Presenting Deus: A Full Blown Simulation of the Entire Universe

Scientists have been able to recreate the entire Universe inside a computer for the first time ever. A simulation running on a supercomputer, tracking a mind boggling 550 billion particles as they evolve, has been able to recreate the structure of the Universe right from the Big Bang to the present day.

Simulating the Standard Model of Cosmology

This is the first in the series of three simulations to be carried out on GENCI’s new supercomputer, CURIE at CEA’s TGCC (Tres Grand Centre de Calcul) performed by researchers from Laboratoire Univers et Theorie (LUTH). This takes into account the standard model of cosmology with the cosmological constant built in. Successive runs will improve upon this result with more data, especially about the distribution of dark matter and dark energy. The project, called Deus: full Universe run, will seek answers to the cosmological questions in a way similar to what the LHC follows in order to get answers.

Comparing Deus' size to previous simulations! Bottomline: Deus is HUGE!

Why simulation?

The physics at the LHC is massively complicated by the presence of so many particles and so many end states of a certain collision. It is impossible to analytically solve for the end state, so scientists use models before they begin an experiment. These simulations reveal what the most likely result of a certain collision is given certain parameters and bounds on certain numbers. The actual run either confirms the simulation, or discards it. This is a far more efficient process than reconstructing the interaction by looking at the end states, which is the other alternative.

The Deus simulation does something like that. They let the 550 billion points evolve and see what the end state is. This has enabled them to count the number of galaxy clusters which are more massive than a hundred thousand billion solar masses (that’s VERY heavy, by the way) and the number comes out to be 144 million. The first galaxy cluster formed 2 billion years after the Big Bang, according to the simulation. It also shows the most massive galaxy cluster – with a mass of 15 quadrillion (or 15 thousand trillion) solar masses!

 

Relics of the Early Universe

The simulation also revealed fingerprints of the inflationary era in the form of fluctuations in the Cosmic Microwave Background Radiation. If the Big Bang and inflation is true, then there must be radiation left over, which is constantly weakening. This permeates all of the space in the Universe, thus the name Cosmic Microwave Background (CMB). It is believed that some quantum fluctuation, growing under the effect of gravity, gave rise to the galaxy and clusters we see today. The CMB was studied thoroughly by the WMAP studies. They also showed up in the simulation.

Where are we? That dot - that single dot - is the entire Milky Way!

The simulation also confirmed the presence of dark matter and gave a hint of how it might be distributed throughout the Universe. Present in this primordial virtual cosmic soup is the Baryon Acoustic Oscillations or BAO. This might be the answer to the long standing problem of baryon asymmetry – why matter outnumbers anti-matter in the Universe, whereas they should have been produced in equal numbers in the Early Universe.

Computing power – the sky is the limit

CURIE is one of the largest supercomputer facilities in the world. The whole simulation has taken a few years to put together. The whole project is expected to use more than 30 million hours (or 3500 years) of computing time on all CPU’s of CURIE. The amount of data processed comes out to be 150 PB (peta bytes). This amounts to all the data on 30 million DVD’s. State-of-the-art compression technology has allowed researchers to reduce this entire jungle to 1 PB.

Future

Two more simulations are to follow! They will test out rival cosmological models. The simulation is also expected to reveal structures we have not been familiar with before. This will provide scientists a search parameter for current projects like PLANCK and future ones like EUCLID.

More info at this CNRS press conference: http://www2.cnrs.fr/en/2013.htm

Gravitational Lensed “Cosmic Mirage” Is Definitive Proof of Accelerated Expansion of Universe

The Universe is accelerating, says a team of researchers led by Masamune Oguri, Kavli IPMU and Naohisa Inada at Nara National College of Technology, courtesy the data acquired by observing distant quasars. This is supplementary to the studies of distant supernovae, which also showed that the Universe’s expansion is accelerating, and for which the 2011 Nobel Prize in Physics was given. This study with quasars again shows that dark energy is definitely present, but we still don’t know what it might be.

Larger Data and more inferences

The data is derived from the Sloan Digital Sky Survey (SDSS), the huge collaborative experiment responsible for tracking about 100,000 quasars for nearly 10 years, with nearly 50 new quasars discovered in the last few years. Quasars are bright objects, believed to be formed, or at least fuelled, by the accretion of gas and dust by a supermassive black hole. The infalling material glows due to the enormous heat produced and can thus be detected from very far away. This makes them ideal for mapping the gravitational lensing occurring in the Universe.

Prof. Oguri, heading the study, says:

In 2011, the Nobel Prize in Physics was awarded to the discovery of the accelerated expansion of the universe using observations of distant supernovae. A caution is that this method using supernovae is built on several assumptions… Our new result using gravitational lensing not only provides additional strong evidence for the accelerated cosmic expansion, but also is useful for accurate measurements of the expansion speed, which is essential for investigating the nature of dark energy.

The Science of Gravitational Lensing

Gravitational lensing refers to the bending of light due to the presence of matter in the path of light, as explained by Einstein’s General Theory of Relativity. This process creates (at least) two identical images of one object, separated by a gap, thus the name ‘Cosmic Mirage’, referring to the similar process by which mirages on Earth are created.

The formation of a Cosmic Mirage. The figure explains why the accelerated expansion increases the chances of gravitational lensing and why the images separate out further. (Courtesy: SDSS)

The farther away the quasar, the greater its chances to be gravitationally lensed. Accelerated expansion of the Universe increases the distance of the quasar from us and thus the images also seem to separate (refer to figure above). This can be used to deduce how fast the quasars are receding from us. By plotting the velocity graph (velocity versus distance curve), we can see the deviation from the straight line expected from Hubble’s law, if the Universe was expanding at a constant rate. Sure enough, there is deviation and all the deviations fall on a curve, showing that it’s not just a mere statistical fluctuation or measurement error. The Universe is indeed accelerating! And this suggests that the estimates for dark energy are also not very off.

Note the two distinct images formed by gravitational lensing in the zoomed in inset. This was captured by the Hubble Space Telescope and the quasar - SDSSJ1226-0006 - has been tracked by the SDSS. (Courtesy: SDSS and Hubble Space Telescope)

Dark Energy in Einstein’s Theory

Einstein’s theory of General Relativity allows for an expanding Universe without any extraneous assumptions. However, this expansion should have been at uniform speed. But it seems that the expansion rate is increasing. To get this prediction from Einstein’s equations, scientists tweak it a bit, adding a ‘cosmological constant’ term. This adds a bit of energy per unit volume of the Universe, contributing a lot to the entire energy of the Universe. By adjusting the sign of this extra term, the universe can be made to be accelerating.

In fact, it can be shown that we are exiting a phase dominated by matter, where the major contribution to energy comes from matter, and entering a phase dominated by the cosmological constant. This inevitably leads to accelerated expansion. We might not be able to see any galaxies in another 5-10 billion years, if the accelerated expansion of the Universe continues unabated.

The SDSS data also shows that treating dark energy as the cosmological constant is not such a wrong thing to do.

The future of the SDSS project is Planck and the SuMIRe projects. Both aim to study the distribution of cosmic dark energy and all this in the not-too-distant exciting future!

Source and more info at the IPMU original site: http://www.ipmu.jp/node/1281

Do Laws Of Physics Vary Across The Universe?

The warm smugness that a physicist often feels when he/she says that a phenomenon or a law is universal’ may be an illusion. If a team of researchers from Swinburne University of Technology is to be believed, then their data shows that the laws of physics might actually vary throughout the Universe. They have measured the value of the fine-structure constant, a fundamental dimensionless parameter occurring frequently in Quantum Electrodynamics, and have found that this varies throughout the Universe.

What is the Fine-Structure Constant?

The fine-structure constant, commonly called alpha’, is exactly 1/137 in its value. The constant manifests itself in the expansion parameter as one tries to expand in the theory of Quantum Electrodynamics, the physics explaining electrons, light and their interaction. The constancy of the value of alpha is crucial in establishing the universal strength of the electromagnetic force. It would mean that the strength of coupling (or interactions) between the photons (particles of light) and electrons varies throughout the Universe.

The circles represent Keck points, Triangles are both Keck and VLT. The size represents the confidence in the data points. Notice that most of the points to the middle - local to us - are black, indicating no deviation from the 1/137 value. The points farther off are not so. (Courtesy: Swinburne University of Techology, John Webb et al.)

The Research Team

A team of researchers comprising Professor John Webb, Professor Victor Flambaum and colleagues, all from University of South Wales (UNSW), Swinburne University of Technology and the University of Cambridge, had already got a hint of the supposed deviation from the accepted value of alpha as early as a decade ago. While they had used the Keck telescope in Hawaii to obtain all their data then, they’ve used the Very Large Telescope (VLT) in Chile this time. They’ve more than double their number of data points and it seems to support what they had initially thought. The confidence level has grown to a respectable 3 sigma. Professor Webb shares his excitement:

In one direction – from our location in the Universe – alpha gets gradually weaker, yet in the opposite direction it gets gradually stronger.

What Are The Consequences?

It is always the habit of scientists to back up initial observations with enough observations to fully confirm the fact. It is, thus, too early to comment what implication this will have on our understanding of the cosmos, As far as we know, the Universe is spatially homogenous (same from all points in space) and isotropic (looks the same in all directions there is no preferred direction) on a large scale (bigger than the length scale of galaxies). This is one of the basic principles of Einstein’s General Theory of Relativity  Cosmology (i.e. application of Einstein’s General Relativity – the modern theory of gravity- on the scale of the Universe). If alpha varies from point to point, then the homogeneity of space is destroyed. We can still have a weaker’ version of the homogeneity condition and General Relativity will still be true, but, having worked so well, we would like the homogeneity principle to be rigidly true. Only further observations, backed up by theory, can tell us more.

A pre-print of the arXiv paper by Webb et al is available here:  http://arxiv.org/abs/1008.3907v1
Astrophysicist Sean Carroll says that the value of alpha is probably constant. Here’s an article from him written a year ago:  http://blogs.discovermagazine.com/cosmicvariance/2010/10/18/the-fine-structure-constant-is-probably-constant/

 

Neil deGrasse Tyson To Host Sequel To Carl Sagan’s Masterpiece ‘Cosmos’ Series

Some are regarding this as a momentous rebirth and others as horrible blasphemy. Neil deGrasse Tyson, famous for his animated and vociferous explanations of science, especially the various aspects of cosmology, to the general public will be hosting a sequel to the famous ‘Cosmos: A Personal Voyage’ series by Carl Sagan.

The great Sagan (left) and Neil deGrasse Tyson (right)

The path-breaking, awe-inspiring 13-part series by the late Carl Sagan, an American astronomer and science populariser, is a benchmark for documentaries made for popularizing science. This represents the pinnacle of Sagan’s tireless effort in teaching science to the public in a palatable form, trying to get the beauty and awe of the subject across rather than the complexity and mathematics of it. And he was damn good at it.

Evergreen Sagan : Remembering the Unforgettable

No matter how good Sagan’s original series was, it is still three decades old. This means that the special effects used in it are infantile compared to today’s effects and, since science has grown as usual, many facts also need to be revised. In fact it is a testament to Sagan’s foresight and understanding of science that, even today, the series will not seem old. Many predictions that Sagan made in the series are active research areas of today.

Among the many unforgettable parts of the series, was the spine-tingling Pale Blue Dot. In 1991, Voyager had turned its camera around and focussed on the inner planets, and, lo and behold, there was Earth, a pale blue pixel of light, suspended in a sunbeam. Carl Sagan’s lyrical presentation of the emotional content of that one pixel of light is immortal.

Then, there was the famous phrase: Billions and Billions, with extra stress on the B’s, a signature of Sagan. This phrase famously never occurs even once in the series and has been taken up by the media due to its sonorous qualities.

Immortal lines include In order to make an apple pie from scratch, you must first invent the Universe’, Somewhere, something incredible is waiting to be known’, The beauty of a living thing is  not  the atoms that go into it.  But  the way those atoms are  put together‘ and The Universe seems neither benign nor hostile, merely indifferent’.

The New Show: Big Shoes to Fill

The 13-part sequel series will be made by Seth MacFarlane (yes, that Family Guy writer) in collaboration with Ann Druyan (also Sagan’s widow) and Steven Soter. It will be aired in 2013.

Carl Sagan, in his element, is irreplaceable. Neil deGrasse Tyson will have his work cut out for him, as inevitable comparisons will be drawn between him and Sagan. Replacing Sagan might be impossible, but if there is anyone who can come close to sharing that infectious enthusiasm, while delivering passion-laced explanations of science that sound poetic, it has to be Neil deGrasse Tyson. He has proved his mettle as the host of NOVA ScienceNOW on PBS for the last five years. Watch him in a short video here:

Here’s the bad news: it won’t be aired on Discovery or PBS, but rather on Fox. Fox has a rather poor track record with science shows and shows with dropping ratings, unlike Discovery. Let’s leave you with a musical presentation from the Symphony of Science series, having both Sagan and Tyson (and Feynman!):

For evermore shall those stressed b’s in billions’, a trademark of Sagan, ring in our ears…

CERN’s New Einstein Observatory To Detect Gravitational Waves

CERN’s at it again, but it’s not particle physics. Einstein’s also at it again, but this time, it isn’t the famed grizzly haired scientist. A group of European scientists working with CERN will soon propose a design for a telescope the Einstein Observatory  – which will be much better than any other known telescope of its kind. The catch: This one will detect gravitational waves rather than optical radiation or radio waves.

What is the Einstein Observatory

The Einstein Observatory (EO) is a ‘third-generation’ gravitational wave detector and it is designed to be at least a 100 times more sensitive that its existing predecessors. The principle of detection is simple and classic. The arms of the Observatory, each several kilometers long and each being a laser beam will shrink or expand ever so slightly if a gravitational wave passes. This will cause a change in the interference pattern in a central photo-detector. Let’s look at this in more detail.

Einstein’s theory of General Relativity predicts that gravitational energy, stored in gravitational fields, should be released as waves, just like energy in electromagnetic fields is released by electromagnetic waves (which we call light). The problem is that, unlike light, the energy of a gravitational wave is so small that if a typical one passes by earth right now, the earth will shrink and then expand by the breadth of a proton which is much much smaller than even an atom. Detecting such small perturbations is a huge challenge that has so far been unconquered. Relativity predicts that gravitational waves of comparatively large magnitude are emitted by violent cosmic events, like merging of black holes, or fusing of neutron stars, or even supernova explosions. These will be the typical gravitational waves scientists hope to detect with EO. The success of Einstein’s theory has been such that no one doubts the existence of gravitational waves, even though one hasn’t been detected inspite of dedicated search.

Gravity waves are generated by violent cosmic event, like neutron stars merging (An artist's impression)

What EO intends to do is this: there is a particular way two beams of light interfere with each other.

Apparatus for the MM experiment

They form a well-known pattern called an interference pattern (you might see these patterns when water waves interfere). A slight shift in the path a beam of light travels will disturb these patterns. The process is extremely sensitive – and if the beams travel a long distance before interfering, the sensitivity increases. (For science buffs: This is the same principle first used by Michelson in his famous experiment for measuring the speed of light and later, the most famous ‘failed’ experiment in history. This failed experiment, known simply as Michelson-Morley experiment, aimed to detect a change in the speed of light in different directions so as to confirm the aether hypothesis. None was detected. Einstein would later build his Special Theory of Relativity around this result.)

More on the EO

The EO will be housed 100 to 200 meters below ground, in order to minimize the seismic activity of the ground and its effect on the telescope. The EO will be extremely sensitive in the range 1 Hz to 10 kHz, which is the frequency band for the gravitational waves. The Einstein Observatory will lead a scientific revolution, is what Michele Punturo, scientific coordinator of the design, says. The data from the EO will be corroborated and complemented by data from various gamma-ray and X-ray telescopes.

The proposed design of the Einstein Observatory

The EO is actually two interferometers one to detect gravitational wave signals from 2-40 Hz and the other to detect till 10 kHz. This is required, since detecting at low frequencies is a very difficult job and needs dedicated instruments tuned for doing only that.

EO will hope to improve upon existing gravitational wave telescopes like LIGO, Virgo and TAMA (all first generation), and even Advanced LIGO and Advanced Virgo (second generation). The design will be presented at European Gravitational Observatory site in Pisa, Italy.

It is of utmost importance to the progress of cosmology that the telescope, like the illustrious scientist it is named after, becomes as successful as his theories.

Einstein Confirmed Again: Dark Energy Present In The Universe

The grand old man of Physics is proved right once again. Albert Einstein was vindicated yet again by a survey, which confirmed the presence of Dark Energy in the Universe. The ‘WiggleZ Dark Energy Survey’ was conducted by 26 astronomers from 14 countries using the latest in spectrograph technologies to map out more than 200,000 galaxies, many halfway across the Universe to confirm this startling fact.

What is Dark Energy?

Dark Energy is the name given to the unknown entity believed to be behind the acceleration of the expansion of the Universe. It was Edwin Hubble, who in 1932, first noticed that the Universe was actually expanding. This gave a huge boost to the Big Bang theory, which says that the Universe came out of an ultra-dense singularity 14-15 billion years ago. Scientists have been expecting the expansion to slow down as time wears on, as then gravity will eventually dominate. What scientists found, instead, was that the Universe was expanding at an ever-increasing rate. It is believed that some mysterious source of energy was aiding the expansion process, thus named Dark Energy.

No one has come up with a proper explanation of Dark Energy, despite there being a number of hypotheses and models. Dark Energy supposedly makes up 73% of the Universe, Dark Matter 23 % (which is NOT the same as Dark Energy; Dark Matter slows down the expansion) and the rest 4% – is ordinary matter – stars, galaxies, nebulae and super-clusters.

Where Einstein fits in…

Einstein had almost predicted the expansion of the Universe in his Theory of General Relativity, but in an uncharacteristic situation in which his nerves weakened, he introduced a factor in his equations which predicted a static Universe. This amounted to including in his equations, a cosmological constant a ‘fudge factor’ which gives vacuum a repelling force, effectively enabling the Universe to counter its own gravity and preventing self-collapse. Later, Einstein would rue this as his ‘greatest blunder’. Now, it seems that the great man was not wrong!

Inflationary theories of modern cosmology use this idea of a cosmological constant to explain the supposed period of rapid expansion right after the Big Bang called inflation. Now, with the increasing rate of expansion, it seems that the cosmological constant was the genius’ masterstroke rather than a botch-up.

The WiggleZ survey

The WiggleZ survey, conducted by an Australian-based group led by Dr. Michael Drinkwater, used the latest in spectrography, thanks to latest Australian technology to survey galaxies more than 200000 of them some 7 billion light years away. Light takes a finite time to travel from one place to another, because of its finite speed. Thus the light from 7 billion light years away took 7 billion years to reach here. This means that we are seeing galaxies in the form they were 7 billion years ago, essentially looking back in time! (Thus, the easiest way to glance into the past is to just see. The farther away the object you see, the farther away in time it is!). The WiggleZ survey can map 392 galaxies in an hour!

Do Structures such as these give clues to Dark Matter and Energy?

Though, this doesn’t tell us the constituents of Dark Energy (or Dark Matter, which is also a mystery), it gives definitive confirmation of its existence. It gives scientists confidence that Einstein’s theory is not failing, and that Dark Energy can indeed be reconciled with General Relativity. The survey is exhaustive measuring both the pattern of distribution of galaxies in the Universe and the rate of formation of the galaxy clusters, essentially giving scientists a two-way confirmatory proof of Dark Energy.

So, there it is again! Einstein is proved right again, and in spectacular fashion. 96% of the stuff in the Universe is unknown, but at least we know that it’s there. Some consolation and a lot of work to be done!

Einstein Passes Strictest Test: NASA’s Gravity Probe-B Proves General Theory of Relativity Correct

It is the culmination of a five-decade old project. Gravity Probe-B (GP-B) has detected a minuscule, but theoretically expected, tilt in its magnetic needles, essentially proving Einstein correct, yet again.

einstein
"Told ya"

The Physics

Einstein’s general theory of relativity (GTR), the most accurate description of gravity known to science, predicts two critical phenomenon, which differentiates it from Newton’s theory of gravity: geodetic effect and frame dragging. The geodetic effect is just a technical term to describe the well known phenomenon of warping of space-time by massive objects. Light, which appears to follow a straight line path, will bend, following the curvature of space-time. Frame dragging refers to the phenomenon in which space-time seems to be ‘dragged’ along with any rotating gravitational body. It’s as if there is friction between the body and surrounding space-time.

Physicist Francis Everitt, of Stanford University, lead researcher in the GP-B experiment, explains it better:

Picture the Earth immersed in honey, and you can imagine the honey would be dragged around with it. That’s what happens to space-time. Earth actually drags space and time around with it.

francis everitt
Francis Everitt

If Einstein’s theory is really true, then these effects should lead to a tiny, but observable, in the orientation of a suspended gyroscopic magnet.

The Project

The project was proposed by theoretical physicist Leonard Schiff in 1959, when he was the head of the Stanford Physics Department. In 1962, Schiff and team recruited Everitt. In 1963, NASA got interested in the project, a full 7 years before the lunar launch.

The experimental confirmation of such tiny effects was a huge challenge. Einstein, himself was of the opinion that

their magnitude is so small that confirmation of them by lab experiments is not to be thought of.

Thankfully, Einstein was wrong. In 2004 (after 41 years), the Gravity Probe-B was launched by NASA.

The spacecraft had four ping-pong sized gyroscopes. These were made of fused quartz spheres (the most spherical spheres ever made) and uniformly covered by a layer of Niobium and cooled by Liquid Helium. At liquid Helium temperatures, Niobium becomes a superconductor, allowing electrical currents to flow without any resistance. Once an electrical current is setup, it doesn’t decay.

One of the four Gyroscopes on Gravity Probe B
gravity probe b
Gravity Probe B

Rotating currents setup a magnetic field pointing in a particular direction. The magnetic pointer was set to point at IM Pegasi, a single star. The prediction is that, if Einstein is right, minute changes in the direction of the magnetic pointer would occur.

The Result

The pointer shifted by 6000 milli arcseconds in one year that’s the breadth of a human hair seen from 10 km away. However, the extent was just as expected, confirming GTR yet again. The geodetic effect was confirmed to within 0.23% accuracy and the frame-dragging to about 20%.

Beyond just Einstein

Even though the primary objective of this project was to verify GTR in the most accurate way possible, GP-B has also, unwittingly, contributed a lot to the development of various technologies, most notably the technology to build better gyroscopes. It has made key contributions to various developments on the COsmic Background Explorer (or COBE), which was instrumental in demonstrating that the Universe is expanding just as the Big Bang Theory claims.

Consequences

The positive GP-B results will help scientists understand gravity better, especially in extreme cases, like black holes. Many people ask, why test Einstein further? Well, even though he has been thoroughly tested and has passed all tests with flying colors, that’s how science proceeds. The more stringent the test, the more credibility the theory gains when it passes it.