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Submission + - Gamma Ray Bubbles Erupting From Milky Way Center (

jmizrahi writes: A group of scientists working with data from NASA’s Fermi Gamma-Ray Space Telescope said Tuesday that they had discovered two bubbles of energy erupting from the center of the Milky Way galaxy. The bubbles, they said at a news conference and in a paper to be published Wednesday in The Astrophysical Journal, extend 25,000 light years up and down from each side of the galaxy and contain the energy equivalent to 100,000 supernova explosions.

“They’re big,” said Doug Finkbeiner of the Harvard-Smithsonian Center for Astrophysics, leader of the team that discovered them.

The source of the bubbles is a mystery. One possibility is that they are fueled by a wave of star births and deaths at the center of the galaxy. Another option is a gigantic belch from the black hole known to reside, like Jabba the Hutt, at the center of the Milky Way. What it is apparently not is dark matter, the mysterious something that astronomers say makes up a quarter of the universe and holds galaxies together.

Comment ridiculous summary (Score 4, Informative) 169

This is a particularly bad science article. First of all, this research is interesting because they are laser cooling molecules. The article makes it sound like the new thing here is using lasers to cool. Laser cooling of atoms has been around for decades, but laser cooling of molecules is considerably more difficult because molecules have far more resonant transitions than do atoms (this is due to the additional rotational and vibrational degrees of freedom.) Traditional Doppler laser cooling relies on cycling transitions, in which the atoms go back and forth between two levels, losing momentum as they cycle. If the particles can "escape" to other levels, the cycle breaks and cooling stops. Traditionally, in atoms this problem is solved by having other lasers on the table which "plug up" these holes by repumping the atoms back into the cooling cycle. With molecules, there has historically been far too many holes to simply plug them with other lasers.

Second, Fahrenheit? Seriously? Nano/Micro/MilliKelvin is the appropriate unit.

Comment Quark gluon plasma? (Score 5, Interesting) 311

The article seems to say that sufficiently high energy density results in free quarks. I was under the impression that the theory of the strong nuclear force demanded that all observable particles are "colorless," i.e. quarks are never free, but only appear in colorless combinations of mesons and hadrons. Could someone more knowledgeable clarify whether this phenomenon is a violation of the "nature is colorless" law, or whether the article simply does a poor job of explaining a quark-gluon plasma?

Comment Re:Gee, what a concept (Score 1) 233

Its only in the last 200 years or so that we have had the idea that musicians should make money for a recording of their performance.

Yes, it sure is shocking that nobody thought to sell music recordings before 1904. It's almost like the technology to record and play back music didn't even exist.

Honestly, since there is no way they are ever going to stop filesharing, its not a bad idea to legalize it IMHO.

That's a ridiculous argument, seeing as though they are never going to completely stop ANY crime.

Comment Re:meh (Score 2, Informative) 320

This is obviously a personal preference thing, but I had the opposite experience. I played Civ II for many years, then had a long break, and years later tried Civ IV. I found it to be better than Civ II in a lot of ways. There were all sorts of annoying things in Civ II, like losing whole stacks of units when one gets attacked, or the ability to deposit entire armies outside your opponents city and then declare war, during which you could use his railroads. Civ IV has numerous small improvements, which for me added up to make a big difference. The basic gameplay, of course, is the same.

Comment Re:No details but interesting (Score 3, Interesting) 129

The difficulty in achieving entanglement comes from the system being perturbed at random from thermal vibrations.

That's not quite accurate. The difficulty in achieving entanglement comes from the inherent difficulty in isolating a quantum system from its environment. In the case of ion trap quantum computing, for example, this isolation is achieved through an ultra high vacuum. Ultra high vacuum has its own difficulties, but does not require cryogenics.


On Social Networks, You Are Who You Know 171

santosh maharshi writes "On social networks like Facebook, even if you have kept your profile very private, people can just look at your friends list and infer lots of vital information about you. Most of the social networks like Facebook and LinkedIn allow people to see your picture and your friends list as part of the open access for visitors (the article says that only 5% of Facebook users have bothered to hide their friends list). In a study titled You Are Who You Know: Inferring User Profiles in Online Social Networks (PDF), conducted by Alan Mislove of Northeastern University and his colleagues at the Max Planck Institute for Software Systems, an algorithm was tested that can accurately infer the personal attributes of Facebook users simply by looking at their friend lists. 'At Rice [University], the algorithm accurately predicted the correct dormitory, graduation year, and area of study for the many of the students. In fact, among these undergraduates, researchers found that “with as little as 20 percent of the users providing attributes we can often infer the attributes for the remaining users with over 80 percent accuracy."'"

Comment Re:Exactly. Using open wifi is not stealing. (Score 1) 263

While in general I agree with you, I don't think it's quite that crystal clear. Let's suppose that the person with the internet subscription and his neighbor are both technologically clueless. Person A buys a device which, by default, allows anyone within range internet access (a wireless router). Person B buys a device which, by default, connects to the closest available network (a Windows computer). Both these devices are fully legal. Can you really say that Person B is stealing when he turns on his computer and discovers he has internet access? Maybe he doesn't even realize that you have to pay for such things. He could be a complete moron. The point is, all he did was turn on his computer and use its native features. The other reason the theft analogy breaks down is that in most cases, the person with the internet subscription does not suffer any losses from the freeloader, unless he's downloading tons of data. Except for that case, it's more akin to somebody using your driveway when you're out of town. Is that really stealing? Trespassing seems a more appropriate analogy.

Comment Re:Ah, I unplugged the atomic clock... (Score 5, Interesting) 193

You are absolutely correct, the time measured by such a clock is going to be dependent on general relativistic effects, most prominently by distance from the mean geoid. However, I fail to understand how you jump from that to concluding that it's useless. For example, you could use such a clock to make precision measurements of general relativity and test possible extensions. Moreover, a clock that sensitive should be able to "feel" changes in gravity caused by density fluctuations in the Earth. This could help find oil deposits, for example. The summary says as much. Generally speaking, you NEVER lose by increased precision. It is true that if your specific application is limited by low precision in some other component, you won't gain by increasing precision somewhere else. However, that's not the case here. I'll admit that I don't know enough about GPS and satellites to answer your specific question, but my impression is that they currently ARE limited by time standards.

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