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Thursday, May 2, 2019

Why doesn't the crust of the Earth melt?

Why doesn't the crust of the Earth melt?


Why doesn't the crust of the Earth melt?

Posted: 01 May 2019 10:50 AM PDT

Dumb question: if the planet is filled with magma, why doesn't the outer crust melt into it? At some point deep down, melted rock is touching un-melted rock, so why aren't we all living on a Mustafar-like planet?

Edit: wow so many food metaphors! Thanks for the responses.

submitted by /u/sagressa
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Does being exposed to the common cold constantly like in a work environment strengthen your immune system?

Posted: 01 May 2019 09:21 PM PDT

Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science

Posted: 01 May 2019 08:16 AM PDT

Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Physics, Astronomy, Earth and Planetary Science

Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical /r/AskScience post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...".

Asking Questions:

Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions.

The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit /r/AskScienceDiscussion , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists.

Answering Questions:

Please only answer a posted question if you are an expert in the field. The full guidelines for posting responses in AskScience can be found here. In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for /r/AskScience.

If you would like to become a member of the AskScience panel, please refer to the information provided here.

Past AskAnythingWednesday posts can be found here.

Ask away!

submitted by /u/AutoModerator
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Why is Saturn the only planet in the Solar System to have a stable polygon shaped (hexagon) storm?

Posted: 01 May 2019 08:21 PM PDT

As far as I know, storms on other planets can be unpredictable, but what makes those storms last for centuries forward, especially Saturn's special hexagonal storm on its north pole?

submitted by /u/Skelyro
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Do animals have a sense of "good" smells and "bad" smells like humans?

Posted: 01 May 2019 08:35 PM PDT

Do animals (dogs, chimps, etc) find things that humans usually find pleasant to smell, also pleasant? (cologne, flowers, perfume etc.)

submitted by /u/m-a-k-o
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How do oil companies know where to drill for oil reserves?

Posted: 01 May 2019 11:33 PM PDT

How fast does something have to travel in earths atmosphere before it begins to heat up?

Posted: 02 May 2019 02:47 AM PDT

When I hold my hand out of a car window it gets colder so I was wondering how much faster something would have to travel before it heats up like objects from space do when entering the atmosphere.

submitted by /u/Voltaire1778
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What are the deternining factors for how much scar tissue a wound will grow?

Posted: 01 May 2019 07:04 PM PDT

How can we know half-life without observing nuclear decay rate?

Posted: 01 May 2019 10:48 PM PDT

From Nature: Dark-matter detector observes exotic nuclear decay

This article describes how scientists just observed a nuclear decay from Xenon-124 for the first time ever. They then give the half-life of this isotope at a trillion times the age of the universe, or 1.8 × 1022 years.

How is it that they can arrive at a number for the half-life if we can never measure the decay rate experimentally? Why isn't more than a single data point necessary for what they call "statistical" uncertainty?

submitted by /u/slushpilot
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How do anthropologists and paleontologists clarify that a discovered bone is from a separate pre-modern species and not just an old bone from a modern species that had a physical abnormality?

Posted: 01 May 2019 05:26 PM PDT

Why does the gulf stream make the temperatures of western/northern europe so moderate yet doesn't seem to have a similar affect on much of the east coast of the US?

Posted: 01 May 2019 08:40 PM PDT

Do our taste buds react differently to tastes as we age?

Posted: 01 May 2019 02:21 PM PDT

Not sure if this is the right subreddit to ask, but anyways, do our taste buds react differently as we age?

I remember loving chocolate so much when I was young, but now I do not like chocolate, nor do I crave it.

Same thing goes with foods like Bell Peppers. I hated them so much as a kid but now I love them, cooked or straight from the fridge.

submitted by /u/TacoJones2
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How does a child have a different blood type from its mother? Doesn't it get the blood through the umbilical cord?

Posted: 01 May 2019 08:16 PM PDT

Will the total amount of radioactive material in the universe decrease over time?

Posted: 01 May 2019 04:03 PM PDT

Since all radioactive material has a half life, shouldn't that cause the total amount of radioactive materials to decrease? For example: In 5730 years, will the universe only have half as much carbon-14?

submitted by /u/dashwsd
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Now that the Xiahe mandible has been identified as denisovan, what does it tell us about denisovan's appearance/anatomy in comparison to modern humans?

Posted: 01 May 2019 03:42 PM PDT

Does it tell us more about their skull shape?

Also, I've always heard speculation that denisovans are somwhat larger than humans, due to the size of their teeth in comparison. Has this been confirmed or contradicted by this revelation?

submitted by /u/TheDwarvenGuy
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Could we have a FinFET tranistor with 4 control surfaces rather than 3?

Posted: 01 May 2019 11:05 PM PDT

Here a "control surface" means contact between the gate and the source-drain circuit.

My understanding is that FinFET has an advantage over previous transistors because the raised gate now surrounds the path of the electrons on three sides, whereas previously it only had contact with one side. Having more contact area allows for greater control and thus less leakage, which can compensate for decreased control area as the length of tranistor shrinks.

If the gate entirely wrapped around the source-drain path, wouldn't the extra side reduce leakage? Is this impossible because one side needs to be the silicon substrate, or is it just infeasible with current manufacturing techniques?

Bonus question: Since going from 1 side of contact to 3 sides of contact between the gate and the circuit gave substantial improvements, would adding another side be a minor improvement or would it have disproportional benefits. e.g. a 4th side is only a 33% increase in contact area, but this might reduce quantum tunneling by 50%.

submitted by /u/Bananacity
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What component in drowsy drugs makes you drowsy?

Posted: 01 May 2019 07:05 PM PDT

How the human body chooses an energy source? (in other words: how it decides when to use either lipids(fats) or sacharides (glucose, glycogen...?)

Posted: 01 May 2019 11:58 AM PDT

Reading a Patent about aging spirits, it mentions a compound called m-2-gallic acid, what is it?

Posted: 01 May 2019 05:27 PM PDT

Okay, so I am reading this US Patent for accelerated aging of spirits, and in it the inventor mentions that oak bark contains a compound called m-2-gallic acid (amongst other tannins). He also mentions that this m-2-gallic acid can be divided into "2 particles" of gallic acid, indicating it's a dimer of some sort?

What is m-2-gallic acid? Does anyone here know? I have been searching google for about 30min now trying to figure out what it is, but I can't find any reference to m-2-gallic acid anywhere via google.

Could it be as simple as 2 gallic acid molecules bonded at their meta- positions, making it digallic acid (m-digallic acid)? But they made an error in naming it when writing the patent?

Any help would be appreciated.

If you want to read the patent, here it is. The m-2-gallic acid part is on page 4 of 6, and starts around line 35 (#s in middle of document)

US Patent on Google

submitted by /u/adaminc
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Why does water have a high freezing point compared to its parts?

Posted: 01 May 2019 08:58 PM PDT

Water's melting point is 0° C. Yet hydrogen and oxygen's melting point is super duper low. Why is this? Please explain!

Thanks!

submitted by /u/TerraWarriorPro
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Can and How do submarines 'float' still in the water without sinking further or going up further?

Posted: 01 May 2019 11:59 AM PDT

I need to make a small submarine for a project. It can already float on the water, sink and go up thanks to the Archimedes' principle, but I can't get it to be still on a certain depth. Does it have to something with Fp and its buoyancy Fa when equal in size. (like when floating on the surface.) If you can, linking your sources would be very helpful.

submitted by /u/ASnowyBird
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Wednesday, May 1, 2019

Why does beta plus (β+) decay happen in proton-proton chain reactions; why don't the two protons just form helium instead of deuterium?

Why does beta plus (β+) decay happen in proton-proton chain reactions; why don't the two protons just form helium instead of deuterium?


Why does beta plus (β+) decay happen in proton-proton chain reactions; why don't the two protons just form helium instead of deuterium?

Posted: 30 Apr 2019 06:26 PM PDT

Is there any medium that sound travels through faster than light can?

Posted: 30 Apr 2019 10:22 PM PDT

I learned recently that a team of scientists (lead by Lene Hau) managed to slow light down as slow as 38 mph using a supercooled medium.

I was wondering if there is anything out there that sound can travel through faster than light can. Or would the properties required for such a material make it unable to propagate sound?

submitted by /u/Toymos
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Did the asteroid impact that killed the dinosaurs significantly reduce the air pressure on Earth?

Posted: 30 Apr 2019 11:12 PM PDT

As i understand it, the impact blasted a significant amount of the atmosphere into space. Would sea level pressure have noticeably decreased, if only for a few hours?

submitted by /u/Matt32145
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A picture of a clear blue sky has greater entropy / information content than a busy painting: true, and if so, how?

Posted: 01 May 2019 06:08 AM PDT

The professor had put up two pictures: One was the famous Song Dynasty painting Along the River During the Qingming Festival, full of fine, rich details; the other was a photograph of the sky on a sunny day, the deep blue expanse broken only by a wisp of a cloud ... The photograph's information content - its entropy- exceeded the painting's by one or two orders of magnitude.

Cixin Liu, The Three Body Problem (fiction)

So I've attended some lectures on entropy, but not being a physicist and never having to apply the concept, the counterintuitive parts of it always just escape my brain's long-term comprehension.

Is this passage correct, and what's the explanation that someone with a PhD in a lowly subject like biology could follow?

(I've found this attempt at a discussion, but the top explanation jumps straight to algebra, and none of the others are very fluent. Link also includes the painting in question.)

submitted by /u/Glaselar
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Does environment affect personality?

Posted: 30 Apr 2019 04:55 PM PDT

Let's imagine we have two identical worlds. Two earths.

Let's imagine that we place two newborns with identical families with identical traits, one on each earth, in the same town or city.

The newborns grow into young adults experiencing and seeing all of the same things as the other. They share the same exact environment.

Do they have identical personalities?

submitted by /u/DoodiePootie
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How is the placebo effect mitigated in experiments studying effect of meditation?

Posted: 30 Apr 2019 08:25 PM PDT

For the studies on effect of drugs, I can easily imagine it being done by some fake pills and stuff. But how are the control groups designed for studying effect of meditation?

submitted by /u/TraditionalCourage
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What is the difference between a magnetar and a millisecond pulsar?

Posted: 01 May 2019 12:55 AM PDT

Are the two interchangeable? Both spin many, many times a second and I assume both have very strong magnetic fields.

submitted by /u/Vorpal_Lacrimation
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Why does a gases Mach Number affect whether it’s velocity increases or decreases when entering a convergent or divergent nozzle?

Posted: 30 Apr 2019 10:47 AM PDT

I'm looking for an intuitive explanation. The math makes perfect sense to me but I'm trying to get a better feel for why it happens. It must have something to do with whether or not a pressure wave can propagate through the gas, but I can't quite put my finger on why that would make a difference.

submitted by /u/bnpm
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Some moons are coplanar and some are not, what makes some of these moons non-coplanar?

Posted: 30 Apr 2019 08:02 PM PDT

Is it planetary impact, or gravitation from other nearby moons? Or something else?

submitted by /u/ENP2900
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Why is mortality from measles in the Philippines so high?

Posted: 30 Apr 2019 02:45 PM PDT

Hello. I am not asking why there is an outbreak of measles. I am asking why so many people are dying.

This source for the U.S. indicates that the expected mortality rate is one per thousand cases: https://physiciansforinformedconsent.org/measles/dis/

This source indicates that 12,700 cases of measles have been reported, leading to 203 deaths: https://www.who.int/philippines/news/feature-stories/detail/questions-and-answers-on-the-measles-outbreak-in-the-philippines

That's one death per 63 cases. That's 150x higher than expected in the U.S.

submitted by /u/uiuctodd
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How do woodpeckers not get concussions from hitting their heads against trees so hard?

Posted: 30 Apr 2019 10:03 PM PDT

What attribute determines sex?

Posted: 30 Apr 2019 10:03 AM PDT

In humans, males are the heterogametic sex (XY) and females are the homogametic sex (XX). But in the the ZW-sex determination system this inverse (ZZ is male and ZW is female). Other sex-determination systems have even different ways of determining sex (XO, ZO system).

In humans, females are the sex that get pregnant. However, in some fish males are the ones that get pregnant.

In humans, females carry the most care for their child. However, in some species paternal care is more common.

Therefore, what attribute makes males males, and females females? If it isn't anything of these, what is it?

Edit: I thought I had explained myself pretty well, but seeing the answered I guess my question wasn't clear enough. So here's it formulated differently.

This question isn't about humans, it's about classifying different organisms. Obviously there's going to be abornormalities within species that cause differences in sex-outcome, but that shouldn't be included within the scope of this question.

Just imagine we lost all data on all species in the world. And we go back to redetermining the sex of all known species. Why would we call the male of the Hippocampus genus (seahorses) males, because the males get pregnant. What attribute made us decide they were the males.

Then we look at Varanus komodoensis (Komodo dragons), and want to know which ones are males. We look at their karyotype; the males have the ZZ chromosome pair. What attribute made us decide these were the males?

submitted by /u/PaperStreetss
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Is it possible to split a helium nucleus (or an alpha particle) in half?

Posted: 30 Apr 2019 09:20 AM PDT

How high do mountains have to be to affect precipitation?

Posted: 30 Apr 2019 02:45 PM PDT

This one has been bothering me pretty much as long as I've known: Obviously, mountains cause rain shadows by blocking rain, so there's a dry area right next to the ocean. However, where's the limit? For example, is like half a kilometer high enough?

submitted by /u/BringBackByzantium
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Why do some wines get better with age, and some wines go bad?

Posted: 30 Apr 2019 10:43 AM PDT

Why/how does soap clean are skin when we take a shower/wash our hands?

Posted: 30 Apr 2019 04:13 PM PDT

If, as suspected, the earth was hit by Theia early in its creation, why don’t we have a ring of debris around us like Saturn?

Posted: 30 Apr 2019 05:12 AM PDT

Tuesday, April 30, 2019

Why do some birds hop while some of them walk?

Why do some birds hop while some of them walk?


Why do some birds hop while some of them walk?

Posted: 29 Apr 2019 05:05 PM PDT

AskScience AMA Series: I'm an expert on all things springtime and the correspondent on a PBS Nature series about spring, phenology, and citizen science. Ask me anything!

Posted: 30 Apr 2019 04:00 AM PDT

Author and biologist Thor Hanson is a Guggenheim Fellow, a Switzer Environmental Fellow and winner of the John Burroughs Medal. His books include Buzz, The Triumph of Seeds, Feathers and The Impenetrable Forest, as well as the illustrated children's favorite Bartholomew Quill. Hanson's work has been translated into more than 10 languages and earned many accolades, including the Phi Beta Kappa Award in Science and two Pacific Northwest Book Awards. His many media appearances have included "Fresh Air", "Science Friday", "On Point", "To the Best of Our Knowledge", and "Book Lust" with Nancy Pearl.

Thor Hanson is the science correspondent for Nature: American Spring LIVE, a three-part series that showcases the transformations of plants and animals as the season changes. From bears leaving their dens to flowering trees to birds embarking on their epic migrations, the series highlights these natural springtime wonders while acknowledging the impact climate change is having on once predictable patterns and behaviors. Another goal of the event is to inspire people to go outside and get involved with citizen science, helping to collect data that is so important for climate change and seasonal research.

The second episode, "Migrations", will air tonight on PBS and Facebook at 8/7c (check local listings). To catch up on the first episode ("Birth and Rebirth"), visit http://pbs.org/americanspringlive.

Please join us with Thor at Noon ET (16 UT) and ask him anything!

submitted by /u/AskScienceModerator
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How do spiders know where to build their webs?

Posted: 29 Apr 2019 03:22 PM PDT

Do they have any way of knowing where bugs generally fly? Is the one in my bathroom exceptionally stupid or is it just unlucky?

submitted by /u/angermoth
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What makes someone a light sleeper or a heavy sleeper?

Posted: 29 Apr 2019 05:15 PM PDT

And is it possible for a light sleeper to become a heavy sleeper and vice versa? If so, why?

submitted by /u/O_93_
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Why does having a bigger particle accelerator help reach higher energy collisions? Can't we just spin around in a smaller one for longer?

Posted: 30 Apr 2019 12:59 AM PDT

Do violent video games increase aggression in people?

Posted: 30 Apr 2019 04:54 AM PDT

Is it possible to have 0 resistance?

Posted: 29 Apr 2019 07:50 PM PDT

Surely in the formulas this would break everything like V=IR and seems to break every rule, but what about firing singular electrons across a complete vacuum, surely there's no forces generating any resistance on it yet you're sending a current?

submitted by /u/Jmlolz360
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Why can the first electron orbital only hold 2 electrons?

Posted: 29 Apr 2019 08:41 PM PDT

Why doesn't diarrhea kill us when it used to be so fatal?

Posted: 30 Apr 2019 07:38 AM PDT

When we get diarrhea, we generally don't take medicine for it & we don't die from it. Why was diarrhea so fatal back in the day?

submitted by /u/morkani
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Is it possible for their to be "Dark Systems" I.e. Solar systems with no star at the center but rather massive gas giants?

Posted: 29 Apr 2019 02:50 PM PDT

If so how would we ever detect them and what type of planets would surround it?

submitted by /u/miguelsz2
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How much do crumple zones affect a cars stopping time?

Posted: 29 Apr 2019 11:49 PM PDT

Im doing research for a physics project and i cannot find how long a car without crumple zones takes to stop online, its usually just stated to stop abruptly, does anyone actually know how long on average a car without crumple zones takes to stop??

submitted by /u/Udiree
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Do new elements form at the center of a nuclear bomb explosion?

Posted: 30 Apr 2019 01:18 AM PDT

Obviously I'm not well versed in this subject but based on what I've heard, the center of the explosion is as hot as the sun for a very short time. Is that enought to form new and exotic metals or elements? If it does will be in meaningful quantities?

Thanks!

submitted by /u/felinidguardsman
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Why can we vaccinate against some diseases (measles, chickenpox, hepatitis B) but cannot vaccinate against others (HIV, gonorrhea, Ebola)?

Posted: 29 Apr 2019 06:30 PM PDT

What are the atmospheric levels of ethanol from wild sources?

Posted: 30 Apr 2019 01:36 AM PDT

Sorry if the word "wild" seems vague or incorrect, I couldn't think of a better word, but I refer to any source that isn't controlled by humans for human benefit, ie decomposition out in the natural environment. I can't find a clear answer with Google possibly due to not using the right words, but since matter is decomposing all the time, there will be ethanol created by yeasts etc around the world. What if anything is there in the way of a global "average" for the composition of air being ethanol?

submitted by /u/jghunter
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Is their an actual cause/effect relationship between smoking and lung cancer, or is it just correlation?

Posted: 29 Apr 2019 07:30 PM PDT

I've noticed lots that we don't actually know what causes cell mutation, its more or less just a link. e.g. if you smoke you have higher chances of getting cancer. Does this mean they don't actually know if smoking itself causes cancer but some aspect of smoking. So it could be the taste of nicotine affects cells leading to cancer? Just not sure..

submitted by /u/wackojacko666
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How do relativistic jets escape the singularity of black holes when nothing else can?

Posted: 30 Apr 2019 04:51 AM PDT

Black hole gobbles up star and an accretion disk forms. Makes sense. But how does the matter fall into the black hole then get blasted back out? Maybe it never falls past the singularity? Big space nerd but this has eluded me.

submitted by /u/SometimesHelpful123
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Based on the available statistics and every other thing being equal, is it safer to give birth naturally or by Caesarian sectioning?

Posted: 30 Apr 2019 04:45 AM PDT

How far do slugs travel?

Posted: 29 Apr 2019 07:59 PM PDT

Like if you pick up a slug and put it down somewhere else, how far do you have to move it so it won't come back? What's the typical range for a slug?

submitted by /u/GonzoAbsurdist
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Why do excited electrons fall to intermediate orbitals before falling to ground state?

Posted: 29 Apr 2019 01:11 PM PDT

When an electron in an atom is excited it jumps up in energy levels, and then falls back down to a lower energy level and emits a photon. For the Balmer series, the visible emission spectrum of hydrogen, the wavelengths of light are produced by electrons falling to the second energy level. What causes it to stop there, if its just going to then fall to ground state immediately anyway

submitted by /u/jgraham1
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Why, quantum mechanically, is chemical stability dictated by the filling of orbitals?

Posted: 29 Apr 2019 03:29 PM PDT

Elemental fluorine is highly reactive, while Argon is not. Antiaromatic compounds are highly reactive, while aromatics are not.

The chemist's explanation is along the lines of "Argon has a closed shell with all orbitals full, while fluorine does not, and aromatic compounds have their lowest pi-orbitals full, while antiaromatic compounds do not.

Why does this make sense from the perspective of first-principles quantum mechanics?

submitted by /u/throwaway159357n
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Why is it when you crush something plastic (like a water bottle), you can't get it back to its original form?

Posted: 29 Apr 2019 09:51 PM PDT

What determines a child’s temperament? Can the temperament of the parents predict what their future child might be not including external environmental and social upbringing?

Posted: 30 Apr 2019 01:20 AM PDT