Microsoft co-founder Bill Gates is just the latest name to be dropped as someone who's supposedly interested in buying a multimillion-dollar spaceflight. Microsoft itself says it "makes it a practice not to comment on rumors or speculations," but the report naturally leads us to speculate on who else who's famous has been interested in going up to the final frontier - and why they won't be going up anytime soon.

So far, the most famous (or at least the richest) person to fly to the international space station is the guy who's up there right now: software executive Charles Simonyi, who oversaw the development of Word, Excel and other programs for Microsoft. (In the interest of full disclosure, I should mention that Microsoft is a partner along with NBC Universal in the MSNBC.com joint venture, and that I wrote some of the background material for Simonyi's mission.)

To the general public, Simonyi is probably best known for the company he keeps: He's been socially and romantically linked with lifestyle guru Martha Stewart, who attended last week's launch in Kazakhstan and continued to follow the flight from Russian Mission Control. A story in today's London Telegraph says that Stewart "has managed to steal the limelight" from the space mission itself.

Through the years, quite a few notables have dropped big hints that they might like to take the kind of trip Simonyi is taking. "Titanic" director James Cameron reportedly passed the initial medical exam for cosmonaut training and was negotiating with the Russians to film a movie on the space station.

That deal fizzled out, however, as did a reality-TV project to put 'N Sync pop singer Lance Bass in orbit. (If Bass had gone up on schedule, he might have become the world's youngest space flier and the first cosmonaut to acknowledge publicly he was gay.)

Other big names who have reportedly considered orbital spaceflights include actors Tom Hanks and Tom Cruise, as well as singer-actress Madonna. In fact, Russian legislators tried to push through a space reservation for the now-maternal "material girl" - and I suppose some of Madonna's detractors wish they had succeeded. The list of celebs planning suborbital flights is much longer, ranging from primetime-soap actress Victoria Principal and "Alien" film star Sigourney Weaver to wheelchair-using physicist Stephen Hawking.

"Star Trek" captain William Shatner, in contrast, has backed away from the idea. "I'm interested in man's march to the unknown, but to vomit in space is not my idea of a good time," he famously told The Sun, a British tabloid. "Neither is a fiery crash with the vomit hovering over me."

Shatner may not be on deck for a spaceflight anytime soon, but others are perfectly willing to take the risk. Virginia-based Space Adventures, which booked the flight for Simonyi and the four millionaires who preceded him into orbit, is due to announce its next spaceflight client "in the coming weeks," company spokeswoman Stacey Tearne told me today. That client would fly to the international space station on a Soyuz craft in the fall of 2008, she said.

"We secured seats for '08 and '09," Tearne said.

Meanwhile, the head of Russia's space agency said today that one of the country's governors might go on an orbital space tour in 2009.

Tearne said Space Adventures hasn't heard anything from Gates, and she acknowledged that the clients so far haven't fit the celebrity profile some had thought would dominate the space tourism market. "But I wouldn't discount having that kind of individual in the future," she said.

Most people who are rich and famous have to think twice about committing themselves to an orbital flight - and not just because of the $25 million price tag. That usually isn't the sticking point, Tearne said.

"It hasn't been about the cost," she said. "It's about the time and the availability."

The training schedule requires spending about six months at Russia's Star City cosmonaut complex, and it's hard to get business done or shows made while you're stuck out in the countryside near Moscow.

If you're trying to put together a celebrity deal, the challenges are even harder - as the promoters of Bass' trip found out. Celebrities are used to being paid for their time, rather than having to pay out millions for a TV-worthy experience. The Russians are used to being paid in advance for the training and eventually for the flight itself. But would-be sponsors usually want to see what they're paying for before the checks are signed. They're understandably skittish about paying up front to have their name attached to a potential catastrophe.

Fortunately for Space Adventures, there are lots of people who are rich but not necessarily famous. The company has said it has plenty of prospects for future orbital flights, and Tearne said the offering of a flight around the moon and back for $100 million per seat was attracting interest as well. In fact, Space Adventures is hoping to announce its first round-the-moon client "by the end of this year," she told me.

In the longer run,  the outlook for the availability of Soyuz seats gets hazy - due to the scheduled retirement of NASA's space shuttle fleet in 2010. The demand for seats aboard Russia's Soyuz craft would likely increase, and it's not clear how many of those seats would be available for Space Adventures' paying passengers.

After 2009 or so, it could well be that the best opportunities for orbital flights will come from private-sector suppliers.

Will the first honest-to-goodness celebrity go up on a Soyuz or on a SpaceX Dragon, or a Rocketplane transport, or a PlanetSpace Silver Dart, or a t/Space CXV, or a Russian-built Explorer? Will Bill Gates or Madonna be able to choose between the international space station and a Bigelow-built space module? Those propositions are what the infant spaceflight industry is all about. Lay down your predictions now in our comments section, and we'll find out who's the best prognosticator sometime in the 2010-2015 time frame.

Update for 9:30 p.m. ET April 12: In a previous post about Cosmonauts Day (a.k.a. Yuri's Night), I mentioned that pinot noir might be a good match for the six-course meal that Simonyi is serving on the space station. But then I realized that I knew a real expert on food and wine: Jon Bonné, a former MSNBC.com colleague who is now wine editor at The San Francisco Chronicle. Here are Jon's e-mailed recommendations:

"Pinot, perhaps a fuller-bodied one from California or Oregon, would suit the quail quite well. Though of course a good 10-year Madeira wouldn't be a bad option either. Or a fleshier Syrah.

"The other pick, given the chicken, is a Rhone-style white, perhaps a St. Joseph Blanc, a Tablas Creek Esprit de Beaucastel Blanc or a white Chateauneuf.  Mostly depends on the preparation."

Space gourmets, take note.

Today's a big day for squares, sisters and faces in space ... and we're not just talking about the parties to celebrate Yuri's Night. Researchers explained what gives the Red Square nebula its extremely symmetrical shape, as reported in this story from our partners at Space.com. Meanwhile, NASA's Spitzer Space Telescope has come out with a colorful infrared image of the Pleiades, also known as the Seven Sisters. (I do hope you're able to see Venus and the Sisters in the heavens.) And the Mars Reconnaissance Orbiter has delivered a fresh look at an old favorite, the Face on Mars. Click on the links below for the highlights:

• HiRISE: Orbiter's camera steals a peek at the Face on Mars
• Spitzer takes a feathery picture of the Seven Sisters ...
• ... And sheds light on a mystery of galactic proportions
• CICLOPS: Shifting strands around Saturn

When Soviet cosmonaut Yuri Gagarin blasted off to become the first man in space, his first words after launch were "Let's go!" The phrase takes on a different meaning on Thursday, exactly 46 years later, with 119 parties marking Yuri's Night in 32 countries around the world.

Let's go … to party down with space fliers in New York and Seattle, with space scientists in Washington and San Antonio, or with virtual space residents in Second Life's online realm. Even the international space station is getting into the act, with a six-course gourmet meal to mark the holiday celebrated as Cosmonauts Day in Russia.

Yuri's Night

Yuri Gagarin became the first human in space on April 12, 1961.

Billionaire space passenger Charles Simonyi will break out the roast quail, duck breast and other delicacies - all part of a menu selected by his friend, lifestyle guru Martha Stewart, and prepared by French chef Alain Ducasse. Although alcohol is officially banned on the space station, at least as far as NASA is concerned, this may well qualify as a special occasion to honor Gagarin's legacy with a toast. (Pinot noir is said to go with roast quail, but I suppose a bit of vodka or cognac would serve as well.)

The Cosmonauts Day tradition goes back decades in Russia, but the global Yuri's Night celebration is of more recent vintage: It began in 2001, under the guidance of space activists Trish Garner, Loretta Hidalgo and George Whitesides. Hidalgo (now Mrs. Hidalgo-Whitesides) is executive director of the Yuri's Night organization.

In a pre-party update, Hidalgo highlighted Friday's Bay Area event at NASA's Ames Research Center, where Iranian-American space passenger Anousheh Ansari will be the headliner and virtual-telescope imagery from Slooh.com will be one of the draws. She also cited the bash in Beijing (a first for Yuri's Night) and the zero-gravity-themed hoedown in Houston.

Another hot spot, strangely enough, is Bulgaria. "It's great that Bulgaria has 17 parties this year," she told me. "I'd love to be a fly on the wall in Bulgaria."

As lovely as Sofia must be at this time of year, I'd find it hard to pass up the Los Angeles party, starring George Takei of "Star Trek" fame and science-fiction master Ray Bradbury. Of course, the whole idea behind Yuri's Night is to celebrate the past 46 years of space achievements with art and music - so there'll be plenty of dancing and merrymaking.

This year also marks a first for the Second Life celebration, and that's likely where I'll be hanging out as Boole Allen. If you spot me in the crowd, say hello - but don't ask me to dance. I'm such a newbie that my avatar can barely walk and chew gum at the same time.

So what's next? "I definitely want to see things get bigger and better next year," Hidalgo told me. "I think getting some bigger music acts involved would make a big difference."

Hidalgo also has visions of spreading the Yuri's Night celebration beyond the surly bonds of Earth. "Imagine having events in space," she said. "The Bigelow inflatable Yuri's Night party, or the on-the-moon party."

Sounds good to me. As Yuri said back in 1961: "Poyekhali!"

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World-famous cosmologist Stephen Hawking was in the Seattle spotlight Monday night to explain the big questions: Why does time seem to move always forward but never backward? Why does he think running time backwards the only way to solve the universe's biggest mystery? But the small questions can be just as intriguing: For example, how does Hawking "autograph" a book? When he composes a sentence on his gesture-controlled computer, does he blink or does he sneer?

Here are some insights into those questions, great and small, gleaned during a close encounter with Cambridge University's frail genius:

Kimberly Wright / Reuters file

Physicist Stephen Hawking uses an infrared sensor mounted on his eyeglasses as part of a computerized writing/speaking system.

The title of Hawking's advertised talk was "The History of the Universe Backwards," but he actually delivered two lectures - one looking back at his own career in physics, and another focusing on his latest theories about a "top-down" approach to cosmology.

The first talk touched on the milestones of his career: how he went into cosmology rather than particle physics, the subdiscipline du jour, because he marched to the beat of a different scientific drummer ... how he was diagnosed with a neurodegenerative disease, known as amyotrophic lateral sclerosis or ALS, while he was in graduate school ... and how, despite his increasing disability, he went on to plumb the theoretical depths of black holes and the big bang.

Hawking has gone back and forth about what happens to the things that are sucked into a black hole. At one time, he held that the "information" falling into the black hole is lost forever, but recently he has said that the contents of a black hole would leak out in the form of "Hawking radiation," until the black hole itself dissipates.

"Information is not lost, but it is not returned in a useful way," he said. "It is like burning an encyclopedia. Information is not lost, but it is very hard to read."

Speaking of encyclopedias, Hawking noted that his reversal caused him to lose a bet to a fellow physicist, with the payoff coming in the form of a baseball encyclopedia. "Maybe I should have just given him the ashes," Hawking joked.

It was the second talk that really spurred my interest. Hawking and a colleague from CERN, Thomas Hertog, recently declared that the best way to understand how the universe arose was to look at our current cosmic conditions, then work back through "the sum of all histories" to figure out which theory would produce those conditions.

Hawking calls it a "top-down" approach to what he has long considered the biggest cosmic question: What was the initial state of the universe? Did God just create the universe the way it was, and that's it? Or is there a scientific reason for why the cosmos is just so ... why, for instance, it could lead to the conditions for intelligent beings like us?

Hawking's top-down vs. bottom-up approach goes to the heart of the issue covered in his best-known bestseller: "A Brief History of Time." During his Seattle talk, Hawking contended that cosmologists essentially had to look at time in reverse.

If time is a definite dimension like up-down, left-right and forward-back, why does time only move forward? Hawking said the answer to that question might lie in the Second Law of Thermodynamics - the idea that an enclosed system must move from a more ordered to a less ordered state:

"We don't really know how the human brain works. I find women's brains a particular mystery. But it is reasonable to assume that humans remember the same direction of time as computers do. ... We understand how computers work, unlike humans. And one can show that when a computer records an item in its memory, the total amount of disorder goes up. So computers and humans remember the past, and not the future. That is, because of the Second Law, we usually recount history forward.

"We say that later events are caused by earlier events, but not that earlier events happen in order to lead to the later. This 'bottom-up' approach, as I call it, works well in situations in which we can choose the initial state and observe the outcome. But the bottom-up approach does not work in cosmology.

"We do not know what the initial state of the universe was, and we currently can't try out different initial states and see what kinds of universes they would produce."

General relativity alone can't solve the problem, so quantum mechanics has to come into play to figure out what's the likeliest backward history for our universe, Hawking said.

As we've mentioned before, the twists in mathematics that link up general relativity and quantum mechanics seem to imply that we live in an 10- or 11-dimensional universe, perhaps with up to seven dimensions somehow rolled up into immeasurably small loops. The math also implies that there is a virtually immeasurable number of ways that our universe could have developed - nearly driving theoreticians to despair.

Hawking, however, isn't the despairing type: He said physicists should focus just on the scenarios that have three large spatial dimensions, like ours. It may sound like the anthropic principle - that is, the view that the universe is the way it is simply because there would be no intelligent life around to observe it if things were much different. But Hawking preferred to use another term - "the selection principle" - because the selection "doesn't depend on intelligent life."

That's not to say the loop dimensions don't count. Hawking said those other dimensions, which he called "internal space," may well determine the fundamental characteristics of our cosmos, such as the charge of an electron or the nature of subatomic interactions.

So how can physicists work their way backwards and map out that internal space? Strangely enough, Hawking endorsed the same approach favored by Columbia physicist Brian Greene, an earlier speaker in the Seattle lecture series: looking closely at irregularities in the "fingerprint" of the early universe, as seen in the background radiation left behind by the big bang. Those irregularities, which could soon be mapped in greater precision by probes such as the Planck spacecraft, may reveal the imprint of our own internal space.

Hawking said that the universe may represent just one "bubble" in a cosmic froth - perhaps longer-lasting than some other blips. Rather than dwelling so much on how many other unseeable bubbles there could be, Hawking advised concentrating on what makes our bubble the way it is.

"There seems to be a vast landscape of possible 'internal spaces,'" he said, setting up for a final joke. "We live in the anthropically allowed region, in which life is possible. But I think we might have chosen a better location."

I met Hawking at a reception after the talk, and here are some impressions on those smaller questions at the beginning:

• If you want to get on Hawking's good side, stand to his right. That's the natural direction of his gaze when he's fixed in his wheelchair, and the tiny infrared sensor that he uses for his computerized communication system is mounted on the right temple of his eyeglass frames. For the record, he wore an open-neck, striped dress shirt, brown suit jacket and slacks, and brown suede shoes for Monday's talk. His hands were composed in his lap, and he was attended by two British assistants.
• The system Hawking uses to compose the phrases for his mechanical voice is often called a "blink-controlled" computer, but I'd call it more of a twitch or a sneer. Not that there's anything wrong with that. He raises his upper lip over his teeth for an instant, and the cursor on his wheelchair-mounted computer screen jumps. First, Hawking highlights a block of words, then a row, then the desired word or letter sequence to add to his sentence. Each twitch of the lip and cheek is acknowledged by a beep of the computer.
• Long lectures are pre-written, of course, but Hawking controls the delivery of the talk phrase by phrase - pausing for emphasis, applause or laughter.
• If you ask a question, the response can take a while. Sometimes a short "Yes" will do the trick, but other times you just have to be patient. He has to build up his reply, word by word, then activate his computerized voice to deliver the answer. When one questioner asked Hawking to expound on the possibility that time may be curved in more than one dimension, Hawking took about five minutes to craft two short sentences: "General relativity allows [time] to loop back on itself. However, quantum theory seems to prevent travel into the past."
• Instead of autographing books, Hawking thumbprints them, with the aid of an assistant and an ink pad. A thumbprint also serves as his signature for letters.
• Even though Hawking is almost completely paralyzed, there is lots of expressiveness in his eyes and mouth. X Prize founder Peter Diamandis remarked last week about Hawking's smile - and he's right, it's wonderful. He even has a goofy, paternal grin that showed up during Monday's reception when his toddling grandson scampered around his wheelchair. (Yes, Hawking is a proud grandpa, and he's been visiting family during his U.S. tour).
• If you want to see him smile, just mention his upcoming zero-gravity flight, which serves as a practice run for the outer-space trip Hawking is hoping to take someday aboard Virgin Galactic's SpaceShipTwo. During the warmup to Monday's talk, video from SpaceShipOne's prize-winning flight was shown on the auditorium's big screen - and SpaceShipOne was shown as one of the historical milestones during the talk itself. Is Hawking looking forward to going into weightlessness? One of those smiles was the only answer I needed.

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As physicist Stephen Hawking tours America in advance of his April 26 date with weightlessness, he's clearly hyped up about the trip, says Zero Gravity Corp. founder Peter Diamandis, who saw the great man up close and personal at the California Institute of Technology last week. "He is so excited about the flight," Diamandis told me. "It was wonderful to see him smile."

A lot of other folks are excited about Hawking in return: He's just been voted Britain's second most admired man, according to Esquire magazine. (No. 1 was celebrity chef Gordon Ramsay.) And bidders have paid as much as $75,100 to have two seats on the same weightless flight that Hawking will take.

The $75,000-plus raised for the Starlight Starbright Children's Foundation was just one of the packages that went for charity. Other two-seat packages were provided to the X Prize Foundation, Augie's Quest and Easter Seals, drawing additional tens of thousands of dollars in donations.

Hawking's trip is just one of the developments that have put Zero Gravity Corp. in the news. The company is also offering weightless airline trips in Las Vegas starting this month, and flights will be sold through Sharper Image (through stores, mail-order catalogs and online) beginning May 15.

Meanwhile, the physicist is continuing to combine business and pleasure during his U.S. tour: Over the past month, he's spoken to overflow crowds at the University of California at Berkeley as well as Caltech, and tonight he's speaking at Seattle Center's McCaw Hall. I'll put together a report on the Seattle lecture, "The History of the Universe Backwards" - but in case you missed getting your own ticket, you can watch an hourlong video of the Berkeley talk or read the text transcript.

While I'm on the subject, here's some very important feedback from my earlier article on Stephen Hawking's weightless ride:

Deanna Holt, Springfield, Ill.: "Thank you for your online article regarding Stephen Hawking.  As a special education teacher, I wanted to offer you some words of advice.  In future, you may consider using different words for captions.  Regarding the following:

"'Cambridge physicist Stephen Hawking suffers from a degenerative nerve disease that has turned him into a quadriplegic. He is able to speak only via a computerized voice synthesizer that he operates by batting his eyelids.'

"A better choice would have been the following:

"'Cambridge physicist Stephen Hawking has a degenerative nerve disease that has made him a quadriplegic. He is able to speak via a computerized voice synthesizer that he operates by batting his eyelids.'

"I see a lot of this in the media - you're not the only writer who uses language like this.  Remember, folks with disabilities are folks first.  If they utilize a machine that can enable them to speak - isn't that wonderful?  Being able to speak is a great thing - no matter how it is done.  As far as the suffering ... Mr. Hawking is a 65-year-old, world-famous physicist.  Doesn't sound like he's suffering at all to me.

"Other than that - pretty good article."

Another correspondent said I should have been more specific about Hawking's medical condition:

Jennifer McIntosh: "Thank you for your article on Stephen Hawking's adventure in to weightlessness.  However, something you lacked mentioning in your article disturbed me.  Why do you choose to call Mr. Hawking's condition a  'degenerative nerve disease' and that he is a 'quadriplegic'?  Mr. Hawking is one of few inspirations for people living with ALS.   As a man of science, I would think you would be more specific about such an important detail."

Here's another e-mail in the same vein:

Christopher Martin: "While I found your article on Professor Hawking to be inspiring, I must say that I am pretty upset at that fact you never even mentioned the name of the disease from which he suffers.
 
"In case you were somehow unaware, Stephen Hawking has ALS. Yet, in your article, you refer to his condition as a 'degenerative nerve disease.' While ALS is certainly a neuro-muscular disease marked by 'nerve degeneration,' you seem to pass over the fact that this is the worst neuro-muscular disease you could ever have. 
 
"'Degenerative nerve disease' sounds so innocuous and sounds like something that might be treatable. ALS is not a treatable disease. It is a fatal disease, and any 'treatments' are based on hypotheses rather than detailed medical knowledge of the condition.

"ALS is an orphan disease. It has very little financial, pharmaceutical or medical sponsorship for finding a cure. All knowledge about, and work toward, a cure for ALS stem directly from people around the country spreading the word and raising awareness of this horrible disease.

"That is why I honor my father's memory, and the memory of thousands of others, by working as the chairman of the Greater Philadelphia ALS Association Walk to D'Feet ALS. We walk to defeat this fatal disease, just like the Avon people and Susan Komen people walk to defeat breast cancer.

"All we ask from anyone is the same consideration and acknowledgment for our cause that the rest of the charities out there today receive.

"Thank you for your article on Professor Hawking and have a good day."

For what it's worth, I've revised the original article in accordance with the suggestions.

Billionaire Robert Bigelow is due to detail the business plan behind his orbital space venture at the National Space Symposium on Tuesday, and over the weekend Aviation Week & Space Technology published a preview. Bigelow outlined a timetable that called for three private-sector space stations to be available in orbit for tenants by 2015. But that's not the only big plan that's being previewed on the Internet. Click on the links to learn more about Bigelow Aerospace's vision as well as the SpaceShipOne patent, NASA's CosmosCode scheme and a sky show worth making your own plans for:

• Aviation Week: Bigelow reveals business plan
• SpaceRef: SpaceShipOne patented | Rand's reaction 
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"Who do the people say I am?" The question posed by Jesus in Luke's gospel always gets a thorough airing this time of year. And during this Easter season, there are a few new answers to the historical questions about Christianity's founder. The most ballyhooed controversy focuses on the so-called "Jesus Family Tomb" - the freshly publicized claim that a burial place in suburban Jerusalem could have contained the bones of Jesus' kin, perhaps including his wife. (Mary Magdalene, of course - don't you know your "Da Vinci Code"?)

A good many Christians are thoroughly sick of hearing far-out hypotheses about the historical roots of their religion. But even if you're a true believer, there's still some good that could come out of all the books, magazines and TV shows: You don't have to accept the pop-culture premise to learn a lot about the culture that shaped Christianity.

Take the continuing flap over the Jesus Family Tomb: One of the best-known academic backers of the two-tomb theory, James Tabor of the University of North Carolina at Charlotte, is still fighting the good fight on his "Jesus Dynasty" Web log - even during Holy Week!

In postings to the blog as well to the Society of Biblical Literature's online forum, Tabor ticks off the reasons why Jesus could have been laid to rest first within the tomb mentioned in the gospels, then later moved to another tomb that was perhaps set aside for the great teacher by his disciples.

I can't say I'm persuaded by the statistical analysis of how frequent various biblical-era names are. For a more orthodox perspective on what happened to Jesus' tomb, you're better served by my archived account about the claims made for the Church of the Holy Sepulcher. Nevertheless, if you read Tabor's views as well as the counterarguments from Jodi Magness, his colleague at the University of North Carolina at Chapel Hill, you get some fascinating insights into how the rich and poor of 1st-century Jerusalem lived and died - all the way down to the details of rock-cut tombs, bone boxes and trench graves.

There's still more to glean from a Weblog called "Fact or Fiction? The Tomb of Jesus." The principal mission of this blog is to trash "The Lost Tomb of Jesus" and sell another book, titled "The Jesus Tomb: Is It Fact or Fiction." But you also get a look at the inner workings of the biblical scholarship trade (sometimes it's not a pretty picture) as well as tutorials on arcane subjects such as the symbology of Jewish funerary markings. Did you know that 1st-century bone boxes were marked with scratched X's - not to signify Christian faith, but to indicate which way to slide the lid?

Another example is "The Jesus Mystery," a new volume of scripture-based speculation written by Swedish documentary filmmaker Lena Einhorn. The book compares biblical accounts of Jesus and the apostles with Josephus' contemporary histories - and concludes not only that the time lines of the two tales had been scrambled up, but also that Jesus and the Apostle Paul may well have been the same person.

Again, I'm not convinced by the evidence for Einhorn's conclusions, but I'm interested in the history gleaned along the way: the archaeological traces of the high priest Caiaphas, for instance, or how the church fathers viewed the historical Jesus. One passage, citing Irenaeus' "Against Heresies" from the 2nd century, asserts that Jesus actually lived to be more than 50 years old.

It turns out that there's quite a debate over what Irenaeus really meant - which illustrates another point about unorthodox views of biblical history: Don't take everything you read at face value. (By the way, true skeptics would probably say the same thing about the orthodox view.) Scriptural speculation should eventually lead you to the firmer ground of 1st-century history, and such works as "Daily Life in the Time of Jesus" or "The Greco-Roman World of the New Testament Era."

If your tastes run toward a more transcendental discussion of faith and skepticism, you might want to check out "Is God Real?" - a package from Newsweek that includes an overview on the existential question, a debate between believer Rick Warren and skeptic Sam Harris, a column by Rabbi Marc Gellman and an "On Faith" forum with additional expert opinion.

Pop philosopher Deepak Chopra has his own take on the search for the historical Jesus over at The Huffington Post. And if you're just plain bugged by the religious establishment this Easter weekend, you may find kindred spirits over at the "Blog Against Theocracy" Web portal.

With that, here's wishing you a blessed and peaceful weekend - no matter what your religious persuasion (or non-persuasion) may be.

Update for 9:20 p.m. ET April 6: The University of North Carolina's James Tabor called me back toward evening on Good Friday, to say he was heading over to Israel during Easter weekend for a video shoot with a crew from Australia's "60 Minutes" show. Meanwhile, "The Lost Tomb of Jesus" is still working its way around the world, with airings planned in France, Britain and other international markets. The show will likely be back on the Discovery Channel sometime after the Easter season.

Tabor said more revelations may well come from the "Lost Tomb" at Talpiot, as well as another apparently undisturbed tomb in the same area. In his view, the site is eminently worthy of a closer look - and he agreed that even if you don't buy into the religious angle, the discussion has led to a wider appreciation of the science behind scriptural scholarship.

"I am convinced that the Talpiot tomb deserves some attention and shouldn't be debunked," he told me. "On the other hand, back off a little bit: People have learned what ossuaries are. ... People have learned what mitochondrial DNA is." 

Update for 9:35 p.m. ET April 7: Another work focusing on 1st-century history is "Everyday Life in New Testament Times," written by A.C. Bouquet and published back in 1954. Yes, it was written 50 years ago, when the writing style was different. And it's very respectful of the biblical story, so don't expect any "Da Vinci Code" jaw-droppers. The best part is that it's freely available over the Internet, and you can even print out your own copy if you're so inclined. So I'll anoint "Everyday Life in New Testament Times" as this month's selection for the Cosmic Log Used Book Club. The CLUB Club highlights books with cosmic themes that should be available at your local library or used-book shop. Feel free to add your own suggestions for future club selections.

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The blogosphere crashes into the peer-reviewed academic sphere this week with an essay that tells scientists they must "frame" their findings on controversial issues such as climate change and stem cells, or risk being run over by political spin machines. It's a view you often find on science blogs - and indeed, the co-authors of this week's piece are two well-known science bloggers. But this essay appears in Science, America's most prestigious peer-reviewed scientific journal.

The authors of the piece, "Framing Science," are Matthew Nisbet (a professor at the American University who has a blog also titled Framing Science) and Chris Mooney (author of "The Republican War on Science" and The Intersection's blogmaster). For now, the Policy Forum essay is available only to Science's subscribers, but I would argue this is one article that should be put out in the open online: After all, it's designed to spark a wider discussion about how scientists engage themselves with the public, and makes great fodder for a host of Weblogs to chew on.

The basic point is that it's not enough to focus on "just the facts," even in the fact-based realms of science:

"Without misrepresenting scientific information on highly contested issues, scientists must learn to actively 'frame' information to make it relevant to different audiences. Some in the scientific community have been receptive to this message. However, many scientists retain the well-intentioned belief that, if laypeople better understood technical complexities from news coverage, their viewpoints would be more like scientists', and controversy would subside.

"In reality, citizens do not use the news media as scientists assume. Research shows that people are rarely well enough informed or motivated to weigh competing ideas and arguments. Faced with a daily torrent of news, citizens use their value predispositions (such as political or religious beliefs) as perceptual screens, selecting news outlets and Web sites whose outlooks match their own. Such screening reduces the choices of what to pay attention to and accept as valid. ..."

Nisbet and Mooney go on to cite the examples of climate change, evolutionary biology and human embryonic stem cells. In each case, policy advocates frame the scientific issues in a larger context:

• Those who favor limits on greenhouse-gas emissions point to White House political interference or the threat of mass extinctions, while opponents emphasize scientific uncertainties or undue economic burdens.
• The evolution debate is often framed by Darwin's detractors as a matter of defending moral values. The other side, meanwhile, argues that acceptance of evolutionary theory is a must for any researcher working on a medical advance.
• Stem cells present a similar "battle of the frames," with appeals to morality vs. medical progress. As part of the framing process, stem-cell researchers typically no longer refer to what they do as "cloning," but rather as somatic cell nuclear transfer, or SCNT.

Nisbet and Mooney worry that scientists tend to get too caught up in the raw data - and leave the interpretation and framing to the hurly-burly of the political process. They say it's time for scientists to do the framing first - particularly with the 2008 presidential campaign heating up:

"Some readers may consider our proposals too Orwellian, preferring to safely stick to the facts. Yet scientists must realize that facts will be repeatedly misapplied and twisted in direct proportion to their relevance to the political debate and decision-making. In short, as unnatural as it might feel, in many cases, scientists should strategically avoid emphasizing the technical details of science when trying to defend it."

The reactions to the essay are already mounting up in the blogosphere, and you'll find links to a lot of them from Nisbet and Mooney themselves. I turned to Roger Pielke Jr., director of the University of Colorado's Center for Science and Technology Policy Research. He's one of the science-policy bloggers at Prometheus, and has taken issue with Mooney's ideas in the past as a contributor to TPM Cafe.

This time, Pielke doesn't see a whole lot to disagree with.

"The dynamics that they describe about framing are spot on," he told me today. "This is exactly how humans filter information."

He does quibble, however, with the idea that scientists can hold themselves back from framing their research. "The reality is that scientists do this, too. ... We don't have a choice. We're always framing information when we present it," he said. "I actually teach this stuff, so I'm simpatico with the information they're presenting. Facts don't speak for themselves."

For example, scientists can differ on the basic definition of climate change, which "itself is a political exercise," he said. Should the term refer only to changes that result from greenhouse gases, or should it take in all changes in weather patterns, regardless of the cause? "If you pick one definition over another, it has implications for how you think about the problem and what solutions you come up with," Pielke said.

We're likely to see some great examples of framing in the days ahead - not only when the Intergovernmental Panel on Climate Change releases its next report (duh!), but also when the U.S. Senate debates stem-cell legislation next week. One side will be talking about the perils of killing embryos and the promise of adult stem cells, while the other side will emphasize the frozen-embryo surplus and the promise of imminent cures.

The reality is that both sides in the political debates go beyond the scientific facts - which shouldn't be surprising. Nor should it come as a shock that the scientific process is messy. There are almost always enough loose facts dangling out of a theory to give ideologues something to grasp at.

Thus, framing a controversial issue - that is, seeing the larger pattern within the messy data - is almost always done as a matter of course. And it only makes sense to reduce the scientific complexities to their essentials when presenting the issue to the general public. That's what I try to do all the time.

But when it comes to working the raw data, scientists run the risk of framing their issues too tightly: Researchers are traditionally seen as the umpires for scientific strikes and balls. Sure, there's the occasional bad call or outright scandal - but the scientific process eventually corrects the mistake. If scientists are perceived as outright partisans in the political arena, that could work against the integrity of the scientific process as well as the political process. (Can the words "political" and "integrity" be used in the same sentence?)

This doesn't mean scientists should refrain from politics. Heck, even baseball umpires follow their favorite teams when they're off the field. But when it comes to the facts, scientists should call 'em as they see 'em - and not try to "frame their pitches" to fit the politics.

To see how scientist bloggers can cover the bases on a controversial subject, turn to RealClimate. The beauty of the blog is that the authors are willing to address all those loose ends and errant pitches in depth - with a nicely tuned sense of humor as a bonus. Their April Fool's offering serves as a classic example of inside-baseball satire.

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Two unconventional auto races are getting an extra push of publicity this week: The Automotive X Prize has just formally unveiled its draft rules for super-efficient cars at the New York Auto Show, while one of the teams in the DARPA Urban Challenge is taking its robo-car show on the road.

The $2 million Urban Challenge, sponsored by the Pentagon's Defense Advanced Research Projects Agency, is aimed at promoting the development of autonomous vehicles capable of handling city traffic. Such supply vehicles would have obvious applications in tough environments such as Iraq and Afghanistan, and they're slated to represent a significant proportion of the armed forces' vehicle fleet by the year 2015.

The Urban Challenge is a follow-up to DARPA's open-road race, which was won in 2005 by Team Stanford's modified VW Touareg wagon. This time around, the robotic vehicles will have to handle four-way stops, merging traffic and parking places without having a human hand on the wheel.

Stanford's Urban Challenge entry, a tricked-up VW Passat wagon nicknamed Junior, would have to be considered one of the favorites. But another front-runner is Carnegie Mellon University's Boss, which is a Chevy Tahoe SUV with a robotic upgrade. Actually, there are two Bosses - Boss Tan and Boss Black - and the vehicles have been undergoing testing at an Arizona proving ground.

Last week, Carnegie Mellon's Tartan Racing Team started out on a cross-country trip to bring the vehicles back to Pittsburgh for further work - stopping along the way to visit sponsors in Peoria and Detroit. The Boss should be back home in Pittsburgh this weekend.

Other teams that have been taking to the test tracks include Team LUX and Team Scorpion. Eighty-nine teams in all have applied to compete, and they face an April 13 filing deadline to go on to the next phase of the challenge. The race will really heat up in August, when DARPA is due to announce the semifinalists as well as the location for November's 60-mile final event.

The Automotive X Prize will probably just be getting started by that time. Today marked the official release of the draft rules for that competition, aimed at promoting the development of marketable motor vehicles that can get the equivalent of 100 miles per gallon.

As we discussed last week, the rules will undergo a 60-day public comment period before they're made final. But the draft provides the broad outlines for the competition - or should I say "competitions."

There'll be two tracks: a "mainstream" track for four-wheeled vehicles that meet the conventional expectations for four or more passengers, and an "alternative" class for innovative vehicles that push the transportation envelope while accommodating at least two passengers.

There'll also be two races: a qualifying round in early 2009 and the finals in late 2009. The winners will have to meet the 100 MPGe requirement, hold their greenhouse-gas emissions below a cap (no more than 200 grams of CO2 equivalent per mile) - and of course beat the competition on the race track.

Organizers hope that teams will start signing up this summer, with a formal kickoff event late this year. The registration fee is expected to be $5,000.

Among the unanswered questions:

• Who will sponsor the program? Mark Goodstein, executive director for the Automotive X Prize, told me that his team was "in negotiations with a bunch of foundations and multinationals," but that a deal wasn't ready quite yet.
• How big will the prizes be? The draft rules say the purse "will likely be in excess of" the $10 million that was awarded to the SpaceShipOne team in 2004 for the first privately developed manned spaceship. The total purse will be shared by the winners on the two development tracks, with 75 percent going toward the mainstream class. But there's not yet any specific figure.

The answers to such questions will likely determine whether the Automotive X Prize shifts into the fast lane or rattles along the shoulder. Stay tuned for race updates this summer, and feel free to weigh in with your comments once you've reviewed the guidelines.

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NASA / ESA / STScI / AURA

The galaxy NGC 1672 sparkles in a new image from the Hubble Space Telescope.

Using the Hubble Space Telescope, astronomers have produced a sparkling new picture of a spiral galaxy called NGC 1672 - a distant relative of our own Milky Way, only sexier.

When I say "distant," I'm talking in terms of literal distance: NGC 1672 is 60 million light-years away, in the southern constellation Dorado. And when it comes to the galaxy's relationship to our home galaxy, astronomers see some interesting similarities as well as differences.

Like the Milky Way, NGC 1672 has four major spiral arms that are linked to a straight "bar" of stars and dust. NGC 1672 is just a little smaller than the Milky Way, and both galaxies are apparently anchored at their cores by supermassive black holes. All this leads Joe Liske, a German astronomer at the European Southern Observatory, to call NGC 1672 a "sister galaxy" in a video podcast presented by the European Space Agency's Hubble Information Center.

But unlike the relatively mild-mannered Milky Way, NGC 1672's nucleus is thought to be ablaze with activity, although that blaze is muted by veils of dust.

Might our galaxy light up in the same way, or is it finished with its hot-blooded phase? That's one of the big questions - and one of the reasons why astronomers are interested in active galaxies like NGC 1672 (which is technically classified as a Seyfert galaxy).

They're also curious about the distinction between barred and non-barred spiral galaxies. The central galactic bars may help channel gas from the outlying disk into the nucleus, sparking new waves of star formation - but what are the dynamics of that process? Scientists believe that the bars are relatively short-lived, recurring phenomena - but where do they fit in the cycle of galactic evolution? These are more questions waiting to be answered.

There's no question that NGC 1672 is a stunner: In Hubble's image, based on data collected by the Advanced Camera for Surveys in 2005, young hot stars show up as flashes of blue and violet sparkling around the edges of the spiral arms. Stars and galaxies far beyond NGC 1672 take on a reddened hue, due to the galaxy's intervening veils of dust. Foreground stars in the Milky Way pump up the bling as well.

The ESA's main Web site and its Hubble Information Center offer plenty of stills and videos focusing on NGC 1672, including the aforementioned "Hubblecast" video podcast. The Space Telescope Science Institute's Hubblesite provides yet another perspective on today's image release.

To keep up with the latest from Hubble, you can sign up for the institute's "Inbox Astronomy" e-mail bulletins - and to revel in the telescope's past glories, check out our Space Gallery for Hubble's greatest hits. Our latest "Month in Space" collection includes a galaxy portrait that's literally smashing.

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There are plenty of ways to become a virtual traveler in outer space. Second Life may be the simulation flavor of the week, and NASA may be carving out its own space there, but there's a long history of virtual worlds that give you the feel of the final frontier.

In the wake of last week's story about NASA's involvement in virtual worlds, I received several messages offering a second opinion about Second Life, and a sampling is provided below. Some correspondents rightly pointed out that online space simulations go back to an era when games were played with stolen mainframe moments.

Virtual space adventures have come a long way since Lunar Lander. You can't go wrong with Orbiter, a free sim program that's based on the real physics of spaceflight.

Among the more recent entrants in the field is Space Station Sim, which helps you build and populate a virtual space station. One reviewer called it "a rocket-boosted title that won't break the exploration budget," while another said that trying to build an orbital outpost that passed muster resulted in "more frustration than fun." I have the program at home but haven't yet tried it out myself - so I guess it's time to start launching and find out if I have the Right Stuff.

Another recently released program, Lunar Explorer, uses actual NASA data to create a virtual moon. And if it's interplanetary travel you're interested in, the NASA World Wind project virtually offers you the solar system (as well as Earth).

For an encyclopedic rundown of space simulators, check out the compendium at Clark Lindsey's HobbySpace Log.

Here's a sampling of the messages I've received about Second Life:

Don Mitchell: "Virtual reality is a success today, but I don't think Second Life has been an especially dramatic or innovative step.  Articles in The Register suggest that Second Life is greatly exaggerated (see: 'The phony economics of Second Life').  Personally I found it to be unattractive, and like most subscribers, I left after a couple hours and never returned.

"There have been many high-profile but unsuccessful approaches to Virtual
Reality: the VRML standard, head mounted displays, SIMNET, and a variety of failed 3-D social worlds before Second Life.  The true pioneers of Virtual Reality have been the inventors of computer games.

"Text-based multiplayer games (MUDs) showed that large communities could be built online, and that immersion in virtual reality is mostly a function of the user's mind.  Brilliant software developers like John Carmack ('Quake') and Tim Sweeney ('Unreal') developed efficient techniques for displaying complex 3-D worlds on the PC.  And products like Everquest and World of Warcraft were among the first really successful and compelling examples of multiuser 3-D virtual reality.

"Computer games have driven the high-speed computing and graphics technology of the PC and game consoles.  Along with motion-picture special effects, games are the most economically important application of 3D graphics thus far."

One correspondent dwelled on Second Life's dark side, which I admit I steered clear of during my SL sojourn as Boole Allen:

Tyrel (referring to Second Life and NASA): "Seeing those two phrases together bring tears to my eyes. Second Life is an abomination, explicitly showing all that is wrong with the Internet bundled into a package of pornography and sick fetishes. How the multitudes of reporters somehow don't see the sick sides of Second Life and see it worthy of any sort of reporting is beyond me. (If you want to be 'enlightened' to the true sickness of Second Life, visit somethingawful.com's Second Life Safari).

"What also makes me furious is that programs professionally written in lieu of space simulations barely get the gratification they deserve (such as this masterpiece of space flight simulation) ... while these poorly written, memory leak-ridden, crap programs with hardly enough physics actually programmed into the engine to make a ball bounce partially realistically get front-page articles on major Web sites. This shows that true journalistic research seems to be a thing of the past, or the highest bidder gets the front-page advertisement."

Another correspondent, however, saw a lot of things to praise in Second Life, and his reference to human modification reminded me of our series on the future of evolution: 

Maelstrom Baphomet: "...You are so fascinated with what we do with our environments in the virtual world that you haven't seen the most significant frontier; what we do with our bodies. If the avatars on this game are any hint at what is coming when men master genetics, I don't think the world will belong to what we constitute as humanity in about 1000 years. Instead, you will have a highly modified and modular intelligent life form. ...

"I'll show you places (PG) where dragons roam free and life cycles of their generations are determined by the sun. And we're not talking about human sized dragons.. we're talking about avatars 2-5 times the size of the default avatar in SL. They're built around primative objects that would normally be clothing for the body. Example, a hat is a head.

"Daryth Kennedy is the most dominant artist on the sims in question. She's a longtime friend. I came to her the first night I joined SL in 2005, and I wanted to bring one of my characters to life.  I provided her a picture and she helped me modify her other dragons to create a dragon we called the Maelstrom Dragon. It came packed in a nice little egg you can lay on the ground and grab the contents from. Now the eggs just pass you a pre-organized folder with your avatar and extras. The Maelstrom Dragon contributed to the later creation of the storm dragon, and the character is recognized as the grandfather of the species in a creative sense. The storm was redesigned to a far more aesthetic pure 3-D format with a much brawnier appearance. It now exists in three formats. Hatchling, Wyrmling, and Adult officially. Players, such as myself, have modified them to humanoid variants. I actually find it quite relieving to be something other than human when the opportunity presents itself - as that's what I do every day, be human. There's also a lot of gizmos and trinkets that can be collected and assembled through out SL that can lend an air of magic to the dragons, making them all the more fantasy come to life.

"What people fail to understand is that SL is not virtual reality. It is reality existing in a different state. It's still there, it's just comprised of electrons on a spinning disk, versus atoms on a spinning globe such as humanity is. The characters have souls, it's the souls of the players, giving the creatures on that world life and taking upon themselves a form reflective of their creativity. I am a Christian, and interestingly enough I find this a demonstration of a verse from Genesis where God creates man in his own image. But what is the image of God? God is all powerful, he can make himself whatever he pleases to be ... and true to the script, in this Second Life ... man makes himself in his own image, the manipulable one given by God."

For more about Second Life's religious angle, you'll want to check out today's story in USA Today about the virtual holy season. And if you want to weigh in with your own comments - about space simulations, or about good and evil in virtual worlds - feel free.

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