Wikipedia:Reference desk/Archives/Science/2014 April 1

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April 1

Wired can't figure out clean steel

Re http://www.wired.com/2014/03/clean-coal/ what is the best way to tell Charles C. Mann (twitter) that he forgot to look for [1] and [2] before going to press with "0 alternatives to coal in the industrial steel-making process," from China?

Also, does anyone have a current update for the graph at http://www.kobelco.co.jp/english/engineering/products/dri/dri01.html beyond 2005 please?

Furthermore could someone please start the simple:Sabatier reaction article from Sabatier reaction and look up the research from former Secretary of Energy Chu's company scrubbing CO2 from flue exaust? Thanks in advance. 114.84.141.82 (talk) 00:29, 1 April 2014 (UTC)

Direct reduced iron mentions [3], indicating 74 million metric tons of production in 2012. EllenCT (talk) 02:27, 1 April 2014 (UTC)

• This is not a forum for debating or criticizing living people. Please limit yourself at the reference desk to asking for references. Requests for article creation at Simple English belong at Simple English, not here. μηδείς (talk) 02:38, 1 April 2014 (UTC)

Are you implying that pointing out a factual error is an attack? EllenCT (talk) 02:56, 1 April 2014 (UTC)

This is not the place for "pointing out" things, for debate, or for criticizing living people. We don't publish our own criticisms of people and then invite others to correct them by publishing their twitter address. μηδείς (talk) 19:10, 1 April 2014 (UTC)

Here is the contact page for Wired magazine [4], you can contact them there. SemanticMantis (talk) 20:51, 1 April 2014 (UTC)

new course; Introductory to dice probability

Where can I offer to present course "Introductory to dice probability",300 or 400 class, 4 credit as new lecture on both physics and mathematics at Spring if Portland Oregon is not adequate or available?

I removed the e-mail address from this question's title to keep the e-mail address from getting spammed, as per the policy at the top of this page. Red Act (talk) 04:04, 1 April 2014 (UTC)

Well, you can offer any institution to teach a course for them. But in most cases that's not how teaching jobs work, so please be prepared to be ignored. Typically, colleges and universities post job offerings, detailing which courses they need instructors for. Job seekers apply, and the institution hires the candidate that seems best. You usually only get to make up your own course material after you've achieved some seniority in a department. In this case, you could look at mathjobs.org [[5]], and see if anyone is hiring staff to teach introductory discrete probability in your area. For example, here's a link to a recent syllabus from Portland State [6] SemanticMantis (talk) 21:02, 1 April 2014 (UTC)

Suggestion: Offer a free-lance course for casinos. You would want to include how to "detect a weighted die" in the material, so they can catch cheaters who swap dice on them. You might also offer the class to gamblers who want to know their odds. This seems like a community college offering, to me, and they might be a bit more flexible with their curriculum.

An online course might also work. It would take more work to set it up initially, but less work during each run of the class, and potentially it could be more profitable. StuRat (talk) 22:34, 1 April 2014 (UTC)

Temporal observation of Sirius apropos more-distant stars.

Greetings!

I am somewhat stumped by the proper motion of Sirius as it relates to the (much more distant) constellations with which we associate it. Right now, it appears among the stars of Canis Major, but—about 5,000 years ago—one would have seen it near the stars of Cancer.

I have two quick questions: First, will Sirius eventually "circle through the whole sky" (as the Sun does, every 25,776 years) passing through numerous constellations in the process. And, if so, then at what point, in the future, will our descendants see it again in Canis Major?

Thank You! Pine (talk) 04:47, 1 April 2014 (UTC)

Actually, Sirius hasn't moved much in 5000 years. According to our article, its proper motion is -1223 mas/year in declination and -546 mas/year in right ascension. At that rate, it would have moved -1.7 degrees in declination and -0.76 minutes in right ascension in the past 5000 years. Take a look at this star chart, where the big dot to the bottom right represents Sirius. You can see that a 1.7 degree shift is barely noticeable unless you're very familiar with the night sky. A modern star chart would be perfectly usable for someone living in ancient Mesopotamia, because very few stars have moved by a noticeable amount since that time.

As for whether Sirius will circle through the sky: it probably won't. If Sirius is moving in a straight line, its proper motion would drop towards zero and it would fade away to invisibility, just like a car driving on a straight road in front of you. Sirius is definitely not in orbit around the Sun, and there's no other reason to believe that Sirius would be circling the solar system. So in 10 million years or so, Sirius would be just another unremarkable star in the sky, visible only with binoculars. --

Bowlhover (talk) 05:56, 1 April 2014 (UTC)

Actually, the "big dot" on that pic is Procyon.

Silly me, of course it is! Here's another map, this time of the correct constellation: [7]. --Bowlhover (talk) 13:47, 2 April 2014 (UTC)

mas here probably means milli arc seconds, in case anyone was head-scratching. —Tamfang (talk) 05:27, 2 April 2014 (UTC)

And I believe the Sun visits each constellation (of the Zodiac) every year though the season will cycle on a larger scale. I don't think it will ever visit polar constellations. --DHeyward (talk) 12:17, 1 April 2014 (UTC)

What's that got to do with anything? —Tamfang (talk) 05:27, 2 April 2014 (UTC)

The sun doesn't actually "visit" any constellations. The constellations are in the background as we revolve around the sun. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:18, 2 April 2014 (UTC)

That all depends on your frame of reference. But I believe DHeyward was responding to the original poster's part about "as the Sun does, every 25,776 years". That is actually the period of the Earth's axial precession. In a frame of reference where the sun "visits the constellations", the effect of precession is that over time it visits different constellations within an equatorial band of the sky. For example, in different millennia we might find Orion or Canis Major on the zodiac instead of Gemini. --50.100.193.30 (talk) 21:38, 2 April 2014 (UTC)

No, the celestial equator moves, not the ecliptic. —Tamfang (talk) 07:40, 3 April 2014 (UTC)

Non-deuterium boosted nuclear device

http://m.koreaherald.com/view.php?ud=20140331001126

Assuming the Norks ain't got no deuterium, how much of a Boosted fission weapon can they get from just natural lithium? Hcobb (talk) 20:13, 1 April 2014 (UTC)

Lithium not only fissions to tritium and helium, but does it exothermically (as the Castle Bravo nuclear test demonstrated all too well) -- so the answer is, they can get quite a large boost from the lithium alone. But the more important question is, why would you assume the Norks ain't got no deuterium -- deuterium can be produced by a variety of well-established techniques, and AFAIK is not restricted, so they could get at least a small quantity quite easily. 24.5.122.13 (talk) 05:18, 2 April 2014 (UTC)

Perhaps they'll just build a Thunder Well and bring down the ISS. Hcobb (talk) 14:28, 2 April 2014 (UTC)

But can they hit such a small, rapidly moving target with one shot??? 24.5.122.13 (talk) 01:42, 3 April 2014 (UTC)

It's not maneuvering, so... maybe. OTOH, the thunderwell is a quite crude piece of technology. If you don't know the exact yield of the nuke, you get its muzzle v wrong. There is the added problem of drag at hypersonic velocities, not only in that it tends to stop a fast projectile quite violently; it's hard to calculate either. The first shot would probably miss.

Lithium, OTO²H, is quite easy to get. Modern batteries for cameras and laptops, anyone? - ¡Ouch! (^{hurt me} / _{more pain}) 07:24, 3 April 2014 (UTC)

Here's my script for "Mad Kim beyond Thunder Well": Boosted fission weapon under a concrete plug under a big pile of old cannon balls that have been covered in black carbon for heat resistance. So it's a shotgun blast against a target with little armor. Hcobb (talk) 16:42, 3 April 2014 (UTC)

Nice pop-cultural reference there...

Another source for the claim that the Thunderwell isn't suitable for anti-satellite duty (scroll down - it's near the end of the page), referencing the very same article.

Is it just me, or did WP change recently? I don't like the serif headlines one bit. - ¡Ouch! (^{hurt me} / _{more pain}) 07:51, 4 April 2014 (UTC)

Yes it did -- and no, I don't like it either. 24.5.122.13 (talk) 00:42, 5 April 2014 (UTC)