Cmac22

In reply to AlphaZNV: Thanks for your input. However, I do not think that some of what you have said is correct. you can think of the body as a system, with the skin as its external barrier, and the liquid you are swimming in as the external environment. The 'scale' does not effect the dynamics in the way you suggest. The pores do not change because the volume of the external liquid is so much larger. Similarly, volume does not make a difference, per say. What matters is the gradients between the internal system (body) and the external environment, across the skin. Thus it is not volume that matters, but the concentration of solutes in the body and external liquid. Diffusion is governed by the same laws in both cases, save for things like active transport etc. inside the body. But in both cases the 'scale' is at the molecular level, i.e. the movement of water molecules and ions from one area to another. However, some of the things you said about different factors and variables made me think, and here is what I have found. The skin consists of 3 main layers. From internal to external: hypodermis, dermis, epidermis. Blood vessels only extend to the top of the dermis layer. Thus, epidermis cells die as they migrate outwards because they have no access to blood vessels. As they die, the cytoplasm (and this water) is removed from the cells and replaced by the protein keratin. The epidermis functions as a 'waterproofing' layer. The epidermis is typically 25-30 cells thick. the outermost layer(s) is called the stratum corneum, and is largely responsible for protection from the environment. It is an effective barrier against most nano sized particles. These cells are also surrounded by various proteins, which add to their adhesive and barrier functionality. 'Trans-epidermal water loss' or 'insensible water loss' is the term use to describe the loss of water to the environment via evaporation. (obviously evaporation is a little bit different, but I think the same principles still apply). The epidermis functions to minimize water loss with a low permeability. However, organisms have little control over 'trans-epidermal water loss' What I take from these things is this: The skin functions to minimize the rate of diffusion/osmosis across it. It does this by blocking the movement of most nano sized particles, and by doing things such as keratinization. as you move to the outward layers of the epidermis, the cells contain less water. These things function to minimize the movement of water. There is little water to move, there is no blood circulation so there is no 'convection', and keratin help absorb/retain water(i think?). Overall though, this does not really answer my question. It only shows that the movement of water through the skin is very slow, ostensibly. However, water does move through it, and defects in skin can cause dehydration issues etc. So how slow is slow? How long would you have to sit in pure water or some very solute heavy solution for effects to become dangerous, if ever?

I was not certain where to post this, sorry if this is not the correct place. During breakfast the other day my friend randomly asked a question somewhere along the lines of "If you were to bathe in a pool of syrup, would you loose water through your skin?" i.e. through diffusion/osmosis. I found I was not able to come up with a satisfactory answer. Ultimately, I decided no, that there must be some barrier to prevent this, but i was not certain at all about this. My thought was, that if this was true, it would also mean that you would swell with water if you were swimming in a lake, which I feel does not happen, although I am not sure about this either. After recently searching google, I still have no answer. The information I found was vague, ambiguous, and sometimes controdictory. Thus, I have turned to the forum to get a satisfactory answer. Is water free to flow through your skin like this? If you sat in syrup (or salt water with a high enough concentation) for long enough, would you become dehydrated? would you die from it? Thanks!

but if mass and energy are similar, that is mass can be converted to energy, then cant energy be converted into mass? hence gravity?

Hey, these questions probably will seem dumb to you but im kinda learning stuff on my own here so help would be nice. i was just trying to understand the whole E=mc^2 equation. i understand its about the energy in atoms and stuff, but does that mean that energy can have mass? what i was really wondering is does energy cause gravity? can light cause gravity? see, dumb questions heh

Thanks a lot Martin. I understand it much better. i appreciate the time you spent to reply and the clarity of your post!

it seems like you have some interesting ideas there. i didnt understand some of it on the first pass but ill look over it again when i got more time. thanks for the input!

i was watching the TV show the universe, the new episode on gravity. in it they show what would happen if you built a hole through earth and put in a kind of transport car that ran off gravity. i think it was assuming like no air resistance or something but they were saying that it would go all the way through and stop on the other side. but the cool part was this. the time it would take to go straight through the earth to the other side is 42 minutes. but also the time to go from one city, to any other city, even if it is not straight through the earth, is 42 minutes! i dunno the conditions for this... like no air resistance and minimum serface resistance.. probably like mag lev or something. so it would take the same amount of time, 42 minutes, to go from seattle to paris, and to go from seattle to new york. i think thats pretty cool! but when i was watching this i had a question. if you are inside the earth while going straight through the center, say 1/2 way to the center, does the fact that you are inside the mass of the earth change anything? by this i mean... well since your passed a lot of earth there is less below you, so even though gravity is stronger because you are closer to center, would it be stronger if you were the same distance away from an object of the same mass with a density that would put you outside of that object? or is the only thing that is importaint is the center of mass or center of gravity? i hope that makes sence heh.

hehe, did thought exist before man!

thanks for the links inow. but yea i dont think a star could get even close to large enough. also i found that the largest know black hole is actualy around 11 billion solar masses. thats big heh... i suppose depending on the size those theorys seem reasonable. i guess the biggest black holes would be from galaxys that merge into several galaxys probably. and the smaller ones possible from just their own galaxy or one more.

i know im a bit late but perhaps it may have been the gamma ray burst afterglow talked about here http://www.astro.ucla.edu/~wright/cosmolog.htm and in more detail here http://www.nasa.gov/home/hqnews/2008/mar/HQ_08086_Swift_Detects_GRB.html im not sure how long the afterglow would remain visible but i believe they can last for days or longer... who knows eh scratch that, i dont think it would be visible for that long

so i was going over the Lineweaver and Davis' Scientific American article Misconceptions about the big bang and there were a few parts i could use help understanding. specifically having to do with the hubble constant. i dont understand how it changes. the article says: "In particular, the constant is proportional to the rate of increase in the distance between two galaxies, divided by that distance." im confused at what this means. in an example, if something beyond the hubble distance sent light towards earth, the hubble constant changes? and so we eventually can see the light? basically how does the constant expand? also later in the article it says: "If light from galaxies receding faster than light is to reach us, the Hubble distance has to increase, but in an accelerating universe, it stops increasing. Distant events may send out light beams aimed in our direction, but this light is trapped beyond the Hubble distance by the acceleration of the expansion." so...now the hubble distance doesnt increase anymore but it used to? one more question from the article: "This reasoning changes if acceleration is not constant, as some cosmologists have speculated. If the acceleration itself increased, it could eventually grow strong enough to tear apart all structures, leading to a “big rip.” But this rip would occur not because of expansion or acceleration per se but because of an accelerating acceleration." is there any newer info about this. is the acceleration accelerating? i remember watchin a show that talked about the big rip as the end of the universe but i dunno how accurate that is comments are always appreciated

well call him up! lets get it goin again

im not quite sure what you are asking here. first... 1000 mass i suppose we can just make that kilograms... but 10,000 (rotations per minute) could mean anything! it depends on the size of the object and the size of the orbit and so on, or axis if u want to rotate it on an axis. and what do u mean gravitational change!? change relative to what? do u mean to simulate gravity inside a spacecraft by rotating it? i think then u would be talking about centrifugal force, which isnt exactly a gravitational change but i suppose would feel similar in this case. or do u mean the gravitational force of the object itself?

Im not sure but i believe gravitational waves have to do with acceleration specifically. if an object is changing speeds or direction, hence exceleration, it will give off gravitational waves...for the most part. this is just from my reading from wiki so i could deffinatly be wrong but i suppose it is worth a look... it seemed to be reasonable http://en.wikipedia.org/wiki/Gravitational_wave But back to the original...or general theme i suppose... so...dark matter doesnt iteract at all with regular matter besides gravitationaly? i mean its hard to say because its unknown what dark matter is i guess. i think that dark matter would fall into black holes more often then it does stars, if its even possible. but for a black hole, or supermasive, that is growing in size, wouldnt it expand to consume the dark matter, rather than the dark matter falling into it? . then again i dont know much about dark matter... but i feel that there is probably a connection between dark matter and black holes.

so i was looking online for info into this question and there wasnt really a whole lot. most of the stuff i found was a bit old and more of speculation. i suppose its mostly speculation anyways but i was curious if there was any newer info about them. how would something millions and sometimes a billion times the mass of the sun come into being? My obviouse guess would be that the occasional planet or star would get to close and get pulled in, along with all the gas around and such. but how often is this? i suppose over millions or billions of years it happens. But the biggest black hole im aware of is about 4 billion times the mass of the sun. that means that in a universe 14 billion years old, if it did form then, it would need to grow by one billion solar masses every 3.5 billion years. that means one new solar mass pulled in every 3.5 years on average. does that seem unlikely or is that possible... i guess it must be but... where does all that mass come from!? i was just reading an article about the milkyways supermassive black hole from 2003 "Only hints of spin have been noted from supermassive black holes, each of which is thought to form and evolve hand-in-hand with the development of the galaxy in which it sits." "depends on the curvature of space around the black hole, which also depends on how fast the black hole is spinning. A spinning black hole drags space around with it and allows atoms to orbit nearer to the black hole than is possible for a non-spinning black hole" http://www.space.com/scienceastronomy/mystery_monday_031124.html this is another one from 2005 talking about its size http://www.space.com/scienceastronomy/051102_black_hole.html one question i have from reading these is does spin effect its gravitational pull. in the second quote there it talks about. how does the spin effect its pull? and what causes this spin? is it the fact that an entire galaxy is spining around it or something else? alot of stuff in there your time and comments are greatly appreciated!