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Comment: Re:Top Speed ? (Score 2, Informative) 229

by GileadGreene (#32935994) Attached to: Ikaros Spacecraft Successfully Propelled In Space

Also, maneuverability, as I just don't see most of those sailing techniques working in a vacuum.

Solar sails don't, and have never been intended to, use "sailing techniques". In that sense "solar sail" is an unfortunate misnomer. Solar sail maneuvers typically take advantage of the fact that changing the sail orientation enable you to direct the resultant force from the solar radiation pressure either along or counter to the orbital velocity vector. Depending on which way you point the sail you either increase or decrease your orbit energy. Increases in orbit energy correspond to increases in orbit radius (or semi-major axis if in a non-circular orbit), while decreases in energy decrease the radius of the orbit. There's no "tacking" in the sense of ocean sailing.

Comment: Re:Its a good start (Score 4, Informative) 229

by GileadGreene (#32935984) Attached to: Ikaros Spacecraft Successfully Propelled In Space
The problem is that bleeding off energy with a solar sail isn't like just jumping onto a sunward elliptical orbit. You're likely to spiral in towards the sun, rather than zip around it. More importantly, a "slingshot" takes advantage of planetary motion relative to the sun to achieve a large trajectory change: a "slingshot" around the sun won't do anything except get you onto the outbound leg of the trajectory you're already on (i.e. it won't help you get further out from the sun than you were already going anyway). You'd probably be better off conserving the energy you already have, and using the sail to spiral out into a higher orbit.

Doctor Slams Hospital's "Please" Policy 572 Screenshot-sm

Posted by samzenpus
from the paging-doctor-manners dept.

Comment: Re:If I could do it, I would! (Score 1) 658

by GileadGreene (#31720410) Attached to: What the Top US Companies Pay In Taxes

Corporate CEOs are no friends of the free market...

Of course they're not. They wouldn't exist in an actual free market. Corporations themselves exist as the result of government interference in the free market, by way of laws that allow corporations to exist, to have legal rights that permit them to make transactions in the market, and to limit the liability of the owners. Corporate CEOs who lobby the government are simply trying to tweak the government's distortion of the regulated market even further in their favor.


Simpler "Hello World" Demonstrated In C 582

Posted by kdawson
from the non-obfuscated dept.

Comment: Re:So, does the Duct Tape Programmer... (Score 1) 551

by GileadGreene (#29551917) Attached to: The Duct Tape Programmer

Ruby and Python have only been "mainstream" for a few years, while static languages have been around since the ancient days.

Right. But Lisp, which is dynamically typed, has been around since the late 50s (second oldest high level language). And Smalltalk, which was a strong influence on Ruby, dates from the early 70s. Erlang has been around since the mid 80s. So "dynamic" languages have been around since the ancient days too. There's a place for both in the modern development environment. Horses for courses.

Some would argue that dynamic/duck + extra testing has the same effect with less cost than static + less testing.

Indeed. Others would argue that (good) static + more testing gives you the best of both worlds. This is a time-worn debate, and is unlikely to be resolved any time soon. Ultimately, the choice will come down to a combination of developer preference, and the cost/benefit/reliability issues associated with the specific domain you're working in. The biggest problem with debates like the static/dynamic one is that everyone seems to assume that the way software is developed in their specific application domain is suitable for every other application domain too. In practice, that's hardly ever true.

Comment: Re:Paying $500 for an OS that works, however... (Score 1) 1147

by GileadGreene (#27283329) Attached to: Ballmer Scorns Apple As a $500 Logo
It's more than just quality hardware and a good OS though. What you're getting when you buy an Apple product is a well-designed system. Aristotle said that "the whole is greater than the sum of its parts", and he's right in the sense that the quality of the whole depends on how the parts are combined and how they interact with each other. That's the bit that Ballmer doesn't seem to get. MS sells some of the parts. Apple sells the whole. Apple as a company may have some warts. It's products are not always perfect. But they, more than most companies, strive to develop good systems that do what the end-user needs, instead of just good parts that need to be fitted into a whole by the end-user. That's part of what makes Apple fans so loyal to the brand.

Comment: Concepts of Modern Mathematics (Score 1) 630

by GileadGreene (#26780507) Attached to: Mathematics Reading List For High School Students?

You might try Ian Stewart's Concepts of Modern Mathematics. Quoting from the end of the book:

The reader who has persevered this far must by now be a cultivator of mathematics, even if he was not at the start of the endeavour. He will therefore appreciate that, while it may be ancient and venerable, it is far from complete; that not all of it is dry; and that its reasoning has not always been either unambiguous or irrefutable - nor is it yet.

Which really captures what the book is about. It's an extremely accessible introduction to abstract algebra, topology, probability, and several other topics. It does a great job of presenting the overall structure of mathematics, and giving just enough of an idea of what's going on to make you want to learn more, without being dry, boring, or bogged down in details. I found it quite an inspiring book, and several friends that I lent it to found the same. Judging from the Amazon reviews, we weren't the only ones. All that, plus it's available as a low-cost Dover book :-)

Comment: Re:Barbra Streisand (Score 5, Informative) 1061

by GileadGreene (#26620343) Attached to: Global Warming Irreversible, NOAA Scientist Finds

That was not what they were teaching in schools 20 years ago. Oil was supposed to have run out about 1997 or 1998 and tin 1990ish.

Regardless of what you were taught in school 20 years ago, that's not what the actual Limits to Growth report said. There was a lot of bogus information propagated about the Limits to Growth report at the time it came out, largely by people who didn't like what it actually had to say. The reality is that the Limits to Growth report explored a number of different possible scenarios (varying assumptions such as the impact of technological change and of social policies), and found that most (but not all) scenarios seem to lead to some kind of "overshoot and collapse" in the mid to late 21st century. These were never meant to be precise predictions, but rather to provide some idea of the global system's behavioral tendencies. Interestingly, a recent study has found that the Limits to Growth "standard run" scenario tracks quite well with the actual observed behavior of the world over the last 30 years. As the abstract of that report says:

Contrary to popular belief, The Limits to Growth scenarios by the team of analysts from the Massachusetts Institute of Technology did not predict world collapse by the end of the 20th Century. This paper focuses on a comparison of recently collated historical data for 1970-2000 with scenarios presented in the Limits to Growth. The analysis shows that 30 years of historical data compares favorably with key features of a business-as-usual scenario called the "standard run" scenario, which results in collapse of the global system midway through the 21st Century. The data does not compare well with other scenarios involving comprehensive use of technology or stabilizing behaviour and policies.

Comment: Re:Republican? (Score 2, Insightful) 574

by GileadGreene (#26593031) Attached to: Senator Prods Microsoft On H-1B Visas After Layoff Plans

In a truly free market, government and Microsoft would not talk to each other at all. Microsoft would have to deal with its labor shortages in a different manner (perhaps hire some U.S. engineers w/o jobs, instead of willfully ignoring them).

In a truly free market, the government wouldn't apply any restrictions to the flow of goods or workers into and out of the country. There'd be no need for MS to beg for H1Bs because the government wouldn't be preventing workers from other countries entering the US in the first place. What you're describing as "truly free" is simply a different set of restrictions than the current ones.

Comment: Re:Why bother with space solar power? (Score 4, Informative) 275

by GileadGreene (#26187697) Attached to: Obama Transition Team Examining Space Solar Power
Actually, the sun does set in GEO. Just not for very long, and only at certain times of the year. Eclipse seasons for a geostationary satellite occur around the vernal and autumnal equinoxes. The seasons last around 40-50 days, with maximum sun-occultation duration of about 72 minutes. A discussion of the relevant orbit geometry can be found here.

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