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Monday, July 24, 2017

Is it likely that dinosaurs walked like modern day pigeons, with a back and forth motion of their head?

Is it likely that dinosaurs walked like modern day pigeons, with a back and forth motion of their head?

Is it likely that dinosaurs walked like modern day pigeons, with a back and forth motion of their head?

Posted: 24 Jul 2017 01:13 AM PDT

What would happen if I created a wave motion from lots of small rods going up and down (at subliminal speeds), where the "speed" of the troughs and peaks was faster than the speed of light and then I dropped a small ball in a trough?

Posted: 24 Jul 2017 07:58 AM PDT

As I understand it, it's possible for the peaks and troughs to "move" faster than the speed of light, because it's not really movement, it's just perceived movement, but what then happens if a ball is dropped in a trough and stays in it, being pushed along with the wave motion.

I hope what I'm describing makes sense! It would be a long line of rods moving up and down in sequence to create the wave.

submitted by /u/lindymad
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How did the evolution that produced the Angler fish work, especially the sexual dimorphism?

Posted: 24 Jul 2017 01:30 AM PDT

If evolution is just a series of small mutations, wouldn't males getting smaller and weaker jaws make them less likely to survive? How did the parasitism even evolve? Did a male angler fish suddenly think, okay I'm just going to bite this female, and somehow they fused?

submitted by /u/Crafe
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Lightning equalizes charge between the ground and air - but how does that charge get to be different?

Posted: 24 Jul 2017 12:58 AM PDT

Logistically, how do you move terminally ill patients - particularly across the ocean? e.g. Charlie Gard

Posted: 24 Jul 2017 07:00 AM PDT

Charlie Gard is currently on mechanical ventilation. If the UK High Courts had approved his transportation to the United States, how would that work? What would the costs be?

submitted by /u/send_me_newds
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According to some reports, Arabia was once a "lush green paradise" with monsoon rains. What happened to it?

Posted: 24 Jul 2017 02:01 AM PDT

https://www.google.com.pk/url?sa=t&source=web&rct=j&url=http://www.bbc.com/earth/story/20150223-arabia-was-once-a-lush-paradise&ved=0ahUKEwjy5fLIxKHVAhWD7BQKHUWPCdQQFghkMAs&usg=AFQjCNFveqGomrplW9cUJwV2AEZtyfYtNg

Why is it all sandy and hot now? What happened? I think it is explained in it that Monsoon passes it every 23,000 years? Why is that? Why 23,000 years? What are the factors behind the arrival of the monsoon, the time, and it leaving? If I'm being wrong and there is no monsoon, then can you give me the reasons it's hot and dry now?

submitted by /u/NoorArif
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How is it that different breeds of Canis lupus familiaris (domesticated dog) can develop to be so different in specific individual populations around the world, yet not be subject to speciation?

Posted: 24 Jul 2017 07:29 AM PDT

Distinct breeds exist that vary in size, shape, and other physical qualities greatly, and have evolved that way in specific populations across the globe. Does the way humans selectively bred the species have something to do with it?

submitted by /u/spoofbot
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Is there any UV radiation at night time?

Posted: 23 Jul 2017 03:24 PM PDT

Perhaps from the moon, etc. What about in cloudy nights?

submitted by /u/ranannory
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What shape is the universe? Also what's outside of the universe?

Posted: 23 Jul 2017 02:19 PM PDT

how does the BENDS effect people in submarines? shouldn't the atmospheric pressure within the submarine be controlled?

Posted: 24 Jul 2017 03:12 AM PDT

everyone knows to never go flying the same day you're in the deep sea, but if you're in a submarine, why does it matter? Aren't we able to maintain sea level atmospheric pressure within the submarine no matter how deep we go? if not then how come, because i believe airplanes are pressure controlled so the tech should be there

submitted by /u/CptSnowcone
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Why is the ocean salty?

Posted: 24 Jul 2017 12:43 AM PDT

What machine/process is used to apply a mirror finish to sunglasses?

Posted: 24 Jul 2017 06:21 AM PDT

Is it possible to estimate the amount of biomass that went into the creation of a tank of gas?

Posted: 24 Jul 2017 05:40 AM PDT

I know crude oil came from the accumulated decomposition of plants and animals over millennia. Let's say I had a time machine that could rewind a tank of gas back into the organisms it came from - how much biomass would I have? Like, the equivalent of a few shrubs? A small grove of trees? An entire forest?

submitted by /u/Speckles
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When copying files between hard drives, why does data transfer speed increase exponentially (before reaching the peak)?

Posted: 24 Jul 2017 05:21 AM PDT

Hi. I just copied some video files from my external hard drive to an internal one and noticed how the transfer speed started very low and grew almost perfectly exponentially before reaching and hovering around the max. I took a screenshot: http://imgur.com/a/5lUbV

I was wondering if the transfer speed always grows this neatly and what the reason behind that is.

submitted by /u/NikiHerl
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How's do you mathematically define stability of, for example, a objects orbit?

Posted: 24 Jul 2017 02:40 AM PDT

It can be easy to observe whether or not something is stable, i.e. a pencil being balanced on the end of a finger. But what would constitute a mathematical definition of mechanical stability? Is it situationally dependent?

submitted by /u/Appaulingly
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How do websites/apps keep track of who accesses them? What kind of information does the owner of a website/app get without the user giving it up?

Posted: 24 Jul 2017 01:47 AM PDT

Do they know the IP address of the computer accessing the website? The user's ISP? The user's app store login? I'm just wondering how websites deal with spam/unwanted content.

submitted by /u/Juan-man
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Is it possible to create visible light by the interference of infrared and ultraviolet light? If yes what would we see?

Posted: 23 Jul 2017 03:14 PM PDT

What is a holosystolic murmur?

Posted: 23 Jul 2017 04:02 PM PDT

I understand that systolic murmurs can be midsystolic, early systolic, late systolic, and holosystolic. Since the name doesn't lend much to understand its timing, what is a holosystolic murmur?

submitted by /u/hood_yoda
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What does it physically mean, when a wave function carries an irreducible representation of a crystal lattice?

Posted: 23 Jul 2017 08:26 AM PDT
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Sunday, July 23, 2017

How Does the Equipment in Hospitals/Labs Produce Gamma Rays in the MeV range?

How Does the Equipment in Hospitals/Labs Produce Gamma Rays in the MeV range?

How Does the Equipment in Hospitals/Labs Produce Gamma Rays in the MeV range?

Posted: 23 Jul 2017 07:37 AM PDT

Do they just use radioactive material decays or do they have machines that concentrate/focus them in a way? I know that Cobalt 60 can produce up to 1.3~ MeV during its decay into nickel. I have also seen alpha bombardment of boron using polonium but that only gets up to 3~ MeV. I could not find any information on how higher values are achieved. How are values above let's say 7 MeV reached?

submitted by /u/greatnameforreddit
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What would the world look like if electrons were spinning at 2/5 instead of 1/2?

Posted: 23 Jul 2017 04:43 AM PDT

Why does it seem as though it's more common to get sick when the seasons or weather change?

Posted: 23 Jul 2017 07:03 AM PDT

Is there any herbal medicine that has clinical evidence about its efficacy ?

Posted: 23 Jul 2017 07:10 AM PDT

How effective is water (say, clear pool water) at blocking UV radiation?

Posted: 22 Jul 2017 01:53 PM PDT

I know that light bends as it passes through a different medium, but how does it affect the UV radiation? Can pool water act as a type of sunblock for submerged skin?

submitted by /u/Archerweiss
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Why does a glass full of water, when tapped on a marble tile, make a distinctly different noise as opposed to when empty?

Posted: 23 Jul 2017 07:48 AM PDT

It makes a slightly more deeper noise, as if its hollow. Always intrigued by that.

submitted by /u/Jango214
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Does a warm/hot bath increase or decrease blood pressure? I've read/heard conflicting info.

Posted: 23 Jul 2017 07:42 AM PDT

Why do leaves appear to "turn over" before it rains?

Posted: 23 Jul 2017 07:37 AM PDT

The underside of deciduous leaves are clearly visible before it rains.

I've seen many different speculations as to why, including wives tales, humidity, change in winds, barometric pressure, etc. Is there a concrete explanation?

submitted by /u/JuliettePapaFoxtrot
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On average each generation is taller than the previous, then theoretically we would continue to grow. What would stop our growth?

Posted: 23 Jul 2017 07:16 AM PDT

Who feels the umbilical cord being cut? Mother, child or both?

Posted: 23 Jul 2017 07:08 AM PDT

Why won't honey freeze solid?

Posted: 22 Jul 2017 03:05 PM PDT

Why does log P matter when determining if a drug will work well?

Posted: 23 Jul 2017 05:22 AM PDT

I understand that since there's a lot of different solutions in the body and some are immiscible the drug needs to be soluble in all of them, but why does it matter how MUCH more soluble the drug is in one solution than another?

submitted by /u/smrnnm
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Do animals enjoy music to any extent?

Posted: 22 Jul 2017 10:56 AM PDT

Does it annoy them? Do they like it? Do they even care or notice?

submitted by /u/Theolaa
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How can E=mc^2 have a negative solution?

Posted: 22 Jul 2017 12:45 PM PDT

Paul Dirac showed that there is negative energy but how did he prove this? I don't doubt that it is true, i just don't understand it.

c ist the speed of light squared so it defenitely is positive. For this equation to be true there would have to be negative mass then, right? But negative mass sounds so unintuitive.

Thanks for the help!

submitted by /u/TheRunics
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What is effective field theory?

Posted: 22 Jul 2017 03:34 PM PDT

How did it solve the issue of infinite numbers?

submitted by /u/cedobor
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How did the elements form after the big bang?

Posted: 22 Jul 2017 09:50 AM PDT

If Salmonidae (steelhead, salmon, etc) all return to the same tributary/stream that they were born in, why aren't there thousands of species?

Posted: 22 Jul 2017 09:06 AM PDT

I have always been under the assumption that salmon and related species always return to the same stream they were born in to spawn. If that is the case, why aren't there many more species of them? If my assumptions are correct, wouldn't that create isolated genetic groups which over time would become different species?

Do they crossbreed, sometimes go to other streams, or is this just a common misunderstanding?

Thanks in advance for any explanations you could give.

submitted by /u/CyberSpork
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What is the technical difference between a rectilinear lens and a fish-eye lens and why does one keep the lines straight while the other doesn't?

Posted: 22 Jul 2017 12:53 PM PDT

What is the explanation given for how the contribution of Feynmann diagrams of electron scattering to the total integral depends on the amount of vertices?

Posted: 22 Jul 2017 10:56 AM PDT

[disclaimer, not a physicist] I watched this video on electron scattering, feynmann diagrams, and perturbation theory, in relation to solving infinities with path integrals, and from what I understand the total contribution to the behaviour in electron scattering is a sum of all possible interactions. That's fine and all, just typical Quantum weirdness, but why do 4 vertices interactions contribute with a factor of 100 less?

Basically the question is:

Is it correct that "every additional vertex in an interaction reduces its contribution to the (total) probability by a factor of around a hundred, and why"?

  • What is the physical basis of this, and how generalisable is this to quantum physics?
  • Is generally speaking the relation between total behaviour/integral always a sum of weighted* possible sub-scenarios? Can this weight always be arguably described as some form of complexity?

The reason why I'm asking this is I've always been fascinated and curious about an 'it-from-bit' kind of approach to the foundation of physical reality. I've been exploring quantum computation and quantum gravitation in relation to this, basically just looking for observations that hint to information or computation being more fundamental than matter and energy itself. Apart from the above question, if you have something else interesting I would love to see that as well!

Thank you in advance!

submitted by /u/u_can_AMA
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Saturday, July 22, 2017

Why are reflections (especially in liquid) clearer when viewed at an angle, as opposed to straight-on?

Why are reflections (especially in liquid) clearer when viewed at an angle, as opposed to straight-on?

Why are reflections (especially in liquid) clearer when viewed at an angle, as opposed to straight-on?

Posted: 21 Jul 2017 11:36 AM PDT

Just like in supersonic motion, the object that creates the sound can move faster than the waves it produces, is it possible for the E-field or B-field that make up light to move faster than the light?

Posted: 21 Jul 2017 07:47 AM PDT

What's the implication of the mass of a proton?

Posted: 21 Jul 2017 05:56 AM PDT

According to a recent paper in Physical Review Letters the proton may weight less than we thought.

What are some implications of this difference in how we understand the universe?

submitted by /u/mc8675309
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Two Drones Flying Away From Each Other Along the Equator; Does the Earth's Rotation Affect the Length of Ground Covered By Each Drone?

Posted: 21 Jul 2017 06:11 PM PDT

Sorry if this has been asked before, it's difficult to come up with an appropriate search term.

If two identical drones, hovering a foot off the ground, are placed back-to-back on the earth's equator (parallel with it), and each is then propelled forward along the equator (i.e. directly away from each other) at a fixed speed, would one travel "further" than the other given the direction the earth is rotating? By "further" I mean relative to the surface of the earth, as opposed to a direct ass-to-ass measurement of the drones from their starting point to the end point, which would obviously be the same for each drone.

To keep it simple, let's assume there are no other factors involved (such as variable wind resistance, sunlight/time zones, anti-drone activists with shotguns, that the equator of the earth isn't a perfectly smooth surface, etc.)

This feels like a physics 101 question, but I was educated in science by a rotation of substitute teachers whose actual area of expertise was P.E. or Home Economics, so I'm learning all of this stuff by the seat of my vast adult pants.

Thanks for reading/answering/directing me to previous threads which cover the same question!

submitted by /u/chumlies
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Is it pure coincidence that the rotation rates of Mars and Earth are both 24 hours (-4 & +39 min)?

Posted: 21 Jul 2017 09:07 AM PDT

And maybe this isn't the same question, but: Is there such a thing as non-coincidental rotational resonance between bodies not orbiting each other?

submitted by /u/orbitalengineer
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is there a theoretical limit on the magnification provided by telescopes?

Posted: 21 Jul 2017 06:27 PM PDT

Or, does light have a 'resolution limit' as we try to look at smaller and smaller objects from greater and greater distances?

Suppose we had an absolutely colossal telescope, that magically scaled up to whatever size was necessary to get a good view of the target, whether that was a radius of 1 million miles, 10,000 AU, 5 billion light years, whatever. My first assumption would be that there would be some sort of issue due to the travel time of light when we think on these scales. Ignoring that, is there some point at which no level of magnification could ever be enough due to the constraints of light itself?

If I pointed my magical telescope at the distant galaxy GN-z11 which, according to wikipedia, is 32 billion light years away, is there a level of magnification at which we could observe a single star of that galaxy, or would that be physically impossible due to, say, a lack of photons coming from that source to the telescope?

Is there a hard limit to the transmission of light that bars us from, given this potentially infinitely-sized telescope, seeing specific objects on certain planets at a given distance? Is there any reason aside from limits of construction and resources that keeps us from being able to see a single rock on a planet 80 million light years away? A single cell? A molecule?

submitted by /u/theaveragejoe99
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Why is it easier to cook/warm certain foods in the microwave?

Posted: 22 Jul 2017 04:03 AM PDT

Can extreme tidal forces have an effect on the half life of an atom?

Posted: 22 Jul 2017 07:40 AM PDT

So one of first thing people hear when they are told about black holes, is that they have the power to even rip apart atoms due to extreme tidal forces produced by the gravity. Well I was thinking is this somehow a linear capability. Say we have an Uranium atom orbiting an Earth mass black hole 2cm above the event horizon. Ignoring time diliation, would the Uranium be more likely to give up a helium nucleus (alpha decay) due to the nucleus being pulled apart by the black holes tidal force? Could such a scenario even make an otherwise stable isotope unstable? A Roche limit of sorts, but instead of breaking apart objects held together by gravity, orbiting closer than this limit breaks apart objects held together by the strong force.

submitted by /u/empire314
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How would you calculate the the probability of winning the Monty Hall if you switched and there were 'n' amount of doors?

Posted: 22 Jul 2017 07:29 AM PDT

I've seen explanations of the Monty Hall problem, and they make sense, and I was wondering how you would go about calculating the probability of winning if you

  • Had 'n' doors.
  • Had 1 correct door.
  • Had the number of doors reduced by (n-2) after you made your first choice.
  • Had Switched doors.
submitted by /u/8thPawn
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How big is the universe?

Posted: 21 Jul 2017 05:46 PM PDT

If the universe was created 13.772 billion years ago from a singular point, then why wouldn't the observable universe be exactly 27.554 light years in diameter?

submitted by /u/Iznoe
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Is there a theoretical limit to the field strength of an ideal permanent magnet at room temperature? If so, how would we calculate it?

Posted: 21 Jul 2017 05:57 PM PDT

I've been reading about new powerful iron nitride and manganese-bismuth magnets that are under development, and began to wonder whether there's an upper limit to the strength of a permanent magnet at room temperature and if so how we'd calculate it.

I searched around and found some threads on this topic (like this one on Quora) but no one seemed to attempt to answer the question of what that limit would be.

Some people suggest that an upper limit could be determined by identifying atoms with the highest magnetic dipole moment and find out what the magnetic moment/field strength would be if all of the particles composing it were spinning in the same direction and multiply that by the number of atoms in a solid, but that approach seems to completely omit the fact that the same atoms in different crystal structures produce significantly different macroscopic magnetic effects (like magnetite vs austenite).

Does anyone know if a good answer exists for this question or it's incalculable for some reason?

submitted by /u/squakmix
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How do dielectric boots work?

Posted: 21 Jul 2017 06:09 PM PDT

When inflating a balloon using your lungs, are you effectively filling it with Carbon Dioxide and will this affect it in comparison to inflating it via a compressor?

Posted: 21 Jul 2017 03:09 PM PDT

Is there an upper bound to how long an electromagnetic wave can be?

Posted: 22 Jul 2017 12:41 AM PDT

If light is a result of changing electric and magnetic field, can I create visible light by using just an A.C source and a wire?

Posted: 22 Jul 2017 12:21 AM PDT

By varying the direction of current I can set up a changing electric field which will in turn will create a changing magnetic field and hence should produce EM waves, right?

submitted by /u/iOfTheApple
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Why do some antibiotics make it so one cannot go into the sun?

Posted: 21 Jul 2017 11:07 AM PDT

How do non-contact voltage detectors work without any current running through the wire?

Posted: 21 Jul 2017 11:33 PM PDT

I was using my non contact voltage detector and it seemed to be working even without any current running through the wire, I googled to confirm and I was correct, so how does this work?

submitted by /u/captainboggle100
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How can strong gravitational lensing create multiple images, especially four images?

Posted: 21 Jul 2017 11:08 PM PDT

I've read several articles including wikipedia about strong gravitational lensing. They all explain in detail with animations how Einstein rings can appear, and then go on to mention the possibility of multiple clean images as a matter of fact, no explanation given. The animation on wikipedia somewhat pictures how double images appear before and after the Einsteing Ring due to a transition - but how can four rather crispy images appear?

submitted by /u/andreasbeer1981
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Simplest proof that |R^2| = |R|?

Posted: 21 Jul 2017 11:34 AM PDT

Just watched this video on Hilbert space-filling curves. I realized that the existence of a bijection from R to R2 like the Hilbert curves in the video is effectively a proof that the cardinality of R and R2 are the same, but what is the simplest proof? Is it a matter of finding the simplest space-filling curve?

submitted by /u/graciousgroob
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What is the shape of space?

Posted: 21 Jul 2017 06:39 AM PDT

Does space have a geometrical form? And if so what form? Flat? Hyberbolic? Squared?

submitted by /u/LeFrosch
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What makes a beach?

Posted: 21 Jul 2017 05:09 AM PDT

I'm currently on holiday in Sydney (marvellous city. Shame about the 24 hour commute to get here) and around Sydney harbour are many, many beaches; some big (Bondi), some small (the 3' wide example near Jeffrey St. Wharf).

Through my incredibly limited knowledge of geology, I'd assume it would be something to do with erosion of the sandstone, and something to do with tides in deciding (for lack of a better word) where beaches form, but Bondi is in a cove, so why has only some of that cove turned to beach and the rest remained as a sandstone cliff?

Basically, what forces act on one area of coastline to form a beach, and not others?

submitted by /u/TheReverend210
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