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Saturday, October 6, 2018

When is a cave a cave?

When is a cave a cave?


When is a cave a cave?

Posted: 05 Oct 2018 03:19 PM PDT

It's obvious most of the time, everybody knows what a cave is. You walk into a hole in the rock and wow, you're in a cave. But when is a hole in the ground not only a hole but considered a cave by science?

Bonus: Are there fast growing caves that form in a for humans observable timeframe or is it always some Million years of water carving through stone? What about caves formed by earthquakes?

submitted by /u/md63157
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The Gympie Gympie plant (link in comment) can cause pain that lasts years. How does it do this, wouldn't toxins be flushed from your system by then ?

Posted: 06 Oct 2018 03:17 AM PDT

Gympie Gympie stings last an awful long time, with reports saying even after years you can still experience pain. How does this work ?

I was tempted to put this in ELI5, but I'm good with the scientific explanation as it gives me something to deep-dive into Wikipedia to kill a few hours.

submitted by /u/Nandy-bear
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Why do elderly people smell different?

Posted: 06 Oct 2018 02:08 AM PDT

I have many times questioned myself why elderly people have an different odor than young people. Is there an biological explanation on this please?

submitted by /u/Scientia33
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Who owns the moon and other space-related things?

Posted: 06 Oct 2018 04:11 AM PDT

What stops a country to set up a moon base or mine on asteroid for precious metals? Will the colonizing of space be like a "free for all, grab what yours" or are there certain rules?

submitted by /u/AIec18
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In the context of nuclear reactions, what is the difference between prompt criticality and delayed criticality? Why does one result in a nuclear explosion while the other does not despite them both being supercritical reactions?

Posted: 06 Oct 2018 03:01 AM PDT

I already understand the process by which nuclear reactors work to a fundamental level with the ideas of moderators and control rods sorted, but what I cannot seem to understand is the difference between prompt and delayed criticality. Like, both are supercritical so both should in theory result in exponential growth of neutron emissions, right? Rephrasing the question, why is there a sudden difference between 1<k<1/(1-beta) and k>1/(1-beta) despite both resulting in exponential growth of neutrons? I looked up the Wikipedia article on this and it did not help. Thank you!

submitted by /u/aberki1234
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When you get a headache from say, constant loud noise, what exactly is hurting if your brain has no pain receptors?

Posted: 05 Oct 2018 08:08 PM PDT

How long after death does all electrical activity in the brain cease?

Posted: 05 Oct 2018 10:02 AM PDT

Do fever-reducing medicines deprive your immune system of the benefits of having a higher body temperature while fighting an infection?

Posted: 05 Oct 2018 01:03 PM PDT

[Psychology] How does Compassion Fatigue apply to fields not typically associated with trauma, such as technical support?

Posted: 05 Oct 2018 04:18 PM PDT

I'm a team lead in large enterprise support, we commonly deal with disaster scenarios every day where companies risk losing their businesses or livelihoods due to data loss. I've observed many symptoms of Compassion Fatigue in my agents and would like to know if there's any official studies or answers on this topic.

submitted by /u/snakejawz
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If one of the conditions for cancer is replenishing telomeres for unbounded growth, then what happens to cancer growths without this trait? Do they stop growing at a certain size, forming a stable sized tumor?

Posted: 05 Oct 2018 12:52 PM PDT

Is Hawking still correct?

Posted: 05 Oct 2018 01:12 PM PDT

In A Brief History of Time, Stephen Hawking wrote,

"Now at first sight all this evidence that the universe looks the same whichever direction we look in might seem to suggest there is something special about our place in the universe. In particular, it might seem that if we observe all other galaxies to be moving away from us, then we must be at the center of the universe. There is, however, an alternate explanation: the universe might look the same in every direction as seen from any other galaxy too. This, as we have seen,was Friedmann's second assumption. We have no scientific evidence for, or against, this assumption [the assumption that the universe has no center]. We believe it on the grounds of modesty. It would be most remarkable if the universe looked the same in every direction around us, but not around other points in the universe!" (A Brief History of Time 44-45).

My question is this. Have we discovered something since the time Hawking wrote this that would justify the belief that the universe has no center?

Let me clarify my request. I'm not asking for explanations of the data that are merely consistent with the idea that there is no center. I'm asking for evidence that has been discovered since the time of his statement that can be best explained (or only explained) by believing that the universe has no center. I already infer from Hawking's statement that

A) explanations of the data that are merely consistent with the idea that there is no center already existed when he wrote his book, and

B) no evidence existed at the time of his writing that could be best explained (or only explained) by believing that the universe has no center.

Thanks.

Edit: In an ideal world, I could have a source that directly addresses Hawking's statement and demonstrates how what he said is no longer the case, but I will be grateful for whatever assistance is on offer.

submitted by /u/nomenmeum
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During CPR, how does the heart fill back up with blood after a chest compression?

Posted: 05 Oct 2018 01:00 PM PDT

Are smaller organism’s cells smaller than a larger organism’s cells?

Posted: 05 Oct 2018 11:39 AM PDT

What is the full meaning of omega (density parameter) = 1 concerning our universe?

Posted: 05 Oct 2018 03:11 PM PDT

I have been reading through Mapping the Heavens and the chapter over dark energy has left me with some questions I can't find exact answers to. Forgive my questions if they sound ignorant or are worded inaccurately.

  1. From my understanding, omega is the sum of all matter (dark and normal) plus lambda; the former contributes 0.3 to omega and the latter 0.7. However, these numbers aren't exact and omega may be just over or just under 1. However, it seems like the consensus is that it is exactly 1. Is this still the consensus or is there new data?
  2. Also, if omega is 1, then that means our universe's matter is exactly at the critical density to prevent collapse?
  3. Does the former (#2) mean that our universe will continue to expand but stop at some point or will expansion continue accelerating?
  4. What is the fundamental difference between the Big Chill model and the Big Rip model? If the universe continues to expand, would not the Big Chill happen first, followed later by the Big Rip? I don't understand how the latter wouldn't eventually also happen.
submitted by /u/yungskiddy
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What do you call the small broken up islands that surround northern land masses like Greenland?

Posted: 05 Oct 2018 01:40 PM PDT

What do you call the frayed edges of northern land masses like Greenland? The small, broken up pieces of land that sometimes seperate off the main land mass into tiny islands(They are so small, I'm not sure if Island is the correct term.). If I could figure out a way to post a picture, I would circle what I mean in red...

submitted by /u/MFF_zews
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Why can't our brains/bodies restart after dying?

Posted: 05 Oct 2018 07:03 AM PDT

I understand the brain and body need certain nutrients and elements to function and will die without those. Much like a computer needing power, the brain will die without oxygen (for example). But unlike a computer starting up again after being dead by powering it, why can't a brain or some cells that died because of lack or nutrients start up again if they're given those nutrients after death?

submitted by /u/But_IAmARobot
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If the sun is expanding, does that mean that the habitable zone is also changing ?

Posted: 05 Oct 2018 07:37 AM PDT

At what distance does diving into water go from recreational to lethal?

Posted: 05 Oct 2018 11:38 AM PDT

During a harmonic alignment of the planets is the barycenter of our solar system ever outside the sphere of the sun?

Posted: 05 Oct 2018 10:12 AM PDT

Friday, October 5, 2018

Why do some wind turbines have textured edges ?(image in text below)

Why do some wind turbines have textured edges ?(image in text below)


Why do some wind turbines have textured edges ?(image in text below)

Posted: 04 Oct 2018 09:56 PM PDT

I noticed these raised edges on the blade of a wind turbine in this video from Jeff Bezos's Instagram. What are they for?

submitted by /u/CountryOfTheBlind
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Are there any planetary orbital features that we know to be theoretically possible, but have never found an example of in any exoplanet?

Posted: 04 Oct 2018 09:18 PM PDT

What are some orbital phenomena that our models of astrophysics predict as being possible, but we simply haven't found an example of any known planet in the universe having yet?

I'm referring specifically to things orbiting a planet in the vein of rings, moons, interactions between planets, etc., but interesting orbits of planets themselves are fair game too.

submitted by /u/Umutuku
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How where Jurassic Herbivores (like the Stegosaurus) able to physically sustain themselves with only leaves which are so low in Calorie?

Posted: 04 Oct 2018 04:42 PM PDT

I know they where basically eating for the entirety of the day, but I still don't understand how such a big animal could sustain itself with only plants when even a koala eats all day just to sustain.

submitted by /u/befriends1234
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The closest solar system to our own is 4.5 lightyears away, which two solar systems have the closest proximity to each other?

Posted: 04 Oct 2018 08:53 PM PDT

What would atmospheric matter-antimatter explosion look like?

Posted: 05 Oct 2018 03:01 AM PDT

I'm just curious how would a massive matter-antimatter annihilation event (say, 1000 kg of each) look like in the Earth's atmosphere? Would it be similar to thermonuclear explosion? Would there be a massive outburst of high energetic photons or something like that? How much radiation hazard there would be? Would we see a mushroom cloud?

submitted by /u/Astromaniac101
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Why are insects attracted to light sources at night? I.e moths to lamps

Posted: 04 Oct 2018 04:49 PM PDT

Does the oxygen abundance around a plant increase in a closed environment?

Posted: 05 Oct 2018 07:25 AM PDT

Hi, I'm aware that this topic is probably far easier than what is normally discussed in this group but a helping hand would be very much appreciated.

So I'm writing a lab on the effect of varying light intensity on photosynthesis rate. And i'm controlling the light intensity by the distance to the lamp, and photosynthesis rate by measuring the o2 abundance using a vernier. And I put a specific plant inside of a ziploc bag, but after each trial (I did 5 trial each for 5 increments), the oxygen abundance in the bag remains the same if not decreased. I have no idea how to explain this in conclusion/evaluation section. Any explanations on why this could be? I hypothesized that it should increase with closer distance to the light source as the plant will have more available light energy. In the ziploc bag, I do see condensation.

submitted by /u/Paintosaint
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How does optical activity work at the atomic scale?

Posted: 04 Oct 2018 07:06 PM PDT

I am trying to get a good grasp on the use of circular dichroism spectroscopy in biology. So far everything makes sense, but I don't quite understand what exactly causes chiral molecules to exhibit optical activity, and I feel like that is important for a complete understanding.

I read a page that says chiral molecules rotate linearly polarized light when the light interacts with the molecule's electron cloud. But what /exactly/ is happening? What about this interaction causes the rotation of the plane of the electric field's oscillation?

And why doesn't the orientation of the chiral molecule matter? Our hands are chiral, but the shadow of my hand if my palm is facing me looks different than if my palm is facing away. Wouldn't the random orientation of the molecules in solution affect the interaction with light?

Sorry if these questions are confusing, I can reword if necessary. I am not a physicist [but I wish I was :'( ]

submitted by /u/International_Jello
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People talk about "inflammation" in the body often, what exactly is happening in this situation?

Posted: 04 Oct 2018 06:07 PM PDT

When an atom is split is the energy released coming from the gluons?

Posted: 05 Oct 2018 05:21 AM PDT

Gluons seem really interesting, I've learned that they provide 99% of the atoms mass but somehow Higgs get a lot of credit for their 1%. It just got me thinking about gluons, after googling the subject it all seems pretty vague.

submitted by /u/skreed
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When a whale or shark breaches the surface into the air, does everything appear blurry or clear to the creature?

Posted: 04 Oct 2018 10:49 AM PDT

What’s the cellular cause of glaucoma?

Posted: 04 Oct 2018 03:58 PM PDT

I've been researching glaucoma for school, I can't seem to find the specific causes for it. I know that close angle is caused by the iris blocking the drainage angle. But open angle is always referenced as a failure to drain due to blockage, I think it's because calcium builds up in the drainage, I don't have precise proof but is it because of calcium build up in the drainage angles. The question I need answered is what malfunctions on the cellular level but any information is helpful?

submitted by /u/dragonz135
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Are mammals the only type of animals that can get fat?

Posted: 04 Oct 2018 02:47 PM PDT

I've heard of fat people, dogs and cats but I've never heard of a fat lizard, bird or insect.

submitted by /u/themelroser
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Has there ever been more living beings in the planet than right now or is this the period that’s seen the most life?

Posted: 04 Oct 2018 12:16 PM PDT

Is it even possible to answer this question?

submitted by /u/Ebvardh-Boss
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Has the amount of radiation earth puts out into space risen due to humans?

Posted: 04 Oct 2018 03:52 PM PDT

Do our nuclear devices, electronics, atomic blasts, etc. effected the total radiation that earth gives off over the course of the past 300 years?

submitted by /u/sandiegopic
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Do different types of cells have chromosomes with different initial telomere length?

Posted: 04 Oct 2018 09:29 AM PDT

Otherwise what allows for the difference in lifespan between a neuron and an epithilal cell for example?

submitted by /u/GleepGloopGlop
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Is a virus (mono, for instance) contagious in its incubation period?

Posted: 04 Oct 2018 06:00 PM PDT

Does nuclear radiation have a "signature"?

Posted: 04 Oct 2018 09:41 AM PDT

Like if I took something from an area that was highly irradiated like Chernobyl of Fukushima could you examine in and just by measuring the radiation could you tell where it was from?

submitted by /u/GorillaGravy
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Thursday, October 4, 2018

I have recently heard that astronomers have found an "exomoon". I am quite scientifically illiterate so what exactly is an exomoon and how could it affect us on Earth?

I have recently heard that astronomers have found an "exomoon". I am quite scientifically illiterate so what exactly is an exomoon and how could it affect us on Earth?


I have recently heard that astronomers have found an "exomoon". I am quite scientifically illiterate so what exactly is an exomoon and how could it affect us on Earth?

Posted: 04 Oct 2018 04:09 AM PDT

Do Rockets harm the environment in terms of exhaust fumes?

Posted: 04 Oct 2018 04:07 AM PDT

I ask me this question when in saw Elon Musks demo of the BFR carrying passengers or cargo from Earth-to-Earth anywhere on the Earth within 90 minutes.

submitted by /u/Knastbruder33
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What are the long-term effects of repeated soft tissue bruising and damage?

Posted: 03 Oct 2018 11:04 PM PDT

Athletes often suffer injuries to parts of the body from repeated stress over time. What about soft tissue? What happens if a spot on your body is repeatedly bruised and subjected to damage over and over again over a period of years?

submitted by /u/MisterJose
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Is it possible to travel faster than the apeed of sound through a liquid?

Posted: 04 Oct 2018 07:29 AM PDT

Has it been done before? What would that look like? Would there be anything cool to see like when planes pass through the sound barrier and that vapor wall builds up? Thanks.

submitted by /u/swill128
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Does the temperature of a room change the rate of which a candle burns?

Posted: 04 Oct 2018 06:28 AM PDT

Why are common allergies like bee stings and peanuts... common?

Posted: 04 Oct 2018 03:40 AM PDT

I'm just curious if there's something underlying that makes us more susceptible to very specific allergies

submitted by /u/Sintarical1
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How do nuclear reactors/atomic bombs prevent a fission reaction before it is wanted?

Posted: 03 Oct 2018 06:30 PM PDT

I know how fission reactions work (to a certain extent atleast), but how are the neutrons contained and prevented from starting a reaction at any random point in time? Shouldn't a reaction start the second any neutron at high enough energy hits the nucleus of another atom, and therefore be completely unpredictable?

submitted by /u/ElectroSfere
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On MRI background checks, why are tattoos listed along with other metal objects?

Posted: 03 Oct 2018 11:48 PM PDT

How have ancient cave and wall paintings stayed preserved over time with some 40,000+years old?

Posted: 04 Oct 2018 12:10 AM PDT

How do gas giants like Jupiter "die" in star systems that don't go supernova?

Posted: 03 Oct 2018 11:29 AM PDT

Does getting the flu shot in the US help protect you from flu virus in other countries?

Posted: 04 Oct 2018 03:57 AM PDT

Hi everyone, I am an American living in Germany. I will be traveling to the US in a few weeks and wondering if it makes sense to get my flu shot there. Will this protect me or are there different flu strains in different countries? From my knowledge, getting the flu shot is not common practice in Germany like it is in the US. Typically it's only for high risk patients like the elderly or pregnant women.

submitted by /u/letsfiesta
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Does a human body emit neutrinos?

Posted: 03 Oct 2018 10:08 AM PDT

I read that our body emits a small amount of radiation, notably through the decay of Potassium 40 and Carbon 14. But this type of decay results in the emission of positrons, if I understand correctly.

Is there another type of decay happening in our body that emits neutrinos?

I wonder if our body sends small pieces of information through the universe, broadcasting our existence light-years away...

submitted by /u/1-Sisyphe
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Change in enthalpy for transition of carbon in the diamond form to carbon in the graphite form is apparently a negative number (-453.5 cal). According to this, graphite is more stable than diamond, how’s that possible? Isn’t diamond supposed to be stronger and more stable than any other material?

Posted: 03 Oct 2018 10:54 PM PDT

Can someone give a layman's explanation of how to obtain a probability density model for atoms using the Schrödinger wave function?

Posted: 03 Oct 2018 01:38 PM PDT

I realize this might be a tough ask, but I just came across this photo the other day and thought it was pretty inspiring. I was wondering if the shapes of all the atoms have been mapped in a way like this. Is this photo an accurate representation of the Schrödinger equation of hydrogen orbitals?

submitted by /u/BlazesAndAmuzed
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Is there any universal unit for time that isn't based from our stellar perspective? I know caesium-133 and strontium are used to get extremely accurate measurements but it's only in reference to our solar system.

Posted: 03 Oct 2018 05:49 PM PDT

Is it possible to design acoustic "distributed-element filters" using a similar approach to that employed in the RF and Microwave electronic field?

Posted: 03 Oct 2018 03:43 PM PDT

When shooting at / from an helicopter, does the shooter needs to aim higher to compensate for the force from the main rotor ?

Posted: 03 Oct 2018 12:31 PM PDT

If a pregnant woman got mono, once she recovered and developed immunity, would the child passively receive immunity as well?

Posted: 03 Oct 2018 08:16 PM PDT

How come the heat from the sun hits the earth roughly the same time as the light from the sun?

Posted: 03 Oct 2018 04:07 PM PDT

The sunlight takes 8 minutes and 20 seconds to get hear. Surely heat will take a lot longer?

submitted by /u/Arbane
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Why is blue light scattered and not absorbed in the sky?

Posted: 03 Oct 2018 05:03 PM PDT

The resonant frequency of N2 and O2 is similar to blue light's frequency, so wouldn't the molecules just absorb the light instead of scattering it?

submitted by /u/TechSupport15
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Can Cobalt-60 be used for PET scans?

Posted: 03 Oct 2018 09:33 PM PDT

How are space probes like Cassini protected from colliding with asteroids and space scrap?

Posted: 03 Oct 2018 09:51 AM PDT