LudwigVanQuixote
General • 1 week, 2 days ago • Clicks: 100 • Views: 331

It is conversations like this that make me love LGF. This is also a topic that I think many here can join into for a larger discussion.

Things in quotes are from Curious Lurker, one of my favorite other lizards!

I think that for a lot of people, like myself, scientific data is intimidating. My last contact with anything even remotely scientific was probably in biology class in high school 30 years ago, so unless something is explained to me in very clear & simple terms, I have a hard time wrapping my head around it.

Many people are in that position. No one can know everything. No one person can even know everything that human beings have figured out. Because of that, something that everyone needs to work on developing are skills that check to see if some scientific claim “rings true.” It isn’t that you need to be able to calculate the orbit of a satellite for example. It is sufficient to understand that a satellite has to be moving very fast in order to maintain its orbit, so if someone told you something that would mean that satellites are moving slowly, you would instantly know they were full of crap. For example, in the case of AGW, I recently posted a video that had two people do a table top experiment that showed that having more CO2 in your air means it must get warmer when you hit it with IR light – and in fact, both jars, in both experiments got substantially warmer. Again, you do not need to be able to calculate exactly by how much, to know that doubling or quadrupling the amount we have in the atmosphere must heat up the Earth.

I know this will probably horrify those of you who understand & have an ongoing interest in science (or who are actual scientists), but for the rest of us, accepting things like AGW is sort of like religion—i.e. we believe it as a matter of faith in the messenger (or disbelieve it due to lack of faith, as the case may be).

This is the greatest challenge that scientists face in trying to deal with anything scientific that has become politicized. People want to believe things they like and don’t want to believe things they do not like. Science is most assuredly not religion however. All of the evidence is there for anyone who wants to look. Everything always comes back to the very real nuts and bolts of what the actual physical world is doing in ways that can be verified.

Are people willing to look, and on a deeper level, have they exercised the mental muscles lately to know how to look? Science is not about hearing lists of facts. It is an active engaging process where the implications of facts are put together to make consistent pictures. It is not a history book, but rather more of a murder mystery. Clues come in and the culprit is identified. It is something active that you engage in and reason through. However, science is taught as yet another story to memorize – something passive. As such, it becomes yet another thing to be cynical about when someone lies to you, like ghost stories, or tooth faeries.

The problem of course, is that charlatans claim the mantle of science for their own ends. The trust that people might place in experts is eroded by the latest “scientifically proven” fad diet.

This is even further complicated by shoddy reporting where controversies are generated to create drama that does not really exist in the scientific community. As far as the legitimate scientific community is concerned, everyone gets what the notion of a GHG is for example and that CO2 is one.

The thing for you to do is to look for the basics and see if what is being said rings true with the basics. If someone says something doesn’t make sense, ask.

For example, AGW deniers like to make up all sorts of stuff about CO2. Just ask them, since you know and have seen that it absorbs IR and gets hotter when it does, how it is possible that all the teratons of extra CO2 we put in the atmosphere are doing nothing.

I’ve tried to understand AGW, but it’s so politicized and there is so much data that it becomes confusing and I give up in frustration. It doesn’t help that a lot of the data is in the form of graphs, charts and tabular data, or photos of things like smokestacks, OR it is described using terms/concepts I don’t fully understand.

So here is a fabulous resource written at an “everyday” level.

[Link: earthguide.ucsd.edu...]

This is a full course written at the freshman level from UCSD.

I think that in many ways AGW parallels the whole Islam is/isn’t compatible with Western society thing. In both cases members of a community are trying to get a message out, but either they aren’t being heard, aren’t delivering the message in a way people can understand, or the issue has been so politicized and the opposition so strident that some folks won’t believe anything they say regardless.

Well, here we get into the entire “whom do you trust” aspect of this. Do you trust actual practicing Muslims who are obviously educated and decent floks about what their own religion says and does not say, or do you trust Fox News?

By the same standard, do you trust the legitimate scientific community, or do you trust Fox news?

Of course, there is an even deeper difference. Debates about beliefs can go on forever without resolution. It is easy to color the language of belief or to take pieces of a doctrine out of context. This is done both by the practitioners of a religion and those on the outside. It is very easy for any charlatan to make what he will out of any faith – and if his message has the right mix of hatred and superiority, it will attract the basest and most vile sorts.

For certain, the Islam of someone from Hamas or the Taliban is not the Islam of an educated, kind hearted person.

The Christianity of Fred Phelps, or Sarah Palin, is not the Christianity of Mother Theresa. Could you see either of those two dedicated to a giving, humble and charitable life of helping others in need?

The Judaism of the rasha who assassinated Itzak Rabin is not the Judaism of the Rambam.

With science at least, all of those conflicting voices who represent the best and the worst of us in the field of religion, are always secondary to the hard data. If you believe that God made the universe according to His will, then you must believe that all natural phenomena are according to His will. As a result, the final arbiter in science, is God Himself. Paradoxically, with religion, the final arbiter of what people think God said, is always men.

LudwigVanQuixote
Science • 1 week, 6 days ago • Clicks: 77 • Views: 519

This is a brilliantly simple demonstration done by both a professional scientist and a kid for science fair. Seeing is believing.

All those deniers could try this themselves actually.

Peter Sinclair then goes on to hammer the point about the effect on the Earth as a whole. The very basic and well understood physics here is part of why the open denialsphere appears so incomprehensible to the legitimate scientific community.

Not to be too blunt, but you have to either be seriously stupid or, in the case of those with credentials, utterly sold out or just plain crazy, to pretend that somehow the teratons of CO2 we have added to the atmosphere have no effect.

The debates of real scientists in this field all come down to how much change, how fast and how bad. No one, but an idiot could imagine, that the CO2 will not cause warming, or that the changes that come from it will be good for everyone.

Further, in terms of how bad, how fast and how much, all the incoming data, shows that the changes are happening rapidly, and in certain coastal areas and areas that depend on melt waters for their drinking water, already catastrophic. There is no reason at all to assume that will not get much worse and spread over a much wider area in the coming decades. Crops require the right temperatures and amounts of rain to grow. Already, this year alone, the effects of AGW coupled with the Pacific oscillation caused disastrous flooding in Pakistan and failure of the Russian wheat harvest. While the severity of future predictions, assuming no change in our emissions, varies, there are absolutely no predictions that are not disastrous. There are no happy outcomes. There are only some which are less terrible than others. How bad is literally a question of how bad.

Update:

Apparently, the frauds at WUWT have made a counterclaim about it.

[Link: wattsupwiththat.com...]

Just to debunk it…

The proper demonstration uses a powerful 200W lamp that gives off a lot of IR, right up close to the tanks.

This is done so all of the light emitted has a chance to go into the tanks and most importantly, to compensate for the tanks equilibrating to room temperature.

A tank of any warm fluid will come to room temperature. Gasses with low specific heats, and in thin walled tanks, with lots of surface area to exchange heat with the room’s air, will cool to room temp very quickly.

This is basic thermo. Something which none of them understands.

So, WUWT, “did the experiment” by placing the tanks about a half meter back from a 60W house bulb.

Of those 60 W, most of course, went up towards the celing or down towards the table, and only a fraction of that energy was available to interact with the tanks.

Just to make certain they could skew the results some more, the WUWT people used a cold room. Heat transfers faster, the greater the difference in temperature. This is also basic physics.

So yes, WUWT, when you skew something so it won’t work, by making certain the system cools faster than you are heating it, it doesn’t work.

This is a fabulous example of people simply lying about science. It took talent to —- up the measurement that badly.

LudwigVanQuixote
Science • 1 week, 6 days ago • Clicks: 17 • Views: 223

Last time, we wrapped up by stating the first law.

It is no more or no less, than saying that energy is conserved. In other words, you can’t win. You can never get more energy out of a process than was put in.

Specifically, dU = dQ – dW.

Mathematically, this says that the change in total energy of a system is the change in heat of the system minus the change in work done by that system on something else.

Let’s try to make that concrete. Last time, I talked a lot about how if you heat a gas, what that means is that the molecules or atoms of the gas have more kinetic energy, they literally move faster, and smack the walls of the tank harder. Hence, pressure goes up.

So consider the following set up. I have a cylinder filled with some gas. However, I am going to add some heat to it with a small burner, or perhaps by putting it in a warm bath, it doesn’t matter, and I have a piston on the top.

Moving the piston takes energy. How much energy isn’t hard to calculate. You just need to remember that pressure is force over area and integrate over the distance traversed. Remember that work is the integral of force through distance. The differentials work out to integrating PdV. For those who don’t want to worry about the actual calculation, don’t worry about it. The important point is that it took some energy that came from somewhere to move the piston.

So, we are heating up the gas, which in turn, is moving its atoms or molecules faster, and smacking the piston harder. The piston goes up.

What the first law is telling us, is that we dumped some energy into the system, and that all of the energy is accounted for. We didn’t get anything for free. Any change in the overall energy of the system was exactly accounted for by heating the gas (and cylinder), and whatever work was done in moving the piston. As the gas pushed it transfered energy (which we covered in the first lecture) where did that energy go? Well a lot of it went to moving the piston! If we lived in a “perfect” world from the view of an engineer, all of that energy would go to the piston. In the real world, it did not, and that will be the subject of entropy.

Let’s take a step back though before getting into that, and play some more with our cylinder.

Last time, we wrote:

Heat is a measure of the amount of energy that went into raising something to a certain temperature. Heat is energy. Temperature is a manifestation of that energy that is different for different substances. Different items in thermal contact with each other exchange heat, until they come to the same temperature. Mathematically, a change in heat Q, is related to a change in temperature T, by the heat capacity of a substance.

From this point of view, temperature can almost be thought of as a measure of how much heat a substance has “free” to give up compared to something at a lower temperature. Let me please refine that. I wrote last time about all sorts of different possible motions on the microscale, let me just call it waggling here.

If I have something hot touch something cold, the hot thing’s atoms and molecules are waggling a lot more than the cold things atoms and molecules are. On a microscopic scale, the hot thing causes the cold thing’s bits to waggle more, by knocking into th cold things and shaking them up, or spitting of photons which the cold things catch, while the cold thing causes the hot things bits to waggle less by accepting energy from them. If the two items are at the same temperature, they both internally waggle exactly as much as their given heat capacities demand they do for that temperature. Putting them in thermal contact with each other causes neither one to change. But, if one is hotter than the other, then the hot one will cool and the cool one will warm – until they come to the same temperature.

So let’s apply this idea in the real world. Suppose I have a box. Inside the box is a cylinder with a piston that is partially filled with some fluid that has a low specific heat and the piston is compressed half way. I move the piston up. As I do this, the temperature of the gas in the piston goes down. Since the gas has a low specific heat, it goes down a lot. Look at the first law, and the previous discussion of temperature to convince yourself this is true. How much heat… PdV… Now the air in my box is at some warmer temperature than the gas in the piston and that air warms up the piston and cools a bit itself in the process. Heat went from the air in the box to the gas in my expanded piston. Energy is conserved, more heat now “lives” in the gas in the piston than it did before.

Now for the clever part…

If I compress the piston now, the gas has more internal heat than it did before and in the compression, it gets much hotter than it was before, but this time, I don’t let it sit there and exchange heat with the air in my box. Rather, I open a valve and send the gas out to a long tube outside of the box. It is happy to go, since it is at high pressure and squirts right out! The gas is now in the long tube and because of the compression, is hotter than the outside air. There is a lot of surface area over which to exchange heat, and remember that the gas or fluid involved has a low specific heat, so it gives up heat quickly and equilibrates to the cooler outside temperature quickly. We just pumped heat to the outside air! Once it has cooled, the piston sucks the now cooler gas back inside to start the process over again.

This is how a refrigerator works. If you don’t believe me, check the back of your fridge. The back is certainly hot (that is where that long tube is!) and it is both radiating heat and having heat carried away by conduction and convection with the air in your house. In this case, I am supplying energy to use the piston to act on the fluid and move heat around.

A common canard amongst people who deny AGW, when current shifts occur and the Atlantic thermohaline pump is affected, is “how can you make something hot to make it cold?” Well there is one example of how, and almost everyone in the Western world has seen it in action in their very own home. Heat pumps are real things.

If I run the process in reverse, and use energy stored in the fluid to move my piston, I have an internal combustion engine. In that case, I take the energy stored in the chemical bonds of the fluid, release it (with a spark plug and an oxidation reaction) and push the cylinder to do work on something else, like turning wheels.

In all cases though, the First law is just telling me that in the course of moving all of this energy around, I am never getting more out than I put in to begin with.

There are more details for those who are interested of course. I haven’t really gone into changes in pressure and volume and Carnot Cycles and all of that. I leave those topics to those who wish to go further on their own.

But all is not perfect. All of the heat does not go into pumping the piston. I have to spend more energy than the first law (if naively applied) might lead me to believe to get what I want. This is the second law. You can’t break even.

Another statement of the second law which is equally useful comes from Kelvin.

No process is possible whose sole result is the absorption of heat from a reservoir and the conversion of this heat into work.

Some of the heat went into warming the walls of the piston, or into friction with the piston and the cylinder wall. That isn’t doing me any good. It is lost energy. Entropy is the measure of this.

Lots of people have heard that entropy is some sort of measure of disorder in a system. When pressed further as to what that might mean, they wave their hands. This does not stop them from saying something like well entropy always increases according to the second law, evolution goes from lower to higher order and there must be a contradiction!

We are going to tackle that nonsense right now. Not only did they misstate the law, entropy increases in a closed system – the closed part is important! – but, they have no clue what it is in the first place.

First, let’s talk about what entropy is.

Consider a system with a lot of small parts – like any macroscopic thing you have ever encountered, since it is made up of atoms and molecules. Consider every possible way you could rearrange those parts, or every different possible way those parts could be waggling or exchanging heat. Of all those possible ways it could be or things it could be doing, only some of them are doing work for you, or retaining a form you like. Everything else is something that it can also do, that is not useful to you. If the system can go into those states or modes, it will.

Let me give an everyday example. Why do your computer cords always tangle? You certainly laid them out straight. Well, the cords have some tension in them when you lay them out and they are going to coil and move when you set them down. Of all the possible ways the cords can end up, there is only one way for them to be straight, but many, many ways for them to tangle. As they coil up, the chances of them staying straight, when there are so many other ways they could move into a state of being tangled are almost nil. In this case, the tendency to get tangled is an example of entropy.

Entropy is in short, a measure of all the ways that a system can manifest its heat, energy or configuration in a way you do not like. In the case of an internal combustion engine, it is heat getting lost to friction and the walls of the cylinder rather than pushing the pistons. There are all sorts of mathematical ways to calculate this, and there is a way to say this firmly without any hand waving in terms of equations, but let’s leave that for those who want to dig deeper and stay purely conceptual.

The Second Law says that entropy will always increase in a closed system. A closed system is one which is not exchanging mass with an outside source. Closed systems are capable of exchanging heat with their surroundings though.

It is possible to fight entropy, but not to win forever.

If you are taking in energy, then it might be possible to use that energy to fight entropy and put things in the order you desire/need etc. And it might be possible to impose a certain state at the expense of another.

As an additional thought:

Don’t let the language of desire or need put you off. You want an efficient engine; you do what you can to minimize losses to entropy. This can either be a process done by an engineer, or it can be done by natural selection. A better heart, for example, is a survival advantage. You also “want” for instance, to maintain your own cellular structure, so you take in energy and material to do so.

So consider the following example of an isolated system: you, and Bessie the cow. Isolated systems do not exchange mass or energy with the outside world. And, this is a subset of the closed system of you, Bessie, the plants Bessie eats and the Sun. Your cells are undergoing normal wear and tear – going into configurations that you would not want, because if they get too messed up you die. Fortunately, you have all kinds of mechanisms to correct this, if you give them energy to do so. You make Bessie into steaks and eat her. Your entropy went down, but hers went way up! Getting sliced into steaks, chewed up and digested is unlikely a configuration she likes! Total entropy in the system increased.

Where does the energy ultimately come to fuel Bessie and almost everything else? The Sun! But as the Sun burns, its entropy is going up! In the closed system of the Earth and everything on it getting power from the Sun, the total entropy is still going up all the time as the Sun burns. One day, it will burn out.

Let’s take another example. Back in the day, people used magnetic tapes and disks to store information. Little magnetic crystals would be put into either an up or down configuration. These were little magnets and by scanning them with the right electronics, the changing magnetic fields could be converted into changing voltages that were then read by a machine or converted into a signal, or broadcast on a speaker. That part doesn’t matter. What matters is that the more you used them the more they might wobble out of place. Eventually bits of data would be lost here or there, or your tape would sound more and more fuzzy. This too is a measure of entropy.

To take it further, suppose you went to copy any stream of bits, as in a 0 or a 1, and you have a really good machine to do it. There is only one configuration of those bits which is the information you want. For each bit that gets recorded, there is a chance of a bit of the information being recorded wrong – as something different. Out of 10 bits, there is only one way to have whatever your 10 bit message was, but there are 1023 ways for it to be something else. If transmission were completely random, then you would have less than a one in 1000 chance of getting the right message. But it isn’t completely random, any given bit is most likely to be copied correctly. However, over multiple copies, errors will and must occur eventually. Entropy becomes a measure of how easy it is to get into one of those other states.

So let’s say that you have a really good machine to copy your information and you build the mechanism so it is hard to get a bit wrong. There is still some chance that it will mess up somewhere. Eventually, a copy will have a bit wrong. Eventually, some copy of that will have two or more bits wrong. This is entropy increasing.

Here we come to the part where we nail the evolution deniers hard. DNA is nothing more than a coded string with many bits of data. We have really good cellular mechanisms for copying it from one generation to the next. But what is a mutation if not a change in the DNA? Eventually over time, all sorts of errors will creep in. If those “errors” end up being beneficial, then they get copied to the next generation that makes more babies. If not, they die off. In fact, on the level of encoded information, evolution is exactly an example of entropy increasing.

For those that wish to dig deeper, I invite you to go into Shannon’s Law.

Next up, the third law, absolute zero and you can’t leave the game.

LudwigVanQuixote
Science • 2 weeks ago • Clicks: 24 • Views: 274

This is the first of what I hope to be semi-regular science discussions on topics that are of interest for their own sake, and that get frequently abused by various voices in the political media.

Thermodynamics is frequently dragged out by various hacks and pundits to mislead people because it is almost perfectly suited to do so. It is a very old and established theory. Many have heard the word thermodynamics. People know that it is something legitimate that scientists worry about. In fact, it is old enough that it is stated in terms of laws. People who do not understand what the word theory means in a scientific context, and who sew confusion by claiming something is “just” a theory, in the ordinary sense of the word, happily abuse misstated laws. Surely laws have more weight! There is a finality there that can be used to impress a rube. The fact that a scientific law is simply an archaic term for a very well established theory is lost on them, and the propagandists exploit this missunderstanding ruthlessly. Another reason that thermodynamics gets used as such a go to for spreading confusion is that unlike relativity or quantum mechanics, there really are no good books about it written for a general audience. There is a lot less chance of finding someone who is conversant with it at even a basic level. This may be because, thermodynamics contains an elegant mathematical discussion of how everything physical – even the universe itself – eventually dies, runs down, burns out or simply breaks or decays. That simply isn’t sexy.

An old joke about thermodynamics is that the laws of it are:

Life is a poker game that you must play.

You can’t win.

You can’t break even.

You can’t leave the table.

As these lectures move forward, it is one aim to show just how clever, true to the physics and apt that joke really is.

Thermodynamics encompasses or influences almost everything. It is a fundamental topic. Because of that, it can easily be pointed at almost any scientific discussion. Whether or not it is pointed correctly is another matter because thermodynamics is difficult, counter intuitive, abstract and very demanding. Very few people have any clue whatsoever about what it actually says, and further, because it is so abstract, a slam dunk argument, is easily deflected in a debate by a charlatan, because it is all so many big, misunderstood, and misapplied words to both the fraud and his misinformed audience. With that, I hope to start clearing up some of this mess, and giving a basic feel for what this is all about to my readers.

I do hope though that even now, my reader will see quickly that since thermodynamics is something that every physical scientist has to learn and is so central to so many different topics, that the idea of some political hack, preacher, or barnyard “genius” coming up with an obvious proof that some well established theory violates thermodynamics is ludicrous at the outset. It’s rather like claiming that the proof of a well established mathematical theorem failed to notice an error in addition, and none of the mathematicians noticed. Some fool spouting off on a blog or on Fox news claiming that scientists got something wrong thermodynamically assumes that somehow the entire rest of the scientific community missed a very glaring and basic error – yet, it was not hidden to the “scientific prowess” of that journalist, politician or lobbyist (who personally couldn’t tell you the Pythagorean Theorem) and now he is going to show those smart fellers up!

Before even getting into thermodynamics proper, we have to lay some ground work. I wish to discuss heat. Heat is not temperature. We all say it is hot or cold outside, but when we do, we are not talking about heat. Science, in general, does not employ synonyms. If there are two different words, there are almost always two different concepts.

So what is the difference between heat and temperature?

We all have a sense of something being hot or cold. We know by touch, the difference in sensation of holding a glass of iced tea and a cup of hot tea. We know the difference, from our skins, between a blustery winter day and a summer scorcher. In some sense, temperature started as a way to standardize this difference in sensation. The astute reader should already notice that temperature can’t be something fundamental from weather reporting. If the concept of temperature were fundamental, in the sense that it was all there was to say about it, 30 degrees outside would be 30 degrees outside, you would not need to discuss wind chill or being in the shade. For those who are looking ahead, the point is that when we say that there is a wind-chill of 10 degrees, we mean that wind convection and conduction is carrying away a certain amount of heat from you, and in response, it feels colder.

It was discovered that certain metals and compounds expanded or contracted depending on whether or not they were hot or cold. Mercury placed in a glass cylinder expands or contracts depending on the apparent temperature. The thermometer was born and it was a handy way to say in numbers, this or that is hotter or colder, and by how much. But there was a big problem. Say I had a pot of alcohol and another part with an equal volume of water. Say I put them side by side over the same low fire for the same short period of time. They would always be at different temperatures. They would boil at different temperatures too, but the key observation is that it would take “more fire” specifically, more time for the fire to transfer energy, to heat up the water to the same temperature than it did the alcohol. More investigations showed that pretty much every different material would get warmer or cooler at different rates and with different amounts of work done to heat them up. Work in this case being how long you kept the thing on a burner but, for certain, that is just one example.

So you might conclude the temperature is meaningless. But it isn’t. If you have a room at a certain temperature, pretty much everything in it, will come to that temperature, no matter what it is made of, if you give it enough time to equilibrate. We have a conundrum. On the one hand, the amount of work I need to do to change the temperature of different things is different for every different substance. So you might think, that what we really need to worry about is the work needed to heat something up, because what temperature “means” in terms of how much energy you put into heating it, to one thing, is not what it “means” to another. On the other hand though, if you give a collection of things, which are in thermal contact with each other, enough time – even though they are all at different temperatures and made of different stuff, they all come to the same temperature. So temperature seems to be pretty important after all! What is going on?

I have already hinted at part of the answer here.

Heat is a measure of the amount of energy that went into raising something to a certain temperature. Heat is energy. Temperature is a manifestation of that energy that is different for different substances. Different items in thermal contact with each other exchange heat, until they come to the same temperature. Mathematically, a change in heat Q, is related to a change in temperature T, by the heat capacity of a substance. In the simplest case, dQ = CdT, where C is a constant called the heat capacity. Later on, we will take into account things like pressure, molarity and temperature. We will then talk about the specific heat at constant pressure for example. Specific heat is heat capacity per unit mass.

As always, it is good to attach these concepts to every day experience. Anyone who has ever made tea, or noodles, knows that it takes a long time to boil water, and that hot water stays hot for a long time. We say that water has a very high specific heat. This means, that it takes a lot of energy to raise its temperature, and that once raised, it has to lose a lot of energy before it can cool. That is what a large value of C means.

So let’s refine this a little bit. To help us do so, It is helpful to remember that all matter (that we encounter on a regular basis, at least) is made of atoms and molecules. Neutron stars, and other exotic things like dark matter, obey thermodynamics also, but let’s not go far astray.

Atoms and molecules are not static things. Let’s imagine the simplest case. In a tank of monatomic gas, like say a tank of neon, the atoms of the gas can be thought of as little hard spheres. This takes away potential complications due to chemical interactions, or any funny business with quantum mechanics. Noble gasses, (neon is one of them) have nice filled shells. We don’t need to worry about them pairing up and taking energy to make molecules. When they bounce off of each other, to a very good approximation, it is like billiards (all of those things can be taken into account, but basics first). Even so, those atoms are not staying still. They are all moving at very high speeds and constantly colliding with each other and the walls of the tank. In fact, pressure is a measure of how much and how hard they are hitting the tank.

Microscopically, this will give an insight into what is going on. First off, you might ask, how fast are the Neon atoms moving? It would make sense that the faster they were moving, the harder, they would hit the walls of the tank, just from simple conservation of momentum. This is entirely true. It turns out, that in this case, the temperature of a gas, (and hence the heat contained by a gas) is nothing more than a measure of how fast on average the gas atoms or molecules are moving. Heat is energy. In this case, it is nothing more than the average kinetic energy of the gas. If this is true, you would expect that if I heated a tank of gas, the pressure would go up, because then the individual gas atoms would be moving faster, have more kinetic energy and then smack the walls of the tank harder. Of course, this is exactly what happens. If that heating were caused by a rapid chemical reaction that also converted a solid into a gas, this is the idea behind a gun! We see already, that temperature, pressure and heat are all related to each other, even in the simplest case of a tank of non-chemically interacting gas.

If this picture is correct, you would expect, that since energy is conserved, that if I allowed gas to escape my tank, it would carry heat away and that since temperature is related to heat, the temperature would go down. Anyone who has ever used an aerosol spray can has noticed that it gets cold when you use it. Don’t believe me? Try it with a can of shaving cream, or air freshener or whatever you have handy that won’t make too much of a mess. Spray it a bit, and it will get colder. Energy is always conserved! The tank gave up internal heat to the world outside the tank.

In general, though, internal heat is more complex than just atoms moving in a tank of gas. Consider molecules. Molecules are not the static things that you might imagine from chemical diagrams. Depending on the structure of the bonds and the molecules themselves, they may vibrate, flap, or even have little bits that rotate like propellers (like the case of a methyl group attached to a larger molecule). Further, different bonds can be exited into different energy states and give off light. All of those motions take energy to start. All of those motions together are what make for heat. Since different substances have different configurations on the microscopic scale, there are many different ways for a given substance to take on energy and hence heat. This is ultimately why different substances can sit on a flame for the same period of time and yet have different temperatures. There are simply more or less ways for a given molecule to take in energy than some other molecule and it may take more or less energy to excite a certain motion in a molecule or excited state from one substance to the next.

This brings me to how heat gets transferred. There are three mechanisms. They are conduction, convection and radiation.

Conduction occurs when you have direct physical contact between substances at different temperatures. For example, a piece of metal is put into a flame. The atoms of the flame (gas so hot it gives off light, and that is radiation!) literally have more kinetic energy in overall movement as well as whatever modes of vibration. Those hot atoms bounce into the cold ones of the metal and start them wiggling (as in having whatever exited modes of vibration). Those metal atoms are bound to their neighbors and start them wiggling and so on down the line.

Convection happens when there is a mass of hot material carried by an overall flow. For example hot water can be carried downstream.

Radiation, in this case, is giving off light. This happens because the substance is hot enough to excite bonds into higher energy levels which then radiate out that energy as photons. Think red hot metal, or picking up a person with an IR scanner.

Quick note, from this, we can already debunk one bit of pseudo-scientific nonsense. The Earth can only, as a whole, cool by radiation. Why? Because space is a vacuum, and you can’t have conduction or convection in a vaccum. Conduction and convection both require a medium to exchange heat.

We are now ready to state the first law of thermodynamics! Are you ready for it?

It is no more or no less, than energy is conserved. In other words, you can’t win. You can never get more energy out of a process than was put in.

Specifically, dU = dQ – dW.

In other words, the change in total energy of a system is the change in heat of the system minus the change in work done by that system on something else.

Our next lecture will go into some examples of this and build up to the second law.

LudwigVanQuixote
Science • 3 weeks, 6 days ago • Clicks: 18 • Views: 240

I really am going to start up long discussions about scientific topics themselves. However, I think it is very necessary to set up some more foundation before going into such things.

Much of the charlatanism of the politicized science “debate” rests on exploiting common misunderstandings of what science actually is, how it works and the words scientists use. It creates an atmosphere of willful confusion and misdirection.

Science has many terms, that when used, mean very specific and carefully (frequently mathematically) defined ideas. Precise language is essential because without it, one can quickly lose the point, or be led to understand something completely different than what is being said. Scientific writing does not have very many synonyms. If there are two different words, they almost certainly represent two different concepts. Unfortunately, everyday communication is rarely so technical. Much unnecessary conflict between scientists and everyday people comes from the misuse of technical words by confabulating them with their everyday meanings. Consider the following (painfully inadequate to a scientist) definition provided by a popular dictionary.

Science is, according to Webster’s New Collegiate Dictionary: “knowledge covering general truths of the operation of general laws, esp. as obtained and tested through scientific method [and] concerned with the physical world.”

So science does not address specific truths and specific laws as well?

What is this scientific method anyway? Worst of all, is the phrase especially as obtained by the scientific method, because this implies there is at least some science that was not obtained and tested through the scientific method. I don’t recommend suggesting this definition to a scientist any more than I would recommend suggesting that some pork is kosher to a rabbi.

Definition: Science means the body of knowledge about, and consistent models of, natural phenomena as only obtained and rigorously tested through the scientific method, or the act of obtaining such knowledge or creating such models through the scientific method.

This immediately implies that something which is outside of the scientific method is automatically neither science nor scientific. Now, “not scientific” does not necessarily mean bad, wrong, useless or untrue. For instance, the notion that one should treat animals compassionately has nothing to do with the definition of science, but has everything to do with ethics. Even though Shakespeare’s sonnets are not taught in Physics 101, they do beautifully express how some people feel about their spouses. On the other hand, “not scientific” means just that, and it can cut two ways. If an idea can not be approached by the scientific method, then it can never be either supported or denied by science.

Definition: The scientific method is the four step process by which the scientific community collectively gathers and analyzes observations of the natural world in order to create tested, consistent, predictive and falsifiable models of natural phenomena. Further, this process demands that the final arbiter of any scientific dispute is observation.

In other words, if you believe that God made the universe, then the universe He set up, and hence Him, Himself is the final arbiter.

Before getting to the four steps, it is important to note that nowhere in this definition is there any room for democracy, personal preference or being “even handed” with the other side. In a scientific debate, once sufficient data comes in, there is always a winner and a loser.

Amongst professional scientists, these debates generally take two forms. Firstly, “does this really mean what you think it means?” Secondly, “did you really see what you think you saw?” Once those debates are settled, you have clarity. Both debates are closed by more data and/or better analysis. Eventually, the evidence mounts and consensus is reached. An open debate implies that there is, as yet, insufficient data, incomplete analysis or both. The final word always goes to the physical evidence itself. There is no “second place.” This is as it should be. Good scientists do not say that the universe is some way that it isn’t to please anyone, ever.

The four steps:

1. An interesting phenomenon is observed and described.

2. A hypothesis is formed to explain the phenomenon. A hypothesis usually takes the form of positing: a new or refined picture of some situation, a causal relationship or a mathematical description. It is an “educated guess.” It is patently not a theory.

3. If the hypothesis actually reflects what is going on, it will not contradict other observed phenomena and the existence of new phenomena will be predicted as consequences of the hypothesis. These consequences are identified and searched for. In this step, the new predictions will be the subject of experiment. If the universe does not comply with the prediction then, the hypothesis can not be the correct explanation.

For example, if your hypothesis is that the Earth is round, it is implied that one could go west from England, go all the way around the world, and eventually come back to England from the east. The experiment would be to get on a ship or a plane and try it. If you fall off the edge, then the hypothesis was wrong. This is what we mean by falsifiable.

4. Evidence mounts. Experiments and analyses are done by multiple independent observers. If the predictions of the hypothesis keep coming true and the hypothesis continues to be consistent with observed phenomena, it starts to become accepted by consensus as a correct model of the physical world. If new evidence comes in, that challenges the model, the model is either refined to incorporate the new evidence, and thus, once again, be consistent with known observation, or the model is completely rejected and a new hypothesis must be started back at step one. The latest, refined version of the model, which is consistent with all tested predictions and available observations, is called a theory. Theory does not mean here what it does in everyday use.

Please note that at each step, there is a connection with the real, observable, physical world. Many people have the false conception that somehow science is disconnected from reality. This could not be further from the truth. All those people are saying is that they don’t get it and that they want to sop their egos by pretending that science isn’t important.

Once something has been established as theory in the scientific sense, it is as true as the entire scientific community can tell, to a standard far more strict, than any court of law. The whole point of the independent observers doing independent trials is to remove human error and bias from the process. If 1,000 people show that something happened in 1,000 different ways, what are the odds that all the 1,000 observers were biased and that all of the 1,000 experiments were flawed?

Some theories, once established, go for centuries without needing to be refined. By that point, the evidence literally comprises millions of observations and man-years of work. Refining does not mean throwing out either. For instance Newton’s theory of gravity was refined by Einstein’s theory of gravity. However, Einstein’s theory contains Newton’s theory, and after over 300 years, Newton’s math is still all that one needs to put a satellite into orbit or a man on the moon. As another example, many think that the Earth is round, means that the Earth is a sphere. For many problems, this is a perfectly acceptable model. In reality, spheres don’t have mountains or valleys, but the Earth’s shape is still round, if not a perfect sphere. “The Earth is round” is an example of a valid scientific theory.

One of the most hurtful things that can be said to a scientist is to try to dismiss a theory in the scientific sense of the word as “only a theory” in the common sense of the word. This statement not only demonstrates that the speaker has no understanding of how science works, let alone the scientific point they are about to get wrong, but implies that all those years of observation, careful work and painstaking analysis by diligent people meant nothing. It is as obnoxious as saying to a rabbi that “the Torah is just a story”.

LudwigVanQuixote
General • 4 weeks ago • Clicks: 6 • Views: 69

This is for all of those who think that somehow, Fatah are the “nice” and “reformed” terrorists.

[Link: www.jpost.com...]

By KHALED ABU TOAMEH

09/29/2010 00:49

Former PA chairman issued instructions to terror group when peace talks were failing; Hamas leader makes revelations during university lecture.

The late Palestinian Authority chairman Yasser Arafat had instructed Hamas to launch terror attacks against Israel when he realized that peace talks with Israel weren’t going anywhere, Mahmoud Zahar, one of the Hamas leaders in the Gaza Strip, revealed on Tuesday.

“President Arafat instructed Hamas to carry out a number of military operations in the heart of the Jewish state after he felt that his negotiations with the Israeli government then had failed,” Zahar told students and lecturers at the Islamic University in Gaza City.

Zahar did not specify when and how Arafat instructed Hamas to launch the “military operations” – most of which were suicide bombings targeting Israeli civilians.

However, it is believed the reference is to Arafat’s response to the failure of the Camp David summit in 2000.

This was the first time that a senior Hamas official disclosed that some of the Hamas suicide bombings during the second intifada, which erupted 10 years ago, were ordered by Arafat. Until now it was widely believed that Arafat had only ordered his Fatah militiamen to carry out terror attacks on Israel.

According to various testimonies, Arafat ordered the armed wing of Fatah, Aqsa Martyrs Brigades, to launch terror attacks against Israel after he realized that the government of then-prime minister Ehud Barak was not going to meet all of his demands.

Zahar claimed that Arafat’s decision to negotiate with Israel was one of the factors leading to his “assassination.” He said the decision was a grave mistake and a tactical error on Arafat’s part.

Zahar urged PA President Mahmoud Abbas to pull out immediately from the talks with Israel.

He claimed that the PA’s security coordination with Israel has resulted in the elimination of a number of Hamas men in the West Bank at the hands of the IDF.

He added that Hamas now was better able to smuggle weapons and other military equipment into the Gaza Strip in preparation for the next confrontation with Israel.

Zahar said that a growing number of Palestinians were now convinced that the armed struggle was the only way to deal with the Jewish state.