Daily Archives: May 30, 2017

Existence of Naked Singularity Threatens Einsteins General Theory of Relativity

For 100 years since it was published, Einsteins General Theory of Relativity has mostly passed every kind of test thrown at it. Mostly is a keyword here. Because it implies that there are a few scenarios where the theory doesnt hold up. And one such case is the existence of singularities.

A singularity is defined as a point where the force of gravity is too overwhelming that the laws of physics break down. General relativity says that an example of such singularity exists at the center of a black hole. It also predicts that a black hole is surrounded by what is referred to as an event horizon a.k.a. the point of no return because anything that passes through it gets devoured by the black hole, and nothing (not even light) can escape from gravitys super-strong pull.

This necessarily implies that it is virtually impossible to observe a black hole and its event horizon from the outside or anywhere near it because whatever is being used will just get sucked in, right? Theres actually a term for this cosmic censorship conjecture. It simply means that a singularity will always be cloaked from view. This also suggests that outside a black hole, the singularity within will not have any effect, and general relativitys predictions will remain intact. In short, a singularity cant possibly form outside a black hole.

Still, theres a name given should they happen to be real to a singularity that exists outside a black hole: naked singularity. Predictions about the existence of such have been done before, but they are typically based on a five-dimensional universe. Which is like saying that its impossible for a naked singularity to exist, at least in the universe we know.

So does that mean general relativity will remain uncontested? Maybe. Maybe not. Because according to research recently published in the journal Physical Review Letters, its not just possible for a naked singularity to exist in an extraordinary (or maybe fictional?) universe; it can exist in a real universe like ours too.

Based on simulations done by physicists Toby Crisford and Jorge Santos from the University of Cambridge, a four-dimensional universe (three spatial dimensions plus time as the fourth dimension just like ours) can host a naked singularity. If it happens to be saddle-shaped that is.

General relativity does allow for universes of different shapes. And a saddle-shaped one, also called Anti-de Sitter space, is one of those possible shapes.

One of the distinguishing features of a saddle-shaped universe is a point of no return where light doesnt get trapped, but instead gets reflected back. As described by Crisford to Phys.org: Its a bit like having a spacetime in a box. At the boundary, the walls of the box, we have the freedom to specify what the various fields are doing, and we use this freedom to add energy to the system and eventually force the formation of a singularity.

On the other hand, co-author Santos also says that introducing charged particles in their simulation would probably diminish the formation of the naked singularity. If true, it could imply a connection between the cosmic censorship conjecture and the weak gravity conjecture, which says that any consistent theory of quantum gravity must contain sufficiently charged particles. In Anti-de Sitter space, the cosmic censorship conjecture might be saved by the weak gravity conjecture, he explains.

Its not going to be easy to prove the existence of such an extremely curved saddle-shaped universe, though. Nonetheless, just being possible, is already enough to disrupt what we think we know. And that gives scientists so much more to ponder on, which could hopefully lead to more explanations eventually, instead of more questions.

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Existence of 'Naked Singularity' Threatens Einstein's General Theory of Relativity - Wall Street Pit

From time to time, the Singularity Hub editorial team unearths a gem from the archives and wants to share it all over again. It's usually a piece that was popular back then and we think is still relevant now. This is one of those articles. It was originally published June 19, 2016.We hope you enjoy it!

How do intelligent minds learn?

Consider a toddler navigating her day, bombarded by a kaleidoscope of experiences. How does her mind discover whats normal happenstance and begin building a model of the world? How does she recognize unusual events and incorporate them into her worldview? How does she understand new concepts, often from just a single example?

These are the same questions machine learning scientists ask as they inch closer to AI that matches or even beats human performance. Much of AIs recent victories IBM Watson against Ken Jennings, Googles AlphaGo versus Lee Sedol are rooted in network architectures inspired by multi-layered processing in the human brain.

In a review paper, published in Trends in Cognitive Sciences, scientists from Google DeepMind and Stanford University penned a long-overdue update on a prominent theory of how humans and other intelligent animals learn.

In broad strokes, the Complementary Learning Systems (CLS) theory states that the brain relies on two systems that allow it to rapidly soak in new information, while maintaining a structured model of the world thats resilient to noise.

The core principles of CLS have broad relevance in understanding the organization of memory in biological systems, wrote the authors in the paper.

Whats more, the theorys core principles already implemented in recent themes in machine learning will no doubt guide us towards designing agents with artificial intelligence, they wrote.

In 1995, a team of prominent psychologists sought to explain a memory phenomenon: patients with damage to their hippocampus could no longer form new memories but had full access to remote memories and concepts from their past.

Given the discrepancy, the team reasoned that new learning and old knowledge likely relied on two separate learning systems. Empirical evidence soon pointed to the hippocampus as the site of new learning, and the cortex the outermost layer of the brain as the seat of remote memories.

In a landmark paper, they formalized their ideas into the CLS theory.

According to CLS, the cortex is the memory warehouse of the brain. Rather than storing single experiences or fragmented knowledge, it serves as a well-organized scaffold that gradually accumulates general concepts about the world.

This idea, wrote the authors, was inspired by evidence from early AI research.

Experiments with multi-layer neural nets, the precursors to todays powerful deep neural networks, showed that, with training, the artificial learning systems gradually learned to extract structure from the training data by adjusting connection weights the computer equivalent to neural connections in the brain.

Put simply, the layered structure of the networks allows them to gradually distill individual experiences (or examples) into high-level concepts.

Similar to deep neural nets, the cortex is made up of multiple layers of neurons interconnected with each other, with several input and output layers. It readily receives data from other brain regions through input layers and distills them into databases (prior knowledge) to draw upon when needed.

According to the theory, such networks underlie acquired cognitive abilities of all types in domains as diverse as perception, language, semantic knowledge representation and skilled action, wrote the authors.

Perhaps unsurprisingly, the cortex is often touted as the basis of human intelligence.

Yet this system isnt without fault. For one, its painfully slow. Since a single experience is considered a single sample in statistics, the cortex needs to aggregate over years of experience in order to build an accurate model of the world.

Another issue arises after the network matures. Information stored in the cortex is relatively faithful and stable. Its a blessing and a curse. Consider when you need to dramatically change your perception of something after a single traumatic incident. It pays to be able to update your cortical database without having to go through multiple similar events.

But even the update process itself could radically disrupt the existing network. Jamming new knowledge into a multi-layer network, without regard for existing connections, results in intolerable changes to the network. The consequences are so dire that scientists call the phenomenon is catastrophic interference.

Thankfully, we have a second learning system that complements the cortex.

Unlike the slow-learning cortex, the hippocampus concerns itself with breaking news. Not only does it encode a specific event (for example, drinking your morning coffee), it also jots down the context in which the event occurred (you were in your bed checking email while drinking coffee). This lets you easily distinguish between similar events that happened at different times.

The reason that the hippocampus can encode and delineate detailed memories even when theyre remarkably similar is due to its peculiar connection pattern. When information flows into the structure, it activates a different neural activity pattern for each experience in the downstream pathway. Different network pattern; different memory.

In a way, the hippocampus learning system is the antithesis of its cortical counterpart: its fast, very specific and tailored to each individual experience. Yet the two are inextricably linked: new experiences, temporarily stored in the hippocampus, are gradually integrated into the cortical knowledge scaffold so that new learning becomes part of the databank.

But how do connections from one neural network jump to another?

The original CLS theory didnt yet have an answer. In the new paper, the authors synthesized findings from recent experiments and pointed out one way system transfer could work.

Scientists dont yet have all the answers, but the process seems to happen during rest, including sleep. By recording brain activity of sleeping rats that had been trained on a certain task the day before, scientists repeatedly found that their hippocampi produced a type of electrical activity called sharp-wave ripples (SWR) that propagate to the cortex.

When examined closely, the ripples were actually replays of the same neural pattern that the animal had generated during learning, but sped up to a factor of about 20. Picture fast-forwarding through a recording thats essentially what the hippocampus does during downtime. This speeding up process compresses peaks of neural activity into tighter time windows, which in turn boosts plasticity between the hippocampus and the cortex.

In this way, changes in the hippocampal network can correspondingly tweak neural connections in the cortex.

Unlike catastrophic interference, SWR represent a much gentler way to integrate new information into the cortical database.

Replay also has some other perks. You may remember that the cortex requires a lot of training data to build its concepts. Since a single event is often replayed many times during a sleep episode, SWRs offer a deluge of training data to the cortex.

SWR also offers a way for the brain to hack reality in a way that benefits the person. The hippocampus doesnt faithfully replay all recent activation patterns. Instead, it picks rewarding events and selectively replays them to the cortex.

This means that rare but meaningful events might be given privileged status, allowing them to preferentially reshape cortical learning.

These ideasview memory systems as being optimized to the goals of an organism rather than simply mirroring the structure of the environment, explained the authors in the paper.

This reweighting process is particularly important in enriching the memories of biological agents, something important to consider for artificial intelligence, they wrote.

The two-system set-up is natures solution to efficient learning.

By initially storing information about the new experience in the hippocampus, we make it available for immediate use and we also keep it around so that it can be replayed back to the cortex, interleaving it with ongoing experience and stored information from other relevant experiences, says Stanford psychologist and article author Dr. James McClelland in a press interview.

According to DeepMind neuroscientists Dharshan Kumaran and Demis Hassabis, both authors of the paper, CLS has been instrumental in recent breakthroughs in machine learning.

Convolutional neural networks (CNN), for example, are a type of deep network modeled after the slow-learning neocortical system. Similar to its biological muse, CNNs also gradually learn through repeated, interleaved exposure to a large amount of training data. The system has been particularly successful in achieving state-of-the-art performance in challenging object-recognition tasks, including ImageNet.

Other aspects of CLS theory, such as hippocampal replay, has also been successfully implemented in systems such as DeepMinds Deep Q-Network. Last year, the company reported that the system was capable of learning and playing dozens of Atari 2600 games at a level comparable to professional human gamers.

As in the theory, these neural networks exploit a memory buffer akin to the hippocampus that stores recent episodes of gameplay and replays them in interleaved fashion. This greatly amplifies the use of actual gameplay experience and avoids the tendency for a particular local run of experience to dominate learning in the system, explains Kumaran.

Hassabis agrees.

We believe that the updated CLS theory will likely continue to provide a framework for future research, for both neuroscience and the quest for artificial general intelligence, he says.

Image Credit: Shutterstock

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How to Build a Mind? This Theory May Guide Us Toward an Answer - Singularity Hub

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Shane Dingman - TECHNOLOGY REPORTER

Published Sunday, May 28, 2017 3:56PM EDT

Last updated Sunday, May 28, 2017 4:55PM EDT

The futurist tech evangelizers from Singularity University have run into a problem: Too many people want to drink from the well of its elite educational programs.

Singularity preaches that technologies such as artificial intelligence, gene editing and autonomous vehicles are going to upend existing structures at an exponential pace far quicker than previous technological shifts. The Silicon Valley organization, which is part school, part public-benefit corporation, part conference-marketing business, recently announced that 5,000 people had applied for its intense nine-week Global Solutions summer residency program in Mountain View, Calif. Only 80 slots are available.

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Artificial Intelligence Displayed at CES (The Associated Press)

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Classical science fiction tales about Mars have often been about bug-eyed Martians invading Earth for its precious resources. The reality is that within the next two decadeswith the usual caveats about technical and budgetary limitationshumans will be the ones invading the Red Planet.

This year NASA unveiled its latest plan to hopscotch across 140 million miles to the solar systems fourth planet from the sun. The strategy calls for building a lunar station in orbit around the moon to serve as a sort of staging area for deep-space missions to Mars. Dubbed Deep Space Gateway, the manned outpost will be the launching pad for the Deep Space Transport, the agencys version of the USS Enterprise.

By the early 2030s, an astronaut not named Matt Damon may put the first human footprint on a celestial body since 1969. He or she will need some nifty gadgetry to make life possible on a cold, inhospitable world far, far from the nearest Home Depot.

The evidence that there is water on Mars is overwhelming. Surface streaks on the Red Planet that ebb and flow over time have led scientists to conclude that liquid water is indeed present. Last year, NASA announced it had also found a vast reservoir of ice frozen beneath the planets rocky surface.

Still, for the early travelers to Mars, none of these sources of water may be readily available, or they may be energetically too expensive to access. Instead, future astronauts may use a type of water harvester first developed by scientists at the University of California, Berkeley.

The solar-powered device uses a special metal-organic framework (MOF) to pull water out of the air in conditions as low as 20 percent humidity. The research was published last month in the journal Science.

The prototype was able to harvest about three quarts of water from air in 12 hours using two pounds of MOF. MOFs combine metals like magnesium with organic molecules in a tinker-toy arrangement to create rigid, porous structures to store gases and liquids.

If the relative humidity level on Mars is around 20 percent or more, I do not see why this device cant work there, says Omar Yaghi, a co-author on the paper at UC Berkeley who first invented MOFs about 20 years ago, in reply to an email from Singularity Hub.

While the water harvester would be a boon to parched areas on Earth, such a device would also be useful on bone-dry Mars, where despite desert-like conditions, relative humidity at night can reach 80 to 100 percentmore than enough to suck water out of the alien atmosphere.

Yaghis team is already at work on cheaper and more efficient MOFs for water vapor sorption. It is only a matter of time for this technology to be economically competitive with others.This is a significant step towards future water safety and security, as I call it personalized water.

See Yaghi describe how the water harvester works in the video below.

It seems that we can 3D print just about anything these dayseven working ovaries. The ability to manufacture tools and parts will help Mars colonists, who will likely find themselves restricted to just one piece of carry-on luggage.

A team at Northwestern University recently demonstrated the ability to 3D print structures using Martian and lunar dust. Well, not real off-world dust but NASA-approved copies that simulate their size and shape. The researchers, led by Ramille Shah, used what they call a 3D painting process that employs novel inks that her lab has used previously to print things like graphene and carbon nanotubes.

The research was published earlier this year inNature Scientific Reports.

The 3D-painted material, composed of 90 percent dust by weight, is as flexible and tough as rubber, according to a press release from the university. It can be cut, rolled, folded, and otherwise shaped after being 3D painted. Making interlocking bricks like Legos is even possible.

"For places like other planets and moons, where resources are limited, people would need to use what is available on that planet in order to live," says Shah, an assistant professor at Northwestern's McCormick School of Engineering and of surgery in the Feinberg School of Medicine. Our 3D paints really open up the ability to print different functional or structural objects to make habitats beyond Earth.

NASA is developing its own solution for habitats on the Red Planet. Its an igloo.

Technically, the Mars Ice Home is a large, inflatable inner tube-like structure that would incorporate materials extracted from the planet and encased by a shell of ice.

The idea behind the inflatable part of the structure is that it would be lightweight to transport. Why ice? Water is an excellent shielding material against radiation, one of the biggest hazards facing humans on deep-space missions. Prolonged exposure can cause cancer or even acute radiation sickness.

An alternative would be to bury housing, labs and other buildings below the surface, forcing the explorers to live a troglodyte existence. The Mars Ice Home offers better views.

All of the materials weve selected are translucent, so some outside daylight can pass through and make it feel like youre in a home and not a cave, says Kevin Kempton, principal investigator for the Mars Ice Home project at NASAs Langley Research Center, in a press release.

Its unclear if sci-fi blockbuster The Martian did anything to boost potato sales, but researchers are developing sophisticated self-sustaining grow facilities to supply future astronauts with fresh fruits and vegetables.

One effort is a collaboration between NASA, the University of Arizona (UA) and private enterprise. The Bioregenerative Life Support System, or BLSS, is a hydroponic growth chamber that doesnt need soil (or, thankfully, human feces) to produce food.

The closed-loop system starts with water enriched with nutrients. The nutrient-enriched water supports the root system of the plants. The system is mutually beneficial to people and plants, as the former expel carbon dioxide, which is absorbed by the vegetation. The plants, in turn, produce oxygen as part of the photosynthetic process.

We began our first major project in 2004. We designed and had built a food growth chamber at the South Pole [in Antarctica]. Its still down there working right now, says Gene Giacomelli, director of the Controlled Environment Agriculture Center at UA and former principal investigator on the BLSS project.

BLSS was featured at Biosphere 2, a closed ecological system owned and operated by UA for biological research.

Of course, theres quite a bit of work ahead before astronauts start growing red delicious apples on the red planet. NASA and its commercial partners are still developing the next-generation rockets that will do all the heavy lifting for those future missions. Other projects are under way to build the deep-space habitat modules that will carry humans to Mars.

There are still serious obstacles to overcome. For example, there is the problem of radiation. Researchers funded by the European Space Agency recently announced that they produced a device that mimics space radiation to study its threats and to develop solutions to mitigate its effects on people and equipment. A review of aerospace medicine is currently under way as part of the effort to help humans stay fit and healthy in deep space.

And theres the human drama of being far from home. Are people mentally tough enough to survive such a years-long journey? One study using people wintering in Antarctica is attempting to find out.

This year will mark the 60th anniversary of the beginning of the Space Age, when Russia launched the Sputnik satellite. Reaching Mars in less than a century since that historic moment represents a new future for the human raceone that begins with todays technological innovations.

Image Credit: NASA - Diversity in Mawrth Region, Mars

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A Mars Survival Guide: Finding Food, Water, and Shelter on the Red ... - Singularity Hub