• Nov. 23, 2005 |
Dark energy deciphered: Over the past seven years or so, scientists have come around to the view that the universe is dominated by something they don't understand — some strange pressure that is causing the universe to expand more and more rapidly.
To account for the effect of this something — which today is known as "dark energy" — theorists revived a concept that Albert Einstein included in his theories even before anyone knew that the universe was expanding, a factor known as the cosmological constant. Einstein later decided to get rid of the cosmological constant, calling it the "biggest blunder" of his career.
This week, preliminary findings from an ambitious survey of supernovas provide fresh evidence that Einstein was on the right track. In fact, the observations show that dark energy behaves just as the cosmological constant would predict, to a precision of plus or minus 10 percent.
What's more, further observations could nail down once and for all whether Einstein's blunder was actually one of his greatest successes — and whether our universe is headed toward a cosmic fizzle or a catastrophic "Big Rip."
"This is all remarkable," said Richard Ellis, an astronomer at the California Institute of Technology who is part of the international team behind the research. "Our humble telescopes are determining the fate of the universe."
The data were developed by picking out the supernovas in a view of the night sky provided by a 340-million-pixel camera called MegaCam, built by the Canada-France-Hawaii Telescope and the French atomic energy agency. Other big telescopes provided additional spectral data about those supernovas.
Supernovas of a particular type can serve as a "standard candle" for measuring how fast a particular galaxy is receding — and by charting the supernovas at different distances, astronomers can trace how the expansion rate of the universe has changed over time.
The Supernova Legacy Survey is only a year and a half into its projected five-year run, but the first batch of findings, published in the journal Astronomy & Astrophysics (PDF file), is tantalizingly close to what Einstein predicted.
You might say, "So Einstein was right again ... didn't we know that already?" But to physicists trying to figure out how the cosmos works, this is a big deal.
"The significance is huge," University of Toronto astrophysicist Ray Carlberg said in a news release. "Our observation is at odds with a number of theoretical ideas about the nature of dark energy that predict that it should change as the universe expands, and as far as we can see, it doesn't."
Ellis cautioned that the concept of a changing dark energy, known as quintessence, couldn't yet be ruled out completely because of the margin of error. "Ten percent is not great, to be honest, but it's a huge step forward," he told me. "We would not feel comfortable until we got to within, say, 3 percent or even 2 percent."
Here are a few other nuggets from my conversation with Ellis:
- Slowdown vs. speed-up: Astronomers have found that the expansion rate of the universe changed more slowly in the early universe than it has in recent times. How does that square with the constancy of a cosmological constant? Gravity played a role, Ellis explained: "If it's Einstein's cosmological constant, the universe started by slowing down, because gravity was dominant." But as galaxies become more distant from each other, the mutual gravitational attraction is reduced, and dark energy becomes ever more dominant.
- "Big Rip" vs. "Big Chill": If Einstein is right, a key value linked to the cosmological constant, called "w," equals -1. If that value turns out to be less than -1, then the universe will eventually rip itself apart. "We're not excluding that at the moment, but we're comfortably close to a universe that doesn't do that dreadful thing," Ellis said. Instead, it looks as if the cosmos will simply keep expanding, faster and faster, in a scenario you could call the Big Chill. "It will get very cold and dark," Ellis said. "It's a very depressing universe."
- What is it, anyway? Is dark energy the manifestation of tiny ripples in space-time? Does it reflect the influence of nearby extradimensional branes? Astronomers still don't have any idea exactly what dark energy is, let alone why the cosmological constant has the value that it does. But determining that it is a constant, and coming up with a more precise value, will narrow down the theoretical possibilities. "The fact that we see a value close to Einstein's value is already eliminating a range of models," Ellis said. "The problem is that there's just so many of them..."
• Nov. 23, 2005 |
Giving thanks: I'll be logging on as little as possible during this ultra-long Thanksgiving weekend, but it's impossible to stay away completely when there's the big SpaceX launch scheduled Friday, plus the possibility of another asteroid landing. I'll be back in the regular routine on Monday.
• Nov. 23, 2005 |
Wonder and whimsy for the holiday weekend:
• Inside Science News Service: Talking turkey and tryptophan•
• The Onion: All programming to be broadcast in ADHDTV
• Nov. 22, 2005 |
Is New Orleans sunk? Almost three months after Hurricane Katrina devastated the Gulf Coast, scientists, engineers and politicians are still debating whether the worst-hit parts of New Orleans should be restored to what they once were, or given up for lost.
The debate made headlines over the weekend, when a report on CBS' "60 Minutes" gave air time to Timothy Kusky, a Saint Louis University geologist who has been saying for weeks that it's time for New Orleanians to move to higher ground. In response, the New Orleans Times Picayune ran a story headlined "Not So Fast, '60 Minutes,'" in which other researchers insisted that Kusky "went overboard."
Can this city be saved? Joe Suhayda, a coastal oceanographer and retired Louisiana State University engineering professor, has the street cred when it comes to answering that question. After all, he predicted a Katrina-scale catastrophe years ago, and in the storm's wake he is serving as an outside adviser to officials dealing with the aftermath. Suhayda lends his expertise to "Storm That Drowned a City," a TV documentary premiering tonight as part of PBS' "Nova" science series.
Suhayda takes the middle ground on the "stay or go" question: New Orleans can be saved, but the city cannot and should not be restored to what it was before Katrina hit.
"This is the type of life-changing event that we're not going to get over," said Suhayda, who lives up river in Baton Rouge. "The way I see it, we're just headed off in another direction. This is unexplored territory."
So what's the best course for a new New Orleans? If Suhayda were in charge, he'd implement a two-pronged strategy to shore up the city. "We have to address the fact that the interior parts of the city have to be re-engineered or reconfigured," he said.
Some areas have virtually no chance of being rebuilt as they were, because they've subsided so far below sea level. In those cases, Suhayda recommends "moving large amounts of sediment from the Mississippi River through pipelines and actually filling in some of these low-lying areas."
The task may sound herculean, but it's been done before. For example, Suhayda pointed out that the lakefront property where the University of New Orleans is now located "was actually the lake bottom at one point." The base for Interstate 10 was built upon sediments that were piped from the river and laid down in marshlands. Sediment deposition can play a part in restoring coastal habitats as well, he said. Such measures could even out New Orleans' "fishbowl" topography behind the city's protective levees.
"Let's not re-create the topographic features that actually exaggerated the flooding," Suhayda said.
Speaking of the levees, Suhayda said the second part of his rebuilding strategy would involve building floodwalls inside the floodwalls. "We have to have redundancy," he explained. "We need interior management of the flooding. The 17th Street Canal breach was allowed to flood almost 75 percent of the city through one single opening."
He acknowledged that it would be a huge challenge to build a comprehensive system of redundant floodwalls — and so he suggested that authorities start by building walls around the city's critical facilities. "Go ahead and put a flood structure around things like the Superdome, put them around hospitals, so that those critical buildings have an extra level of protection," he said.
Suhayda also acknowledged yet another challenge: that of deciding what exactly should be done. "I am not totally optimistic, because there are so many layers of government involved that I see things moving very slowly," he said.
Some experts think the best thing to do would be to abandon the parts of the city that were worst-hit in the storm, while saving high-value areas that were relatively unaffected, such as the French Quarter. Others have proposed grand schemes to fortify the city against future superstorms.
"The biggest thing I see lacking right now, while we debate the 50-year, Category 5 program, is an interim solution," Suhayda said. While politicians dither, business executives and former residents just might decide to set down permanent roots in Houston or other Gulf Coast refuges — subjecting New Orleans to death by a thousand economic cuts.
"At least let's get something on the ground moving," Suhayda said. "The cleanup is just starting. ... I'm concerned that we need to start moving, even if the plans are a little tentative and they have to be changed later."
"Storm That Drowned a City" is just the first half of tonight's PBS double feature on Katrina. The other half, a "Frontline" documentary titled "The Storm," looks at the hurricane season's political aftershocks.
To monitor the impact of the storm, day by day and month by month, check in with our special report on the "Hurricanes' Aftermath." And for an up-close and personal view of the Gulf Coast reconstruction, bursting with multimedia flavor, you can't do better than "Rising From Ruin: Two Towns Rebuild After Katrina."
• Nov. 22, 2005 |
Your daily dose of science on the Web:
• N.Y. Times (reg. req.): This is your brain under hypnosis•
• • BBC: Does spontaneous human combustion exist? (Via Daily Grail)
Of course, Spirit is a bot, not a tot, and this is definitely not your typical birthday. In fact, Sunday's big day actually marked 687 Earth days of operations on the Red Planet — not exactly a nice round number on the Gregorian calendar. But by Martian reckoning, it was exactly a year ago that Spirit landed in Gusev Crater, and that's a cause for celebration at NASA's Jet Propulsion Laboratory.
To mark the occasion, the rover's mission managers at JPL released a batch of pictures showing Spirit roving around the Martian terrain.
Pretty cool, right? But if Spirit is in the photograph, who else was there to take the picture?
The Spirit portraits are actually a case of trick photography, in which the rover's image is inserted digitally into the frame. It may seem like cheating, but NASA says there's a serious purpose behind the trickery. "Because this synthesis provides viewers with a sense of their own 'virtual presence' (as if they were there themselves), such views can be useful to mission teams in planning exploration by enhancing perspective and a sense of scale," today's photo advisory explains.
The digitally altered photos also can serve an aesthetic purpose. It's not clear how much practical benefit the mission teams can derive from the rover silhouette in this sunset snapshot. But it does give you an appreciation for Spirit's lonely odyssey through the Columbia Hills, on the way to a Martian "Promised Land."
Back in 1997, a big part of the appeal of the Mars Pathfinder photos was that they were shot from the lander, showing a plucky little rover wheeling around the rocks and dunes. Because Spirit and Opportunity, its twin on the other side of Mars, are both working solo, you don't get that sense of the rovers in their environment (except for the occasional shadow view). It's like going on a vacation and taking pictures of monuments with no people around.
So even though it's physically impossible, it's nice to see the rover in the picture for a change. Somehow it reinforces the feeling that Spirit and Opportunity are doing just fine after one Martian year, and that they could still be going strong when their two-Earth-year milestone comes up next January. That's an amazing thought, considering that the rovers' warranties ran out after a mere 90 Martian days.
You can keep up with the progress of the 1-year-olds by checking our "Return to the Red Planet" section and NASA's Mars rover site, as well as the "Mission Update" log maintained by principal investigator Steve Squyres.
• Nov. 21, 2005 |
Moonrock memories: Apollo 12 astronaut Dick Gordon didn't get a chance to pick up his own moon rocks during his lunar mission in November 1969. He was the guy who stayed in the command module as it circled above the moon, waiting for his colleagues Pete Conrad and Alan Bean to do their work on the surface and come back up for the ride home.
On Saturday, Gordon finally received his very own moon rock, during a at Seattle's Museum of Flight.
The lunar specimen is one of the perks that goes along with being named an . NASA established the program last year to honor those who have helped the agency "communicate the benefits and excitement of space exploration."
Before the ceremony, Gordon told me that he didn't know exactly where his rock came from, but he was willing to make up a good story to fit the occasion. "If it's not designated from a certain flight, I'm going to make sure it's from Apollo 12," he joked.
Eventually, moonrock awards will go to all the Mercury, Gemini and Apollo astronauts or their surviving family members — as well as to journalist Walter Cronkite, in recognition of his years of space reporting.
The six rocks that have been distributed to date are not sitting on astronauts' mantelpieces. Instead, the program's rules specify that NASA retains ownership of the specimens, and they must be put on display at an institution of each recipient's choice. In Gordon's case, the rock will be shown at the Museum of Flight in Seattle, his native city.
At the age of 76, Gordon said he's enjoying his retirement and is "no longer gainfully employed." But he still keep tabs on space issues, and he admitted that he's "anxious and curious to hear about the Crew Exploration Vehicle" that NASA is considering for future moon missions. He also admitted that he expected America's human spaceflight program to be farther along by now.
"When the Apollo program ended, there wasn't any of us who didn't anticipate that we'd be back to the moon soon afterward," he said. "We hardly scratched the surface."
Gordon said he and his colleagues in the Apollo astronaut corps believe the trips to the moon had a profound impact. Seeing the earth from the moon helped the astronauts — as well as the earthlings watching at home — realize just how precious their little blue planet was.
"A lot of us put it this way," he told me. "When we went to the moon, we discovered the earth."
Although many of the astronomical 3-D resources are online, you can find plenty of printed materials that put those red-blue glasses to use — such as Astronomy magazine's 3-D issue from March 1998 and National Geographic's 3-D-enabled books on the Red Planet: "Discover Mars" and "Mars: Uncovering the Secrets of the Red Planet." National Geographic also included 3-D views and the required eyeglasses in its August 1998 issue, to go with the cover story on the Mars Pathfinder mission.
Here are some additional pointers from Cosmic Log correspondents:
Eddie Bowers: "I’m a complete 3-D geek, so excuse the nitpicking. Just for future reference, the source for anaglyph glasses is American Paper Optics. If you get paper 3-D glasses anyplace else, it’s a good bet that they actually came from American Paper Optics."If someone is interested in higher-quality (non-paper) glasses, then Anachrome glasses are the way to go."Also, anaglyph isn’t really the same technology that was used in the 1950s during the 3-D movie heyday. They used polarized glasses, much like Imax films do today. The only reason anaglyph is ever used is when you can’t project an image with separate lenses for the left and right image. (which covers TV broadcasts and print 3-D)."Also, there is a new DVD set of Harold Lloyd films that includes his personal 3-D photography (stereo photography was big in the 1950s too) in anaglyph. ..."Michael Howard, Midnight Mars Browser, St. Paul, Minn.: "Talking about 3-D anaglyphs from the Mars rovers, Midnight Mars Browser is free software that automatically downloads the latest rover images and creates false-color and anaglyph versions. You can view the images in a slide show or in virtual-reality panorama format. A writeup on it by Emily Lakdawalla of the Planetary Society is here. As far as I know, Midnight Mars Browser is the only piece of software (for home users, anyway) that will let you view every anaglyph from the Mars Exploration Rover missions.
• Nov. 18, 2005 |
3-D delights: NBC is taking one small step for TV technology on Monday by airing a 3-D episode of the spooky series "Medium," in HDTV even. The red-blue glasses required to get the full three-dimensional effect are being distributed in TV Guide as well as through other outlets. (For the record, NBC is a partner in the MSNBC joint venture.)
But once the show is over, what can you do with those geeky cardboard glasses? Quite a bit, actually.
The same technology that gave '50s-era moviegoers headaches is being used by mission managers at NASA's Jet Propulsion Laboratory to add the third dimension to their stereo images of Mars. If you like Red Planet imagery in color, you'll go ga-ga over the rovers' red-blue 3-D versions of Mars landscapes and close-ups.
You can find still more 3-D views from the Mars Global Surveyor orbiter at Malin Space Science System's Web site, including a red-blue look at a piece of the "Face on Mars." Even the Mars Pathfinder mission provided some 3-D treats back in 1997.
Mars isn't the only interplanetary 3-D target. Just do a search on "NASA" and "anaglyph" (the technical name for these two-in-one 3-D views) and you'll find a bunch, including pictures of Comet Wild 2, the Saturnian moon Hyperion, the surface of Enceladus, and lunar samples from the Apollo era. Speaking of Apollo, astronomer Jim Scotti has put together some additional 3-D views of the moon's surface.
Check out this archived log item, and this addendum, for more about red-blue glasses and where to find them. And if you want to sample a 3-D effect that doesn't rely on the funny-looking spectacles, have a look at "Jiggyvision." But don't look too long: It just might induce motion sickness.
• Nov. 18, 2005 |
Second thoughts on Newton: Readers on both sides of the intelligent-design debate drew the connection between the current science/religion split and the two sides of physicist Isaac Newton's career, as outlined in Monday's log item and presented in greater detail during this week's public-TV documentary on "Newton's Dark Secrets." Here's a selection of the e-mail feedback:
Richard D. Trifan, Ringwood, N.J.: "Newton was able to have his beliefs (in God, and in good science) co-exist because even if we believe in a Creator (which I do not) any healthy, self-respecting view of a God should still allow human beings to use their minds to explore and determine how the universe evolved and sustains itself. Forces like gravity, nuclear fusion in stars, and relativity can explain the universe without necessarily explaining the origin of it. Stephen Hawking is also a supporter of calling the 'pre-universe' condition by the name of God, if this allows the believers in our society to apply and accept the proven science to explain all that has occurred since the Big Bang."Likewise, Newton had just this healthy, self-respecting type of view of what a God would expect or want us to do with our lives. Since he saw no conflict with analyzing the evolving of the universe, the galaxies, the stars, planets and life on them, and positing the existence of a God who would presumably have set this entire process in motion at the start, he opened the 'thinking door' for all believers after him — or should I say, he 'should have' opened this doorway in the minds of believers today. Were today’s believers as open-minded as Newton about their beliefs, they could, in a co-existing fashion, encourage the teaching of the evolution of life (and making appropriate analogies to the evolution of a galaxy, and the star systems) without offending or jolting the believers' pre-existing belief in an original Creator of the universe (and the comfort that this belief brings). Newton’s example absolutely can teach the Kansas Board of Education a tremendous amount about thought processes! Pity that they are not listening."Mike Angove, Fairfax, Va.: "I know you don’t want to hear it ... but methodological naturalism is religion. And this religion is how the Eugenie Scotts of the world demand science be done. So yes ... the lesson is, let's not limit our thinking by religious dogma! Agreed!"Rodger Rast, Sacramento, Calif.: "Unfortunately, it is the evolution theorists that are not following good science anymore. They don't like the conclusions that research points to. Intelligent design is clearly indicated by the data. Unfortunately, there are too numerous young-earth creationists who are not scientifically minded and have arcane unsupportable views of a young earth and, often, [a young] universe. The testable creation model by Hugh Ross at Reasons to Believe has it right. Please check it out. I was once an atheist and had never revisited certain long-held beliefs in view of the newer science discoveries — but the only conclusion that fits the data is that a Creator intelligently crafted much of what we see, using natural processes when practical. ..."Gary, Murfreesboro, Tenn.: "I've always felt that the end goal of science was to explain God's creation - not explain God of the equation. ... To find out that Sir Isaac Newton felt the same way is just completely awesome."
• Nov. 18, 2005 |
Weekend field trips on the World Wide Web:
• SpaceRef: NASA provides early look at future spaceship
• The Economist: Egalitarian search engines
• Nov. 17, 2005 |
Lord of the Einstein rings: In one fell swoop, astronomers using the Hubble Space Telescope have added eight new optical "Einstein rings" to our cosmic menagerie.
Einstein rings, which manifest themselves as faint circles of light around giant galaxies, serve as a beautiful illustration of general relativity at work. That's why they're named after the physicist who came up with the theory in the first place.
The rings serve as a special case of "gravitational lensing," in which light from a faraway galaxy is bent around a foreground galaxy, just as a convex lens bends rays of light as they pass through. The result is that the galaxy takes on a distorted, arclike shape, seemingly curling around the foreground galaxy. If the faraway galaxy is lined up just right, the light is bent into a bull's-eye pattern going all the way around the foreground galaxy. That's an Einstein ring.
The first Einstein ring was spotted in radio wavelengths back in 1987, more than 50 years after Albert Einstein predicted that they should be found. For a classic example, plus a graphic that illustrates why the ring looks the way it does, check out this announcement about the discovery of an infrared Einstein ring in 1998. Our "Putting Einstein to the Test" interactive also explains how gravitational lensing works.
Today's announcement from NASA and the Baltimore-based Space Telescope Science Institute lays out eight rings that were identified through a project known as the Sloan Lens Survey. The institute says only three such rings had previously been seen in visible light.
The Sloan Lens Survey team scanned data from 200,000 galaxies, 2 billion to 4 billion light-years from Earth, looking for the telltale spectral signs that one galaxy was right in front of another one. Then the astronomers picked 28 candidates to get a closer look from Hubble's Advanced Camera for Surveys. Nineteen of those galaxies exhibited signs of gravitational lensing, including the eight rings — which makes Hubble the new "lord of the Einstein rings."
The results represent a significant scientific payoff, said Adam Bolton of the Harvard-Smithsonian Center for Astrophysics, one of the team leaders. "We've succeeded in identifying the one out of every 1,000 galaxies that show these signs of gravitational lensing of another galaxy," he said in a news release.
Close study of the rings and arcs helped the team measure the precise mass of the foreground galaxies. By checking galaxies at different distances, which reflect different time periods, they just might be able to shed more light on dark matter — the mysterious stuff that can be detected only by its gravitational interaction.
"Being able to study these and other gravitational lenses as far back in time as several billion years allows us to see directly whether the distribution of invisible and visible mass changes with cosmic time," another leader of the research team, Leon Koopmans of the Kapteyn Astronomical Institute in the Netherlands, said in a NASA news release.
The initial findings of the survey are to appear in the February 2006 issue of the Astrophysical Journal.
• Nov. 17, 2005 |
Scientific smorgasbord on the World Wide Web:
• New Scientist: Gaming fanatics show hallmarks of drug abuse
• Wired: Making the Red Planet green
Looking for older items? Check the . Share your perspective on cosmic subjects with . If you link to this page, you can use or as the address. MSNBC is not responsible for the content of Internet links.