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SpaceX Landing Attempt Video Released

Michael Woodhams Re:Wait a minute (248 comments)

If they couldn't dump to fuel tanks, and if dumping RP-1 overboard was a hazard, surely they'd just use a different fluid? If they're using RP-1 for the fins, I think that is a very strong indication that they're dumping to the fuel tanks.

about two weeks ago
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Chinese Spacecraft Enters Orbit Around the Moon

Michael Woodhams Re:Great to see (152 comments)

A minor nit-pick: I think you mean "chemical rocket".

Probably the most common rockets are liquid hydrogen/liquid oxygen. Neither are fossil fuels. Solid rockets could contain oil-derived plastics in their fuel, I don't know enough to say how often this is so. SpaceX uses kerosene/liquid oxygen which does use fossil fuel, although I expect it wouldn't be hard to substitute a suitable biofuel if they really wanted to.

about two weeks ago
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Chinese Spacecraft Enters Orbit Around the Moon

Michael Woodhams Re:Great to see (152 comments)

Since 1969 there have been people living on Earth who have visited another world. It would be a terrible failure of humanity if one day this was no longer true. I am not fond of the Chinese government, but if they send people to the moon, I'll be enthusiastically cheering them on.

about two weeks ago
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Ask Slashdot: Sounds We Don't Hear Any More?

Michael Woodhams Whooping cough (790 comments)

One of the best sounds to never hear.

about two weeks ago
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Researchers "Solve" Texas Hold'Em, Create Perfect Robotic Player

Michael Woodhams Re:Rock paper scissors (340 comments)

If game theory mathematicians say they've got a strategy which provably can't be beaten, I'll believe them until someone finds a flaw in their method. Mathematicians are notoriously picky about what constitutes a 'proof'. I'm sure they are quite aware of the possibility of an opponent which knows their strategy and adapts to it. (Note that in the rock paper scissors example, knowing the perfect strategy does not let you beat it.)

The article does not specify whether the strategy is deterministic or probabilistic. I expect the latter: sometimes its big lookup table will say "in this situation, raise 15% of the time, fold 85% of the time."

about three weeks ago
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Researchers "Solve" Texas Hold'Em, Create Perfect Robotic Player

Michael Woodhams Rock paper scissors (340 comments)

You can better understand what is going on by considering the much simpler game Rock paper scissors. 'Perfect' here basically means the strategy gives you the best possible worst case.

For RPS, the perfect strategy (using the term in the same sense as it is used for the poker bot) is to play completely randomly. There is no way to gain an edge over this strategy, no counter-strategy which will give you more than 50% chance of winning, even if you know your opponent's strategy. (In this case, there is also no strategy which will give you less than 50% chance of winning against the 'perfect' strategy.)

For the poker bot, there is no strategy that will give you greater than 50% chance of winning against it in a two player game. If you know its strategy perfectly (but of course you don't know its cards) the best you can do is to equal that 50% chance (which is what happens if it plays itself.) Unlike RPS, you can can lose to the perfect poker bot by playing poorly. Also, as noted in the article, the perfect poker bot always plays as if it were playing against perfect opposition. A good human player will fleece you faster then the perfect bot, because the human player will notice your peculiar imperfections and exploit them, choosing to play in a way which would be suboptimal against a perfect opponent, but superior against you.

about three weeks ago
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Why Open Source Matters For Sensitive Email

Michael Woodhams Trust (73 comments)

Sigh. Now somebody is going to bring up Ken Thompson's "Reflections on Trusting Trust" in 3... 2... oops, too late.

about a month and a half ago
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Ask Slashdot: Making a 'Wife Friendly' Gaming PC?

Michael Woodhams Re:And... (720 comments)

This whole discussion seems to have turned into an excuse for people to trot out their sex-stereotype preconceptions about the husband and wife's personalities and the nature of their relationship.

about 2 months ago
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Ask Slashdot: Making a 'Wife Friendly' Gaming PC?

Michael Woodhams Re:And... (720 comments)

What if his wife is also a gamer?* What if there is no other suitable room? What if they feel "the living room is the wife's domain" is twaddle? What if using the large screen TV for gaming is important to them?

* disliking a very loud gaming PC is not the same as disliking all gaming PCs.

about a month ago
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Ask Slashdot: Making a 'Wife Friendly' Gaming PC?

Michael Woodhams silentpcreview.com (720 comments)

silentpcreview.com is a web site dedicated to quiet and silent computing, with extensive reviews and forums. They have very recently posted a sample build of a quiet gaming PC.

You can take that as a base and adjust according to taste. (For example, I'm more obsessed by quiet and less by frames per second, so my gaming PC has a single GTX760Ti GPU.) If you have questions, take them to the forums.

about a month ago
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Scientists Develop "Paint" To Help Cool the Planet

Michael Woodhams Re:Some details from the paper (145 comments)

Emissivity and absorptivity are the same thing. One way to look at this is the time-reversibility of physics on a microscopic scale, another is that something that was really absorptive but not emissive or vice-versa would give you a really easy way to beat the 2nd law of thermodynamics. Emissivity can, however, vary with wavelength, which is the trick here.

about 2 months ago
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Scientists Develop "Paint" To Help Cool the Planet

Michael Woodhams Re:Some details from the paper (145 comments)

I think the second photograph in the article is the researchers reflected in their piece of film, so the answer is it is reflective like a mirror. I imagine you could put some translucent layer over it at the cost of some efficiency.

about 2 months ago
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Scientists Develop "Paint" To Help Cool the Planet

Michael Woodhams Re:Some details from the paper (145 comments)

Not really - the 40Wm^2 of cooling is only useful if it is in contact with something that can move that cold to where it is needed. (Hand-wavy explanation, really we are shifting heat to the film.) It also needs to see mostly sky, which windows usually don't.
You'd put it on your roof and run water behind it to shift the heat around.

about 2 months ago
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Scientists Develop "Paint" To Help Cool the Planet

Michael Woodhams Re:the law (145 comments)

Would you care to be more specific? My explanation is pop-science simplified, but I don't see an error in it.

More detailed explanation:
In the 8-13 micron (wavelength) window, atmospheric transmittance averages about 80% (estimated from a plot in the paper.) So the energy received is about 20% of what you'd get from a black body at atmospheric temperature (plus 80% of what you'd get from space, which is negligible in comparison.) So the brightness temperature at 8-13 microns is lower than ground level atmospheric temperature. How much lower depends on the average temperature of the atmosphere along the line of sight, and where 8-13 microns falls on the black body curve at that temperature (even this is oversimplifying) and I can't be bothered figuring that out. However, if we can reflect/insulate all energy except 8-13 micron radiation, then our thermal equilibrium temperature will be the brightness temperature at 8-13 microns to which we are exposed. This is, as noted, less than atmospheric temperature at ground level.

about 2 months ago
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Scientists Develop "Paint" To Help Cool the Planet

Michael Woodhams Re:the law (145 comments)

It is possible, because the environment is not in thermal equilibrium. In particular, the film 'sees' colder temperatures at some wavelengths than at others.

Did you not think before you posted that just maybe a bunch of scientists publishing in this area and the reviewers for one of the worlds top scientific journals might possibly have a better understanding of thermodynamics than you do?

about 2 months ago
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Scientists Develop "Paint" To Help Cool the Planet

Michael Woodhams Re:Hafnium in short supply? (145 comments)

The (paywalled) research paper states: "The use of HfO2 is, however, not essential, and can be replaced with titanium dioxide (TiO2), which is less expensive."

about 2 months ago
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Scientists Develop "Paint" To Help Cool the Planet

Michael Woodhams Some details from the paper (145 comments)

For those fortunate enough to have institutional access, the research paper is here.

Quickly picking some highlights:
The atmospheric transmission window is between 8 and 13 microns. They achieved 4.9C below ambient in direct sunlight at 850 watts per square metre. Cooling power was 40.1 watts per square metre. Emissivity (equivalently absorptivity) averages about 70% in the 8-13 micron window (estimated from a plot.)

Here's a quick back-of-the-envelope calculation
90% reflective white paint: absorbs 85W/m^2
97% reflective foil: absorbs 25.5W/m^2, an improvement over white paint of ~60W/m^2
This film: emits 40W/m^2, an improvement over simple foil of ~60W/m^2.
So in this scenario, the special film gives twice the benefit compared to just going for something simple and reflective. (The 90% for white paint is guess-work. The 97% for 'foil' is just matching the special film. Perhaps someone can update the calculations with better founded values.)

The summary title is highly misleading.

It is not paint, it is a manufactured film. It cools buildings, not planets. Yes, with enough you could cool the planet, but if you wanted to take that route, it would be much more cost effective to just use aluminium foil and use a marginally larger area of it (or, indeed, white paint.) Back in the real world, the way this invention cools the planet is by reducing electricity demand for air conditioning. (I saw another article about this in which one of the authors makes exactly this point.)

about 2 months ago

Submissions

Michael Woodhams hasn't submitted any stories.

Journals

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...si hoc legere nimium eruditionis habes...

Michael Woodhams Michael Woodhams writes  |  about three weeks ago

http://science.slashdot.org/comments.pl?sid=6635389&cid=48739641

http://www.latin-dictionary.org/Si_hoc_legere_scis_nimium_eruditionis_habes
http://www.archives.nd.edu/cgi-bin/wordz.pl?keyword=Si+hoc+legere+nimium+eruditionis+habes
If this to read too much learning you have.

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In principio erat Verbum.

Michael Woodhams Michael Woodhams writes  |  about a year ago

Here.

In the beginning was the word. Biblical, John 1:1. The full verse is
"In principio erat Verbum et Verbum erat apud Deum et Deus erat Verbum. "
"In the beginning was the Word, and the Word was with God, and the Word was God."

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Ceterum censeo Facebook esse delendam.

Michael Woodhams Michael Woodhams writes  |  about a year ago

Here.

Clearly derived from "Ceterum censeo Carthaginem esse delendam" which gets its own Wikipedia page.

This raises the question - how should Facebook be declined? My answer - just don't sign up for it.

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quiquid id est, timeo puellas et oscula dantes

Michael Woodhams Michael Woodhams writes  |  more than 2 years ago

Here.

By web search: "Whatever it is, I fear the girls, even when they kiss."

I can't find a source, but presumably a reference to
Vergil, Aeinid II.49
QUIDQUID ID EST, TIMEO DANAOS ET DONA FERENTES.
Whatever it is, I fear the Greeks, even bearing gifts.

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Vos nescitis quicquam...

Michael Woodhams Michael Woodhams writes  |  more than 2 years ago

vos nescitis quicquam, nec cogitatis quia expedit nobis ut unus moriatur homo pro populo et non tota gens pereat here.

Biblical, "You do not realize that it is better for you that one man die for the people than that the whole nation perish." John 11:50 (spoken by an antagonist.)

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Meus subcriptio est nocens Latin quoniam bardus populus reputo is sanus callidus

Michael Woodhams Michael Woodhams writes  |  more than 3 years ago

here.

It seems fractured, but I think
My Latin sig is criminal because I think stupid people are sane and clever.

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Carpe diem quam minimum credula postero.

Michael Woodhams Michael Woodhams writes  |  more than 4 years ago

here
Quote from Horace, the full version of more common "carpe diem".
Seize the day, trusting as little as possible in the next

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Mea navis aericumbens anguillis abundat

Michael Woodhams Michael Woodhams writes  |  more than 6 years ago

http://linux.slashdot.org/comments.pl?sid=564539&cid=23554467

My hovercraft is full of eels (again).

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Corruptissima re publica plurimae leges.

Michael Woodhams Michael Woodhams writes  |  more than 7 years ago

Here.

Translation by Google:
"The more corrupt the state is then the more numerous the laws." -- Tacitus, The Annals of Imperial Rome.

This may be a Libertarian/Conservative catch-phrase.

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Navicula hydraulica plena anguilarum est...

Michael Woodhams Michael Woodhams writes  |  more than 7 years ago

Navicula hydraulica plena anguilarum est. Omnes castelli tuus nostri sunt. Ed elli avea del cul fatto trombetta.

"Navicula hydraulica plena anguilarum est" = "the hovercraft is full of eels".
"Omnes castelli tuus nostri sunt" = "all your base are belong to us".
"Ed elli avea del cul fatto trombetta" = ?
"Words" doesn't recognize enough of this that I suspect it is not Latin.
Confirmed by websearch: It is Dante making a fart joke.

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Minutus cantorum, minutus balorum ...

Michael Woodhams Michael Woodhams writes  |  about 8 years ago

here
Minutus cantorum, minutus balorum, minutus carborata descendum pantorum

Translation found by google:
"A little song, a little dance, a little seltzer down your pants."

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Sic transit gloria mundi; non cum clamose, sed cum illatino.

Michael Woodhams Michael Woodhams writes  |  more than 8 years ago

here.

The first phrase is famous and googlable.
"Thus passes the glory of the world; not with applause, but with bad Latin."

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Armis Exposcere Pacem.

Michael Woodhams Michael Woodhams writes  |  more than 8 years ago

Two quotes in one .sig here

Translation by Google:
"Armis Exposcere Pacem" = "They demand peace through force of arms." (A similar sentiment to "Ubi solitudinem faciunt, pacem appellant".)

"Scientia non habet inimicum nisp ignorantem" = "Science has no enemies but the ignorant."

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