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Threats From Space

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#1 bobdrake12

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Posted 23 November 2002 - 03:10 AM

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"Recently scientists have expressed concern that upper atmosphere explosions caused by small asteroids could be mistaken for nuclear detonations, especially during times of international tension. "


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Wednesday, 20 November, 2002, 22:02 GMT

Asteroid threat reassessed (excerpts)

By Dr David Whitehouse

BBC News Online science editor

Every year a small asteroid explodes in the Earth's atmosphere with an energy equivalent to 5,000 tonnes of TNT, according to new information.

The assessment comes from researchers who have studied about 300 impacts from space observed by US military surveillance satellites.

The scientists now estimate an object of the size that exploded over central Siberia in 1908 causing widespread devastation only strikes the Earth every 1,000 years or so. This is far less frequent than had been thought.

The asteroid impact assessment has been published in the journal Nature.

Military data

Asteroids with diameters smaller than 50-100 metres that collide with the Earth usually do not hit the ground as a single body. Rather, they detonate in the upper atmosphere.

A new analysis of the flashes of light from these exploding asteroids is possible because of data provided by the US Department of Defense from military satellites.

Positioned in geostationary orbit, the satellites have a view of a large part of the Earth and, because they are designed to detect light from rockets being launched, they are able to see the light flashes from space impacts as well.

Between February 1994 and September 2002, about 300 impact events were seen. From the intensity and duration of the light flashes, and some basic physics, it was possible to calculate the size of the incoming asteroids.

The researchers led by Dr Peter Brown, of the University of Western Ontario, Canada, estimate that every month an object explodes in the upper atmosphere with an energy equivalent to 300 tonnes of TNT.

'Harmful intruders'

Every 10 years, an object with the energy of 50 kilotonnes impacts the Earth.

An object like the one that struck Tunguska in central Siberia in 1908 hits us, on average, every 1,000 years or so. That object had an energy equivalent to 10 megatonnes of TNT. If such an object were ever to strike an inhabited area, millions of people could be killed.

Recently scientists have expressed concern that upper atmosphere explosions caused by small asteroids could be mistaken for nuclear detonations, especially during times of international tension.

Surveying the latest data, Dr Benny Peiser, of Liverpool John Moores University, UK, told BBC News Online: "This new research reinforces our view that we are constantly bombarded by cosmic debris large enough to be misinterpreted as a nuclear attack.

"The findings are a compelling warning that we need to start scanning the skies for small, but potentially harmful intruders

#2 Lazarus Long

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Posted 27 December 2002 - 02:37 PM

Here is an article from National Geographic's Top Ten Stories of the Year 2002. I am interested if everyone notices the significant amount of "Spin" that obviously went into this article. And of even greater importance, how little is mentioned of the more significant threat from 2002NT7, as the fly by is expected much sooner and there is still too little data to confirm the odds as precisely as the reader is made to believe. True the 1950DA has a probability of impact then 2002NT7 but it is 800 year as in the future.

What I find interesting is how the article refers to the same arguments that we have already presented here and in the earlier forum.

I think a great opportunity is being overlooked to turn a threat into an advantage.


Is a Large Asteroid Headed for Impact With Earth in 2880?

David Braun
National Geographic News
April 4, 2002

Scientists have identified a thousand-yard-wide (one-kilometer-wide) asteroid that may be heading for a collision with Earth—878 years from now.
Using radar and optical measurements made over the past 51 years, researchers have calculated that there is up to a one-in-300 possibility that Asteroid 1950 DA will slam into Earth on March 16, 2880. Their work is published in the April 5 issue of Science.

"We calculated the probability of collision based on what we know about the physical aspects of the asteroid and many other factors," said Jon Giorgini of NASA's Jet Propulsion Laboratory at the California Institute of Technology in Pasadena. "As we get more information we will be able to adjust the level of probability up or down."

Odds of one in 300 may seem almost insignificant, but it is the highest Earth-impact potential ever assigned by scientists to an object in space, according to Giorgini.

The consequences of a collision from an asteroid a thousand yards in diameter are speculative. Could a direct hit destroy an entire city? Would an ocean impact create a massive tsunami capable of deluging adjacent coast lines?

"Nothing good can come from such an impact," said Giorgini. "But a collision between 1950 DA and Earth is so unlikely it is not worth worrying about. And even if it does look like there could be a collision, we have plenty of time and many ways to deflect the asteroid from its path."

Posted ImageAsteroid 1950 DA, as seen by radar, has a one in 300 probability of colliding with Earth on March 16, 2880. The graphic shows the asteroid's position relative to Earth on April 5, 2002.

Image and art courtesy of NASA/JPL/Caltech

Changing the Trajectory

One of the easiest ways to deflect the asteroid past Earth would be to alter its surface, changing the amount of heat energy it radiates, said Joseph Spitale, a research associate in planetary science at the University of Arizona–Tucson. That would have the effect of subtly altering the way the asteroid moves, causing it to slowly change its trajectory.

In a separate paper published in Science, Spitale describes how the so-called Yarkovsky Effect could be used to make an asteroid drift off its path. The Yarkovsky Effect is a term used to describe how an asteroid's trajectory can be influenced by its heat radiation.

"The thermal emission from an asteroid acts like a rocket force in the opposite direction, although it is really, really weak," Spitale said. "If we can somehow change the thermal radiation being emitted by an asteroid, we can affect the object's orbit. A tiny thrust acting over a long time can be enough to nudge an asteroid from a path heading towards the Earth to one that narrowly misses the Earth."

Because the Yarkovsky Effect is completely determined by temperatures on the surface of a body, Spitale explained, it can be manipulated if the surface can be altered in a way that changes that temperature distribution.

Asteroid 1950 DA "looks like a good candidate to test the Yarkovsky Effect," he added. "We have a really long base line in time and we are able to predict its orbit over that time."

To use the Yarkovsky Effect to nudge 1950 DA off its course would require doing something on Earth to change the asteroid's surface temperatures.

"I think people will come up with all sorts of creative ideas about that," Spitale said. "For example, if we could cover the surface of the asteroid with one centimeter (half an inch) of dirt, that would plausibly be enough to change the Yarkovsky Effect quite a bit. Of course, that's a lot of dirt and it would probably require a couple of hundred rockets to get it all up there. It would be really expensive."

Another possible solution, Spitale said, would be to "paint" the asteroid's surface white. "That would make a big change to the way the object reflects sunlight. That might require a thickness of only one millimeter or so (less than a 20th of an inch) over the entire surface," he said.

A third solution might be the use of conventional explosives. One rocket might be enough to complete the job, and getting it there would certainly be possible using current space technology.

The last approach would be the cheapest solution, Spitale said. "Unfortunately, you would probably lose most of the debris to space," he said. "However, this approach might alter the character of the surface in some other useful way."

How to push 1950 DA away from the Earth—and whether it will ever be necessary to do so— depends entirely on the exact physical nature of the asteroid, said Giorgini. "We won't know for sure whether this asteroid is on a collision course until we can determine which way its north pole is pointing."

Current calculations are based on all the possibilities, and the outcome of these scenarios, he noted, ranges from a zero to 0.33 percent probability that there will be a convergence in the orbits of Earth and the asteroid.

Host of Factors

This is the first time such a wide array of factors has been taken into account in predicting an asteroid's orbit, Giorgini said.

He and the other researchers looked at not only the asteroid but also factors such as the gravitational influence of other asteroids, the shape of the sun, and the effect of solar wind (the forces created by light and heat from the sun).

Until now, 1950 DA had been seen only twice—once in 1950 and again on December 31, 2000. Although the asteroid orbits the sun once every 2.2 years, its orbit is close to that of Earth only about once in every 51 years.

The asteroid can be seen visually through telescopes as a moving point of light. Only through radar, however, can scientists determine the nature of its surface and how it spins.

Because the asteroid needs to be fairly close to Earth for radar to be effective, opportunities to study it with this technology are rare. Astronomers can use telescopes to observe the asteroid at greater distances before it fades from view.

The next time scientists will be able to use radar to study the asteroid will be in 2032. But Giorgini said astronomers will get an optical view of the asteroid in about five or six years, when there may be an opportunity to learn more about its physical aspects.

"We need to know how it spins, its mass, its exact shape, and the patterns of darkness and lightness on its surface," Giorgini said. "If we can't get this information from our telescopes, then the only way to do it will be to send a spacecraft to go and take a look at it."

#3 Lazarus Long

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Posted 15 August 2003 - 10:03 PM

Here is an article that I will include in this thread as I move it to the new forum where it belongs. It is not a specific "existential threat" yet may turn out to bear a causal relationship to many ones that we have previously outlined from cosmic collisions to ice ages. Heads up my fellow travelers the sky is not falling but but the forecast is for storms.

Defenses Down, Galactic Dust Storm Hits Solar System
Thu Aug 14,10:36 AM ET Science - Space.com!
By Robert Roy Britt
Senior Science Writer, SPACE.com

Our solar system's natural defenses are down and a vigorous cosmic dust storm is blowing through, according to a new study. The forecast calls for a prolonged and increasing blizzard of small interstellar bits.

While no serious consequences are expected, the extra dust could slightly alter our night sky and might pose an increased risk to spacecraft, which are vulnerable to high-speed impacts from the tiny small particles.

The whole scenario is also a vivid reminder that there is no such thing as empty space.

The number of incoming particles recently tripled and the pace is expected to grow over the next decade. Terrestrial weather and climate will not likely be affected, but more shooting stars could grace the night sky, said the study's leader, Markus Landgraf of the European Space Agency (ESA).

The fresh influx is related to a periodic weakening of the Sun's magnetic field.

The discovery was made using data from ESA's Ulysses spacecraft, which orbits the Sun on a noncircular path between Earth and Jupiter and his been monitoring the situation since 1992. The probe detects small particles and, based on direction, mass and speed, figures out which ones came from outside the solar system.

Threefold increase

The number of interstellar dust grains increased from four per day, per meter in 1997 to 12 per day in 2000, Landgraf said. The results were announced earlier this month. He expects the rate to stay constant until 2005, and then increase by another factor of 3 prior to 2013.

The potential effects are not well known, according to Landgraf and his colleagues at the Max-Planck-Institute.

"Generally interstellar dust is not considered a problem, as it does not penetrate typical spacecraft structures," Landgraf explained in an e-mail interview. "However, due to the high impact velocity, sensitive high-voltage instruments can suffer a short circuit after an exceptionally big impact. Also, sensitive optical instruments have to worry about the erosion of polished surfaces."

Most interstellar grains are just one-hundredth the diameter of a human hair. But they move fast, roughly 58,160 mph (26 kilometers per second) relative to the Sun.

Secondary effects

Any notable effects on Earth will likely involve secondary processes. When interstellar dust hits comets and asteroids, it's like shooting a tiny bullet at a rock, and more dust is kicked up, and the follow-on dust tends to be bigger.

More interstellar dust means more dust generated in-house.

"This has a number of potential effects," Landgraf said, cautioning that they haven't been observed yet, however.

One possibility is an increased number of sporadic meteors, those not associated with known showers like the summer Perseids or the November Leonids. Meteors are created when something vaporizes in Earth's atmosphere. Space rocks as big as peas and baseballs crash through now and then, but most shooting stars are made of mere dust.

It's also possible, Landgraf said, that the eerie Zodiacal Light -- a "false dawn" caused by sunlight reflecting off space dust -- will be enhanced.

And in general, more material might rain down to Earth from space every year.

Astronomers armed with huge telescopes will be interested to see if increased secondary dust brightens the Kuiper Belt, a region of frozen rocks and dust beyond Neptune. "With the brighter dust, especially infrared space telescopes will have a harder time to see faint objects behind the dust," Landgraf said.

Among other tasks, infrared telescopes on the ground and in space are used to study dust around other stars.

More to come

The solar system is always plowing through interstellar material. The Sun's giant magnetic field thwarts much of the dust from entering the solar system. But the magnetic field weakens periodically, on a cycle that lasts roughly 22-years. The cycle is related to an 11-year cycle of sunspot activity.

This is the first of the related dust storms that has been seriously monitored by a spacecraft.

Some day, the influx could get worse. The solar system is plowing toward the fringes of a galactic cloud known as the G-cloud.

"The time of the entry into the G-cloud is unknown, but is expected to occur any time in the next 10,000 years," Landgraf said. "There will be a constant increase [in dust rates], because the G-cloud is more dense than the local interstellar cloud that is now surrounding our Sun."

The study will be published in the Journal of Geophysical Research.

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#4 Lazarus Long

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Posted 02 September 2003 - 07:01 PM

You just got to love the irony of what is written and how we digest it. Also the timeliness of this council but now that we know such risks appear to be rising for some reason beyond our immediate understanding, just what are we going to do about them?

BTW, I am not trying to sound like chicken little and anyway this doesn't sound like one that will cause total extinction, just a lot of urban renewal in the wrong and very unlucky neighborhood where impact only "might" occur. [:o]

Asteroid Heading for Earth, May Hit in 2014
1 hour, 34 minutes ago Science - Reuters

LONDON (Reuters) - A giant asteroid is heading for Earth and could hit in 2014, U.S. astronomers have warned British space monitors.

But for those fearing Armageddon, don't be alarmed -- the chances of a catastrophic collision are just one in 909,000.

Asteroid "2003 QQ47" will be closely monitored over the next two months. Its potential strike date is March 21, 2014, but astronomers say that any risk of impact is likely to decrease as further data is gathered.

On impact, it could have the effect of 20 million Hiroshima atomic bombs, a spokesman for the British government's Near Earth Object Information Center told BBC radio.

The Center issued the warning about the asteroid after the giant rock was first observed in New Mexico by the Lincoln Near Earth Asteroid Research Program. "The Near Earth Object will be observable from Earth for the next two months and astronomers will continue to track it over this period," said Dr. Alan Fitzsimmons, one of the expert team advising the Center.

Asteroids such as 2003 QQ47 are chunks of rock left over from the formation of the solar system 4.5 billion years ago. Most are kept at a safe distance from the Earth in the asteroid belt between Mars and Jupiter.

But the gravitational influence of giant planets such as Jupiter can nudge asteroids out of these safe orbits and send them plunging toward Earth

#5 outlawpoet

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Posted 03 September 2003 - 10:42 AM

A Coma for Halley's Comet.

Halley's comet is observed by a land based telescope array at a whopping distance of 28.06 AU. Halley's comet is well into the dead portion of it's lifecycle and has no tail at this point. This is a very encouraging result from the perspective of detecting NEOs and other risks.

The resolving capability involved is analogized as to noticing a 5cm lump of coal in twighlight conditions at the distance of earth's diameter on the polar axis. This is not an easily imaginably scenario for me, but it is impressive sounding nonetheless.

The use of a telescopic array in this instance reinforces my intuition that small cheap sensors exchanging will outstrip large expensive units as to resolution, efficiency and cost ratios. The next step is a space based large array, which will provide orientability and even better resolution.

#6 AgentNyder

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Posted 03 September 2003 - 10:54 AM


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Astronomer Dr Carl Sagan worked out from some rather dubious estimates that there ought to be around 10,000,000 advanced technological civilisations in our galaxy, the Milky Way [2]. From equally dubious assumptions we can also work out the likelihood of aliens invading, say, in the next century, in a worst-case scenario. If we assume:

That the Earth hasn't been invaded by an alien race yet.
That the Earth has been around for approximately 4.5 billion years (that figure may have to be updated as this article gets older).
That the probability of aliens invading Earth has remained constant throughout the Earth's history.
Then, as a worst case scenario, presume that aliens invade tomorrow (or some time in the next century, if they're held up by bad weather, traffic congestion, or the wrong type of interstellar hydrogen). From a total of 45 million and one centuries, we will then only have been invaded in one century. Thus the probability of being invaded in the next century is vanishingly small, at only one in 45 million [3].

The chance of an alien invasion commencing in the very minute that the year 2000 starts [4] is therefore even smaller, at about one in 2,368,000,000,000,000. [5]


#7 Lazarus Long

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Posted 03 September 2003 - 11:53 AM

The Daleks are coming the DALEKS are COMING!!! [!] [alien] [cry] [alien]

This is what I mean about lumping all these "threats" into the same category because there is a natural tendency to extrapolate from one degree of probability to another and this encourages fallacious comparisons.

BTW, the threat of a superior intelligence as an alien invasion may be very small (IMO too) but more and more studies are suggesting that bacteria carried in spore form on cosmic dust storms may not be so far fetched and in fact still have to be considered as one of the reasonable abiogenesis theories.

Though in my opinion this only begs the question because the bacteria still had to evolve somewhere else.

The point is that an unknown pathogen arriving on a cosmic dust storm is not nearly as far fetched as the more commonly understood Sci-Fi thriller theory.

#8 Bruce Klein

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Posted 13 September 2003 - 04:16 AM

The black hole survival guide

New Scientist vol 179 issue 2411 - 06 September 2003, page 26

Falling into a black hole need not spell certain doom. Marcus Chown looks forward to the ultimate thrill ride

COULD you fall into a black hole and avoid being crushed by its intense gravity? Because the laws of physics break down under these conditions, it has widely been considered impossible even to imagine what would happen deep inside these fearsome objects. But Igor Novikov thought it was worth trying anyway. And by probing exactly how the laws of physics break down, he has challenged the conventional view that a trip to a black hole spells certain death.

Of course, Novikov, who heads the Theoretical Astrophysics Center in Copenhagen, Denmark, is not planning to visit a black hole. But physicists still consider the problem worth thinking about; these calculations can give us insight into what happens where the fabric of space-time becomes so tremendously warped that it shatters into droplets or quanta. "Here the general theory of relativity, Einstein's theory of gravity, is no longer valid," says Eric Poisson of the University of Guelph in Ontario, Canada. "We are into the mysterious domain of quantum gravity where no theory yet exists to tell us what to expect." So looking at the internal structure of black holes might tell us how to formulate a more consistent theory of the universe.

Black holes - regions of space-time from which nothing can escape - are rooted in Einstein's general theory of relativity. Soon after Einstein published his theory describing gravity as warps in space-time, the German astronomer Karl Schwarzschild used the theory to show that if a large star were squeezed into a small enough point, it would create such a strong gravitational field that nothing, not even light, could escape once it had moved beyond a certain point: the "event horizon".

Inside the event horizon of a black hole, space-time is radically transformed. Einstein showed that matter or energy stretch space and time, rather like someone standing on a trampoline. Yet no matter how much the fabric of space-time warps, space and time always act together to preserve the speed of light (one of the effects of this is that clocks run slower in the gravitational field close to Earth than they do far out in space). The tremendous gravity inside a black hole distorts space-time so much, that the only way to safeguard the speed of light travelling in this region is for space and time to swap roles. This has an extraordinary consequence: instead of being a place, the centre of a black hole exists in the future and you can no more avoid it than you can avoid tomorrow. At the end of this journey is the singularity, a point of infinite density that is widely believed to destroy anyone or anything that hits it.

The devastation is caused by "tidal" forces: because gravity varies so quickly near a black hole, the pull on your head would be much greater than the pull on your feet. Theorists calculate that these tidal forces increase indefinitely very close to the singularity: matter gets torn apart, space-time would shred and you would be utterly destroyed.

But it turns out that the existence of this murderous singularity does not necessarily spell doom. Because stars and galaxies rotate, there is a good chance that any black hole we encounter would too. In the early 1960s, New Zealand mathematician Roy Kerr worked out that this rotation drags the space-time surrounding the black hole like a tornado, profoundly altering its internal structure. His work showed that a second horizon forms inside a rotating black hole. Novikov has now shown that this second horizon changes everything (www.arxiv.org/abs/gr-qc/0304052).

Shortly after a rotating black hole forms, this inner horizon is little more than a slight wrinkle in space-time whose exact position depends on the speed of rotation. For the fastest spinning black holes, it sits halfway between the event horizon and the singularity. But it does not stay that way for ever. The extreme gravitational field inside the black hole whips all the in-falling light and matter up to extremely high energy. The colossal energy of this junk changes the character of the inner event horizon, warping it so much that the slight wrinkle in space-time becomes a deep fold. To preserve the speed of light in this region, time speeds up - it passes so quickly that the inner horizon concentrates junk from all times, even from events that happen far into the universe's future.

The result of this is that the inner event horizon concentrates so much light and matter that it rapidly turns into another singularity, one that concentrates an infinite amount of energy into a finite volume. Astrophysicists call it a "mass-inflation" singularity.

And it is this mass-inflation singularity that gets you out of a black hole alive. As well as junk falling into the black hole, Novikov believes that the inner event horizon also dredges up stuff scattered from deep within the black hole. This interacts with the incoming flow of light and matter, and "gravitational feedback", where the ever-increasing amount of stuff present causes an ever-increasing gravitational pull, causes the radius of the inner horizon to shrink. Eventually the mass-inflation singularity swallows the more dangerous singularity, leaving a tamer, less dangerous kind of black hole.

Calculations show that the tidal forces around a mass-inflation singularity may not last long enough to deform an object. Because space-time is so warped around there, passing near the singularity is the fastest part of the journey. That gives anyone falling into a black hole a fighting chance. "Although you would feel an infinite tidal force as you approached, you would feel it for only a very short time," Novikov says. "Consequently, you could pass through without being crushed."

Of course, you will have to choose your black hole carefully: it has certainly got to be rotating, for a start. It has also got to be old, so that there has been enough time for the second singularity to form. The final condition is that your black hole is big - very big.

That's because of the tidal forces. Near the small black holes formed by collapsing dead stars, they are enough to rip a person limb from limb. But these forces depend on the mass of the black hole, shrinking by a factor of 4 each time the mass doubles. So to increase your chances of survival, it is far better to explore a rotating supermassive black hole weighing hundreds of millions of times as much as the sun. "The tidal effect near such a supermassive black hole is far weaker than near a stellar-mass black hole," Poisson says. "So you would hardly notice as you slip across the event horizon and into the interior."

Fortunately, such behemoths do exist. No one is quite sure how they formed but astrophysicists now suspect that supermassive black holes lurk at the heart of every galaxy, including the Milky Way. Our nearest black hole, Sagittarius A*, is rotating, supermassive and old: a perfect candidate for this thrill ride of a lifetime. So, what would the journey be like?

Although the space-time around you is grossly warped - another way of saying that gravity is immensely strong - you notice nothing untoward happening, just as you don't normally notice the effects of Earth's gravity. To your friends watching you at a safe distance, however, things seem very different. Everything you do is in slow motion as time appears to stretch out interminably. Not only that, but you gradually fade from view as the visible light reflecting off you decreases in energy and frequency. In effect, gravity stretches the light waves, stretching or "red shifting" their wavelengths towards the infrared part of the spectrum.

Fantastic voyage

Immediately ahead of you lies the event horizon, the point of no return for in-falling light and matter. Here time appears to slow to a standstill, so your friends see your gradually fading image frozen in space forever. The truth (for you, anyway) is that you have long gone over the event horizon and are falling towards the singularity, the point with infinite density.

Once you are inside, your passage to the mass-inflation singularity should take only a few hours. Of course, you could prolong your journey by taking a zigzag route in a rocket through space, but the singularity is unavoidable. "By steering, you could extend the journey perhaps by a factor of 10, but no more than that," Poisson says.

And what would you find when you got there? So far, no one knows for sure. Many physicists believe that when a star's core collapses to form a black hole, it does not shrink to nothing, but instead spawns a new region of space-time. Lee Smolin of the Perimeter Institute in Ontario, Canada, for instance, speculates that black holes can give birth to baby universes where the fundamental constants of physics are slightly different. Novikov thinks mass-inflation singularities may act as portals into these regions; if you fall into a black hole you might emerge in a different universe, he says.

Amos Ori of the Israel-Technion Institute of Technology in Haifa, Israel, is exploring an extraordinary scenario that emerges when he applies general relativity to a simplified black hole model. He considered a two-dimensional black hole containing a mass-inflation singularity. "After crossing the mass-inflation singularity, an observer falling into the black hole will return to the external universe," he predicts. The bad news is, they will return stretched by an enormous factor and billions of years after they fell in. "Probably no observer will survive this," he says.

Unsurprisingly, many physicists are sceptical that anyone might travel through a black hole unscathed. "We don't know for sure if it is possible to survive crushing," says Kip Thorne, a theorist at the California Institute of Technology in Pasadena. "We don't have enough understanding of the mass-inflation singularity."

And even if you do not get crushed, another danger awaits you. Today's universe is filled with completely harmless microwave radiation, the tepid afterglow of the big bang. When these microwaves are sucked into a black hole, they are accelerated to much higher energies and frequencies: these innocuous microwaves get transformed into penetrating gamma radiation. "It is not obvious whether it will be possible to shield someone against these gamma rays," Ori says, "though there may be a chance."

If journeying into a black hole sounds too perilous, Novikov has an ingenious way of looking inside one without venturing too close to the event horizon. His idea is to use tunnels in space-time called wormholes, with one end anchored outside the black hole and the other dangling inside. "Light from the interior could then come out, allowing us to peer inside," he speculates. The big difficulty would be distorting space-time enough to make a wormhole in the first place. And then there is the problem of keeping it open: wormholes tend to snap shut as soon as they are formed. There has been recent progress this problem, however (see "Peeping through a wormhole"). But since it is impossible to change the topology of space-time, we would have to find a wormhole - possibly one left over from the big bang - then inflate it. "That's a tall order," Poisson says.

So maybe the best way to learn about the interior of a black hole is to disregard danger and hurl yourself into one. Of course, whatever you learned, you would never be able to tell your friends about it - even if you survived, you would emerge in another universe or at another time. "But it would be a fascinating trip," Poisson says. Any volunteers?

Peeping through a wormhole

Earlier this year, New Zealand and Indian physicists made a dramatic discovery: wormholes may be easier to maintain than we thought.

Wormholes are perfectly legitimate solutions of Einstein's equations, and could help us look inside a black hole without fear of falling in. But there is a problem: wormholes snap shut in an instant unless held open by a supply of exotic matter. Unlike the familiar stuff found on Earth, which always feels the pull of gravity, this exotic matter can repel gravity, halting the wormhole's collapse. Although recent measurements of the big bang afterglow suggest that the universe is made up of a substance with repulsive gravity, no one knows whether it has the right properties, or even if it exists in the quantities needed to prise open a wormhole big enough to look through.

But according to Matt Visser of Victoria University in Wellington, New Zealand, things are not as bad as they initially seemed (Physical Review Letters, vol 90, p 201102). The empty space of the quantum vacuum, where fluctuations in energy allow short-lived particles to pop in and out of existence, shares some of the properties of exotic matter. So it may be possible to keep open the mouth of wormhole with much smaller amounts of exotic matter than previously thought. Our chances of a glance inside black holes just went up - very, very slightly.

Marcus Chown

#9 chubtoad

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Posted 13 September 2003 - 06:31 AM

Would learning even be possible inside the event horizon? Since the ions in our body can't move faster than c they would be limited to a 180degree range of motion wouldn't they? Also if tachyons are found to exist(particles that have always bean traveling faster than c so they never had to accelerate through c) could any information be obtained from them?

#10 Lazarus Long

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Posted 28 September 2003 - 05:28 PM

Todays press out of India and a review will show that these events are more common when viewed globally than most people suspect. An interesting recent article connects Constantine's mass conversion of his troops to Christianity to a meteor impact that may have been simultaneous to the battle being waged at the time.

The early morning event was far enough away that it provided a spectacular light show and reflected an image of a cross from the mushroom cloud that rose over the impact crater that was reflected across the dawn sky with added color from the dust strew high into the atmosphere. For Constantine it was his sign of imminent victory and it worked for his soldiers were impressed enough to go and win against a larger force, reinforcing the mythological explanation.

Anyway here is the article:

Meteorite wrecks houses in India
BBC News Sunday, 28 September, 2003

At least 20 people are reported to have been injured after a meteorite crashed to Earth in eastern India. Reports say hundreds of people in the state of Orissa panicked when the fireball streamed across the sky. Burning fragments were said to have been fallen over a wide area, destroying several houses.

An official in Orissa said the authorities were assessing the damage and trying to recover what was left of the meteor. Reports from Orissa said windows rattled as the meteor passed overhead.

"It was all there for just a few seconds but it was like daylight everywhere," one resident said.

#11 Bruce Klein

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Posted 28 September 2003 - 05:30 PM

Wow... thanks for the update Laz.

#12 Lazarus Long

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Posted 03 October 2003 - 12:07 PM

About the same time the one mentioned above hit India this one went by and it was unseen until it passed us at the closest margin of any object in years. It wouldn't have destroyed the Earth but the hole it would make in a big city anywhere on Earth could have ruined that days commute if it is a solid iron type rock.

This make three objects to go by us unannounced in less than three years, I suggest that the odds here demonstrate the highest degree of probability of perceived Celestial threats and should not be ignored.

Also is it just coincidence? I suggest not as many of these objects are found clustered in bands when viewed looking at the solar system as a whole. One hit, one passed by and we are in a time when we annually experience meteor showers and some of the objects in these belts may be larger than previously thought.

Also as has been separately posted we are also entering a region of "galactic" space that appears to be far "dustier" than normal and this has begun to effect many calculations and also can herald a larger quantity of unforeseen objects that are not in specific orbit around the Sun but in a larger orbital relationship to the galaxy and subject to being captured by our system. While the odds that such an object will effect us directly are very small it is still a consideration.

Asteroid in near miss
By Dr David Whitehouse
BBC News Online science editor

Last week a small asteroid became the closest natural celestial object to pass by the Earth.

Posted Image
It posed no danger but it was close

It was found by astronomers at the Lowell Observatory in Arizona, which conducts a sky survey for so-called Near Earth Objects.

The 4 - 8 metre rock passed just 88,000 kilometres from the Earth on 27 September. That is 0.23 of the distance from the Earth to the Moon.

Designated 2003 SQ222 it was detected 11 hours after its closest approach.

Observations made by professionals and amateurs have allowed its orbit to be determined. It circles the Sun every 1.85 years.

Experts say the object is far too small to have posed a danger to Earth, although it would have been a spectacular fireball had it entered and partially fragmented in our atmosphere.

The previous record for closest approach of an asteroid was 108,000 km in 1994 by an object named 1994 XM1 that was about the same size as 2003 SQ222.

#13 Lazarus Long

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Posted 24 October 2003 - 05:28 PM

Get your radiation shielding out and light up your fields. Even some electronics in your cars could get wacko with this one.


Earth put on solar storm alert
By Dr David Whitehouse
BBC News Online science editor

It comes from one of the largest groups of sunspots seen for years. Several times in recent days superhot gas has erupted above them.

The events, called Coronal Mass Ejections, have sent 10 billion tonnes of superhot gas speeding towards Earth.

As well as communication blackouts, aurorae - polar lights - may be seen from mid-latitudes as the gas arrives.

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Full Text

#14 chubtoad

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Posted 31 October 2003 - 01:08 AM

Source: NASA/Goddard Space Flight Center
Date: 2003-10-30

NASA-Funded Earth Alert System To Aid In Disasters

The Maryland Emergency Management Agency (MEMA) has recently deployed a new communications system, based on NASA technology, that is designed to aid emergency management professionals when natural or man-made disasters occur.

During the early hours of Hurricane Isabel, key Maryland Emergency Management officials had access to Earth Alert, a system that enabled MEMA to quickly view personnel deployment and status on a map, track personnel movement, send text alerts as well as send messages to and from devices in the field. They were also able to report damages and coordinate response teams operating in the field. All these capabilities enabled MEMA to more efficiently provide relief to those in need.

MEMA is the state agency within the State of Maryland charged with the responsibility of reducing loss of life and property and protecting Maryland's institutions from natural and man-made disasters. The agency accomplishes this by coordinating the use of state resources during emergencies and disasters.

During a one-year pilot program, MEMA officials are testing the Earth Alert Emergency Management System, which was developed by 3e Technologies International (3eTI), Rockville, Md., and funded by NASA Goddard Space Flight Center's Technology Commercialization Office. As described by 3eTI, the Earth Alert System is a multi-faceted solution for Emergency Management Agencies/Organizations and First Responder communities.

This new system is another success story in NASA's Technology Transfer Program, whose major goal is to transfer technology derived from its space activities to the public and private sectors for the benefit of humankind. The development of the Earth Alert System is based on NASA Goddard's communications and information systems technologies.
"We have worked closely with 3eTi to help develop and implement a system that will enhance capabilities within the emergency management community. This one-year testing phase will allow us to provide feedback to the developers, and truly test its functionality," stated Clint Pipkin from MEMA's Readiness Division/Recovery Branch at Camp Fretterd Military Reservation located in Reisterstown, Md. "The system is now being used to provide logistic support at designated relief locations for MEMA Disaster Recovery Center personnel in areas hit hard by Hurricane Isabel."

Because Earth Alert is a hosted Web-based solution, it can be implemented without buying expensive call center infrastructure, networked computer servers, or special hardware for field deployment. It uses commercially available GPS-enabled wireless phones, off-the-shelf PCs and standard web browsers. During this one-year implementation phase, MEMA will test the system with 10 hand-held units and will provide valuable feedback that will allow 3eTI to customize the software to meet the unique requirements of emergency management personnel in Maryland.

The Disaster Recovery Center personnel at relief centers such as Annapolis, and Baltimore, are using a total of 10 Earth Alert units on a day-to-day basis. MEMA is using the Earth Alert system to locate the nearest Emergency Operations Center (EOC) Watch personnel on a map and to obtain their current status. This helps MEMA speed up response times and manage assets. The MEMA EOC can send standard messages and alert messages to the units in the field, and can receive messages from the units with location data.

Because of this capability MEMA can keep a log of critical messages and display the messages on a map for better a better understanding of the situation. MEMA is exploring many of the capabilities for further use such as Damage Assessment and First Responder reporting. These capabilities would aide relief efforts because they enable faster reporting and the ability to speed up relief to hard hit areas. These capabilities will require a more wide spread deployment and cooperation with local agencies.

MEMA can track personnel status through continuous map positioning, and shadow the progress of critical events through real-time management of personnel. These capabilities enhance personnel management, enable faster incident response time, and can mitigate incidents before they arise. With Earth Alert System capabilities, MEMA is now able to send situation alerts and weather alerts directly to field personnel based on their location or profile allowing the closest and best-equipped individuals to be directly routed to critical situations faster.

A successful beta test of the Earth Alert System during the January 2003 inauguration parade of Governor Robert L. Ehrlich Jr. sparked MEMA's decision to implement the system from June 2003 to May 2004. MEMA provided their parade staff with GPS-enabled Nextel two-way radios that allowed them to keep the parade on schedule and to monitor the crowd for suspicious behavior.

NASA initially conceived, sponsored and co-developed the first prototype of the warning system to broadcast survival information to isolated populations and then extended the original system to include the U.S. weather and communications satellite systems. From its Office of Commercial Programs, NASA provided funds for the Earth Alert System through the Small Business Innovation Research Program.

The Small Business Innovation Research (SBIR) and the Small Business Technology Transfer (STTR) programs provide opportunities for small, high technology companies and research institutions to participate in Government sponsored research and development efforts in key technology areas. The primary benefit of an SBIR/STTR project for a small business is in obtaining seed money to explore a technical idea without any loss of control or loss of equity, including intellectual property rights.

#15 Lazarus Long

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Posted 21 November 2003 - 03:29 AM

Here are two articles on an additional culprit in the death by rock scenario, a more subtle aspect of this story is that also there may be a pattern of longer periodicity with respect to the five major extinction,one that places us near term.
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Controversial New Claim in Death-by-Asteroid Case
Thu Nov 20, 3:49 PM ET Science - Space.com
By Robert Roy Britt
Senior Science Writer, SPACE.com

A longstanding mystery over what caused five great mass extinctions, including one that destroyed the dinosaurs, has grown with the release of two studies today in the journal Science.

In one study, researchers make the bold claim that an asteroid is responsible for the death of most life on Earth in a catastrophic extinction 251 million years ago. Other scientists are not ready to accept the claim.

Many experts have become convinced over the past two decades that the dinosaurs were exterminated 65 million years ago by an asteroid impact. Some findings suggest other mass extinctions, such as the one 251 million years ago, might also have been caused by rocks from space.

But the evidence is scant. Volcanic activity remains a suspect in the extinction cases, and a growing scientific minority is skeptical of the whole death-by-space-rock scenario.

The new study uncovered 40 extraterrestrial mineral fragments in the Antarctic, indicating the asteroid impact 251 million years ago. The timing coincides with the well-documented Permian-Triassic mass extinction, the worst of five major events scientists have identified through fossil records. Some 90 percent of all species disappeared, by some accounts. Scientists generally agree that the newfound tiny grains, called chondritic meteorite fragments, are indeed from space. But agreement stops there.

Too good to be true?

Study leader Asish Basu, a geochemist at the University of Rochester, and his colleagues are puzzled by their own discovery but have arrived at a conclusion nonetheless.

"It appears to us that the two largest mass extinctions in Earth history [65 million and 251 million years ago] were both caused by catastrophic collisions with chondritic meteoroids," the researchers write.

The pristine state of the fragments, however, does not make sense to other researchers. They should have long ago become indistinguishable soil, conventional wisdom holds. The fragments were collected from a layer dated to the Permian-Triassic boundary in time. They were embedded in rock 4-8 inches (10-20 centimeters) beneath the surface.

In a related analysis in Science by the science writer Richard Kerr, other scientists say they are stunned that the fragments survived for a quarter-billion years.

"I get the gut feeling it's wrong," said geochemist Birger Schmitz of the University of Goteborg in Sweden.

"It's astonishing, it's incredible, it's unbelievable," said Jeffrey Grossman of the U.S. Geological Survey (news - web sites). All those adjectives apply, Grossman later told SPACE.com, if the findings prove to be accurate. "Like all experiments it's going to have to be replicated," he said. And that replication is relatively simple. Another group of researchers can go to the same site in Antarctica, bring back their own samples, and analyze them.

Basu stands by the results. He insists the fragments were properly analyzed and that contamination in the sample was ruled out.

"We discovered them," Basu said in a telephone interview today. "Therefore they are there. Time will tell why they are there."

Basu added that the purpose of his team's scientific paper was not to explain how the grains held up over time. "The grains are there. Nobody can challenge that," he said. "We have to figure out how they survived."

Basu's team is back in Antarctica looking for more of the fragments. He said further research could solve the mystery.

Another culprit

Meanwhile, other researchers have been working to understand what role volcanoes might play in mass extinctions.

Deadly climate-altering gases spewed by volcanic eruptions could be the main culprit behind mass death, some figure. Others suppose volcanoes play just a supporting role. There is also the question of whether asteroid impacts trigger the volcanic activity and so are the root of all this evil either way.

Another new study in the journal suggests volcanoes might not be as deadly as some believe. And, if correct, it rules out the possibility that the dino-killing asteroid triggered intense volcanic activity known to have occurred in the era.

Researchers agree that at some time near the dinosaur extinction event 65 million years ago, a vast outpouring of volcanic material created a feature in India called the Deccan Traps, a bed of lava that covers an area about the size of Oregon and Washington states combined. But the timing has not been pinned down.

The Deccan volcanism occurred about 500,000 years before the end of the dinosaurs, according to the new research, by Greg Ravizza of the University of Hawaii and Bernhard Peucker-Ehrenbrink from the Woods Hole Oceanographic Institution.

The volcanoes loaded the air with carbon dioxide, fueling global warming (news - web sites), these scientists presume. Death of some species would have weakened the biological chain supporting dinosaurs.

Volcanic activity might have made life difficult for dinosaurs it seems, but an asteroid impact remains the prime suspect in their demise.


Asteroid May Have Hit Earth 251 Million Years Ago
Collision Could Have Caused Extinction Greater Than Impact That Killed Dinosaurs

11-20-03 1425EST

WASHINGTON (Nov. 20) - A massive asteroid may have collided with the Earth 251 million years ago and killed 90 percent of all life, an extinction even more severe than the meteorite impact that snuffed out the dinosaurs 66 million years ago.

A new study, based on meteorite fragments found in Antarctica, suggests the Permian-Triassic event, the greatest extinction in the planet's history, may have been triggered by a mountain-sized space rock that smashed into a southern land mass.

"It appears to us that the two largest mass extinctions in Earth history ... were both caused by catastrophic collisions" with meteoroids, the researchers say in their study appearing this week in the journal Science.

Asish R. Basu, a professor of Earth sciences at the University of Rochester, said proof of a massive impact 251 million years ago is in the chemistry found in rocky fragments recovered on Graphite Peak in Antarctica. He said the fragments were found at a geological horizon, or layer, that was laid down at the start of the Permian-Triassic extinction. Analysis shows the fragments have chemical ratios that are unique to meteorites.

"The only place you would find the chemical composition that we found in these fragments is in very primitive, 4.6-billion-year-old meteorites, as old as our Earth," said Basu, the first author of the study.

Basu said the Permian-Triassic asteroid was probably bigger than the six-mile-wide space rock that is thought to have killed the dinosaurs. Such an impact could cause a huge fireball and send billions of tons of dust into the atmosphere, enough to darken the sun for months. It also would have laid down a layer of dust bearing the same chemical composition as the meteorite.

The dinosaur-killing asteroid left a thin layer of the element iridium across the globe. But Basu said iridium was not found in the fragments recovered from the Antarctica, suggesting the earlier Permian-Triassic asteroid had a different composition. Basu said specimens recovered from Permian-Triassic rock formations in China, however, have a chemistry that matches that of the meteorite fragments found in Antarctica, a discovery that supports the impact theory. Also, shocked quartz, a telltale sign of an asteroid impact, has been found at both sites, he said.

At the time of the Permian-Triassic event, Africa, South America, India, Australia and Antarctica were joined in a giant continent called Pangea. Just where the asteroid hit in that land mass is uncertain, Basu said, but it could have been near what is now western Australia. Life on Earth 251 million years ago was far different from what it is now or what it was when dinosaurs lived.

"There were no large animals then, but there were lots of species living on the land and in the sea, and there were plants," said Basu. The most dominant plant, which is found commonly in fossil beds from the Permian-Triassic, was a giant fern called glossopteris. In the geological layers following the impact, that fern is absent from the fossil record.

"That was the last blooming of that plant," said Basu. "After that, it was gone forever from the planet."

Massive outflows of lava, called flood basalt, occurred around the time of both the Permian-Triassic and the dinosaur extinctions. The outflow continued for thousands of years and thickly covered hundreds of miles. Basu said it is possible that asteroid impacts triggered both eruptions of lava, but the connection has yet to be proven.

Some experts are skeptical that Basu and his co-authors have found 251-million-year-old meteorite metals, although nobody questions that the material did come from outer space. The surprise is that the specimens survived the weathering on Earth for so long.

"Nobody has even seen anything like this before," said Jeffrey N. Grossman, a researcher with the United States Geologic Survey in Reston, Va. "It is incredibly fresh and that is astonishing."

David A. Kring, a planetary geologist at the University of Arizona, said it is clear that material found by Basu and his team is from an asteroid, "but it is unlike the debris we have seen in other impact ejecta."

As a result, said Kring, "there are enough questions ... that I don't think one can say that an impact is conclusively linked to the Permian-Triassic extinction. We need to go back and test the hypothesis."

#16 Lazarus Long

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Posted 21 November 2003 - 03:43 AM

Here are the Five Great Extinctions. It should be noted that in terms of the fossil record being created right now the impact of humanity on this planet is ranking up to being sixth on the list of all time worst disasters to impact life on Earth.

The question is whether we "credit" a value to life other than human. But the numbers speak for themselves and in terms of percentages we have caused the highest number of extinctions of species since the KT Event (Cretaceous-Tertiary) and our raw numbers weigh in at equivalent to the worst level of disaster whether by impact, volcanism, or glaciation.

I don't use the term the Human Glacier for nothing, or lightly.


The Five Worst Extinctions in Earth's History
By Lee Siegel
Science Writer
posted: 04:12 pm ET 07 September 2000

Here are details of the five worst mass extinctions in Earth’s history and their possible causes, according to paleobiologist Doug Erwin of the Smithsonian Institution’s National Museum of Natural History. Erwin said estimates of extinction rates are from the late John J. Sepkoski at the University of Chicago:

Cretaceous-Tertiary extinction, about 65 million years ago, probably caused or aggravated by impact of several-mile-wide asteroid that created the Chicxulub crater now hidden on the Yucatan Peninsula and beneath the Gulf of Mexico. Some argue for other causes, including gradual climate change or flood-like volcanic eruptions of basalt lava from India’s Deccan Traps. The extinction killed 16 percent of marine families, 47 percent of marine genera (the classification above species) and 18 percent of land vertebrate families, including the dinosaurs.

End Triassic extinction, roughly 199 million to 214 million years ago, most likely caused by massive floods of lava erupting from the central Atlantic magmatic province -- an event that triggered the opening of the Atlantic Ocean. The volcanism may have led to deadly global warming. Rocks from the eruptions now are found in the eastern United States, eastern Brazil, North Africa and Spain. The death toll: 22 percent of marine families, 52 percent of marine genera. Vertebrate deaths are unclear.

Permian-Triassic extinction, about 251 million years ago. Many scientists suspect a comet or asteroid impact, although direct evidence has not been found. Others believe the cause was flood volcanism from the Siberian Traps and related loss of oxygen in the seas. Still others believe the impact triggered the volcanism and also may have done so during the Cretaceous-Tertiary extinction. The Permian-Triassic catastrophe was Earth’s worst mass extinction, killing 95 percent of all species, 53 percent of marine families, 84 percent of marine genera and an estimated 70 percent of land species such as plants, insects and vertebrate animals.

Late Devonian extinction, about 364 million years ago, cause unknown. It killed 22 percent of marine families and 57 percent of marine genera. Erwin said little is known about land organisms at the time.

Ordovician-Silurian extinction, about 439 million years ago, caused by a drop in sea levels as glaciers formed, then by rising sea levels as glaciers melted. The toll: 25 percent of marine families and 60 percent of marine genera.

#17 Bruce Klein

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Posted 19 February 2004 - 07:39 AM

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From Space, a New View of Doomsday


Once upon a time, if you wanted to talk about the end of the universe you had a choice, as Robert Frost put it, between fire and ice.

Either the universe would collapse under its own weight one day, in a fiery "big crunch," or the galaxies, now flying outward from each other, would go on coasting outward forever, forever slowing, but never stopping while the cosmos grew darker and darker, colder and colder, as the stars gradually burned out like tired bulbs.

Now there is the Big Rip.

Recent astronomical measurements, scientists say, cannot rule out the possibility that in a few billion years a mysterious force permeating space-time will be strong enough to blow everything apart, shred rocks, animals, molecules and finally even atoms in a last seemingly mad instant of cosmic self-abnegation.

"In some ways it sounds more like science fiction than fact," said Dr. Robert Caldwell, a Dartmouth physicist who described this apocalyptic possibility in a paper with Dr. Marc Kamionkowski and Dr. Nevin Weinberg, from the California Institute of Technology, last year.

The Big Rip is only one of a constellation of doomsday possibilities resulting from the discovery by two teams of astronomers six years ago that a mysterious force called dark energy seems to be wrenching the universe apart.

Instead of slowing down from cosmic gravity, as cosmologists had presumed for a century, the galaxies started speeding up about five billion years ago, like a driver hitting the gas pedal after passing a tollbooth.

Dark energy sounded crazy at the time, but in the intervening years a cascade of observations have strengthened the case that something truly weird is going on in the sky. It has a name, but that belies the fact that nobody really knows what dark energy is.

In six years it has become one of the central and apparently unavoidable features of the cosmos, the surprise question mark at the top of everybody's list, undermining what physicists presumed they understood about space, time, gravity and the future of the universe.

"In five years we've gone from saying it looks like a mistake to something that everyone is claiming evidence for," said Dr. Robert Kirshner of the Harvard-Smithsonian Center for Astrophysics, who was part of the original discovery.

Dr. Saul Perlmutter, a physicist from the Lawrence Berkeley Laboratory who was a leader of one of the 1998 teams, said he thought astronomers had even gotten comfortable with the idea — "or as comfortable as you can be with something as bizarre as dark energy."

Now, armies of astronomers are fanning out into the night, enlisting telescopes, large and small, from Chile to Hawaii to Arizona to outer space, in a quest to take the measure of dark energy by tracing the history of the universe with unprecedented precision.

Some of them are following the trail blazed by the first two groups six years ago, searching out a kind of exploding star known as Type 1a the supernova. Those stars serve as markers in space, enabling scientists to plumb the size of the universe and how it grew over time. Where the first groups based their conclusions on observing a few dozen supernovas, the new efforts intend to harvest hundreds or thousands of them.

Others are seeking to gain leverage by investigating how the antigravitational force of dark energy has retarded the growth of conglomerations of matter like galaxies. In one ambitious project, a team led by Dr. John Carlstrom of the University of Chicago is building an array of radio telescopes at the South Pole to count and study clusters of galaxies deep in space-time. Others are already probing the internal dynamics of galaxies by the thousands, or building giant cameras that use the light-bending powers of gravity itself as lenses to map invisible dark matter in space and compile a growth chart of cosmic structures.

Dr. Anthony Tyson, now at Bell Laboratories, is head of a project to build a "dark matter telescope" known as the Large Synoptic Survey Telescope. "High energy physicists have been marching into our project," he said. "This is not just another telescope. It's a physics experiment, like a particle accelerator."

After all, the fate of the universe is at stake. If the dark energy is virulent enough, then that fate "is quite fantastic and completely different than the possibilities previously discussed," Dr. Caldwell and his colleagues wrote last year.

The Search for One Number

The idea of an antigravitational force pervading the cosmos does sound like science fiction, but theorists have long known that certain energy fields would exert negative pressure that would in turn, according to Einstein's equations, produce negative gravity. Indeed, some kind of brief and violent antigravitational boost, called inflation, is thought by theorists to have fueled the Big Bang.

As they try to figure out how this strange behavior could be happening to the universe today, astronomers say the ultimate prize from all the new observing projects could be as simple as a single number.

That number, known as w, is the ratio between the pressure and density of dark energy. Knowing this number and how it changes with time — if it does — might help scientists pick through different explanations of dark energy and thus the future of the universe — "whether it's gonna lead to a Big Rip, a Big Collapse or just a Big Fizzle," as Dr. Adam Riess of the Space Telescope Science Institute in Baltimore put it in an e-mail message.

One possible explanation for dark energy, perhaps the sentimental favorite among astronomers, is a force known as the cosmological constant, caused by the energy residing in empty space. It was first postulated back by Einstein in 1917. A universe under its influence would accelerate forever.

While the density of energy in space would remain the same over the eons, as the universe grows there would be more space and thus more repulsion. Within a few billion years, most galaxies would be moving away from our own faster than the speed of light and so would disappear from the sky; the edge of the observable universe would shrink around our descendants like a black hole.

But attempts to calculate the cosmological constant using the most high-powered modern theories of gravity and particle physics result in numbers 1060 times as great as the dark energy astronomers have observed — big enough, in fact, to have blown the universe apart in the first second, long before even atoms had time for form. Theorists admit they are at a loss. Perhaps, some of them now say, Einstein's theory of gravity, the general theory of relativity, needs to be modified.

Another possibility comes from string theory, the putative theory of everything, which allows that space could be laced with other energy fields, associated with particles or forces as yet undiscovered. Those fields, collectively called quintessence, could have an antigravity effect. Quintessence could change with time — for example, getting weaker and eventually disappearing as the universe expanded and diluted the field — or could even change from a repulsive force to an attractive one, which could set off a big crunch.

Recently, in a variation on the quintessence idea, Dr. Leonard Parker of the University of Wisconsin at Milwaukee and various colleagues, including Dr. Caldwell, have suggested that the field associated with some unknown very light particle could get tangled up with gravity and cause the universe to accelerate. That would alter Einstein's equations, said Dr. Caldwell. He added, "Our calculations show, however, that galaxies reside in a bubble of old-fashioned Einstein gravity, whereas gravity has changed outside and between galaxies."

A Weird Idea Gets Weirder

But the strangest notion is what Dr. Caldwell has called phantom energy, the dark energy that could lead to the Big Rip.

"It's weird negative pressure," said Dr. Lawrence M. Krauss, an astrophysicist at Case Western Reserve University in Cleveland.

While the density of the energy in Einstein's cosmological constant stays the same as the universe expands, the density of phantom energy would go up and up, eventually becoming infinite. Such would be the case if the parameter w turned out to be less than minus 1, say physicists, who admit they are stunned by the possibility and until recently simply refused to consider it.

"It crosses a boundary of good taste," Dr. Caldwell said, calling phantom energy "bad news stuff." Phantom energy violates physicists' intuitions about how the universe should behave. A chunk of it could be used to prop open wormholes in space and time — and thus create time machines, for example.

"It could lead to such bizarre effects as negative kinetic energy," Dr. Krauss said. As a result, objects like atoms would be able to lose energy by speeding up.

Nevertheless, a recent analysis by Dr. Caldwell and his Dartmouth colleague Dr. Michael Doran of the supernova measurements to date, combined with other cosmological data, suggest that w could lie anywhere from minus 0.8 to minus 1.25, leaving open the possibility of phantom energy. The cosmological constant would give a value of minus 1.0, and anything higher would be a sign of quintessence.

Dr. Kirshner said phantom energy had been dismissed as "too strange" when his group was doing calculations of dark energy back in 1998. In retrospect, he said, that was not the right thing to do.

"It sounds wacky," he said, referring to phantom energy, "but I think we're in a situation where we're going to need a really new idea. We're in trouble; the way out is going to be new imaginative things. It might be our ideas are not wild enough, they don't question fundamentals enough."

Dr. Chris Pritchet of the University of Victoria, who is part of a collaboration using the Canada-France-Hawaii telescope on Mauna Kea to search for supernovas, said, "In many ways phantom energy is unphysical, but we're not ruling it out."

Counting Down to the Big Rip

This version of doomsday would start slowly. Then, billions of years from now, as phantom energy increased its push and the cosmic expansion accelerated, more and more galaxies would start to disappear from the sky as their speeds reached the speed of light.

But things would not stop there. Some billions of years from now, depending on the exact value of w, the phantom force from the phantom energy will be enough to overcome gravity and break up clusters of galaxies. That will happen about a billion years before the Big Rip itself.

After that the apocalypse speeds up. About 900 million years later, about 60 million years before the end, our own Milky Way galaxy will be torn apart. Three months before the rip, the solar system will fly apart. The Earth will explode when there is half an hour left on the cosmic clock.

The last item on Dr. Caldwell's doomsday agenda is the dissolution of atoms, 10-19, a tenth of a billionth of a billionth of a second before the Big Rip ends everything.

"After the rip is like before the Big Bang," Dr. Caldwell said. "General relativity says: "The end. Time can't evolve."

The cosmos probably still has a lot of life in it, according to recent calculations by Dr. Krauss. Based on the current age of the universe, some 14 billion years, and other data, w cannot be less than about minus 1.2, he said, putting the Big Rip about 55 billion years in the future.

"It can't be very phantom," Dr. Krauss said.

The dark energy surveys now under way hope to be able to measure w to an accuracy of 5 percent, but even if that can be done, it may not be sufficient to eliminate the nightmare of phantom energy.

"It's hard to measure anything in astronomy to a few percent," said Dr. Sandra Faber of the University of California at Santa Cruz, who directs one of the dark energy surveys. Variations in the atmosphere and gaps in astronomers' understanding of supernova explosions add uncertainty to the dark energy measurements.

As a result some astronomers fear that the results may leave us on the razor's edge unable to decide between a cosmological constant and the other possibilities — quintessence or a Big Rip. Cosmologists could then be stuck with a "standard model" of the universe that fits all the data, but which they have no hope of understanding.

If the parameter w comes out to be something other than minus 1, Dr. Krauss said, it will at least give some direction to physicists.

One encouraging sign — "a tantalizing bit of hope," in Dr. Krauss's words — that the data will distinguish between a cosmological constant and the other possibilities came last fall when Dr. Riess, of Baltimore, reported, based on new observations of distant supernovas, that the "cosmic jerk" when dark energy took over the universe happened only five billion years ago.

In the standard cosmological constant model, said Dr. Riess, the turnaround should have come one or two billion years earlier.

Dr. Tyson was more sanguine. "Dark energy is crazy, right?" he said. "It's going to be exciting no matter what we find."

Dark Future for Dark Energy?

The work of the dark energy hunters has been complicated by the impending loss of the Hubble Space Telescope, which can see far enough out in space and time to measure how and if the dark energy parameter w is changing over the eons.

Last month, citing safety, NASA canceled all future shuttle maintenance missions to the telescope, dooming it to die in orbit, probably within three years, according to astronomers. "The Hubble shutdown will slow us all down," Dr. Perlmutter said.

At the same time, as a result of the agency's presidentially ordered shift toward the Moon and Mars, plans for a special satellite that was to have been jointly sponsored by NASA and the Department of Energy have at least temporarily disappeared from NASA's five-year budget plan.

Dr. Perlmutter, who has devoted much of his time in the last six years to the proposed satellite experiment, said he hoped that a way would be found to keep the project on track to be launched in the next decade.

"When you have the most exciting scientific problem of the day, you don't want to wait around," he said.

#18 PaulH

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Posted 19 February 2004 - 09:42 AM

I hope to be around to find out if I am right or wrong, but I think intelligence will survive this "Big Rip". Ok, so we have only a few billion years to figure it out. Look how much we've already figured out in a few hundred years using our tiny, slow, three pound pieces of sloppy wetware. Now if an asteroid comes to the earth, it won't stand a chance. Given the speed-up of accelerating intelligence on super-fast substrates combined with a radical increase in overall intelligence, and a much larger quantity of intelligence-computronium. In a few billion years when this "Big Rip" becomes evident I have little doubt that this googleplex intelligence will have solved the problem and implemented the solution.

I agree with Kurzweil, the limits of physical law for all practical purposes essentially evaporates in the presence of sufficient intelligence.

Edited by planetp, 19 February 2004 - 10:21 AM.

#19 Bruce Klein

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Posted 19 February 2004 - 10:18 AM

Quite refreshing... thanks of for sharing your view. I tend to agree.

#20 PaulH

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Posted 22 February 2004 - 09:18 PM

As is typical of cosmology these days, it looks like the Big Rip idea is being questioned. It appears from the latest observations that dark energy may be a constant, and even weakening as the universe expands, meaning that gravity will re-exert it's influence and bring the universe back together, culminating in a Big Crunch. If that is the case the Frank Tipler's Omega Point theory gains credence agan.

#21 advancedatheist

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Posted 25 February 2004 - 03:51 PM


Earth almost put on impact alert

By Dr David Whitehouse
BBC News Online science editor 

No one was quite sure at the beginning where 2004 AS1 was headed 

Astronomers have revealed how they came within minutes of alerting the world to a potential asteroid strike last month.
Some scientists believed on 13 January that a 30m object, later designated 2004 AS1, had a one-in-four chance of hitting the planet within 36 hours.

It could have caused local devastation and the researchers contemplated a call to President Bush before new data finally showed there was no danger.

The procedures for raising the alarm in such circumstances are now being revised.

At the time, the president's team would have been putting the final touches to a speech he was due to make the following day at the headquarters of Nasa, the US space agency.

In it he planned to reset the course of manned spaceflight, sending it back to the Moon and on to Mars, but he could have had something very different to say.

He could have begun by warning the world it was about to be hit by a space rock.

Bush would not have known where it would impact - only somewhere in the Northern Hemisphere. Experts would have been bouncing radar signals off the huge rock as he spoke in order to get more information about its trajectory.

At about 30m wide, the asteroid was cosmic small fry, not the type of thing to wipe out the dinosaurs or threaten our species, but still big enough to cause considerable damage after exploding in the atmosphere....

Many astronomers recognise that they a false alarm [sic] could have brought ridicule on their profession. They are calling for more planning and less panic if it should happen for real next time.

And 2004 AS1? It turned out to be bigger than anyone had thought - about 500m wide. It eventually passed the Earth at a distance of about 12 million km - 32 times the Earth-Moon distance, posing no danger to us whatsoever.

#22 Bruce Klein

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Posted 25 February 2004 - 06:45 PM

Thanks Mark.

I suspect we will eventually find a way to map all NEA's. But, I don't quite feel safe yet.

#23 tony335

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Posted 13 March 2004 - 09:09 PM

Setting up some type of early warning system would be a start, but we'd also need some means of preventing an impact with Earth, if the object happened to be on colision trajectory with our planet. I doubt whether we're in the state to put together a mission that could react in time. One way would be to mount chemical/ion thrusters or a solar sail or an m2p2 drive to the object, either slowing or increasing its speed. But I doubt that is currently feasible. I think we need a program to study the possibilities and we need it soon.

#24 advancedatheist

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Posted 18 March 2004 - 06:39 AM

Posted Image


Steven R. Chesley
Paul W. Chodas
NASA's Near Earth Object Program Office
Wednesday, March 17, 2004
A small near-Earth asteroid (NEA), discovered Monday night by the NASA-funded LINEAR asteroid survey, will make the closest approach to Earth ever recorded. There is no danger of a collision with the Earth during this encounter.

The object, designated 2004 FH, is roughly 30 meters (100 feet) in diameter and will pass just 43,000 km (26,500 miles, or about 3.4 Earth diameters) above the Earth's surface on March 18th at 5:08 PM EST (2:08 PM PST, 22:08 UTC). (Close approach details here).

On average, objects about the size of 2004 FH pass within this distance roughly once every two years, but most of these small objects pass by undetected. This particular close approach is unusual only in the sense that scientists know about it. The fact that an object as small as asteroid 2004 FH has been discovered now is mostly a matter of perseverance by the LINEAR team, who are funded by NASA to search for larger kilometer-sized NEAs, but also routinely detect much smaller objects.

Asteroid 2004 FH's point of closest approach with the Earth will be over the South Atlantic Ocean. Using a good pair of binoculars, the object will be bright enough to be seen during this close approach from areas of Europe, Asia and most of the Southern Hemisphere.

Scientists look forward to the flyby as it will provide them an unprecedented opportunity to study a small NEA asteroid up close.

Posted Image

#25 Lazarus Long

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Posted 28 March 2005 - 05:32 PM

Here is another variant on the K/T Event with some intersting twists.


Asteroid Impact Fueled Global Rain of BBs
Science - SPACE.com/LiveScience.com
Michael Schirber
Staff Writer SPACE.com

The asteroid that struck the Yucatan Peninsula 65 million years ago presumably initiated the extinction of the dinosaurs. The huge collision also unleashed a worldwide downpour of tiny BB-sized mineral droplets, called spherules.

The hard rain did not pelt the dinosaurs to death.

But the planet-covering residue left behind may tell us something about the direction of the incoming asteroid, as well as possible extinction scenarios, according to new research. The falling spherules might have heated the atmosphere enough to start a global fire, as one example.

How the spherules formed in the first place, though, has been a bit of a mystery. One theory is that these half-millimeter-wide globules precipitated out of a giant cloud of vaporized rock that circled the planet after the collision.

"That vapor is very hot and expands outward from the point of impact, cooling and expanding as it goes," said Lawrence Grossman of the University of Chicago. "As it cools the vapor condenses as little droplets and rains out over the whole Earth."

Grossman and Denton Ebel, from the American Museum of Natural History, have shown that this vapor condensation model is consistent with data taken from spherules around the world.

The scientists also found that chemical differences in spherules from the Atlantic and Pacific Ocean imply that the vapor plume initially moved east, which might pinpoint the arrival direction of the asteroid.

Apocalyptic fireball

The spherules populate a three-millimeter layer, called the K-T boundary, which separates the Cretaceous from the Paleogene (formally called the Tertiary) geologic periods. The abrupt disappearance of dinosaur fossils - as well as many marine life fossils - above this boundary implies a major extinction event occurred 65 million years ago.

Around this same time, a city-sized asteroid landed near the present-day town of Chicxulub, Mexico, where traces of a 100-mile-wide crater can still be found.

There is evidence for the asteroid in the unique mineral content of the KT boundary - specifically a high concentration of iridium. This heavy element is very rare on the Earth's surface but is found in high quantities in meteorites.

The implication is that the energy released in the collision fueled a fireball of vaporized rock that rose above the clouds. In this way the asteroid's contents - as well as the material at the crash site - were dispersed across the globe.

"The [KT] layer is thought to be the fallout from the fireball," Grossman told Space.com in a telephone interview.

Included in this fallout were glassy spherules, which have been largely transformed due to weathering, but still contain 100s of spinels - tiny mineral deposits with magnesium, iron and nickel.

"One reason the spinels are important is that most of the original minerals in the spherules are all gone - turned into clay," said Frank Kyte from UCLA, who was not involved in this work. "The spinels appear to not have been altered."

Oxidizing environment

Because of their pristine state, scientists have studied the spinels in hopes of learning about the cataclysm that created them. One such study concluded that - because the spinels contain metal oxides - they could not have precipitated out of the vapor plume up above the atmosphere.

"The argument is silly," Grossman said.

He knows this because the conclusion drew on his own work describing how spinels are created in meteorites. These spinels formed long ago in the pre-planet gas that surrounded the Sun. This gas was mostly hydrogen, so it makes sense that very little oxides - metals bonded with oxygen atoms - are found in meteorites.

But the vapor plume was a different story.

"When you vaporize rock, there is very little hydrogen - whereas 50 percent of the atoms in a rock are oxygen," Grossman said.

As described in the upcoming April issue of the journal Geology, Grossman and Ebel performed computer simulations that showed that the spinels in the KT boundary - with their high concentration of oxides - are consistent with formation inside a liquid droplet condensing out of the impact plume.

These droplets solidified into the spherules, which - according to Kyte - all fell to the ground in a matter of hours or days.

Plume's weather front

A more detailed analysis of the spherules shows that some of them formed earlier than others.

"The spinels that are found at the Cretaceous-Paleogene boundary in the Atlantic formed at a hotter, earlier stage than the ones in the Pacific," Ebel said.

This implies that the cloud of vaporized rock moved east following the collision - a fact that may provide hints as to how the asteroid hit the Earth. This is important because different sorts of debris get thrown into the sky, depending on whether the asteroid came in at an angle or straight down. A complete picture of the impact's geometry and its immediate consequences should help answer questions concerning the eventual effects on the planet's living creatures.

This article is part of SPACE.com's weekly Mystery Monday series.

Catastrophe Calculator
Mystery of the Chicxulub Crater
The Odds of Dying

#26 Lazarus Long

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Posted 02 June 2006 - 12:13 PM

This thread deserves a bump and more because this appears to have happened not once to this world but multiple times. It not only has happened with apocalyptic impact that ended whole ages of life on Earth but has happened with subtle, more local impacts that may have influenced human history.

Well another major transition (Permian/Triassic) is now linked to a significant impact and the crater has been located under the Antarctic ice.

Giant Crater Found: Tied to Worst Mass Extinction Ever

Robert Roy Britt
Senior Science Writer
Thu Jun 1, 8:00 PM ET

An apparent crater as big as Ohio has been found in Antarctica. Scientists think it was carved by a space rock that caused the greatest mass extinction on Earth, 250 million years ago.

The crater, buried beneath a half-mile of ice and discovered by some serious airborne and satellite sleuthing, is more than twice as big as the one involved in the demise of the dinosaurs. (excerpt)

And the issue about complex problems deserving complex analysis I raise elsewhere, is that a debate has raged in paleontology between those that blame vulcanism and those that blamed impacts; while what is most likely is that both occurred. Because crust busting impacts of this magnitude trigger not a single volcanic event but extensive periods of global vulcanism in their aftermath.

When we learn about events such as these we also need to reevaluate the odds of it happening again and as such we should pay attention I suspect to a natural process that has not only once but repeatedly impacted the course of life on Earth.

#27 mikelorrey

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Posted 04 August 2006 - 12:47 AM

I read an interesting paper asserting that accelerated expansion is actually a universe headed toward a big crunch, and that red shift is a representation of distance in time-space, but cannot indicate any absolute velocity.

#28 biknut

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Posted 15 November 2006 - 02:12 AM

This is an interesting story about a recently discovered impact crater in the Indian Ocean. The timing seems to be about right to have maybe caused the biblical flood.

The scientist's that have made the discovery are saying we may need to rethink our beliefs about how often a major impact occurs.


#29 vortexentity

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Posted 15 November 2006 - 03:39 AM

I think that NEOs are interesting real estate for colony projects. Diverting them into stable L5 orbits would be a lot better than just deflecting them. The idea of an asteroid that is kilometers across hitting the Earth is pretty bad, but the idea of a new satellite that size in a stable orbit is pretty attractive. There are also some NEOs that are not likely to hit Earth but their orbit makes them a good potential for a shuttle to Mars. I have found several like that in fact searching the NEO database at NASA.

I think that the technology work being done on the Plasma Sail could be used for the purpose of altering the path of asteroids to cause them to go where we want them. This is done by creating an artificial magnetosphere and then filling this with a charged gas plasma field that obtains a charge from colliding with Solar wind. The magnetic field can be moved around to move the sail for tacking maneuvers.

The work being done is a long way away from this advanced level and likely has not been considered for this application most likely. I think it offers the best potential method of using an asteroid like a space colony ship.

Below is an artist rendering of such an asteroid colony using a plasma sail. The plasma sail also can serve as a plasma shield protecting the colony from charged particle radiation and micro-meteoroids.

Posted Image

Asteroid Colony Ship

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#30 Shepard

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Posted 18 March 2007 - 07:39 PM

Interview w/ Philippe Van Nedervelde on The Space Show


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