godclouds said: So I have to make a presantation for chemistry class. I will choose the subject but I havent choose it yet. Do you know any subject that easy and easy to find gifs abou it. Could you recommend me?
If you limit yourself to things that are easy to learn enough about to repeat it half-convincingly to a teacher who will subsequently grant you a B+ out of a sense of obligation while sighing inwardly and mumbling under their breath about kids today who can’t learn or present anything without those fancy animated picture things, you will never learn anything truly worth learning.
I recommend trying to learn something about chirality, which is a very important concept in organic chemistry, and biochemistry in particular. In pharmacology, right- and left-handed molecules can have radically different effects. An interesting example is dextromethorphan, which is found in cough syrup sold over the counter in many countries, and which in larger doses has dissociative effects sometimes—by which I mean all the time—used for recreation, and levomethorphan, which is a scheduled narcotic for its potent opioid activity. My favorite part about not being a high school teacher who needs to give out B pluses while sighing inwardly and so on is that I get to talk about how to get high on cough syrup and the irony of scheduling one stereoisomer for its narcotic effects while selling another equally power mind-altering drug over the counter because in lower than recreational doses it happens to reduce coughing.
Chiral molecules are named for the way they rotate light. Prepare to have your mind blown by the mere fact that light can be rotated. In fact the polarization of light is a property to which we are as blind as someone who sees only black and white would be to color—note that I didn’t say color blind, as most color blindedness leads to an inability to distinguish only certain colors, most commonly red and green, not to the complete lack of color vision—but to the magnificent mantis shrimp, light polarized in different directions looks as different as light of different colors looks to us.
Chiral molecules are abundant in nature because life depends on carbon, which is tetravalent, meaning it has four free electrons available to bond with. Most biological processes depend on molecules of a particular handedness—one apocalyptic science fiction scenario involves all the biological molecules of the correct handedness suddenly—by an impossible mechanism which is hand-waved away by the author for the sake of the story—being turned into their other-handed cousins. Thus life as we know it on Earth couldn’t survive.
See what happens when you look further than what is easily available in GIF form? You just learned how to get high on cough syrup, that light can be polarized and that polarized light can be rotated and that many important medicines and biological molecules come in right and left-handed versions—frequently, but not always, on account of a “chiral center” around some carbon atom—and that the handedness is named originally after the direction in which they rotate such polarized light, and that the mantis shrimp can perceive this rotation, and in fact has vision superior vision to all of us. Oh, and how to write a killer science fiction novel.
I read through previous posts about temperatures and pressure and got to thinking about something I’d never considered: why Celsius? And what’s up with Fahrenheit, anyway?
Anders Celsius, the man behind the name, was born on November 27, 1701 in Uppsala, Sweden. Son of an astronomer and grandson of two, it’s unsurprising that he dedicated himself to higher mathematics. Before he created his famous temperature scale, he was involved in an equally interesting debate: the question of the earth’s shape. At the time, there was wide agreement among scholars that our planet is basically round: however, there was equal agreement that the earth was not a perfect sphere. The question was about the nature and degree of deformation from that imaginary ideal. Newton had calculated that our planet is flattened at the poles; as a consequence, a degree of latitude would be longer near the poles than at the equator. On the other hand, measures by the French astronomer extraordinaire Jean-Félix Picard indicated that the planet is more egg-shaped.
Anders Celsius helped resolve the dispute. The French Royal Academy of the Sciences sent an expedition to Peru, current day Equador, to measure latitude near the equator. Celsius suggested that another expedition travel to the Torne Valley, on the border of Sweden and Finland and north of the Arctic Circle, to take measures for comparison. Celsius imagined that this expedition, carried out in 1736-37, would be the final word in the dispute over the shape of the earth. Celsius couldn’t imagine, of course, that in 2014 we would all be carrying in our pockets navigation instruments based on measurements of our earth accurate to a degree only possible in his fantasies, anchored in satellite technology. Nevertheless, he makes the following prescient remark in his “Letter to N. N.,” a pedagogical brochure written to explain the purpose of his expedition:
My Lord might be puzzled that Astronomy, which claims to know the length, shape and size of planets thousands of miles removed from us, still does not know the size and shape of the planet they walk upon daily. But that is not so strange; because one who observes our planet from e.g., the moon, can much easier observe her figure; and on the other hand, that we know the moon’s shape.
If only you knew about GPS, Anders! I’m sure he’d be smiling. The Torne Valley expedition was led by Pierre-Louis Moreau de Maupertuis, the first director of the French Academy of Sciences, and it was a success. Their measurements and the measurements from Peru confirmed that Newton was right: we live on a spheroid flattened at the poles.
Onto the thermometers. In the 18th century, there were dozens of different temperature scales proposed and circulating in scientific circles. Newton had proposed a scale based on the fixpoints of water’s melting and boiling points. Celsius used a Delisle thermometer to make measurements. The deciding factor, as it often is, was scientific rigor. Celsius recognized that in order to create an international temperature scale, equal amounts of heat must measure out to the same number in Paris as it would in his hometown of Uppsala. He set out as scientists do, to separate variables. The ideal is to keep conditions exactly the same in all matters that could conceivably affect the result of an experiment except one. If you vary many different variables at once, you can’t separate them and find out which variable gave rise to the effect. So to measure temperature, you’d want every condition except heat to be equal. Celsius made rigorous measurements of how the boiling point of water varied with pressure. Thus the boiling point of water at a specified pressure would have to serve as the fixpoint.
Celsius fixed his scale at 100 degrees for the melting point of water and 0 for the boiling point.
Wait, what? Yes. Some early scales, such as Delisle’s, were reversed: the colder it got, the higher the temperature in degrees. Perhaps influenced by his Delisle thermometer, Anders Celsius also employed this reverse scale. His scale was quickly picked up and spread, but people such as Daniel Ekström, maker of Celsius thermometers, and Carl Linnaeus, the botanist, inverted the scale and gave us the familiar Celsius scale. Measurements on this scale were commonly referred to as “degrees centigrade,” but the International Committee for Weights and Measurements officially declared that the term to be used was “degrees Celsius”—in recognition of the possible confusion between temperatures and 1/100th of a degree of arc, a term also dubbed “centigrade.”
As for Fahrenheit, the scale was defined by two fixpoints: zero, the lowest temperature Daniel Gabriel Fahrenheit could cool brine, and a hundred, the average human core body temperature. Neither of these were rigorous enough, and today the scale is officially defined with reference to other temperature scales. That, perhaps, says enough, although cultural explanations would have to fill in the gap as to why a scientifically inferior—because it was lacking rigour—scale has survived in North America and to some degree Britain while most of the world has long since switched to Celsius.
Come the 19th century, the need for an absolute temperature scale became apparent. Lord Kelvin introduced the unit that was later named for him, the Kelvin, denoted °K, in 1848. It is based on the Celsius scale insofar as the temperature intervals are the same, but the zero point is instead defined as being absolute zero, the point at which all particles are at their lowest energy state, at which no further cooling is physically possible: -273.15 °C. 0 °K. Shortly thereafter, the Rankine scale was proposed, which takes the same approach, defining its zero point at absolute zero, but taking the intervals between each degree after the Fahrenheit scale, that is 9/5ths or 1.8 degrees for each degree celsius.
One could again turn to cultural explanations for why the Kelvin scale, which could be said to be scientifically superior to the Celsius scale, has not seen use outside scientific circles. I suppose in daily life the boiling and freezing points of water are more relevant to our interests than absolute zero, a physical curiosity that we never encounter naturally—even in deep space, the temperature is slightly above absolute zero. One thing we can say in the Kelvin scale but not in Celsius or Fahrenheit is that twice the temperature actually means twice the thermal energy. 20 °K really is twice as hot as 10 °K, which is not the case with 10 and 20 °C.
A little funny aside that I found while researching this article: remember Linnaeus, the botanist? You might know him as the father of modern taxonomy, the classification of living things. A century before Darwin introduced his theory of evolution, which would give the right framework for such taxonomies, he gave us essentially our modern way of classifying plants and animals. One part of that method is the so-called type specimen: the particular sample of an animal or plant that has been studied and fixes a name to that particular species. And the type specimen of Homo sapiens? Carl Linnaeus.
timelordtributedetectivewizard said: Can science answer moral questions?
A wise man named David Hume once wrote that, in all the moral systems he had observed, at some point the author proceeds imperceptibly from “is” statements, statements about how things are, to “ought” statements, normative statements about how things ought to be. But they never seem to add the necessary logical step between—how one goes from those statements about the natural world as it is, to the statements about how it ought to be. In other words, morality. What has become known to some as Hume’s Law states that one cannot logically derive an “ought” statement from a series of “is” statements.
This is a philosophical question, and as philosophers are wont to do, they still argue about it, almost three hundred years later. Some claim that Hume’s Law is false. They subscribe to a theory called moral realism. Others claim that it holds, and they are called moral anti-realists. This whole philosophical field is called metaethics, and concerns questions such as what moral statements really mean, whether one can derive normative “oughts” from facts about the natural world, and related issues.
Science is in the business of describing the world as it is. As such, scientists are rarely interested in questions about how it ought to be. Or they might be interested, but they can only come with proposals, not actual, logically deduced demands about how people should treat one another. That is philosophy, not science. Science explores and teaches us about how the world works, not about how humans should behave towards one another.
In my personal opinion, science can certainly explore moral questions, but cannot conclusively answer them. We can do polls about what people think, but is it given that what the majority thinks is true? In any other field, one would say no. When people thought the world was flat, or that the Earth, not the Sun was the center of the universe—later, of course, we realized that the Sun isn’t even the center of the universe, which has no center, but merely the center of the solar system, but that’s a tangent—would that majority opinion make it true? No.
Game theorists and others try to model how one can optimally behave in various situations. But if taken as a moral theory, that could easily lead to egoism.
Some claim that what is natural is right, but they also skip the necessary logical step between “is” and “ought”. Rape happens in nature. Does that make it right? No. That is sometimes called the naturalistic fallacy.
This is a super complicated issue that has been debated since Socrates. If you are interested, you can read Plato’s dialogue Euthyphro. Or you can read about the is-ought problem on Wikipedia. The best source, however, is the Stanford Encyclopedia of Philosophy, which is a free encyclopedia peer-reviewed by philosophers. See here, here, here and here. But the Stanford Encyclopedia is rather dense and technical, and perhaps hard to read if you have no previous experience reading analytic philosophy.
Personally, I subscribe to a theory called moral quasi-realism, which was inspired by Hume and by Ludwig Wittgenstein and developed by Simon Blackburn. Blackburn has also written some books aimed at introducing people unfamiliar to philosophy to the field. Quasi-realism allows you to make moral statements without betraying Hume’s Law, but admittedly they have less force than if they could be claimed to be grounded in science.
In general, I have to say this is a very complex question to answer. It’s hard to answer properly without getting too technical, and I think most of the readers of this blog would lose track or patience or get bored quite quickly if I really got into it. Not because they’re dumb, just because this is Tumblr, they are unfamiliar, it’s technical and they might just want to look at pretty pictures or hear the latest in science explained in an understandable, but not dumbed-down way. That is my goal with this blog: to bring science to the people in a way that neither betrays the science by explaining it with half-baked metaphors or overhyping findings which are really just small developments in a field. But also to make it readable and enjoyable for as many people as possible.
Science is fantastic, people! It’s not just pretty pictures of galaxies or neurons or puppies transplanted with genes so they glow in the dark.
But to conclude: No, science can’t answer moral questions. Only explore them.
The Golden Rule, advocated by such luminaries as Jesus and Buddha, is still a good rule of thumb. It’s not scientific, it’s just a basic test to see if you’re being an asshole or not.
This is not scientific advice grounded in peer-reviewed journals, but it’s still damn important: be kind to one another, and as long as people are not hurting anyone else, tolerate them, whether they have the same skin color or the same politics or religion or musical tastes as you or not.
The Galle crater is a Martian crater that happens to look like a smiley face, due to the position of a curved mountain range.
Someone made a good point about our previous post about carbon dioxide melting on Mars. At normal pressure, or the very low atmospheric pressure on Mars (less than 1% of the average at sea level on Earth), dry ice does not melt into liquid. Instead, it sublimes. Sublimation is a word for the phase transition where a solid bypasses liquid entirely and becomes gas. This is what gives the familiar smoke effect you get when you expose dry ice to air. You would need a pressure of over 5 atmospheres, that is five times the pressure at sea level on Earth, or about a thousand times the average pressure on Mars, to create liquid carbon dioxide. Sublimation also occurs to a certain extent to water ice on Earth.
The point at which dry ice sublimates at normal pressure is -56 celsius, which means when the temperature goes below this, the opposite transition, from gas to solid, which is called deposition, occurs. Thus “melts” was not the right word to use in the previous post. This also gives a measure of just what spring on Mars means: the dry ice cover starts melting, sorry, sublimating when the temperature goes above -56.4 C or -69.5 F. Talk about a chilly spring!
The atmosphere on Mars is about 96% carbon dioxide. About 0.1% is oxygen. For comparison, Earth’s atmosphere is about 78% nitrogen and about 21% oxygen.
The somewhat surprising fact, at least to me, that there’s only 21% oxygen in the atmosphere lead to the invention of carbogen, a mixture of oxygen and carbon dioxide. This mixture can be used to simulate the feeling of suffocation without actually suffocating, as the brain does not monitor the oxygen levels in the blood, but rather responds as if you can’t breathe if the blood carbon dioxide levels go too high.
It’s spring on Mars! Dry ice is
melting sublimating from the sand dunes to the North of the red planet. Image courtesy of NASA from the HiRISE camera onboard the Mars Reconnaissance Orbiter.
anothertragichero said: If a person dies quickly, would he/she feel the pain before death, or would they just die without feeling anything since it was so quick?
This is an interesting question. A good example of rapid death would be decapitation. For obvious reasons, one can’t do experiments on humans to figure out if they remain conscious for any period of time after having their head chopped off. Ranging back to the time of the French revolution, the heyday of the guillotine, there are anecdotes about people who apparently remained conscious and responsive to stimuli for a few seconds after the head was severed. There are also anecdotes about people who promised to give a sign after death to indicate awareness, and failed to do so. These anecdotes are impossible to verify. Decapitation or any other human death by extreme and rapid trauma has never happened during any form of scientifically controlled conditions. All we can say based on these anecdotes is that it’s possible that some people may remain conscious and feel pain for a short while after such a violent death. It’s also possible they aren’t, and it seems likely to be so for the majority of cases.
Rats are frequently used as model animals in research, so scientists have taken some interest in the question, do rats feel pain during decapitation? Is decapitation a humane way to sacrifice animals in research? Monitoring brain activity in rats as they were killed, researchers found no brain activity normally associated with pain in rats who were awake while their head was cut off. That suggests the rats were not in pain. Other scientists have calculated that it would take no more than 2.7 seconds for the rat brain to go unconscious from lack of oxygen. Given the nature of the trauma, more intense brain activity would be expected, which would use even more oxygen, and so unconsciousness would result even quicker. Taken together, these data suggest that rats, at least, do not feel pain after decapitation, and if they did, the duration of the pain would be no more than a couple seconds.
We can’t directly extrapolate to humans, but we can speculate. It seems likely that humans, too, go unconscious more or less instantly, at least in the majority of cases. Given the anecdotes, it seems possible that some may retain some kind of awareness for an instant after trauma, but the evidence is weak, so we’ll have to call it an open question. It’s certain, however, that the brain cannot function without oxygen, and that oxygen would run out in a matter of seconds after the supply was permanently cut off, so at the most, one could hypothetically feel a few seconds of pain. But then again the rats’ brain activity didn’t suggest pain. So the best answer I can give is that most people will probably not have time to feel pain before they’re dead, and it remains an open question whether some rare exceptions may retain a few seconds of consciousness, but if so they wouldn’t necessarily be in pain for that time.
guldguldguld said: I believe that we survive death. I have read that the soul is made of matter with a higher frequensy.
I have read that Yahweh created the world in six days, and on the seventh he rested. I have read that according to exact calculations of genealogies, this occurred less than six thousand years ago.
One should not believe everything one reads. This is not a question, but if it were one, it would not be well formed. Science, as far as it has been concerned with the matter of consciousness, has not found any evidence that consciousness continues past death. That is all we can say: nothing points to it. If by “the soul” you mean something that sustains our personality or consciousness, then the answer to your non-question is: no, that is not true. I can guarantee you the phrase “the soul is made of matter with a higher frequency” does not occur in any peer-reviewed scientific paper. Anywhere. Its likelihood of being true ranks up there with “the tooth fairy is made of matter with a higher frequency.”
It’s frustrating both for readers and writers of blogs that the reverse chronological nature of a blog buries so much good content. Few are willing to wade through vast archives that contain hundreds or thousands of posts. This blog has been growing at a huge rate, and lots of new readers may have missed a lot that they’d love if it were posted today. To make it easier to navigate the past, I’ve made two primary tags.
If you want to read more in-depth, long-form articles about various science-related topics, such as fractal dimensions, breaking the seal (re: peeing), which personality tests are bullshit, the strongest magnets in the universe, the unforgettable amnesiac or the pistol-dueling prodigy who died of gunshot wound at 20 and posthumously revolutionized mathematics, head over to the longer stories tag.
If you prefer to navigate the full archives, which include absolutely everything, at the time of writing 352 posts going back to June 2008, go here or simply navigate back and forth at the bottom of each page—but you probably know how to do that if you’re already on Tumblr.
Frozen animals in Nordland county, Norway
The first image shows a moose that drowned, then the ice froze around it, in Fauske, Norway.
The second shows a school of pollock that was chased towards the shore of the island Lovund by cormorants. Then the water froze so rapidly that the fish couldn’t escape, and became trapped in the ice. This picture was snapped by a man out walking his dog, and was quickly picked up by local mainstream and social media.