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Tuesday, June 28, 2016

AskScience AMA Series: We are Sarah Fortune and Eric Rubin, researchers at the Harvard TH Chan School of Public Health, who study how drug resistance evolves in bacteria, and we’re here to answer your questions!

AskScience AMA Series: We are Sarah Fortune and Eric Rubin, researchers at the Harvard TH Chan School of Public Health, who study how drug resistance evolves in bacteria, and we’re here to answer your questions!


AskScience AMA Series: We are Sarah Fortune and Eric Rubin, researchers at the Harvard TH Chan School of Public Health, who study how drug resistance evolves in bacteria, and we’re here to answer your questions!

Posted: 28 Jun 2016 05:02 AM PDT

Science AMA Series: We are Sarah Fortune and Eric Rubin, researchers at the Harvard TH Chan School of Public Health, who study how drug resistance evolves in bacteria, and we're here to answer your questions!

Hi, reddit!

We are Sarah Fortune and Eric Rubin, researchers at the Harvard TH Chan School of Public Health. Although our research focuses on tuberculosis, we are generally interested in how drug resistance evolves in bacteria and how we can subvert the development of resistance.

Antibiotics have helped reduce infectious diseases, particularly those caused by bacteria, from one of the most common causes of death to diseases that are mostly completely curable. However, as each new antibiotic has been developed, resistance to each has slowly or, in some cases, rapidly emerged. There have been some cases that are highly publicized, including the recent infection of a woman with a strain of bacteria that was resistant to a rarely-used but useful last ditch antibiotic, colistin. This case, in Pennsylvania, was the first example of this type of resistance mechanism in the US. But antibiotic resistance is increasing throughout the world, both in hospitals, which have long harbored highly resistant organisms, and in community settings.

How much of a threat is this? What can we do about it?

We'll be back at 3 pm EST (noon PST, 8 pm UTC) to answer your questions, ask us anything!

submitted by /u/HarvardChanSPH
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I remember during the 90s/00s that the Ozone layer decaying was a consistent headline in the news. Is this still happening?

Posted: 27 Jun 2016 07:36 AM PDT

If I didn't know how old I was and there was no documentation, how could my age be determined and to what degree of accuracy?

Posted: 27 Jun 2016 04:50 PM PDT

Watts, Voltage, and Amperes What are they?

Posted: 28 Jun 2016 04:18 AM PDT

The title is a bit misleading as I do know what they are but I don't entirely understand them. I have a test in Science class soon, however, taking a look back at my notes, I feel like I overcomplicated everything and am feeling confused.

I understand that Watts is the outcome of power or J/S. I know that electrons actually move slower than snails but what we generally mean is the voltage drop. I know that Voltage*Amperes=Watts

I'm not sure what volts (or voltage) are. I'm not entirely sure what a voltage drop is, is it a constant burst of energy or is it just electricity moving? Are watts per second? If I left a 20W lightbulb running for an hour and I have to pay 18c per kWh, how do we figure out how much money that costs?

submitted by /u/OtterlyGaming
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Why do diesel and petrol/gas exhausts gasses differ so much at high revs?

Posted: 28 Jun 2016 05:44 AM PDT

I've long wondered why when a petrol/gas car idles you see a visible white exhaust which becomes clear or invisible when the engine is revved, where as when a diesel engine idles it's generally not visible, but when it's revved it turns into a thick black exhaust?

submitted by /u/jolyon_russ
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Glasses do limit the field of view in which the wearer can perceive details. Does this limitation/restriction influence the development of the brain in children?

Posted: 28 Jun 2016 05:38 AM PDT

The development of a child seems to be influenced by pretty much everything to one degree or another, and so I was asking myself the question: do glasses influence their wearer?

The stereotype of the intelligent glasses wearing student is as old as the glasses themselves, and I always wondered if there was some truth to it. If I recall correctly no link between IQ and wearing glasses or not was found (why would there be), but I thought of something else:

Restricting one's field of view would force a person to focus on less things at once. The brain is only capable of analyzing so much data, maybe limiting the amount of detail in view at every given moment has an influence on how much 'processing power' is left for the remaining information.

If that is the case, then starting to wear glasses at an early point in life would probably shape the way we deal with visual information for the rest of our lives, wouldn't it?

Has there been research on this topic? I would appreciate pointers into the right direction

Edit: I picked the neuroscience flair, but I'm not actually sure if that's the correct category.

submitted by /u/FriendsCallMeAsshole
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How common is iron on a cosmic scale?

Posted: 28 Jun 2016 05:20 AM PDT

Why does heat seem to make things shimmer? Why does it form the mirage?

Posted: 28 Jun 2016 01:31 AM PDT

If amphetamines and opiates both work by overstimulating dopamine production, why are their effects on the body almost polar opposites?

Posted: 27 Jun 2016 11:40 AM PDT

Why did it take painters so long to 'discover' the rules of perspective?

Posted: 27 Jun 2016 11:59 PM PDT

[Physics] If two songs (one at 50db and another at 30db) are playing at once, what is the total loudness?

Posted: 28 Jun 2016 04:36 AM PDT

Just wondering because I'm a hypochondriac who worries about ear issues. I had been listening to music at 50 - 60db for an hour without realizing that I had a shuffle playlist on around 20 - 30 db the entire time. Also wondering if damage is possible from that.

submitted by /u/TomOfBlades
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Why was a part of NASA's observation satellite's, Landsat 8, mission overview to share data to the general public on a nondiscriminatory basis at no cost to the user?

Posted: 28 Jun 2016 01:41 AM PDT

What is with up with using words like large and very large in the names of telescopes and detectors? Is it a running joke?

Posted: 28 Jun 2016 03:52 AM PDT

Why not give these things (like the LHC) a resounding title, like "The People's Glorious Ringed Collider" or for the VLT, the "Unblinking Eye Into The Eternal Void"? Or just something like, you know, Hubble.

submitted by /u/damondefault
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If you have cancer and begin starving, does cancer growth slow?

Posted: 27 Jun 2016 06:02 PM PDT

Similarly, does eating at a large caloric excess increase the speed of cancer growth?

submitted by /u/FourthLife
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Does the fact that the total intrinsic mass quarks in a proton only makes up a tiny bit of it's mass, mean if we "turn off" the higgs field we would still have protons (and matter) only lighter ??

Posted: 28 Jun 2016 06:37 AM PDT

Assuming you could get a good running head start and properly time it, would tackling a person sideways while they are falling help prevent injury/death?

Posted: 27 Jun 2016 06:00 PM PDT

So lets say there's someone who's suicidal and planning to jump from a building and you have some time to prepare yourself. If you are able to tackle them sideways would that decelerate them at all? Or would it just add horizontal velocity to their vertical velocity? Logically I'm thinking the latter of the two but when trained to fall from heights you try to roll out of them, a.k.a changing the direction of your momentum. So I'd assume a tackle would just be a sloppy version of a technical roll.

submitted by /u/Truesoldier00
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Is bone marrow always making blood cells? If yes, what is causing old cells to go away? If no, what starts and stops the process?

Posted: 27 Jun 2016 09:58 PM PDT

Can a city affect the weather?

Posted: 27 Jun 2016 04:32 PM PDT

If a giant storm is heading towards a city can the city affect the storm? I've watched many times on radars as storms seem to bubble around larger cities. Where I'm from they just refer to it as the "Lubbock effect" but I'm wondering if the city may actually be the cause.

submitted by /u/KingoftheCrackens
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What is so special about the genetic structure of Orchids that they can hybridise so freely while retaining significant fertility.

Posted: 27 Jun 2016 12:54 PM PDT

Orchids really sort of stand out in this respect. While in other organisms, hybridization will at most involve a handfull of closely related species, with relatively rare preservation of fertility, orchid breeders routinely pump out not just interspecific, but even intergeneric hybrids with relative ease. Such complex crosses have led to artificial poly-genera such as Potinara (Brassavola x Laelia x Cattleya x Sophronitis) or even outrageous things combining input from up to 7 different genera as in Masonara (Aganisia × Batemannia × Colax × Otostylis × Promenaea × Zygopetalum × Zygosepalum). It is far from unusual for individual plants to have such a complex history of hybridation behind them they might as well be called genealogies...

And these intergenerics all seem to be relatively freely breedable with one another, provided one remains in the same alliance.

So why, and mostly how, is this possible? What is so special about orchid genomes that such artifical hybridation is possible without significantly reducing fertility?

submitted by /u/Gargatua13013
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[Biology][Chemistry] What is the science behind skincare products? Is there really a reason to use face wash instead of soap on your face?

Posted: 27 Jun 2016 11:04 AM PDT

We have all heard the pH story, marketing that claims soap is too aggressive etc. But is there any scientific research that actually justifies skincare products? Or is it all just clever marketing?

submitted by /u/TheyTukMyJub
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How can we reliably tell the difference between male and female voices?

Posted: 27 Jun 2016 02:13 PM PDT

Is it just tone (high for female, low for male), or is it more complex than this? Do transitional hormonal therapies change voices so that they become more reliably identifiable as the new sexual identity?

submitted by /u/paetrixus
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Why does the behavior of an airflow going through a nozzle changes between subsonic and supersonic speeds?

Posted: 27 Jun 2016 04:45 PM PDT

I'm currently follow an aircraft technician course and, during the engine section, we see how a turbine engine works and how the airflow is affected by convergent and divergent nozzles at subsonic and supersonic speeds. However, my classmates and I cannot quite understand why the air behaves differently between those two speed ranges, so if anyone could help us understand better this would be very much appreciated.

submitted by /u/firefly_12
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Is there a field for Weak Nuclear Force and Strong Nuclear Force?

Posted: 27 Jun 2016 04:24 PM PDT

I also learned that Coulomb's Law parallels Newton's gravity equation. Is there a similar equation for Strong and Weak Nuclear Force?

submitted by /u/Scezory
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Monday, June 27, 2016

I'm making jelly and the instructions say: "Do not add pineapple, kiwifruit or paw paw as jelly will not set." Why is that?

I'm making jelly and the instructions say: "Do not add pineapple, kiwifruit or paw paw as jelly will not set." Why is that?


I'm making jelly and the instructions say: "Do not add pineapple, kiwifruit or paw paw as jelly will not set." Why is that?

Posted: 26 Jun 2016 06:06 PM PDT

What effects does a pear-shaped nucleus actually have on an atom? And what causes it?

Posted: 27 Jun 2016 06:00 AM PDT

I just saw this post in /r/science which talks about a pear-shaped nucleus. There was an article linked, but it was a bit above my understanding.

So given that I was always told that an atom's nucleus is spherical, what do different shapes mean?

submitted by /u/Tridian
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When children need an organ donor, must the donor be of a similar size to them or can an adult donate? Will the organ continue to grow as the child grows?

Posted: 26 Jun 2016 12:23 PM PDT

How much more mass would Jupiter require to begin the fusion process? And how much volume would it gain if it were to start?

Posted: 27 Jun 2016 06:48 AM PDT

What is the difference between sand in Mars and Sand on Earth?

Posted: 27 Jun 2016 05:04 AM PDT

I've been looking at pictures of Mars and the sandy surface looks eerily similar to deserts on Earth. If we compare granule to granule, how different would the Mars sand be to Earth sand in terms of composition?

submitted by /u/vjmech
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Where do photons come from?

Posted: 26 Jun 2016 04:17 PM PDT

For example, if you were in a dark room and you lit a match, where do the photons come from? Were they dormant in the room, or stored somehow in the chemicals of the match?

submitted by /u/nojbro
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Is the fact that we only see one side of the moon an incredible coincidence or is there some sort of phenomenon going on?

Posted: 26 Jun 2016 06:09 PM PDT

If I was standing on mars for a lunar month (or any planet really) would I always see one side as well?

submitted by /u/FantasticEggplant
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How does a magnetic field form and how does Earth's magnetic field compare to other known planets with one?

Posted: 26 Jun 2016 06:47 PM PDT

Have any bacteria developed alcohol resistance in the same way as antibiotic resistance?

Posted: 26 Jun 2016 12:31 PM PDT

Is there any correlation between prefered school subject and political beliefs?

Posted: 26 Jun 2016 06:35 PM PDT

Something that has been on the mind for awhile, but I can't seem to find any studies nor information on the subject. I have a feeling there is possibly some correlation, but I can't be too sure. Anyone have any information on this subject?

Also, this might not be science related per say, so redirect me to where I should post if not!

Thanks!

submitted by /u/Storm_Shaker
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Is there any way to measure/define smell that isn't purely allegory?

Posted: 26 Jun 2016 07:06 PM PDT

We measure the stimulus of all other senses: light, sound, pressure, temperature, taste, etc. Is there any form of measurement for smells?

submitted by /u/sa3r3t
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Do elementary particles have shape?

Posted: 26 Jun 2016 04:49 PM PDT

What's the science behind pickling?

Posted: 26 Jun 2016 11:14 PM PDT

I just want to know why soaking a cucumber (or whatever you pickle) in vinegar and seasonings prevents it from going bad over a much longer scale.

submitted by /u/OgEScissors
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Why does gravity assist work?

Posted: 26 Jun 2016 07:55 AM PDT

I understand what gravity assist is but I do not understand why the object using the gravity assist gains so much energy after passing into and out of somethings SOI. Wouldn't the object in question lose just as much energy as it gained falling towards the body as it would traveling out of it's SOI? Educate me please.

submitted by /u/KetsuoRotsuda
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Could a gun be used to propel a spacecraft while it's in space?

Posted: 26 Jun 2016 06:18 PM PDT

I remember reading that it's possible to shoot a gun in space (they tested shooting a gun in a vacuum on MythBusters as well), and that by doing so you would be propelled back by it. I also remember a thread saying that it's possible to propel yourself in space by throwing a rock.

What if a gun, or a ballistics device was mounted to propel a space shuttle? Could it propel it at a fast speed? Would the size of a spacecraft play a part in how fast it could go?

submitted by /u/AgentJin
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Would Adding Spin to a Rocket Improve Stability?

Posted: 27 Jun 2016 03:19 AM PDT

When throwing a football, adding a spin to it seems to improve stability. Would the same be true for for something like a rocket which is much faster and heavier?

submitted by /u/THatoneguy720
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How does LIGO differentiate what kind of movements are caused by things they're trying to study, like gravitational waves, and normal seismic activity?

Posted: 26 Jun 2016 07:12 PM PDT

I just watched this video and it does a great job explaining how LIGO works, but it begs the question, how do you cancel out the noise from normal Earthly things? A machine that sensitive would be able to measure even the smallest earthquakes anywhere on earth wouldn't it?

submitted by /u/imatmydesk
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Can hybrids reproduce?

Posted: 27 Jun 2016 02:37 AM PDT

I've always been taught that hybrids, such as the mule, are infertile and therefore cannot reproduce. However, I've read that Lemons are a hybrid between a citron and a sour orange (which is itself a hybrid of a pomelo and a mandarin). I also believe there are hybrids between Cannibis species. Is this a strictly plant thing or can some animal hybrids reproduce?

submitted by /u/_smorgas_
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If the Earth rotates on an axis, and the Earth also rotates the sun, why is the North Star always visible?

Posted: 26 Jun 2016 01:54 PM PDT

Question was brought up at work, can anyone explain?

submitted by /u/MercuryCalled
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Why do two like charges moving in the same direction have magnetic forces that are directed towards the other?

Posted: 26 Jun 2016 05:15 PM PDT

My question is similar to asking 'Why do two wires with current flowing in the same direction attract each other, and two wires with current flowing in opposite direction repel?' However, I can somewhat comprehend the reason for this. What I don't understand is how, for example, two positive charges traveling parallel to each other will have a magnetic force that tries to pull them together.

submitted by /u/Somnies
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If rust is just oxidized metal then why can rusty metal transmit tetanus (a bacteria)?

Posted: 26 Jun 2016 10:42 AM PDT

I've never heard of someone getting tetanus from clean metal so what about rusted metal is different?

submitted by /u/scrubs2009
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Do rays of light have any effect on each other, when they intersect?

Posted: 26 Jun 2016 11:13 PM PDT

Sunday, June 26, 2016

A few questions regarding the asteroid orbiting Earth NASA just announced..?

A few questions regarding the asteroid orbiting Earth NASA just announced..?


A few questions regarding the asteroid orbiting Earth NASA just announced..?

Posted: 25 Jun 2016 07:09 PM PDT

NASA announced last week they had discovered a "quasi-satellite" that has been orbiting Earth for an unspecified amount of time.

So, I have lots of questions regarding this, many probably unanswerable.

Could it collide with the moon? How could this affect things like our tides?

How long has it been there? Could this arise in a matter of decades, or has it probably been there for centuries, millennia, or longer?

Could we land our own satellites on it and take advantage of its apparently rather stable orbit? Would it be affecting our tides or weather at all?

Could we see it with the naked eye, or with any at-home tech, any time soon?

I presume it's unlikely to hit Earth anytime soon, looking at the article. How unlikely?

Could it be mined for minerals?

If anyone educated or experienced in anything related to this has any information, or even any guesswork, related to these questions, or even any more interesting info, I'd love to hear it :) I'm not used to being unable to google something and read pages of information on it, haha!

Feel free to answer just one question, or even provide more info completely unrelated to my questions.

Edit: RIP inbox. My mother always said I ask too many questions for my own good.

submitted by /u/Omfinite
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If my body is already completely hydrated and I drink 16 oz of water, will I eventually pee out 16 oz of straight water (if my bladder is completely empty)?

Posted: 25 Jun 2016 08:42 PM PDT

Is there a limit to the amount of diseases we can be immune to? Can our collection of memory T-cells run out of memory?

Posted: 26 Jun 2016 03:16 AM PDT

Say one was given a viable vaccine regimen to all of the current diseases in the world, and no new strains/diseases arose. Would one be able to remain immune to all disease in the world?

From my understanding, the majority of the memory T-cells in our body are naive, not yet exposed to pathogen. However, would the amount of memory T-cells in our body be able to efficiently maintain a database of all known diseases and maintain immunity?

submitted by /u/larsonmarson
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Why do clouds form when you mix liquids of different densities?

Posted: 26 Jun 2016 05:18 AM PDT

Hi, I have a quick question: why when you mix liquids of different densities (acid and water, sirup and water) you see "clouds" where the two liquids are mixing?

submitted by /u/CzechAstronomer
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Are certain languages more adequately equipped to facilitate effective and efficient communication in the Information Age?

Posted: 26 Jun 2016 04:39 AM PDT

I'm wondering if there are facets of languages such as roots, abbreviations, and word length that have allowed the Information Age to progress faster into the culture of the native speakers? If so, which languages and why?

submitted by /u/leanord12
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How much bigger is the Great Pyramid of Giza in the hottest temperatures compared to the coldest?

Posted: 26 Jun 2016 04:39 AM PDT

Why do chip manufacturers not design hexagonal chips for more yield from round silicone wafers?

Posted: 26 Jun 2016 04:36 AM PDT

Under optimum conditions what actually limits plants growth rate?

Posted: 26 Jun 2016 04:30 AM PDT

If a plant is getting the perfect amounts of everything it requires, what limits the growth rate? is there any way we could develop super-fast growing vegetables?

submitted by /u/zomzilla
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So, scientifically speaking, why is it that one's knees go weak upon an amorous interaction with someone?

Posted: 26 Jun 2016 01:12 AM PDT

In terms of weakness in general, why do humans feel it at times? Is it to appreciate strength more? I'm not meaning to get all philosophical here.

submitted by /u/VirgoGeminiCancer
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Would the asteroid belt eventually form a new planet?

Posted: 26 Jun 2016 02:43 AM PDT

Why did Obesity only start to increase after 1990?

Posted: 26 Jun 2016 02:40 AM PDT

What happened after 1990 that caused obesity to increase? The break up of the USSR?

submitted by /u/shewontbesurprised
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Can we synthesise snake or other animals' venom?

Posted: 26 Jun 2016 05:53 AM PDT

How does the maths for fission/fusion and binding energies work out?

Posted: 26 Jun 2016 05:17 AM PDT

I've never quite been able to work out how the binding energies for fission and fusion make sense. I know the graph for binding energy per nucleon, and I understand it has something to do with that, but I can't help but find that the mass defect equations don't make sense.

As an example for what I'm trying to understand, I'll use the classic deuterium-tritium fusion equation:

H2 + H3 -> He4 + n + 17.6MeV

Total number of neutrons remains constant, so there's no mass difference there, and total number of protons is the same, so same total mass either way.

But for binding energy:

2.224573MeV + 8.481821MeV -> 28.295674MeV 

So as a result, the total mass-energy in the equation increases by 17.58928MeV. Since the total energy has to remain constant, doesn't this mean that the system absorbed that 17.6MeV?

I'm certain that this line of thinking is wrong somewhere. I used this website for the numbers, and I'm not concerned about the actual numbers. I just don't understand how the system both apparently increases in mass-energy and releases mass-energy. Shouldn't the original equation be:

H2 + H3 + 17.6MeV -> He4 + n

Once again, I know this is wrong. I'm just not sure how.

submitted by /u/never_pessimistic
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What is the margin of error of the Brexit referendum?

Posted: 26 Jun 2016 05:15 AM PDT

Assuming that a vote or election is just a survey of a really biased sample of the population, how sure can lawmakers be that the decision reflects the opinion of all eligible voters?

submitted by /u/blinkenpilz
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Why can't we use space to see our history?

Posted: 26 Jun 2016 05:12 AM PDT

I know a bit about science however it's not much. I was wondering what would stop us using the reflection of light off objects in space from seeing the out past

For example if want to see 2000 and by chance there was an asteroid reflecting light 8 light years away what would stop you using the reflection to see it.

I don't know if this is a stupid question but would love to know why I'm stupid I do.

submitted by /u/Send_ass_pics247000
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How (un)likely is it that an unpredictable catastrophic astronomical event will hit earth?

Posted: 25 Jun 2016 08:44 AM PDT

The earth has been around for a seemingly very long time, without (for example) being hit by an asteroid so large that we're just obliterated. How likely is it that an event like this could occur without us having any chance to even be aware of it?

submitted by /u/mangotiger
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Insects don't have eyelids. How do the diurnal ones not get blinded by the sun?

Posted: 25 Jun 2016 09:46 AM PDT

What are efficient chemical substances that are effective against flees and how do they work?

Posted: 26 Jun 2016 04:30 AM PDT

To be specific: cat flees

There is a lot of misinformation around the Internet. Maybe someone with a scientific background could shed some light on this topic?

Is not the most scientific question, but I don't think I'll get an honest answer anywhere else.

Thanks in advance!

submitted by /u/Justify_87
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How do tiny ants produce their distress calls?

Posted: 26 Jun 2016 12:38 AM PDT

I used to catch bees a lot as a child. I'd sometimes get one pinned against whatever I was catching it with, say the lid of a Cool Whip container, and it would make a distressed sounding buzz. I assumed back then that it was the sound of the bee trying to fly its way out of its predicament.

Fast forward to a couple years ago when I had a column of little brown ants going through my basement. I stretched out on the floor to watch them at work, and at one point pulled up a bit of linoleum they were going through to watch what they were doing there. When I released it, it curled back down and pinned an ant under it. It immediately started making a sound very similar to that of a trapped bee, albeit considerably higher in pitch and lower in volume.

Are these distress calls? How are they made? I assumed that the bees were vibrating their wing muscles to make the noise, but worker ants never have wings.

submitted by /u/FeculentUtopia
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Why are the yarns in a rope twisted? Does it increase tensile strength?

Posted: 26 Jun 2016 04:23 AM PDT

Why NPSH takes stagnation pressure into account and not just static pressure?

Posted: 26 Jun 2016 03:47 AM PDT

Why NPSH takes stagnation pressure into account and not just static pressure?

According to the formula: NPSH = (Static pressure + Dynamic pressure)@inlet - Vapor pressure

So, if static pressure if way below vapor pressure but fluid is moving really fast, there might not be a high risk of cavitation. So it means that even though fluid is way below vapor pressure he's obviously not boiling?

Why formula for NPSH isn't NPSH = (Static pressure)@inlet - Vapor pressure?

submitted by /u/The-Absentee
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Can I estimate the sound level in -dB from the distance between ripples in a glass of water at the position of the listener?

Posted: 26 Jun 2016 03:46 AM PDT

If so, what would be lowest limit one could physically measure?

I'm aware there are better ways of measuring the sound level, I'm just curious if it could be done with rudimentary tools and some rational thinking.

submitted by /u/Elehphoo
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How is it when we hold our breath, we sink in water, yet a dead body floats?

Posted: 25 Jun 2016 07:00 PM PDT