Please tell me, in a brief paragraph or three, about the Gaia Theory / Hypothesis????
The Gaia hypothesis is an ecological hypothesis that proposes that living and nonliving parts of the earth are viewed as a complex interacting system that can be thought of as a single organism. Named after the Greek earth goddess, this hypothesis postulates that all living things have a regulatory effect on the Earth's environment that promotes life overall. this was a quote from: http://en.wikipedia.org/wiki/Gaia_hypothesis check the link for the full answer Alon
You have to remove one element from earth, without killing all of us what element will you remove?
Right away, I can think of six consecutive elements that could vanish, and for a certain period of time Earth would be slightly less lethal to all of us: polonium, astatine, radon, francium, radium, actiniumAll six are dangerously radioactive. Polonium is acutely toxic. Radon is chemically inert, but usually the next stop on the decay chain is polonium, so nerts to it — nobody will shed a tear over radon’s removal from their basement, will they? Radium, chemically similar to magnesium and calcium, has a tendency to accumulate in the bones and wreak havoc from within as it eventually decays to radon, polonium, perhaps other exotic isotopes, radioactive lead, more exotic isotopes, and finally ordinary lead. Actinium (or rather, atmosphere adjacent to it) gives off a lovely blue glow as a sign that it’s trying to kill you. Astatine and francium just plain don’t like existence; atoms of those are elderly if they reach one day and one hour old, respectively (we don’t even know what they look like, because samples big enough to view would self-vaporize from the radioactive heat)None of these are prevalent enough in the Earth’s composition that suddenly removing them would cause cave-ins, earthquakes, landslides, or the like. Really, I think the worst that would happen is certain antique alarm clocks would stop glowing in the dark, and some minor flaking of pitchblende samples may be observedHowever, since I didn’t get rid of thorium or uranium, all of those elements would eventually return in their present concentrations. Maybe even the glow in your old radium-painted clock, too(A footnote: I didn’t choose plutonium for two reasons. One, there may still be people living on plutonium-powered pacemakers. Two, even though the scope of the question is Earth, I’d certainly be Public Enemy Number One at NASA if I accidentally nuked the power supplies of such spacecraft as Curiosity, New Horizons, and the two Voyagers)
Water: What is the scientific reason for the anomalous expansion of water?
In ice, the hydrogen bonds form a cage-like structure, which is not there in liquid form. That explains why the density of water decreases as a solid, unlike what is expected. Liquid water is densest, essentially 1.00 g/cm³, at 4 °C and becomes less dense as the water molecules begin to form the hexagonal crystals of ice as the freezing point is reached. This is due to hydrogen bonding dominating the intermolecular forces, which results in a packing of molecules less compact in the solid. As you start heating ice, the hydrogen bonds break and the ice melts. All the hydrogen bonds are broken by the time it reaches 4 °C. Hence density is maximum at this point. From here onwards it behaves like a normal liquid, expanding as more heat is applied.For more information, you can also watch the below video.
What are the necessary elements to sustain life on a planet?
Depends on the type of life. For life as we know it, carbon, oxygen, hydrogen and nitrogen are vital, and sometimes sulfur. Other life forms may have adapted and use silicon instead of carbon, or maybe they are metal-based. Until we find evidence for life outside Earth, we will not know for sure.
Is radium essential to life?
Radium is not essential to life and has no modern uses due to its intense radioactivity. Uranium was discovered first, but the study of Radium contributed to the understanding of what radioactivity was. Radium was once used in phosphorescent paint for the hands of clocks. Unfortunately it poisoned many factory workers and was replaced with non-radioactive materials. Radium was once a "health food". In the early 20th century a weak solution of Radium chloride was sold as an American "patent medicine" under the name of "Radiothor". A popular athlete was hired to promote the product but eventually poisoned himself. It was said the contamination was so bad, photographic plates laid on the coffin recorded the images of his bones. The scientist who discovered Radium was also eventually poisoned. M. Curie's notebooks are so badly contaminated they have to be kept in sealed containers. The only impact radium has in the modern world is "Radon proofing". Radium decays into an inert, radioactive gas called Radon. Radium ocurrs in many types of minerals, especially granite. Minute amounts of Radon can accumulate underground and some studies found a correlation between elevated Radon levels in basements and cancer. Hence, a very lucrative industry began. Radioactivity might be essential to life however. Potassium is an electrolyte needed by both plants and animals. However, it has radioactive isotopes. The radiation is mild but might be enough to cause mutations and perhaps this is one of the driving forces in evolution.