Parallel Universes

The Theory of Parallel Universes

The multiverse is a theory in which our universe is not the only one, but states that many universes exist parallel to each other. These distinct universes within the multiverse theory are called parallel universes. A variety of different theories lend themselves to a multiverse viewpoint.

Not all physicists really believe that these universes exist. Even fewer believe that it would ever be possible to contact these parallel universes.

Level 1: If you go far enough, you’ll get back home

The idea of Level 1 parallel universes basically says that space is so big that the rules of probability imply that surely, somewhere else out there, are other planets exactly like Earth. In fact, an infinite universe would have infinitely many planets, and on some of them, the events that play out would be virtually identical to those on our own Earth.

We don’t see these other universes because our cosmic vision is limited by the speed of light — the ultimate speed limit. Light started traveling at the moment of the big bang, about 14 billion years ago, and so we can’t see any further than about 14 billion light-years (a bit farther, since space is expanding). This volume of space is called the Hubble volume and represents our observable universe.

The existence of Level 1 parallel universes depends on two assumptions:

• The universe is infinite (or virtually so).

• Within an infinite universe, every single possible configuration of particles in a Hubble volume takes place multiple times.

If Level 1 parallel universes do exist, reaching one is virtually (but not entirely) impossible. For one thing, we wouldn’t know where to look for one because, by definition, a Level 1 parallel universe is so far away that no message can ever get from us to them, or them to us. (Remember, we can only get messages from within our own Hubble volume.)

Level 2: If you go far enough, you’ll fall into wonderland

In a Level 2 parallel universe, regions of space are continuing to undergo an inflation phase. Because of the continuing inflationary phase in these universes, space between us and the other universes is literally expanding faster than the speed of light — and they are, therefore, completely unreachable.

Two possible theories present reasons to believe that Level 2 parallel universes may exist: eternal inflation and ekpyrotic theory.

In eternal inflation, recall that the quantum fluctuations in the early universe’s vacuum energy caused bubble universes to be created all over the place, expanding through their inflation stages at different rates. The initial condition of these universes is assumed to be at a maximum energy level, although at least one variant, chaotic inflation, predicts that the initial condition can be chaotically chosen as any energy level, which may have no maximum, and the results will be the same.

The findings of eternal inflation mean that when inflation starts, it produces not just one universe, but an infinite number of universes.

Right now, the only noninflationary model that carries any kind of weight is the ekpyrotic model, which is so new that it’s still highly speculative.

In the ekpyrotic theory picture, if the universe is the region that results when two branes collide, then the branes could actually collide in multiple locations. Consider flapping a sheet up and down rapidly onto the surface of a bed. The sheet doesn’t touch the bed only in one location, but rather touches it in multiple locations. If the sheet were a brane, then each point of collision would create its own universe with its own initial conditions.

There’s no reason to expect that branes collide in only one place, so the ekpyrotic theory makes it very probable that there are other universes in other locations, expanding even as you consider this possibility.

Level 3: If you stay where you are, you’ll run into yourself

A Level 3 parallel universe is a consequence of the many worlds interpretation (MWI) from quantum physics in which every single quantum possibility inherent in the quantum wavefunction becomes a real possibility in some reality. When the average person (especially a science fiction fan) thinks of a “parallel universe,” he’s probably thinking of Level 3 parallel universes.

Level 3 parallel universes are different from the others posed because they take place in the same space and time as our own universe, but you still have no way to access them. You have never had and will never have contact with any Level 1 or Level 2 universe (we assume), but you’re continually in contact with Level 3 universes — every moment of your life, every decision you make, is causing a split of your “now” self into an infinite number of future selves, all of which are unaware of each other.

Though we talk of the universe “splitting,” this isn’t precisely true. From a mathematical standpoint, there’s only one wavefunction, and it evolves over time. The superpositions of different universes all coexist simultaneously in the same infinite-dimensional Hilbert space. These separate, coexisting universes interfere with each other, yielding the bizarre quantum behaviors.

Of the four types of universes, Level 3 parallel universes have the least to do with string theory directly.

Level 4: Somewhere over the rainbow, there’s a magical land

A Level 4 parallel universe is the strangest place (and most controversial prediction) of all, because it would follow fundamentally different mathematical laws of nature than our universe. In short, any universe that physicists can get to work out on paper would exist, based on the mathematical democracy principle: Any universe that is mathematically possible has equal possibility of actually existing.

The mystery of Einsteins Brain

Albert Einstein is widely regarded as a genius, but how did he get that way? Many researchers have assumed that it took a very special brain to come up with the theory of relativity and other stunning insights that form the foundation of modern physics. A study of 14 newly discovered photographs of Einstein's brain, which was preserved for study after his death, concludes that the brain was indeed highly unusual in many ways. But researchers still don't know exactly how the brain's extra folds and convolutions translated into Einstein's amazing abilities.

The story of Einstein's brain is a long saga that began in 1955 when the Nobel Prize-winning physicist died in Princeton, New Jersey, at age 76. His son Hans Albert and executor Otto Nathan gave the examining pathologist, Thomas Harvey, permission to preserve the brain for scientific study. Harvey photographed the brain and then cut it into 240 blocks, which were embedded in a resinlike substance. He cut the blocks into as many as 2000 thin sections for microscopic study, and in subsequent years distributed microscopic slides and photographs of the brain to at least 18 researchers around the world. With the exception of the slides that Harvey kept for himself, no one is sure where the specimens are now, and many of them have probably been lost as researchers retired or died.

Over the decades, only six peer-reviewed publications resulted from these widely scattered materials. Some of these studies did find interesting features in Einstein's brain, including a greater density of neurons in some parts of the brain and a higher than usual ratio of glia (cells that help neurons transmit nerve impulses) to neurons. Two studies of the brain's gross anatomy, including one published in 2009 by anthropologist Dean Falk of Florida State University in Tallahassee, found that Einstein's parietal lobes—possibly linked to his remarkable ability to conceptualize physics problems—had a very unusual pattern of grooves and ridges.

But the Falk study was based on only a handful of photographs that had been previously made available by Harvey, who died in 2007. In 2010, Harvey's heirs agreed to transfer all of his materials to the U.S. Army's National Museum of Health and Medicine (NMHM) in Silver Spring, Maryland. For the new study, published today in the journal Brain, Falk teamed up with neurologist Frederick Lepore of the Robert Wood Johnson Medical School, New Brunswick, in New Jersey, and Adrianne Noe, director of NMHM, to analyze 14 photographs of the whole brain from the Harvey collection that have never before been made public. The paper also includes a "roadmap" prepared by Harvey which links the photographs of the brain to the 240 blocks and the microscopic slides prepared from them, in hopes that other scientists will use them to do follow-up research.

The team compared Einstein's brain with those of 85 other humans already described in the scientific literature and found that the great physicist did indeed have something special between his ears. Although the brain, weighing 1230 grams, is only average in size, several regions feature additional convolutions and folds rarely seen in other subjects. For example, the regions on the left side of the brain that facilitate sensory inputs into, and motor control of, the face and tongue are much larger than normal; and his prefrontal cortex—linked to planning, focused attention, and perseverance in the face of challenges—is also greatly expanded.

"In each lobe," including the frontal, parietal, and occipital lobes, "there are regions that are exceptionally complicated in their convolutions," Falk says. As for the enlarged regions linked to the face and tongue, Falk thinks that this might relate to Einstein's famous quote that his thinking was often "muscular" rather than in words. Although this comment is usually interpreted as a metaphor for his subjective experiences as he thought about the universe, "it may be that he used his motor cortex in extraordinary ways" connected to abstract conceptualization, Falk says. Albert Galaburda, a neuroscientist at Harvard Medical School in Boston, says that "what's great about this paper is that it puts down … the entire anatomy of Einstein's brain in great detail." Nevertheless, Galaburda adds, the study raises "very important questions for which we don't have an answer." Among them are whether Einstein started off with a special brain that predisposed him to be a great physicist, or whether doing great physics caused certain parts of his brain to expand. Einstein's genius, Galaburda says, was probably due to "some combination of a special brain and the environment he lived in." And he suggests that researchers now attempt to compare Einstein's brain with that of other talented physicists to see if the brain's features were unique to Einstein himself or are also seen in other scientists.

Falk agrees that both nature and nurture were probably involved, pointing out that Einstein's parents were "very nurturing" and encouraged him to be independent and creative, not only in science but also in music, paying for piano and violin lessons. (Falk's 2009 study found that a brain region linked to musical talent was highly developed in Einstein's brain.)

"Einstein programmed his own brain," Falk says, adding that when the field of physics was ripe for new insights, "he had the right brain in the right place at the right time."

Edwin hubble

Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an American astronomer who played a crucial role in establishing the field of extragalactic astronomy and is generally regarded as one of the most important observational cosmologists of the 20th century. Hubble is generally mistakenly known for "Lemaître's law", discovered by Georges Lemaître, which is known more extensively as "Hubble's law". Hubble is also mistakenly credited with the discovery of the existence of galaxies other than the Milky Way, and with the galactic red shift discovery that the loss in frequency—the redshift—observed in the spectra of light from other galaxies increased in proportion to a particular galaxy's distance from Earth. This relationship became known as "Lemaître's law" or "Hubble's law". The existence of other galaxies and red shift was actually first discovered by the American astronomer Vesto Slipher. Using the data collected by Vesto Slipher and his (Hubble's) assistant Milton Humason (a former mule-driver and janitor), Hubble and Humason found a direct relationship between a galaxy's distance and its relative speed away from the solar system.

Hubble supported the Doppler shift interpretation of the observed redshift that had been proposed earlier by Vesto Slipher, and that led to the theory of the metric expansion of space. He tended to believe the frequency of any beam of light could, by some so far unknown means, be diminished ever stronger, the longer the beam travels through space.

Discoveries made by him:-

• The universe goes beyond the Milky Way galaxy
• Redshift increases with distance 

Awards

• Bruce Medal in 1938;
• Franklin Medal in 1939;
• Gold Medal of the Royal Astronomical Society in 1940;
• Legion of Merit for outstanding contribution to ballistics research in 1946.  

How to make Glow stick

Glow sticks give off light when two solutions are mixed. The sticks consist of a small, brittle container within a flexible outer container. Each container holds a unique solution. When the outer container is flexed, the inner container breaks, allowing the solutions to combine, causing the necessary chemical reaction. After breaking, the tube is shaken to thoroughly mix the two components.

Glow sticks contain hydrogen peroxide and phenol is produced as a byproduct. It is advisable to keep the mixture away from skin and to prevent accidental ingestion if the glow stick case splits or breaks. If spilled on skin, the chemicals could cause slight skin irritation, swelling, or, in extreme circumstances, vomiting and nausea. Some of the chemicals used in older glow sticks were thought to be potential carcinogens. The sensitizers used are polynuclear aromatic hydrocarbons, a class of compounds known for their carcinogenity.

 

New Plastics 'Bleed' When Cut or Scratched -- And Then Heal Like Human Skin

"Mother Nature has endowed all kinds of biological systems with the ability to repair themselves," explained Professor Marek W. Urban, Ph.D., who reported on the research. "Some we can see, like the skin healing and new bark forming in cuts on a tree trunk. Some are invisible, but help keep us alive and healthy, like the self-repair system that DNA uses to fix genetic damage to genes. Our new plastic tries to mimic nature, issuing a red signal when damaged and then renewing itself when exposed to visible light, temperature or pH changes."

Urban, who is with the University of Southern Mississippi in Hattiesburg foresees a wide range of potential applications for plastic with warn-and-self-repair capabilities. Scratches in automobile fenders, for instance, might be repaired by simply exposing the fender to intense light. Critical structural parts in aircraft might warn of damage by turning red along cracks so that engineers could decide whether to shine the light and heal the damage or undertake a complete replacement of the component. And there could be a range of applications in battlefield weapons systems.

Plastics have become so common, replacing steel, aluminum, glass, paper and other traditional materials because they combine desirable properties such as strength, light weight and corrosion resistance. Hundreds of scientists around the world have been working, however, to remedy one of the downsides of these ubiquitous materials: Once many plastics get scratched or cracked, repairs can be difficult or impossible.

Self-healing plastics have become a Holy Grail of materials science. One approach to that goal involves seeding plastics with capsules that break open when cracked or scratched and release repairing compounds that heal scratches or cuts. Another is to make plastics that respond to an outside stimulus -- like light, heat or a chemical agent -- by repairing themselves.

Urban's group developed plastics with small molecular links or "bridges" that span the long chains of chemicals that compose plastic. When plastic is scratched or cracked, these links break and change shape. Urban tweaked them so that changes in shape produce a visible color change -- a red splotch that forms around the defect. In the presence of ordinary sunlight or visible light from a light bulb, pH changes or temperature, the bridges reform, healing the damage and erasing the red mark.

Urban cited other advantages of the new plastic. Unlike self-healing plastics that rely on embedded healing compounds that can self-repair only once, this plastic can heal itself over and over again. The material also is more environmentally friendly than many other plastics, with the process for producing the plastic water-based, rather than relying on potentially toxic ingredients. And his team now is working on incorporating the technology into plastics that can withstand high temperatures.

Making a Better Invisibility Cloak

These new findings could be important in transforming how light or other waves can be controlled or transmitted. Just as traditional wires gave way to fiber optics, the new meta-material could revolutionize the transmission of light and waves.Because the goal of this type of research involves taming light, a new field of transformational optics has emerged. The results of the Duke experiments were published online Nov. 11 in the journal Nature Materials.The Duke team has extensive experience in creating "meta-materials," human-made objects that have properties often absent in natural ones. Structures incorporating meta-materials can be designed to guide electromagnetic waves around an object, only to have them emerge on the other side as if they had passed through an empty volume of space, thereby cloaking the object.

"In order to create the first cloaks, many approximations had to be made in order to fabricate the intricate meta-materials used in the device," said Nathan Landy, a graduate student working in the laboratory of senior investigator David R. Smith, William Bevan Professor of electrical and computer engineering at Duke's Pratt School of Engineering.

"One issue, which we were fully aware of, was loss of the waves due to reflections at the boundaries of the device," Landy said. He explained that it was much like reflections seen on clear glass. The viewer can see through the glass just fine, but at the same time the viewer is aware the glass is present due to light reflected from the surface of the glass. "Since the goal was to demonstrate the basic principles of cloaking, we didn't worry about these reflections."

Landy has now reduced the occurrence of reflections by using a different fabrication strategy. The original cloak consisted of parallel and intersecting strips of fiberglass etched with copper. Landy's cloak used a similar row-by-row design, but added copper strips to create a more complicated -- and better performing -- material. The strips of the device, which is about two-feet square, form a diamond-shape, with the center left empty.

When any type of wave, like light, strikes a surface, it can be either reflected or absorbed, or a combination of both. In the case of earlier cloaking experiments, a small percentage of the energy in the waves was absorbed, but not enough to affect the overall functioning of the cloak.

The cloak was naturally divided into four quadrants. Landy explained the "reflections" noted in earlier cloaks tended to occur along the edges and corners of the spaces within and around the meta-material.

"Each quadrant of the cloak tended to have voids, or blind spots, at their intersections and corners with each other," Landy said. "After many calculations, we thought we could correct this situation by shifting each strip so that it met its mirror image at each interface.

"We built the cloak, and it worked," he said. "It split light into two waves which traveled around an object in the center and re-emerged as the single wave with minimal loss due to reflections."

Landy said this approach could have more applications than just cloaks. For example, meta-materials can "smooth out" twists and turns in fiber optics, in essence making them seem straighter. This is important, Landy said, because each bend attenuates the wave within it.

The researchers are now working to apply the principles learned in the latest experiments to three dimensions, a much greater challenge than in a two-dimensional device.

Unique Spinal Nerve Cell Activity: Novel Forms of Activity Linked to Development of Motor Behaviors Such as Swimming

The breakthrough in the Department of Biology at the University of Leicester was announced Nov 8 in the journal Current Biology.

Although the neural basis of motor control has been studied for over a century, the processes controlling maturation of locomotor behaviours -- like walking and swimming -- are not fully understood.The University of Leicester research into nerve cells responsible for motor behaviours was carried out on fish. The team aimed to understand how spinal networks produce rhythmic activity from a very immature stage -- and how such activity changes during maturation.

The team used zebrafish, a freshwater fish native to northern India and Bangladesh, because their motor networks are similar to humans. However, as they are fertilized outside the mother and their embryos are transparent, scientists can readily monitor motor network development from its onset -- something that is very difficult to do in mammals.

Lecturer in Neurobiology, Dr Jonathan McDearmid, who led the research, said: "What's unique about our work is the observation that a group of spinal nerve cells generate unusual forms of electrical activity that adapt to meet the changing requirements of the developing motor network. Whilst these cells had been previously identified, their excitable properties had not been studied in detail. We found that these cells produce age-specific activity patterns: in early life they have "autorhythmic" properties that are likely to drive embryonic movements. However, as fish develop towards more mature swimming stages, they switch firing activity to generate sustained impulses that appear to be necessary for maintenance of swimming.

"Our work is important because it sheds light on the mechanisms by which spinal nerve cells shape activity in the maturing of motor network. This is basic research that allows us to better understand how vertebrate motor activity emerges. However, in the long term, understanding of this process might help determine what goes wrong in diseases that affect spinal cord function."

Dr McDearmid said the identification of the activity generated by this group of cells -termed IC cells- happened as quite a surprise: "It was two days after Christmas when we first observed IC cells generating these unusual patterns of activity. I was conducting a few routine experiments for a related study we were running in parallel. Whilst monitoring electrical responses in different nerve cells I hit on a cell that did some very unusual things. It was a very exciting finding indeed. The only problem was that subsequent attempts to find this "magic cell" didn't prove straightforward. Because these cells change location as the fish develops, it initially proved challenging to track them down for further study. Still, in time we figured out where these cells were and that very first recording turned out to be one of the best Christmas presents we've ever had."

Researchers say they have a long way yet to go in the study -- and many questions remain unanswered. Dr McDearmid said: "We have many questions that we want to ask next. Are there other cells in the developing spine that display similar types of activity? Also, we currently have no idea how IC cells function at more mature stages, such as in adult fish. Our next aim is to determine whether IC cells retain their unusual firing characteristics at older stages."

Seceret of success

What is success? Success is when you bask the glory. It is definitely success when you are getting some remarkable results. How to become a successful person? I do believe there are three important things: to know definition of your purpose, to know what your goals is and have a burning desire to accomplish that goals.

Do you know, what is your pre-encoded purpose? It is simple to know it from your context. E.g. if you handle something well and like to do it the most, it seems that it is your purpose to do it. If you still have not found your purpose, seize any opportunities to try something different from what you do everyday. If you find it, you will know and can loudly say to yourself: “This is my purpose to do this”. You can also refer to method proposed by Steve Pavlina in post “How to discover your life purpose in about 20 minutes” – I have tried it, and it works! Write down your propose and refer anytime you are setting goals and doing important decisions.

Do you know exactly what you want? What do you want to achieve in 5 years? How do you imagine yourself in one year? What will you do, if you know that in 6 months a thunderbolt will kill you? Is it the same thing which you are doing right now? If it is not so, you have to change your life. Set yourself a target you want to achieve and start going right now! You can refer to “How to Set Goals” manual at wikiHow. And even if you are not certain about is it the best target you can set or not – set it anyway. To have any goal set by yourself is better that not to set anything. If you do not do this, somebody else, like your boss, friend, partner, stranger or society will do it for you.

When you know your purpose and you have set a goal, do not procrastinate – do it now! Don’t play it safe, every day take any chance to move to your target. Imagine how you will feel, when you achieve it. Everyone should see a fire in your eyes. Feed yourself with motivation material, like this post, every morning on breakfast – and success will come. You can inspire youself by ideas from article “Cultivating Burning Desire“.
So if you want to be a successful person – now you know what to do. If it is still not clear – possibly you have to reread this again . Do it now!

World's Rarest Whale Seen for the First Time

The discovery is the first evidence that this whale is still with us and serves as a reminder of just how little we still know about life in the ocean, the researchers say. The findings also highlight the importance of DNA typing and reference collections for the identification of rare species.

"This is the first time this species -- a whale over five meters in length -- has ever been seen as a complete specimen, and we were lucky enough to find two of them," says Rochelle Constantine of the University of Auckland. "Up until now, all we have known about the spade-toothed beaked whale was from three partial skulls collected from New Zealand and Chile over a 140-year period. It is remarkable that we know almost nothing about such a large mammal."

The two whales were discovered in December 2010, when they live-stranded and subsequently died on Opape Beach, New Zealand. The New Zealand Department of Conservation was called to the scene, where they photographed the animals and collected measurements and tissue samples.

The whales were initially identified not as spade-toothed beaked whales but as much more common Gray's beaked whales. Their true identity came to light only following DNA analysis, which is done routinely as part of a 20-year program to collect data on the 13 species of beaked whales found in New Zealand waters.

"When these specimens came to our lab, we extracted the DNA as we usually do for samples like these, and we were very surprised to find that they were spade-toothed beaked whales," Constantine says. "We ran the samples a few times to make sure before we told everyone."

The researchers say they really have no idea why the whales have remained so elusive.

"It may be that they are simply an offshore species that lives and dies in the deep ocean waters and only rarely wash ashore," Constantine says. "New Zealand is surrounded by massive oceans. There is a lot of marine life that remains unknown to us."

In-Sync Brain Waves Hold Memory of Objects Just Seen

Charles Gray, Ph.D., of Montana State University, Bozeman, a grantee of NIH's National Institute of Mental Health (NIMH), and colleagues, report their findings Nov. 1, 2012, online, in the journal Science Express.

"This work demonstrates, for the first time, that there is information about short term memories reflected in in-sync brainwaves," explained Gray.

"The Holy Grail of neuroscience has been to understand how and where information is encoded in the brain. This study provides more evidence that large scale electrical oscillations across distant brain regions may carry information for visual memories," said NIMH director Thomas R. Insel, M.D.

Prior to the study, scientists had observed synchronous patterns of electrical activity between the two circuit hubs after a monkey saw an object, but weren't sure if the signals actually represent such short-term visual memories in the brain. Rather, it was thought that such neural oscillations might play the role of a traffic cop, directing information along brain highways.

To find out more, Gray, Rodrigo Salazar Ph.D., and Nick Dotson of Montana State and Steven Bressler, Ph.D., at Florida Atlantic University, Boca Raton, recorded electrical signals from groups of neurons in both hubs of two monkeys performing a visual working memory task. To earn a reward, the monkeys had to remember an object -- or its location -- that they saw momentarily on a computer screen and correctly match it. The researchers expected to see the telltale boost in synchrony during a delay period immediately after an object disappeared from the screen, when the monkey had to hold information briefly in mind.

The degree of synchronous activity, or coherence, between cells in the areas was plotted for different objects the monkeys saw.

Brain waves of many neurons in the two hubs, called the prefrontal cortex and posterior parietal cortex, synchronized to varying degrees -- depending on an object's identity (see picture below). This and other evidence indicated that neurons in these hubs are selective for particular features in the visual field and that synchronization in the circuit carries content-specific information that might contribute to visual working memory.

The researchers also determined that the parietal cortex was more influential than the prefrontal cortex in driving this process. Previously, many researchers had thought that the firing rate of single neurons in the prefrontal cortex, the brain's executive, is the major player in working memory.

Since synchronized oscillations between populations of cells distinguished between visual stimuli, it's theoretically possible to determine the correct answers for the matching tasks the monkeys performed simply by reading their brain waves. Similarly, synchrony between cell populations in the two hubs also distinguished between locations. So the location of visual information, like object identity, also appears to be represented by synchronous brain waves. Again, researchers previously thought that these functions had mostly to do with the firing rates of neurons.

So the new findings may upturn prevailing theory.

Tabletop Fault Model Reveals Why Some Earthquakes Result in Faster Shaking

"The high frequency waves of an earthquake -- the kind that produces the rapid jolts -- are not well understood because they are more difficult to measure and more difficult to model," said study lead author Gregory McLaskey, a former UC Berkeley Ph.D. student in civil and environmental engineering. "But those high frequency waves are what matter most when it comes to bringing down buildings, roads and bridges, so it's important for us to understand them."    

While the study, to be published in the Nov. 1 issue of the journal Natureand funded by the National Science Foundation, does nothing to bring scientists closer to predicting when the next big one will hit, the findings could help engineers better assess the vulnerabilities of buildings, bridges and other structures when a fault does rupture.

"The experiment in our lab allows us to consider how long a fault has healed and more accurately predict the type of shaking that would occur when it ruptures," said Steven Glaser, UC Berkeley professor of civil and environmental engineering and principal investigator of the study. "That's important in improving building designs and developing plans to mitigate for possible damage."

To create a fault model, the researchers placed a Plexiglas slider block against a larger base plate and equipped the system with sensors. The design allowed the researchers to isolate the physical and mechanical factors, such as friction, that influence how the ground will shake when a fault ruptures.

It would be impossible to do such a detailed study on faults that lie several miles below the surface of the ground, the authors said. And current instruments are generally unable to accurately measure waves at frequencies higher than approximately 100 Hertz because they get absorbed by the earth.

"There are many people studying the properties of friction in the lab, and there are many others studying the ground motion of earthquakes in the field by measuring the waves generated when a fault ruptures," said McLaskey. "What this study does for the first time is link those two phenomena. It's the first clear comparison between real earthquakes and lab quakes."

Noting that fault surfaces are not smooth, the researchers roughened the surface of the Plexiglas used in the lab's model.

"It's like putting two mountain ranges together, and only the tallest peaks are touching," said McLaskey, who is now a postdoctoral researcher with the U.S. Geological Survey in Menlo Park.

As the sides "heal" and press together, the researchers found that individual contact points slip and transfer the resulting energy to other contact points.

"As the pressing continues and more contacts slip, the stress is transferred to other contact points in a chain reaction until even the strongest contacts fail, releasing the stored energy as an earthquake," said Glaser. "The longer the fault healed before rupture, the more rapidly the surface vibrated."

"It is elegant work," said seismologist John Vidale, a professor at the University of Washington who was not associated with the study. "The point that more healed faults can be more destructive is dismaying. It may not be enough to locate faults to assess danger, but rather knowing their history, which is often unknowable, that is key to fully assessing their threat."

Glaser and McLaskey teamed up with Amanda Thomas, a UC Berkeley graduate student in earth and planetary sciences, and Robert Nadeau, a research scientist at the Berkeley Seismological Laboratory, to confirm that their lab scenarios played out in the field. The researchers used records of repeating earthquakes along the San Andreas fault that Nadeau developed and maintained. The data were from Parkfield, Calif., an area which has experienced a series of magnitude 6.0 earthquakes two to three decades apart over the past 150 years.

Thomas and McLaskey explored the records of very small, otherwise identically repeating earthquakes at Parkfield to show that the quakes produced shaking patterns that changed depending on the time span since the last event, just as predicted by the lab experiments.

In the years after a magnitude 6.0 earthquake hit Parkfield in 2004, the small repeating earthquakes recurred more frequently on the same fault patches.

"Immediately after the 2004 Parkfield earthquake, many nearby earthquakes that normally recurred months or years apart instead repeated once every few days before decaying back to their normal rates," said Thomas. "Measurements of the ground motion generated from each of the small earthquakes confirmed that the shaking is faster when the time from the last rupture increases. This provided an excellent opportunity to verify that ground motions observed on natural faults are similar to those observed in the laboratory, suggesting that a common underlying mechanism -- fault healing -- may be responsible for both."

Understanding how forcefully the ground will move when an earthquake hits has been one of the biggest challenges in earthquake science.

"What makes this study special is the combination of lab work and observations in the field," added Roland Burgmann, a UC Berkeley professor of earth and planetary sciences who reviewed the study but did not participate in the research. "This study tells us something fundamental about how earthquake faults evolve. And the study suggests that, in fact, the lab setting is able to capture some of those processes correctly."

Glaser said the next steps in his lab involve measuring the seismic energy that comes from the movement of the individual contact points in the model fault to more precisely map the distribution of stress and how it changes in the run-up to a laboratory earthquake event.