Leader Bee

What about a mass driver on the moon, with a capsule similar to the landing modules used by astronaughts to land it safely on Earth? As for getting it up there, thats harder - but once you have the materials you can mine the rest from the surface?

I've read that Francium is so rare that no more than 30g Exists on earth at any one time. What makes Francium exist in much lesser quantities than some of the other alkali metals?

If limiting the harm was to make certain results unobtainable ( say we were testing a new drug for soldiers that inhibits pain / increases pain tolerances & endurance ) then how do we measure those results if pain and suffering are sidestepped? I imagine the majority of responses to this thread will be of the "it's simply unethical" party, what if someone simply volunteered simply for the good of mankind (however stupid that might be) to test these drugs and be subject to being shot, beaten, frozen, burned... Would it make it ethical if it was the subjects choice out of their own free will?

Yes, bleach tends to have a lot of chlorine in it. What about alcohol & liquid chlorine?

So if someone is on death row they should be given an option of lethal injection or "benefit to humanity via the means of vivisection"? As long as they sign a consent form there should be no legal troubles from any i'll effects sustained afterwards. I don't see why there should be any trouble if there are complications that arise from any experiments as the experiment is there to discover an outcome anyway... We wouldn't know what to expect until we have the result.

During the war years there were several experiments involving the inmates at Auschwitz, ranging from experiments on twins, toxic gas exposure and hypothermia. While it's quite clear that this is unethical due to the inmates being innocent of any crimes it's also undeniable that these experiments were of value - Most of modern medicines understanding of the effects of and how to treat hypothermia came directly from these experiments. What are peoples views on the experiments conducted there? Would it be anymore acceptable to people if instead of innocent and unwilling captives if people convicted of crimes / sentenced to capital punishment were automatically selected for live experimentation instead of just wasting a resource by leathal injection - human experimentation clearly has it's value and this seems the most legitimate way we could justify it.

Number 6 doesn't really hold for stars; the requirement is a response to stimuli - If i push a rock it will move but it isn't really proactively responding to me touching it, though it is being influenced by me exerting a force on it. Same with a star, it doesn't choose to move but follows the laws of physics which as you say it is influenced by, but certainly not responding to. A virus I would assume does fit the requirements to some degree, but my knowledge of this area isn't really good enough to say so. The requirements say that to classify as life that most points must be met, not all. These are only guidelines however as there is no 100% definition of life. Would a sufficiently intelligent computer that could pass the turing test be classified as life?

Taken from a thread debating the definition of life (Search Transhumanism: Man vs Machine) Choose a selection of the above that apply to the sun and explain your reasoning for the answers. I find it unlikley that these will apply to a star, though some might with a bit of imagination.

Similar to how a car would die once your fuel tank is empty. Doesn't mean it was necessarily alive to begin with. A cars engine also needs to "breathe" for combustion to occur but there are more requirements that what I stated previously to be considered alive.

How'd you figure that? They don't reproduce, breathe or grow.

Everybody has asked the question of what would happen if you were to drill a hole directly through the centre of the Earth and I find the answers fascinating, if not plausible. But this isn't about a hole directly through the centre of the Earth. I'm curious to know what the effects of a long tunnel from maybe one side of a contenent to another (lets say Russia as that covers a large portion of Earths landmass) I know that an in antipodal tunnel it's likely that you'd experience weightlessness but how would one perceive a perfectly straigth tunnel that didn't intersect Earths core? I beleive that even though the tunnel would be straight one would experience it as a U shaped tunnel going downhil at first, until the centre of gravity is reached whereupon it would appear or feel to rise again into an uphill slope. with it being a straight tunnel i'm curious of this U shaped phenomenon and wonder if anyone else has had any thoughts on the subject?

http://www.howstuffworks.com has always been interesting to me. It gives an in depth analysis of hundreds of subjects and is probably the second best site I've ever seen for answering all those "how does that work?" questions you have in life ( second to asking the resident experts here at SFN that is!)

You mean something a bit like one of these? http://en.wikipedia.org/wiki/Mass_driver Also from wikipedia: [edit] Spacecraft-based mass drivers A spacecraft could carry a mass driver as its primary engine. With a suitable source of electrical power (probably a nuclear reactor) the spaceship could then use the mass driver to accelerate pieces of matter of almost any sort, boosting itself in the opposite direction. At the smallest scale of reaction mass, this type of drive is called an ion drive. No theoretical limit is known for the size, acceleration or muzzle energy of linear motors. However, at higher muzzle velocities, energetic efficiency is inevitably very poor. While linear motors can, with current technology, convert up to about 50% of the electrical energy into kinetic energy of the projectile, the energy of interest is the kinetic energy of the vehicle, and as the muzzle velocity increases, this is a smaller and smaller percentage of the generated power.[citation needed] Since kinetic energy of the projectile is ½mv², the energy requirements vary with the square of the specific impulse, so in a design one must choose a tradeoff between energy consumption and consumption of reaction mass. In addition, since momentum of a particle of mass m has momentum mv- proportional to velocity, but energy is a square law, so the average thrust for a given energy is inversely proportional to the velocity of the particles. In other words, heavier projectile masses give lower specific impulse but proportionately higher thrust. (See propulsive efficiency for more details).[citation needed] Since a mass driver could use any type of mass for reaction mass to move the spacecraft, this, or some variation, seems ideal for deep-space vehicles that scavenge reaction mass from found resources. One possible drawback of the mass driver is that it has the potential to send solid reaction mass travelling at dangerously high relative speeds into useful orbits and traffic lanes. To overcome this problem, most schemes plan to throw finely-divided dust. Alternately, liquid oxygen could be used as reaction mass, which upon release would boil down to its molecular state. Propelling the reaction mass to solar escape velocity is another way to ensure that it will not remain a hazard. Space is almost completely empty, so propellant sources are only to be found at asteroids, comets, moons and planets.

By that logic does it mean that Earth will not continue in its orbit and will eventually fall into the sun? (provided we assume the sun will remain a main sequence star and not expand)

How do we make interstellar travel possible? Can we create a time travel device? Can we bring the dinosaurs back to life? Along with many many other questions, scientists have all sorts of things they have yet to discover and perfect. "Perfect" being the important word here as scientific discoveries are rarely eureka moments where you have nothing then suddenly you have all the answers, research is incrimental. Basically, answering questions about how the universe works just isn't easy and if you don't hear of any groundbreaking developments for some time it isn't because there are none left to answer, it's more likely that they're too busy running experiments & researching the subject so they can produce one.

I believe i've seen a documentary on this before, the designer had plans for it to supply oxygen to a marine lab somewhere on the coast. I've found a link to this companies website explaining the technology: http://likeafish.biz/

OK it's a dumb question... because they have gills! But aren't those gills just extracting oxygen from the water already? I would have personally thought that even though water may be more oxygen rich (being hydrogen and 2 oxygen atoms after all) that air would have been easier to extract the oxygen from as it's already freely floating around and therfore no need to seperate the 02 from something I'm no biology expert so I thought i'd better ask this burning question on SFN before I forgot I was curious about it.

I'm sure breathing pure oxygen, at least for extended periods of time is actualy bad for you...

Quick and simple: Is the hubble constant the rate at which galaxies are moving away from us or the rate of "cosmic expansion" and the speed at which the distance of space increases between us?

How can an object move at a speed less than nothing?

I believe they should be told for medical reasons. Yes there is an argument for moral reasons where they would have the possibility of feeling ostricised from the family but to me this is insignificant if the family treats them no differently. If the adopted were to fall ill, and say requires a bone marrow transplant or similar then the likelyhood of a family member being a donor is incredibly slim and they'd likley find out then. Better to tell them at a young age so that if anything does crop up they will know where they stand.

I play a lot of online games and I generally tend to need to select a unique name. I thought this one sounded quite cool and is ALWAYS available. Now I use this name everywhere for consistency reasons.

Yes, with no knowledge of what is going on outside it would appear as though the gun has a standard muzzle velocity WRT the trains occupants; If there was another reference frame where people outside the train could see inside the muzzle velocity would be Muzzle velocity + Train speed. Merged post follows: Consecutive posts merged No, this is incorrect because the bullet is still moving, as with our elevator and football scenario, relative to the stationary gun up until the point it is fired ( not being a physics bod it probably still is moving relative to the gun once fired but I cant explain the reason ) therefore the inertia of the bullet(correct?) is moving towards the shooter and this would appear to have a negative effect in velocity on the projectile with respect to the person firing the bullet -- I think.

My understanding is that because they share the same (Or very similar) reference frame they act just as they would in any other situation.

Isn't this thought experiment similar to the one where you fire a bullet inside a perfectly stable train with no windows or knowledge of the outside world it will move just as fast as you would expect when firing it in a normal situation on the ground rather than expecting it to travel at the bullets muzzle velocity plus the speed of the train?