How 50 Cups of Coffee Can Change Your Life

Each time I make a significant change in my life, I have coffee with 50 people to get their views on my plans.

If you’re raising investment for a start-up, changing careers, or moving to a new city, then you owe it to yourself to have coffee with 50 people before making the jump.

Setting the goal of having coffee with 50 people forces you to be clear about your goals. Making the goal public, one person at a time, also makes it much stronger. Having 50 coffees is good because then you have to commit to the specific move that you want to make. You’ll also get input from smart and interesting people.

50 people could change your life

I first came across the idea in the book, What Colour is Your Parachute?. More recently, Mark Suster put a number on it in his article, Why You Need to Take 50 Coffee Meetings. Until then, I’d just aimed for as many coffees as needed until I had gathered enough input to act on. Now I aim for 50 because it simplifies the process, makes the goal concrete, and is large enough to be a stretch target.

Megan Gebhart became a bit of an Internet celeb and travelled the world meeting new people for the 52 Cup Project. She was inspired by a quote from Charlie Jones: “You will be the same person in five years as you are today, except for the people you meet and the books you read.” 

The hidden insight in the 50 coffees idea is that the biggest changes in your life will only happen through the people that you meet and conversations you have. Human beings create and convey meaning through stories and conversations. If you change the conversations that you’re a part of, then your life changes automatically.

Who to get coffee with

This isn’t 50 coffees with complete strangers. The coffees will be mostly with friends and existing acquaintances. You know that favorite former colleague you keep meaning to catch up with? Now is the time.

Mutual introductions are good. Think one degree of separation. Ask your friends, investors, clients, and colleagues if they know anyone interesting you should meet.

Having coffee with a purpose but without an ulterior motive has made me more confident about meeting new people. I still get nervous about asking someone new for coffee, but I’ve met great people and made some real friends.

50 coffees are worth it

I had 50 coffees when I left law for design. I did it again when I moved to London, and most recently when I published a book. The 50 coffees idea has worked so well for me in the past for these reasons:

My best ideas always come up during a heated conversation. My brain seems to be wired up to my mouth--not always a good thing--but it means that I think better when I’ve got a smart conversation partner to debate with. (Caffeine is great fuel for conspiracy.) For any big life change, there are people out there who have already done what I’m thinking of doing. I can get more from their anecdotes than any book, blog, or article.

To get more input, I try to meet people who have very different backgrounds than mine. I'm not talking about generic catch-up coffees and awkward first-time meetings with sales prospects. Instead, I'm looking for a focused debate with an intelligent peer. The best coffee discussions are about an idea you’re both interested in, or where the other person can give you input on something they like discussing.

Make the most of the coffee

The focus on a real project or issue is what makes this coffee different from just catching up. Instead, you’ll be conspiring, debating, and swapping stories. Being specific about what you want to talk about will make the coffee feel much more valuable. Here's what I've learned: 

Be intentional and focused. Keep the coffee under 20 minutes. I usually meet people at their office and use the walk to and from the cafe to get the conversation going. 

Be honest about what you want. Tell the other person upfront that you want their input on a big move.

Don’t ask for anything. Let the conversation be the value. No selling, no pitching, no interviewing. The other person’s time, advice and story is all that you can ask for in a short coffee meeting like this. 

Think ahead. Formulate five to ten questions in your head that would be interesting for the other person to answer and that would help you triangulate your problem.

Take notes. A general chit-chat will be lost in the sands of time. For your 50 coffees, you should be taking notes because it shows you’re there for a reason and it’ll help you find common themes. Bring a small Moleskine notebook.

A small tickle can be good before asking someone to coffee. Stef and Paul from the start-up foundry Makeshift add people to a Twitter list like, “We should meet” or “Would like to chat." You can do simple things like follow the other person on Twitter or favorite their tweets. Don’t overdo it and add the other person on LinkedIn before even meeting them--that's a bit too forward. Still, it's nice to make some sort of connection in advance.

TIP: Don't waste people's time

Having coffee is contrary to a lot of the popular start-up buzz. Many investors and consultants are sick of getting coffees with strangers who waste their time. Rob and Sal from FounderCentric and LeanCamp invented Startup Burger Nights to avoid coffee meetings, and I know of several London investors who use the “just grab me at Silicon Drinkabout” line to dodge coffee. 

These days it's hip to be unavailable, which is fair enough, but your 50 coffees shouldn’t be the type of banal, time-wasting catch-up that people avoid. You should make the experience fun, easy, and productive.

TechStars mentoring coffee

Coffee meetings are easier in a connected context like the start-up ecosystem, but you can meet anyone if you ask politely. My trick is to watch the other person’s drink. When they finish their coffee, the meeting is over. The theory is that if they’re enjoying the discussion, they’ll be too engaged to drink their coffee. We all reach for our glass in a moment of awkward silence or when we’re bored. Their coffee cup is your hourglass.

TIP: Never steal time

If the other person gives people advice for a living (think consultants and creatives), then don’t ask them for advice on your problem. Instead, just absorb their way of approaching it. Ask for war stories of interesting projects. Ask about how they got started. Let them talk about what they’re interested in.

How to get coffee with anyone

There are lots of ways to ask someone for a coffee, but I like to keep it simple:

Pick a good place. Think from their perspective and offer to meet at a high-quality independent cafe close to their office. I’m lucky because my blogging for The Coffee Hunter takes me to cafes all over London. You can use FourSquare to find a good place that’s close to their office.

Make it a good time. Some people like to do quick meetings in the morning to get them fired up. Others prefer a regular morning coffee or quick lunch. The Brits like "stopping for just one" on the way home from work, and that can be a good time to meet people. The most important thing is that it suits them.

Be interesting. Figure out what they are working on or would be interested in discussing. Put that in the first email.

Be direct. Put the invitation in the first line of the email. The preamble stuff is nice, but don’t bury the lede. 

Tip: Travel for coffee

People crave novelty, so ask for coffee with a local when you travel. I’m now in London and would love to have coffee with someone who has just arrived from New Zealand. Likewise, when I was in New Zealand, I would have been happy to hear from someone who had just arrived from London. Even if you're on vacation, you can always put on your nice jeans and T-shirt to ask a local for coffee.

My next 50 coffees

My next move is to get back into consulting with companies in innovation and social media. I’ve loved working with start-ups in London, and will continue to work with the start-up scene through Converge and the Innovation Warehouse. But now it’s time for the next phase of my career. I’ll be reporting back on the coffees that I have along the way.

Earth's wobble 'fixes' dinner for marine organisms

           
         The cyclic wobble of the Earth on its axis controls the production of a nutrient essential to the health of the ocean, according to a new study in the journal Nature. The discovery of factors that control this nutrient, known as "fixed" nitrogen, gives researchers insight into how the ocean regulates its own life-support system, which in turn affects the Earth's climate and the size of marine fisheries.

Researchers from Princeton University and the Swiss Institute of Technology in Zurich (ETH) report that during the past 160,000 years nitrogen fixation rose and fell in a pattern that closely matched the changing orientation of Earth's axis of rotation, or axial precession. Axial precession occurs on a cycle of roughly 26,000 years and arises because the Earth wobbles slightly as it rotates, similar to the wobble of a toy top. Studies from the 1980s revealed that precession leads to a regular upwelling of deep water in the equatorial Atlantic Ocean roughly every 23,000 years. The upwelling in turn brings nitrogen-poor water to the surface where blue-green algae convert nitrogen drawn from the air into a form that is biologically usable.

The finding that nitrogen fixation is determined by precession-driven upwelling appears to indicate that the ocean's fixed nitrogen reservoir is resilient and that the ocean biosphere can recover from even the most dramatic ecological changes, said second author Daniel Sigman, Princeton's Dusenbury Professor of Geological and Geophysical Sciences.

"By studying the response of nitrogen fixation to different environmental changes in the Earth's past, we have found connections that may ensure that the ocean's fixed nitrogen level will always rebound," Sigman said. "This suggests that an ocean over time has a relatively stable nutrient reservoir, and thus stable productivity."

The reconstructed history of North Atlantic nitrogen fixation (black) is partly driven by the cyclic wobble of the Earth's axis of rotation (orange) and its effect on equatorial Atlantic upwelling. Credit: Daniel Sigman, Department of Geosciences

The rise of deep water spurs nitrogen fixation because that water is low in nitrogen but contains an excess of another key nutrient, phosphorus, Sigman said. The phosphorus fuels the fixing of nitrogen carried out by blue-green algae, also known as cyanobacteria.

"The phosphorus-rich, nitrogen-poor water is a boon to cyanobacteria that can fix their own nitrogen," Sigman said. "By growing more rapidly, the nitrogen-fixers 'top up' the fixed nitrogen to the levels needed by other phytoplankton."

Defects in 2D semiconductors could lead to multi-colored light-emitting devices

When scientists remove individual atoms in a semiconductor material, the resulting vacancies become point defects. Contrary to what their name implies, these defects can have beneficial effects on the semiconductor's properties and enable most functionalities of electronic materials. In a new study, researchers have demonstrated that point defects in 2D semiconductors result in an increase in the overall room-temperature photoluminescence intensity. Further, the defects create a new emission peak that could lead to a better understanding of defect physics in 2D semiconductors as well as future applications such as multi-colored light-emitting devices.

The researchers, led by Sefaattin Tongay, Joonki Suh, and J. Wu, at the University of California, Berkeley, the Chinese Academy of Sciences in Beijing, and MIT, have published their paper on the effects of point defects on 2D semiconductors in a recent issue of Nature's Scientific Reports.

"Typically, defects in materials are considered something not wanted," Tongay told Phys.org. "On the contrary, most of the functionalities of the materials are enabled by various imperfections such as defects. In this work, we show that engineering the defects in two-dimensional materials allows us to create another light emission channel and also enhance the light emission.

"This is likely to be a milestone in the field. We scientists did not know how to observe defects by optical methods, and here we have found the first signatures of defects in 2D semiconductors. That's exciting. Apparently, defects are another way to tune/activate the material's properties on-demand."

While the physics of point defects in 3D semiconductors has been widely studied, much less is known about point defects in the more recently developed 2D semiconductors. The low-dimensional electronic systems are highly susceptible to disorder and imperfections. In 2D semiconductors, this propensity is expected to strongly influence electronic and excitonic processes. One such type of newly emerging 2D semiconductor is monolayer transition metal dichalcogenides (TMDs). Because TMDs have direct band gaps, meaning electrons can directly emit photons, they are promising light-emitting materials.

Here, the scientists found that removing chalcogen (sulfur) atoms from a 0.7-nm-thick sample of the TMD MoS2 significantly changes its optical properties. As the number of defects in the material increases, the overall brightness of the light that is emitted by the material increases. This light has a photoluminescence peak at 1.90 eV, which determines its wavelength and color. But the defects also created a new photoluminescence peak at 1.78 eV.

The scientists found that this lower energy peak dominates the photoluminescence spectrum at low temperatures, and becomes weaker as the temperature increases until it completely disappears above 250 K (-23 °C). However, at room temperature, the presence of such defects enhances the light emission. This observation goes against the conventional wisdom in the new field of 2D semiconductors, which has been that optical emission intensity at room temperature is sufficient criteria for assessing the crystal quality of 2D semiconductors; the results here suggest that assessments of crystal quality should involve low-temperature photoluminescence measurements.

The scientists also demonstrated that vacancy defects have similar effects on the optical properties of two other TMDs, MoSe2 and WSe2. These results indicate that the effects of point defects are likely universal in other 2D semiconductors, as well.

The researchers propose that the underlying mechanism of these effects depends on the interaction of the defect sites with nitrogen gas in the air. In vacuum, the defects did not have any effect on the TMDs' optical properties. The scientists explain that N2 molecules in the air may drain free electrons from the material at the defect sites, which results in a greater proportion of free excitons (electrons bound to holes) in the material. Some portion of the free excitons then get trapped and bound by the defect vacancies, forming bound excitons. Eventually, both free and bound excitons recombine radiatively and yield two distinct light emission peaks at 1.90 eV (~650 nm) and 1.78 eV (~700 nm), respectively.

Since researchers can create these defects by irradiation or thermal annealing, the defect density—and the resulting changes in the material's optical properties—can be controlled via defect engineering. This ability could lead to the production of 2D semiconductors with multiple bandgaps, multi-colored light-emission devices, and optical gas sensors, among other applications.

"With a smart design, point-defective 2D semiconductors potentially show better materials performance, which can be realized by uncovering defect physics in 2D systems," Suh said. "That's our team's ultimate goal!"

Did a hyper-black hole spawn the Universe?

It could be time to bid the Big Bang bye-bye. Cosmologists have speculated that the Universe formed from the debris ejected when a four-dimensional star collapsed into a black hole — a scenario that would help to explain why the cosmos seems to be so uniform in all directions.

The standard Big Bang model tells us that the Universe exploded out of an infinitely dense point, or singularity. But nobody knows what would have triggered this outburst: the known laws of physics cannot tell us what happened at that moment.

“For all physicists know, dragons could have come flying out of the singularity,” says Niayesh Afshordi, an astrophysicist at the Perimeter Institute for Theoretical Physics in Waterloo, Canada.

It is also difficult to explain how a violent Big Bang would have left behind a Universe that has an almost completely uniform temperature, because there does not seem to have been enough time since the birth of the cosmos for it to have reached temperature equilibrium.

To most cosmologists, the most plausible explanation for that uniformity is that, soon after the beginning of time, some unknown form of energy made the young Universe inflate at a rate that was faster than the speed of light. That way, a small patch with roughly uniform temperature would have stretched into the vast cosmos we see today. But Afshordi notes that “the Big Bang was so chaotic, it’s not clear there would have been even a small homogenous patch for inflation to start working on”.

On the brane

In a paper posted last week on the arXiv preprint server¹, Afshordi and his colleagues turn their attention to a proposal² made in 2000 by a team including Gia Dvali, a physicist now at the Ludwig Maximilians University in Munich, Germany. In that model, our three-dimensional (3D) Universe is a membrane, or brane, that floats through a ‘bulk universe’ that has four spatial dimensions.

Ashfordi's team realized that if the bulk universe contained its own four-dimensional (4D) stars, some of them could collapse, forming 4D black holes in the same way that massive stars in our Universe do: they explode as supernovae, violently ejecting their outer layers, while their inner layers collapse into a black hole.

In our Universe, a black hole is bounded by a spherical surface called an event horizon. Whereas in ordinary three-dimensional space it takes a two-dimensional object (a surface) to create a boundary inside a black hole, in the bulk universe the event horizon of a 4D black hole would be a 3D object — a shape called a hypersphere. When Afshordi’s team modelled the death of a 4D star, they found that the ejected material would form a 3D brane surrounding that 3D event horizon, and slowly expand.

The authors postulate that the 3D Universe we live in might be just such a brane — and that we detect the brane’s growth as cosmic expansion. “Astronomers measured that expansion and extrapolated back that the Universe must have begun with a Big Bang — but that is just a mirage,” says Afshordi.

Model discrepancy

The model also naturally explains our Universe’s uniformity. Because the 4D bulk universe could have existed for an infinitely long time in the past, there would have been ample opportunity for different parts of the 4D bulk to reach an equilibrium, which our 3D Universe would have inherited.

The picture has some problems, however. Earlier this year, the European Space Agency's Planck space observatory released data that mapped the slight temperature fluctuations in the cosmic microwave background — the relic radiation that carries imprints of the Universe’s early moments. The observed patterns matched predictions made by the standard Big Bang model and inflation, but the black-hole model deviates from Planck's observations by about 4%. Hoping to resolve the discrepancy, Afshordi says that his is now refining its model.

Despite the mismatch, Dvali praises the ingenious way in which the team threw out the Big Bang model. “The singularity is the most fundamental problem in cosmology and they have rewritten history so that we never encountered it,” he says. Whereas the Planck results “prove that inflation is correct”, they leave open the question of how inflation happened, Dvali adds. The study could help to show how inflation is triggered by the motion of the Universe through a higher-dimensional reality, he says.

பள்ளி மாணவ- மாணவிகள் பள்ளிக்கு செல்போன் கொண்டு செல்ல அரசு தடை விதித்து உள்ளது.

பள்ளி மாணவ- மாணவிகள் பள்ளிக்கு செல்போன் கொண்டு செல்ல அரசு தடை விதித்து உள்ளது. 

பள்ளிகளில் பாடம் நடத்தும் போது எஸ்.எம்.எஸ் அனுப்புவது, ஆபாச வீடியோக்கள் பகிர்ந்து கொள்வது, மாணவிகளை காமெரா மூலம் படம் பிடிப்பது, தேர்வில் மொபைல் போன் மூலம் நூதன முறையில் காப்பி அடிப்பது என்று மாணவர்களின் கவனம் சிதறி கல்வியில் கவனம் குறைகிறது.

பத்து வருடங்களுக்கு முன்பு பள்ளிகளுக்கு அருகில் உள்ள பெட்டிக்கடைகளில் ஆபாச புத்தகங்கள் மறைமுகமாக விற்கப்படும். தற்போது ஆபாச வீடியோக்களை மெமரி கார்டு மூலம் பதிந்து கொடுக்கும் தொழில் பெட்டிக்கடை வியாபாரம் ஆகி உள்ளது.

விஞ்ஞான வளர்ச்சி ஆக்கப் பூர்வமாக பயன்படுவதை போன்றே சீர்கேடுகளுக்கும் வித்தாகிறது. அரசின் இந்த முடிவு வரவேற்க தக்க வேண்டியது.

The Feynman Lectures on Physics

Caltech and The Feynman Lectures Website are pleased to present this online edition of The Feynman Lectures on Physics. Now, anyone with internet access and a web browser can enjoy reading a high-quality up-to-date copy of Feynman's legendary lectures. This edition has been designed for ease of reading on devices of any size or shape; text, figures and equations can all be zoomed without degradation.¹

served by Caltech (generally faster)		served by The Feynman Lectures Website
Volume I mainly mechanics, radiation and heat		Volume I mainly mechanics, radiation and heat

For comments or questions about this edition please contact Michael Gottlieb.

 

 

Richard Feynman, Robert Leighton and Matthew Sands, talking with a teaching assistant after the lecture on The Dependence of Amplitudes on Time,  April 29, 1963.

Photograph by Tom Harvey. Copyright © California Institute of Technology.

Contributions from many parties have enabled and benefitted the creation of the HTML edition of The Feynman Lectures on Physics. We wish to thank

• Carver Mead, for his warm encouragement and generous financial support, without which this edition would have been impossible,
• Thomas Kelleher and Basic Books, for their open-mindedness in allowing this edition to be published free of charge,
• Adam Cochran, for tying up the many slippery loose ends that needed to come together in order for this edition to be realized,
• Alan Rice for his steadfast enthusiasm for this project, and for rallying the support of Caltech's Division of Physics Math and Astronomy ,
• Michael Hartl and Evan Dorn, for the excellent job they did converting Volume I of the FLP LaTeX manuscript into HTML.

today news

On this day in 1956, IBM unveiled its 305 RAMAC computer. Like other pre-transistor computers, the IBM 305 RAMAC was bulky. What made it innovative was its use of the first magnetic disk drive, called the Random Access Method of Accounting and Control. The 50, 24-inch disks that made up the RAMAC system could store a total of 5 megabytes' worth of alphanumeric characters

Astrophysics: Fire in the hole!

This excellent story about black hole physics is from April. I think I missed it - which is why I'm posting it now

In March 2012, Joseph Polchinski began to contemplate suicide — at least in mathematical form. A string theorist at the Kavli Institute for Theoretical Physics in Santa Barbara, California, Polchinski was pondering what would happen to an astronaut who dived into a black hole. Obviously, he would die. But how?

According to the then-accepted account, he wouldn’t feel anything special at first, even when his fall took him through the black hole’s event horizon: the invisible boundary beyond which nothing can escape. But eventually — after hours, days or even weeks if the black hole was big enough — he would begin to notice that gravity was tugging at his feet more strongly than at his head. As his plunge carried him inexorably downwards, the difference in forces would quickly increase and rip him apart, before finally crushing his remnants into the black hole’s infinitely dense core.

But Polchinski’s calculations, carried out with two of his students — Ahmed Almheiri and James Sully — and fellow string theorist Donald Marolf at the University of California, Santa Barbara (UCSB), were telling a different story¹. In their account, quantum effects would turn the event horizon into a seething maelstrom of particles. Anyone who fell into it would hit a wall of fire and be burned to a crisp in an instant.

The team’s verdict, published in July 2012, shocked the physics community. Such firewalls would violate a foundational tenet of physics that was first articulated almost a century ago by Albert Einstein, who used it as the basis of general relativity, his theory of gravity. Known as the equivalence principle, it states in part that an observer falling in a gravitational field — even the powerful one inside a black hole — will see exactly the same phenomena as an observer floating in empty space. Without this principle, Einstein’s framework crumbles.

Well aware of the implications of their claim, Polchinski and his co-authors offered an alternative plot ending in which a firewall does not form. But this solution came with a huge price. Physicists would have to sacrifice the other great pillar of their science: quantum mechanics, the theory governing the interactions between subatomic particles.

The result has been a flurry of research papers about firewalls, all struggling to resolve the impasse, none succeeding to everyone’s satisfaction. Steve Giddings, a quantum physicist at the UCSB, describes the situation as “a crisis in the foundations of physics that may need a revolution to resolve”.

With that thought in mind, black-hole experts came together last month at CERN, Europe’s particle-physics laboratory near Geneva, Switzerland, to grapple with the issue face to face. They hoped to reveal the path towards a unified theory of ‘quantum gravity’ that brings all the fundamental forces of nature under one umbrella — a prize that has eluded physicists for decades.

The firewall idea “shakes the foundations of what most of us believed about black holes”, said Raphael Bousso, a string theorist at the University of California, Berkeley, as he opened his talk at the meeting. “It essentially pits quantum mechanics against general relativity, without giving us any clues as to which direction to go next.”

Fiery origins

The roots of the firewall crisis go back to 1974, when physicist Stephen Hawking at the University of Cambridge, UK, showed that quantum effects cause black holes to run a temperature². Left in isolation, the holes will slowly spew out thermal radiation — photons and other particles — and gradually lose mass until they evaporate away entirely.

These particles aren’t the firewall, however; the subtleties of relativity guarantee that an astronaut falling through the event horizon will not notice this radiation. But Hawking’s result was still startling — not least because the equations of general relativity say that black holes can only swallow mass and grow, not evaporate.

Hawking’s argument basically comes down to the observation that in the quantum realm, ‘empty’ space isn’t empty. Down at this sub-sub-microscopic level, it is in constant turmoil, with pairs of particles and their corresponding antiparticles continually popping into existence before rapidly recombining and vanishing. Only in very delicate laboratory experiments does this submicroscopic frenzy have any observable consequences. But when a particle–antiparticle pair appears just outside a black hole’s event horizon, Hawking realized, one member could fall in before the two recombined, leaving the surviving partner to fly outwards as radiation. The doomed particle would balance the positive energy of the outgoing particle by carrying negative energy inwards — something allowed by quantum rules. That negative energy would then get subtracted from the black hole’s mass, causing the hole to shrink.

Hawking’s original analysis has since been refined and extended by many researchers, and his conclusion is now accepted almost universally. But with it came the disturbing realization that black-hole radiation leads to a paradox that challenges quantum theory.

Quantum mechanics says that information cannot be destroyed. In principle, it should be possible to recover everything there is to know about the objects that fell in a black hole by measuring the quantum state of the radiation coming out. But Hawking showed that it was not that simple: the radiation coming out is random. Toss in a kilogram of rock or a kilogram of computer chips and the result will be the same. Watch the black hole even until it dies, and there would still be no way to tell how it was formed or what fell in it.

This problem, dubbed the black-hole information paradox, divided physicists into two camps. Some, like Hawking, argued that the information truly vanishes when the black hole dies. If that contradicted quantum laws, then better laws needed to be found. Others, like John Preskill, a quantum physicist at the California Institute of Technology in Pasadena, stuck by quantum mechanics. “For a time, I did seriously try to build an alternative theory that included information loss,” he says. “But I couldn’t find one that made any sense — nobody could.” The stalemate continued for the next two decades, finding its most famous expression in 1997, when Preskill publicly bet Hawking that information was not being lost, with the winner to receive an encyclopaedia of his choice.

But that same year, the deadlock was broken by a discovery made by Juan Maldacena, a physicist then at Harvard University in Cambridge. Maldacena’s insight built on an earlier proposal that any three-dimensional (3D) region of our Universe can be described by information encoded on its two-dimensional (2D) boundary^3–5, in much the same way that laser light can encode a 3D scene on a 2D hologram. “We used the word ‘hologram’ as a metaphor,” says Leonard Susskind, a string theorist at Stanford University in California, and one of those who came up with the proposal⁴. “But after doing more mathematics, it seemed to make literal sense that the Universe is a projection of information on the boundary.”

What Maldacena came up with was a concrete mathematical formulation⁶ of the hologram idea that made use of ideas from superstring theory, which posits that elementary particles are composed of tiny vibrating loops of energy. His model envisages a 3D universe containing strings and black holes that are governed only by gravity, bounded by a 2D surface on which elementary particles and fields obey ordinary quantum laws without gravity. Hypothetical residents of the 3D space would never see this boundary because it is infinitely far away. But that wouldn’t matter: anything happening in the 3D universe could be described equally well by equations in the 2D universe, and vice versa. “I found that there’s a mathematical dictionary that allows you to go back and forth between the languages of these two worlds,” Maldacena explains.

This meant that even 3D black-hole evaporation could be described in the 2D world, where there is no gravity, where quantum laws reign supreme and where information can never be lost. And if information is preserved there, then it must also be preserved in the 3D world. Somehow, information must be escaping from the black holes.

One for all

A few years later, Marolf showed that every model of quantum gravity will obey the same rules, whether or not it is built from string theory⁷. “It was a combination of Maldacena and Marolf’s work that turned me around,” explains a long-term proponent of information loss, Ted Jacobson, a quantum physicist at the University of Maryland in College Park. In 2004, Hawking publicly admitted that he had been wrong, and gave Preskill a baseball encyclopaedia to make good on their bet.

Such was the strength of Maldacena’s discovery that most physicists believed that the paradox had been settled — even though nobody had yet explained how Hawking radiation smuggles information out of the black hole. “I guess we just all assumed there would be a straightforward answer,” says Polchinski.

There wasn’t. When Polchinski and his team set themselves the task of clearing up that loose end in early 2012, they soon stumbled on yet another paradox — the one that eventually led them to the fatal firewall.

Hawking had shown that the quantum state of any one particle escaping from the black hole is random, so the particle cannot be carrying any useful information. But in the mid-1990s, Susskind and others realized that information could be encoded in the quantum state of the radiation as a whole if the particles could somehow have their states ‘entangled’ — intertwined in such a way that measurements carried out on one will immediately influence its partner, no matter how far apart they are.

But how could that be, wondered the Polchinski’s team? For a particle to be emitted at all, it has to be entangled with the twin that is sacrificed to the black hole. And if Susskind and others were right, it also had to be entangled with all the Hawking radiation emitted before it. Yet a rigorous result of quantum mechanics dubbed ‘the monogamy of entanglement’ says that one quantum system cannot be fully entangled with two independent systems at once.

To escape this paradox, Polchinski and his co-workers realized, one of the entanglement relationships had to be severed. Reluctant to abandon the one required to encode information in the Hawking radiation, they decided to snip the link binding an escaping Hawking particle to its infalling twin. But there was a cost. “It’s a violent process, like breaking the bonds of a molecule, and it releases energy,” says Polchinski. The energy generated by severing lots of twins would be enormous. “The event horizon would literally be a ring of fire that burns anyone falling through,” he says. And that, in turn, violates the equivalence principle and its assertion that free-fall should feel the same as floating in empty space — impossible when the former ends in incineration. So they posted a paper on the preprint server, arXiv, presenting physicists with a stark choice: either accept that firewalls exist and that general relativity breaks down, or accept that information is lost in black holes and quantum mechanics is wrong¹. “For us, firewalls seem like the least crazy option, given that choice,” says Marolf.

The paper rocked the physics community. “It was outrageous to claim that giving up Einstein’s equivalence principle is the best option,” says Jacobson. Bousso agrees, adding: “A firewall simply can’t appear in empty space, any more than a brick wall can suddenly appear in an empty field and smack you in the face.” If Einstein’s theory doesn’t apply at the event horizon, cosmologists would have to question whether it fully applies anywhere.

Polchinski admits that he thought they could have made a silly mistake. So he turned to Susskind, one of the fathers of holography, to find it. “My first reaction was that they were wrong,” says Susskind. He posted a paper stating as much⁸, before quickly retracting it, after further thought. “My second reaction was that they were right, my third was that they were wrong again, my fourth was that they were right,” he laughs. “It’s earned me the nickname, ‘the yo-yo,’ but my reaction is pretty much the same as most physicists’.”

Since then, more than 40 papers have been posted on the topic in arXiv, but as yet, nobody has found a flaw in the team’s logic. “It’s a really beautiful argument proving that there’s something inconsistent in our thinking about black holes,” says Don Page, a collaborator of Hawking’s during the 1970s who is now at the University of Alberta in Edmonton, Canada. A number of inventive solutions have been offered, however.

Real-world implications

One of the most promising resolutions, according to Susskind, has come from Daniel Harlow, a quantum physicist at Princeton University in New Jersey, and Patrick Hayden, a computer scientist at McGill University in Montreal, Canada. They considered whether an astronaut could ever detect the paradox with a real-world measurement. To do so, he or she would first have to decode a significant portion of the outgoing Hawking radiation, then dive into the black hole to examine the infalling particles. The pair’s calculations show that the radiation is so tough to decode that the black hole would evaporate before the astronaut was ready to jump in⁹. “There’s no fundamental law preventing someone from measuring the paradox,” says Harlow. “But in practice, it’s impossible.”

Giddings, however, argues that the firewall paradox requires a radical solution. He has calculated that if the entanglement between the outgoing Hawking radiation and its infalling twin is not broken until the escaping particle has travelled a short distance away from the event horizon, then the energy released would be much less ferocious, and no firewall would be generated¹⁰. This protects the equivalence principle, but requires some quantum laws to be modified. At the CERN meeting, participants were tantalized by the possibility that Giddings’ model could be tested: it predicts that when two black holes merge, they may produce distinctive ripples in space-time that can be detected by gravitational-wave observatories on Earth. 

There is another option that would save the equivalence principle, but it is so controversial that few dare to champion it: maybe Hawking was right all those years ago and information is lost in black holes. Ironically, it is Preskill, the man who bet against Hawking’s claim, who raised this alternative, at a workshop on firewalls at Stanford at the end of last year. “It’s surprising that people are not seriously thinking about this possibility because it doesn’t seem any crazier than firewalls,” he says — although he adds that his instinct is still that information survives.

The reluctance to revisit Hawking’s old argument is a sign of the immense respect that physicists have for Maldacena’s dictionary relating gravity to quantum theory, which seemingly proved that information cannot be lost. “This is the deepest ever insight into gravity because it links it to quantum fields,” says Polchinski, who compares Maldacena’s result — which has now accumulated close to 9,000 citations — to the nineteenth-century discovery that a single theory connects light, electricity and magnetism. “If the firewall argument had been made in the early 1990s, I think it would have been a powerful argument for information loss,” says Bousso. “But now nobody wants to entertain the possibility that Maldacena is wrong.”

Maldacena is flattered that most physicists would back him in a straight-out fight against Einstein, although he believes it won’t come to that. “To completely understand the firewall paradox, we may need to flesh out that dictionary,” he says, “but we won’t need to throw it out.”

The only consensus so far is that this problem will not go away any time soon. During his talk, Polchinski fielded all proposed strategies for mitigating the firewall, carefully highlighting what he sees as their weaknesses. “I’m sorry that no one has gotten rid of the firewall,” he concludes. “But please keep trying.”

Anna University Revaluation Results 2013

Anna University Revaluation Results 2013
http://www.rejinpaul.com/

இன்றைய செய்தி

நீங்கள் விரும்பும் எந்த நிலையையும் உருவாக்கிக்கொள்ளமுடியும் என்ற சுதந்திரத்தை மட்டுமே படைப்பு உங்களுக்கு அளித்துள்ளது. நீங்கள்தான் துன்பத்தை உருவாக்கிக்கொள்கிறீர்கள்.

உலகில் தினமும் 87 கோடி மக்கள் பட்டினியால் அவதி: ஆய்வில் பரபரப்பு தகவல்

மூன்றில் ஒரு பங்கு உணவு வீணாவதால் உலகில் தினமும் 87 கோடி மக்கள் பட்டினியால் அவதிப்படுகின்றனர்.

ஐ.நா.சபையின் உணவு மற்றும் விவசாய நிறுவனம் சார்பில் சர்வதேச அளவில் ஆய்வு நடத்தப்பட்டது. அதில் உலக அளவில் உற்பத்தியாகும் உணவு பொருட்கள் பெருமளவில் வீணாக்கப்படுவது தெரிய வந்தது.

அதாவது ஆண்டொன்றுக்கு 130 கோடி டன் உணவு பொருட்கள் வீணடிக்கப்படுகிறது. இதனால் உலகம் முழுவதும் ஏராளமான மக்கள் பட்டினி கிடக்கின்றனர்.

அதாவது நாள் ஒன்றுக்கு 87 கோடி பேர் உணவு இன்றி பட்டினி கிடப்பது தெரிய வந்துள்ளது. உணவு பொருட்கள் வீணடிக்கப்படுவதன் மூலம் ரூ.55 ஆயிரம் கோடி மதிப்புள்ள உணவு பொருட்கள் வீணாவதாக அறிக்கையில் தெரிவிக்கப்பட்டுள்ளது. இவற்றில் மீன்கள் மற்றும் கடல் உணவு பொருட்கள் அடங்காது.

உலகம் முழுவதும் 28 சதவீதம் நிலங்களில் விவசாயம் மூலம் உணவு பொருட்கள் தயாரிக்கப்படுகின்றன. அவை வளர்ந்த நாடுகளில் பெருமளவில் வாங்கப்பட்டு சாப்பிடாமல் குப்பையில் கொட்டப்படுகின்றன.

இவை தவிர அதிகமாக விளையும் உணவு தானியங்கள், பழங்கள் மற்றும் காய்கறிகளை பாதுகாப்பாக வைக்க குளிர்சாதன சேமிப்பு கிடங்கு வசதிகள் இல்லாததும் ஒரு காரணமாகும்.

ஆசிய மற்றும் ஐரோப்பிய நாடுகளில் இதுபோன்ற காரணங்களால் உணவு பொருள் வீணாகிறது. அதே வேளையில் சீனா மற்றும் அமெரிக்காவில் பயன்படுத்தப்படாமல் உணவு பொருட்கள் வீணடிக்கப்படுவதும் அறிக்கையில் தெரிய வந்துள்ளது.

Irene Joliot-Curie

It's the birthday of Irène Joliot-Curie, who was born in 1897 in Paris. Curie's parents were Marie Skłodowska-Curie and Pierre Curie. Like them, she became a scientist. In 1934 she and her husband Frédéric Joliot-Curie discovered that they could induce stable light elements to become radioactive by bombarding them with alpha-particles. The following year, they were awarded the Nobel chemistry prize for their discovery.

Deep Impact on the Fritz

The up-close comet mission is currently out of control. 

The Deep Impact spacecraft is having problems. On September 3rd mission principal investigator Michael 
A’Hearn (University of Maryland) reported that the team had lost communication with the spacecraft sometime between August 11th and August 14th — it's unclear exactly when, as the team only links up with the craft about once a week. The last communication was August 8th.


The Jet Propulsion Laboratory announced yesterday that the problem appears to be a software glitch that reset Deep Impact’s computers into a constant reboot mode. Without computers to control its thrusters, the craft can’t hold still, and the team doesn’t know its current orientation. That makes reestablishing communication hard: it’s tricky broadcasting to antennas when you don’t know which ones are pointing at you. 

There’s also the problem of power. Deep Impact’s solar cells aim in one direction, and if they’re not facing the Sun, the craft won’t be able to recharge its batteries. A dead craft can’t be communicated with, regardless of orientation. 

Deep Impact is a long-lived interplanetary mission. It jettisoned a projectile that Comet 9P/Tempel 1 “ran over” on Independence Day in 2005, excavating material and allowing scientists to study the comet’s composition. The spacecraft was subsequently recommissioned to a dual mission called EPOXI (short for EPOCH and DIXI, both of which are also acronyms) to investigate comets and exoplanets. In 2010 the craft swept past Comet 103P/Hartley 2, taking fantastic images of the individual jets of gas and dust on the comet’s surface.

Right now the spacecraft was supposed to be observing Comet ISON, which has been the recipient (or victim?) of much fanfare this year. Deep Impact’s pre-perihelion observing window extended from early July to early September, but because of the glitch the team has missed out on about half of that window. 

Spider silk darkened with a coating of carbon nanotubes can tell if your heart just skipped a beat.

Spider silk darkened with a coating of carbon nanotubes can tell if your heart just skipped a beat.

Following a few simple steps, researchers have made a silk-nanotube hybrid that is tough, flexible and electrically conductive. The material might find uses in a range of bendy medical sensors.

Long known as one of nature's toughest and most flexible materials, spider silk is not naturally conductive. Scientists have previously married metals such as gold with spider silk, but those hybrids didn't allow the silk to stretch as much as usual.

To create a conductive but less rigid silk, Eden Steven at Florida State University in Tallahassee collected bundles of silk from a species of golden orb-weaver spider. He polarised a powder of carbon nanotubes so that the tubes would stick to the naturally charged silk, then mixed the materials with a few drops of water and pressed them between two sheets of Teflon.

Wrap, shrink

When the material dried out, the silk was coated with a thin layer of nanotubes. This composite is three times tougher than spider silk alone. As the silk naturally expands and contracts when exposed to different humidity levels, the new, flexible hybrid can be easily manipulated to create good electrical contact for wiring. "We simply wind the coated fibre around the contact area and, by controlling the humidity, we can let it shrink. The wire grips the contact area without having to use a conducting paste or solder."

The carbon-silk combination is also sensitive enough to detect the electrical signals from a heart pulse.

Commercially available pulse-detectors are often made of rigid materials. By contrast, the silk-based version can be wrapped around irregularly shaped objects, such as wrists or fingers, without losing sensitivity.

Kitchen simplicity

"These results open new opportunities in moulding and shaping actuators or sensors, where you could potentially think about different geometries or forms," says bioengineer Kimberly Hamad-Schifferli of the Massachusetts Institute of Technology. There are other methods of combining carbon nanotubes with biological materials, she adds, but they usually require expensive equipment and chemicals, and the end result is not mouldable.

"What's really astonishing is that the method of incorporation of the carbon nanotubes is incredibly simple," she says. "It looks like something you could do in your kitchen at home."

Scaling up production may be a challenge, though, as it is hard to farm spider silk in large amounts. But there has been recent progress making synthetic silk, Steven says, which could pave the way for large-scale production.

காமராசர் முதலமைச்சராக இருந்தபோது நடந்த நிகழ்வு இது

காமராசர் முதலமைச்சராக இருந்தபோது நடந்த நிகழ்வு இது. 

எம்.பி.பி.எஸ். விண்ணப்பதாரர்களுக்கான இடங்களைத் தேர்ந்தெடுத்துவிட்டு காமராசரிடம்,

"உங்களுடைய கோட்டா 20 சீட்கள் மிச்சமிருக்கின்றன'' என்று அதிகாரிகள் கூறினர்.

உடனே விண்ணப்பங்களை வாங்கி மளமளவென்று 20 மாணவர்களைத் தேர்வு செய்து தந்தார் காமராசர்.

எந்த அடிப்படையில் தேர்வு செய்தார் என்பதை அதிகாரிகளால் புரிந்து கொள்ள முடியவில்லை. அவரிடமே அதைக் கேட்டார்கள்.

அதற்கு காமராசர்,

"நான் தேர்வு செய்த மாணவர்களின் பெற்றோர்கள் அனைவருமே எழுதப்படிக்கத் தெரியாதவர்கள். எல்லோரும் விண்ணப்பத்தில் கைநாட்டு போட்டிருக்கிறார்கள். இதைப் பாருங்கள்'' என்று கூறினார்.

அதிகாரிகள் ஆச்சரியப்பட்டு, காமராசரின் சமுதாய அக்கறையை நினைத்துப் பார்த்து வியந்து போனார்கள்.

சீனாவிலும் ஜப்பானிலும் புற்றுநோய் குறைவு - ரகசியம் என்ன?

சீனாவிலும் ஜப்பானிலும் புற்றுநோய் குறைவு - ரகசியம் என்ன?

கிரீன் டீக்கு பச்சைக் கொடி காட்டியவர் சீன நாட்டு மன்னராக இருந்த ஷென் நங் தான். புதிதாகப் பறிக்கப்பட்ட பச்சைத் தேயிலை இலைகளை வெந்நீரில் போட்டு கொதிக்க வைத்தபோது கருஞ்சிவப்பு நிறத்தில் திரவம் வெளிப்பட்டது.

அதைக் குடித்த நங் தாங்கமுடியாத உற்சாகத்தால் குதிக்க ஆரம்பித்துவிட்டார். அந்த ஆட்டத்திலிருந்து தொடங்கியதுதான் கிரீன் டீயின் வரலாறு. சாயா என்ற வார்த்தைக்கும் சொந்தக்காரர்கள் சீனர்கள்தான். சா என்ற சொல்லிலிருந்தே சாயா.

பச்சைத்தேயிலை சாயாவுக்குத் தொடக்கம் சீனாவாக இருந்தாலும், அது எல்லா இடங்களுக்கும் பரவி பச்சைத் தேயிலை உற்பத்தியில் ஒவ்வொரு நாடும் போட்டி போடுகிற நிலைக்குக் கொண்டு போய்விட்டது. இதன் வரிசையில் மலை மாவட்டமான நீலகிரியில் பிரதானத் தொழிலான தேயிலைத் தொழிலில் முதலிடத்தில் இருப்பது பசுந்தேயிலை. அதேபோல, தேயிலை வர்த்தகத்தில் முதலிடத்தில் இருப்பது பச்சைத்தேயிலை.
பசுந்தேயிலை என்பது தேயிலைத்தூள் உற்பத்திக்காக தேயிலைச் செடிகளிலிருந்து பறிக்கப்படும் கொழுந்து. இதைப் பல்வேறு வகைகளில் பதப்படுத்தி தேயிலைத்தூளாகத் தயாரிக்கப்படும். ஆனால், பச்சைத் தேயிலை என்பது தேயிலைச் செடிகளிலிருந்து பறிக்கும் கொழுந்தை அப்படியே உலர வைத்து பின்னர் பயன்படுத்துவது. பச்சைத் தேயிலை அதிக அளவில் உபயோகப்படுத்துவதால் ஏற்படும் பயன் என்ன தெரியுமா?

புற்று நோய்க்கு அருமருந்து : கலிபோர்னியாவிலுள்ள ஜான் வெயின்ஸ் புற்றுநோய் மையத்தில் ஆராய்ச்சிப் பிரிவில் பணியாற்றும் தமிழகத்தைச் சேர்ந்த டி.எஸ்.சரவணன் மேற்கொண்ட கிரீன் டீ குறித்த ஒரு ஆராய்ச்சியில் இது தெரியவந்துள்ளது. “கிரீன் டீயிலுள்ள இஜிசிஜி எனப்படும் (Epi Gallo Catechin Gallate ) பொருள் மிகச்சிறந்த மருத்துவ நிவாரணி என்பதால் புற்றுநோயைக் குணப்படுத்துவதில் இதன் பங்கு பிரதானமானது.”

மார்பகப் புற்று நோய்க்கும், கல்லீரல் புற்றுநோய்க்கும் மிகச்சிறந்த மருந்து பொருளாகவும் கிரீன் டீ பயன்படுகிறது. புற்றுநோய்க்குக் காரணமான செல்களை வளரவிடாமல் தடுப்பதே இதன் முக்கிய வேலை. இந்தப் பச்சைத் தேயிலையை சீனர்களும், ஜப்பானியர்களும் மட்டுமே அதிகளவில் பயன்படுத்தி வருகின்றனர். அதனால் உலகளவில் மற்ற நாட்டினரைவிட புற்றுநோய்க்கு ஆளாவது சீனாவிலும் ஜப்பானிலும் மிகவும் குறைவு.

சீனப் போர்ப்படை வீரர்கள் யுத்தத்திற்குச் செல்வதற்கு முன்னர் கிரீன் டீயைப் பருகிவிட்டுத்தான் போர்க்களத்திற்கே செல்வார்களாம். அந்த அளவிற்கு இது வலிமை மிக்க பொருளாகவும் கருதப்பட்டு வந்தது. கிரீன் டீ பருகுவதால் தோல் விரைவில் சுருக்கமடையாது என்பதோடு, இளமையுடனும், வனப்புடனும் காணப்படுவதற்கு இதுவே முக்கிய காரணமென்பதை சீனர்களின் வாதம். அத்துடன் கிரீன் டீயில் இயற்கையாகவே புளோரைடு எனப்படும் பொருள் அமைந்துள்ளது.

பற்பசைகளில் புளோரைடுக்காக கூடுதல் விலையைக் கொடுத்து வாங்கும் நிலையில் இயற்கையாகவே கிரீன் டீயில் புளோரைடு அமைந்துள்ளதால் இது பற்களுக்கும் பாதுகாப்பானதாகும். உடலில் உணவுப் பொருள் ஜீரணத்திற்கு முக்கியமானதான கிரீன் டீயில் உள்ள டாக்சிஜன்ட் தன்மை, குடலிலுள்ள சிறு துகள்களைக்கூட அகற்றும் வல்லமை கொண்டதாகும் என்கிறார் சரவணன். சீனாவிலிருந்து சென்ற புத்தமதமத் துறவிகளால் ஜப்பானில் அறிமுகப்படுத்தப்பட்ட தேயிலை பின்னர் இங்கிலாந்திற்கும் கொண்டு சென்று பயிரிடப்பட்டது.

அங்கு பகல் உணவின்போது பகல் 12 மணி முதல் பிற்பகல் 3 மணி வரை குடிக்கும் டீயை ஹை டீ எனவும், மற்ற நேரங்களில் களைப்பிற்காகவும், புத்துணர்வுக்காகவும் குடிக்கும் டீயை லோ டீ எனவும் அழைக்கிறார்கள் சுமார் 400 ஆண்டுகளுக்கு முன்னர் 1610ம் ஆண்டுகளில் தேநீர் என்பது பணக்காரர்களின் பானமாகவே கருதப்பட்டது. அப்போது 1 பவுண்டு தேயிலை 100 டாலருக்கு விற்கப்பட்டதாக வரலாறே உள்ளது.

கிரீன் டீ குடிப்பதனால் ஏற்படும் நன்மைகள்



கிரீன் டீயின் ரகசியமே அதில் அதிக அளவில் உள்ள உயர்தர ஆன்டி ஆக்சிடென்ட்கள் தான். இதனை தமிழில் நோய் எதிர்ப்பு சக்தி என்று அழைக்கிறோம்.

பழங்கள், காய்கறிகள், கீரைகளில் உள்ளதை விட பல மடங்கு அதிகமாக சத்து இதில் உள்ளது.

சுருக்கமாக சொன்னால் ஒரு கப் கிரீன் டீ 10 கப் ஆப்பிள் ஜுஸ்க்கு சமம். கிரீன் டியின் உயர்தர ஆன்டி ஆக்சிடென்ட்கள் அபாயகரமான பிரீ ரேடி செல்களை சமன்படுத்தி, நம் உடலில் ஒவ்வொரு செல்லையும் புதுப்பித்து வாழ்நாட்களை நீடிக்க செய்கின்றன.

எனவேதான் சீனர்கள் சராசரியாக 90 வயதை தாண்டி வாழ்வதாக ஆராய்ச்சியாளர்கள் தெரிவித்துள்ளனர்.

கிரீன் டீயின் நன்மைகள்

1. ரத்தத்தில் உள்ள கெட்ட கொலஸ்ட்ராலை குறைக்கிறது.

2. உயர் ரத்த அழுத்தத்தை கட்டுப்படுத்துகிறது.

3. உடலில் உள்ள தேவைக்கு அதிகமான கலோரிகளை வேகமாக எரித்தது தேவையற்ற கொழுப்பை குறைத்தது உடல் எடையை சீராக வைக்க உதவுகிறது.

4. ரத்த குழாயில் அடைப்பு ஏற்படுவதை குறைக்கிறது.

5. இதய நோய் வராமல் தடுக்கிறது.

6. ரத்தத்தில் உள்ள சக்கரை அளவை கட்டுப்படுத்துகிறது.

7. உடலில் உள்ள திரவ அளவை சமன் செய்து சோம்பலை போக்குகிறது.

8. புற்றுநோய் வராமல் தடுக்கிறது.

9. புற்றுநோய் செல்களை வளரவிடாமல் தடுக்கிறது.

10. எலும்பில் உள்ள தாதுபொருட்களின் அடர்த்தியை அதிகரித்து எலும்பை பலப்படுத்துகிறது.

11. பற்களில் ஏற்படும் பல் சொத்தையை தடுக்கிறது.

12. வாய் துர்நாற்றத்தை நீக்குகிறது.

13. ஞாபக சக்தியை அதிகரிக்கிறது.

14. சருமத்தை பாதுகாத்து இளைமையாக வைக்கிறது.

15. பருக்கள் வராமல் தடுக்கிறது.

15. நரம்பு சம்பந்தமான நோய்களை தடுக்கிறது.

16. மூட்டு வலியை தடுக்க உதவுகிறது.

17. உடலில் ஏற்படும் புண்கள் காயங்கள் விரைந்து குணமாக உதவுகிறது.