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How Do We Know the Timeline of the Universe?

thegreatemu give this one a pass (152 comments)

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 http://map.gsfc.nasa.gov/missi... ; 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.

5 days ago

Decades-old Scientific Paper May Hold Clues To Dark Matter

thegreatemu weakly interacting != the weak nuclear force (93 comments)

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)

about 3 months ago

Google Hangouts Gets Google Voice Integration And Free VoIP Calls

thegreatemu grooveip (162 comments)

you've been able to make voip calls using your google voice number from android phones for forever using grooveip (and it's free cousin grooveiplite).

about 5 months ago

Do Dark Matter and Dark Energy Cast Doubt On the Big Bang?

thegreatemu complete and utter rubbish (225 comments)

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...

about 6 months ago

Movie Review: Ender's Game

thegreatemu Re:overrated, anyway (732 comments)

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

about a year ago

Google's House of Cards

thegreatemu trello (115 comments)

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.

about a year and a half ago

Ars Reviewer is Happily Bored With Dell's Linux Ultrabook

thegreatemu Re:Too bad for lunix (181 comments)

Windows 3.1 was DOS based...
98 was the first version of windows that was an actual OS, not a graphical DOS shell

about 2 years ago

How Open Source Could Benefit Academic Research

thegreatemu it's already out there (84 comments)

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 arxiv.org 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.

about 2 years ago

Poor Sleep Prevents Brain From Storing Memories

thegreatemu it's a species survival adaptation (180 comments)

I'm actually only about half-joking here. When you have a newborn, you get practically no sleep for months at a time, and yet people still have multiple kids. Why? Because nobody clearly remembers those early terrible sleepless months!

about 2 years ago

Purported Relativity Paradox Resolved

thegreatemu Re:Cognition (128 comments)

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.

about 2 years ago

The Science of Game Strategy

thegreatemu Re:What about Magic? (136 comments)

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?

about 2 years ago

The Science of Game Strategy

thegreatemu Re:What about Magic? (136 comments)

I agree completely, but luckily there are alternative formats to Constructed decks, in particular Sealed and Draft tournaments. Everyone puts in their entry fee, then builds decks right there from sealed, virgin packs, so there's no "more money = more wins" mechanic. It's the only way I'd ever consider playing in an environment other than casually with friends.

about 2 years ago

Game Review: Street Fighter X Mega Man

thegreatemu smash brothers (79 comments)

Clearly the ideal place for a modern Mega Man is in Super Smash Brothers. 3D look, but essentially a 2D game, and he would totally kick that damn Jigglypuff's ass...

more than 2 years ago

Will Tablets Kill Off e-Readers?

thegreatemu Pixel Qi to rule them all (333 comments)

Maybe, but only once I can actually buy a device with a damn PixelQi screen!

more than 2 years ago

US Presidential Debate #2 Tonight: Discuss Here

thegreatemu Answer the damn questions (706 comments)

I think at this point I would vote for any candidate who would just answer the questions that are being asked...or at least address them tengentially.

There also needs to be a buzzer or something to shut them up whenever they want to discuss their opponent's plans, i.e., put words in their opponent's mouth.

more than 2 years ago

The Linux-Proof Processor That Nobody Wants

thegreatemu Re:The Year of Linux on Desktop Is Now (403 comments)

Except MS office, which most of the corporate/academic world still uses for everything. Yes, Libre Office can do everything as well or in many cases better, but that doesn't matter when someone sends you a pptx file that Impress mangles into an unreadable smear.

more than 2 years ago

Obama and Romney Respond To ScienceDebate.org Questionnaire

thegreatemu Vaccinations (608 comments)

I love how both candidates completely ignored the heart of the vaccination issue, pretending that the reason vaccination rates have fallen is due to people being unable to afford them or supplies running out, rather than the complete failing of our educational system, which has produced a generation of idiots who think that some celebutard's cry about vaccination-caused autism is somehow more worth listening to than a century of sound medical practice. I forget who originated the quote, but it goes something like "Democracy does not mean that your ignorance has an equal voice with my knowledge."

Anyway, just more of the same political dodging. We can't call people reckless morons for endangering themselves AND OTHERS by refusing to get themselves and their children vaccinated, because they might vote for me! I'd really like to have political interviews where we can tie the candidates down and keep asking the same question until they actually answer it,

more than 2 years ago

Obama and Romney Respond To ScienceDebate.org Questionnaire

thegreatemu Re:Climate change (608 comments)

I'm terrified to find myself supporting Romney here, but did you even read your own quote there? He said there was a lack of consensus on "the extent of the warming, the extent of the human contribution, and the severity of the risk."

Now let me quote from your linked article: "The study found that 97 percent of scientific experts agree that climate change is "very likely" caused mainly by human activity."

Nowhere does it say that 97 percent of scientists agree that the average global temperature rise will be X degrees, that the risk is extremely/moderately/not at all severe, or that "mainly" = 100%/90%/80%, etc.

As anti-republican as I am, I have to admit Romney hit this one exactly right. There is overwhelming evidence (which, btw, is way the hell more important than "consensus") that there is warming, and that we are the cause of some significant part of it. But predicting the specific effects, even the exact amount of temperature increase, necessitates a blind faith in models with a pretty poor track record so far.

Of course, the problem is that he's trying to use lack of certainty as an excuse to to avoid taking any action, despite the fact that the science doesn't say anything at all about the best way to fix the issue (or indeed whether it needs fixing...)

more than 2 years ago



LUX experiment rules out low mass dark matter

thegreatemu thegreatemu writes  |  about a year ago

thegreatemu (1457577) 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)."


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