Why is there a time-energy uncertainty relation when time is not an operator in Quantum Mechanics?

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• Why is there a time-energy uncertainty relation when time is not an operator in Quantum Mechanics?
• If there is an infinite amount of natural numbers, and one is chosen at random, mathematically the probability of choosing that number should be 0. Why can the number still be chosen?
• How are satellite orientated in space?
• Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science
• How do we measure the temperature of stars and quasars up to 100,000,000°? How do we know it's that hot?
• How does a high pass filter (RC) still pass high frequencies when actively charged to input voltage by the DC component?
• How do 17 year life cycle cicadas "keep track" of the year count to know when to emerge?
• How do cell regeneration rates vary among animals? Would it take a dog longer than a cat or human to replace most of the cells in its body?
• Can the CBD part of cannabis influence your reaction time?
• Besides preventing fires, what impacts do fire retardants dropped from planes onto wildfires have on the environment?
• Why do epithelial cells line the outsides of organs that never experience external stimuli?
• If I were to throw or shoot something downwards at a velocity greater than its terminal velocity, would it decelerate until it reached the terminal?
• How does an extended release pill work?
• How are old films restored?
• How come there is no motion blur in google street view photos?
• Why are some medicines more bioavailable than others before or after a meal?
• What does it mean to "burn out a motor," exactly?
• creating better water pressure with a siphon?
• Where did all the dirt on top of dinosaur fossils come from?

Why is there a time-energy uncertainty relation when time is not an operator in Quantum Mechanics? Posted: 13 Nov 2018 10:58 PM PST The Heisenberg Uncertainty Principle is based on the property of the commutators of two Hermitian operators. But time is not an operator in Quantum Mechanics, so what gives? How fundamental is this relation? Where does it come from and what does it mean? submitted by /u/lAPPYc [link] [comments]

If there is an infinite amount of natural numbers, and one is chosen at random, mathematically the probability of choosing that number should be 0. Why can the number still be chosen? Posted: 13 Nov 2018 01:57 PM PST It seems fairly reasonable that the probability cannot be 0, as if you were to sum up all the probabilities, you have to get one as a result, while the sum 0 + 0 + 0 + ... + 0 + 0 (with an infinite amount of zeros) can never have any other value than 0. But, the probability of choosing a specific number should be 1/(amount of natural numbers), which is 0, since the amount of natural numbers is infinite. Is it something about how the limit of 1/x for x -> infinity works, or am I missing something else entirely? submitted by /u/Scutman [link] [comments]

How are satellite orientated in space? Posted: 14 Nov 2018 12:39 AM PST If down is relative to the ground for us how is positioning treated in space? submitted by /u/Biboomer97 [link] [comments]

Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science Posted: 14 Nov 2018 07:11 AM PST Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Physics, Astronomy, Earth and Planetary Science Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical /r/AskScience post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...". Asking Questions: Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit /r/AskScienceDiscussion , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists. Answering Questions: Please only answer a posted question if you are an expert in the field. The full guidelines for posting responses in AskScience can be found here. In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for /r/AskScience. If you would like to become a member of the AskScience panel, please refer to the information provided here. Past AskAnythingWednesday posts can be found here. Ask away! submitted by /u/AutoModerator [link] [comments]

How do we measure the temperature of stars and quasars up to 100,000,000°? How do we know it's that hot? Posted: 13 Nov 2018 05:53 PM PST submitted by /u/Obdurodonis [link] [comments]

How does a high pass filter (RC) still pass high frequencies when actively charged to input voltage by the DC component? Posted: 14 Nov 2018 06:26 AM PST I have an understanding of why capacitors block DC and pass AC but i don't fully understand how this works with a mixed signal input on a parallel plate capacitor, AC is passed due to low plate charge accumulation but with a mixed signal the plate should remain charged and block AC too, can anyone help me to understand this? submitted by /u/OnAPaleNarwhal [link] [comments]

How do 17 year life cycle cicadas "keep track" of the year count to know when to emerge? Posted: 14 Nov 2018 05:59 AM PST submitted by /u/Malak77 [link] [comments]

How do cell regeneration rates vary among animals? Would it take a dog longer than a cat or human to replace most of the cells in its body? Posted: 13 Nov 2018 07:22 PM PST submitted by /u/dance_apoptosistic [link] [comments]

Can the CBD part of cannabis influence your reaction time? Posted: 14 Nov 2018 01:26 AM PST Hello, I've been reading up on some of the functions of the endocannabinoid system, but I haven't found anything on all of the internet having to do something with CBD? I find plenty of experiments or scientific works talking about the influence of THC and it's effects, while with CBD I only find things such as it's healing effects and nothing about reaction time, nothing with the endocannabinoid system about reaction time either. Excuse my grammar, simply an article would also be of great help :) submitted by /u/darthvale [link] [comments]

Besides preventing fires, what impacts do fire retardants dropped from planes onto wildfires have on the environment? Posted: 13 Nov 2018 02:56 PM PST In California right now, fire planes are dropping fire retardants to help manage the wildfire burns. Obviously, one impact this has on the environment is minimizing the amount of fire. What other environmental impacts are there? Does it hurt or help animals or plants, air or soil? *I added "chemistry" flair since it's a chemical, but I imagine this involves other areas too... submitted by /u/forcedguy [link] [comments]

Why do epithelial cells line the outsides of organs that never experience external stimuli? Posted: 13 Nov 2018 05:43 PM PST Why are some cells called endothelial and some epithelial? I read that epithelial cells are cell that cover outsides of the organs and body. Lot of organs never experience the external stimuli yet they have epithelial tissue. Is my understanding of epithelial tissue wrong or is there more to it? submitted by /u/karrablaster123 [link] [comments]

If I were to throw or shoot something downwards at a velocity greater than its terminal velocity, would it decelerate until it reached the terminal? Posted: 13 Nov 2018 03:58 PM PST submitted by /u/rygy267 [link] [comments]

How does an extended release pill work? Posted: 13 Nov 2018 04:27 PM PST For example I'm on a pill that is 100mg ER, so is the pill 100mg and it just gives you small amount over a certain time, or is the pill alot more, and gives you a constant 100mg in your system? submitted by /u/bigz3012 [link] [comments]

How are old films restored? Posted: 13 Nov 2018 02:27 PM PST I just saw a thing about a documentary being restored from WWII in colour, and it made me wonder how exactly they do that? Edit: not sure if that's the right tag but I'm just curious about this... submitted by /u/toy_machine21 [link] [comments]

How come there is no motion blur in google street view photos? Posted: 13 Nov 2018 02:12 PM PST So i was just going down some random highway on Google Street View and started thinking about if the car had to stay under a certain speed to get a good quality photo and then I realized that none of the photos were blurry even though the pictures were taken at or above 50mph. this may be a very simple trick that most photographers know but I don't know very much about cameras so its something that I'm unable to figure out. submitted by /u/fourkcchiefs [link] [comments]

Why are some medicines more bioavailable than others before or after a meal? Posted: 13 Nov 2018 05:43 PM PST submitted by /u/numquamsolus [link] [comments]

What does it mean to "burn out a motor," exactly? Posted: 13 Nov 2018 07:32 AM PST I have an ice cream maker and the manual has several warnings about not letting it run for too long. In particular, I'm not supposed to let the ice cream freeze to the point where it stops the mixing blade from moving since this will cause damage to the motor. So today I've done that, and there's strong burnt smell coming off of it now. Very distinct. It still seems to work, but I'm wondering how much damage I've done. submitted by /u/PM_your_cats_n_racks [link] [comments]

creating better water pressure with a siphon? Posted: 13 Nov 2018 08:54 AM PST It seems crazy that this isn't something that's done regularly, so I bet it won't work, but: in an attempt to get more water pressure through a pipe/hose than would happen if the hose is hooked to the bottom outlet of a tank, what if I were to create a siphon, but put the siphon hose way up high? As though the side of the tank were at the max (10 meters). Would the water coming out the hose, just slightly below the floor of the tank have MORE pressure than it would if it was just flowing out? That is, would the drop in height from the 2nd half of the hose create more PSI? Practical scenario: a tank just slightly above a house that needs good pressure. hang a hose a couple stories up in a tree, create a siphon. would the house get better water pressure? submitted by /u/Tyssniffen [link] [comments]

Where did all the dirt on top of dinosaur fossils come from? Posted: 13 Nov 2018 03:10 PM PST submitted by /u/Upstairs_Cow [link] [comments]

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If Hubble can make photos of galaxys 13.2ly away, is it ever gonna be possible to look back 13.8ly away and 'see' the big bang?

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• If Hubble can make photos of galaxys 13.2ly away, is it ever gonna be possible to look back 13.8ly away and 'see' the big bang?
• AskScience AMA Series: I'm Carlos Zarate Jr., and my research team at the National Institutes of Health Intramural Research Program works on new, fast-acting therapeutics for treatment-resistant depression, bipolar disorder, and suicidal thinking. AMA!
• What was/is the actual damage from plastic microbeads?
• Why is the Milwaukee protocol not recommended?
• Why does Turner syndrome have consistent symptoms when the X chromosomes should be redundant?
• Do people with lots of kids have better immune systems due to constantly getting sick?
• Why are parasites considered true living organisms while viruses are not?
• Where did all the water on asteroids come from?
• How do fertility/sperm tests work?
• Is there a limit on the number of radio telescopes that may be networked together?
• Were there wild pigs or were they breed from domesticated boars?
• Is Tungsten Carbide an alloy?
• If solar sails are possible, why EM Drive isn't?
• Is this a reasonable simulation of tension across a hanging rope?
• Questions about behavior of electrons in an atom?
• How does angiotensin 2 affect GFR?

If Hubble can make photos of galaxys 13.2ly away, is it ever gonna be possible to look back 13.8ly away and 'see' the big bang? Posted: 13 Nov 2018 01:21 AM PST And for all I know, there was nothing before the big bang, so if we can look further than 13.8ly, we won't see anything right? submitted by /u/-SK9R- [link] [comments]

AskScience AMA Series: I'm Carlos Zarate Jr., and my research team at the National Institutes of Health Intramural Research Program works on new, fast-acting therapeutics for treatment-resistant depression, bipolar disorder, and suicidal thinking. AMA! Posted: 13 Nov 2018 04:53 AM PST My name is Carlos Zarate Jr., and I am the Chief of the Experimental Therapeutics and Pathophysiology Branch and the Section on the Neurobiology and Treatment of Mood Disorders at the NIH's National Institute of Mental Health (NIMH). In 2016, more than 1 in 20 American adults and 1 in 10 adolescents experienced at least one major depressive episode. Depression can massively affect people's lives, removing the pleasure they receive from their hobbies and social interactions and reducing their ability to work. In the most severe cases, individuals who suffer from depression tragically choose to end their lives - suicide was the 10 th leading cause of death overall in the U.S. in 2016, claiming nearly 45,000 lives, and it is the second-leading cause of death among Americans ages 10 to 34. In fact, in that year, there were more than twice as many suicides in the U.S. as homicides. The medications currently available to treat depression typically take up to six weeks to start having full effects. To improve treatment and accelerate symptom relief, my research focuses on developing new medications for this often-debilitating condition, along with identifying new potential drug targets and objective measures called biomarkers that yield information about how a patient is responding to treatment. In recent years, my lab has extensively investigated and assessed the effects of the anesthetic drug ketamine on depression and suicidal thoughts. Many of the patients in our trials have had marked and rapid responses to ketamine, sometimes within a single day or just a couple of hours. We have also made major headway in determining how ketamine produces such dramatic changes so quickly. However, because ketamine can have serious side effects, we are working to identify ketamine-like drugs with similarly rapid effects but fewer problematic side effects. For more information on my work, check out this story and video on the NIH Intramural Research Program (IRP) website: https://irp.nih.gov/our-research/research-in-action/from-despair-to-hope-in-hours. You can also read my investigator profile at https://irp.nih.gov/pi/carlos-zarate. If you or someone you know is in crisis and needs immediate support or intervention, call the National Suicide Prevention Lifeline at 1-800-273-8255. Trained crisis workers are available to talk 24 hours a day, 7 days a week. Your confidential and toll-free call goes to the nearest crisis center in the Lifeline national network. These centers provide crisis counseling and mental health referrals. You can call for yourself or on behalf of a friend. If the situation is potentially life-threatening, call 911 or go - or assist a friend to go - to a hospital emergency room. Lives have been saved by people taking action. AskScience Note: As per our rules, we request that users please do not ask for medical advice. Please see above for specific actions to take in the event of a situation. submitted by /u/AskScienceModerator [link] [comments]

What was/is the actual damage from plastic microbeads? Posted: 13 Nov 2018 06:20 AM PST submitted by /u/PHealthy [link] [comments]

Why is the Milwaukee protocol not recommended? Posted: 13 Nov 2018 01:15 AM PST The Wikipedia page about rabies states the following three things. About the disease itself, it says: In unvaccinated humans, rabies is almost always fatal after neurological symptoms have developed. About the Milwaukee protocol, it says two things. First, it states The protocol is not an effective treatment for rabies and its use is not recommended. and it concludes by saying An intention-to-treat analysis has since found this protocol has a survival rate of about 8% Can someone explain to me how these three statements are logically consistent? The way I see it, if you get symptoms of the rabies, you have two options. One is certain death, one is death in 92% of cases. Now I know option 2 isn't particularly good, but it's better than option 1, right? Isn't "not recommending" the protocol basically saying "just let these people die"? Isn't some result, no matter how marginally good, better than certain death? submitted by /u/5xum [link] [comments]

Why does Turner syndrome have consistent symptoms when the X chromosomes should be redundant? Posted: 13 Nov 2018 02:23 AM PST submitted by /u/TNTiger_ [link] [comments]

Do people with lots of kids have better immune systems due to constantly getting sick? Posted: 12 Nov 2018 09:56 PM PST submitted by /u/nerovox [link] [comments]

Why are parasites considered true living organisms while viruses are not? Posted: 13 Nov 2018 12:30 AM PST Also would there be some parasites that are not considered true living organisms while some are? To me it seems like both a virus and a parasite operate in the same way and going off the definition of what a true living organism is I feel like both of them do not meet all the standards required. submitted by /u/Elitefire001 [link] [comments]

Where did all the water on asteroids come from? Posted: 13 Nov 2018 01:38 AM PST This post on /r/science got me wondering about the origins of water in the universe. The post itself seems to imply that nebulae naturally form water, thus over time creating asteroids loaded with it. But is that the generally held belief of the science community, or is there a more popular theory? submitted by /u/Zermer [link] [comments]

How do fertility/sperm tests work? Posted: 12 Nov 2018 10:05 PM PST Would it be possible to test sperm/fertility at home? submitted by /u/Theprogrammingshow [link] [comments]

Is there a limit on the number of radio telescopes that may be networked together? Posted: 13 Nov 2018 01:28 AM PST I'm just curious because it seems like covering a desert with a million, 1m diameter telescopes would give you the most sensitive radio telescope on the planet. Is there a reason no one has done this yet? submitted by /u/chased_by_bees [link] [comments]

Were there wild pigs or were they breed from domesticated boars? Posted: 13 Nov 2018 01:17 AM PST submitted by /u/just-a_random [link] [comments]

Is Tungsten Carbide an alloy? Posted: 12 Nov 2018 12:25 PM PST I've always thought an alloy is a base metal mixed with another metal(s)/non-metal(s) to change physical properties. I've asked a few people if Tungsten Carbide is considered an alloy. I've got some wild answers: Tungsten Carbide is a metal Tungsten Carbide is not an alloy; it is a compound. Tungsten alloy is a mixture of metals, but not chemically bonded to each other. I'm not an expert with material science. submitted by /u/sqrt69 [link] [comments]

If solar sails are possible, why EM Drive isn't? Posted: 12 Nov 2018 04:42 PM PST Title, pretty much. I mean if all photons have momentum, what is the difference? Edit: as far as I understood, electromagnetic waves from the source (heated wire in bulbs, induction coils) are propagating in EVERY direction, making overall momentum conserved at 0. submitted by /u/LordCrispyCloud [link] [comments]

Is this a reasonable simulation of tension across a hanging rope? Posted: 12 Nov 2018 04:35 PM PST Hi! I was debugging some game physics/kinematics and noticed something I found interesting: the tension across my hanging rope was assuredly not equal across its entirety, which goes against one of the few things I remember from my physics classes a decade ago. However, the simulation seems to match most of the rope characteristics that I can think of having observed in real life (it's actually uncanny; I hate it), so I'm reexamining my understanding of physics. Attached is a screen grab; the red circles represent the tension at each point (the radius of each circle is equal to "tension", which is a variable in the engine with a magnitude and no real units). Is this pattern reasonably representative of what I would expect to see if I were to measure across a real rope with a... tension...ometer? ​ Note: I haven't seen any posts like this, before, so I'm not sure if I'm allowed to do this; I notice that media posts are disabled, but I'm not sure if that means that they're not allowed, or if they're disabled to weed out low-effort spam. I'm assuming the latter (and also assuming that this isn't a low-effort question); please let me know if I'm wrong! ​ submitted by /u/Introsium [link] [comments]

Questions about behavior of electrons in an atom? Posted: 12 Nov 2018 12:27 PM PST Hello I've been learning about Quantum Physics recently, it's super interesting, and it seriously has left me with more questions than answers. Crazy to think that matter is probabilistic on the most fundamental level. I've been thinking about some of the features of the quantum mechanical model of the atom for a little while, and I've tried to combine all questions that I had in my head over the past month into one post. I'd really like to get some intuition on this mind bending topic (full disclosure: contains a lot of questions beginning with "what exactly"). First off, what exactly does it mean for an electron to behave both as a particle and a wave? I know that by calculating the de Broglie wavelength of an electron we get a wavelength that is pretty significant at the atomic scale, but what exactly is the 'wave' that we are referring to here? What exactly is the quantum wave function? Is it a mathematical representation of the probabilities of the electron's position at any given time, or is it referring to the electron as a physical wave in space? What do people mean when referring to an 'electron cloud'? Is it the probability of the position of a single electron, or the electron 'wave' being spread throughout the atom? If it's a physical 'wave', what exactly is it made of, and does it mean that the charge and mass of the electron is distributed across the wave? These are some of the questions I have for now. Just for context, I have a pretty intuitive understanding of Bohr's model of the hydrogen atom, and a basic intuitive understanding of spectroscopy (The photoelectric effect, transition of an electron across energy levels after interacting with a photon of a certain frequency, emission and spectra, etc.). I really don't get the intuition behind electrons treated as 'standing waves'. Thanks for your time! submitted by /u/RyukSkywalker [link] [comments]

How does angiotensin 2 affect GFR? Posted: 12 Nov 2018 06:40 PM PST Im finding the notes in my lecture rather contradictory at the moment and I hope someone can clarify it for me. Note 1: GFR can be regulated by Angiotensin II. When renal blood flow is low, Ang II is released by RAAS pathway and vasoconstrict afferent and efferent renal arterioles decreasing GFR. Note 2: Decrease in BP triggers release of renin which will ultimately produce Ang II through RAAS. This will then lead to increase blood volume due to vasocomstriction of peripheral arterioles-> blood pressure rises, which causes an increase in renal perfusion and therefore an increase in GFR. I understand note 2, as RAAS is stimulated to increase BP through increasing Blood volume. This means that there is more perfusion to kidneys and hence GFR will increase until renin is inhibited. Hence note 1 seems contradictory to me. Please someone clarify!! Thanks in advance submitted by /u/asujinn [link] [comments]

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Didn't the person who wrote world's first compiler have to, well, compile it somehow?Did he compile it at all, and if he did, how did he do that?

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• Didn't the person who wrote world's first compiler have to, well, compile it somehow?Did he compile it at all, and if he did, how did he do that?
• Can the Standard Quantum Limit for the repeated measurement of a free mass be broken in theory?
• How do biologists know when they've discovered a new species?
• Does the recent Vitamin D study published in the NEJM show significant results of reduction in risk of death from cancer?
• What prevents birds from reaching the sizes that pterosaurs did?
• What makes a plastic microwaveable or not?
• Where did the fish in volcanic crater lakes come from?
• How do companies that sell the GFP gene actually purify it nowadays?
• GPS requires microsecond clock accuracy in the satellites but the terrestrial receiver accuracy doesn't matter at all. Why is this?
• What is it about GR that causes the subtle changes in the Perihelion Precession of Mercury?
• If skills are not inheritable then how do cats and other hunters seem to just know how to hunt from a very young age?
• Why is it that people who suffer from a stammer/stutter in their speech mostly are unaffected by it when they sing?
• How do techniques like electric stimulation or vibrating boards actually train a muscle or your body? Or do they even?
• Does reflective radiator foil work?
• How does Bernoulli's principle (basically, saying that pressure and velocity of a fluid are inversely related) work in the case of a tube that enlarges with distance?
• Is the expansion of the universe isotropic?
• Does eating 5 fruit/veg daily actually help you stave off a cold and other diseases?
• Do planets expand when they're closer to the sun? And get smaller when they're distant from the heat?
• What are the recommended controls to be used when making transient transformant plants via agroinfiltration?
• If I inhaled pure oxygen, would I be able to hold my breath longer than if I was just breathing the air around me?
• Are there any anatomical changes in humans living in a poor air quality environment?
• If ulcers are caused by H. pylori, why isn't there a simple test, why are so many much more dangerous diseases misdiagnosed as ulcers?
• Why does the melting point of ice increases under more pressure ?

Didn't the person who wrote world's first compiler have to, well, compile it somehow?Did he compile it at all, and if he did, how did he do that? Posted: 12 Nov 2018 07:26 AM PST submitted by /u/Loldererste [link] [comments]

Can the Standard Quantum Limit for the repeated measurement of a free mass be broken in theory? Posted: 12 Nov 2018 04:10 AM PST Maybe I am cheating here, given that my not knowing the answer may come from my incomplete literature review. But I am getting confused by the claims of the contractive states breaking the limit, and yet a reinterpretation of definitions of precision and resolution seems to validate that repetitive measurements can never be broken due to the Heisenberg Uncertainty Relation between the Standard Deviations of the positions of the free mass at the first and the second measurements, which equals to the SQL. But the review paper I read itself said, after pointing the the HUP=SQL, that the SQL is not a fundamental limit. How? Does the Uncertainty relation mean that the SQL can never be broken? Shouldn't it? Does it mean no one's working on breaking it? All the above paragraph was from papers from before 2000s, so what's the consensus now? submitted by /u/lAPPYc [link] [comments]

How do biologists know when they've discovered a new species? Posted: 11 Nov 2018 06:47 PM PST I am in Ecuador and today I saw a striking hummingbird while hiking around 4300 meters. I didn't know hummingbirds could live that high up, so I did a bit of investigating and found this article about a species discovered only 6 weeks ago and the coloration, size, habitat and range all match perfectly to what I saw. Who knows if I actually saw this hummingbird or a more common species- i could not find any others that resembled my sighting- but that's neither here nor there. It got me thinking: suppose I did see this species, if I had seen it 6 months ago I apparently would've been the first person to ever see it. But at the same time, I would never have known that it was a new species. How do biologists make this determination? Is there a comprehensive list somewhere of every known hummingbird species? Do biologists just go down the list and if they can eliminate every known species then they know they've discovered a new one? How exactly does this sort of thing work? Here is the article in question, by the way- including a picture of the species in question. https://www.sciencenews.org/article/new-species-high-altitude-hummingbird-may-already-be-trouble submitted by /u/BouncingBoognish [link] [comments]

Does the recent Vitamin D study published in the NEJM show significant results of reduction in risk of death from cancer? Posted: 12 Nov 2018 06:18 AM PST The recent study on Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease published in the NEJM didn't show a lower incidence of cancer than placebo. However, it did show a reduction in death from cancer, especially, as noted in the results of the study, when the first two years of the study are excluded. Are these significant results? Is there any additional context/interpretation of these results that could help a layperson make some useful inferences here? submitted by /u/blueberries [link] [comments]

What prevents birds from reaching the sizes that pterosaurs did? Posted: 12 Nov 2018 05:54 AM PST Title more or less. Reading up on how a doubling of bird weight requires 2.25 more muscle power and how wingbeat frequency decreasing as well gives a limit to bird size. Is just the difference in the morphology of the two groups responsible for the size difference? submitted by /u/pacsun1220 [link] [comments]

What makes a plastic microwaveable or not? Posted: 11 Nov 2018 03:47 PM PST submitted by /u/corrado33 [link] [comments]

Where did the fish in volcanic crater lakes come from? Posted: 12 Nov 2018 04:15 AM PST I've seen two volcanic crater lakes in Southeast Asia - Lake Toba and Lake Taal. Both have fish, but both are isolated and cut off from other bodies of water. Since they're volcanic crater lakes wouldn't the eruption would have killed all the fish? So where did the fish in the lakes come from? submitted by /u/thestoryteller69 [link] [comments]

How do companies that sell the GFP gene actually purify it nowadays? Posted: 12 Nov 2018 04:12 AM PST My friend and I were discussing this and read about the origins of discovering GFP - having the cut fluorescent rings off of a million jellyfishes, and squeezing them through gauze doesn't seem like a very efficient process, so we were wondering how companies nowadays would obtain their original sample of GFP. Sorry if it's a silly or basic question, but it's very interresting to think about :) submitted by /u/overcastcat [link] [comments]

GPS requires microsecond clock accuracy in the satellites but the terrestrial receiver accuracy doesn't matter at all. Why is this? Posted: 12 Nov 2018 01:09 AM PST submitted by /u/bushwacker [link] [comments]

What is it about GR that causes the subtle changes in the Perihelion Precession of Mercury? Posted: 12 Nov 2018 04:40 AM PST I create and present Planetarium shows at the local college. I've done show on Special and General Relativity, so I have a solid understanding of these effects, but the mechanism by which GR affects the orbit of nearby celstial bodies still eludes me. What I understand: Mercury's orbit varies ever so slightly from the orbit calculated with Newtonian physics. Apparently this variation is due to relativistic effects since it orbits so closely to the Sun (this is about as far as most internet sources will delve into it). In the last day or two, there are reports that the closely orbiting stars around Sgr A* (the supermassive black hole at the center of the Milky Way) also display variations in *their* orbits which confirm some effect of GR. Are these the same effects, just at different scales? Are their orbits slowing during their closest approach as compared to an external observer? What is it *actually* that's going on that modifies these orbits? Thanks in advance! submitted by /u/Widdy_Boswick [link] [comments]

If skills are not inheritable then how do cats and other hunters seem to just know how to hunt from a very young age? Posted: 12 Nov 2018 05:10 AM PST Im a third year junior cycle student and in science i learned that skills, interest and knowledge are not inheritable, so what makes cats and other hunters get hunting skills? When i asked this to my science teacher she told to just get on with my work and stop asking silly question (shes very petite) so i came here to ask. - learns science in school - has science question - asks reddit submitted by /u/fynical [link] [comments]

Why is it that people who suffer from a stammer/stutter in their speech mostly are unaffected by it when they sing? Posted: 12 Nov 2018 03:30 AM PST (Sorry if I've used the wrong flair.) submitted by /u/Jimmymott [link] [comments]

How do techniques like electric stimulation or vibrating boards actually train a muscle or your body? Or do they even? Posted: 12 Nov 2018 02:31 AM PST I dont know if this does quite fit in here, but couldnt figure a more suitable sub to post this question on. ​ Some Background: I came across such training-techniques several times in my life and recently found out, how big of a business all that get in shape without actually working out stuff has become. I have always been sceptical about that topic, however I have also received such treatment once during physiotherapy, hence a medical procedure based on scientific methods. Also, I have been studying the mechanism of muscle metabolism in a side project of my last job a year ago and I simply cannot figure out, how such a technique is supposed to work. ​ Electric stimulation: I have had some corrective knee-surgery back when I was 14 years old as my right knee suffered from frequent patella-luxations. During regen, I have had frequent physio-appointments which have basically been normal remobilisation techniques, muscle training and - at the end of each session - some electric stimulation with swell current for half an hour. I suppose you all know this kind of thing: Some electrodes stimulate with an electrical current and cause your muscle to flex. The same technique is fundamental to a huge part of teleshopping-articles, who claim to help you gain a Baywatch-Body while sitting on your sofa doing nothing. To my understanding, training is building on activating muscle metabolism, by forcing the processing of carbon-hydrates in an either aerobe, anaerobe lactacid or anaerobe alactacid way, based on what kind of exercise you do (peak-performance, long-time,...) and I actually cannot see electric stimulation to intiate any sort of processing of carbon-hydrates. Hence you will also never produce metabolic byproducts, that activate the second part of muscle-metabolism which relates to breathing. In other words: To my understanding, you have to get out of breath in order to actually use muscle-metabolism. ​ Vibrationboards: I mainly came across that stuff, when I saw some "training"-studios opening up in my town where you can book some workout on such a plate. While this didnt really catch my interest to actually try it, I happened to receive one of these boards now, when my wife actually signed up for some product evaluation on the vibrashaper and we happened to get that thing for free. So long story short, I gave this a few tries and always ended up questioning what the actual benefit of that thing was. If I tried using it the way, that commercials present it, like stand on it daily, get comforatble and let the plate do its magic, and you will end up with your Baywatch-body in a few weeks, the effect was zero. Vibration was definitely not activating my metabolism and no effect was felt after a session. So I tried leveling it up and squated to a degree, similar to the casual pretend to be a downhill ski-racer-exercise. This obviously got my thigs heating up and I started breathing heavily, resulting in an active metabolism. However, comparing that workout to the exact same exercise but without a vibrating board, I actually felt the same. ​ So what do you actually think of such techniques? Am I mistaken for measuring an active muscle-metabolism with whether I heat up and get out of breath? Or are there other aspects, that can actually achieve a training-effect even though you dont feel your body heating up? submitted by /u/v1ech [link] [comments]

Does reflective radiator foil work? Posted: 12 Nov 2018 02:12 AM PST Some hardware stores recommend putting tin foil behind radiators as it 'reflects' or 'bounces' heat back into the room, stopping it from being lost into wall. I'm pretty sure that's nonsense, heat doesn't work like that, otherwise people wouldn't bother insulated walls, they'd just use thin sheets of tin foil everywhere, which is also bonkers. To what extent does science support or disprove the use of reflective radiator foil? Have there been any studies? submitted by /u/illandancient [link] [comments]

How does Bernoulli's principle (basically, saying that pressure and velocity of a fluid are inversely related) work in the case of a tube that enlarges with distance? Posted: 11 Nov 2018 09:10 PM PST College student here, just learning about fluid mechanics, ftp blah blah. So Bernoulli's equation says that pressure + (gravity*density*height) + 1/2(density*velocity squared) is the same throughout a fluid. If we take a fluid flowing through a tube that is horizontal (keeps the same height), we can eliminate the middle term, so pressure + 1/2(density*velocity squared) is constant. I'm just having an intuition problem here. This makes sense when we consider a tube that shrinks in radius; since flow rate Av is constant as well, the velocity is higher as the tube gets narrower. Then, when the tube is larger, the velocity is smaller, but there is more fluid pushing on the walls as the tube shrinks, like the bottleneck effect. This makes sense with Bernoulli's equation - when velocity is lower, pressure is higher, and vice versa. But how does this make sense if the tube widens over time? It just seems like a fluid coming from a narrow opening and losing velocity due to the greater area wouldn't expand enough to make any pressure on the walls of the tube, let alone more pressure than when it was in the narrow part. My professor used the example of a water fountain, or a hose, to illustrate the conservation of Av; as the water sprays out of the end, it slows down and the area expands. But at this point, there's even less pressure on the water than when it was inside the hose! So the pressure and velocity would both be decreasing (and even the height, if it falls). This seems like it doesn't follow Bernoulli's principle. Where am I going wrong here? Thanks! submitted by /u/DeeteetBot [link] [comments]

Is the expansion of the universe isotropic? Posted: 12 Nov 2018 03:40 AM PST Some physical theories, such as string theory, claim that there are more dimensions that the three we are used to. Supposedly, we have a hard time observing those extra dimensions because they are very thin. We know that the universe is expanding when we look at our three familiar dimensions, but i) is this expansion isotropic? ii) Could some dimensions expand while others (namely the extra ones) shrink? iii) Could the universe have a constant volume when taking into account "thin" dimensions? ​ submitted by /u/aheroninthemill [link] [comments]

Does eating 5 fruit/veg daily actually help you stave off a cold and other diseases? Posted: 12 Nov 2018 05:42 AM PST submitted by /u/FesteringCoffee [link] [comments]

Do planets expand when they're closer to the sun? And get smaller when they're distant from the heat? Posted: 12 Nov 2018 01:30 AM PST I was studying phsycs and that I started wandering about this. But there's no information on Google. submitted by /u/MattheVonMartin [link] [comments]

What are the recommended controls to be used when making transient transformant plants via agroinfiltration? Posted: 12 Nov 2018 04:31 AM PST I both want to overexpress and downregulate (VIGS) my gene of interest submitted by /u/f0xgLove_31 [link] [comments]

If I inhaled pure oxygen, would I be able to hold my breath longer than if I was just breathing the air around me? Posted: 11 Nov 2018 09:41 PM PST submitted by /u/DickVanGlorious [link] [comments]

Are there any anatomical changes in humans living in a poor air quality environment? Posted: 12 Nov 2018 03:25 AM PST Do People living in polluted cities develop any anatomical change to adapt to the environment? submitted by /u/spectrumology [link] [comments]

If ulcers are caused by H. pylori, why isn't there a simple test, why are so many much more dangerous diseases misdiagnosed as ulcers? Posted: 11 Nov 2018 03:40 PM PST submitted by /u/TheShiniestOfMen [link] [comments]

Why does the melting point of ice increases under more pressure ? Posted: 12 Nov 2018 05:14 AM PST submitted by /u/iwannaknowwhoami [link] [comments]

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