Lecture explores string theory


first_imgString theory, a so-called “theory of everything” in physics, is a popular topic among more than just scientists. Juan Maldacena, professor of theoretical and astrophysics at the Institute for Advanced Study and one of the foremost researchers in the field of string theory, delivered a lecture Wednesday on the subject of chromodynamics, string theory and black holes. Maldacena is most well-known for his 1997 paper on the large N limit of superconformal field theories and supergravity, which is the most-cited high energy physics paper of all time. Maldacena began his talk by discussing the close relationship between quantum chromodynamics, a type of quantum field theory, and gravity theories, namely quantum gravity. “The equality between these two things would be that the quantum field theory living on some space is equal to the quantum gravity living in the interior of that space,” Maldacena said. “The idea is that the physics in the interior can be described by the physics that happens on the boundary.” In particular, Maldacena discussed supersymmetric versions of this theory using the maximum number of supersymmetries, although these versions are difficult to experimentally confirm. One of the reasons for the maximum supersymmetry assumption in the theory is that is greatly simplifies the case and makes complicated physics a more tractable problem, Maldacena said. “There’s this joke about a farmer who had a cow, and he needed to increase milk production,” Maldacena said. “So he hires a veterinarian and a physicist to help him and the veterinarian tells him, ‘Well you should feed the cows better, exercise, blah, blah, blah.’ And then the physicist says, ‘Well, let’s first assume that we have a spherical cow.’ So this theory can be called a hyperbolic cow.” In order to work out these theories, Maldacena used anti-de Sitter’s space, which comes from the de Sitter space used to describe cosmological expansion. “In some sense, anti-de Sitter space is like a gravitational box that does not allow massive particles to reach the boundaries,” Maldacena said. “So if you sit in the middle of anti-de Sitter space and you throw a rock, after awhile the rock will come back to you. If you shoot a gun, then that’s not a very good idea.” Using this approach, a natural duality arises between quantum field and gravity theories, which allows researchers to investigate fundamental questions in physics, he said. “Duality in this relationship means, ‘Take some parameter, and when the parameter takes some set of values, say small ones, then one description is easy,’” Maldacena said. “‘Then if it takes another set of values, let’s large ones, then the other description is simple.’” When looking at systems of weakly-interacting gluons, essentially free ones, the string theory is the simplest description. When there are strongly-interacting gluons, the problem is still well-defined but difficult to analyze with string theory, in which case gravitational descriptions are better because the radius in the space is much larger. This leads to a good approximation of more complicated string theory by relatively simple gravity ones, Maldacena said. “The good thing that gravity does for us is it allows us to solve the quantum field theory in a simple way,” Maldacena said. “However, there are things that we can learn about gravity from the field theory. A particularly interesting thing is that it’s useful for understanding quantum aspects of a black hole.” Black holes are gravitational collapses, where nothing can escape once the event horizon, a sort of boundary of the black hole, is passed, Maldacena said. But according to quantum dynamics, they can emit radiation, where the temperature at which the radiation is emitted is inversely proportional to the size of the black hole. “This effect implies that the smaller you make the black hole, the hotter the temperature is,” he said. “You can have the paradoxical equation of a black hole that can be white. So you have white black holes.” In physics the notion is that whenever there’s a temperature, something is moving, Maldacena said, and one of the hot questions in the field is to describe what goes on in the interior of a black hole. Maldacena said these complex descriptions of black holes can also be applied in a more generalized way to hydrodynamics, underscoring the fundamental nature of his research and the discipline of physics as a whole. “As physicists, one of the laws of physics is that you take a problem and investigate by making it simpler,” Maldacena said.last_img read more

Tough luck for Gilliland


first_img“I don’t know what the 38 was doing,” Kahne said. “First off, he’s hard to pass. Then you get by him and he’s two laps down and he starts battling. I let him go and he still didn’t pass me. I have no idea what he was thinking, but that’s the way it goes.” Gilliland said the goal was to keep from wrecking despite the “hairy” track conditions. “(The wrecks) were right in front of me,” he said. “It was a busy day for that. We’re happy that we brought the car home in one piece. That’s a lot more than some other guys can say.” EARNHARDT’S GOOF Dale Earnhardt Jr.’s momentary brain hiccup cost him a likely top-five finish. Late in the race, Earnhardt was running sixth when he followed Jeff Burton into the pits during a caution with 16 laps to go. There was only one problem: Burton was pitting because his car was broken and needed immediate repair. The pits weren’t open yet, signaled by a red light at the start of pit road. As a result, Earnhardt was given a penalty and had to start at the back of the pack. He finished 11th. “The pit road was closed and I didn’t see, or wasn’t looking,” he said. “I didn’t even think if it was closed or open. You’re not thinking about that. “I’m sad for my team because we should have finished fifth or sixth. But I’m just happy we got to finish one, finally.” Earnhardt needed a good finish after two DNFs to start the season, a result that put him in jeopardy of souring his season after just three races. Instead, he moved up 12 spots from 40th to 28th. Drivers must be in the top 35 after the first five races in order to be locked into the field each week. THANKS FOR NOTHING Casey Mears finished 40th after getting caught up in a wreck caused by Orange County’s Robby Gordon on the eighth lap of the race. “It amazes me – every time I think Robby can’t do anything more stupid than he’s already done, he one-ups himself,” Mears said. “It’s ridiculous. He’s trying to pull off something in the first opening laps when it means nothing. I guess he’s trying to be a hero.” 160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set! LAS VEGAS – Considering there are seven former Chase for the Nextel Cup participants behind him in the standings after three races, life could be worse for David Gilliland. The former Inland Empire resident finished 21st in Sunday’s NASCAR race at Las Vegas Motor Speedway, a result that dropped him one spot to 12th in the season standings. After avoiding several wrecks, including a pair of spinning cars right in front of him, Gilliland was eventually lapped by race leader Jimmie Johnson on the 90th lap. He later went two laps down after a pit stop with 50 laps remaining, effectively ending his chances at a top-20 finish. “We needed to start where we finished with our car,” he said. “It would have been great. But we didn’t.” Gilliland drew the ire of driver Kasey Kahne after a wreck late in the race. Kahne was running in the top 10, but spun out and crashed while driving next to Gilliland’s No. 38 M&Ms Ford with about 20 laps remaining. The two cars didn’t make contact, but Kahne blamed Gilliland for the incident. After the race, he approached Gilliland’s hauler before being shooed away by crew members. center_img “We just kind of struggled with the car, but we weren’t the only ones today, you know,” he said. Gilliland crashed his primary car during qualifying on Friday and was forced to use a backup. NASCAR rules dictate that switching cars after qualifying necessitates starting from the rear of the field. last_img read more

Virgin Money sees mean gender pay gap narrow to 325


first_imgVirgin Money has a mean gender pay gap of 32.5% for hourly fixed pay at April 2017, compared to 36% in April 2016.The organisation has reported snapshot data for 5 April 2017 in compliance with the government’s gender pay gap reporting regulations. The data has been published on the government’s gender pay gap viewing service alongside supporting information.The median gender pay gap for hourly fixed pay is 38.4% at April 2017. Virgin Money had a 39% median gender pay gap in April 2016, as detailed in its 2016 annual report.The mean gender pay gap for bonus pay is 45.3% in the year up to 5 April 2017, and the median gender pay gap for bonuses is 40.7%. For the 2016 performance year, 88.7% of the organisation’s female employees received bonus pay, compared to 90.1% of male employees.Just over one-third (35%) of employees in the highest pay quartile at Virgin Money are women, compared to 48% in the second quartile, 64% in the third quartile and 73% in the lowest pay quartile. This represents a gender pay gap of 9.7%, 3.8%, 2.8%, and -0.7% across the quartiles, respectively.Virgin Money has set a target to achieve a 50:50 gender balance across the business by 2020, within a 10% tolerance.The gender pay gap reporting regulations require organisations with 250 or more employees to publish the difference between both the mean and median hourly rate of pay for male and female full-time employees; the difference between both the mean bonus pay and median bonus pay for male and female employees; the proportions of male and female employees who were awarded bonus pay; and the proportions of male and female full-time employees in the lower, lower middle, upper middle and upper quartile pay bands.In April 2017, the Government Equalities Office launched the online gender pay gap viewing service to allow the public to see the data that employers have published so far to fulfil their gender pay gap reporting obligations.A spokesperson at Virgin Money said: “We are proud to be the first FTSE [organisation] to publish its 2017 gender pay gap figures under the new legislation. We have made progress over the last year, with our mean gender pay gap reducing from 36% to 32.5%. This gap is not acceptable and we are committed to reducing it.“We know that as we move towards a more balanced workforce at every level the gender pay gap will reduce substantially. We are heading in the right direction, narrowing the gap and building trust through visibility at the same time.”last_img read more