A Sunday at the Parco di Valcorba March 31, 2006
Posted by dorigo in personal, travel.2 comments
Last Sunday I took my family to a zoological garden called "Parco di Valcorba". It is located next to Rovigo, less than an hour by car from Venice.
The day was sunny and warm, and we had a great time. Filippo learned how to use the map of the place, and Ilaria was very happy to see so many nice animals.
Here is the one tiger they have - they keep it in a suitably large enclosure, although the animal did not look too happy there.
I took this picture and the following ones with a Nikon D70 and a 70-300 mm zoom lens.
Splitting hairs and stars March 30, 2006
Posted by dorigo in astronomy, personal, physics, science.add a comment
Building a telescope is one of those things you can do with a huge variety of levels of accuracy. As yesterday's post shows, one can build a telescope that would have made Galileo drool in five minutes, given enough spare parts. But the amount of ingenuity and precision that is required if the maker strives for perfection, is apparently bottomless.
As I delve in the documentation of simulations of thermoconvective motion of the air in a telescope tube, of axial stresses to the mirror surface due to edge supports, and of thermal hysteresis of large thick mirrors, in the hope of determining what is best for the 16" dobsonian scope I am having custom-built by Romano Zen (shown on the left at the optical bench with another 16" mirror he is testing - not mine), I feel kind of helpless…
But I am not that kind of guy who throws his hands up and forgets about perfection. I am a perfectionist, in truth, and if stimulated enough (I am more lazy than perfectionist at times) I will do what is needed to ensure the final product is as good as can be.
One of the things I am studying right now is the thermal equilibrium of the mirror with the surroundings. Imagine the usual picture: the telescope is carried to a dark site - typically cold, since mountainous - from its storage (my home), then is assembled, and then used. The outside temperature is initially lower than that of the mirror, which weighs 30 pounds and takes a long time to acclimate. Fortunately, Zen's mirrors are made with 1.6" thick glass, which is not too thick for a 16" diameter, and so take less time to radiate their heat away. Also, Zen's dobsonian scopes have an open bottom, which eases heat exchange with the ambient. Detailed simulation of the heat transfer from mirror to air have been made, and the time constants for a given temperature gradient are known.
What do we care about the mirror temperature ? We do, because the parabolic mirror surface shrinks while the mirror cools down, and that causes variations in the surface which spoil the precise focusing and introduces astigmatism in the image. At high powers one does not see pinpoint stars but sizable balls of light if the mirror has not perfectly cooled down.
So, heat transfer by conduction is important, but it has been solved.
However, how about IR radiation ?
A mirror exposed to the outer sky exchanges IR radiation with it, according to Stephan-Boltzmann's law. The high reflectivity of the mirror implies that the emissivity is low, but not negligible. If one makes some assumptions (with which I will not bore the reader here), one finds a radiated power of 1.5 Watts from the mirror's surface. The bottom also exchanges IR radiation with the environment, and the -say- 20 degree difference will cause more power loss.
Here comes the interesting point: if the mirror's back is painted in black, one gets 3 more watts of cooling, but if the glass is kept transparent one gets way less than that. Also, the 1.5 W from the front are only achieved if the mirror is left "looking" at the whole sky - i.e., with no light shroud around the truss poles of the mount, and pointed at the zenith.
4.5 watts are not negligible, and they should help sizably in acquiring thermal equilibrium faster.
I think I will ask Romano to paint the mirror's back in black…
This is splitting hairs, but the aim is actually to split (double) stars! The highest magnification powers are only allowed if everything is perfect - thermically, optically, and atmospherically. And I know people with large dobsonians who have to wait three to five hours before using the scope on planets during cold nights. I hope I won't need to wait that long!
How to build a telescope in five minutes March 29, 2006
Posted by dorigo in astronomy, games, news, science.add a comment
Amazing…
My office is across the corridor from our lab, where colleagues who study irradiated silicon detectors and radiation damage. It is not a real lab, rather a big room with some equipment - a big microscope for checking electronic circuits, an oven, and little more. But they do happen to have some optics pieces.
Today's eclipse stimulated a general interest in building a telescope to observe the sun by projecting its image from an ocular. Riccardo and Serena dug amidst piles of material to find an achromatic doublet, a wide selection of optical tubes of various sizes and threads, a precision-crafted diaphragm, and several connection rings. We set out to build the telescope by trial and error, and in a few minutes, as kids playing with lego, produced the tube assembly. An ocular was missing: we borrowed one of the extremely expensive oculars of the Leitz microscope (which is worth some tens of thousands euros by itself), and fit it to the tube with suitable joints. As a focuser we used two pieces of tubing that could be screwed into each other.
The final assembly is not only functional, but quite esthetic to look at!! It is a 40mm F/5 achromatic refractor, with a black finish. We already tested it on the sun and it produced a crisp image once the diaphragm was adjusted.
Unbelievable how easily we were able to put it together… As Riccardo put it "it is incredible how much you can accomplish with patience, ingenuity, and some 1,000's of euros worth of equipment".
We set the scope on a cardboard box and projected the sun's image on a sheet of paper. At that point I realized we made a mistake: "Guys, we fell short of finishing the job. Is there enough stuff to put together an equatorial mount around here ?"
Hmmm, maybe next time.
A Live feed for today’s total solar eclipse March 29, 2006
Posted by dorigo in astronomy, internet, news, science, travel.add a comment
Here it comes, March 29th. Mariarosa's birthday, and I'd rather be in Turkey…
Peter Woit is now in Africa, enjoying the views. And I am stuck in my office, trying to debug a root macro. Life sucks!
Anyway, I found a site that promises to broadcast a live feed of the central phases of today's eclipse. You can visit it at the following link:
http://www.exploratorium.edu/eclipse/2006/index.html
No guarantees it will work… But they look competent. Let's hope for the best.
30 pages for a proceedings paper ?!?! March 28, 2006
Posted by dorigo in books, news, personal, physics, science.2 comments
I just got mail from the organizers of CORFU 2005 (a Particle Physics conference and a school, held last September in Corfu Island, Greece - see here for details: http://qd.typepad.com/6/2005/09/nice_dinner_in_.html) that I have to write the proceedings of my summary talk by the end of May.
Oh well, that is two months away… It would typically leave me eight weeks of unconcern and one freaking week in the end.
But this time it is, unfortunately, different: they asked me for a 30 (or more!) page manuscript. What the heck am I supposed to write in 30-something pages about "High Pt Physics: from the Tevatron to the LHC" ??
Hmmm. Actually, there is indeed a lot to write about.
Hruumph. Snort…. I can do it. But it takes time… And I am soooooo lazy.
Any ghost writers out there ?
My prime minister likes to fake sexual acts with strangers March 27, 2006
Posted by dorigo in games, humor, news, politics.2 comments
Let's play a game. I know there are people from around the world reading this blog, so I challenge anybody to demonstrate THEIR prime minister acts more weird than mine.
http://www.break.com/index/primeminister.html
How's that for a starting bid ?
Acting against the pitiful situation of basic research in Italy March 27, 2006
Posted by dorigo in internet, news, physics, politics, science.5 comments
I promised I'd translate in English (as well as I can without looking into a vocabulary) the former post. Here is my attempt.
Press release: "Chat and Badges" in italian Research, the scientific community manifests for a serious change after gloomy and hard years (italian scientists for Italy of Knowledge).
Do italians know that during the last five years the financing of research institutes has been reduced by more than 20%?
Do italians know that during the same period a stop of 4 (four!) years in hiring new personnel in these institutes effectively shut doors to young researchers ? Do they know tha none among the presidents (of political appointment) has ever raised any official objection on this issue to the competent ministers ?
Do italians know that CNR (consiglio nazionale delle ricerche, or national council of research) and INAF (istituto nazionale di astrofisica, or national astrophysics institute) have designed organizational structures who resemble more military camps than modern businesses (both, obviously, models unsuited to research) ?
Italians do not know any of that becaus during these years we were spectators to public declarations and long interviews by minister Moratti and by the presidents of the institutes, installed by her, where the new course of italian research was plauded. The president of CNR distributes plainly insufficient ordinary funds to the research institutes, goes to radio or TV broadcasters and paints in bright colors the news of the new CNR. Chat, lots of chat, in fact. But in the meantime, the badges of presidents- commissaries start working and implement the spoils system, destructuring the research network, increasing bureaucracy, substituting projects with outsourcing, claiming powers and functions, sell hard-earned properties.
The scientific community, who in this Country has always worked in difficult situations, assisted incredulous to the show of these years, and now has had enough (we even tried, not only us from the Observatory, but in many different venues, to open a dialogue and reaffirm principles, but nevertheless without any real result).
In the face of the sudden acceleration of changes (in particular in CNR) to secure a few seats and a devastating restructuring of the research network (based not on evaluations of the scientific productivity - which is in any case eccellent given the human and economic resources available - but on techno-bureaucratic values) this community decided to come out and protest to declare their objection to this method of chat and badge.
One can argue that, close to political elections, this act might be interpreted as a political one, an instrumental choice. It is exactly what the scientific community intends to do! If our job has not been sufficient, if the credibility of a community vexed and nevertheless productive cannot leave a mark, we will use as an instrument public manifestations. Public externations to express plainly, in dignity but with determination, our point of view, negated during the last years of long interview by the presidents-commissaries of "everything is going better". A political act. And even a definitive choice: in favor of research!
Speaking clear and loud to politics to repel methods and procedures who have nothing to do with the management of research and science. Declaring to who is going to govern the country after April 10th that research has to be put in the conditions to express their huge potentials by respecting some essential principles such as scientific autonomy, an adeguate financing, the integration of young generations. And whoever wins we will have to affirm immediately and without hesitations this change of strategy: send home all sheriffs, and less chat!
The opposite of chat means to keep in the right value the relationship between research and citziens: to seriously broadcast scientific culture, to make transparent the economic balance of institutes and the research made. And more than everything, stop telling the contrary of what is actually done.
The scientific community must contribute to Italy of knowledge. For that reason too, it will manifest on March 30th in Rome in front of the CNR in Piazzale Aldo Moro, at 10.30 AM. From all around Italy researchers, scientists, technicians are getting ready to be present to this happening.
Osservatorio sulla Ricerca (www.osservatorio-ricerca.it)
Battling the policy on research funding of the Berlusconi government March 27, 2006
Posted by dorigo in internet, news, physics, politics, science.add a comment
Here is the text of the italian Osservatorio sulla Ricerca about a manifestation to be held on March 30th. I will translate into English as soon as I can, for now it is in Italian.
COMUNICATO STAMPA: "Chiacchiere e distintivi" nella ricerca italiana, la
comunità scientifica manifesta per un cambiamento serio dopo anni bui e
difficili (gli scienziati italiani per l¹ITALIA DELLA CONOSCENZA)
E¹ al corrente l¹opinione pubblica che negli ultimi 5 anni il finanziamento
agli enti di ricerca si è ridotto di una frazione spropositata: oltre il
20%?
E¹ al corrente che nello stesso periodo un blocco di 4 (QUATTRO!!) anni
nelle assunzioni in questi enti ha sbarrato le porte ai giovani? Sa che
nessuno tra i presidenti (di nomina politica) ha mai posto su quest¹ultimo
punto alcuna obiezione ufficiale ai ministri competenti?
Sa l¹opinione pubblica che le riforme del CNR (Consiglio Nazionale delle
Ricerche) o dell¹INAF (Istituto Nazionale di AstroFisica) hanno disegnato
articolazioni organizzative, gerarchiche e accentratrici, somiglianti più
a caserme militari che a moderne aziende (ovviamente, entrambi modelli
inadeguati per la ricerca)?
L¹opinione pubblica non sa tutto questo perché in questi anni abbiamo
assistito a pubbliche dichiarazioni e a lunghe interviste del ministro
Moratti e dei presidenti degli enti da lei nominati in cui si esaltavano le
nuove sorti della ricerca italiana. Il presidente del CNR mentre
distribuisce fondi ordinari del tutto insufficienti agli istituti di
ricerca, va alla radio o in tv a magnificare le mirabolanti novità del nuovo
CNR. Chiacchiere, molte chiacchiere per l¹appunto.
Ma contemporaneamente i distintivi dei presidenti-commissari entrano in
azione e implementano lo spoil system, destrutturano la rete di ricerca,
aumentano la burocrazia, sostituiscono progetti con ³commesse², accentrano
funzioni e poteri, cartolarizzano le proprietà con fatica acquisite nel
tempo.
La comunità scientifica che in questo Paese ha sempre lavorato in situazioni
difficili ha assistito incredula allo show di questi anni e oggi proprio non
ne può più (abbiamo anche provato non solo noi come Osservatorio, ma in
tanti soggetti, comitati spontanei, associazioni e sindacati- ad aprire un
dialogo e ad affermare principi ma, nonostante l¹accordo della base, senza
alcun reale risultato).
Di fronte all¹improvvisa accelerazione di trasformazioni (in particolare nel
CNR) per mettere al sicuro un po¹ di nomine e una devastante
ristrutturazione della rete di ricerca (basata non su valutazioni di
produttività scientifica che pure è di indubbio rilievo e anzi
d¹eccellenza viste le risorse umane ed economiche- ma su valori
tecno-burocratici) questa comunità ha deciso di scendere in piazza e di
dichiarare la propria contrarietà a questo metodo di chiacchiere e
distintivo.
Si potrà dire che a pochi giorni dalle elezioni politiche, questo atto
potrebbe essere interpretato come un atto politico, una scelta di campo
strumentale. E¹ proprio quanto la comunità scientifica intende fare!
Se il nostro lavoro non è stato sufficiente, se la credibilità di una
comunità vessata e pur tuttavia produttiva non riesce a contare, useremo
come strumento la piazza. La piazza per esprimere con serietà, dignità ma
anche determinazione il nostro punto di vista, negato in questi anni di
lunghe interviste ai presidenti-commissari-sceriffi del ³tutto va meglio².
Un atto politico. E anche una scelta di campo definitiva: a favore della
ricerca!
Parlare chiaro e forte alla politica per respingere metodi e procedure che
nulla hanno a che fare con il governo della ricerca e della scienza.
Dichiarare a chi governerà dopo il 10 di aprile che la ricerca deve essere
messa nelle condizioni di esprimere le sue enormi potenzialità rispettando
alcuni principi essenziali come l¹autonomia scientifica, un finanziamento
adeguato, l¹integrazione delle giovani generazioni. E che chiunque vinca
bisognerà affermare immediatamente e senza cedimenti questo cambio di
strategia: via tutti gli sceriffi e meno chiacchiere!
Il contrario delle chiacchiere significa tenere nel giusto conto i rapporti
tra ricerca e cittadini: diffondere seriamente cultura scientifica, rendere
trasparenti i bilanci degli enti e le ricerche condotte. E soprattutto non
raccontare il contrario di quanto si fa realmente.
La comunità scientifica ha il dovere di contribuire all¹Italia della
conoscenza. Anche per questo manifesterà il prossimo
30 marzo a Roma sotto il CNR di piazzale Aldo Moro alle 10.30.
Da tutta Italia si stanno organizzando ricercatori, scienziati, operatori di
ricerca per essere presenti a questa iniziativa.
Osservatorio sulla Ricerca (www.osservatorio-ricerca.it)
Family arguments and excel spreadsheets March 26, 2006
Posted by dorigo in computers, personal.1 comment so far
Tonight I used an excel spreadsheet to prove my wife she was wrong…
She has been concerned with Ilaria's weight for a while, and ventured to say that Filippo at her age was 39 pounds (Ilaria is 3 years old). Of course, the gross overestimate of the problem is typical of Mariarosa's need of reassurance, which she often expresses through quoting falsified data. Too bad she lives with a scientist, who cannot manage to be pious enough to forgive the wrong claims and simply give the reassurance she is asking for.
So I said 39 lb really sounded too much to me at 3 years of age - Filippo has always been lean-, and walked to my laptop, from which I fished out the excel data file. It showed that Filippo was 36 pounds at 4 years of age.
Mariarosa tried to question the data, and claimed she remembered very well of having weighed Filippo while on vacation in Croatia. I have the highest consideration for Mariarosa's memory, but even higher is my trust on the data I put in my files. Indeed, we have a very precise scaler at home, and if three separate determinations (in three different days)say 36 pounds, the weight has to be 36+-0.2 lb, period.
So my wife had to acknowledge Ilaria's weight (31 lb) is not so outrageously low for her age. A relief for me, but I feel bad for having used my computer against her… However, I think I sort of achieved my aim of reducing her worries about Ilaria's weight.
While I was writing this post, Mariarosa came by and read what I was writing… She actually points out she is not an apprehensive mother! I think she is right in a way - some of her friends typically keep under siege the pediatrician's office day after day. Maybe the right evaluation is that she is a mildly apprehensive mother, with friends who are plain nuts!
