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British Deputy Prime Minister Nick Clegg 'Kills' Snoopers Charter

bjorniac Re:going lib dem this time (47 comments)

We're in the EU, we're not dead. Are you confused, perhaps about the Euro?

about a year ago

How Scientists Know An Idea Is a Good One

bjorniac Re:Read the literature... or not (140 comments)

A big part of the problem is that there are few negative results in scientific literature. Ever found a paper with a clear negative outcome? I didn't.

Perhaps you should publish this finding.

about a year ago

A Quarter of Sun-Like Stars Host Earth-Size Worlds

bjorniac Re:Streetlight effect? (105 comments)

The answer is that it's not much more difficult, but a lot more time consuming (gleaned from going to talks on the subject, not my area of expertise).

There are two basic ways that these planets are observed: They make the stars they orbit wobble (the basic 2 body problem - each body orbits the center of mass of the pair) and they dim the light from the star when they pass in front (like an eclipse).

The time problem comes from the fact that orbits are longer for objects more distant from the star. If we make the simplification that the orbit of the planet is basically circular, the time period for an orbit increases as radius^(3/2). (Insert semi-major axis for radius for non-circular). The standard is about three events separated by equal times to count as an observation - you have to wait to see an event at least twice to know the time period and so infer the radius of orbit, and once again to remove some flukes. Hence you're having to wait a long time looking at a star to see this happen.

Now, on top of that you've got the possibility that there's more than one planet, that the earth-like planet isn't the dominant mass, etc etc. This can all be cleverly dealt with (multiple wobbles, multiple eclipses) but it adds time to the confirmation process.

To give an example: Suppose you were somewhere near Proxima Centauri, and making the relevant observation looking for Earth. It would take at least three years to detect Earth, even if your telescope was amazing. Dynamics of the system would pick up the effect of Jupiter on the sun first, for the wobble detection (you wouldn't get much eclipse given the angle between the plane of the solar system and the position of PC) and it might take quite some analysis to pick up Earth at all given the effects of all the other planets.

Anyway, I'm sure some astro people can give a much better version of all this. Suffice to say that we aren't looking for Earth like planets at Earth like radii yet, but I imagine over the next ten to twenty years there will be a lot of poor graduate students analyzing data desperately looking for Gallifrey.

about a year ago

Does the Higgs Boson Reveal Our Universe's Doomsday?

bjorniac Re:jesus, what a shitty first article (421 comments)

I can't do you a car analogy, but here's the very basic idea (massively watered down, physics friends - I know, I know, but let's try to keep this simple enough):

Consider a ball rolling on a set of hills and valleys. For our purposes, let's make it simple and 2-dimensional, but you can generalize quite easily. A 'vacuum' for this system equates to being at the bottom of a valley, as this is a point of lowest energy, and things tend to roll down and end up in the bottoms of valleys. The shape of the hill (called a potential which relates strongly to potential energy you might recall from high-school/college intro physics) determines the physical properties of the particle like its mass.

However, the valley you're at the bottom of might not be the lowest point overall in the system, it might just be a local minimum. This is what we call a 'false vacuum' in particle physics: A point in the system which looks to all intents and purposes to be a minimum in a small locale. However there could be a lower point.

Now, when you're just dealing with classical systems (like a ball rolling on a hill) this is all well and good. However in a quantum theory the wavefunction describing the particle can happily have non-zero values anywhere and (again very roughly speaking) this means that you can 'tunnel' from one minimum to another with some probability - breaking your false vacuum and moving you to another one. This tends to be in a downward motion - you go to a vacuum lower than the one you're in. This means that the mass of the particle will appear to change, and so all the physics you observe will be completely different.

These effects can related to all kinds of cool physics - the ones often talked in about popular-ish media are inflation/cosmological constant type things - if there is some energy associated with a particle being in a certain state, this can look a lot like a cosmological constant and produce and accelerating universe. However, if this isn't the global minimum there is a probability at all times that the tunneling effect mentioned above can happen, turning off the acceleration.

Anyway, hope that helps. Sorry I couldn't give you a car analogy, but here's an effort at one:

You (the particle) get a Mustang for your 17th birthday (lucky you!) and all your friends are jealous. You then start to think that since all the cars you see around you are worse than yours that you have the best car ever, and act accordingly. However, there is a chance that one day you'll catch glimpse of something sublime - an E-type. And your world view will change - there's a better car out there! Yours is only a false "best car ever", and now you have to act according to your new knowledge, which changes your behavior. Eventually you save up and buy yourself an E-type, moving to the 'true vacuum' / best car ever, and all your interactions with your friends are now based on this new car.

OK, that was godawful. But I tried.

about a year ago

Ask Slashdot: How Do I Get My Spouse To Start Gaming With Me?

bjorniac A few simple ones (550 comments)

As others have suggested, co-op games are certainly the way to make things interesting and fun, especially when there's going to be an obvious skill imbalance. Also try to pick things with a very shallow learning curve - if she hasn't played games before, just getting the coordination with a controller or mouse can be frustrating enough.

Games that have a low punishment for failure are going to be key when someone is first starting. This isn't quite the same as a shallow curve, but you want a game that is forgiving of your errors whilst you learn to play. Similarly something that isn't high pressure is probably good for early games. Left 4 dead, despite its excellence, probably isn't the best way to get into things (but will make an incredible game later if she gets into it!)

There are a couple of games I've found that can be really great fun in this way, and depending on /her/ tastes, you should find something:

First there's Trine (and its sequel). You can pick this up quite cheaply, and it's a lovely fairytale of a game, beautifully drawn, gently but excellently narrated. It's a 1-3 player co-op platformer/puzzler (I played it with my partner who loved it) and having more people massively increases the fun. It also doesn't do the usual gendered thing with games of having "chick-armor" or "all people are male" - the female character (one of the three players) is very nicely done. Set on an easy mode it's simple to learn, works excellently with controllers and doesn't require too much coordination for a newcomer. If you pick your timing right, you can get it for about five dollars on Steam.

Another great coop game is Civilization V. I know it's not the most hardcore in terms of strategy of the series, (and I'm presuming as a gamer you know the series) but its very easy to learn and playing as a team, either hot-seat or with two computers, is very satisfying. A more experienced player can provide cover the learner in terms of military protection etc, or just set the game on sufficiently easy mode whilst she learns the basics. In coop mode you can learn a section of the game at a time whilst your partner takes care of the rest, so she can focus on military strategy and world domination whilst you build the empire to fund it, or she can learn to manage cities to produce culture and science whilst you cover her borders. The turn based nature of the game makes it easy for teaching someone how to play, and it offers a ton of depth and replayability.

On the RPG front, Torchlight is marvelous, with its sequel being a great 2-player game. It's diablo-esque, but maintains the joys of D2. It can get a bit hectic on occasion, which is very frustrating, but with a co-op game again you can cover her.

On the FPS/strategy, Orcs Must Die (2) is a nice one, but does suffer horrendously from a couple of things - it has a nice learning curve, but can get overwhelming fast which leads to frustration. Also it has tongue-in-cheek cliched characters which at first will look rather like the female is supposed to be the stuff of adolescent fantasy. It's not as bad as many out there, but let's just say that her armor is less than optimal in some regions.

Hopefully that should be something to get you going. Ignore the people who say "Don't do it" - of course you should try out new hobbies together, and you may find an excellent way to have fun together. My partner and I game together often, and sometimes at long distance is a great way to spend time "together" when you're apart.

about a year ago

Astronomers Discover a Group of Quasars 4 Billion Light Years Across

bjorniac Re:inflation ok here? (106 comments)

It's a good question. I think you've gotten things a little backwards, though, with regars to the problem of propagation - inflation is a proposed explanation for propagation in the sense that it allows otherwise separate regions of the sky to have been in causal contact in the past. But this certainly does have impact upon the current inflationary paradigm in the following sense:

If there were large structures or large inhomogeneities in the early universe (before inflation) then it would be hard to get inflation going. The basic models of inflation contain a field whose energy can be decomposed (and I'm playing very fast and loose here) into three parts: Potential, Kinetic and fluctuations. From these parts, we say that if the potential is large enough, the inflaton undergoes a "slow roll" down the potential during which our regular inflation happens. Fluctuations are treated as perturbations on this background, and it's from these that we expect to see the everyday structure in the universe. A warning though: We don't know the physics that causes these fluctuations to stop being quantum fluctuations and become classical perturbations in matter on this background.

Now, if the fluctuations are too big, this model breaks down - the inflaton can't be high enough up its potential, and so slow roll can't happen. Hence before inflation we have to assume that the universe is largely homogeneous and isotropic, and fluctuations begin very small (technically in the "Bunch-Davies vacuum state).

A big inhomogeneity AFTER inflation isn't too bad - it could well be that this is just the result of one of the longer wavelength fluctuations. Of course, one would then have to explain /why/ this wave in particular had such a large amplitude, but this really doesn't contravene inflationary models, it merely adds a new question about the initial conditions.

Now, if we had been dealing with a serious overdensity (tons of quasars in the same spot) rather than a large strung-out structure, we would certainly have a problem with inflation, but so far as I know this isn't too big of an issue.

Disclaimer: I work on the mathematical structure end of things, not the computation or observation, so there are certainly people more qualified than I, to whom I would happily defer if they want to post!

about a year ago

Ask Slashdot: What Video Games Keep You From Using Linux?

bjorniac Re:Microsoft Office (951 comments)

I write my CV in LaTeX. It's incredibly easy and spits out a good looking PDF. I'd wager I'm far from unique amongst people in my field (physics) in doing this - we write all our papers that way, most presentations too, so it seems a logical step.

about a year ago

Alpha Centauri Has an Earth-Sized Planet

bjorniac Re:Dear /S/cientists (152 comments)

A figure-8 is quite hard to find, since the symmetries involved would require almost perfectly equal masses between the stars and perfectly circular orbits of the stars. (This is from memory running simulations a long while back). However it is certainly possible to have a planet be orbiting one star for a few loops and then be captured by the other, orbit it a few times and keep getting passed back and forth.

The basic condition you need for this is for the planet to have enough energy to get over the maximum between the two gravity wells of the stars. If you think of kinetic and potential energy being like those of a ball rolling on a set of hills, you'd say that the ball is either trapped between two peaks or not. However with this case it would appear that the hills themselves are moving, so the "hump" between them will grow and shrink with time, sometimes letting the ball pass between valleys, sometimes trapping it in a single valley for a few cycles.

What's really remarkable is that this is all do-able without too much technical knowledge. You'd need:

About a second year undergrad level of physics - You could do it with Newtonian mechanics, but Lagrangians make it a LOT easier);

A bit of programming technique (two days or so with MATLAB and you'll get the basics of ODE solvers).

A LOT of patience :)

As an aside, you could just grab the game "Osmos" which has a lovely set of orbital levels that basically implement this :) I strongly suspect whoever was involved with it was well educated in physics, as finding the stable orbits they have requires an understanding of conservation laws and use of a symplectic integrator (eg Verlet's algorithm) to implement time updates, instead of just using Newton's method.

about a year and a half ago

Alpha Centauri Has an Earth-Sized Planet

bjorniac Re:Dear /S/cientists (152 comments)

It's rather the same way the moon orbits the earth. If you have a binary system, a planet can quite happily orbit very close to one of the two stars so long as the distance between the planet and the star it orbits is smaller than the distance between stars. The pair of stars will orbit their mutual center of mass, and the planet will orbit a single star.

Of course, the three body problem is an open question in physics, but if you make the assumption that one of the masses is much smaller than the other two it (which is the case for planets orbiting stars) it becomes quite solvable, especially if you're happy with numerical simulations of orbits.

A similar situation is possible if the planet is a long way from the pair of stars, and would then orbit their center of mass. That isn't the case here, but is certainly a feasible solution to the problem. You only really get orbits that are highly erratic when the planets orbital radius is over a quarter of the distance between the stars.

Throughout this I've assumed equal mass stars. Feel free to put a factor of M1/M2 in front of every distance I gave for non-equal mass stars.

about a year and a half ago

Valve Reveals Gaming Headset, Teases Big Picture

bjorniac So, its a hat. (151 comments)

Well played, Gaben, well played.

about a year and a half ago

Valve Job Posting Confirms Hardware Plans

bjorniac Re:Keyboard and mouse hasn't changed for a reason (219 comments)

Well, some games have different gun spreads when you run as opposed to walk, so perhaps the spread could be scaled by movement speed, ie radius of spray pattern proportional to movement speed. And/or you could implement radius of footstep sound carrying proportional to speed. That way there would be a tactical decision about how fast to run somewhere.

about a year and a half ago

With 'Access Codes,' Textbook Pricing More Complicated Than Ever

bjorniac Re:Mark of a shitty instructor (400 comments)

Standardization. Getting 30-40 (or in some cases 200-300) students to have the same version of a textbook basically requires that you set the current edition, as you can't guarantee that older editions will be available. This has to be done well in advance and normally agreed first with the department (who may have already forced their choice of textbook on you) then the university bookstore, who are also usually in it for their cut.

Your professor gets nothing (except headaches) out of their choice of textbook. The administrators won't let you pick anything that isn't a current edition. It's a pain for us too - I don't like having all my sections moved around, set standard questions shifting etc. It makes more work for me to go through and test-run exercises to see which are good or bad etc.

about a year and a half ago

Fans Bring Back Half Life Game Series: Black Mesa Mod Launches 9/14

bjorniac Re:No Xen. (133 comments)

Croteam did this with the HD versions of Serious Sam, they're actually quite nice.

about a year and a half ago

Calculating the Cost of Full Disk Encryption

bjorniac Re:No kidding (242 comments)

"Tomorrow", for one.

OP was using hyperbole, all day names end in "y", hence he's implying that the lady at work forgets her password every day.

about a year and a half ago

Faculty Votes For Open Access Policy At UC San Francisco

bjorniac Re:Let the Seed Grow (146 comments)

You know, I was trying to be polite - there's no need to be rude in response. You generalized to all social sciences, I showed that you were wrong with this generalization - that indeed some of the social sciences (namely sociology, with which I have quite some familiarity now) are sciences. Then you respond by saying things related to the outcome of wars. I then tell you that your statement isn't relevant as it doesn't address the point that indeed sociology is a science. Therefore the statement you initially made "Social Science isn't science" is false, by my counterexample. You simply tried to move the goalposts to mean "this set of things (most of which wouldn't qualify as social science) aren't science".

Of course, I agree that history isn't a science. But I don't think many people would put it in a "social sciences" category, for myself it falls squarely in humanities.

about 2 years ago

Faculty Votes For Open Access Policy At UC San Francisco

bjorniac Re:Let the Seed Grow (146 comments)

I think you're confused about what sociologists do. They are not concerned with the outcome of wars, but more with the impact of social policy or phenomena. People as individuals may not obey immutable laws, but en mass they can be modeled quite effectively, just like gasses of particles can be modeled without knowing the motion of any individual particle. It is impossible to model the individual particles accurately due to their number, but given extensive properties (Temperature, Density, Volume etc) I can tell you how the gas as a whole will behave. Based on the Copenhagen interpretation of quantum mechanics, I can never tell you exactly how any one particle will behave, only give you probabilities of certain behaviors, just like people. They aren't "rational".

You absolutely can say within social science that certain things will happen at certain rates within tolerances - this is exactly what my partner did in her PhD. She performed statistical tests to show (at a 99% level of confidence) differing care-giving levels (measured by hours worked for family members) based on variables such as fertility of the individuals concerned.

She can certainly tell you, with 99% accuracy, based on the number of children a woman in Togo has and her desired levels of fertility, what the probability of her getting AIDS in the next year is. She can compare this with Benin, which has a different social support structure, and show that, for instance, the more localized family networks reduce this fertility desire and in turn reduce instances of people developing AIDS. And she can absolutely tell you, ahead of time, what the impact of building a new road to a remote village will be in terms of fertility desires, migration and infection prevalence. With measurable, repeatable numbers, statistical significance, etc. If you changed "fertility preference" for "quark mass" and connectivity of a village for "phi^4 coupling" what she and I do end up looking almost identical, so I can't claim to be doing science if she isn't.

about 2 years ago

Faculty Votes For Open Access Policy At UC San Francisco

bjorniac Re:Let the Seed Grow (146 comments)

I've got a PhD in physics, my partner a PhD in Sociology. Her dissertation consisted of obtaining qualitative data regarding a social phenomenon, building a model, collecting quantitative survey data and statistically analyzing that data to test hypotheses drawn from the qualitative data.

So: Model building from a theoretical basis, hypothesis testing from observed data and analysis. That, my friend, is science. The only difference between her work and that of my colleagues who are experimentalists is that her instrument was a survey instead of an atomic clock.

I, on the other hand, did a bunch of maths, and was an exception in my field by being able to test my work against observations. A master's in Polisci might not have got you close to science, but don't presume that science isn't being done in the social sciences - it is, and done right it can be of vital importance to the society we live in.

about 2 years ago

Geeks In the Public Forum?

bjorniac Re:Technocrats (326 comments)

You need to convince just over 50% of the _voting_ population, and sometimes not even that. This tends to be much less than half of the population for most countries. Turnouts rarely break 80% in most countries, in US presidential elections it doesn't exceed 60% these days - http://www.infoplease.com/ipa/A0781453.html - so really it's about 30% of people you actually need to convince strongly enough to actually vote for you.

In some systems it can seem fairly ridiculous: The UK 2005 General Election was won comprehensively (in terms of seats, and hence power) by the Labour party. They had 56% of the seats with just 35% of the vote. The turnout was around 61%, meaning that just 20% of the electorate voted for them. http://www.ukpolitical.info/2005.htm

about a year ago



Best Computerless VOIP Phone

bjorniac bjorniac writes  |  more than 6 years ago

bjorniac (836863) writes "After a series of unfortunate events I am no longer willing to tolerate my phone service provider. It seems that a number of devices that connect directly to a wireless router are available allowing the user to cut out the telephony parasites. Do any Slashdotters have recommendations/horror stories to share?"


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