This History of Science video will be mostly about the Copernican Revolution in astronomy, or rather about several common misunderstandings about the Copernican Revolution. So the Copernican Revolution was introduced by Copernicus around about 1514 and was opposed to the system due to Potolomy which had been around since about for about 1500 years. So the Copernican system had the sun at the centre of the solar system with the earth moving around it and the Potolomy system had the earth at the centre of the solar system with the sun and all planets moving around it. And to reason, the Copernicus was simpler and gave a better fit to observation and was more correct because it predicted the earth was moving whereas Potolomy's system incorrectly predicted the earth wasn't moving. Well almost everything I've said about Copernicus's system is wrong as I will now explain. First of all it wasn't really due to Copernicus. It was first introduced by Aristarchus or possibly by somebody even before that probably about 16 or 17 centuries before Copernicus. So Aristarchus was a Greek astronomer and the Greeks had managed to measure the size of the earth and the distance to the moon and the distance to the sun and they got the size of the earth pretty much correct and they got the distance to the moon and the size of the moon pretty much correct and they got the distance to the sun rather wrong because measuring the distance to the sun was a very very difficult measurement. They had to measure the angle between the earth, moon axis and the earth, sun axis at a very precise time when the moon was shadow of the moon covered exactly half the moon and this involves measuring an angle extremely close to 90 degrees and they couldn't really quite get it right. It's a very difficult measurement. Anyway, although they didn't get the distance to the sun right they got it right enough that they figured out the sun was very much bigger than the earth and Aristarchus had this idea that if the sun was much bigger than the earth then maybe it was the earth that was orbiting the sun rather than the sun that was orbiting the earth. Anyway this was sort of more or less forgotten for many centuries until Copernicus came along Copernicus incidentally correctly credited Aristarchus with this idea Copernicus didn't claim his ideas being original he was reviving an old idea due to Greek astronomers. So the first problem is did Copernicus's theory give a better fit to observation than Potolomy's theory and the answer is very clear it gave a worse fit to observation. The problem is stellar parallax suppose you've got a star now if the earth is moving around the sun the angle from the earth to the star should vary with a sort of yearly period because the earth is sort of moving backwards and forwards by a few hundred million kilometers and this angle is changing the angle of the stars called stellar parallax and there wasn't any stellar parallax people looked for it and it just wasn't there. It wasn't discovered wasn't measured until more than three centuries after Copernicus came up with this theory Bessel he's the guy who invented Bessel functions in 1838 finally managed to measure stellar parallax. The problem is it's very small and need very sensitive instruments to measure it. Galileo did correctly suggest that the reason why stellar parallax wasn't observed is that the stars were so far away that it was too small to measure but you could perfectly well say that Galileo was just inventing this ad hoc excuse for why Copernicus's theory failed. Incidentally as everybody knows Galileo got into serious trouble with the Catholic Church for claiming the earth went round the sun. Well that's probably not the real reason he got into trouble. I mean Copernicus had claimed the earth went round the sun and no one was really that bothered by it. The real reason Galileo got into trouble appears to be that he sort of publicly mocked and insulted some rather powerful people who disagreed with him and as these powerful people were also rather powerful people in the Catholic Church they were able to use the Catholic Church in order to get at their enemies so he seems to have, one gets the impression he was in trouble more because of scientific rivalry rather than because of any theological problems. But anyway, the next question is was Copernicus's theory simpler than Potolomy's theory and the answer is no it wasn't really. So Potolomy's theory needed a lot of epicycles in order to make sense of observations. So what is an epicycle? Well if you take the earth, well an epicycle you have you think of a circle going round the earth and then on this circle there's another thing going round in a circle around that point and then on this there's another thing going round in a circle about that so it's very complicated. You have this thing going round in a circle and this thing going round in a circle maybe a planet is going round on this thing so the planet is going round on some complicated path and Potolomy needed quite a lot of epicycles in order to fit the movements of planets so this whole system looked like a rather complicated mess and you can say isn't Copernicus's system much simpler because all he had was the sun and a lot of planets moving in circles around the sun except that didn't work. If you take the sun as being in the centre of the solar system and planets moving around on circles it simply didn't fit observations. What Copernicus had to do is he had to reintroduce epicycles again in order to make his model fit with observations so it wasn't really any simpler than Potolomy's theory both of them used large numbers of epicycles. Copernicus's system only became better than Potolomy's system when Kepler came along and pointed out that the planets seemed to be moving around not in circles around the sun but on ellipses around the sun with the sun at one of the two focuses of the ellipse and once you've done that Copernicus's system finally becomes better than Potolomy's system. It's still not completely correct of course because Newton pointed out that the planets are all perturbing each other and the sun isn't quite stationary because it's perturbed by Jupiter and Saturn and so on. So once you've added Kepler and Newton then Copernicus's theory finally becomes a reasonable fit to observations. Incidentally there's a problem that John Conway liked to ask people which is what is the orbit of the moon around the sun? So the problem is you should try and sketch roughly what the moon's orbit around the sun looks like. So you remember the moon is moving in an ellipse around the earth and meanwhile the earth is also moving in an ellipse around the sun. It looks like the orbit is going to be kind of complicated and most people when asked this question sort of get the answer quite wrong. You think it's going to be something like this. So here's the sun and maybe the moon well the earth is going to be moving around on an ellipse and the moon is going to be moving around the earth so maybe it should be looking something like this or maybe the wiggles aren't quite that big and it should be moving in a sort of bumpy curve like this and both of these are completely wrong. The moon's orbit looks nothing like that or like that. This is what the moon's orbit actually looks like. The moon's orbit looks like this. Here we have a circular template and this is the moon's orbit with the sun almost but not quite in the center. So what happened to the moon orbiting the earth? Shouldn't there be some bumps in this because the moon is going around the earth? Well, no. The distance from the moon to the earth is about a thousandth of the distance from the earth to the sun so if the earth is moving around like that the moon it will be moving in almost exactly the same path the difference will be a thousandth of this distance here which as you can see is much less than the thickness of this line so the orbit of the moon is indistinguishable from this circle. So the next question is why is this a circle not an ellipse? Didn't Kepler teach us that the earth orbits in an ellipse around the sun? Well, sort of. However, this ellipse has very small eccentricity and ellipses of small eccentricity are indistinguishable from circles to the native eye. The only difference you might be able to see is that the sun is not quite at the center but the difference is very tiny. You could probably just about make it out. It would be a fraction of a millimeter off at this scale. So if you're a really good eyesight you might just about be able to detect the sun isn't quite at the center. So the moon's orbit around the sun is for all practical purposes a circle, not some funny wiggly line. Kepler discovered planets moving in ellipses rather than circles because he was looking at the orbit of Mars and Mars's orbit has a much higher eccentricity than the earth's orbits and you really can tell it's not moving in a circle. Incidentally, the reason why Ptolemy's theory about epicycles work pretty well is because the earth's orbit being an ellipse of small eccentricity is very close to being circular and you can make it almost exact by adding another small epicycle to account for the fact the sun isn't quite at the center of the ellipse. So the earth's orbit around the sun is actually fitted very, very well by an epicycle as used by Ptolemy. The final problem with Copernicus's theory is this claim that the earth is moving. Now, saying that the earth is moving isn't really true. It isn't really false either. It's not a matter of something being absolutely true. It's a matter of which coordinate system you take. So let me give an example. Suppose you're trying to describe a spiral. Now, if you're trying to describe a spiral, it's usually easiest to use a polar coordinate system where you measure points on the spiral by radius and angle. If you try describing a spiral in a rectangular coordinate system, the equations describing it are going to be a bit of a mess. However, anybody who said a polar coordinate system is true and a rectangular coordinate system is false would be kind of stupid. Coordinate systems aren't true or false. They can be convenient or inconvenient. And you could say a polar coordinate system is convenient and a rectangular coordinate system is inconvenient, but you can't say this one is true and this one is false. And the same is true for the difference between Copernicus and botolomies theory. They're just different coordinate systems. So two coordinate systems. The first one is you take the Earth fixed. And if the Earth is fixed, the Earth isn't moving and the Sun is moving around the Earth. If you take the Sun to be fixed, then the Earth is moving in a circle and the Sun is moving around it. Sorry, the Earth is moving in a circle around the Sun. So if you want to describe positions of planets, then the coordinate system with the Earth fixed is really rather a mess. It's kind of like trying to describe spirals in rectangular coordinate systems. It's just unnecessarily complicated. So if you're an astronomer, you should use the coordinate system with the Sun being fixed. If you're trying to send a probe to Mars, so suppose you're NASA and sending a probe to Mars, then again, it's much easier if you choose a coordinate with the Sun fixed and the Earth and Mars moving. On the other hand, if you're a normal person, say you're a sailor in a sailing boat, then, and you're trying to work at which direction to go in by looking at the Sun, it's much easier to imagine the Earth being fixed and the Sun moving around it. This doesn't mean that your coordinate system with the Earth being fixed is true. It just means it's easier to work with, just as for an astronomer, this coordinate system is easier to work with. Well, you could say, well, you know, you should take a coordinate system with the Sun is the centre of mass of the solar system, so it's better to use a coordinate system at the centre of mass of the solar system. Well, why? Well, first of all, the centre of mass of the solar system isn't quite at the centre of the Sun. It's actually near the surface of the Sun because of Jupiter's influence. Secondly, what's the great thing about the Sun? Why not take the centre of mass of the entire galaxy, in which case you find a yet another coordinate system, or you could take our local galactic cluster and you can keep going up until you reach, say, the cosmic microwave background. Now, in the cosmic microwave background, you can actually detect the Earth and the Sun moving with respect to it. And the speed of the Earth and Sun with respect to the cosmic microwave background is about 10 times the speed of the Earth with respect to the Sun. So here, the Earth is going to about 30 kilometres per second. And here, there's nothing special about saying the Earth orbits the Sun. This coordinate system is no better than the coordinate system saying the Earth is fixed, or the coordinate system saying the cosmic microwave background is fixed and the Earth is moving along the straight line. And which of these coordinate systems do you use? Depends on who you are. So a cosmologist studying the expansion of the universe would use this coordinate system. An astronomer would use this coordinate system and a sailor would use this coordinate system and none of these systems are either right or wrong. And arguing about whether the Earth moves or not is as silly as arguing about whether a polar coordinate system is true or not, or for that matter arguing about whether the metric system is true or not.


My name's Fred. As he mentioned I run WP shout and press up Okay, we're talking about technical communication. What is that? It's explaining hard things to humans and we're gonna break down each piece of that. Hold on. I'm actually taller than this All right. Okay. Um That feel when you're too tall for that. Okay. All right. So hard things to humans explaining hard things to humans What are hard things? There are things that take a lot of specific technical knowledge knowledge that is basically unrelated to human intuition So, you know if you were traveling to a new country and somebody said, oh, you know Just be your normal self, but maybe be a little bit quieter. That's considered polite That's sort of that's got a lot of human intuition in it. That's not technical But if somebody said yeah, just write a WP custom WP query unless you know the exact nature of how to do that You don't under you you don't know where to start. That's technical knowledge. It basically has no relationship to human intuition Explaining what does this mean? It means conveying knowledge effectively enough that a specific goal is achieved So people need information to be able to do things now for for a coworker They might need to know everything you know about a particular topic, but for a client the goal might be Just that they have enough general information to have the intuition. They need to make a decision So explaining means that you you solved somebody's problem, whatever the nature of that problem Who are humans? Well, they're imperfectly rational They learn differently. They don't like to feel like the only person in the room. It doesn't know what's going on they don't like to be talked down to and Not only is the person you need to explain stuff to a human, but you yourself are a human and that's that's the tricky part So and then why does technical communication matter? Well again, you know we mentioned goals, right? My cousin says he can totally build this site with Yahoo's free page builder in language I can understand tell me why I should pay you any money to do it, right? I mean goals if you want to get this guy on as a client, which you maybe don't Yeah, you know WordPress sounds great for this project, but my boss is really worried Don't people say isn't WordPress easy to hack, right?  I can't understand a word of it Okay, so what is technical knowledge? Well, we're gonna use an analogy here. Technical knowledge is like being on a hill I actually found a picture of a hill. Here's the hill and I'm gonna sort of diagram it out for you So here's you right at the top of the hill from the top of the hill. You can see a view, right? There's the hill that you climbed to get to the top and then the sort of default before you climb the hill Is the valley and that's where most people live and they are of course the valley people So the hill and you Getting up the hill took effort, right? It's not a trivial process You had to walk every step of it up from the valley where we all start up to the top But now that you're up there There's an amazing view you can see and do all kinds of cool stuff You can see the weather forming a thousand miles away You have superpowers basically and those that stuff you can do the the stuff that the view enables you to do You're passionate about that's why you climbed the hill in the first place Now the valley well It's a wonderful place to be for any piece of technical knowledge like 99% of people are in the valley, right? So it's it's the default on the only thing is the valley sometimes needs hilltop information And that could mean you either need to provide instructions for climbing the hill or a lot more commonly You need to provide a report from the top of the hill describing the view in language that valley people can understand Why is this difficult well gaps in knowledge and one thing I want to point out is that we sometimes treat gaps and knowledge like there's just specific pieces of information that people need but The way that gaps and knowledge chunk together is that eventually there are entire Context just whole sort of domains of information that are separating you and the people you need to communicate with So it's not like oh if I could just communicate these ten facts It's more like if I could communicate the underlying sort of knowledge base Then I could even could communicate the ten facts and here's an example, right? Hey, look the permafrost is thinning on the peaks of the western mountain range that on the valley They're thinking okay permafrost peaks mountain range, right? They have no idea what you're talking about What is this? Lead to and in sort of the worst case it leads to attitude problems And what I'm talking about is attitude problems that you have as a technical person the first one is arrogance I am actually only interested in speaking to other people on this particular hilltop, right? What does this look like arrogance? Has anybody ever found a talk to an arrogant developer?  I mean do you know do you know it like as an accusation, right? They make you feel like an imposter right and they don't care whether you understand them or not because they know They're right and whether you can get with that or not who cares so a rock star, right? That's that's kind of arrogance personified and given a guitar, okay? Now where does arrogance come from well sometimes you know bad manners, but more often it's that people You know love clarity they love the view right and you who have no ability to understand that that view are just sort of bringing confusion into their whole thing Why would I try to explain this knowledge that it cost me a lot to acquire it to people who have no context for it Right, then the second attitude problem is called breezy-ness. What is breezy-ness? It's so easy to get up here. Actually, I'm just gonna assume that you're up here with me anyway now Let's talk about the view in extreme detail right breezy-ness You're trying to pretend that gaps of knowledge don't exist and and so you exceed other people's ability to learn You use way too much tacit knowledge Which is background knowledge that people need to understand what you're talking about that you assume they have that in fact They may not you know so you sail over other people's heads you skip the basics and you dive right into the to the Stuff that you want to talk about that you think is cool and you're constantly going this is so easy This is so simple. This is so logical right, but it's I mean it is to you right The the view is so cool. It's sitting right there and it's this awesome thing to you But remember only you can see it and it costs you a lot It took a lot of climbing to get there and you're kind of ignoring this fact and that's what I'm calling breezy-ness So the basic problem in both cases I believe is that you're blinded by the view. It's so cool It's beautiful right and and that and that focus on what you know As opposed to what other people need to learn is becoming an impediment to communication Your knowledge is so important to you that you can't properly communicate that knowledge to people who need elements of it Okay, so Those are what to avoid now. What can we do instead? Well, I think there's two things are really helpful to keep in mind if you want to communicate technical knowledge effectively The first thing is that your communication should be audience aware the second is that it should be strategic And we're gonna talk about both of these audience aware Communication means start where your audience is reason carefully and without bias about what is likely to be the extent of the technical knowledge of the people you're talking to and Then communicate in a way that reflects that understanding and actually respects where people are are at and doesn't wish they were You know somewhere else And here are a few strategies for this one is to use analogies, right? Analogies like the hilltop analogy that we're using it may phrase is your own understanding in terms of other people's understanding It's a sort of a form of translation and it can be so valuable in getting the key points of a piece of technical knowledge across Right. So how does WordPress work? Here are two examples one without an analogy and one with well WordPress stores post another date And it's my sequel database and users appear I can't I don't have time to finish all this But it means nothing to like a hundred percent of human beings, right? And then number two WordPress is like a factory that builds webpages The database is like the warehouse where the raw materials sit and then they come through a factory And that's what the PHP processing is and then you've got a theme and that's that's all the assembly lines that the raw materials go Down, you know, maybe there's a page assembly line and a single assembly line and an index assembly line And that's your theme and then sometimes we need stuff that the factory can't do by default and then we call on outside contractors And those are called plugins, you know, I mean in 20 seconds somebody has a decent idea of what WordPress is with none of the specifics Which is what you want Okay, another thing you can do to be audience aware is To actually list out the knowledge that what you're saying depends on you remember tasks at knowledge is basically how you communicate Breezy breezy with breezyness here being like a really bad thing, right? So how far up the hill are we starting and if we're not starting at the bottom at the valley where everybody is What can I the listener do to get up to the starting point? You know, you don't want to just start you don't want to just be like oh great now that you're a thousand feet Here's how you get to 1800 where the hilltop is right you want to say this is how you get from zero to a thousand So this again, I don't have time to read it But this is the like what hits you when you go to like the introduction for noobs page of grunt, right? And for me, it's like I I just bounce off this it's like runs not for me, right? How how about like an intro to using the command line for people who you know Who aren't where they need to beat it to use ground but would like to be right? Okay, so that's audience aware communication now strategic communication That means once again tie your communication back to the goal of it You know people need to know your knowledge not for no reason but for some reason and you want to actually reason about What is what what do people need to know and you want to tailor your communication to that? Right, so let's say a client is asking you what's WordPress the first thing is just the Wikipedia description of WordPress It's a free and open source blah blah blah, right? But the second thing is WordPress makes it really easy for you to use your website and guess what it also makes it quick and easy for us to build That website and if you'd like to know the specifics we'd be happy to explain it like I as a client It's like I want that I would love to pay for that and if I have questions I have a lot of confidence that you know that you can give me you know more But maybe this is all I need to know to be like great. You're hired, right? So this is strategic communication. It's sensitive to the reason that you're communicating in the first place And actually this can do a lot for your writing There's a couple examples that I'm going to go through very very quickly But like here's one basically a conditional tag is just a function that how about just a conditional tag is a function Right because our purpose is to explain something not to emphasize how easy the thing we're explaining is and so those those two words They're not strategic. So they're gone and I'll skip this one sort of a similar principle, but this is actually in the WordPress Like this is in WordPress success WordPress has been installed. Were you expecting more steps? Sorry to disappoint and How about success WordPress has been installed? Thank you and enjoy because again our purpose is what's our purpose? Is it to make people feel kind of snarky about how easy WordPress is? It's like that makes no sense like what if the person had a hard time installing WordPress like I did the first ten times, right? I mean, it's not very strategic. So that's that's my little plug for Overhauling the way that WordPress is sometimes written.  Don't do that and don't be breezy meaning don't pretend gaps in knowledge don't exist, right? Those are those are two no-nos and actually communicating to other human beings and Do be audience aware and strategic audience aware means what is the knowledge level of the people I'm talking to and how can I communicate in a way that respects that and Strategic means why are we having this conversation in the first place? What is this leading to and how can I tailor my communication to that? Okay, and then this is a final note just on empathy You can you can do all this pretty well and still not be very nice and when you're not nice you kind of put people on edge and People who are on edge tense people tend to have a hard time learning. So here here's how to have empathy in two very simple hacks Which is a I'm turning into a BuzzFeed article after this so look out for that but Okay, so when you're speaking smile as you talk and See see if anything changes if you just sort of physically smile as you talk And if you're writing put a little smiley face after every paragraph and delete or rework anything that sounds sarcastic and Boom empathy acquired Okay guys, so that's communicating technical knowledge And that's how to be on the hill and help the people in the valley either get up the hill or learn You know the elements of the view that they need to live their happy lives in the valley. Thank you so much


Let's see two ways to do it. Being in your Zoom account, go to the top menu and click on Meetings here. A new page will open. On the left side you can see a column with the different meetings that you have scheduled. In our example, you see two of them. Now select the meeting that you want to share by clicking on it. When doing so, information related to the meeting will appear on the right side. When you click on Show Meeting Invitation, you will see who created the meeting, the topic, time, the link, ID and password. Now click on the Copy Invitation button here. All information about the meeting will be copied. Now you have to paste your link. I will do it in an email and send it. When the person receives it and opens the application, where he will have to enter the ID and password provided in the message. And that's it. Now let's see a second way to do it, but now while we are already in a Zoom meeting. Go to the bottom menu and click on the Participants icon here. A column with the participants' names is opened. Go to the bottom and you can see the Invite button here. Click on it. A new window is opened with the following information. In the top you can see the ID and on the bottom the meeting password. So as you can see these two buttons, Contacts and Email. In the Contacts section, you will see the contacts you have in your Zoom account. When you click on the Email button you will see these options, Default Email, Gmail and Yahoo Mail. Just choose the one you prefer and follow the instructions. Another way to get this same window is by clicking this arrow next to the participants' icon here and here. Now of the two options, select Copy Invite link here. We recommend this option because it's easier. When the person receives the link invitation, he only has to click on it and he will be taken to the Zoom website or the application to access the meeting without needing an ID or password. Easy right? Now inviting to your meetings in Zoom will be easier. Time to learn is working to help you understand the changes in technology as they happen. Stay in the know. Subscribe today!