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Friday, September 27, 2019

AskScience AMA Series: I'm Dr. John Troyer, Director of the Centre for Death and Society at the University of Bath and I'm here to talk about death, dying, dead bodies, grief & bereavement, and the future of human mortality. Ask Me Anything!

AskScience AMA Series: I'm Dr. John Troyer, Director of the Centre for Death and Society at the University of Bath and I'm here to talk about death, dying, dead bodies, grief & bereavement, and the future of human mortality. Ask Me Anything!

AskScience AMA Series: I'm Dr. John Troyer, Director of the Centre for Death and Society at the University of Bath and I'm here to talk about death, dying, dead bodies, grief & bereavement, and the future of human mortality. Ask Me Anything!

Posted: 27 Sep 2019 04:00 AM PDT

Hello Reddit, my name is Dr John Troyer and I am the Director of the Centre for Death and Society at the University of Bath. I co-founded the Death Reference Desk website (@DeathRef), the Future Cemetery Project (@FutureCemetery) and I'm a frequent commentator for the BBC on things death and dying. My upcoming book is Technologies of the Human Corpse (published by the MIT Press in 2020). I'll be online from 5-6pm (GMT+1; 12-1pm ET) on Friday 27th September to answer your questions as part of FUTURES - European Researchers' Night 2019.

submitted by /u/AskScienceModerator
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How far can we travel away from Earth?

Posted: 26 Sep 2019 07:03 PM PDT

I'm taking a Cosmology class right now, and I recently watched this kurzgesagt video about our absolute boundary in the universe. So far in class we've mostly just been going over the expansion of the universe, so I tried to justify the assertion in this video to myself: we cannot travel outside of our local group.

The Hubble constant at the current time is 70 kilometers per second per megaparsec. I set up an equation where the change in distance, dx, is equal to the hubble constant times the distance times the change in time, dt. Solving the differential equation, you get that the final distance is equal to about 1.03 times the initial distance over the course of 500 million years. Something about 3 mpc away (the diameter of the local group) would not even increase in distance by a megaparsec. At half the speed of light, you could travel about 77 mpc in this time. This is ~25 times the diameter of the local group.

I know that the Hubble parameter changes in time, but my textbook seemed to suggest that it would not change in any meaningful way over the course of 500 myr. Even if it increased by two orders of magnitude (I tried this by just having it start at two orders of magnitude higher), the distance is still well within travel distance.

Where is Kurzgesagt getting this from, then? I feel like I'm missing something entirely or that I'm wrong about the evolution of the Hubble parameter in time.

submitted by /u/KirsnickBall
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How active a radioisotope source do you need to get clearly visible (to the naked eye) light from a scintillator?

Posted: 27 Sep 2019 02:11 AM PDT

How do individual pixels come together together to form images?

Posted: 26 Sep 2019 08:13 PM PDT

Hoping I chose the right flair.

submitted by /u/KineticDream
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Gamma ray bursts can travel faster than light in a jet medium?

Posted: 26 Sep 2019 12:38 PM PDT

https://www.sciencedaily.com/releases/2019/09/190924152835.htm

That article is way over my head, can someone explain?

submitted by /u/PHealthy
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If someone receives a donated organ, can that organ be donated again when they pass?

Posted: 26 Sep 2019 12:27 PM PDT

How do some Modified Release medication have lower dosage requirements as compared to the instant release medication?

Posted: 27 Sep 2019 02:14 AM PDT

First of all - is there a difference between Extended Release, Substained Release & Modified Release?

Second - the question in the title
For e.g. Metformin, the recommended dosage doesn't change much irrespective of whether you are prescribed the instant release or extended release version. You may be prescribed 500mg Metformin Instant twice a day or 1000mg ER once day which works to the same 1000 mg a day.

But this is not true for all medication.

For e.g. Gliclazide Modified Release is prescribed at a much lower dose than the instant release one

https://www.ncbi.nlm.nih.gov/pubmed/12076188

In a randomised, double-blind, multicentre study, gliclazide MR 30 to 120 mg once daily showed similar efficacy to gliclazide immediate release (IR) 80 to 320 mg/day (in divided doses for doses >80 mg)

How come lesser dosage of the modified release gives same efficacy as the instant release?

Also seen this with other meds like Indapamide, Zolpidem etc.

submitted by /u/TheGlugGlug
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Do other animals understand and comprehend photos/videos?

Posted: 26 Sep 2019 12:50 PM PDT

Does the volume of water on earth fluctuate from day to day?

Posted: 26 Sep 2019 12:30 PM PDT

Can you make supersonic incompressible flow?

Posted: 26 Sep 2019 11:51 AM PDT

It seems like just increasing pressure in a reservoir and having a small outlet would be sufficient to cause supersonic incompressible flow. (Say the flow is water). This would work through the Bernoulli equation and area*velocity=constant which hold for incompressible flow.
However, recently I came across the equation: (M2-1)dV/V=dA/A. I think this equation should hold for both incompressible and compressible flow. It implies that there must be a throat to compress the flow to Mach 1. Then, the throat must diverge to provide supersonic flow.
Where this doesn't make sense to me is that area*velocity=constant must also hold. So, if the throat diverges, the velocity must decrease since density stays constant.
The only possible explanation I could come up with is that the density actually does change because empty space is created while velocity and area increase?

submitted by /u/PlanesAndRockets
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Why are some galaxies names things like "Andromeda" and "Sombrero" while others are referred to as "NGC 3923" and "M82"?

Posted: 26 Sep 2019 08:40 AM PDT

Is there an inherent physical reason why Earth's seasons occur over the same period of time as its year?

Posted: 26 Sep 2019 08:41 AM PDT

Do male bees know they will die after mating?

Posted: 26 Sep 2019 04:14 AM PDT

Why do we need spinors?

Posted: 26 Sep 2019 05:19 AM PDT

I understand that there is some important connection between spin and the groups SU(2) and SO(3). It's often pointed out that SU(2) double covers SO(3), and that the Pauli matrices form a basis for the Lie algebra su(2) (up to a factor of i). But I'm having trouble understanding the connection.

As I understand, SU(2) is the symmetry group of spinors (as diagrams like this one point out - you need a double-covering of SO(3) in order to cover all spinor-space symmetries). This is why this group is so important in the theory of spin. A question that just occurred to me is why the Pauli matrices happen to form a representation of the Lie algebra su(2); does the algebra of observables of a system always have to be some representation of the system's symmetry group Lie algebra? But we can put that question to one side.

I'm especially confused because the theory of spin in quantum mechanics is usually presented as (a generalised version of) the theory of orbital angular momentum. The commutation relations between spin observables are derived in terms of the canonical commutation relations of linear position and momentum.

So then, could someone connect this intro QM exposition of spin to the groups SU(2) and SO(3)?

I'm also vaguely aware of Clifford algebra representations of spin. As far as I can tell spin states are represented by rotors which happen to double-cover SO(3). But that just kicks the can down the road: why should rotors represent angular momentum?

Apologies if this question is poorly formed or seems scattered - that's because it is. It's hard to form the question exactly because I don't fully understand its subject matter yet. So any answer, even partial, would be greatly appreciated.

submitted by /u/Movpasd
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Do sugared soft drinks contain emulsifiers to keep the sugar in solution?

Posted: 26 Sep 2019 06:22 AM PDT

I heard this random factoid as part of a larger argument against "big food", that soft drinks are supersaturated with sugar so they must also contain an emulsifier, lest the sugar form crystals. I know citrus flavored sodas, e.g. Mtn Dew, Sun Drop, Squirt, contain an emulsifier to keep the citrus oil-based flavors from seperating but I was suspicious of the sugar emulsifiers claim.

EDIT TO ADD If soft drinks don't contain such a product, is there even a foodsafe additive that would allow more sugar to be dissolved in water?

submitted by /u/Skipp_To_My_Lou
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Thursday, September 26, 2019

Why does Sagittarius A* have the * in it's title?

Why does Sagittarius A* have the * in it's title?

Why does Sagittarius A* have the * in it's title?

Posted: 26 Sep 2019 03:18 AM PDT

Always wondered why the * appears in the title. Whenever I see it I keep searching for a footnote at the bottom of the article!

submitted by /u/Backflip101
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Why does some thunder make a boom sound and sometimes it makes a crack/snap sound?

Posted: 25 Sep 2019 09:39 PM PDT

How do you isolate and capture a single atom?

Posted: 25 Sep 2019 05:07 PM PDT

Could someone please explain on how the oxygen we breathe comes from the ocean and not the trees?

Posted: 26 Sep 2019 02:57 AM PDT

Does Continuous Reading on Screened Devices Lead to Worsening Vision?

Posted: 25 Sep 2019 05:51 PM PDT

For example does reading a lot from the screens of iPads, iPhones, laptops or similar devices damage eyesight?

I've looked this question up but haven't found any definitive answers.

submitted by /u/Jpf123
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What type of photodetector is suitable for mid infrared sensing?

Posted: 26 Sep 2019 02:32 AM PDT

What type of photodetector does a typical Raman spectrometer use? Say the spectral range goes from 1200 - 1000 cm-1.

Handheld RM spectrometers like this are fairly cheap (5-10k). I wonder what type of semiconductor they use for sensing.

submitted by /u/dr_meme_69
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Do supergiant stars form all at once or grow from one the size of a 'regular' star?

Posted: 26 Sep 2019 02:17 AM PDT

Does a dead brain still hold information?

Posted: 25 Sep 2019 02:35 PM PDT

I have an idea for a story I want to write but I'm uncertain about the possibilities of a dead brain still retaining the accumulated knowledge from our life. Does it still hold information? If so, is it possible to retrieve that information? If not, then why does it not still hold information, or what are some of the challenges to retrieving that information?

submitted by /u/hafuhafu
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Did medical alcohol or drinking alcohol come first?

Posted: 25 Sep 2019 09:54 PM PDT

This question popped into my head while cleaning a wound on my hand, and it reminded me the time I had to treat a cut with moonshine. But when I tried googling it I just got alot of results about how I shouldn't drink rubbing alcohol. So I'm curious if any of yall would know.

submitted by /u/fudgeking2000
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Why do organ donors and recipients need matching blood types?

Posted: 25 Sep 2019 05:09 PM PDT

Why do organs only function with certain blood types? And is this determined as a foetus or do the organs merely become accustomed to that type of blood throughout the person's life and lose their malleability?

submitted by /u/QuantumDon
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Does brushing your teeth with a plastic toothbrush create micro and nano plastic particles? Could this be the cause of much of the plastic that turns up in our blood and stool?

Posted: 25 Sep 2019 05:57 AM PDT

Are cravings based on what our body wants us to eat, or are they just random?

Posted: 25 Sep 2019 06:40 PM PDT

Why is the formula E^2=(mc^2)^2 + (pc)^2 so similar to the pythagorean theorem?

Posted: 25 Sep 2019 01:05 PM PDT

Why is the formula E2 = (mc2 )2 + (pc)2 so similar to the pythagorean theorem?

submitted by /u/Holsbolsa
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What are some examples of transitional fossils in parrots?

Posted: 25 Sep 2019 07:07 PM PDT

Does the gateway hypothesis for marijuana hold in legal states?

Posted: 25 Sep 2019 05:50 PM PDT

This question has been asked before on here but not specifically restricted to legal states and I have spent about 20 minutes searching for studies on google scholar relating to the topic and did not find anything. Anyways, here is my question:

​

The gateway hypothesis is used as a counter argument to legalize recreational cannabis so it would make sense to check its validity in states where it is legal. The act of buying cannabis in a legal vs illegal state is very different so might introduce unknown variables. So, does the gateway hypothesis for marijuana hold in legal states? I am very curious what you smart folk have to say. Thanks you in advance!

submitted by /u/noelexecom
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Why do planets orbit/rotate in the direction they do?

Posted: 25 Sep 2019 12:00 PM PDT

All of the planets in our solar system orbit the sun in the same direction that the sun rotates about its axis (counterclockwise when viewed from the sun's North Pole). But Venus and Uranus rotate about their axes in the opposite direction as they orbit the sun. What causes planets to orbit another object in a certain direction? Why do none of the planets in our solar system orbit the sun in a clockwise direction? Would it be possible for a planet to orbit in the opposite direction as the sun's rotation? What would cause a planet to rotate about its axis in the opposite direction of its orbit around another object as Venus and Uranus do?

submitted by /u/catmitt98
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how does the space shuttle change direction and stop?

Posted: 25 Sep 2019 03:32 PM PDT

I haven't looked too closely at the space shuttle but I don't see any sideways or backwards facing thrusters. How does it stop, turn or go sideways in space so that it can dock with the ISS?

submitted by /u/forgetfulcoder
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What happens to the heart and blood pressure when someone has to have major body parts amputated?

Posted: 25 Sep 2019 01:25 PM PDT

I was reading a story where someone had both legs amputated and thought about other effects it may have on the human body.

Even if we reach a point where the limbs are near replicas of the original, wouldn't it have some effect on the heart since you aren't pumping as much blood and it not having to travel as far?

submitted by /u/TortugasLocas
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Can nondisjunction occur twice in the same meiotic cycle?

Posted: 25 Sep 2019 04:24 PM PDT

Hi all. Is it possible for nondisjuction to occur at both anaphase 1 and anaphase 2 and result in 4 sets of the X chromosome? In other words, is it possible for both the homologous chromosomes and the sister chromatids to not separate in the same cell cycle and have a resulting gamete with 4 copy's of a the X chromesome? All the examples I have seen say it either occurs in anaphase 1 or anaphase 2.

Thank You!

submitted by /u/ExtraBrilliant
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Wednesday, September 25, 2019

The Gauche Effect. I don't understand how, on the subject of Newman Projections, that the gauche conformation of 2-fluoroethanol, for instance, can be more stable than the anti?

The Gauche Effect. I don't understand how, on the subject of Newman Projections, that the gauche conformation of 2-fluoroethanol, for instance, can be more stable than the anti?

The Gauche Effect. I don't understand how, on the subject of Newman Projections, that the gauche conformation of 2-fluoroethanol, for instance, can be more stable than the anti?

Posted: 24 Sep 2019 06:00 PM PDT

How much protein per 100g of human muscle?

Posted: 25 Sep 2019 01:31 AM PDT

Hey everyone, I'm wondering this because I saw chicken is about 26-33g of protein per 100g and chicken breast is just muscle, which had me wondering what would it be in a human? I am aware it would vary from muscle to muscle but can't find any data online.

I promise I'm not a cannibal.

submitted by /u/Shortbull
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Do fruit plants all share a common ancestor or did multiple fruit plants emerge due to convergent evolution?

Posted: 24 Sep 2019 08:48 PM PDT

If Ice Age floods did all this geologic carving of the American West, why didn't the same thing happen on the East coast if the ice sheets covered the entire continent?

Posted: 25 Sep 2019 07:20 AM PDT

Ask Anything Wednesday - Engineering, Mathematics, Computer Science

Posted: 25 Sep 2019 08:08 AM PDT

Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Engineering, Mathematics, Computer 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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Does boiling 2 cups of water take exactly twice as long as boiling 1 cup of water?

Posted: 25 Sep 2019 05:15 AM PDT

Life is all about organic chemistry. I know about the carbon cycle, but where does the hydrogen come from?

Posted: 25 Sep 2019 05:13 AM PDT

Earth's atmosphere contains hardly any H, it's mostly O and N. My suspicion is that the H comes from water, but that takes a lot of energy!

submitted by /u/meta-wacke
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Could a rogue planet orbit a star?

Posted: 25 Sep 2019 02:35 AM PDT

For example say a rogue planet came into a random solar system, could the planet get caught into the stars gravitational pull and become a regular planet and not a rogue one anymore? This is all assuming rogue planets are floating through space cause I'm not totally sure about that.

submitted by /u/gogospoon
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Does someone's own spoken accent also have the highest listening comprehension?

Posted: 25 Sep 2019 06:59 AM PDT

This question came up while discussing listening to audio with the speed increased to x2-3 original speed and the general comprehension of different accents when speeded up.

I myself find it easier to listen to speech closer to RP (Received Pronunciation) than to my own accent. However I likely understand my own accent better than the average English speaker.

So my question is, how common is it for people to have higher listening comprehension on accents which aren't their own spoken accent? Why does this happen? Is this effect something which is studied or just a weird outlier?

submitted by /u/AnnanFay
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Is there a way to measure a gene's dominance?

Posted: 25 Sep 2019 06:40 AM PDT

So I was thinking about the very basics of genetics I learned at school and stumbled upon this thought, despite not caring much for biology class not understanding this concept still bothers me due to my disliking of randomness.

Can a gene's dominance somehow be determined without specific testing?

My guess would be this, if gene A is dominant over gene B and gene B is dominant over gene C can I assume gene A is also dominant over gene C? so gene A could be assigned a dominance level of 3, B assigned 2 and C assigned 1. Can someone please disprove this for me?

Alternatively maybe genes could be assigned classes, with class A being dominant over class B, class B dominant over class C, class C dominant over class A and D, and class D dominant over class B, so you can assume that if a gene is dominant over class A it must belong to class C hence also dominant over class D. Although this one might be practically impossible to prove due to a potentially infinite amount of classes, so if a gene is dominant over class A it might still not be dominant over class D and instead belong to a new class E.

Is there a more likely theory? perhaps based on experimentation rather then thoughts some kid had while walking his dog? or is this subject rather unexplored and I can't hope for an answer any time soon?

Thanks in advance and sorry if I'm overlooking something and the answer is actually obvious or anything of the sorts.

submitted by /u/SuprOrel
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What is aviation fuel and what makes it different to normal fuel? Is it a different type of chemical compound or is it a special mixture?

Posted: 25 Sep 2019 05:31 AM PDT

Can you still be an organ donor after you’ve had cancer?

Posted: 25 Sep 2019 04:46 AM PDT

Is a zero order relationship even possible?

Posted: 25 Sep 2019 04:44 AM PDT

In school I studied that one of the reactants in a chemical reaction can have a zero order relation to the rate of reaction i.e its concentration does not affect the rate. However, the particle theory states that higher concentration leads to higher no. of atoms per cm^3, therefore a higher number of successful collisions. So, according to the particle theory no reactant can have a zero order relation. Then how does the reaction kinetic theory propose a zero order reaction?

submitted by /u/SamarthRajani666
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Which continents, or areas, are the best for finding fossil records, and why is that so?

Posted: 25 Sep 2019 03:17 AM PDT

So apparently there are no land fossil records from when earth only had one huge continent called Pangaea?

Also if I recall most fossil records come from China or Africa(could be wrong), so I wonder why fossils have survived much better in those areas.

Were other continents more unlivable? or did they go through larger drastic geological changes which destroyed remains?

submitted by /u/worthlesshope
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Why do you think the phanerozoic eon has more divisions and dates than the archean eon?

Posted: 25 Sep 2019 03:17 AM PDT

What is the main factor supporting stability in the proteins of thermophilic organisms? Which amino acids might be more abundant?

Posted: 24 Sep 2019 11:07 PM PDT

To my (potentially incorrect) understanding, thermostable proteins have a high rate of alpha-helices and have smaller loops/turns; thus, the proteins are more compact and the "backbone" is less exposed to potentially damaging temperatures.

Would hydrophobic interactions be the key player in holding the helix/stucture together? Would it be additional H-bonding and attractive forces between the side chains?

I appreciate any insight someone might have!

submitted by /u/monkmonktoodle
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CDC Quarantine, Decontamination and Sterilisation Procedures?

Posted: 24 Sep 2019 10:42 PM PDT

Now I'm certain that any who can answer likely can't say everything but, there is something about the Centers for Disease Control and Prevention (CDC) I have always wondered about.

In a hypothetical worst case accident scenario in a laboratory, what sort of Decontamination and Sterilisation Procedures does/would the CDC institute to prevent deadly pathogens from endangering the public?

Do they have lock down and incinerate procedures like in movies and TV?

submitted by /u/Arohi_rohi
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How do Bose-Einstein Condesates behave? What does it mean for atoms to behave as a single, large collective atom?

Posted: 24 Sep 2019 08:24 PM PDT

What does "Carrier" and "Carrier Free" mean when transporting radioactive solutions?

Posted: 25 Sep 2019 02:03 AM PDT

In my work regarding ionizing radiation and radio-nuclides I noticed that in the majority of cases, radioactive solutions are not transported in their pure form, but they are mixed with another material named a "Carrier".

Can some one please elaborate what is the purpose of this carrier substance and why is it needed?

The only explanation I can come up with is due to physical limitations. For example, if I want to transport 25 [mCi] of Iodine 125, that would translate into around 1.47 10^-6 [g] which means it would require an extremely small container that, I guess, would be very difficult to produce, so the carrier substance provides some kind of a "buffer" without altering the activity of I-125.

submitted by /u/steveraptor
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Can bugs get fat?

Posted: 25 Sep 2019 12:56 AM PDT

Animals are capable of storing energy as fat, is it possible to feed a spider or ant until it's fat. Bees wax is fat but is it possible to store so much of it, it would not be able to fly?

submitted by /u/RexSuperbiae
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Why not "hot air balloon" rockets up before "lift off"?

Posted: 24 Sep 2019 01:51 PM PDT

Is it possible to lift up rockets to the upper atmospheres before using rocket fuel? Or is there just too many variables you can't control from having "lift off" mid air and too many variables you need to align/aligning to do this kind of thing? Ignoring the variables, and it works, does this save a lot of money?

Also I'm not really a scientist/engineer or even a student in any field of science/maths, but I do have a, let's say a hobbyist level understanding of things/intelligence since (forgive me) i graduated not on my peak, and have been stagnant eversince. So have mercy on me with the explanations

submitted by /u/Real_undefined
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How does a "real" echo Dot/Siri/OkGoogle/whatever know not to respond to tv/radio ads that have characters saying their command phrase?

Posted: 24 Sep 2019 11:50 AM PDT

I have an Alexa, and it lights up when it hears someone on tv/radio say her name but it seems to know not to go through with whatever request the ad is telling her to do

submitted by /u/AvengeThe90s
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What impact, if any, does a vaccine have in regards to organ donation? Do vaccinated organs immunize the recipient? Is a non-vaccinated organ more risky than one that has been?

Posted: 24 Sep 2019 11:28 AM PDT
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