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Stephen Hawking's new Discovery Channel series, "Into the Universe," aired again last night and continues into next week. In it, the famed cosmologist discusses the mathematical probability of aliens, the Big Bang and time travel. Hawking's theories on time travel in particular seem fairly optimistic - although "Back to the Future"-style DeLoreans are conspicuously absent. That will be the topic next week. Taking a cue from the show, here are five semi-practical models of time travel:
Barrel through a wormhole
If time itself is a dimension like length and height and width, then Hawking says the fabric of time contains imperfections we could take advantage of. A smooth billiards ball has microscopic crevices, and so does spacetime. We'd need to find a true "wormhole" and prop it open, and then head on through.
The caveat, of course, is that we'd be facing heavy radiation feedback concerns (a bit like the screeches you hear at rock concerts) and even without that problem, that we would create paradoxes by messing around with historical events in the past. For this reason, Hawking believes travel to the past may well be impossible.
Go near a black hole
It's simple: All we have to do is find a supermassive black hole and get into its orbit without being sucked into it. Hawking says time would slow down for the people in orbit relative to people elsewhere. Now to find a black hole ...
Go really, really fast
Hawking says if we can get close to the speed of light, a "cosmic speed limit" will kick in to prevent going any faster. Approaching roughly 186,000 miles per second, time will slow down for the traveler vs. the observer. When the traveler emerges, they will have jumped into the future. We just have to develop an engine that can go that fast. Don't try this on the Autobahn, folks.
Live on a space station
Turns out Cosmonaut Sergei Avdeyev is said to hold the record for the most time traveled into the future: about 20 milliseconds. His cumulative experience aboard Russian space station Mir gave him an edge over the competition. Hawking discusses in his documentary how orbiting global positioning satellites must have their timekeeping adjusted every so often because of the relative time slowdown.
Become a Retronaut
This one might be a cop-out, but many scientists (including Hawking) argue that time travel to the past is paradoxical and potentially impossible. In lieu of a Wayback machine, we can turn to the work of Chris Wilds, who created a website about his experiments with being a being a Retronaut. That is, a person who travels into the past by exploring perceptions of time. Whether by looking at old pictures juxtaposed with new ones (which we experimented with at CNN iReport a few weeks ago) or hunting anachronisms, Wilds' site hints that time travel may be all in your head.
Posted by: Nicole Saidi -- CNN iReport Senior Associate ProducerFiled under: Astronomy Space television universe
The Big Crunch may sound like a slogan for crackers or potato chips, but it’s actually an astronomical theory with a gloomy twist.
We’ve all heard of the Big Bang, a widely accepted theory that proposes the entire universe began from a single point about 13.7 billion years ago and has been expanding ever since.
But will it expand forever? Or could it stop and reverse that process?
One possible fate of the universe is the Big Crunch, the idea that the cosmos could one day begin contracting and eventually collapse back on itself or return to a single point.
If it ever happens, this anti-Big Bang would take place so far in the future that Earth might even not exist anymore, according to experts writing for Cornell University’s Curious About Astronomy Web site.
But the experts also took a stab at what a contracting universe could look like to an observer billions of years into the future.
“As the present-day observable universe started to get really small, the observer would most likely see some of the things that happened in the early universe happen in reverse. Most notably, the temperature of the universe would eventually get so high that you could no longer have stable atoms, in which case the hypothetical observer wouldn't be able to hold himself together.”
Yikes. But fear not. It turns the expansion of the universe has been accelerating rather than slowing.
Astronomers believe that’s caused by a mysterious dark energy pulling galaxies apart, according to NASA.
“Dark energy is this idea that not only is the universe expanding, dark energy is actually making that expansion happen even faster,” said Marla Geha, as assistant professor of astronomy at Yale University. “The dark energy will actually continue the expansion of the universe forever, so there probably will not be a Big Crunch if we have the numbers right.”
But the continuous expansion would have other consequences. Over tens of billions of years, the galaxies that we see around us would get farther and farther away, making the universe more of a lonely place, Geha said.
Posted by: A. Pawlowski, CNN.comFiled under: Astronomy NASA Space
Attention stargazers: If you don't mind getting up early (or staying up late) and can get to a rural area without a lot of lights, the skies should put on a show Wednesday about 4 a.m. ET.
Last August's Perseid meteor shower as seen over Bulgaria.
That's when the annual Perseid meteor shower should reach its peak over the east coast of North America, according to SpaceWeather.com. The Perseids appear to come from the constellation Perseus but are actually bits of debris from the Swift-Tuttle comet, which has been orbiting the sun for centuries. The Earth passes through these streams of shooting stars every August.
Astronomers expect up to 200 meteors per hour, although many of the fainter fireballs will not be visible due to moonlight. And of course, clouds or bad weather could render them not visible at all.
If you're lucky enough to witness the Perseids and want to share what you saw, astronomers from the United Kingdom are organizing what they claim to be the world's first mass-participation meteor star party.
The Newbury Astronomical Society is leading a global network of stargazers who will post real-time images of the Perseids on - what else? - Twitter (#meteorwatch). Good luck.
Posted by: Brandon Griggs, CNN.com Tech section producerFiled under: Astronomy
Famous for its reddish color, Mars has long fascinated astronomers, ordinary sky gazers and science-fiction writers.
But its strange, tiny moons also deserve plenty of attention, especially since one of them has been suggested as a way for humans to get to the planet itself.
“To reach Mars, we should use comets, asteroids and Mars’s moon Phobos as intermediate destinations. No giant leaps this time. More like a hop, skip and a jump,” Buzz Aldrin, the second man on the moon, wrote recently in an article in Popular Mechanics. Read more about the moon vs. Mars debate
Phobos is one of two Martian moons, with Deimos keeping it company in space.
Just 13 miles across, Phobos orbits so close to Mars that it may be shattered by the Red Planet’s gravitational tidal forces in about 100 million years, according to NASA.
You can see its battered, pockmarked surface in the photo above, taken by the Mars Reconnaissance Orbiter last year. The Stickney Crater, which takes up almost half its diameter, is on the lower right.
Some astronomy Web sites call Phobos potato-shaped and that’s a good way to describe it!
Think Phobos is small? Deimos is even tinier, at about 7.5 miles in diameter. If you were to stand on the surface of Mars, it would look light a bright star, NASA says.
And here’s a bit of mythology to add to your astronomy knowledge. You may know that Mars was named after the Roman god of war. So in keeping with the tone, Phobos (“Fear”) and Deimos (“Terror”) were named after the horses that pulled the chariot of Ares, the Greek god of war and the counterpart to Mars.
Posted by: A. Pawlowski, CNN.comFiled under: Astronomy Mars NASA Space
After a decade of costly construction, the International Space Station is nearing completion. But NASA won't have long to enjoy the achievement.
According to an article from the Washington Post, NASA space station program manager Michael T. Suffredini raised eyebrows when, at a public hearing last month, he declared flatly that NASA plans to de-orbit the station in 2016.
That means the $100 billion research facility, which has been circling Earth since 1998, will ultimately burst into flames as it reenters the Earth's atmosphere and crashes into the Pacific Ocean.
Budget constraints and the lack of a shuttle program, which is set to retire in 2010, may have persuaded NASA to end the space station program.
The Washington Post explains:
The rap on the space station has always been that it was built primarily to give the space shuttle somewhere to go. Now, with the shuttle being retired at the end of 2010, the station is on the spot. U.S. astronauts will be able to reach the station only by getting rides on Russia's Soyuz spacecraft.
There is no official lobbying to extend the mission, but NASA's plans have met with criticism. Sen. Bill Nelson (D-FL) argues, "If we've spent a hundred billion dollars, I don't think we want to shut it down in 2015."
While speaking to a panel charged by the Obama administration with reviewing the entire human spaceflight program, Nelson affirmed, "My opinion is it would be a travesty to de-orbit this thing... If we get rid of this darned thing in 2015, we're going to cede our leadership in human exploration."
What do you feel should be done with the International Space Station? Does the initial $100 billion investment justify extending the program, or should we simply cut our losses and look toward a new future of space exploration?
Posted by: Wes Finley-Price -- CNN.com WebmasterFiled under: Astronomy International Space Station NASA science Space
In researching a story about what it might look like if you were to fall into a black hole, I came across the concept of white holes.
This is not a new idea, but it’s fascinating, so for those of you who have never heard about it, here’s a primer.
Think of a white hole as an “anti-black hole,” according to Cornell University’s Curious About Astronomy Web site. So if black holes are places where matter is sucked in, white holes could be where it spews out, like water through a fire hose.
“Some people say maybe all that material that’s collapsing into this black hole… goes through a worm hole or some theoretical idea and blasts out in some other place in the universe,” said Jeff McClintock, senior astrophysicist, at the Harvard-Smithsonian Center for Astrophysics.
Another way to look at it is through the waterfall analogy. If you think of a black hole as space falling down one side of a ravine, imagine it bouncing off the bottom and climbing back up the other side, said Andrew Hamilton, a professor of astrophysics at the University of Colorado, Boulder.
“But you never see that thing in nature and it doesn’t happen in real black holes,” Hamilton said.
The concept of white holes is totally theoretical and most people don’t give it much credence, McClintock added.
“Thousands of astronomers are just grinding their brains away on black holes,” he said. “You compare that to a white hole, I don’t think you’ll find one astronomer grinding his brain away.”
Posted by: A. Pawlowski, CNN.comFiled under: Astronomy Space
The sixth planet from the sun, Saturn, is perhaps best known for its many rings, which consist of billions of particles of ice and rock. But throughout the next several months, if you look at Saturn with a telescope, you’ll see something strange – the rings seem to be disappearing.
The Hubble Space Telescope took this image of Saturn, seen titled edge-on, in 1995.
That’s because about every 14 to 15 years, the tilt of the planet is such that we on Earth see the rings edge-on. In reality the rings are still there, but they appear nearly invisible from Earth.
The phenomenon, which stumped Galileo in the 1600s, is called a “ring plane crossing.” While the Earth has an equinox every six months, Saturn's are more spaced out - in fact, it orbits the sun once every 29.5 years.
The rings will appear thinner and thinner until September 4, 2009, when they will seem to have vanished. On that day, we will see the sun and Saturn only 11 degrees apart in the sky, says Linda Spilker at NASA, deputy project scientist and co-investigator on the Cassini Mission to Saturn. But beware – Saturn will be in the daytime sky, making it difficult to see so close to the sun.
Unlike a solar eclipse, the Saturn-with-thin-rings phenomenon will be visible from essentially the whole Earth, because it is so far away, Spilker says. But it will be difficult to actually see this around the exact time of the ring plane crossing in September.
The bottom line is that, while the actual ring crossing doesn’t happen until the fall, if you want to see Saturn appear to have thin rings, act fast!
According to the Sky and Telescope star-gazing guide for this week, Saturn’s rings are only 0.8° or 0.9° from edge-on. The planet rises around 10 p.m.
Read more about the ring crossing from NASA.
Posted by: Elizabeth Landau -- CNN.com Writer/ProducerFiled under: Astronomy Saturn
Just before the sun dips below the horizon, sometimes a brilliant green or blue flash appears at the edge of the fiery ball. To see it, you have to be somewhere with an unobstructed view of the sun and a very stable atmosphere.
Image courtesy and copyright Stéphane Guisard, http://www.astrosurf.com/sguisard
The perfect spot is the Cerro Paranal Observatory in Chile, perched on a 2,635-meter (8,645-foot) mountain in the Atacama Desert, where they get an average of 300 cloudless days per year. Check out these images, as well as another solar phenomenon called a "Gegenschein."
The observatory, which is operated by the 13-nation European Organisation for Astronomical Research in the Southern Hemisphere (ESO), is home to the Very Large Telescope (yes, that's the official name), which ESO describes as the world's most advanced optical instrument.
The green and blue flashes happen when Earth's atmosphere acts as a giant prism, refracting certain colors from the setting sun's rays. It's a tradition at Paranal for the staff to gather at sunset every day to watch for the flashes before settling down for a night of astronomical observations, according to the ESO Web site.
But kids, don't try this at home – at least not without proper eye protection. The ESO site emphasizes that looking at the sun with the naked eye is dangerous, and looking at it through a camera, binoculars, or telescope is even worse. "Do not attempt to observe the Sun unless you know what you are doing," the site warns repeatedly.
–Kate King, Writer, cnn.com
Filed under: Astronomy Sun
Are you a gadgethead? Do you spend hours a day online? Or are you just curious about how technology impacts your life? In this digital age, it's increasingly important to be fluent, or at least familiar, with the big tech trends. From gadgets to Google, smartphones to social media, this blog will help keep you informed.