 |
At the center of spiral galaxy M81 is a supermassive black hole about 70 million times more massive than our sun. |
Excerpt from insidescience.org
A physicist presents a solution to present-day cosmic mysteries.
By:
Nikodem Poplawski, Inside Science Minds Guest Columnist
(ISM) -- Our universe may exist inside a black hole. This may sound strange, but it could actually be the best explanation of how the universe began, and what we observe today. It's a theory that has been explored over the past few decades by a small group of physicists including myself.
Successful as it is, there are notable unsolved questions with the standard big bang theory, which suggests that the universe began as a seemingly impossible "singularity," an infinitely small point containing an infinitely high concentration of matter, expanding in size to what we observe today. The theory of inflation, a super-fast expansion of space proposed in recent decades, fills in many important details, such as why slight lumps in the concentration of matter in the early universe coalesced into large celestial bodies such as galaxies and clusters of galaxies.
But these theories leave major questions unresolved. For example: What started the big bang? What caused inflation to end? What is the source of the mysterious dark energy that is apparently causing the universe to speed up its expansion?
The idea that our universe is entirely contained within a black hole provides answers to these problems and many more. It eliminates the notion of physically impossible singularities in our universe. And it draws upon two central theories in physics.
 |
| In this picture, spins in particles interact with spacetime and endow it with a property called "torsion." To understand torsion, imagine spacetime not as a two-dimensional canvas, but as a flexible, one-dimensional rod. Bending the rod corresponds to curving spacetime, and twisting the rod corresponds to spacetime torsion. If a rod is thin, you can bend it, but it's hard to see if it's twisted or not. |
The first is general relativity, the modern theory of gravity. It describes the universe at the largest scales. Any event in the universe occurs as a point in space and time, or spacetime. A massive object such as the Sun distorts or "curves" spacetime, like a bowling ball sitting on a canvas. The Sun's gravitational dent alters the motion of Earth and the other planets orbiting it. The sun's pull of the planets appears to us as the force of gravity.
The second is quantum mechanics, which describes the universe at the smallest scales, such as the level of the atom. However, quantum mechanics and general relativity are currently separate theories; physicists have been striving to combine the two successfully into a single theory of "quantum gravity" to adequately describe important phenomena, including the behavior of subatomic particles in black holes.
A 1960s adaptation of general relativity, called the Einstein-Cartan-Sciama-Kibble theory of gravity, takes into account effects from quantum mechanics. It not only provides a step towards quantum gravity but also leads to an alternative picture of the universe. This variation of general relativity incorporates an important quantum property known as spin. Particles such as atoms and electrons possess spin, or the internal angular momentum that is analogous to a skater spinning on ice.
Spacetime torsion would only be significant, let alone noticeable, in the early universe or in black holes. In these extreme environments, spacetime torsion would manifest itself as a repulsive force that counters the attractive gravitational force coming from spacetime curvature. As in the standard version of general relativity, very massive stars end up collapsing into black holes: regions of space from which nothing, not even light, can escape.
Here is how torsion would play out in the beginning moments of our universe. Initially, the gravitational attraction from curved space would overcome torsion's repulsive forces, serving to collapse matter into smaller regions of space. But eventually torsion would become very strong and prevent matter from compressing into a point of infinite density; matter would reach a state of extremely large but finite density. As energy can be converted into mass, the immensely high gravitational energy in this extremely dense state would cause an intense production of particles, greatly increasing the mass inside the black hole.
The increasing numbers of particles with spin would result in higher levels of spacetime torsion. The repulsive torsion would stop the collapse and would create a "big bounce" like a compressed beach ball that snaps outward. The rapid recoil after such a big bounce could be what has led to our expanding universe. The result of this recoil matches observations of the universe's shape, geometry, and distribution of mass.
In turn, the torsion mechanism suggests an astonishing scenario: every black hole would produce a new, baby universe inside. If that is true, then the first matter in our universe came from somewhere else. So our own universe could be the interior of a black hole existing in another universe. Just as we cannot see what is going on inside black holes in the cosmos, any observers in the parent universe could not see what is going on in ours.
The motion of matter through the black hole's boundary, called an "event horizon," would only happen in one direction, providing a direction of time that we perceive as moving forward. The arrow of time in our universe would therefore be inherited, through torsion, from the parent universe.
Torsion could also explain the observed imbalance between matter and antimatter in the universe. Because of torsion, matter would decay into familiar electrons and quarks, and antimatter would decay into "dark matter," a mysterious invisible form of matter that appears to account for a majority of matter in the universe.
Finally, torsion could be the source of "dark energy," a mysterious form of energy that permeates all of space and increases the rate of expansion of the universe. Geometry with torsion naturally produces a "cosmological constant," a sort of added-on outward force which is the simplest way to explain dark energy. Thus, the observed accelerating expansion of the universe may end up being the strongest evidence for torsion.
Torsion therefore provides a theoretical foundation for a scenario in which the interior of every black hole becomes a new universe. It also appears as a remedy to several major problems of current theory of gravity and cosmology. Physicists still need to combine the Einstein-Cartan-Sciama-Kibble theory fully with quantum mechanics into a quantum theory of gravity. While resolving some major questions, it raises new ones of its own. For example, what do we know about the parent universe and the black hole inside which our own universe resides? How many layers of parent universes would we have? How can we test that our universe lives in a black hole?
The last question can potentially be investigated: since all stars and thus black holes rotate, our universe would have inherited the parent black hole’s axis of rotation as a "preferred direction." There is some recently reported evidence from surveys of over 15,000 galaxies that in one hemisphere of the universe more spiral galaxies are "left-handed", or rotating clockwise, while in the other hemisphere more are "right-handed", or rotating counterclockwise. In any case, I believe that including torsion in geometry of spacetime is a right step towards a successful theory of cosmology.
NASA Ames/SETI Institute/JPL-Caltech
The Future of Technology in 2015?
Excerpt from
cnet.com
The year gone by brought us more robots, worries about artificial intelligence, and difficult lessons on space travel. The big question: where's it all taking us?
Every year, we capture a little bit more of the future -- and yet the future insists on staying ever out of reach.
Consider space travel. Humans have been traveling beyond the atmosphere for more than 50 years now -- but aside from a few overnights on the moon four decades ago, we have yet to venture beyond low Earth orbit.
Or robots. They help build our cars and clean our kitchen floors, but no one would mistake a Kuka or a Roomba for the replicants in "Blade Runner." Siri, Cortana and Alexa, meanwhile, are bringing some personality to the gadgets in our pockets and our houses. Still, that's a long way from HAL or that lad David from the movie "A.I. Artificial Intelligence."
Self-driving cars? Still in low gear, and carrying some bureaucratic baggage that prevents them from ditching certain technology of yesteryear, like steering wheels.
And even when these sci-fi things arrive, will we embrace them? A Pew study earlier this year found that Americans are decidedly undecided. Among the poll respondents, 48 percent said they would like to take a ride in a driverless car, but 50 percent would not. And only 3 percent said they would like to own one.
"Despite their general optimism about the long-term impact of technological change," Aaron Smith of the Pew Research Center wrote in the report, "Americans express significant reservations about some of these potentially short-term developments" such as US airspace being opened to personal drones, robot caregivers for the elderly or wearable or implantable computing devices that would feed them information.
Let's take a look at how much of the future we grasped in 2014 and what we could gain in 2015.
Space travel: 'Space flight is hard'
In 2014, earthlings scored an unprecedented achievement in space exploration when the European Space Agency landed a spacecraft on a speeding comet, with the potential to learn more about the origins of life. No, Bruce Willis wasn't aboard. Nobody was. But when the 220-pound Philae lander, carried to its destination by the Rosetta orbiter, touched down on comet 67P/Churyumov-Gerasimenko on November 12, some 300 million miles from Earth, the celebration was well-earned.A shadow quickly fell on the jubilation, however. Philae could not stick its first landing, bouncing into a darker corner of the comet where its solar panels would not receive enough sunlight to charge the lander's batteries. After two days and just a handful of initial readings sent home, it shut down. For good? Backers have allowed for a ray of hope as the comet passes closer to the sun in 2015. "I think within the team there is no doubt that [Philae] will wake up," lead lander scientist Jean-Pierre Bibring said in December. "And the question is OK, in what shape? My suspicion is we'll be in good shape."
The trip for NASA's New Horizons spacecraft has been much longer: 3 billion miles, all the way to Pluto and the edge of the solar system. Almost nine years after it left Earth, New Horizons in early December came out of hibernation to begin its mission: to explore "a new class of planets we've never seen, in a place we've never been before," said project scientist Hal Weaver. In January, it will begin taking photos and readings of Pluto, and by mid-July, when it swoops closest to Pluto, it will have sent back detailed information about the dwarf planet and its moon, en route to even deeper space.
Also in December, NASA made a first test spaceflight of its Orion capsule on a quick morning jaunt out and back, to just over 3,600 miles above Earth (or approximately 15 times higher than the International Space Station). The distance was trivial compared to those those traveled by Rosetta and New Horizons, and crewed missions won't begin till 2021, but the ambitions are great -- in the 2030s, Orion is expected to carry humans to Mars.
In late March 2015, two humans will head to the ISS to take up residence for a full year, in what would be a record sleepover in orbit. "If a mission to Mars is going to take a three-year round trip," said NASA astronaut Scott Kelly, who will be joined in the effort by Russia's Mikhail Kornienko, "we need to know better how our body and our physiology performs over durations longer than what we've previously on the space station investigated, which is six months."
There were more sobering moments, too, in 2014. In October, Virgin Galactic's sleek, experimental SpaceShipTwo, designed to carry deep-pocketed tourists into space, crashed in the Mojave Desert during a test flight, killing one test pilot and injuring the other. Virgin founder Richard Branson had hoped his vessel would make its first commercial flight by the end of this year or in early 2015, and what comes next remains to be seen. Branson, though, expressed optimism: "Space flight is hard -- but worth it," he said in a blog post shortly after the crash, and in a press conference, he vowed "We'll learn from this, and move forward together." Virgin Galactic could begin testing its next spaceship as soon as early 2015.
The crash of SpaceShipTwo came just a few days after the explosion of an Orbital Sciences rocket lofting an unmanned spacecraft with supplies bound for the International Space Station. And in July, Elon Musk's SpaceX had suffered the loss of one of its Falcon 9 rockets during a test flight. Musk intoned, via Twitter, that "rockets are tricky..."
Still, it was on the whole a good year for SpaceX. In May, it unveiled its first manned spacecraft, the Dragon V2, intended for trips to and from the space station, and in September, it won a $2.6 billion contract from NASA to become one of the first private companies (the other being Boeing) to ferry astronauts to the ISS, beginning as early as 2017. Oh, and SpaceX also has plans to launch microsatellites to establish low-cost Internet service around the globe, saying in November to expect an announcement about that in two to three months -- that is, early in 2015.
One more thing to watch for next year: another launch of the super-secret X-37B space place to do whatever it does during its marathon trips into orbit. The third spaceflight of an X-37B -- a robotic vehicle that, at 29 feet in length, looks like a miniature space shuttle -- ended in October after an astonishing 22 months circling the Earth, conducting "on-orbit experiments."
Self-driving cars: Asleep at what wheel?
Spacecraft aren't the only vehicles capable of autonomous travel -- increasingly, cars are, too. Automakers are toiling toward self-driving cars, and Elon Musk -- whose name comes up again and again when we talk about the near horizon for sci-fi tech -- says we're less than a decade away from capturing that aspect of the future. In October, speaking in his guise as founder of Tesla Motors, Musk said: "Like maybe five or six years from now I think we'll be able to achieve true autonomous driving where you could literally get in the car, go to sleep and wake up at your destination." (He also allowed that we should tack on a few years after that before government regulators give that technology their blessing.)Google has long been working on its own robo-cars, and until this year, that meant taking existing models -- a Prius here, a Lexus there -- and buckling on extraneous gear. Then in May, the tech titan took the wraps off a completely new prototype that it had built from scratch. (In December, it showed off the first fully functional prototype.) It looked rather like a cartoon car, but the real news was that there was no steering wheel, gas pedal or brake pedal -- no need for human controls when software and sensors are there to do the work.
Or not so fast. In August, California's Department of Motor Vehicles declared that Google's test vehicles will need those manual controls after all -- for safety's sake. The company agreed to comply with the state's rules, which went into effect in September, when it began testing the cars on private roads in October.
Regardless of who's making your future robo-car, the vehicle is going to have to be not just smart, but actually thoughtful. It's not enough for the car to know how far it is from nearby cars or what the road conditions are. The machine may well have to make no-win decisions, just as human drivers sometimes do in instantaneous, life-and-death emergencies. "The car is calculating a lot of consequences of its actions," Chris Gerdes, an associate professor of mechanical engineering, said at the Web Summit conference in Dublin, Ireland, in November. "Should it hit the person without a helmet? The larger car or the smaller car?"
Robots: Legging it out
So when do the robots finally become our overlords? Probably not in 2015, but there's sure to be more hand-wringing about both the machines and the artificial intelligence that could -- someday -- make them a match for homo sapiens. At the moment, the threat seems more mundane: when do we lose our jobs to a robot?The inquisitive folks at Pew took that very topic to nearly 1,900 experts, including Vint Cerf, vice president at Google; Web guru Tim Bray; Justin Reich of Harvard University's Berkman Center for Internet & Society; and Jonathan Grudin, principal researcher at Microsoft. According to the resulting report, published in August, the group was almost evenly split -- 48 percent thought it likely that, by 2025, robots and digital agents will have displaced significant numbers of blue- and white-collar workers, perhaps even to the point of breakdowns in the social order, while 52 percent "have faith that human ingenuity will create new jobs, industries, and ways to make a living, just as it has been doing since the dawn of the Industrial Revolution."
Still, for all of the startling skills that robots have acquired so far, they're often not all there yet. Here's some of what we saw from the robot world in 2014:
Teamwork: Researchers at the École Polytechnique Fédérale De Lausanne in May showed off their "Roombots," cog-like robotic balls that can join forces to, say, help a table move across a room or change its height.
A sense of balance: We don't know if Boston Dynamics' humanoid Atlas is ready to trim bonsai trees, but it has learned this much from "The Karate Kid" (the original from the 1980s) -- it can stand on cinder blocks and hold its balance in a crane stance while moving its arms up and down.
Catlike jumps: MIT's cheetah-bot gets higher marks for locomotion. Fed a new algorithm, it can run across a lawn and bound like a cat. And quietly, too. "Our robot can be silent and as efficient as animals. The only things you hear are the feet hitting the ground," MIT's Sangbae Kim, a professor of mechanical engineering, told MIT News. "This is kind of a new paradigm where we're controlling force in a highly dynamic situation. Any legged robot should be able to do this in the future."
Sign language: Toshiba's humanoid Aiko Chihira communicated in Japanese sign language at the CEATEC show in October. Her rudimentary skills, limited for the moment to simple messages such as signed greetings, are expected to blossom by 2020 into areas such as speech synthesis and speech recognition.
Dance skills: Robotic pole dancers? Tobit Software brought a pair, controllable by an Android smartphone, to the Cebit trade show in Germany in March. More lifelike was the animatronic sculpture at a gallery in New York that same month -- but what was up with that witch mask?
Emotional ambition: Eventually, we'll all have humanoid companions -- at least, that's always been one school of thought on our robotic future. One early candidate for that honor could be Pepper, from Softbank and Aldebaran Robotics, which say the 4-foot-tall Pepper is the first robot to read emotions. This emo-bot is expected to go on sale in Japan in February.
Ray guns: Ship shape
Damn the photon torpedoes, and full speed ahead. That could be the motto for the US Navy, which in 2014 deployed a prototype laser weapon -- just one -- aboard a vessel in the Persian Gulf. Through some three months of testing, the device "locked on and destroyed the targets we designated with near-instantaneous lethality," Rear Adm. Matthew L. Klunder, chief of naval research, said in a statement. Those targets were rather modest -- small objects mounted aboard a speeding small boat, a diminutive Scan Eagle unmanned aerial vehicle, and so on -- but the point was made: the laser weapon, operated by a controller like those used for video games, held up well, even in adverse conditions.Artificial intelligence: Danger, Will Robinson?
What happens when robots and other smart machines can not only do, but also think? Will they appreciate us for all our quirky human high and low points, and learn to live with us? Or do they take a hard look at a species that's run its course and either turn us into natural resources, "Matrix"-style, or rain down destruction?Musk himself more than once in 2014 invoked the likes of the "Terminator" movies and the "scary outcomes" that make them such thrilling popcorn fare. Except that he sees a potentially scary reality evolving. In an interview with CNBC in June, he spoke of his investment in AI-minded companies like Vicarious and Deep Mind, saying: "I like to just keep an eye on what's going on with artificial intelligence. I think there is potentially a dangerous outcome."
He has put his anxieties into some particularly colorful phrases. In August, for instance, Musk tweeted that AI is "potentially more dangerous than nukes." And in October, he said this at a symposium at MIT: "With artificial intelligence, we are summoning the demon. ... You know all those stories where there's the guy with the pentagram and the holy water and he's like... yeah, he's sure he can control the demon, [but] it doesn't work out."
Musk has a kindred spirit in Stephen Hawking. The physicist allowed in May that AI could be the "biggest event in human history," and not necessarily in a good way. A month later, he was telling John Oliver, on HBO's "Last Week Tonight," that "artificial intelligence could be a real danger in the not too distant future." How so? "It could design improvements to itself and outsmart us all."
But Google's Eric Schmidt, is having none of that pessimism. At a summit on innovation in December, the executive chairman of the far-thinking tech titan -- which in October teamed up with Oxford University to speed up research on artificial intelligence -- said that while our worries may be natural, "they're also misguided."