User talk:Pendragon5

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Your input is needed on the SOPA initiative[edit]

Hi Pendragon5,

You are receiving this message either because you expressed an opinion about the proposed SOPA blackout before full blackout and soft blackout were adequately differentiated, or because you expressed general support without specifying a preference. Please ensure that your voice is heard by clarifying your position accordingly.

Thank you.

Message delivered as per request on ANI. -- The Helpful Bot 16:39, 14 January 2012 (UTC)

o = stephan law constant.

Orbital period in seconds[edit]

Hi Pendragon5. Note that Mmeijeri quite correctly reverted your good faith edit to orbital period. A formula such as T = 2\pi\sqrt{a^3/GM} yields a result of time, but not in any one particular unit. Big G is often given in units which include time in seconds, but that is not always the case, and more importantly, that need not be the case, and it is the choice of units of the constant which determine the units of the result. Even if, for practical purposes, G is never presented in units which don't include time in seconds, it is still incorrect to say that the formula yields results in seconds. It may do so in practice, but that would be an "accident of usage" which is not inherent in the formula. I understand that your edit was motivated by Jayron32's "you get the orbital period in seconds", but that was because he provided G in m3 kg-1 s-2.

Given that the formula above holds for the orbit of the earth, it would be easy (and perhaps useful) to solve for G in terms of years, astronomical units, and solar masses. What do you get? (Also, you may be interested in our Units conversion by factor-label and Dimensional analysis articles.) Thanks for trying to clarify our article; just that particular edit wasn't correct. -- ToE 00:38, 21 February 2012 (UTC)

So, have you attempted to compute G as I described above? If it is not quick and easy to do, then it is something that you need to practice and which might teach you something new. Let me know if the idea is not clear, and I will spell out the steps more clearly. -- ToE 23:20, 27 February 2012 (UTC)

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Nomad planets[edit]

Did you see this story, reporting on a paper which estimates the number of free-floating or rouge planets (ranging down to 10^-8 solar masses -- the mass of Pluto), unbound to any host star. They suggest that there may be up to 100,000 times as many such nomad planets as there are main-sequence stars. The abstract is here with a link to the paper here. What made me think of you wasn't the current estimate (as interesting as it is), but the fist paragraph in the paper's introduction, which contains: "Searches for exoplanets from radial velocities find that ...", which reminded me of your questions 16. Our article on this is Methods of detecting extrasolar planets#Radial velocity. -- ToE 00:45, 26 February 2012 (UTC)


Regarding the image you posted for number 27, owning the worksheet is not the same as owning the copyright. Just as you don't own the right to publish a book simply because you purchased a copy. Unless you wrote the worksheet yourself or received a transfer of copyright ownership from the author/publisher, you actually have no legal right to post it here, and certainly no right to release it under the creative commons license. It would be best if you G7'd the image once you're satisfied with the responses. This is purely for informative purposes. I actually don't care. Cheers. Someguy1221 (talk) 01:00, 1 March 2012 (UTC)

Wikipedia:Criteria for speedy deletion#G7. Basically, you would just throw {{db-g7}} on the top of the page, and in a short time it will disappear. Someguy1221 (talk) 03:23, 1 March 2012 (UTC)
Note that Wikimedia Commons, where you uploaded them, has even stricter copyright requirements, and unlike Wikipedia does not even allow "fair use" images. G7 still applies to Commons, as described at Commons:COM:Criteria for speedy deletion. To save work, both for yourself and the deleting admin, you may wish to tag one of your recent uploads with {{Db-g7|Please see talk page for list of additional files.}} after adding a note on that file's talk page listing all the other files you would like to have removed. The admin should see this while checking the file's final diff. -- ToE 14:42, 1 March 2012 (UTC)

International Astronomy Olympiad[edit]

I'm sorry to hear that you did not rank as well as you had hoped. I do have some advice for your preparation toward next year's exam, ... if you are interested in hearing it.

First, can you confirm my understanding that you will be taking High School Physics this coming year, and High School Chemistry the following, your senior year. Is this the normal order at your school, or are you opting to take them in reverse order?

Also, if you could answer this astronomy question, and explain how you went about doing so, it would help me understand where you are.

Q1: Star A and Star B are of the same brightness as observed from Earth. It is determined that Star A is a nearby dwarf star of absolute magnitude 12.0. What is the absolute magnitude of Star B, given that it is 1,000 times more distant than Star A?

QM1a: Were you able to do this problem without looking up any formula? If not, what did you look up?

QM1b: Were you able to do the calculate for this problem in your head? If not, what did your calculation look like?

QM1c: Now that you have done this problem, would you expect to be able to do it in your head, without looking up any formula, were you to run across it in a year's time?

-- ToE 17:19, 9 March 2012 (UTC) (I'm still traveling for another couple of days, but we are picking up this signal from an island that must be about 20 miles away, so I thought I'd give it a try.)

(Pendragon5's response is here.)
Regarding Chemistry vs. Physics, your decision sounds like a good one, as the problems you will do in Physics will be much closer to the IAO problems than the ones you will do in Chemistry. My only concern would be if that order was an unusual choice, as then some mathematical concepts may be introduced in the Chemistry class which the Physics students would be expected to have already mastered. Were that the case, you should speak to a Physics and Chemistry instructor to find out how you should prepare for taking them out of order.
Regarding the -3.0 absolute magnitude question, good job. To do that problem you (presumably) applied two concepts which you were asking about just last week. You said earlier that you appreciate frankness, so I will be frank now. While I am sorry that you did not perform up to your expectations, I was not at all suprised to hear so. I certainly don't think that you are "dumb" or "stupid", as you frustratingly expressed when working Q16, but clearly you were not familliar with the material and were not experienced in the type of questions they asked, and while a couple of weeks of cramming might have helped, it won't bring you up to a competitive level.
You will presumably do better next year, what with your Physics class and another year of mathematical sophiatication (BTW, what math classes do you take your Junior and Senior year?), but if your astronomy & astrophysics specific preparation consists of just another month of cramming, then you are not going to do as well as you wish. Even if you do manage to do well enough in your state competition, at the national level you may be pitted against considerably better prepared participants. Students from northern Illinois, for example, will have attended the 24 week Astro-Science Workshop at the Adler Planetarium. This program invites select High School students (typically Sophomores and Juniors) from the region to attend Saturday classes at the planetarium where each week a different researcher would give a half-day presentation on their work. When I attended (they call it the "Astrophysics Workshop" back then), the director of the planetarium was influential enough (and had an education budget large enough) that quite a few well known active researchers flew up to Chicago just to make their worshop presentation. I particularly recall a researcher from JPL who flew in with the latest Viking lander imagery and analysis which had not yet been released to the general public. At the time I attended there was not an emphasis on preparing for something like the IAO (which didn't yet exist), but I wouldn't be surprised if such a side program is now in place.
So what are you going to do over the next year to be in a position to compete against the top students from those who have had that kind of exposure to the field? (I am not trying to discourage you here, but am hoping to give you a realistic view of what you are up against. I do have a suggestion of how you could be quite competitive next year, but want to hear of your plans first.) -- ToE 00:32, 12 March 2012 (UTC)

The exercise above[edit]

Regarding the exercise above, anyone familiar with the material, and certainly anyone who expects to be competitive at the IAO, should immediately think, "If two stars appear equally bright from the earth, and one is 1,000 times more distant, then the more distant one must be (1,000)^2 = 1,000,000 times more intense." Yes, this is an application of the inverse-square law, but it is not a matter of remembering some memorized formula. If you were told that one runner was traveling at exactly half the speed of another runner, would you have to look up the formula "distance_traveled = speed * time" before you realize that the slower runner will take twice as long to complete the course? I'd hope not! Likewise, you needn't memorize the inverse-square law to understand and use it. You just need to understand that as a consequence of the three (spatial) dimensional nature of the universe in which we live, intensity will fall with the square of the distance.

Working the second half of the problem isn't quite as intuitively obvious because the magnitude scale is a hokey, man-made construct, but it is easy enough to do if you understand how the magnitude scale was set up. An oversimplified history of magnitude is that the visible stars were originally categorized by apparent brightness into six magnitudes, with the brightest ones called magnitude one and the dimmest ones visible without a telescope called magnitude six. It was also observed that the brightest stars were about 100 times more intense than the dimmest visible ones. Thus a change of five magnitudes (from one to six) represented a factor of 100 change in intensity. That "five magnitude change = factor of 100 intensity change" was adopted as the definition of a refined system, with magnitude one stars being those which were exactly 100 times brighter than the dimmest visible (magnitude six) ones. This led to the problem that fifteen stars (from the thousands visible anywhere in the sky) were brighter than this newly defined "magnitude one". Vega was close to the 0 mark, and at one time the scale was defined placing it exactly at magnitude 0.0, but further refinement of the system has given Vega a magnitude of +0.03. That leaves the four stars which appear brighter than Vega with a negative magnitude, ranging from Sirius at -1.47 to Alpha Centauri A at -0.01. The improtant part to remember from all this is that brighter stars have less positive (or more negative) values of magnitude, and that a change of magnitude of 5.0 represents a factor of 100 change in intensity. (That latter point makes it a logarithmic scale, though not as mathematically a natural one as what we use with sound, where a change of 1.0 bel represents a factor of 10 change in intensity. In practice, we find if more useful to work with tenths of bels, known as decibels or dB, just as with magnitude we find it useful to define the system with a different scale such that a change of 5.0 magnitudes representing a factor of 100 change in intensity.)

So, back to our problem were one star is 1,000,000 times brighter, in absolute terms, than another. How many 100 does it take to make 1,000,000 (multiplicatively)? Well, 1,000,000 = 100 * 100 * 100, and each of those "factor of 100" represents a change of 5.0 magnitudes, for a total change of 15.0 magnitudes. The dimmer star was of magnitude 12.0, so the brighter star is of magnitude 12.0 - 15.0 = -3.0. (Remember, brighter is more negative.)

That all took a while to read, but think how short it is to implement. "Of two stars with equal apparent brightness, the one 1,000 times more distant is shining (1,000)^2 = 1,000,000 = 100 * 100 * 100 time more brightly in absolute terms, and thus has an absolute magnitude 3 * 5.0 = 15.0 brighter than 12.0, or 12.0 - 15.0 = -3.0." A year from now, if you have learned the material well enough, you should be able to calculate an easy question like this as quickly as you can read the sentence above.

That increased speed and confidence buys you some concrete benefits during the test, but it is the more abstract benefits that are the important ones. The level of true understanding necessary to work the problem this way will not just give you a faster, more reliable route to the correct answer, but it will also let you better understand what is being asked in more complicated questions where the inverse-square law or magnitudes appear, and, most important of all, it will have allowed you to better learn more advance concepts where they play a supporting role.-- ToE 01:36, 14 March 2012 (UTC)

WOW nice nice! That was probably 3 times faster and a lot easier way to do it than the formula way. This is absolutely going to be an advantage for someone who can come up with the faster way. You just made me realize something important. While memorizing formulas is a good thing but not the best because chances are i will forget some of them. To totally consider as understand something one must easily come up with a formula to solve a related problem. Like my math teacher, whenever is possible he always teach us the way to solve some problems without memorize formulas. Technically we are solving the problems with our own recreation formula without realizing we are using the formula. It's the best way because if i can recreate a formula and do it a problem by myself, chances are i won't ever forget it. So i think i know which direction to head now. I need to somehow master the materials to solve the problems with the fastest, most efficient way without rely too much on formulas. Thanks!Pendragon5 (talk) 02:33, 14 March 2012 (UTC)
I'm traveling for the next several days (up to a week, depending on the wind) and don't expect any connectivity. -- ToE 00:12, 16 March 2012 (UTC)


I replied to your sensible comment at Talk:Ngo Bao Chau; among the various RMs to restore these moves it's refreshing to see someone come straight and direct to the nub of the issue. It's unfortunate however that the same consensus does not exist for Vietnamese bios as for Slovaks Talk:Dominik Halmosi (why this is I'm not sure). Anyway, thanks again for your comment. In ictu oculi (talk) 03:00, 15 September 2012 (UTC)

Hi, thanks for the message. I was there in the 1990s for work, still keep contact there. As regards the accurate spelling, I still consider it correct, just as correct as Talk:Dominik Halmosi, but also use of Vietnamese was the majority wish of en.wp RM participants and of recent RfC participants. But it has to be recognised that there is a thinner support than for, eg, Slovak names, as I said above. As regards Vietnamese_names#Synonyms_distinguished_by_vowel_or_tones, new examples would be interesting. In ictu oculi (talk) 01:03, 16 March 2013 (UTC)
Vietnamese diacritics RfC results 23-10 (or 23-16 including canvassed votes)............ however it is mainly in article titles which really are Vietnamese such as Nam Quoc Son Ha, Viet Nam vong quoc su, Bau cua ca cop, Goi cuon, Bun rieu where removal of accents is particularly jarring. In ictu oculi (talk) 01:07, 16 March 2013 (UTC)