The impression I was given was that since glass was an extraordinarily slow flowing liquid, if you wait long enough it will become a puddle of glass. Along the way the glass would slowly ‘melt’ somewhat like ice, however, it is so slow moving the process would be slightly different as nothing would ever ‘break off’ just continue to slowly melt. It has been over 20 years, but as I recall he said something like a million years would be long enough for this process to happen (keep in mind not only are we dealing with my possibly erroneous memory, but also the state of the art at the time. However the man telling me this was a superbly educated, highly awarded chemistry professor, so I doubt that his opinion as offered at the time was against the prevailing research.)
I thought that glass gradually crystalized over long periods of time. I’d heard that antique glass is extraordinarily fragile for this reason.
That’s what I thought, but I’m just confused a bit. So, does glass actually flow over that sort of time span? I was taught the whole “glass is a super-cooled liquid” thing, too, but now that we recognize it as as amorphous solid, would we expect that it would still “flow” over a million years?
The point of putting it on the moon was to get it into vacuum and remove as many of the environmental effects that cause glass to be destroyed before the glass would have time to flow. To really have it work, you would be better off building a sealed container, evacuated of all atmosphere to the limits of your technology, as highly insulated against changes in temperature and physical damage as possible and probably locate it somewhere with higher gravity, like the earth. I put it on the moon for romantic reasons, the image of a beautiful piece of glass artwork that you return to in a million years and it has become a plain puddle of glass (probably perfectly round based on the slow flow rate) is very esthetically pleasing to me.
But the pubic hair was to be left alone? Or did she let the girls draw their own conclusion?
I remember my eighth grade teacher, at the height of the cold war, saying that she wasn’t worried about nuclear war. The early, puny bombs dropped on Hiroshima and Nagasaki were so heavy the planes carrying them could barely take off, she said. With bombs ever so more powerful, how would they ever be delivered?
I imagined the President picking up the red phone to the Air Force and saying, “Those Russkies have gone too far this time. Smite them.” An hour later an apologetic general calls back saying that unfortunately every one of their bombers had crashed.
I started to point this out when a rare moment of diplomacy intervened: She was better off blissfully unaware I concluded. The incident inoculated me with the skeptic bug, though and it persists today.
Thomas Harriot (also a very important, but much neglected figure in the history of mathematics).
However, Galileo’s telescope was better, his observations and drawings were better, he drew more significant conclusions, and, most important of all, he bothered to publish!
All true, but this rather under plays Galileo’s importance to physics. In essence it was Galileo who transformed what began as a technical (albeit radical) reform in astronomy into a true scientific revolution. It was Galileo who realized that in order to reconcile the Copernican hypothesis of a moving Earth with common observational fact (such as the fact that things do not move to the west as they fall) it would be necessary to completely reform the science of mechanics, and he made a pretty good start on that reform, laying its conceptual foundations and starting to fill in some of the details. He worked out a mathematical law of fall, based on careful, quantitative experiment (itself a pretty new idea), and first developed such basic mechanical concepts as acceleration, average speed, and, most important, inertia. The last foreshadows Newton’s first law of motion, and constitutes the crucial, radical break with Aristotelian conceptions of motion.
Newton actually stole the First Law directly from Descartes, who had adapted it from Galileo. However, Galileo had conceived of natural, unforced motion as circular rather than rectilinear as Descartes and Newton did. Nevertheless, Newton was clearly aware of the huge debt he owed to Galileo. Without Galileo, no Newton, and no modern science.
Galileo was a very great scientist. However, he was not (except by accident) a great hero standing up for the truth in the face of persecution; and the Catholic authorities were not trying to prevent the spread of new scientific ideas in general, and did not care very much one way or the other about heliocentrism (which they saw as a matter of very little religious significance). Note that Copernicus himself was a well respected cathedral canon and suffered no persecution whatsoever for his astronomical ideas. Neither, to any significant extent, did Kepler, Galileo’s contemporary, who was a much more outspoken advocate of heliocentrism than Galileo ever was. (True, Kepler was a Protestant, and, in fact, Luther himself is said to have remarked, offhand, that heliocentrism is absurd because it contradicts the Bible. The point, however, is that this never translated into any religious problems for Kepler, because no-one thought astronomy was of any religious significance.)
The story of Galileo’s trial and condemnation is a comedy of errors, shady politics (the full details of which are probably, now, beyond the reach of history), perhaps petty spite (on Urban’s part) and, on Galileo’s part, careerism mixed with arrogance.
No.
Galileo became famous, initially, for his telescopic observations, and later for his contributions to physics. He was not “a ‘lightening rod’ for the heretical views of his contemporaries” because it never really occurred to anybody that heliocentrism might be heretical (at least in any way that mattered) until Galileo started getting people (mostly professors with careers in teaching Aristotelian physics) pissed off at him. At that point, the claim that heliocentrism contradicts an obscure quite theologically insignificant passage in the Bible was dragged up as a way to try and discredit him. (In fact, it requires a pretty tendentious reading of the Bible passage in question to make it even seem like a superficial contradiction, and, in any case, the Catholic Church of the time was in no way committed to reading everything in the Bible literally. They were not modem American fundamentalists.) Initially, the powers-that-were in the Church found this accusation quite ludicrous, made the accusers apologize humbly to Galileo, and punished them. It took about another 16 years of misunderstandings, political intrigues, and arrogant (or, at last, politically inept) moves on Galileo’s part to turn this situation into one in which he would be put on trial (and not directly for heresy, by the way).
No.
Someone actually calculated how long it would take ordinary glass to measurably flow at room temperature (such that you could detect thicker glass at the bottom of a window pane, for example) and came up with a length of time “well beyond the age of the universe.” An analysis in the American Journal of Physics (May 1998 – Volume 66, Issue 5, pp. 392-395) actually came up with a figure of 10[sup]32[/sup] (100,000,000,000,000,000,000,000,000,000,000) years to see any measurable changes at room temperature.
I don’t think you’re going to get your “puddle of glass” on the Moon in any time period as short as a million years. The Sun will likely expand into a red giant first, or more likely, your sculpture will be destroyed by meteorites (micro- or otherwise).
Cite.
well i suppose i meant ‘lightning rod’, not sure what a ‘lightening rod’ is.
ok, well what you’re saying does sound consistent with the asshole theory. so what about the renunciation story? it does sound rather sensible to just say ‘ok, you’re right’ out loud, and at least be thinking ‘but you’re not’. is this mythology or reasonably based in fact?
Just thought of another one. In history class I was pretty much told that WWI was so deadly due to machine guns where the gunners would simply rake across the attackers. Pretty much like is shown in this at about 8 minutes in
Turns out this doesn’t work. The next section shows the actual tactics used for machine guns in WWI. (Which actually made the machine gun so effective.)
Galileo was forced to publicly declare at the end of his trial that he now accepted that it was completely false to say that the Earth moved. (Actually, Galileo’s mouthpiece in the book, Salviati, says more or less the same thing at the end, or, at least, that there is no way of knowing, which is how Urban had demanded that the book should conclude. However, it is not very convincing. Salviati folds far too suddenly and easily.)
There is no credible evidence for the story that he muttered “it moves all the same” (or whatever that is in Italian) and, frankly, it would have been insane of him to do so. He wasn’t that arrogant!
On the other hand, I also find it hard to believe that he actually changed his beliefs. I do not know if there is any written evidence on the point, bu the did write Discourses on Two New Sciences after his trial, and although it does not deal with astronomical matters a lot of his revolutionary work in mechanics was published there for the first time (although based on research he had done much earlier).
I think the fact that he was allowed to write this book whilst technically a convict and prisoner of the inquisition (actually in very comfortable “house arrest”) is quite telling. They clearly were not really all that mad at him.
I also think “asshole” is a bit strong, though it is true that he could be very, and publicly, sarcastic towards people (sometimes quite powerful people) who he thought (not always rightly) to be fools. He didn’t think everyone who disagreed with him was a fool, though. He appears to have had great respect for (and to have been respected by) Cardinal Bellarmine, for instance. (Bellarmine has often, quite wrongly, been depicted as the villain of the piece.) Some people hated him, but equally clearly, there were others who thought he was a lovely guy. I would say he was arrogant (but with cause), and on the make. He (probably, there is no direct evidence I know of) deliberately stirred up controversy because he thought it would make him more famous and give him a shot of becoming court philosopher to the new, progressive pope, and the scheme backfired badly, for reasons largely unknown.
It has even been suggested (by Pietro Redondi) that he was a fall guy for the pope himself. There is some evidence that there were concerns that an attempt was in the offing amongst the more conservative cardinals to declare Urban a heretic (on charges far more serious than supporting heliocentrism) and depose (and, no doubt, burn) him. Things were politically very hot. The 30 years war was going very badly, and setting the relatively progressive French Catholics, who had got Urban elected, against the more conservative Spanish ones. Apparently the pope’s brother, who was a cardinal, almost got into a fist fight with one of the Spanish cardinals on one occasion. Urban’s long, friendly association with the controversial Galileo might have come to have seemed a real liability. If that is true, he found a very clever way to publicly distance himself from Galileo, whilst at the same time making sure that the charges against his friend were not too serious, and that his punishment would not be too severe. There is even some suggestion that, Galileo may have been clued in to what was really going on in the middle of the trial, and agreed to take the fall (he had a long private talk with one of the judges, and seems to have stopped bothering to put up much of a defense after that). Presumably Galileo knew that if Urban was deposed and burned, he would almost certainly be burned too.
The evidence to support that story, however, is very meager. If there was ever a paper trail, it has been destroyed, or else buried in the parts of the Vatican archives that nobody ever gets to see. Still, it appeals to the conspiracy theorist in me, and does seem to tie up a lot of the otherwise loose ends.
Myth!
Most teachers love it when our students are able to shed light on a subject or bring in something new. Some of us even challenge our students to catch us in a mistake.
No one likes cockiness and unfortunately for you, the class and the teacher, he let his reaction to that take priority over an open mind and a learning experience.
1972? You are a child!
It has been found on a portrait dated about 1640, which indicates that the quote was attributed to him not long after the trial, and well-known.
http://www.er.uqam.ca/nobel/r14310/Ptolemy/Galileo/Sustermans.html
Most good teachers, you mean. I suspect we’ve all had teachers who did not appreciate being corrected, no matter how politely it was done. I know I have (and how…).
What? 1640? It took them a full 8 years to come up with that story! :eek:
I don’t doubt that he thought it. I don’t doubt that many people at the time, very likely including Urban and the Holy Office officials who prosecuted and condemned him, didn’t doubt that he thought it. But are you seriously suggesting that he said it, right there in the courtroom? Gimme a break!
It’s still a good rule. Puking in the pool isn’t fun. I still believe there’s an increased risk of cramps after eating.
Do you want to play a vigorous game of basketball after a big meal? Most people wait awhile. It’s a comfort issue. Same thing with any exercise after a meal. It’s not going to kill you, but why make yourself sick for nothing?
I taught my kids to wait before jumping in the pool. Just because some some medical research proved “technically” it’s ok. Doesn’t mean a rule followed for generations goes out the window.
I think I’m right in saying artillery caused most of the casualties.
Of course. I was just pointing out that the belief that a lock failure would be catastrophic is true, although not for the reason that someone’s teacher seemed to think.
I believe there was some talk when the French were trying to build their canal that one of the ends might be a few feet higher than the other, or have higher tides which could cause problems. I don’t remember the details though.
Yes, like the one I tried to point out how much of that Galileo/church stuff was myth. (You know, the myth about the church being totally pro literalism or Galileo being just some innocent scientist persecuted by the the church.) He actually pointed out it took the church hundreds of years to apologize for it. (My understanding was they used the Tychonic system which explained the evidence and only had to throw it away in the late 1700 to early 1800’s. At which point G had already been dead for around 200 years so no real reason to go around digging up issues. If I had been quicker I probably should have asked if they were so against science how’d they let a guy like Mendel do his work?)
Nope, he didn’t like being corrected. (Actually come to think of it he also thought sapper tunnels worked because the burning wood generated enough heat to crack the rocks. Really I know enough now to know that’s a laughable idea.)
I believe that’s correct actually. The thing I was trying to get across is the answer to the question “Why didn’t charges work like they used to and why did they sit in the trenches all the time?” The standard answer was they’d just rake across with machine gun fire to prevent assaults. The real answer is apparently what’s shown in the video. (Using the guns on the flanks and waiting until the enemy got close.)
It’s the same principle as raking fire from the days of wooden ships, and a lot like the principle of absorption in optics – the odds of your bullet hitting something and performing a useful service (rather than flying off uselessly into space) is vastly improved by making sure that it passes through a great length of dense absorbers. so instead of firing at normal incidence on a thin line of the charging enemy, you fire at as steep a diagonal as you can down the length of the line. Your odds of a given ullet striking a soldier increase dramatically.
Of course, you have to wait until they’re closer, and you can’t cover as large an area, but you rate of effective fire and your efficiency get much greater.
I’m glad you posted that – I’d never really thought about it, and no one had ever told me, but I’d assume that machine guns were mainly used in the straight-on and sweep mode, if I was asked.