AFP - Getty Images file
Atlantis, shown here during a 2006 landing, is due for retirement in 2010.
NASA has set the dates for the space shuttle fleet's final missions, ending with a shipment of spare parts for the space station on May 31, 2010. That schedule isn't set in stone, however – particularly if Congress has anything to do with it.
The space agency wants to get its flights wrapped up by the end of 2010 so that it can turn its attention and its funding more fully to the development of its next-generation Ares rockets and Orion crew vehicle. Even with the shuttle fleet retired, it will take until 2015 or so to get Orion flying, which would represent a giant leap in NASA's renewed push for moon exploration.
Some space pioneers - including the three past and present lawmakers who have flown in space as well as the last man on the moon, Apollo 17 commander Gene Cernan - say Congress should provide more money to keep the shuttles flying after 2010 if necessary. However, NASA and the White House have resisted extending shuttle operations, saying that would cost too much.
Right now, Congress is concerned with one missing mission in particular: a shuttle flight to deliver the Alpha Magnetic Spectrometer, or AMS, to the international space station. AMS would seek out evidence of dark matter, antimatter and other exotic phenomena in Earth orbit. The $1.5 billion, 15,000-pound experiment, backed by a 16-nation collaboration, has been ready to go for years. But it's been bumped from the shuttle flights so that NASA can concentrate on finishing up space station construction.
Last month, the House approved a bill adding $150 million to NASA's budget for an extra shuttle flight to accommodate the spectrometer. A Senate committee approved a bill with different wording, and that means the two versions would eventually have to be reconciled.
NASA doesn't like the idea of being forced to fly an extra mission - particularly if it means keeping the shuttle fleet's huge infrastructure in place. NASA Administrator Mike Griffin told Congress that the cost of extending the shuttle contracts could run into billions of dollars.
However, if all the financial details can be worked out, the AMS mission could conceivably lift off sometime after Endeavour's resupply mission winds up in June 2010. Or the shuttle manifest could be rejiggered, just as it was to accommodate October's scheduled Hubble repair mission.
In any case, it wouldn't be surprising if the launch schedule announced this week slipped every once in a while. In fact, when you consider that this actually is rocket science, it would be shocking if the last mission actually took off on May 31, 2010. With that caveat in mind, here's the launch lineup for the last 10 missions:
So what happens after the shuttles are retired? The expectation is that they'd be parceled out to space centers and museums around the country. The Smithsonian's National Air and Space Museum is tops on the list. And you'd think that NASA's Kennedy Space Center in Florida and Johnson Space Center in Texas would be in line for the other two flown shuttles. But the picture is actually more complex, and already rife with politics, said Robert Pearlman, editor of the CollectSpace Web portal for space history and memorabilia.
"It's become somewhat of a tug of war," he told me.
The best guess is that the Smithsonian would take Discovery, the oldest shuttle, which flew both of NASA's "Return to Flight" missions. That leaves Endeavour and Atlantis ... and Enterprise, the test shuttle that is currently housed at the Smithsonian but would likely become a hand-me-down item.
According to Pearlman, the places working to snag a shuttle include NASA's Florida and Texas centers as well as:
CollectSpace has a whole discussion forum devoted to shuttle lust. But all the uncertainty could be resolved well before the orbiters are retired. Pearlman noted that the same bill providing funding for the AMS delivery has a clause that would address the shuttles' ultimate fate.
"Within 90 days of that bill's enactment, NASA has to come before Congress with a plan to dispose of the shuttle program's hardware, including the orbiters," he said.
For the precise language, check out Section 612 in the full text of H.R. 6063. For a look at the shuttle fleet's past missions, check out our clickable timeline. And just for fun, feel free to enter your prediction below for when the final shuttle mission will actually take off (date and time). To make things fair, we'll consider only those guesses submitted before Dec. 31, 2008.
In 2010, we'll be able to look back at this item and find out who came closest to the mark - and I have a feeling we'll be able to scrounge up a nice bit of future shuttle memorabilia for the winner.
Update for 12:40 a.m. ET July 9: A lot of commenters are asking how the space station's supplies and crews will be transported between the shuttle fleet's scheduled retirement in 2010 and the advent of the Orion/Ares system in 2015. That's a big issue for NASA: The plan is to use spaceships from Russia as well as the Europeans and perhaps the Japanese. There's also a program to support the development of private-sector spaceships capable of reaching the station.
The spaceflight gap is discussed in this article from last year, but since then there have been some changes: SpaceX is still on track to build an orbital launch system based on its Falcon 9 rocket and Dragon capsule, but Rocketplane Kistler had to put its plans for the K-1 rocket on hold, and now Orbital Sciences is getting NASA money to work on its Cygnus/Taurus system. I focused on this private-enterprise angle in a Log posting last month.
AFP - Getty Images
|A foot-wide stone tablet is said to bear Jewish
messianic messages from the first century B.C.
Scriptural scholars are abuzz over a stone tablet that is said to bear previously unknown prophecies about a Jewish messiah who would rise from the dead in three days. But there are far more questions than answers about the tablet, which some have suggested could represent "a new Dead Sea Scroll in stone."
Do the tablet and the inked text really date back to the first century B.C., as claimed? Where did the artifact come from? Can the gaps in the text be filled in to make sense? Is the seeming reference to a coming resurrection correct, and to whom does that passage refer? Finally, what impact would a pre-Christian reference to suffering, death and resurrection have on Christian scholarship?
Such questions are being addressed this week in Jerusalem, at an international conference marking the 60th anniversary of the Dead Sea Scrolls' discovery. They're also being addressed in reports about the "Vision of Gabriel" tablet that have trickled out over the past few months.
That trickle flooded onto the front page of The New York Times on Sunday, in a story that quoted one professor as saying some Christians would "find it shocking" that Jewish scriptures prefigured Christian theology.
But Hershel Shanks, founder of the Biblical Archaeology Society and editor of the Biblical Archaeology Review, said that such a linkage really isn't surprising, let alone shocking.
"The really unique thing about Christian theology is in the life of Jesus - but in the doctrines, when I was a kid, you had little stories about the Sermon on the Mount and the people listening to this saying, 'What is this man saying? I never heard anything like this! This is different,'" Shanks told me. "Today, this view is out. There are Jewish roots to almost everything in Christian experience."
This revised view comes through loud and clear in the Dead Sea Scrolls, which chronicle the spiritual and even the sanitary practices of a Jewish sect that existed around the time of Jesus. It was the similarity to the style of the scrolls that first brought the "Vision of Gabriel" tablet to the attention of archaeologists.
How the tablet came to light
The 1-foot-wide, 3-foot-tall (30-by-90-centimeter) tablet has a checkered past: According to the tale that has been woven around the stone, it was found near Jordan's Dead Sea shore and sold by a Jordanian dealer to Israeli-Swiss collector David Jeselsohn a decade ago. A few years ago, Jeselsohn showed the stone to Ada Yardeni, an expert on ancient Semitic scripts, who consulted with another expert, Binyamin Elitzur.
Yardeni's take on the tablet, published in the Hebrew-language journal Cathedra and in the Biblical Archaeology Review, was that the text was of a style going back to the late first century B.C. or the early first century A.D. - right around the time when Jesus would be growing up.
The 87-line text was written in ink, not inscribed in the stone, and it was laid out just the way one would expect on a scroll, in two nearly even columns. "If it were written on leather (and smaller) I would say it was another Dead Sea Scroll fragment - but it isn't," Yardeni wrote.
The text appears to be a set of apocalyptic pronouncements from a personage named Gabriel - hence the name given to the text, "The Vision of Gabriel" or "Gabriel's Revelations." Biblical Archaeology Review has put the Hebrew text as well as an English translation online.
As you'll see by reading the text, there are so many gaps that it's hard to make out exactly what is being said - but even those fragments were intriguing to Israel Knohl, a Biblical scholar at the Hebrew University of Jerusalem.
Back in the year 2000, Knohl had written a book titled "The Messiah Before Jesus," contending that there was plenty of Jewish precedent for the Christian messianic story. When Knohl read the Cathedra article and looked into the tablet further, he saw new evidence for his thesis:
Knohl laid out his case for interpreting Gabriel's vision last year in an essay for the Israeli newspaper Haaretz and wrote up a more scholarly analysis for April's issue of The Journal of Religion (which you can read by following the links from this Web page). He's also due to discuss the tablet this week during the Dead Sea Scrolls conference.
The resurrection-in-three-days angle was the attention-getter for Sunday's Times report. But many steps in the scientific analysis of the tablet still have to be verified, starting with the origins of the stone and the inked text.
"This story has the big caveat of 'where did it come from?'" Mark Rose, online editor for Archaeology magazine, told me. "Someone knows where it came from, someone found it, someone sold it."
The field of biblical archaeology has had its share of controversies over artifacts that may or may not be genuine - most notably the ossuary of James and the "lost tomb of Jesus." Rose said the tablet would have to face the same kind of scrutiny - and could well end up in an archaeological limbo, neither verified nor debunked.
"You want to look at these stories as having to do with faith? Well, there's a lot of faith involved," he said.
Shanks, who was caught up in the earlier debate over the ossuary (a.k.a. the "Jesus box"), has faith that the tablet ultimately will prove genuine. Some of the most exacting judges of antiquities have been taking a close look at the artifact - and the tablet appears to be passing the tests so far.
"I don't think that you'll find any competent scholar who will call it a forgery," Shanks said.
What does it all mean?
Even assuming that the stone tablet (and the ink writing) are accepted as dating back to the first century B.C., scholars will likely struggle over how the scriptural fragments are pieced together. Perhaps the best way to firm up Knohl's textual interpretation is to find parallel texts elsewhere, as others have done with the Dead Sea Scrolls.
Then there's the question of what effect the "Vision of Gabriel" might have on Jewish and Christian belief.
During the troubled times into which Jesus was born, Jews yearned for the rise of a messiah who would emerge as a powerful military leader and throw out the Roman-backed regime.
"You have in Christian theology a very different kind of messiah, a messiah who's going to shed blood and atone for your sins," Shanks observed. "Where the hell did this come from, baby? Are there elements of this in Jewish messianism?"
The Dead Sea Scrolls have already shown that the idea of a suffering messiah was part of the cultural milieu back then. If the tablet's text and its three-day messianic interpretation are verified, it could shrink the theological gap between pre-Christian Judaism and early Christianity even further. But that shouldn't come as a shock, Rose said.
"Is this going to redefine the relationship between Judaism and Christianity? I don't think so," he said.
Believers might say the "Vision of Gabriel" is yet another scriptural foreshadowing of Jesus' actual death and resurrection - while skeptics might say the text provides more evidence that the gospels fit into a tradition of untrue messianic tales.
What do you think? Will the "Vision of Gabriel" become a religious bombshell? Will it fizzle out? Or will it turn out to be just one more interesting twist in the saga of scriptural scholarship? Feel free to weigh in with your comments below.
Update for 10 p.m. ET July 7: For what it's worth, in today's AFP report on the tablet, Knohl is quoted as saying the text could "overturn the vision we have of the historic personality of Jesus." I suspect many of the commenters would contest that claim. An unnamed Israel archaeologist, meanwhile, is quoted as saying, "It's very strange that such a text was written in ink on a tablet and was preserved until now. To determine whether it is authentic one would have to know in which condition and exactly where the tablet was discovered, which we do not."
Update for 11:55 a.m. ET July 8: Keep a watch for the September-October issue of Biblical Archaeology Review, which will have an article by Knohl on the tablet. And if you're intrigued by ancient Jewish lore, you simply have to plug in to the PaleoJudaica blog, which has been covering the "Vision of Gabriel" controversy for months.
Update for 2 p.m. ET July 8: Ben Witherington III, a New Testament scholar at Asbury Theological Seminary, got back to me after his morning seminars on the church fathers and added some insights. Here are the main points:
For more from Witherington about the tablet and its potential significance, check out the discussion on his blog.
NASA / ESA / STScI / JHU
A twisting ribbon of glowing gas marks the point where the expanding blast wave
from a stellar explosion known as SN 1006 is sweeping through.
Two of NASA's Great Observatories present a red-white-and-blue example of cosmic stars and stripes, just in time for the Fourth of July.
The focus of all this patriotic fervor is a stellar explosion whose first flash was seen centuries before the United States was a twinkle in the Founding Fathers' eyes: The supernova remnant SN 1006 represents what's left over from a blast witnessed by observers from Africa to Europe to the Far East in the year 1006.
The star that blew up was 7,000 light-years away in the constellation Lupus. Scientists speculate that it was the brightest observed supernova in recorded history, blazing with a light that could be seen in the daytime sky for weeks afterward. (Other supernovae may have been intrinsically brighter, but we're talking about how they were seen on Earth.)
The supernova sent out a shock wave that expanded at an average rate of nearly 20 million mph. In the 1960s, radio astronomers first detected the ring of material that was pushed out by that wave. Since then, telescopes have done even better, charting the edge of the shock wave in multiple wavelengths.
As the wave moves out, it lights up the thin hydrogen gas surrounding the star - and that rippling glow is what's chronicled in the latest imagery released by the Hubble Space Telescope's science team. A close-up view of the wave front looks like a gossamer red stripe with starlight shining through it.
If you compare the stripe's position with a picture taken a decade ago from the Cerro Tololo Inter-American Observatory, you'll see that the wave is continuing to move outward at about 6 million mph. For an extra treat, check out the zoomable version of the Hubble view.
NRAO / NASA / CXC / Rutgers / Middlebury / NOAO
|This composite image combines visible-light, radio and X-ray data for the full shell of the supernova remnant from SN 1006. The small green box along the bright filament at the top of the image corresponds to the dimensions of the Hubble release image. Click on the image for a larger version.
The full picture of the supernova remnant has been filled out with data from NASA's Chandra X-Ray Observatory (another one of NASA's Great Observatories), Cerro Tololo, the Digitized Sky Survey and the National Radio Astronomy Observatory. The colors may evoke flags and fireworks, but they don't reflect how the supernova would look to the naked eye. In this case, they're just being used to distinguish the different wavelengths that went into the picture.
Speaking of the naked eye, there's plenty to see in the sky on the Fourth of July - and we're not just talking about fireworks: Science @ NASA shows you how to spot a great grouping of Saturn, Mars and the moon in western skies this weekend, with the bright star Regulus in a supporting role. Consider it a warmup act for the Saturn-Mars close encounter on July 10.
If you're a morning person (as in, um, 4 a.m. or so), you can watch for the international space station passing overhead this weekend: NASA's real-time satellite tracking site can tell you exactly when the orbital outpost will be visible.
If you're really lucky (and early), you'll catch a glimpse of Comet Boattini. Tony Flanders sizes up the comet for Sky & Telescope. "Few people are likely to see the comet without optical aid, but it should be pretty easy to spot through binoculars as long as your light pollution isn't too bad," he writes. Check out the detailed viewing chart.
Looking ahead, we're starting to get into the summer season for meteor observing. After this weekend's fireworks, keep an eye on the skies for stray shooting stars. A couple of meteor-watchers have noticed stronger-than-expected activity over the past couple of nights. The Delta Aquarids are due to heat up later this month, and the Perseids will hit their peak on Aug. 12. Now there's a fireworks show worth waiting for.
Science Debate 2008 couldn't quite pull off a political debate on science and technology issues during the presidential primary season, but the big contest is still ahead of us. This week, the effort's organizers laid out a list of 14 questions to focus the discussion for the next four months. The questions make clear that the sci-tech debate isn't just the province of lab-coated geeks, but touches upon society's most important issues.
The questions have been submitted to the top presidential candidates, with the request that they provide written responses and address the questions in a nationally televised forum. Any answers received will be posted on the Science Debate 2008 Web site. But the questions are too good to reserve for the candidates alone. They deserve to be addressed by the public as well. Here's the rundown:
1. Innovation. Science and technology have been responsible for half of the growth of the American economy since WWII. But several recent reports question America's continued leadership in these vital areas. What policies will you support to ensure that America remains the world leader in innovation?
2. Climate Change. The Earth's climate is changing and there is concern about the potentially adverse effects of these changes on life on the planet. What is your position on the following measures that have been proposed to address global climate change — a cap-and-trade system, a carbon tax, increased fuel-economy standards, or research? Are there other policies you would support?
3. Energy. Many policymakers and scientists say energy security and sustainability are major problems facing the United States this century. What policies would you support to meet demand for energy while ensuring an economically and environmentally sustainable future?
4. Education. A comparison of 15-year-olds in 30 wealthy nations found that average science scores among U.S. students ranked 17th, while average U.S. math scores ranked 24th. What role do you think the federal government should play in preparing K-12 students for the science- and technology-driven 21st century?
5. National Security. Science and technology are at the core of national security like never before. What is your view of how science and technology can best be used to ensure national security, and where should we put our focus?
6. Pandemics and Biosecurity. Some estimates suggest that if H5N1 Avian Flu becomes a pandemic it could kill more than 300 million people. In an era of constant and rapid international travel, what steps should the United States take to protect our population from global pandemics or deliberate biological attacks?
7. Genetics research. The field of genetics has the potential to improve human health and nutrition, but many people are concerned about the effects of genetic modification both in humans and in agriculture. What is the right policy balance between the benefits of genetic advances and their potential risks?
8. Stem cells. Stem cell research advocates say it may successfully lead to treatments for many chronic diseases and injuries, saving lives, but opponents argue that using embryos as a source for stem cells destroys human life. What is your position on government regulation and funding of stem cell research?
9. Ocean Health. Scientists estimate that some 75 percent of the world's fisheries are in serious decline and habitats around the world like coral reefs are seriously threatened. What steps, if any, should the United States take during your presidency to protect ocean health?
10. Water. Thirty-nine states expect some level of water shortage over the next decade, and scientific studies suggest that a majority of our water resources are at risk. What policies would you support to meet demand for water resources?
11. Space. The study of Earth from space can yield important information about climate change; focus on the cosmos can advance our understanding of the universe; and manned space travel can help us inspire new generations of youth to go into science. Can we afford all of them? How would you prioritize space in your administration?
12. Scientific Integrity. Many government scientists report political interference in their job. Is it acceptable for elected officials to hold back or alter scientific reports if they conflict with their own views, and how will you balance scientific information with politics and personal beliefs in your decision-making?
13. Research. For many years, Congress has recognized the importance of science and engineering research to realizing our national goals. Given that the next Congress will likely face spending constraints, what priority would you give to investment in basic research in upcoming budgets?
14. Health. Americans are increasingly concerned with the cost, quality and availability of health care. How do you see science, research and technology contributing to improved health and quality of life?
As we go into the holiday weekend marking America's independence, the prospects for future advances in science and technology are mixed. The problems we're facing - ranging from global climate change and national energy dependence to international competitiveness - aren't getting easier, but at least they're getting more attention.
On the basic-research front, the outlook is somewhat less gloomy than it was six months ago: A spending bill signed into law this week restores some of the research funding that was axed by Congress last December, including $62.5 million for the Energy Department's science programs. That will ease some of the pain for the Fermilab particle-physics center and other federal research facilities, but it won't put everything back the way it was. (The American Institute of Physics provides added perspective.)
How do you view the science scene? Where do you stand on the 14 questions? Is the lab beaker half-empty or half-full? Please feel free to add your comments below.
Have yourselves a fantastic Fourth of July. I'll be taking the day off, and I'm aiming to resume regular postings on Monday. Here are a few links to get you through the long weekend:
|A simulation shows the pattern of
particles that scientists think could
be produced by a micro black hole.
What good is a microscopic black hole, and why would you make one on Earth? Can a black hole ever really be safe, even if it's the size of a quark?
Michelangelo Mangano is a theoretical physicist at Europe's CERN particle-physics center, where black holes could conceivably be created as early as next year, and such questions have taken up his time for many months.
In an exclusive Q&A, he provides answers on a cosmic scale.
Mangano is one of the authors of CERN's latest safety report for the Large Hadron Collider, which is destined to become the world's most powerful atom-smasher. The 17-mile-round underground ring on the French-Swiss border is being readied for its official startup next month or so, but the proton-on-proton action isn't likely to reach its peak energy of 14 trillion electron volts, or 14 TeV, until next year.
At that level, there's a chance that the LHC might create microscopic black holes - as well as supersymmetric dark-matter particles, quark-gluon plasma, the elusive Higgs boson (a.k.a. the "God Particle") and other exotic stuff. It was Mangano's job to update past safety reports that concluded particle colliders like the LHC posed no risk of sparking a cosmic catastrophe (for example, creating the planet-gobbling variety of big black holes).
Those previous studies took the view that micro black holes would almost instantly wink out of existence, based on the claim that black holes lost energy through a phenomenon called Hawking radiation. But critics complained that the evidence for Hawking radiation was less than rock-solid - and for that reason, a couple of those critics filed a federal lawsuit seeking the suspension of work on the LHC.
Courtesy of M. Mangano
is a physicist at CERN.
Answering that criticism, Mangano and a colleague of his from the University of California at Santa Barbara, Steve Giddings, wrote a heavy-duty research paper asserting that the LHC posed no catastrophic risk, even if you assumed that micro black holes remained stable and didn't emit Hawking radiation. The Giddings-Mangano study, or "GM paper," drew high praise from a panel of experts who endorsed CERN's safety report.
The most dedicated critics may not be satisfied, but Mangano hopes that the latest findings should reassure reasonable observers that particle colliders pose no threat. The Italian-born 46-year-old also hopes that he can now get back to some semblance of a normal life, although I have a feeling he's going to be kept busy at least until the LHC reaches its top energy of 14 TeV.
This week, Mangano discussed in detail what led him to conclude that Earth was safe - and explained how microscopic black holes could spark a scientific revolution. Here is an edited transcript:
Q: What new research did you conduct on this question about what the Large Hadron Collider will do, and how does it apply to this controversy over black holes?
A: We took on the suggestion that black holes could be stable, even though the overwhelming majority of experts don't take this as a serious possibility. It's quite clear, if you just do some simple estimates, that even in the scenario in which black holes are stable, you should be able to rule out any possible problem. Anything that could destroy the earth cannot just happen on earth, it would have to be able to happen somewhere else. So we just went around and identified what seemed to be the most promising systems we could look at, to establish this connection. In fact, many scenarios can be ruled out directly by the fact that they would have already destroyed the earth or the sun. But for certain scenarios you need to consider other objects.
Dense objects like white dwarfs and neutron stars seemed to be the best possible candidates, because they're very dense, and therefore if you produce black holes from cosmic rays, they would be stopped by those objects. Since they are dense, the black hole would eat matter at the highest rate. It would tend to consume such objects much faster than it would consume the earth. So we studied how stable black holes would change lifetimes of these objects.
The crucial point is this: The black holes that could be produced by the LHC would be very, very small objects. Now, the black hole absorbs matter that gets in its way, right? If you assume that the black hole only eats whatever falls into its trajectory, you find out that it would take a nearly infinite amount of time before it could do any damage to earth. It just cannot grow fast enough, because it's too small.
The only way that you could actually do something macroscopic is by drawing in matter from a much, much larger distance. Since this is the condition under which a black hole can become dangerous, and since it requires the distance at which it affects the matter surrounding it to be large, you only need to understand very basic features of how a black hole works. The starting point for this research is to assume our ignorance about the quantum state of a black hole – whether it's stable, whether it decays, whether there is Hawking radiation.
We know that in order for the black hole to do anything macroscopic, it has to behave as a big object. It has to have an effect at a large distance. But at a large distance, we don't worry about the microscopic state of a black hole. It's all electromagnetism, it's fluid dynamics, it's the standard physics that we know very well.
We can arrive at very solid conclusions that do not presume knowledge of physics beyond the Standard Model on a microscopic scale. This is the main contribution, if you wish, of our work – aside from working out the implications of these observations in detail.
Q: But how did you match up your conclusions about the macroscopic effects of a black hole with observations of the universe itself? Did you do a survey of neutron stars?
A: We know what the rate of cosmic rays is, how they permeate the galaxy. Then we look at very specific neutron stars or, better yet, white dwarfs. We're not doing a statistical analysis. We're merely looking at a specific object. And we ask ourselves, "How long has that object been there?" For example, we have a very reliable estimate of the age of a white dwarf, based on its temperature and mass – macroscopic parameters that are well-measured and well-understood by astronomers.
And then we ask, "How many cosmic rays with energy beyond the energy of the LHC have hit that star, and how many black holes would have been produced inside that object, if black holes can be produced at the LHC?" We find numbers that are very large – numbers that are in the hundreds, in the thousands.
In parallel, we calculate how long one of these black holes would take to destroy that object. And we find numbers that are on the order of anything between a few years and perhaps a hundred thousand years or 1 million years. It's basically impossible that this star had not been hit by a cosmic ray that would have produced a black hole. And if it produced a black hole that was capable of consuming the star, the star would be gone. It would not be there.
Q: Maybe we can back up a bit and ask how a microscopic black hole is created in a particle accelerator. Does the impact of the protons lead to the gravitation collapse of a particle to such a degree that it creates a black hole, like a star collapsing? Or is it a different mechanism?
A: It's slightly different. Two quarks – one quark from one proton, the other from the other proton – come together with the very high energy that they inherit from the protons that contain them. They come very, very close to each other. From Einstein's theory of general relativity, we know that it's the energy density that curves spacetime. It's the mass in E=mc2. If you have mass, or you have energy, it's the same. So if you manage to concentrate enough energy in a very small amount of space, then you curve spacetime, and beyond a given curvature you create a small spatial region that we call a black hole.
This isn't like the collapse of a star, where you have no radiative pressure after running out of fuel and it falls onto itself under its own gravitational field. Here, it's shooting two particles very close to each other at very high energy to create this huge energy density.
Now, if we just have the universe as we currently know it, in order to create such a spacetime region, it would require an amount of energy that is 1 million billion times bigger than the LHC. That's energy on the order of 1019 GeV [giga electron volts] – much higher than anything that is achievable today.
On the other hand, some speculative theories say that there are more dimensions in addition to the four dimensions of the regular universe we know. If those theories are true, then the force of gravity could become much stronger at very short distances. The gravitational force between these two particles would become much bigger. Therefore, there would be a much higher potential for curving spacetime and producing this black hole even with energies as low as those accessible at the LHC.
So in order for the LHC to produce some of these black holes, we really have to go beyond the normal theory of gravity. We have to assume that there are extra dimensions. By the way, there are many theories that have extra dimensions. Not all of them would give rise to black holes at the LHC. It's only highly fine-tuned ones that make this possible.
Q: How would these black holes be detected? I assume that you wouldn't detect them directly, but you'd detect them through their decay products.
A: This is true of pretty much every particle that we produce at this accelerator. Even the top quark is not detected directly, because it decays within 10-24 seconds. What we see are the decay products. It'd be the same for a black hole. It would decay on a time scale that is about a factor of thousands smaller than that of the top quark. The main feature of a black hole decay is that there would be no bias in the particles coming out of the decay.
The final state would be relatively spherical, with no specific direction. There'd be a uniform distribution, with many highly energetic particles of all different kinds: electrons, muons, quarks, photons. This is something that the typical proton-proton collision would not give rise to. It would be a very distinctive signature.
Q: Is there any expectation of how long it might take to have a confirmed detection of black holes? Does it usually take a couple of years?
A: This would be a very spectacular signature. The number of events would be quite large. So it's not unreasonable that two or three years could be enough to draw this conclusion. It all depends on the mass, because if the black holes exist, they cannot be arbitrarily light. Otherwise we would have seen them already at the Tevatron.
We haven't seen them at the Tevatron, so they have to be at least a few TeV. In fact, from other collider limits on extradimensional gravity, we know they must have mass higher than about 5 TeV. If they are close to this, their production rate would be large, and they would be produced abundantly early on. Given the spectacular nature of the final state, I believe there could be a conclusion within a couple of years.
In fact, it could be easier than detecting the Higgs boson. We talk a lot about the Higgs, but the Higgs is not the simplest thing to observe. Supersymmetry could be discovered before the Higgs. Extra dimensions and black holes could be discovered before the Higgs.
Q: And because black holes would imply that extra dimensions exist, that would be a signal achievement for physics. Would that provide the first evidence that all this crazy talk about extra dimensions is true?
A: That would certainly be the most compelling indication that indeed we live in more than four dimensions. Philosophically, that would be at the same level as special relativity or quantum mechanics. That would be a major revolution in our view of the universe – well beyond the Higgs, well beyond supersymmetry and anything else that we have thought of.
Q: I know this is the question that physicists hate, but would there be any implications for daily life? Could extra dimensions lead to new energy sources, for example?
A: I really have no idea what we could get out of extra dimensions. But there is one element of our universe that we don't understand very well, and that is gravity. Being able to do experiments exposing extra dimensions would for the first time provide us with a new observatory for gravity.
So far, the only place where we can measure gravity is in the macroscopic universe, where we measure the motion of planets and other large objects, or the expansion of the universe itself. But it all follows from the same law of gravity: Newton's law or, if you wish, Einstein's theory of general relativity. By looking at how spacetime works at very short distances, we get an entirely different picture. God knows what we will uncover.
All of these discussions about traveling forward and backward in time, or wormholes, you name it – all of these ideas, however bizarre, if they work at all, could be exposed by phenomena in the framework of extra dimensions.
When we're talking about the proton-proton collisions at the LHC, one manifestation of extra dimensions would be the production of black holes. Maybe there are other manifestations. Maybe you could alter the fabric of spacetime, for example. But again, the risk is something we can rule out, because destroying the fabric of spacetime is not something that would happen only at the LHC. If you look at the much more energetic cosmic-ray collisions taking place out there in the universe, if any of those had created a problem with spacetime, we would know it by now.
So when I say "we don't know what will happen," it doesn't mean we have a new source of uncontrollable risk. I'm simply saying that the picture of the universe that we will see could be very interesting.
You know, 5 billion years from now, the sun is going to blow up. There is nothing we can do about that. This will be worse than global warming. It will be worse than a meteorite hitting Earth. If we want to survive for more than 5 billion years, we have to find a way out of this place – and the way to get out of this place is not just by building more powerful rockets. We have to understand more about spacetime and how to travel in a much more efficient way.
I'm not saying this will come out of the LHC. But it's quite clear that, if it finds black holes, the LHC will be one of the steps in this direction.
N. Moeller / Tell Edfu Project
This view of the excavation at Tell Edfu shows superimposed
settlement layers. Some of the grain silos from Egypt's 17th Dynasty
were covered by a thick layer of ash. At a later date, several storage
compartments were built on top of the covered silos.
Egypt's best-known excavations usually focus on the glittering mummies and grand monuments of the pharaohs, but for something completely different, travel up the Nile to Tell Edfu: The archaeologists digging there have uncovered ruins that shed light on the administrative and agricultural foundations of ancient Egypt's riches.
G. Marouard / Tell Edfu Project
|The Tell Edfu archaeological dig is spread out in the
foreground, with the pylon of a Ptolemaic temple in
the background. Click on the image for a larger view.
The Tell Edfu site is significant because it preserves about 3,000 years' worth of history in a single mound - and because the ancient settlement served as a key link in the chain connecting Egypt's agricultural society with the lifestyles of the rich and famous.
"The problem has been that my colleagues deal with temples and monumental architecture, and settlements haven't been something that has attracted that level of interest," the dig's director, University of Chicago archaeologist Nadine Moeller, told me. "But they're actually really important for understanding the ancient Egyptian civilization."
Many of ancient Egypt's urban sites have gone by the wayside, obliterated either by farming or by centuries of urban renewal. So little evidence has survived that some scholars question whether Egypt ever had a well-developed urban culture, according to today's report from the University of Chicago about the Tell Edfu dig.
A granary ... and a bank
Moeller and her colleagues excavated what amounted to the downtown area in a provincial capital, south of ancient Thebes (modern-day Luxor). Thebes is hundreds of miles upstream on the Nile from the Great Pyramids - but for long stretches of Egypt's history, the city served as a pharaonic capital.
Among the most intriguing structures excavated so far are seven grain bins dating back to the 17th Dynasty (1630-1520 B.C.). Because grain served as a form of currency, this wasn't merely a granary - it was also the ancient equivalent of a bank, essentially managing tax collections for the provincial governor and the pharaoh.
D. Farout / Tell Edfu Project
Nadine Moeller of the University of Chicago's Oriental Institute supervises
the Tell Edfu dig. Click on the image for a larger version.
"Grain as currency provided the sinews of power for the pharaohs," Gil Stein, director of the Oriental Institute at the University of Chicago, explained in today's news release.
The administration of that power has been described in ancient Egyptian texts, but there's nothing like seeing the actual places where that power was exercised. The silos measure 18 to 21 feet wide, making them the largest grain bins ever discovered within an ancient Egyptian town center.
Yet another layer of construction predated the silos. Moeller and her colleagues determined that a mud-brick structure with 16 wooden columns was used in the 13th Dynasty (1773-1650 B.C.), based on an analysis of shards of pottery and scarab seals found at the site. The hall of columns served as a place where scribes did their accounting, opened and sealed containers, and received letters.
G. Marouard / Tell Edfu Project
|This view of the ruins of a 13th-Dynasty
administrative building shows some of
the sandstone column bases.
Moeller speculated that the hall may have been part of the provincial governor's palace. "It was far more extensive than we expected," she said. "Actually, I still haven't reached the full limit of the whole structure."
For now, the dig has sparked more questions than answers: How much time did the grain spend in the silos? How was it distributed among provincial, priestly and pharaonic officials? What heights did Egypt's urban society reach more than 3,000 years ago? When Moeller returns to the dig in October, she plans to seek the answers to such questions and more.
Tell Edfu may not look as monumental as the Great Pyramids - but the dead city, and other sites like it, are just as important for learning how everyday Egyptians lived. If anything, such sites are more endangered than the pyramids themselves.
"We don't have many of these sites left," Moeller said.