Category Archives: energy

Our Universe at Home Within a Larger Universe? So Says Physicist’s Wormhole Research!

Such a scenario in which the universe is born from inside a wormhole (also called an Einstein-Rosen Bridge) is suggested in a paper from Indiana University theoretical physicist Nikodem Poplawski in Physics Letters B. The final version of the paper was available online March 29 and will be published in the journal edition April 12.

Poplawski takes advantage of the Euclidean-based coordinate system called isotropic coordinates to describe the gravitational field of a black hole and to model the radial geodesic motion of a massive particle into a black hole.

In studying the radial motion through the event horizon (a black hole’s boundary) of two different types of black holes — Schwarzschild and Einstein-Rosen, both of which are mathematically legitimate solutions of general relativity — Poplawski admits that only experiment or observation can reveal the motion of a particle falling into an actual black hole. But he also notes that since observers can only see the outside of the black hole, the interior cannot be observed unless an observer enters or resides within.

“This condition would be satisfied if our universe were the interior of a black hole existing in a bigger universe,” he said. “Because Einstein’s general theory of relativity does not choose a time orientation, if a black hole can form from the gravitational collapse of matter through an event horizon in the future then the reverse process is also possible. Such a process would describe an exploding white hole: matter emerging from an event horizon in the past, like the expanding universe.”

A white hole is connected to a black hole by an Einstein-Rosen bridge (wormhole) and is hypothetically the time reversal of a black hole. Poplawski’s paper suggests that all astrophysical black holes, not just Schwarzschild and Einstein-Rosen black holes, may have Einstein-Rosen bridges, each with a new universe inside that formed simultaneously with the black hole.

“From that it follows that our universe could have itself formed from inside a black hole existing inside another universe,” he said.

By continuing to study the gravitational collapse of a sphere of dust in isotropic coordinates, and by applying the current research to other types of black holes, views where the universe is born from the interior of an Einstein-Rosen black hole could avoid problems seen by scientists with the Big Bang theory and the black hole information loss problem which claims all information about matter is lost as it goes over the event horizon (in turn defying the laws of quantum physics).

This model in isotropic coordinates of the universe as a black hole could explain the origin of cosmic inflation, Poplawski theorizes.

Poplawski is a research associate in the IU Department of Physics. He holds an M.S. and a Ph.D. in physics from Indiana University and a M.S. in astronomy from the University of Warsaw, Poland.

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Multiplying Universes: How Many Is The Multiverse? – New Scientist

Multiplying universes: How many is the multiverse? – space – 28 October 2009 – New Scientist.

HOW many universes are there? Cosmologists Andrei Linde and Vitaly Vanchurin at Stanford University in California calculate that the number dwarfs the 10500 universes postulated in string theory, and raise the provocative notion that the answer may depend on the human brain.

The idea that there is more than one universe, each with its own laws of physics, arises out of several different theories, including string theory and cosmic inflation. This concept of a “multiverse” could explain a puzzling mystery – why dark energy, the furtive force that is accelerating the expansion of space, appears improbably fine-tuned for life. With a large number of universes, there is bound to be one that has a dark energy value like ours.

Calculating the probability of observing this value – and other features of the cosmos – depends on how many universes of various kinds populate the multiverse. String theory describes 10500 universes, but that just counts different vacuum states, which are like the blank canvases upon which universes are painted. The features of each canvas determine what the overall painting will look like – such as the laws of physics in that universe – but not the details.

Thanks to the randomness of quantum mechanics, two identical vacuum states can end up as very different universes. Small quantum fluctuations in the very early universe are stretched to astronomical scales by inflation, the period of faster-than-light expansion just after the big bang. These fluctuations lay down a gravitational blueprint that eventually determines the placement of stars and galaxies across the sky. Small differences in the form of these fluctuations can produce a universe in which the Milky Way is slightly bigger, or closer to its neighbours.

So just how many of these different universes can inflation’s quantum fluctuations produce? According to Linde and Vanchurin, the total is about 101010,000,000 – that’s a 10 raised to a number ending with 10 million zeros (arxiv.org/abs/0910.1589). Suddenly string theory’s multiverse of 10500universes is looking rather claustrophobic.

It might be, however, that this number is irrelevant, and that in a world ruled by quantum physics what matters is how many universes a single observer can distinguish. “Before quantum mechanics,” says Linde, “we thought that ‘reality’ was a well-defined word.” In classical physics, observers are irrelevant – we simply want to know how many universes exist.

It may not matter how many universes exist – just how many a single observer can tell apart

According to quantum physics, observers affect the systems they measure(see “Restricted view”). If observers are an integral part of the cosmic formula, then it may not matter how many universes exist – just how many a single observer can tell apart. If the observer is a person, that depends on how many bits of information the brain can process. “Based on the number of synapses in a typical brain, a human observer can register 1016,” says Linde. That means humans can differentiate 101016 universes, which is much more manageable than the 101010,000,000 Linde and Vanchurin found to start with.

But does the human brain really play a role in making predictions in the multiverse? “This goes deep into philosophy,” Linde says. “It’s a slippery slope.”

Cosmologist Alex Vilenkin of Tufts University in Boston is equally ambivalent. “It could be right that what is important is what an observer sees,” he says. “But there might be things an observer doesn’t see that are still there.”

Restricted view

Quantum theory splits the world into two parts: the system under study and the rest of the world, which contains the observer. The system hovers in a ghostly state of near-existence made up of a host of possibilities until the observer makes a measurement – and so reduces this to a single reality.

Cosmology suffers from the paradox that no observer can be outside the universe – so the universe is doomed to spend eternity as nothing more than a vague possibility. The lesson of quantum cosmology is that we can’t talk about the universe as a whole, but only what a given observer inside it might measure. Applying that lesson to the multiverse, Andrei Linde and Vitaly Vanchurin suggest that what matters is not the total number of possible universes, but the number of universes a single observer could distinguish.

If that observer is a human, the brain limits the amount of information they can register. But any observer – even an inanimate one such as a galaxy – is limited in the information it can store. These limitations in what observers can measure whittle down the number of universes that come into play in cosmological predictions. That means an observer might make a difference in explaining the value of things like dark energy.

Rethinking relativity: Is time out of joint? – space – 21 October 2009 – New Scientist

EVER since Arthur Eddington travelled to the island of Príncipe off Africa to measure starlight bending around the sun during a 1919 eclipse, evidence for Einstein’s theory of general relativity has only become stronger. Could it now be that starlight from distant galaxies is illuminating cracks in the theory’s foundation?

Everything from the concept of the black hole to GPS timing owes a debt to the theory of general relativity, which describes how gravity arises from the geometry of space and time. The sun’s gravitational field, for instance, bends starlight passing nearby because its mass is warping the surrounding space-time. This theory has held up to precision tests in the solar system and beyond, and has explained everything from the odd orbit of Mercury to the way pairs of neutron stars perform their pas de deux.

Yet it is still not clear how well general relativity holds up over cosmic scales, at distances much larger than the span of single galaxies. Now the first, tentative hint of a deviation from general relativity has been found. While the evidence is far from watertight, if confirmed by bigger surveys, it may indicate either that Einstein’s theory is incomplete, or else that dark energy, the stuff thought to be accelerating the expansion of the universe, is much weirder than we thought(see “Not dark energy, dark fluid”).

The analysis of starlight data by cosmologist Rachel Bean of Cornell University in Ithaca, New York, has generated quite a stir. Shortly after the paper waspublished on the pre-print physics archive, prominent physicist Sean Carroll of the California Institute of Technology in Pasadena praised Bean’s research. “This is serious work by a respected cosmologist,” he wrote on his blog Cosmic Variance. “Either the result is wrong, and we should be working hard to find out why, or it’s right, and we’re on the cusp of a revolution.”

If it is wrong, we should be working hard to find out why, but if it’s right, we are on the cusp of a revolution

“It has caused quite a furore in astronomy circles,” says Richard Massey of the Royal Observatory Edinburgh in the UK. “This paper has generated a lot of interest.”

Bean found her evidence lurking in existing data collected by the Cosmic Evolution Survey, a multi-telescope imaging project that includes the longest survey yet by the Hubble Space Telescope. COSMOS, which detected more than 2 million galaxies over a small patch of sky, takes advantage of gravity’s ability to bend light. Massive objects like galaxy clusters bend the light of more distant objects so that it is directed towards or away from Earth. This effect, called gravitational lensing, is at its most dramatic when it creates kaleidoscopic effects like luminous rings or the appearance of multiple copies of a galaxy.

The sky is also dominated by the distorting effects of “weak lensing”, in which intervening matter bends light to subtly alter the shapes and orientations of more distant galaxies, creating an effect similar to that of looking through old window glass. Since galaxies come in all shapes and sizes, it is difficult to know whether the light from an individual galaxy has been distorted, because there is nothing to compare it with. But by looking for common factors in the distortion of many galaxies, it is possible to build up a map of both the visible and even unseen matterMovie Camera that bend their light.

The weak lensing technique can also be used to measure two different effects of gravity. General relativity calls for gravity’s curvature of space to be equivalent to its curvature of time. Light should be influenced in equal amounts by both.

When the COSMOS data was released in 2007, the team – led by Massey – assumed these two factors were equivalent. Their analysis revealed that gravitational tugs on light were stronger than anticipated, but they put this down to a slightly higher concentration of ordinary and dark matter in the survey’s patch of sky than had been predicted.

To look for potential deviations from general relativity, Bean reanalysed the data and dropped the requirement that these two components of gravity had to be equal. Instead the ratio of the two was allowed to change in value. She found that between 8 and 11 billion years ago gravity’s distortion of time appeared to be three times as strong as its ability to curve space. An observer around at the time wouldn’t have noticed the effect because it only applies over large distances. Nonetheless, “there is a preference for a significant deviation from general relativity”, says Bean (www.arxiv.org/abs/0909.3853).

Gravity’s distortion of time appeared to be three times as strong as its ability to curve space

At this stage, it’s hard to say what would happen if the deviation from general relativity was confirmed. Cosmologists have already considered some modifications to general relativity that could explain the universe’s acceleration(see “Not dark energy, dark fluid”).

Yet finding a deviation when the universe was less than half its current age is odd – if general relativity had broken down at some level, the signs should be most dramatic more recently, long after the repulsive effect of dark energy overwhelmed the attractive powers of gravity some 6 billion years ago.

Most astronomers, including Bean, are cautious about the results. “Nobody is yet betting money that the effect is real,” says cosmologist Dragan Huterer of the University of Michigan in Ann Arbor. Various other explanations, like a bias in the technique used to estimate the distances to galaxies, now need to be ruled out.

Although COSMOS photographed a deep patch of sky, it was fairly small by the standards of modern surveys. This opens up the possibility that this region might be anomalous, notes Asantha Cooray, an astrophysicist at the University of California, Irvine. “You could have a massive galaxy cluster that could boost your weak lensing signal up. Or by random chance you could have more dark matter,” says Cooray, part of a team that analysed other survey data taken with the Canada-France-Hawaii Telescope in Hawaii and found no hint of a departure from general relativity. “The only way to take that into account is to look at data in a larger field.”

Future projects will scan the sky over much wider areas and collect images of many more lensed galaxies. For example, the Dark Energy Survey is poised to start surveying the sky from 2011 and will build up an even more precise picture of how light has been bent over the course of the universe’s history.

Whether these surveys find the effect or not, Bean hopes that her paper will generate more interest in the idea of using weak lensing to test general relativity. “I’m not putting my flag out there and saying this is a real thing,” Bean says. “We need to look at more data sets. This is really just the first stage for trying to test gravity in this way.”

Massey agrees: “At the moment we’re in the mode of just trying to hack into general relativity to find the chinks in its armour, to find any places where it might not be working.” n

Not dark energy, dark fluid

Dark energy could be weirder than we thought. Evidence that over large distances gravity exerts a greater pull on time than on space (see main story) might not necessarily suggest that the theory of general relativity is wrong. It could instead be a sign that the universe’s acceleration may require a more exotic explanation.

The simplest way of explaining the universe’s acceleration is to invoke a cosmological constant, originally proposed by Einstein to allow the universe to remain the same size in the presence of matter. This describes a universe filled with uniform, outward-pushing energy. But there are other possible explanations for acceleration.

One idea is that the entire universe exists on a membrane, or brane, floating inside an extra dimension. While matter will be confined to three dimensions, gravity could be leaking into this extra dimension. When the universe becomes large enough, this gravity could interact with matter in the brane, to produce acceleration on large scales.

A deviation could also be a sign that dark energy is a more complex “fluid” that exerts varying pressures in different directions. The snag is that telling the difference between a more exotic form of dark energy and a modification to our understanding of gravity could be tricky.

“If we were to detect a departure,” says cosmologist Alessandra Silvestriof the Massachusetts Institute of Technology, we might not be able to tell whether there is a flaw in general relativity or just evidence that dark energy is “some sort of fancy fluid”.

Cold Fusion or sequel to ‘The Saint’?

 

coldfusionWASHINGTON (AFP) – Researchers at a US Navy laboratory have unveiled what they say is “significant” evidence of cold fusion, apotential energy source that has many skeptics in the scientific community.

The scientists on Monday described what they called the first clear visual evidence that low-energy nuclear reaction (LENR), or cold fusion devices can produce neutrons, subatomic particles that scientists say are indicative of nuclear reactions.

“Our finding is very significant,” said analytical chemist Pamela Mosier-Boss of the US Navy’s Space and Naval Warfare Systems Center (SPAWAR) in San Diego, California.

“To our knowledge, this is the first scientific report of the production of highly energetic neutrons from a LENR device,” added the study’s co-author in a statement. The study’s results were presented at the annual meeting of theAmerican Chemical Society in Salt Lake City, Utah. The city is also the site of an infamous presentation on cold fusion 20 years ago by Martin Fleishmann and Stanley Pons that sent shockwaves across the world.

coldfusion_timeDespite their claim to cold fusion discovery, the Fleishmann-Pons study soon fell into discredit after other researchers were unable to reproduce the results. Scientists have been working for years to produce cold fusion reactions, a potentially cheap, limitless and environmentally-clean source of energy.

Paul Padley, a physicist at Rice University who reviewed Mosier-Boss’s published work, said the study did not provide a plausible explanation of how cold fusion could take place in the conditions described.

“It fails to provide a theoretical rationale to explain how fusion could occur at room temperatures. And in its analysis, the research paper fails to exclude other sources for the production of neutrons,” he told the Houston Chronicle.

“The whole point of fusion is, you?re bringing things of like charge together. As we all know, like things repel, and you have to overcome that repulsion somehow.”

But Steven Krivit, editor of the New Energy Times, said the study was “big” and could open a new scientific field. The neutrons produced in the experiments “may not be caused by fusion but perhaps some new, unknown nuclear process,” added Krivit, who has monitored cold fusion studies for the past 20 years.

“We’re talking about a new field of science that’s a hybrid between chemistry and physics.”

There’s Nothing to See Here!!

Science closing in on cloak of invisibility

WASHINGTON – They can’t match Harry Potter yet, but scientists are moving closer to creating a real cloak of invisibility.

Researchers at Duke University, who developed a material that can “cloak” an item from detection by microwaves, report that they have expanded the number of wavelengths they can block.
In 2006 the team reported they had developed so-called metamaterials that could deflect microwaves around a three-dimensional object, essentially making it invisible to the waves.
The system works like a mirage, where heat causes the bending of light rays and cloaks the road ahead behind an image of the sky.

The researchers report in Thursday’s edition of the journal Science that they have developed a series of mathematical commands to guide the development of more types of metamaterials to cloak objects from an increasing range of electromagnetic waves.
“The new device can cloak a much wider spectrum of waves — nearly limitless — and will scale far more easily to infrared and visible light. The approach we used should help us expand and improve our abilities to cloak different types of waves,” senior researcher David R. Smith said in a statement.

The new cloak is made up of more than 10,000 individual pieces of fiberglass arranged in parallel rows. The mathematical formulas are used to determine the shape and placement of each piece to deflect the electromagnetic waves.

Science.com

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