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Monday, October 3, 2016

Why do sponges get hard when dry but only after use with water?

Why do sponges get hard when dry but only after use with water?

Why do sponges get hard when dry but only after use with water?

Posted: 02 Oct 2016 07:38 AM PDT

When you buy a new package of sponges, they are dry, but they are soft. When you use a sponge, they are wet and soft. After that first use however, they will dry out and harden. What exactly is happening with that? Are the sponges treated with something that keeps them soft before the first use?

submitted by /u/triangle60
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What makes plastic so cheap and easy to produce as opposed to any other material?

Posted: 02 Oct 2016 04:06 PM PDT

Why does the denaturation of longer DNA helices show more cooperativity than the denaturation of short strands?

Posted: 02 Oct 2016 08:56 PM PDT

Is it not possible to do a one to one mapping between the values of 0 to 1, with the value of 1 to infinity?

Posted: 02 Oct 2016 11:58 PM PDT

I am having a really difficult time understanding the concepts of different sizes(types?) of infinities. If it is possible to do this mapping, how does this not contradict the different sizes of infinity. If I understand it correctly the values from 0 to 1 are bounded(capped) at 1, but as long as there are infinitely many of those values, how could you not do a 1 to 1 pairing with each value of 1 to infinity, what am I not understanding?

submitted by /u/qna1
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Do your ears pop when skydiving? Or, why don't skydivers see physical effects of rapid pressure change the way divers can?

Posted: 02 Oct 2016 05:18 PM PDT

Will the methods behind future cures/treatments of HIV be applicable to other long term viruses?

Posted: 02 Oct 2016 11:38 AM PDT

A post about a new treatment for HIV made the front page. All the headlines I read for new HIV treatments seem to be fairly targeted at just HIV. Is there a way that this new treatment or any other experimental treatments could be applied to, say HSV or HPV? Or will specific cures for those viruses need to be developed separately?

submitted by /u/h00rayforstuff
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Do electrons have parallel spin in the anti bonding orbital?

Posted: 02 Oct 2016 09:54 AM PDT

My semiconductor devices textbook mentions that electrons in the anti bonding orbital must have parallel spin because the spatial part of the wavefunction is asymmetric to electron swapping. Is this true, and if so can I get a mathematical explanation?

Thanks,

Fenix

submitted by /u/fenixfunkXMD5a
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If a decimal number is constructed as {0 . D1 D2 D3 ...} where Di = Random(0..9), for i = 1 to ∞, does such a number "exist" in the Real Numbers? Or in other words, do completely random numbers exist in the Reals?

Posted: 02 Oct 2016 07:42 AM PDT

Is it possible to find an effective infinity for all intents and purposes?

Posted: 02 Oct 2016 09:20 AM PDT

I was in the shower the other day and wondered if you could find a number (an astronomically big number) that for all intents and purposes might as well be infinity in our universe. I understand infinity as a concept but if we assume the expanding universe will eventually stop expanding and shrink (due to gravity overcoming), then aren't there a maximum number of "things" that could possibly happen in our universe from time 0 to the end of the universe? Wouldn't the maximum number of things possible be an actual defined infinity as as it would be impossible to do anything more than that? Therefore calculating past it would be purely abstract or theoretical since nothing could happen more than that effective infinity amount of times? I hope I'm making sense. This is a [WARNING] personal theory that I have worked on a bit and wrote it all down in a pseudo-proof/explanation you can find here. I'd like to see if what I'm saying is correct and/or if it has been explained before. I'm not a mathematician or physicist or anything, just a college freshman with an interest in these kinds of questions. Thanks.

submitted by /u/Slim_Pickens_
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What is the use of a Van de Graaf Generator ?

Posted: 01 Oct 2016 11:23 PM PDT

I just read about it in school. I think i understand is basic working and I know it is used to build up high voltages. But why do we need millions of volts ?

submitted by /u/Great_Scott21
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How does polarization work in terms of electric and magnetic fields?

Posted: 01 Oct 2016 11:00 PM PDT
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Sunday, October 2, 2016

When light is redshifted, is it losing energy? When it's blueshifted, is it gaining energy?

When light is redshifted, is it losing energy? When it's blueshifted, is it gaining energy?

When light is redshifted, is it losing energy? When it's blueshifted, is it gaining energy?

Posted: 01 Oct 2016 07:12 AM PDT

And if so, how exactly? And how does this work in terms of relativity and the position of the observer?

submitted by /u/escherichia
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How does intelligence change with age?

Posted: 02 Oct 2016 12:44 AM PDT

Feel free to answer this question from any academic angle you feel is appropriate. Also, please link or cite any research articles if you are referencing them.

submitted by /u/Dzianger
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Are there any bodies in space with temperature below temperature of cosmic microwave background of ~2.7 K?

Posted: 01 Oct 2016 11:15 AM PDT

As far as I understand every body put in space would eventually reach temperature of about 2.7 K due to the CMB1. So is there any possibility of covering bodies/bending waves or anything that would be able to produce a body with stable (in terms of that it would not eventually reach 2.7 K back) temperature below that?

Additionally, are we as a people able to create such a circumstances that would create desired conditions? Would just perfect2 vacuum and some kind of cover be enough?

1 Cosmic Microwave Background

2 I'm aware we can't create perfect vacuum, let's just say the best that we are able to create.

English is my L2, don't hesitate to correct any errors.

submitted by /u/Rotifyld
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In terms of anatomy, why are some voices husky and some smooth?

Posted: 01 Oct 2016 10:49 PM PDT

Does gallium dissolve gold?

Posted: 01 Oct 2016 01:33 PM PDT

I'm looking to use gallium as the liquid phase in an electronics cooling setup.

If I were to make the cooling block and the radiator out of gold plated silver, would the gallium phase dissolve the gold plating or otherwise destructively interact with the gold/silver solid?

submitted by /u/thecureforstupid
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Are the genes for eye color linked to the genes for eyesight? In other words, if my child inherits my eye color will he inherit my good eyesight?

Posted: 01 Oct 2016 02:55 PM PDT

Could mercury be used as a hydraulic fluid?

Posted: 02 Oct 2016 12:18 AM PDT

With its weight and density it seems like it could be a very powerful fluid. I'm sure a major factor would be the toxicity of the amount of mercury used, but is it possible?

submitted by /u/jake831
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How are "scans" Of renaissance art made since flash photography can damage paintings?

Posted: 01 Oct 2016 01:39 PM PDT

If I was walking from West coast to East coast on North America right as the Cretaceous period was at its prime, how would the diversity of ecosystems and species compare to that same walk today?

Posted: 01 Oct 2016 11:36 AM PDT

What pressure is necessary for helium to be dissolved into a liquid? (such as beer)

Posted: 01 Oct 2016 01:04 PM PDT

I don't just mean the pressure force required to dissolve the helium into the liquid, but also the pressure outside the vessel that would be required to keep the dissolved gas from escaping to quickly to be drank. I also would like to know if the pressure that is on the outside of the vessel would be a suitable environment for a person.

submitted by /u/thepaulsack
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Is time dialation observed in particle accelerators?

Posted: 01 Oct 2016 12:39 PM PDT

A particle with mass accelerated to near the speed of light should experience substantial time dialation. Accelerated enough, to us it could even be considered to be nearly standing still to a relative observer because it's time reference is so slow. But in researching this, I don't find any information on this effect.

So my question is; as particles are accelerated, do we observe them starting to move slower through the ring from our reference as they near their references speed of light?

submitted by /u/pcx99
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What makes one bus protocol faster than another? (e.g. UART vs USB)

Posted: 01 Oct 2016 11:37 AM PDT

I'd always thought that it just the number of pins so that more data could be transferred in parallel. But, looking at USB's pin outs there are only 2 data pins while being vastly faster than UART. Is it just clock rates? If so, what prevents me from running UART at a 1 Mbps baud rate?

submitted by /u/SnowdensOfYesteryear
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What geologic factors determine whether decayed carbon will end up as natural gas, oil or coal?

Posted: 01 Oct 2016 01:40 PM PDT

Certain organisms, like tadpole shrimps, not only are hermaphrodite but can also auto-impregnate. Is the offspring of this kind of reproduction a clone of its parent? What are its advantages/disadvantages?

Posted: 01 Oct 2016 09:15 AM PDT

I discovered this fact through this article and I can't find much information about it.

Apparently this is a trait of only certain kind of hermaphrodite organisms (e.g. snails are hermaphrodite but need another individual to copulate).

submitted by /u/javierbg
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At what Age do children recognize themselves as a person? When and how do they become selfaware?

Posted: 01 Oct 2016 01:20 PM PDT

I've heard mitochondria produce water... so could we survive on nothing but dehydrated food?

Posted: 01 Oct 2016 03:21 PM PDT

Is there a possibility of creating a solid block with very dense matter, such as Ununoctium?

Posted: 01 Oct 2016 03:03 PM PDT

This is what I want to know: with current technology, is there a possibility of creating a block/cube/anything solid with Ununoctium? The reason I'm asking: I'm curious about the heaviest (synthesized) element known that can exist on earth. I hoped ununoctium would be a good option, but if not, what is? For example, one can pick up Osmium and throw it, even though it's very heavy. Is there anything man-made and heavier that is solid and can be picked up (in theory, and indirectly if needed)?

submitted by /u/Awesomedispantsable
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Do liquid-based foams have the same fluid dynamics (viscosity etc) as their parent liquids?

Posted: 01 Oct 2016 02:52 PM PDT

Could the distribution of cosmic background radiation be uniform if we assume the larger universe is oddly shaped?

Posted: 01 Oct 2016 01:32 PM PDT

Meaning that where we measure higher levels of radiation it could be because of a "dent" in the shape of the (non-observable) universe? In other words, could there be a shape of the total universe thinkable where radiation was distributed evenly, but would still yield our current maps, seen from a point somewhere from within that distribution? And, somewhat related, why do we seem to prefer the Mollweide projection for maps of cosmic background radiation?

submitted by /u/waal70
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Is there any rhyme or reason to the charges of polyatomic ions, or is it completely random?

Posted: 01 Oct 2016 09:32 AM PDT

The charges never seem to line up with the elements that each polyatomic ion contains. (ex. Nitrate's charge is -1, but contains 4 negatively charged atoms, so shouldn't the charge be at least -4? Peroxide's charge is -2, but contains 2 oxygen, so shouldn't the charge be -4?)

submitted by /u/TheDesertSnowman
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Saturday, October 1, 2016

Is there an element/compound that is denser as a gas than it is as a solid?

Is there an element/compound that is denser as a gas than it is as a solid?

Is there an element/compound that is denser as a gas than it is as a solid?

Posted: 30 Sep 2016 08:29 PM PDT

If plant life existed on mars in the past, would there still be coal/oil under the surface today?

Posted: 30 Sep 2016 07:03 PM PDT

Since the QT interval represents the depolarization AND repolarization of the ventricles, is it linearly correlated with heart rate?

Posted: 30 Sep 2016 07:43 PM PDT

Are there numbers outside of C? If so, is there an ensemble including every other number ensemble we know?

Posted: 01 Oct 2016 01:32 AM PDT

Just started learning about complex numbers in math class in high school, and asked my teacher if C included all the numbers we know, and she told me it doesn't, but she can't really tell me more about it. I asked the same question to my brother who's in studying math in university, and he told me the same thing. So, what are the non-complex number ensembles, and is there a number ensemble that includes all the complex and non-complex numbers?

submitted by /u/MrEvilNES
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Could roadways contribute to rising global temperature, to a significant degree?

Posted: 30 Sep 2016 01:12 PM PDT

I've heard the theory that enough solar energy hits United States roadways to power all of the America's energy needs.

To me it seems this black surface area absorbs a tremendous amount of heat energy. Whereas it would otherwise be converted to chemical energy (plants), reflected back to space (snow), or halfway reflected (dirt, other).

While certainly not the largest contributor, can this be a factor for rising global temperature?

submitted by /u/MuphynManOG
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What makes a nuclear reaction a direct reaction or a compound reaction (non-resonant vs resonant)?

Posted: 30 Sep 2016 07:33 PM PDT

According to this website, nuclear reactions can be classified as direct or compound. I understand the distinction between the two, but what causes a given reaction to direct/compound? Can the reaction's type be predicted without performing the reaction?

submitted by /u/onlyhtml
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If dirt on Earth is called "earth", what is dirt on Mars called?

Posted: 30 Sep 2016 11:49 AM PDT

If movement is relative, and F=ma, does that mean that force is also relative?

Posted: 30 Sep 2016 05:42 PM PDT

Are we able to see black holes? If so, can we see the Milky Way's black hole (from earth/telescope)?

Posted: 30 Sep 2016 05:45 PM PDT

What's happening on a molecular level that makes pasta so sticky?

Posted: 30 Sep 2016 04:39 PM PDT

If I were placed into a hollow sphere with super-massive walls, would I experience time dilation but not gravity?

Posted: 30 Sep 2016 05:27 PM PDT

Can you tell if two chemicals will react just by their names?

Posted: 30 Sep 2016 05:15 PM PDT

Im curious if there is a general method in determining whether a chemical compound is compatible or not with another simply through means of their names. For example would all silicones melt in all esters? Would different esters be compatible simply because they are both esters? Would fluorosilicone be affected by silicone based fluids? Etc Etc. Please explain simply, only have basic chemical knowledge. Thanks

submitted by /u/chem689
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Why do Galaxies look like spirals?

Posted: 30 Sep 2016 07:50 AM PDT

I'm pretty sure that it actually spirals because the center is rotating faster due to being closer to the core, so its a spiral as opposed to more of a star. But I'm not ever sure if that's true.

My main question is why do they get that sort of shape in the first part, shouldn't the settle as more of a disk? What causes the arms to form?

submitted by /u/PM_me_your_spacegoat
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Are there any ecosystems relatively immune to global warming?

Posted: 30 Sep 2016 11:12 AM PDT

Why does matter accreting onto a white dwarf cause it to go nova, and not just "reignite" into a regular star again?

Posted: 30 Sep 2016 07:01 PM PDT

For those that can lipread, is it possible to distinguish regional or international accents by using solely lipreading?

Posted: 30 Sep 2016 09:56 AM PDT

Do metals/alloys resonate electrically like quartz and other crystals do?

Posted: 30 Sep 2016 12:05 PM PDT

I know that quartz crystals can be made to oscillate electrically, and for this reason are used as high-Q filters for the feedback paths of electrical oscillators. Is there a similar resonant property for metals (obviously not piezoelectric)? I know that the quartz resonant frequency is influenced by its dimensions, so I'd be looking for something more intrinsic to the metallic structure itself (independent of overall geometry). For instance, if I am presented with a sample claimed to be 70% gold, with the remainder being copper, is there any way to test that electrically? Something like "The impedance of such an alloy would have a peak/trough at 770MHz. The actual peak was measured at 760MHz, indicating only 60% gold."

submitted by /u/averazul
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How do we know that young earth was hot and molten?

Posted: 30 Sep 2016 11:44 AM PDT

The Rosetta mission provided a lot of evidence about how the young solar system formed, including the aggregation of dust particles to produce larger objects. They also discussed the source of earth's water. Some research suggests it must be extra-terrestrial since the young earth was hot and molten and water would have boiled off. But I can't find what the evidence is for a hot molten young earth (except perhaps after the proto-moon collision). How do we know the earth didn't simply form by the cold accretion of particles from the nebula, eventually heating the core, but not the surface? Related, if everything formed from the planetary nebula, why is the H-D ratio different in different objects?

submitted by /u/stickylava
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Do the lack of BSL-3 facilities worldwide increase the risk of a worldwide epidemic? Why exactly do we not have more of these facilities?

Posted: 30 Sep 2016 07:48 AM PDT

As the titles states.

submitted by /u/perkam
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