Follow Slashdot stories on Twitter

 


Forgot your password?
Close
typodupeerror
×
Science

Cosmologists Show Negative Mass Could Exist In Our Universe 214

Posted by Unknown Lamer from the beam-me-up dept.
KentuckyFC (1144503) writes The idea of negative mass has fascinated scientists since it was first used in the 16th century to explain why metals gain weight when they are oxidized. Since then, theoretical physicists have shown how it could be used to create exotic objects such as wormholes and the Alcubierre warp drive. But cosmologists' attempts to include negative matter in any reasonable model of the cosmos have always run into trouble because negative mass violates the energy conditions required to make realistic universes with Einstein's theory of general relativity. Now a pair of cosmologists have found a way around this. By treating negative mass as a perfect fluid rather than a solid point-like object, they've shown that negative mass does not violate the energy conditions as had been thought, and so it must be allowed in our universe. That has important consequences. If positive and negative mass particles were created in the early universe, they would form a kind of plasma that absorbs gravitational waves. Having built a number of gravitational wave observatories that have to see a single gravitational wave, astronomers might soon need to explain the absence of observations. Negative mass would then come in extremely handy.
Perl

Ask Slashdot: Choosing a Web Language That's Long-Lived, and Not Too Buzzy? 536

Posted by timothy from the perl-6-will-blow-them-all-away dept.
adelayde (185757) writes "In my day job, I work on a web based service with a lot of legacy code written in that older (and some may say venerable) web-scripting language, Perl. Although we use Modern Perl extensions such as Moose, the language just seems to be ossifying and we're wanting to move to a more up-to-date and used language for web applications, or even an entire framework, to do new development. We're still planning to support the legacy code for a number of years to come; that's unavoidable. This is a fairly big project and it's mission critical to the business. The thing we're afraid of is jumping onto something that is too new and too buzzy as we'd like to make a technology decision that would be good at least for the next five years, if not more, and today's rising star could quite easily be in tomorrow's dustbin. What language and/or framework would you recommend we adopt?"

Comment Re:Don't. (Score 1) 408

we..er..a friend of mine has a smaller dog who rolls over to get his belly rubbed for anyone. but if the front door is closed and he hears something outside, he goes nuts barking. he also barks at the wind blowing, his shadow, and when we open the door and wake him from his nap. and the A/C unit coming on. and when i move too suddenly when he's asleep on my lap.

Comment don't be afraid (Score 1) 172

by mrzaph0d (#46936147) Attached to: Ask Slashdot: Beginner To Intermediate Programming Projects?

to start something you're not sure you can finish. i wrote a framework in perl to generate some pdf reports, complete with graphs and automated text. took me quite a while, and a lot of "i'll come back to this part later". i went from the script being used to piece together bash/shell commands, to it doing everything.

but the point is, i kept at it. taking a little part at a time and futzing around with it till it worked a little better.
Books

Seattle Bookstores Embrace Amazon.com 83

Posted by samzenpus from the keep-your-enemies-close dept.
An anonymous reader writes "Even though many independent bookstores around the country blame their closing on competition from Amazon.com, bookstores in Seattle are booming thanks to Amazon's growth. It turns out many of the thousands of new workers at their downtown headquarters are avid readers who prefer shopping at the local stores. '"A lot of our customers work at Amazon," said Tracy Taylor, the general manager at the Elliott Bay Book Company, one of the city's largest independent booksellers. The store, about a mile from Amazon headquarters, last year earned what Ms. Taylor called the "first substantial profit" in almost 20 years, enough to even pay employee bonuses.'"
Science

LHCb Confirms Existence of Exotic Hadrons 99

Posted by Soulskill from the pushing-back-the-boundaries-of-physics dept.
An anonymous reader sends this news from CERN: "The Large Hadron Collider beauty (LHCb) collaboration today announced results that confirm the existence of exotic hadrons – a type of matter that cannot be classified within the traditional quark model. Hadrons are subatomic particles that can take part in the strong interaction – the force that binds protons inside the nuclei of atoms. Physicists have theorized since the 1960s, and ample experimental evidence since has confirmed, that hadrons are made up of quarks and antiquarks that determine their properties. A subset of hadrons, called mesons, is formed from quark-antiquark pairs, while the rest – baryons – are made up of three quarks. ... The Belle Collaboration reported the first evidence for the Z(4430) in 2008. They found a tantalizing peak in the mass distribution of particles that result from the decays of B mesons. Belle later confirmed the existence of the Z(4430) with a significance of 5.2 sigma on the scale that particle physicists use to describe the certainty of a result. LHCb reports a more detailed measurement of the Z(4430) that confirms that it is unambiguously a particle, and a long-sought exotic hadron at that. They analyzed more than 25,000 decays of B mesons selected from data from 180 trillion (180x10^12) proton-proton collisions in the Large Hadron Collider."
Programming

Does Relying On an IDE Make You a Bad Programmer? 627

Posted by samzenpus from the speak-up dept.
itwbennett writes "Writing about his career decisions, programming language choices, and regrets, Rob Conery says that as a .NET developer he became more reliant on an IDE than he would have with PHP. Blogger, and .NET developer, Matthew Mombrea picks up the thread, coming to the defense of IDEs (Visual Studio in particular). Mombrea argues that 'being a good developer isn't about memorizing the language specific calls, it's about knowing the available ways to solve a problem and solving it using the best technique or tools as you can.' Does using an IDE make you lazy with the language? Would you be better off programming with Notepad?"
Science

Government Lab Uses Smartphones To Measure Gamma Ray Exposure 105

Posted by samzenpus from the hulk-phone-is-strongest-there-is dept.
KentuckyFC writes "Back in 2008, Slashdot reported that researchers were developing ways of turning cellphones into radiation detectors. Since then a few apps have even appeared that claim to do this. However, convincing evidence that they work as advertised is hard to come by. Now government researchers at Idaho National Labs have created their own app that uses an ordinary smartphone as a gamma ray detector, put it through its paces in the lab and published the results. The pixels in smartphone cameras can detect gamma rays in the same way as they pick up visible light. So when the lens is covered, the image should reveal evidence of gamma ray exposure once other noise has been removed, such as that from heat and current leakage. These guys have tested several types of Android smartphone with a variety of gamma ray sources at various different doses. The researchers say the phones give a reasonable measure of radiation dose, can detect the direction of source (by comparing the measurements from the front and back cameras) and can even measure the energy of the gamma rays by measuring the length of the tracks that appear in the image. While the results do not match the quality of bespoke detectors, that may not matter since in many circumstances cellphones are likely to be the only sensors that are available. That could be useful for emergency services, air travelers wanting to monitor their extra radiation dose on routes over the arctic and people who live in areas with a higher than average background radiation level."

Slashdot Top Deals

Work is the crab grass in the lawn of life. -- Schulz

Close