h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

thanx 4 your reply, diagrams show distribution of water but my question remains unanswered. Where on this Earth is water created, and how?

"Where on this Earth is water created, and how?"

I think I don't understand the question.

Water (a compound) is "formed" (not really created) by hydrogen and oxygen (elements) combining. According to the Wikipedia article I referenced, the vast majority of this "combining " happened when the planet formed from a gas cloud after the formation of the sun. The elements were created from elementary particles during star formation.

So the vast majority of water on the planet has been here since the beginning of the planet. This water changes form (oceans to clouds/rain to rivers back to oceans), but remains water the whole time.

A very minor amount of water on the planet can be transformed to carbohydrates by plants (photosynthesis):

"Photosynthesis is the conversion of light energy into chemical energy by living organisms. The raw materials are carbon dioxide and water; the energy source is sunlight; and the end-products are oxygen and (energy rich) carbohydrates" (from Wikipedia)

Carbohydrates can be converted back to water via digestion, burning, etc.

I guess my best answer is that *elements* like hydrogen and oxygen were *created* by the formation of stars and planets. Those two elements have combined to form water, and to a large extent that water is what we have on the planet. A very small fraction is changed back and forth from water to hydrogen/oxygen, then back, but generally the planet's water has been here since the planet formed.

So. On this planet, water is "created" only by reforming from oxygen & hydrogen, which came from water in the first place. At least since the planet was formed.

Is your question still unanswered?

Thankyou, my question is answered. I have another question! Is there any other compound that expands when frozen or contracts when heated?

Yes, bismuth (an element, not a compound). You could skate on bismuth, like ice-skating. From Wikipedia:

"Elemental bismuth is one of very few substances of which the liquid phase is denser than its solid phase (water being the best-known example). Because bismuth expands on freezing, it was long an important component of low-melting typesetting alloys, which needed to expand to fill printing molds."

Out of curiosity, is all this leading to something? Are you a terrorist planning to hold the world hostage by some plot involving ... uhhh, I dunno, planting liquid bismuth in, uhhh, microchips, then freezing it? then skating on the whole mess?

If that's it, I'll

no! just interested in stuff that is fun and odd (most people take water for granted and have no idea where it comes from!). Am facinated also by Mercury. Have seen cannon balls floating in a vat of Mercury, awesome! But my first love is water and thanx for helping me out with its cycle, bin asking this question for so long!

Have another question. If the normal body temp is approx 37 degrees, (98) why do we feel so hot and uncomfortable in that climate?

For some reason, your questions fall into my area, chemical engineering. We deal a LOT with heat flow, material flow, etc. In this case, the body is generating heat via metabolism, and that heat has to be dissipated somehow. Heat will only flow from higher to lower temperatures, so the body's heat needs to flow to a lower temperature. So if the body is at 98F, a nice day would be around 70F, allowing the heat to flow away from the body.

Here in Houston, a hot, humid climate, there is another problem. When the weather is hot, the body tries to sweat, allowing the evaporating moisture to carry away some heat. But the atmospheric humidity (water content) gets so high that the sweat does not evaporate. So the body just stays hot ... and sweaty. Happily, we have air conditioning. which is more important for dehumidification than cooling. The drain pipe from my AC runs steadily during the summer. The house stays cool, but more importantly, dry.

In the uk, where I live, our climate has few extremes and moving from 'in to out', there is not a great deal of difference in temp here (like from house to outside, outside to vehicle, vehicle to outside etc) When I visit the USA I have a BIG problem with AC. I find the extreme differences in temp uncomfortable because I am not used to them, from hot to cold, cold to hot. I guess it's what you are used to!
I Think AC is so not right, get aclimatised!
Could you give me some insight into chemical engineering?

Can you give me as much info as possible about Mercury, You know who you are! please?

Just seen the clock, 6 a.m here x

I Think AC is so not right, get aclimatised!

We do try to minimize our use, keeping the thermostat at around 80F vs. many who keep it 10 degrees cooler. And we have had the roof redone with ridge vents so the attic stays cooler. I suspect builders will move toward more natural designs as energy prices go up.

Could you give me some insight into chemical engineering?

Here is a reasonable description:

http://www.collegegrad.com/careers/proft10.shtml

I am retired now, but my job was basically designing chemical plants and refineries for processing hydrocarbons (e.g. crude oil) to intermediate and final products (e.g. gasoline). This involves large steel towers and tanks, miles of piping, complex instruments & computers, etc. Houston is a world center for these kinds of plants:

http://images.google.com/imgres?imgurl=http://www.texasfreeway.com/Houston/photos/225/images/225_deer_park_refinery_D_USE_24-dec-01_hres.jpg&imgrefurl=http://www.texasfreeway.com/Houston/photos/225/225.shtml&h=991&w=2048&sz=334&hl=en&start=15&um=1&tbnid=W-isbBZ0tVtVqM:&tbnh=73&tbnw=150&prev=/images%3Fq%3DHouston%2BRefinery%26svnum%3D10%26um%3D1%26hl%3Den%26sa%3DN

- Steve K.

" ... as much info as possible about Mercury"

I assume you mean the element, rather than the planet or the god. I don't know much about it, other than the basics - a liquid metal at room temperature, used a lot in thermometers, and toxic. I'm sure Wikipedia has a lot more.