Tag Archives: astrophysics

Ranking the most powerful forces in the Universe

Reposted from http://www.stumbleupon.com/su/1YetgF/:LYdzCxjD:TeSAV+gi/www.sentientdevelopments.com/2009/06/ranking-most-powerful-forces-in.html/

June 24, 2009

Ranking the most powerful forces in the Universe

There are a large number of forces at work in the Universe, some more powerful than others — and I’m not talking about the four fundamental forces of nature. A force in the context I’m talking about is any phenomenon in Universe that exhibits a powerful effect or influence on its environment. Many of these phenomenon quite obviously depend on the four basic forces to function (gravity, electromagnetism, the weak interaction and the strong interaction), but it’s the collective and emergent effects of these fundamental forces that I’m interested in.
And when I say power I don’t just mean the capacity to destroy or wreak havoc, though that’s an important criteria. A force should also be considered powerful if it can profoundly reorganize or manipulate its environment in a coherent or constructive way.
Albert Einstein once quipped that the most powerful force in the Universe was compound interest. While he does have a point, and with all due respect to the Master, I present to you my list of the four most powerful phenomenon currently making an impact in the Universe:
4. Supermassive Black Holes
There’s no question that black holes are scary; it’s the only part of the Universe that can truly destroy itself.
Indeed, Einstein himself, whose Theory of Relativity opened the door to the modern study of black holes, noted that “they are where God has divided by zero.” And it’s been said that the gravitational singularity, where the laws of physics collapse,  is the most complex mystery of science that still defies human knowledge.
Somewhat counterintuitively, black holes take the weakest of the four basic forces, gravity, to create a region of space with a gravitational field so powerful that nothing, not even light, can escape its pull. They’re called “black” because they absorb all the light that hits them and reflect nothing. They have a one-way surface, the event horizon, into which objects can fall, but out of which nothing (save for Hawking Radiation) can escape.
Black holes can also vary in size and gravitational intensity. Supermassive black holes are a million to a billion times the mass of a typical black hole. Most galaxies, if not all, are believed to contain supermassive black holes at their centers (including the Milky Way).
And recent studies are now suggesting that they are much larger than previously thought. Computer models reveal that the supermassive black hole at the heart of the giant galaxy M87 weighs the same as 6.4 billion suns—two to three times heavier than previous estimates.
That’s a lot of pull.
Indeed, should anything have the misfortune of getting close enough to a supermassive black hole, whether it be gas, stars or entire solar systems, it would be sucked into oblivion. Its gravitational pull would be so overwhelming that it would hurl gas and stars around it at almost the speed of light; the violent clashing would heat the gas up to over a million degrees.
Some have suggested that the supermassive black hole is the most powerful force in the Universe. While its ability to destroy the very fabric of space and time itself is undeniably impressive (to say the least), its localized and limited nature prevent it from being ranked any higher than fourth on my list. A black hole would never subsume an entire Galaxy, for example, at least not within cosmologically long time frames.
3. Gamma-Ray Bursts
The power of gamma-ray bursts (GRB) defies human comprehension.
Imagine a hypergiant star at the end of its life, a massive object that’s 150 times larger than our own. Extremely high levels of gamma radiation from its core is causing its energy to transform to matter. The resultant drop in energy causes the star to collapse. This results in a dramatic increase in the thermonuclear reactions that was burning within it. All this added energy overpowers the gravitational attraction and it explodes in a fury of energy — the hypergiant has gone hypernova.
This is not the stuff of fiction or theory — explosions like this have been observed. Hypernovas of this size can instantly expel about 10X46 joules. This is more energy than our sun produces over a period of 10 billion years. 10 billion years! In one cataclysmic explosion!
Hypernovas can wreak tremendous havoc in its local area, effectively sterilizing the region. These explosions produce highly collimated beams of hard gamma-rays that extend outward from the exploding star. Any unfortunate life-bearing planet that should come into contact with those beams would suffer a mass extinction (if not total extinction depending on its proximity to the supernova). Gamma-rays would eat up the ozone layer and indirectly cause the onset of an ice age due to the prevalence of NO2 molecules.
Supernovas can shoot out directed beams of gamma-rays to a distance of 100 light years, while hypernovas disburse gamma ray bursts as far as 500 to 1,000 light years away.
We are currently able to detect an average of about one gamma-ray burst per day. Because gamma-ray bursts are visible to distances encompassing most of the observable Universe — a volume encompassing many billions of galaxies — this suggests that gamma-ray bursts are exceedingly rare events per galaxy. Determining an exact rate is difficult, but for a galaxy of approximately the same size as the Milky Way, the expected rate (for hypernova-type events) is about one burst every 100,000 to 1,000,000 years.
Thankfully, hypergiant Eta Carinae, which is on the verge of going nova, is well over 7,500 light years away from Earth. We’ll be safe when it goes off, but you’ll be able to read by its light at night-time.
But not so fast — our safety may not be guaranteed. Some scientists believe that gamma-ray busters may be responsible for sterilizing giagantic swaths of the galaxy — in some cases as much as a quarter of the galaxy. Such speculation has given rise to the theory that gamma-ray bursters are the reason for the Fermi Paradox; exploding stars are continually stunting the potential for life to advance, making it the 3rd most powerful force in the Universe.
2. Self-Replication
A funny thing started to happen about 8 billion years ago: pieces of the Universe started to make copies of itself. This in turn kindled another phenomena: natural selection.
While this might not seem so impressive or powerful in its own right, it’s the complexification and the emergent effects of this process that’s interesting; what began as fairly straight forward cellular replication, at least on Earth, eventually progressed into viruses, dinosaurs, and human beings.
Self-replicating RNA/DNA has completely reshaped the planet, its surface and atmosphere molded by the processes of life. And it’s a process that has proven to be remarkably resilient. The Earth has been witness to some extremely calamitous events over its history, namely the Big Five Mass Extinctions, but life has picked itself up, dusted off, and started anew.
Now, what makes self-replication all the more powerful is that it is not limited to biological substrate. Computer viruses and memes provide other examples of how self-replication can work. Replicators can also be categorized according to the kind material support they require in order to go about self-assembly. In addition to natural replicators, which have all or most of their design from nonhuman sources (i.e. natural selection), there’s also the potential for:

  • Autotrophic replicators: Devices that could reproduce themselves in the wild and mine their own materials. It’s thought that non-biological autotrophic replicators could be designed by humans and could easily accept specifications for human products.
  • Self-reproductive systems: Systems that could produce copies of itself from industrial feedstocks such as metal bar and wire.
  • Self-assembling systems: Systems that could assemble copies of themselves from finished and delivered parts. Simple examples of such systems have been demonstrated at the macro scale.

It’s conjectured that a particularly potent form of self-replication will eventually come in the form of molecular manufacturing and the introduction of self-replicating nanobots. One version of this vision is connected with the idea of swarms of coordinated nanoscale robots working in tandem.
Microscopic self-replicating nanobots may not sound particularly powerful or scary, but what is scary is the prospect for unchecked exponential growth. A fear exists that nanomechanical robots could self-replicate using naturally occurring materials and consume the entire planet in their hunger for raw materials. Alternately they could simply crowd out natural life, outcompeting it for energy. This is what has been referred to as the grey goo or ecophagy scenario. Some estimates show, for example, that the Earth’s atmosphere could be destroyed by such devices in a little under two years.
Self-replication is also powerful in terms of what it could mean for interstellar exploration and colonization. By using exponentially self-replicating Von Neumann probes, for example, the Galaxy could be colonized in as little as one to ten million years.
And of course, if you can build you can destroy; the same technology could be used to sterilize the Galaxy in the same amount of time [for more on this topic read my article, “Seven ways to control the Galaxy with self-replicating probes“].
Consequently, self-replication sits at #2 on my list; its remarkable ability to reshape matter, adapt, grow, consume, build and destroy make it a formidable force to be reckoned with.
1. Intelligence
Without a doubt the most powerful force in the universe is intelligence.
The capacity to collect, share, reorganize and act on information is unlike anything else in this universe. Intelligent beings can build tools, adapt to and radically change their environment, create complex systems and act with reasoned intention. Intelligent beings can plan, solve problems, think abstractly, comprehend ideas, use language and learn.
In addition, intelligence can reflect on itself, predict outcomes and avoid peril; autonomous systems, for the most part, are incapable of such action.
Humanity, a particularly intelligent bunch owing to a few fortuitous evolutionary traits, has — for better or worse — become a force of nature on Earth. Our species has reworked the surface of the planet to meet its needs, significantly impacting on virtually every other species (bringing many to extinction) and irrevocably altering the condition of the atmosphere itself. Not content to stay at home, we have even sent our artifacts into space and visited our very own moon.
While some cynics may scoff at so-called human ‘intelligence’, there’s no denying that it has made a significant impact on the biosphere.
Moreover, what we think of as intelligence today may be a far cry from what’s possible. The advent of artificial superintelligence is poised to be a game-changer. A superintelligent agent, which may or may not have conscious or subjective experiences, is an intellect that is much smarter than the best human brains in practically every field, including problem solving, brute calculation, scientific creativity, general wisdom and social skills. Such entities may function as super-expert systems that work to execute on any goal it is given so long as it falls within the laws of physics and it has access to the requisite resources. That’s power. And that’s why it’s called the Technological Singularity; we have no idea how such an agent will behave once we get past the horizon.
Another more radical possibility (if that’s not radical enough) is that the future of the Universe itself will be influenced by intelligent life. The nature of intelligence and its presence in the Universe must always be called into question. There exists only one of two possibilities: intelligence is either 1) cosmological epiphenomenon, or 2) an intrinsic part of the Universe’s inner workings. If it’s the latter, perhaps we have some work to do in the future to ensure the Universe’s survival or to take part in its reproductive strategy.
Theories already exist in regards to stellar engineering — where a local sun could be tweaked in such a way to extend its lifespan. Future civilizations may eventually figure out how to re-engineer the Universe itself (such as re-working the constants) or create an escape hatch to basement universes. Thinkers who have explored these possibilities include Milan CirkovicJohn Smart, Ray Kurzweil, Alan Guth and James N. Gardner (for example, see Gardner’s book Biocosm: The New Scientific Theory of Evolution: Intelligent Life is the Architect of the Universe).
Intelligence as a force may not be particularly impressive today when considered alongside supermassive black holes, gamma-ray bursts and exponential self-replication. But it may be someday. The ability of intelligence to re-engineer its environment and work towards growth, refinement and self-preservation give it the potential to become the most powerful force in the Universe.

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Wormhole best time-travel option

Wormhole best time-travel option, astrophysicist says

By Jillian Scharr

Published August 27, 2013

LiveScience
  • Back to the Future

    In the movie “Back to the Future,” Doc Brown builds a time machine into a Delorean. (Universal)

The concept of a time machine typically conjures up images of an implausible plot device used in a few too many science-fiction storylines. But according to Albert Einstein’s general theory of relativity, which explains how gravity operates in the universe, real-life time travel isn’t just a vague fantasy.

Traveling forward in time is an uncontroversial possibility, according to Einstein’s theory. In fact, physicists have been able to send tiny particles called muons, which are similar to electrons, forward in time by manipulating the gravity around them. That’s not to say the technology for sending humans 100 years into the future will be available anytime soon, though.

Time travel to the past, however, is even less understood. Still, astrophysicist Eric W. Davis, of the EarthTech International Institute for Advanced Studies at Austin, argues that it’s possible. All you need, he says, is a wormhole, which is a theoretical passageway through space-time that is predicted by relativity. [Wacky Physics: The Coolest Little Particles in Nature]

“You can go into the future or into the past using traversable wormholes,” Davis told LiveScience.

Where’s my wormhole?
Wormholes have never been proven to exist, and if they are ever found, they are likely to be so tiny that a person couldn’t fit inside, never mind a spaceship.

‘There are numerous space-time geometry solutions that exhibit time travel.’

– Astrophysicist Eric W. Davis 

Even so, Davis’ paper, published in July in the American Institute of Aeronautics and Astronautics’ journal, addresses time machines and the possibility that a wormhole could become, or be used as, a means for traveling backward in time.

Both general-relativity theory and quantum theory appear to offer several possibilities for traveling along what physicists call a “closed, timelike curve,” or a path that cuts through time and space essentially, a time machine.

In fact, Davis said, scientists’ current understanding of the laws of physics “are infested with time machines whereby there are numerous space-time geometry solutions that exhibit time travel and/or have the properties of time machines.”

A wormhole would allow a ship, for instance, to travel from one point to another faster than the speed of light sort of. That’s because the ship would arrive at its destination sooner than a beam of light would, by taking a shortcut through space-time via the wormhole. That way, the vehicle doesn’t actually break the rule of the so-called universal speed limit the speed of light because the ship never actually travels at a speed faster than light. [Warped Physics: 10 Effects of Traveling Faster Than Light]

Theoretically, a wormhole could be used to cut not just through space, but through time as well.

“Time machines are unavoidable in our physical dimensional space-time,” David wrote in his paper. “Traversable wormholes imply time machines, and [the prediction of wormholes] spawned a number of follow-on research efforts on time machines.”

However, Davis added, turning a wormhole into a time machine won’t be easy. “It would take a Herculean effort to turn a wormhole into a time machine. It’s going to be tough enough to pull off a wormhole,” he told LiveScience.

That’s because once a wormhole is created, one or both ends of it would need to be accelerated through time to the desired position, according to general relativity theory.

Challenges ahead
There are several theories for how the laws of physics might work to prevent time travel through wormholes.

“Not only do we assume [time travel into the past] will not be possible in our lifetime, but we assume that the laws of physics, when fully understood, will rule it out entirely,” said Robert Owen, an astrophysicist at Oberlin College in Ohio who specializes in black holes and gravitation theory.

According to scientists’ current understanding, keeping a wormhole stable enough to traverse requires large amounts of exotic matter, a substance that is still very poorly understood.

General relativity can’t account for exotic matter according to general relativity, exotic matter can’t exist. But exotic matter does exist. That’s where quantum theory comes in. Like general relativity, quantum theory is a system for explaining the universe, kind of like a lens through which scientists observe the universe. [Video How to Time Travel]

However, exotic matter has only been observed in very small amounts not nearly enough to hold open a wormhole. Physicists would have to find a way to generate and harness large amounts of exotic matter if they hope to achieve this quasi-faster-than-light travel and, by extension, time travel.

Furthermore, other physicists have used quantum mechanics to posit that trying to travel through a wormhole would create something called a quantum back reaction.

In a quantum back reaction, the act of turning a wormhole into a time machine would cause a massive buildup of energy, ultimately destroying the wormhole just before it could be used as a time machine.

However, the mathematical model used to calculate quantum back reaction only takes into account one dimension of space-time.

“I am confident that, since [general relativity] theory has not failed yet, that its predictions for time machines, warp drives and wormholes remain valid and testable, regardless of what quantum theory has to say about those subjects,” Davis added.

This illustrates one of the key problems in theories of time travel: physicists have to ground their arguments in either general relativity or quantum theory, both of which are incomplete and unable to encompass the entirety of our complex, mysterious universe.

Before they can figure out time travel, physicists need to find a way to reconcile general relativity and quantum theory into a quantum theory of gravity. That theory will then serve as the basis for further study of time travel.

Therefore, Owen argues that it’s impossible to be certain of whether time travel is possible yet. “The wormhole-based time-machine idea takes into account general relativity, but it leaves out quantum mechanics,” Owen added. “But including quantum mechanics in the calculations seems to show us that the time machine couldn’t actually work the way we hope.”

Davis, however, believes scientists have discovered all they can about time machines from theory alone, and calls on physicists to focus first on faster-than-light travel.

“Until someone makes a wormhole or a warp drive, there’s no use getting hyped up about a time machine,” Davis told LiveScience.

Accomplishing this will require a universally accepted quantum gravity theory an immense challenge so don’t go booking those time-travel plans just yet.

Read more: http://www.foxnews.com/science/2013/08/27/wormhole-best-bet-for-time-machine/?intcmp=obinsite#ixzz2dIFw73ID

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Dark Matter Update

Dark matter, hidden substance that makes up the universe, possibly found by $2b space physics experiment

By Tia Ghose

Published April 03, 2013

Space.com

  • s134e007532

    The powerful Alpha Magnetic Spectrometer-2 (AMS) is visible at center left. The blackness of space and Earth’s horizon provide the backdrop for the scene, on May 20, 2011 (Flight Day 5 of the STS-134 shuttle mission). (NASA)

  • 478264main_ams_concept

    Artist’s concept of the Alpha Magnetic Spectrometer, a particle physics detector that will be installed on the starboard truss of the International Space Station. (NASA)

A massive particle detector mounted on the International Space Station may have detected elusive dark matter at last, scientists announced Wednesday.
The detector, the Alpha Magnetic Spectrometer (AMS), measures cosmic-ray particles in space. After detecting billions of these particles over a year and a half, the experiment recorded a signal that may be the result of dark matter, the hidden substance that makes up more than 80 percent of all matter in the universe.

AMS found about 400,000 positrons, the antimatter partner particles of electrons. The energies of these positrons suggest they might have been created when particles of dark matter collided and destroyed each other.

NASA will hold a press conference detailing the AMS science results at 1:30 p.m. EDT (1830 GMT) today. You can watch the AMS science results live on FoxNews.com.

Elusive matter
Dark matter emits no light and can’t be detected with telescopes, and it seems to dwarf the ordinary matter in the universe.

Physicists have suggested that dark matter is made of WIMPs, or weakly interacting massive particles, which almost never interact with normal matter particles. WIMPs are thought to be their own antimatter partner particles, so when two WIMPS meet, they would annihilate each other, as matter and antimatter partners destroy each other on contact. The result of such a violent collision between WIMPs would be a positron and an electron, said study co-author Roald Sagdeev, a physicist at the University of Maryland.

The characteristics of the positrons detected by AMS match predictions for the products of dark-matter collisions. For example, based on an overabundance of positrons measured by a satellite-based detector called the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA), scientists expected that positrons from dark matter would be found at energy levels higher than 10 gigaelectron volts (GeV), said study co-author Veronica Bindi, a physicist at the University of Hawaii.

And the positrons found by AMS increase in abundance from 10 GeV to 250 GeV, with the slope of the increase reducing by an order of magnitude over the range from 20 GeV to 250 GeV — just what scientists expect from positrons created by dark-matter annihilations.

Furthermore, the positrons appear to come from all directions in space, and not a single source in the sky. This finding is also what researchers expected from the products of dark matter, which is thought to permeate the universe.

Intriguing signal
The $2 billion AMS instrument was delivered to the International Space Station in May 2011 by the space shuttle Endeavour, and installed by spacewalking astronauts on the orbiting laboratory’s exterior backbone.

In just its first year and half, the AMS detector has measured 6.8 million positrons and electrons. As the instrument continues to collect data, scientists will be better able to tell whether the positron signal really does come from dark matter.

If the positrons aren’t created by annihilating WIMPs, there are other possible explanations. For example, spinning stars called pulsars spread out around the plane of our Milky Way galaxy.

But even with more AMS data, “we will still not be completely able to figure out if it’s really a dark-matter source or a pulsar,” Bindi told SPACE.com. To understand dark matter thoroughly, scientists hope to detect WIMPs directly via underground experiments on Earth, such as the Cryogenic Dark Matter Search and XENON Dark Matter projects.

Read more: http://www.foxnews.com/science/2013/04/03/dark-matter-major-astrophysics-discovery/?intcmp=features#ixzz2PQX63gak

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Dark Matter

This is republished from my Science Column in ConNotations Newszine, where I am a staff writer.  I also write book and movie reviews and other non-fiction for the magazine.  My science column is directed at convention fanboys and fangirls that were not self-punishing enough to get three science degrees like myself, but want to be able to understand complicated topics, like dark matter, string theory, teleportation, where the universe came from, astro-physics, the God Particle, and other issues.  My attempt with each short column is to explain a concept in layman’s terms.  This is on Dark Matter.  The photos were added for this web edition.

Is Space Empty or Full? 

by Michael Bradley

 Most have heard the term “dark matter” but what does it mean?  We look up at the night sky and we notice the stars, constellations, galaxies and heavenly bodies.  Unconsciously, we might also notice everything else – the black portion.  It is human nature to assume that the black portion represents nothingness, and emptiness broken up in its expanse only by those objects we can see.  For the known history of mankind, everyone would have accepted that as truth, until less than one hundred years ago.

As humans, we know and experience our reality through senses; smell, touch, sight, hearing, temperature, etc.  If we cannot sense something, it is often overlooked or missed by our minds.  In physics and astronomy the same is true.  We “see” the sky at night through two major lenses, one is the light emitted by heavenly bodies, and the second is the radiation and radio wave emissions from the sky.  We can observe the lights and the radiations and draw theories to understand them.

Based on the movement of the lights, we learned through observation that the planets rotate, that the Earth moves around the Sun, that we are in a galaxy called the Milky Way, that their are other galaxies, and many helpful facts.  The universe appears to be expanding, which also leads to the Big Bang Theory, calculations of time and so forth.

In the 1880s, Christian Doppler discovered the Doppler Effect, in which sound and light waves are compressed to different frequencies by the motion of mass.  For instance, a rushing locomotive sounds different as its mass moves toward and away from the listener.  This also creates the Blue/Red shift in light from celestial bodies.  As a galaxy spins, the section moving toward us turns bluer, while the section moving away turns redder on the light frequency spectrum.

Using the blue/red shift and physics, scientists were able to calculate the relative mass of galaxies and other objects which spin and cast off light.  Fritz Zwicky noticed in 1934 that the math did not add up, and came up with an explanation now known commonly as “dark matter.”  His theory is that either the majority of the mass of these objects does not give off light, or, the theory of gravitational pull is flawed in its calculations of mass.  To explain this missing mass, he theorized that there must be matter which neither reflects nor gives off light or radiation emissions measurable on Earth, but which has mass.  By only making calculations of spin based on visible matter, we are missing the dark matter.

If the dark matter theory is true, then 83% of the matter in the universe and 23% of the mass energy could be from dark matter.  It could be that our ability to perceive what space is composed of is much like a blind-folded man with ear muffs and a cold trying to describe his surroundings.  Or, consider a dark field and across from you are 1,000 people holding flashlights, but only 230 have them on.  So you think there are only 230 people.

Could there actually be so much out there that we can not see through light or through radiation?

Theorists have explored the possibilities for the last eighty years and have mainly created more theories than answers.  Some say the gravitational theory is wrong and that instead of trying to “fix” the math by the creation of a theoretical dark matter you should start there.  Some have broken up dark matter into deeper theoretical categories, such as Machos and Wimps.  You can’t make this stuff up.

Machos are Massive Astrophysical Compact Halo Objects more commonly referred to as brown dwarfs and black holes, or referred to as baryonic, or more normal matter, that happens to be dark.  Wimps are Weakly Interacting Massive Particles which would be non-baryonic in nature.  Wimps are thought to pass through normal matter though they have mass, without interacting with it.  There are also theories of the dark matter in which they break them into mixed dark matter, cold dark matter, warm dark matter and hot dark matter.  Who says physicists don’t have a sense of humor?

In any case, the next time you look up at the night sky, just realize that mathematically, either all we know about gravity is wrong, or you are seeing only a tiny portion of what is there.  It is 2012, and we often think we have it all figured out, and yet in the very night sky above our heads we understand and perceive very little.

 

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