Posts tagged astrophysics.

we-are-star-stuff:

The Alternate Realities of the Multiverse

We tend to focus on major decisions as having momentous effects, but what if something as simple as a missed train could change the course of your life? And what if you follow two different paths to see which turned out better?

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thenewenlightenmentage:

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thenewenlightenmentage:

The “Dark Flow” & the Existence of Other Universes —New Claims of Hard Evidence

Is our universe merely one of billions? Evidence of the existence of ‘multiverse’ revealed for the first time by a cosmic map of background radiation data gathered by Planck telescope. This past week, the first ‘hard evidence’ that other universes exist has been claimed to have been found by cosmologists studying the Planck data. They have concluded that it shows anomalies that can only have been caused by the gravitational pull of other universes.

“Such ideas may sound wacky now, just like the Big Bang theory did three generations ago,” says George Efstathiou, professor of astrophysics at Cambridge University.”But then we got evidence and now it has changed the whole way we think about the universe.”

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Earth may be crashing through dark matter walls ›

abluegirl:

Pospelov and colleagues have been examining a theory that at least some of the universe’s dark matter is tied up in structures called domain walls, akin to the boundaries between tightly packed bubbles. The idea is that the hot early universe was full of an exotic force field that varied randomly. As the universe expanded and cooled, the field froze, leaving a patchwork of domains, each with its own distinct value for the field.

Having different fields sit next to each other requires energy to be stored within the domain walls. Mass and energy are interchangeable, so on a large scale a network of domain walls can look like concentrations of mass – that is, like dark matter, says Pospelov.

If the grid of domain walls is packed tightly enough – say, if the width of the domains is several hundred times the distance between Earth and the sun – Earth should pass through a domain wall once every few years. “As a human, you wouldn’t feel a thing,” says Pospelov. “You will go through the wall without noticing.” But magnetometers – devices that, as the name suggests, measure magnetic fields – could detect the walls, say Pospelov and colleagues in a new study. Although the field inside a domain would not affect a magnetometer, the device would sense the change when Earth passes through a domain wall.

Dark matter walls have not been detected yet because anyone using a single magnetometer would find the readings swamped by noise, Pospelov says. “You’d never be able to say if it’s because the Earth went through a bizarre magnetic field or if a grad student dropped their iPhone or something,” he says

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ikenbot:

Are We Living Inside a Computer Simulation?

The popular film trilogy, The Matrix, presented a cyberuniverse where humans live in a simulated reality created by sentient machines.

Now, a philosopher and team of physicists imagine that we might really be living inside a computer-generated universe that you could call The Lattice. What’s more, we may be able to detect it.

In 2003, British philosopher Nick Bostrom published a paper that proposed the universe we live in might in fact really be a numerical computer simulation. To give this a bizarre Twilight Zone twist, he suggested that our far-evolved distant descendants might construct such a program to simulate the past and recreate how their remote ancestors lived.

He felt that such an experiment was inevitable for a supercivilization. If it didn’t happen by now, then in meant that humanity never evolved that far and we’re doomed to a short lifespan as a species, he argued.

To extrapolate further, I’d suggest that artificial intelligent entities descended from us would be curious about looking back in time by simulating the universe of their biological ancestors.

As off-the-wall as this sounds, a team of physicists at the University of Washington (UW) recently announced that there is a potential test to seen if we actually live in The Lattice. Ironically, it would be the first such observation for scientifically hypothesized evidence of intelligent design behind the cosmos.

The UW team too propose that super-intelligent entities, bored with their current universe, do numerical simulations to explore all possibilities in the landscape of the underlying quantum vacuum (from which the big bang percolated) through universe simulations. “This is perhaps the most profound quest that can be undertaken by a sentient being,” write the authors.

Before you dismiss this idea as completely loony, the reality of such a Sim Universe might solve a lot of eerie mysteries about the cosmos. About two-dozen of the universe’s fundamental constants happen to fall within the narrow range thought to be compatible with life. At first glance it seems as unlikely as balancing a pencil on its tip. Jiggle these parameters and life as we know it would have never appeared. Not even stars and galaxies. This is called the Anthropic principle.

ANALYSIS: Building the Universe Inside a Supercomputer

The discovery of dark energy over a decade ago further compounds the universe’s strangeness. This sort of “antigravity” pushing space-time apart is the closest thing there is to nothing and still is something. This energy from the vacuum of space is 60 orders of magnitude weaker that what would be predicted by quantum physics.The eminent cosmologist Michael Turner ranks dark energy as “the most profound mystery in all of science.”

We are also living at a very special time in the universe’s history where it switched gears from decelerating to accelerating under the push of dark energy. This begs the question “why me why now?” (A phrase popularly attributed to Olympic figure skater Nancy Kerrigan in 1994 when she was attacked and crippled by an opponent.)

If dark energy were slightly stronger the universe would have blown apart before stars formed. Any weaker and the universe would have imploded long ago. Its incredibly anemic value has been seen as circumstantial evidence for parallel universes with their own flavor of dark energy that is typically destructive. It’s as if our universe won the lottery and got all the physical parameters just right for us to exist.

Finally, an artificial universe solves the Fermi Paradox (where are all the space aliens?) by implying that we truly are alone in the universe. It was custom made for us by our far-future progeny.

Biblical creationists can no doubt embrace these seeming cosmic coincidences as unequivocal evidence for their “theory” of Intelligent Design (ID). But is our “God” really a computer programmer rather than a bearded old man living in the sky?

Currently, supercomputers using a impressive-sounding technique called lattice quantum chromodynamics, and starting from the fundamental physical laws, can simulate only a very small portion of the universe. The scale is a little larger than the nucleus of an atom, according UW physicist Martin Savage. Mega-computers of the far future could greatly expand the size of the Sim Universe.

ANALYSIS: Artificial Universe Created Inside a Supercomputer

If we are living in such a program, there could be telltale evidence for the underlying lattice used in modeling the space-time continuum, say the researchers. This signature could show up as a limitation in the energy of cosmic rays. They would travel diagonally across the model universe and not interact equally in all directions, as they otherwise would be expected to do according to present cosmology.

If such results were measured, physicists would have to rule out any and all other natural explanations for the anomaly before flirting with the idea of intelligent design. (To avoid confusion with the purely faith-based creationist ID, this would not prove the existence of a biblical God, because you’d have to ask the question “why does God need a lattice?”)

If our universe is a simulation, then those entities controlling it could be running other simulations as well to create other universes parallel to our own. No doubt this would call for, ahem, massive parallel processing.

If all of this isn’t mind-blowing enough, Bostrom imagined “stacked” levels of reality, “we would have to suspect that the post-humans running our simulation are themselves simulated beings; and their creators, in turn, may also be simulated beings. Here may be room for a large number of levels of reality, and the number could be increasing over time.”

To compound this even further, Bostrom imagined a hierarchy of deities, “In some ways, the post-humans running a simulation are like gods. However, all the demigods except those at the fundamental level of reality are subject to sanctions by the more powerful gods living at lower levels.”

If the parallel universes are all running on the same computer platform could we communicate with them? If so, I hope the Matrix’s manic Agent Smith doesn’t materialize one day.

To borrow from the title of Isaac Asimov’s novel I Robot, the human condition might be described as I Subroutine.

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Serious blow to dark matter theories? New study finds mysterious lack of dark matter in Sun's neighborhood ›

"The most accurate study so far of the motions of stars in the Milky Way has found no evidence for dark matter in a large volume around the Sun. According to widely accepted theories, the solar neighbourhood was expected to be filled with dark matter, a mysterious invisible substance that can only be detected indirectly by the gravitational force it exerts. But a new study by a team of astronomers in Chile has found that these theories just do not fit the observational facts. This may mean that attempts to directly detect dark matter particles on Earth are unlikely to be successful."

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World's most powerful laser to tear apart the vacuum of space ›

"Capable of producing a beam of light so intense that it would be equivalent to the power received by the Earth from the sun focused onto a speck smaller than a tip of a pin, scientists claim it could allow them boil the very fabric of space – the vacuum."

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Researchers create computer simulations of primordial black holes striking the Earth ›

Black holes have captured the imagination of scientists and amateur enthusiasts for years. The idea of some dark entity out there in the far reaches of space sucking up anything and everything that ventures near with such power and force that even light can’t escape it’s clutches, both enthralls and terrifies. Thus, the idea of one moving close enough to our planet would seem good reason to hit the panic button. But, in some cases, it appears, it might not be such a bad thing, at least if it were very, very small. That’s what one small group of researchers has concluded after simulating the effects of one tiny black hole hitting and passing through the Earth, on a computer. 

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Laws of physics may change across the universe ›

New evidence supports the idea that we live in an area of the universe that is “just right” for our existence. The controversial finding comes from an observation that one of the constants of nature appears to be different in different parts of the cosmos.

If correct, this result stands against Einstein’s equivalence principle, which states that the laws of physics are the same everywhere. “This finding was a real surprise to everyone,” says John Webb of the University of New South Wales in Sydney, Australia. Webb is lead author on the new paper, which has been submitted to Physical Review Letters.

Even more surprising is the fact that the change in the constant appears to have an orientation, creating a “preferred direction”, or axis, across the cosmos. That idea was dismissed more than 100 years ago with the creation of Einstein’s special theory of relativity.

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Is Dark Energy Really "Repulsive Gravity"? ›

A powerful repulsion between normal matter and hidden pockets of antimatter could be an alternate explanation for the mysterious force known as dark energy, according to a controversial new theory.

In 1998 scientists discovered that the universe is not only expanding but that its expansion is accelerating.

This totally unexpected behavior has been called the “most profound problem” in physics, because our current understanding of gravity says that attractions between mass in the universe should be causing the expansion to slow down.

The leading theory to explain the accelerating expansion is the existence of a hypothetical repulsive force called dark energy. (Related: “New Galaxy Maps to Help Find Dark Energy Proof?”)

But in the new study, Massimo Villata, an astrophysicist at the Observatory of Turin in Italy, suggests the effects attributed to dark energy are actually due to a kind of “antigravity” created when normal matter and antimatter repel one another.

“Usually this repulsion is ascribed to a mysterious dark energy that would uniformly permeate the cosmos, but nobody knows what it is nor why it behaves this way,” Villata said in an email.

“We are replacing an unknown force caused by an unknown element with the repulsive gravity of the well-known antimatter.”

(Related: “Dark Matter Is an Illusion, New Antigravity Theory Says.”)

Scientists did not break speed of light - it was a faulty wire - Telegraph ›

"Einstein’s theory of special relativity, proposed in 1905, states that nothing in the universe can travel faster than the speed of light in a vacuum.

But researchers at the CERN lab near Geneva claimed they had recorded neutrinos, a type of tiny particle, travelling faster than the barrier of 186,282 miles (299,792 kilometers) per second.

Now it seems Einstein’s reputation has been restored after a source close to the experiment told the US journal Science Insider that “A bad connection between a GPS unit and a computer may be to blame.”

Crab Nebula's Pulsar May Be Fast Particle Accelerator ›

"The Crab Nebula (also designated M1 or NGC 1952) is visible through small telescopes, which has allowed astronomers to observe its growth and evolution since the supernovae that created it became visible in 1054 CE. A pulsar was found in the center of the Crab in 1968. This rapidly rotating neutron star is the core of the star that went supernova to make the nebula. In the intervening decades, x-ray, gamma ray, and radio observations have mapped the region of the nebula closest to the pulsar. During that mapping, it became apparent that the Crab pulsar is one of the brightest sources of gamma rays observable from Earth.

Despite all of those observations, we still don’t fully understand the Crab’s precise gamma ray spectrum, particularly recently observed pulses of intense gamma radiation seen by the Fermi Gamma-ray Space Telescope. Existing models certainly do well at describing much of the complex interplay between the intense magnetic fields of the pulsar and the winds of charged particles flowing outward. But no single scheme seems sufficient to cover all the observed phenomena.

A potentially promising new model, proposed by F. A. Aharonian, S. V. Bogovalov, and D. Khangulyan, may fill in some of these blanks. It proposes that areas near the pulsar are acting as rapid particle accelerators, but don’t boost electrons and heavier particles to the same extent.”

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CLOUD Experiment Chamber

The CLOUD (Cosmics Leaving OUtdoor Droplets) project aims to study the influence of galactic cosmic rays on the Earth’s climate through the media of aerosols and clouds.

Rare Element, Tellurium, Detected for the First Time in Ancient Stars

"The researchers found traces of this brittle, semiconducting element — which is very rare on Earth — in stars that are nearly 12 billion years old. The finding supports the theory that tellurium, along with even heavier elements in the periodic table, likely originated from a very rare type of supernova during a rapid process of nuclear fusion. The researchers published their findings online in Astrophysical Journal Letters.”

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ikenbot:

Odd Black Hole Is Last Survivor of Its Galaxy

The Hubble space telescope has spotted a supermassive black hole floating on the outskirts of a large galaxy.

The location is odd because black holes of this size generally form in the centers of galaxies, not at their edges. This suggests the black hole is the lone survivor of a now-disintegrated dwarf galaxy.

The black hole — named HLX-1 — is 20,000 times more massive than the sun, and is situated 290 million light-years away at the edge of the spiral galaxy ESO 243-49.

Hubble detected a great deal of energetic blue light coming from the black hole’s accretion disk — a massive collection of gas and dust that spirals into the black hole’s maw, generating x-rays. But scientists studying Hubble’s data also noticed the presence of cooler, red light, which shouldn’t have been there.

Astronomers suspect the red light indicates the existence of a cluster of young stars, roughly 200 million years old, orbiting around the black hole. These stars, in turn, are the key to explaining the chaotic history of the supermassive black hole.

HLX-1 was likely formed at the center of a dwarf galaxy that once orbited ESO 243-49. But in this dog-eat-dog universe of ours, large galaxies often swallow up their smaller brethren. When the dwarf galaxy came too close to ESO 243-49, the larger galaxy plucked away most of its stars, leaving behind the exposed central black hole.

The force of the galaxies’ collision would have also triggered the formation of new stars, explaining the presence of a young stellar cluster around the black hole. The cluster’s age, 200 million years, gives a good estimate of when the merger occurred.

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Journal Reference: Astrophysical Journal

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