Follow Slashdot blog updates by subscribing to our blog RSS feed


Forgot your password?
Slashdot Deals: Cyber Monday Sale Extended! Courses ranging from coding to project management - all eLearning deals 20% off with coupon code "CYBERMONDAY20". ×

Comment it's all about precision (Score 3, Interesting) 160

Sometimes three is just an inherent smarty-pants style to writing academic papers. I lose track of how many times I instinctively try to write something like "utilize" or "make use of" when a simple "use" will work.

But, at least in scientific writing, you use complicated language in order to be absolutely precise about your method and findings (as opposed in particular to scientific journalism...). As an example, I work in the field of direct experimental searches for evidence of interactions between particle dark matter and nuclei. That's a huge mouthful, but every single word in that phrase carries distinct meaning, and if you take any of them out, it is not a correct description of what I do, and may refer to another field entirely.

Now take that kind of precision and discuss an experimental result. "We find that, at 90% confidence level, there is no statistically significant evidence for X". Again, it sounds like buzzwords and jargon, but there is simply no way to turn that statement into "common" English.

Comment give this one a pass (Score 1) 153

Silly me, making the mistake of reading TFA on /. ( aside: what's the proper way to punctuate a sentence ending in /.?)
You want to know how we 'know' all of those things with such great precision? It's all about the scale of temperature fluctuations in the cosmic microwave background. The CMB is a snapshot of the universe some 30k years after the big bang, during the time of first neutralization, when the pathlength of photons quickly (on cosmic scales) went form very short in the hot plasma (think neon light tube) to mostly neutral hydrogen. The spectrum of density fluctuations there tells an incredible amount about how the small perturbations left over from inflation evolved during that early time, and is the main stick by which all of our cosmological models are tested. The incredible agreement with the standard cosmological model and the CMB using only 7 free parameters is probably the most successful accomplishment in scientific history.

Nowhere on the article's page of drivel is the CMB mentioned, nor the WMAP or Planck satellites which were responsible for bringing us that data. I didn't read much of the article, but there is simply no way to speak intelligently about early universe models without the CMB. If you actually want to learn about this stuff, take a look at some of the public stuff NASA has put together for WMAP at ; some of the animations are really quite revealing, and I use them in seminars on the subject all the time. Then if you're still hungry for more and can handle the math, take a look at Dodelson's Modern Cosmology.

Bah, still too angry about this kind of crap. Not a good way to start the week.

Comment weakly interacting != the weak nuclear force (Score 5, Insightful) 93

I got about 1 paragraph into the article before it became obvious that the author had no clue what the hell he was talking about. Maybe the old paper was better, but I don't have the patience to try to find out. From TFA:

They would interact only through the feeble weak nuclear force—one of two forces of nature that ordinarily flex their muscle only within the atomic nucleus—and could disappear only by colliding and annihilating one another

So many things wrong just in that sentence
1) Weakly Interacting Massive Particles (WIMPs) do have very low interaction cross sections (read: rates). There's sometimes an unfortunate ambiguity in the fact that phycisists have no imagination and gave two of the fundamental forces the names Strong and Weak. To say something interacts Weakly means that it interacts by exchange of W or Z bosons, not just that it has a low rate. However the WIMP interaction cross section has been known to be sub-Weak by several orders of magnitude for decades.

2) The Weak force's most obvious manifestation is in the production or absorption of neutrinos (beta decay or inverse beta decay) in a nucleus, but that's certainly not the only place it shows up; it's the mechanism for neutrino-electron scattering, muon decay, and a whole bunch of other stuff up to driving supernova explosions

3) Self-annihilation is the vanilla model for WIMP transformation, but there are plenty of sundaes-with-cherries-on-top models like self-interacting dark matter, which is discussed about 2 sentences later. Also, the chi is the symbol for the supersymmetric neutralino, often equated to a vanilla WIMP, and is not at all specific to the self-interacting dark matter model.

In short, cbtfaij;dr (can't bother to find an intelligent journalist; don't read)

Comment complete and utter rubbish (Score 5, Informative) 225

I'm probably a bit biased here, but also an expert, since I am a physicist who studies dark matter for a living.

The title's question doesn't even make sense! Big bang theory, and in particular studying the exact power spectrum of the cosmic microwave background, is by far the strongest evidence we have for the existence of dark matter and dark energy. All those pie charts you've seen showing the divisions of baryonic matter, dark matter, and dark energy? If they're properly cited, I guarantee every single one of them comes from data from WMAP or PLANCK: CMB experiments! You can't say that dark matter gives you room to invalidate the big bang, because without that we don't have really any strong evidence for non-baryonic dark matter in the first place...

Comment Re:overrated, anyway (Score 4, Interesting) 732

You completely missed the point of the book if that's what you got. What made Ender the supreme commander wasn't his intelligence; he was brilliant, but not significantly more so than many of the other kids. Ender's gift was his empathy: what allowed him to overcome his foes was exactly that he DIDN'T see them as less than human, but that he respected, maybe even loved his adversaries, even as he set up to destroy them.

I won't argue about the rest of the series though

Submission + - LUX experiment rules out low mass dark matter

thegreatemu writes: The LUX collaboration today released the first results using their huge liquid xenon detector to search for dark matter interactions in a live webcast from South Dakota's Sanford Lab. (Here's a copy of the talk and the corresponding paper (warning: PDFs)).
Their conclusion: they see no positive evidence for any kind of dark matter. Moreover, they have pretty conclusively (by a factor of 20!) ruled out conventional dark matter as a source of the low energy signals seen by many of their dark matter competitors (CDMS, CoGeNT, CRESST, and DAMA).

Comment trello (Score 4, Interesting) 115

As a good example, you should take a look at trello , which is basically an organization/design/progress list tool, where each atomic activity is represented by a card. I've been using it extensively for about a year now, and the card+board metaphor really seems to make intuitive sense to everyone I've introduced to it.

Comment it's already out there (Score 1) 84

at least in the particle physics community, practically all anyone uses is open-source code. The most common are GEANT4 for simulating particles interacting with matter, and ROOT which handles data analysis. Both are maintained by dedicated people at CERN.

As to more specialized code, any time I've ever asked someone about their analysis, no matter what institution or relation (or lack of) to me, they've always been happy to share their code source with me. Usually with many caveats about quality, but it's there. The problem for us has always been knowing who to ask, so a dedicated central repository could be interesting.

Maybe a model like the could work. Almost everyone these days puts preprints of upcoming papers on the arxiv. Since there's no review system, you also get lots of garbage from crazies, but it's generally not hard to weed out if you know at least a little about the subject matter of your search, and trivial if you know the relevant big names in your field. In the same vein, a huge code repository where anyone could upload their junky scripts, tagged by name and subject/function/whatever, might work better than it would seem at first glance.

Comment Re:Cognition (Score 4, Informative) 128

Not by any means. For probably the best example, look at the Einstein-Rosen-Podalsky paradox , a simple thought experiment used an attempt to disprove the so-called Copenhagen interpretation of quantum mechanics because it would require the instantaneous transmission of quantum states in such a way that would violate special relativity. People did try to think their way out of it, until Bell's theorem "thought" everyone back into the paradoxical corner - leading to the modern sciences of quantum entanglement.

In fact if you look back, many of the advances in modern physics have come about specifically because of paradoxes arising from thought experiments. See also the ultraviolet catastrophe, or even Schrodinger's cat for that matter.

Comment Re:What about Magic? (Score 1) 136

You still shuffle your deck in Dominion, and it's still possible (though less likely than Magic, granted) to get screwed by chance - your money cards can keep getting spread out just enough that you never manage to get enough buying power on a given turn to buy the top-tier cards. Or you repeatedly get all your good combo-building cards in a row and burn through them without encountering anything practical. I've had both happen...

My biggest problem with Dominion is that you don't really interact with the other players much - it's easily possible to set up a game with none of the "Attack" type cards, in which case you're really just racing N games of solitaire. Even with the attack cards, you don't generally get to respond in any meaningful way - e.g., if you have a Moat you can block the Bandits, but otherwise not. There's no choices, or finite resources - should I save my surprise Bandit Blocker(TM) , or save it for a better opportunity?

16.5 feet in the Twilight Zone = 1 Rod Serling