” through the Earth. It seems barmy that there would be one theory for everything big and another for everything small. Some scientists are trying to tackle this problem, and even making headway, but the missing link is still incredibly elusive.

Read more: http://www.iflscience.com/physics/greatest-mysteries-physics

Planck Reveals Most Detailed Map Yet Of The Milky Way’s Magnetic Field

In a collaborative effort, astrophysicists have used data collected from the Planck Space Telescope to generate the most detailed map of our galaxy’s magnetic field yet, which could further our knowledge of the very early universe. The team that produced the map includes scientists from the University of British Columbia and the Canadian Institute for Astrophysics (CITA) at the University of Toronto. The results are described in four forthcoming papers within the journal Astronomy and Astrophysics.

Since its discovery in 1964, scientists have been measuring the Cosmic Microwave Background (CMB) in order to find out more about the birth and evolution of the universe. The CMB is the afterglow of the Big Bang and dates from around 380,000 years after this event. The European Space Agency’s Planck Space Telescope, which was launched in 2009, has given us the most comprehensive picture of the CMB yet, but that’s not all it can be used for.

Planck is able to pick up light from tiny dust particles within our galaxy and can determine the directionality of the vibrations of these light waves, which is called polarization. This information can then be used to deduce the orientation of the magnetic field lines.

According to Douglas Scott, an astrophysicist at the University of British Columbia, the magnetic field of the Milky Way is important for investigating the many phenomena within it. “Planck has given us the most detailed picture of it yet,” he says.

“Dust is often overlooked but it contains the stuff from which terrestrial planets and life form,” said Professor Peter Martin, CITA, who studies dust in the Milky Way. “So by probing the dust, Planck helps us understand the complex history of the galaxy as well as the life within it.”

Planck data to be released later this year will help scientists confidently distinguish signal from the Milky Way from the polarized CMB signal, which will be very handy for those investigating the birth and evolution of the universe. It should also further our knowledge of the universe from as early as one second after the Big Bang to the time when the first stars were being born.

“These results help us lift the veil of emissions from these tiny but pervasive Galactic dust grains which obscure a Planck goal of peering into the earliest moments of the Big Bang to find evidence for gravitational waves created in that epoch,” says CITA Professor J. Richard Bond

Read more: http://www.iflscience.com/space/planck-reveals-most-detailed-map-yet-milky-ways-magnetic-field

Gravity Saved the Universe After the Big Bang

During the accelerated expansion of the early universe, the production of the Higgs boson—the elementary particle responsible for giving mass to all particles—should have led to instability, followed by collapse. At least that’s what some recent studies suggest. 

But the universe didn’t collapse immediately after the Big Bang, and now researchers think they know why. The answer isn’t some new physics that we have yet to understand: It’s quite simply, gravity. The spacetime curvature (gravity, in effect) provided the stability needed for the universe to survive early expansion, according to a new study published in Physical Review Letters this week.

An international team led by Matti Henrikki Herranen from the University of Copenhagen studied the interaction between the Higgs particle and gravity, and how it varies with energy. Even a small interaction, they found, would be enough to stabilize the universe against decay. 

“The Standard Model of particle physics, which scientists use to explain elementary particles and their interactions, has so far not provided an answer to why the universe did not collapse following the Big Bang,” study co-author Arttu Rajantie of Imperial College London says in a news release. “Our research investigates the last unknown parameter in the Standard Model—the interaction between the Higgs particle and gravity.”

He adds: “This parameter cannot be measured in particle accelerator experiments, but it has a big effect on the Higgs instability during inflation. Even a relatively small value is enough to explain the survival of the universe without any new physics!” Here’s a timeline of the universe: 

Next, the team wants to look at this interaction in more detail using cosmological observations from current and future European Space Agency measurements of cosmic microwave background radiation (above) and gravitational waves. The cosmic microwave background is a snapshot of the oldest light in the universe, back when it was just 380,000 years old. The observations could help explain the effect that their interaction would have had on the development of the early universe. “If we are able to do that,” Rajantie says, “we will have supplied the last unknown number in the Standard Model of particle physics.” 

Images: D. Ducros, ESA and the Planck Collaboration (top), NASA/WMAP Science Team via Phys.org (middle)

Photo Gallery

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