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?
What makes plastic so cheap and easy to produce as opposed to any other material?
Why does the denaturation of longer DNA helices show more cooperativity than the denaturation of short strands?
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?
Do your ears pop when skydiving? Or, why don't skydivers see physical effects of rapid pressure change the way divers can?
Will the methods behind future cures/treatments of HIV be applicable to other long term viruses?
Do electrons have parallel spin in the anti bonding orbital?
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?
Is it possible to find an effective infinity for all intents and purposes?
What is the use of a Van de Graaf Generator ?
How does polarization work in terms of electric and magnetic fields?

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
[link] [comments]

What makes plastic so cheap and easy to produce as opposed to any other material?

Posted: 02 Oct 2016 04:06 PM PDT

submitted by /u/KingChronos
[link] [comments]

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

submitted by /u/CrispusAtaxia
[link] [comments]

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
[link] [comments]

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

submitted by /u/on_island_time
[link] [comments]

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
[link] [comments]

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
[link] [comments]

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

submitted by /u/LongtimeLearner99
[link] [comments]

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_
[link] [comments]

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
[link] [comments]

How does polarization work in terms of electric and magnetic fields?

Posted: 01 Oct 2016 11:00 PM PDT

submitted by /u/shadowz749
[link] [comments]