Pages

Monday, December 3, 2018

What actually determines the half-time of a radioactive isotope?

What actually determines the half-time of a radioactive isotope?


What actually determines the half-time of a radioactive isotope?

Posted: 03 Dec 2018 03:45 AM PST

Do we actually know what determines the half-time of a radioactive isotope? I tried to ask my natural science teacher this question, but he could not answer it. Why is it that the half-time of for an example Radium-226 is 1600 years, while the half-time for Uranium-238 is 4.5 billion years? Do we actually know the factors that makes the half-time of a specific isotope? Or is this just a "known unknown" in natural science?

submitted by /u/skadabombom
[link] [comments]

What was the Amazon like when the Sahara was still green?

Posted: 02 Dec 2018 09:12 AM PST

The sandstorms from the Sahara are cited as a contributing factor to how big the Amazon is because of all the mineral nutrients that are carried in the sand to Amazon soil (and North American soil as well). Well what was the region like a few thousand years ago when those sandstorms weren't happening?

Was it it's own dessert? Or did the Amazon river support a river plain like the Mississippi River basin in the US and Canada?

submitted by /u/Rancerle
[link] [comments]

Can bugs feel pain?

Posted: 02 Dec 2018 10:43 AM PST

I once read in one of those CWF Wild magazines years ago that bugs cant feel pain because their nervous system is too small. Does anyone know if this is true, and if so what causes it?

submitted by /u/StormShadow921
[link] [comments]

how does Van der Waals force play a part in adsorption of gas on solid surface?

Posted: 03 Dec 2018 05:28 AM PST

How do complex mutations happen through evolution?

Posted: 02 Dec 2018 11:15 AM PST

How do extremely complex organs come to exist through mutations? I don't think that a single mutation could cause something as complex as eyes to exist but it's also hard to believe that a small mutation like the beginning of eyes would be valuable enough for natural selection to create a large enough population of it for it to mutate again.

submitted by /u/AtlasCommunity
[link] [comments]

How does NH4+ interfere with Oxidative Phosphorylation?

Posted: 02 Dec 2018 09:09 PM PST

Optics question: What are the lines of light in clear water called?

Posted: 02 Dec 2018 12:58 PM PST

For instance, the lines of light that are reflected in this photograph.

[Imgur](https://i.imgur.com/KGeDZR5.jpg)

submitted by /u/Psidius
[link] [comments]

Why do people get morning breath?

Posted: 02 Dec 2018 05:23 PM PST

Also, why don't we get it throughout the day?

submitted by /u/Bren0829
[link] [comments]

What would happen gravitationally if Earth where surrounded by a hollow sphere?

Posted: 02 Dec 2018 02:42 PM PST

Based on Newtonian Gravity/Newton's Shell Theorem the gravity caused by they sphere would be zero inside, so would Earth just drift within the sphere?

submitted by /u/cilantno
[link] [comments]

What does "thinness" or "thickness" of air imply and how does it happen and change?

Posted: 02 Dec 2018 10:25 AM PST

Does the southern hemisphere see different stars to the northern hemisphere?

Posted: 02 Dec 2018 01:19 PM PST

Why is quantum entanglement so important to quantum computing?

Posted: 02 Dec 2018 10:05 AM PST

I understand that superposition allows for multiple operations to go on at once, and I understand quantum entanglement. I keep reading that entanglement is involved in quantum computing but I cant find a definitive answer as to how it actually helps.

Thanks in advance for your help :)

submitted by /u/prongs392
[link] [comments]

What makes one particular material good at dampening sound versus another material?

Posted: 02 Dec 2018 10:13 AM PST

I'm sure it's more than a function of material density. Is there a metric for a materials ability to convert acoustic waves to phonons which permit photonic emission?

submitted by /u/DrLetric
[link] [comments]

How will the redefinition of a Kilogram affect the Atomic Masses/Moles of the periodic table?

Posted: 02 Dec 2018 10:01 AM PST

Why do obstructions occur more frequently in the coronary arteries than other vessels throughout the body?

Posted: 02 Dec 2018 09:41 AM PST

It is my understanding that a heart attack is caused by plaque build up in the coronary arteries. Correct? Why do we never hear about obstructions in other vessels? What is it about the vessels of the heart that make them more prone to obstruction?

submitted by /u/IsntItNeat
[link] [comments]

How do heart rate measurement apps manage to do their job by just using your phone's camera and flash?

Posted: 02 Dec 2018 05:35 AM PST

Why do increased insulin levels aid in the absorption of creatine monohydrate?

Posted: 02 Dec 2018 12:29 PM PST

When you're ill why does the body keep trying to throw up even if our stomach is empty? Can it not tell?

Posted: 02 Dec 2018 03:39 AM PST

Very recently I was ill and being sick every couple hours. But after a couple times I was just dry heaving as I had nothing left in my stomach. I'm wondering why my body couldn't tell my stomach was empty and kept trying in vain to throw something up.

submitted by /u/Im_a_human_man
[link] [comments]

If a woman is born with all her eggs at birth, how can her age at conception influence Down’s syndrome?

Posted: 02 Dec 2018 08:16 AM PST

Down's syndrome is trisomy, a chromosomal separation error in Meiosis. Because it is more common in older mothers I imagine the trisomy comes in the egg. But if eggs are ready at birth, how do the eggs with trisomy come later in life? Are the egg cells "set aside and ready" at birth but actually experience Meiosis close to ovulation?

submitted by /u/diogenes_shadow
[link] [comments]

How does the brain store/retrieve language?

Posted: 02 Dec 2018 08:32 AM PST

Sunday, December 2, 2018

If microevolution is evident given the way microbes evolve in response to antiobiotics+vaccines, wouldn't microevolution also be present in our own microbiome, serving as observable evidence of evolution in humans+other animals?

If microevolution is evident given the way microbes evolve in response to antiobiotics+vaccines, wouldn't microevolution also be present in our own microbiome, serving as observable evidence of evolution in humans+other animals?


If microevolution is evident given the way microbes evolve in response to antiobiotics+vaccines, wouldn't microevolution also be present in our own microbiome, serving as observable evidence of evolution in humans+other animals?

Posted: 02 Dec 2018 03:34 AM PST

TL;DR - listening to microbiology podcast episode, microbiologist+podcaster mentioned [bad] microbes being originally believed to be supernatural/demons [with no knowledge of good microbes, or microbes at all], I recalled that microevolution is observable, people deny macroevolution for lack of contemporary observability, supernatural belief is generally pitted against macro scale evolution (stating that we "can't observe" it), our body has a microbiome which contributes to certain fundamental biological aspects/functions,etc., this sounds to me like potential observable evidence of evolution in humans+other animals.

I was just thinking about this listening to the microbiology episode of the Ologies podcast and it got me thinking about our understanding of evolution starting at the micro scale in relation to supernatural beliefs. Bare with me.

Specifically, I was thinking about how she mentioned that the English word "bug" (in reference to bacteria/microbial bugs) comes from a Welsh word for ghost or evil spirit. It reminded me of a few weeks ago when I was listening to Joe Rogan speaking to someone (I think it was Elon Musk) and they were mentioning how we have the problem of making new antibiotics and vaccines every year because microbial bugs continue to adapt to the treatments and evolve into newer, stronger bugs. I.e., some of them "superbugs".

Edit: the microbiologist she was interviewing also spoke about how changing the gut bacteria in mice (among other animals) made them behave differently. Would that possibly indicate something in relation to humans?

Edit 2: Also was reminded that up to 90% of our serotonin is produced by gut bacteria, so the state of our microbiome obviously plays an integral role in our general state of being and our behavior.

An example I think about all the time, for those who don't know, is saying the phrase "bless you" or "God bless you" after a person sneezes which stems from people once believing that sneezing was our soul getting rid of evil spirits/demons in our body, or another origin stating that a Pope thought people were dying (or something of the likes) when they coughed and sneezed so this short blessing would protect them. And centuries later, even tho we understand allergies and inhaling dust and mucus production and the common cold, etc. is not demons or deadly, most people still say "[God] bless you" after a person sneezes.

And if anyone here happens to have played God of War you might remember when Sindri tells you that Freya discovered "little beasties" (microbes/bacteria) on everything lol, and said they were responsible for human sickness. Just a funny reference to how people once did believe microbes and their effects on us was a supernatural matter.

My point in emphasizing our understanding, or lackthereof, during that part of history is that supernatural beliefs are generally pitted against biological evolution. But the irony is that what once was considered a supernatural phenomenon by those fundamentally against evolution, now seems to serve as clear evidence of evolution.

It seems like people subconsciously think less objectively, or less overall, about the matter or just deny whatever they're told, but somehow many people will still consciously accept what we've learned from the matter.

submitted by /u/fuckingblackmale
[link] [comments]

Is Quantum Mechanics Really Random?

Posted: 01 Dec 2018 09:51 PM PST

Really dumb it down for me, I don't know much about Quantum Mechanics. I have heard that quantum mechanics deals with randomness, and am trying to understand the implications for our understanding of the universe as deterministic.

First of all, what do scientists mean when they say random? Sometimes scientists use words differently than most people do. Do they mean random in the same way throwing a dice is 'random'? Where the event has a cause and the outcome could theoretically be predicted, but since we don't have enough information to predict the outcome we call it random. Or do they mean random in the sense that it could literally be anything and is impossible to predict?

I have heard that scientists can at least determine probabilities (of the location of a particle I think), if you can determine the likelihood of something doesn't that imply that something is influencing the outcome (not random)? Could these seemingly random events simply be something scientists don't understand fully yet? Could there be something causing these events and determining their outcome?

If these events are truly random, how do random events at the quantum level translate into what appears to be a deterministic universe? Science essentially assumes a deterministic universe, that reality has laws that can be understood, and this assumption has held up pretty well.

submitted by /u/archon325
[link] [comments]

Does gamma radiation excite nuclei?

Posted: 02 Dec 2018 05:58 AM PST

Since exicted nuclei emit gamma radiation to get back into their ground state, can they also absorb (certain wavelenghts of) gamma radiation?

Going further than the general question above: Could gamma radition be used to deliberatly excite a nuclei, possibly leading to fission (or induce alpha/beta decay in fitting isotopes) or fusion of several, nuclei already under high pressure/temperature?

Would a (hypothetical) gamma ray laser be useful to create fusion on demand, possibly even a fusion power plant?

(And while I am at it: Is there recent research about those hypothetical gamma lasers? From googling around all I could find articles indicating there's some occasional research going on for the last 60 decades, but nothing too promising).

submitted by /u/TheRealStardragon
[link] [comments]

How do we measure eccentricity in the orbits of stars around galactic centers?

Posted: 02 Dec 2018 07:32 AM PST

One of the things that led people to assume that we need "dark matter" is that the orbits of stars around the galactic center of mass is "too fast" as you move out from the center. How do we differentiate between stars that are in circular orbits that are too fast for the known mass distribution from stars in more eccentric orbits that happen to be in a lower portion of their orbit right now and are moving faster as a result?

submitted by /u/froginthelibrary
[link] [comments]

What is the default state of the muscles that are responsible for closing your eyes?

Posted: 01 Dec 2018 03:29 PM PST

If you were to turn 'off' the muscles that open/close your eyelids, would your eyes stay open or closed? I know that the majority of the time when people die, their eyes stay open, but it is possible to close the eyes and have them remain closed. When we go to sleep, we almost feel like our eyes are wanting to naturally close, but when we're awake, it's very easy to keep them open, so would that mean that we're using our eyelid muscles constantly when we are awake?

Edit: grammar

submitted by /u/Willdrow
[link] [comments]

Are animals able to count and do they have any idea of numbers?

Posted: 01 Dec 2018 04:27 PM PST

If we ever have the opportunity to mine other planets like Mars, will we discover similar gems, crystals and precious metals like we do on Earth?

Posted: 01 Dec 2018 06:47 PM PST

Does classical thermodynamics hold up at relativistic speeds?

Posted: 01 Dec 2018 10:39 AM PST

Hi there, undergrad materials engineer here. I was wondering if classical thermodynamics would hold up for matter traveling at relativistic speeds. The idea behind this question started with a friend and I discussing accretion discs of black holes, and wondering how to model diffusion/mixing processes as one nears the event horizon. Questions like how would the chemical potential for adding a proton to the accretion disk change if the matter of the disk were travelling at .9c and the proton was travelling at v << c verses v =.9c?

submitted by /u/Phalcone42
[link] [comments]

Is the perception of heat linear or nonlinear?

Posted: 01 Dec 2018 10:11 AM PST

I have always felt that when microwaving food, it quickly transitions from lukewarm to way-too-hot.

This makes me wonder, is our perception of heat linear or nonlinear?

For example, if the temperature of my soup goes up by 10%, does my perception of the hotness go up by 10% or some other factor?

The possibility reminds me of how we process hearing, which is more logarithmic.

submitted by /u/eternusvia
[link] [comments]

How do satellites know when they're close to one another?

Posted: 01 Dec 2018 05:17 PM PST

A couple of months ago it was announced that a Russian satallite, the Luch-Olymp had come suspiciously close to a French satellite the Athena-Fidus.

According to many sources the Russian satellite came within 10km of the French one, how was this known? Does each satellite have sensors to see if other satellites are near to it?

submitted by /u/HunTer_286
[link] [comments]

Do reptiles and bugs fart?

Posted: 01 Dec 2018 10:02 AM PST

For context, this was a thought because of the recent news of a spider species that feeds milk to its young. Someone suggested it could be a environmental boon if we had spider milk versus cow milk.

I doubt any of that is feasible but it got me wondering if non-mammals toot?

submitted by /u/dagmx
[link] [comments]

Does Cancer continue spreading in a dead body?

Posted: 01 Dec 2018 01:23 PM PST

Does cancer need a living host in order for it to spread, or can it continue to spread even after the person dies?

submitted by /u/brilliantlyabby
[link] [comments]

What would the day/night cycle be like on a NON-tidally locked moon?

Posted: 01 Dec 2018 05:56 PM PST

It seems to me that at least half the time it would be night time everywhere on the surface as the moon moves behind its planet relative to the sun, but the other half of the time would be a more typical day/night cycle as viewed from the surface. I'm having a hard time confirming this just by Googling and using Wikipedia, as most of the major moons I can think of are tidally locked.

submitted by /u/absolute_future
[link] [comments]

How are the IV curves of solar cells determined?

Posted: 01 Dec 2018 05:46 PM PST

Hi all, I'm having a hard time understanding the IV curve of a solar cell. All the sources that I have consulted are saying that it is literally the IV curve of a regular PN junction shifted downwards. The amount of shift depends on the amount of illumination. However what I'm confused about is whether or not we bias the solar cell. E.g. here is a IV curve of a regular PN diode. The "forward bias" region in the image is due to the experimenter hooking up a voltage supply to the diode and measuring the current as a function of the value of the external voltage supply. The "reverse bias" region in the image is similarly due to reversing the polarity of the external voltage source and measuring the current.

Now, is this how the IV curves for a solar cell is also produced? I.e. do we apply an external voltage source, in addition to an illumination source, to get the IV curve of a solar cell?

A related question is: are solar cells operated under a forward bias? I know that in order for a solar cell to produce power, we must look at the 4th quadrant of its IV curve, since in this case the passive sign convention dictates that power is being generated. Here is the IV curve of a solar cell. While the cell is being illuminated, it shifts downwards, and a part of the illuminated IV curve passes through the 4th quadrant of the graph. So, in order for the solar cell to produce power, it must be operating in the 4th quadrant. However, the voltage in the 4th quadrant is positive. I'm not sure how to interpret this voltage. Is this voltage the voltage that is being supplied to the solar cell externally? I.e. similar to applying an external voltage to a PN diode to record its IV characteristics? So does this mean that the solar cell (e.g. a solar panel that is being used to power up a house) is operated under a forward bias?

Different sources say different things. This source suggests that solar cells are not operated under ANY bias. In this source, different answerers give different responses.

Maybe I'm not understanding the concept of biasing? Maybe biasing means different things when used in the context of PN diodes and BJT transistors vs. a solar cell?

Are solar cells operated under a bias? What does "bias" mean in this case? Does it mean simply connecting an external voltage source to the solar cell? Or does it mean something else?

Thanks for your help guys! :)

submitted by /u/DoctorKokktor
[link] [comments]

If breaking the speed barrier causes a sonic boom, then why isn’t light or space radiation constantly causing booms?

Posted: 01 Dec 2018 01:36 PM PST

Why and how do small fishes (like goldfish) overfeed themselves to their death?

Posted: 01 Dec 2018 11:24 AM PST

What causes mosquito and other bug bites to swell up?

Posted: 01 Dec 2018 04:27 PM PST

First post here. I'm just curious about what exactly causes the swelling and itchiness when someone is bitten by a spider or insect, and couldn't find an explicit answer online.

submitted by /u/ThoseFreeFries
[link] [comments]

How do you control the torque curve of an electric motor?

Posted: 01 Dec 2018 09:28 AM PST

Edit: To clarify, I'm curious if torque/power curves for electric motors can be tuned similar to torque/power curves for internal combustion engines and either how or why not. Thanks!

submitted by /u/T2QTIW31hmtGbNsq
[link] [comments]

What happens at the cellular level when leaves turn from green to other colors in autumn?

Posted: 01 Dec 2018 09:18 AM PST

Leaves turning is essentially the death of the leaf right? So if chloroplasts reflect green light, do these dying chloroplasts reflect the yellow, red, orange, brown colors we see?

submitted by /u/bencargo30102
[link] [comments]

Saturday, December 1, 2018

What is "foaming at the mouth" and what exactly causes it?

What is "foaming at the mouth" and what exactly causes it?


What is "foaming at the mouth" and what exactly causes it?

Posted: 01 Dec 2018 05:52 AM PST

When someone foams at the mouth due to rabies or a seizure or whatever else causes it, what is the "foam"? Is it an excess of saliva? I'm aware it is exaggerated in t.v and film.

submitted by /u/GigaHunter93
[link] [comments]

Does the force of ejaculation influence the probability of impregnation, or is this only determined by the swimming speed of individual sperm cells?

Posted: 30 Nov 2018 07:50 AM PST

Seeing as the speed of sound is the speed at which sound waves translate through the air (roughly) Does that mean the speed of sound is slower at, say 60,000’ than Sea Level?

Posted: 01 Dec 2018 05:50 AM PST

Why is it that when you rub your eyes you start seeing weird colours and patterns?

Posted: 01 Dec 2018 03:16 AM PST

I've heard about efforts to eliminate mosquitoes by genetically modifying them to be sterile. How would the gene spread if the individuals with this gene couldn't have any offspring?

Posted: 30 Nov 2018 11:33 PM PST

What causes phosphorescence in the ocean?

Posted: 01 Dec 2018 06:58 AM PST

And is there a correlation between red tide and phosphorescence

submitted by /u/hd_40307_g
[link] [comments]

Since objects get denser as they get colder, would you be able to get ice that was cold enough to sink in water?

Posted: 01 Dec 2018 03:04 AM PST

Between cycloalkyl substituent and double bond in an alkene which one has higher priority ?

Posted: 01 Dec 2018 06:05 AM PST

Why can you only get black widow antivenom once in your lifetime?

Posted: 30 Nov 2018 09:10 PM PST

If an animal within a group (chimps, wolves, etc.) is infertile, are they ostracized by others of their group, or is it not 'noticed' at all?

Posted: 30 Nov 2018 08:11 AM PST

As the title says! I've been reading up on evolution, and for some reason this question came to my mind. The book (The Human Body) puts a lot of emphasis on how natural selection played a role in making our bodies are they are, obviously through breeding 'advantageous' characteristics, and it made me wonder what happens to animals in the wild who are infertile.

I had a quick look on the internet, of course, but really couldn't find much in the way of evidence to answer my question.

So:

Is infertility 'noticed' somehow by the whole community (e.g. horde of chimps or pack of wolves?). After all, these animals can smell/sense/see when a female is in her most fertile period, so is it possible they can also sense when one of their females/males is infertile?

What happens if such a thing is 'found out'? Will the animals be ostracized for not being able to breed?

Does it affect their individual behaviour in any way, e.g. do female animals feel more motherly or less towards offspring from different females?

PS: Yes, I am aware all of what I have said it really really generalized and a lot of species will differ from each other in this regard, but I'm only looking for a simple, basic overview. Also, please don't nitpick about what evolution/natural selection really is, but focus on the question at hand. I have not explained either of the concepts very well, most likely. I am not a biologist. I'm simply interested and would like to know the answer to my question, not fight about what evolution and natural selection are in detail.

submitted by /u/Calathe
[link] [comments]

What methods do scientists use to reconstruct dinosaur postures from discovered fossils?

Posted: 30 Nov 2018 11:19 PM PST

I had a thought today, specifically about Brachiosaurus and its portrayal of constantly holding its head extremely high up. This posture doesn't seem to make sense to me. Based on theories about bird ancestry tying in to dinosaurs, would it make more sense to reconstruct the dinosaur keeping its neck in a tight S-shape like modern birds?

The green heron is a great example of what i'm talking about, with its resting neck posture giving it a relatively short and neck-less appearance due to feather coverage, but its neck can extend to many times its resting length.

How strongly does evidence point towards the current depiction? Could it be because the neck-extending action of birds is more of an attack mechanism for capturing small prey, and the Brachiosaurus is thought to have eaten from tall trees?

Though my idea was specific to one species, I'd still like to know what goes into the reconstruction of dinosaur posture in general. With mostly bones to go on, how does the paleontological community decide how a dinosaur would stand or how it would move?

submitted by /u/integral-e-to-the-x
[link] [comments]

Does an unbound electron have transnational energy levels as it moves through space?

Posted: 30 Nov 2018 04:43 PM PST

Genetically speaking, why is inbreeding bad? What happens with the genes, why do mutations occur?

Posted: 01 Dec 2018 04:12 AM PST

What happens to the elastic potential energy stored in a deformed body when the body breaks or enters plastic deformation?

Posted: 30 Nov 2018 08:35 PM PST

Can Radio Telescopes pick up strong signals outside of where they aim?

Posted: 01 Dec 2018 02:52 AM PST

The purpose of my question is for a science fantasy story I've been making. In it, the sun gives off a distinct signal that suggests life—Not life on the sun, but in it. Was the sun to send a radio message to Earth, would radio telescopes be able to pick it up if they weren't aimed at the sun? How far off could these telescopes be aimed before they'd pick it up?

submitted by /u/Boomsta22
[link] [comments]

Has the Poincaré Recurrence Theorem been observed for in a real system? Can we build a sufficiently small system where this can be achieved?

Posted: 01 Dec 2018 02:48 AM PST

What happens to our stomach that makes us vomit when we eat too much food?

Posted: 01 Dec 2018 01:10 AM PST

Will the two Mars rovers ever meet? And if so would they be programmed to recognize each other?

Posted: 30 Nov 2018 05:28 PM PST

Why does your risk of cancer increase as you age? Don't your cells divide less as you get older?

Posted: 30 Nov 2018 10:58 AM PST

Is there a unit for pain?

Posted: 01 Dec 2018 12:15 AM PST

How do Bacteriophages know their targets and how to get to them?

Posted: 30 Nov 2018 11:53 PM PST

What is the functional difference between taking a blood sample and taking a urine analysis test?

Posted: 30 Nov 2018 04:12 PM PST

What information can you get from both/one vs. The other

submitted by /u/Procrusties
[link] [comments]

What is the difference between Creutzfeldt-Jakob disease(CJD) and variant Creutzfeldt-Jakob disease(vCJD)?

Posted: 30 Nov 2018 11:28 PM PST

Is the difference just the origin of the disease? Don't really get it. Thanks!

submitted by /u/GGTheBrigadier
[link] [comments]