Xyph

I always wonder about the philosophical implications of immortality whenever it's brought up... How death is a part of life, is required to maintain innovation and change, is a necessary part of the cycle of existence, etc, etc, etc... But then I realise that despite all this, I really would, in fact, like to live forever. Yeah, so maybe I would get bored eventually - but I'd far rather let an increasing boredom with all that existence has to offer be the cue for my demise than the increasing inefficiency of my cellular replication. Oh, but that said, I do feel immortality should be a privelege rather than a right. I realise such a system would have a huge amount of potential problems, but I'd still rather be one of a few deserving immortals (although I realise this would subjective to an extent) amongst masses of useless-but-rich immortals, than a mortal unwilling to involve myself in such an abused system.

I agree that sapience is probably a very rare phenomenon. Multicellular life is probably quite rare, but likely far more common than the level of sapience that humans have evolved. I'm not sure exactly how rare, but likely rare enough for any civilizations at a similar level of development to our own to be significantly outside the range of current SETI searches. That said, although I expect we'll find (possible quite a few) other complex planetary ecospheres before we find any hint of other intelligent life, its probably still only a matter of time (even if more time than commonly supposed) before we do run into creatures that are obviously sapient. Even if sapience is a very rare evolutionary result, the rarity is probably balanced somewhat by the fact that it only really needs to evolve once on any single world - once it has evolved, it almost guarantees it's own survival, far more than any other evolutionarily aquired traits. While wings, eyes, and pretty much all other limbs and organs (which, at least as far as we can tell from our own world, often evolve multiple times) can wither and become vestigial as organisms use them less, I think it's fairly apparent that it would be very, very difficult, barring some sort of planetary catastrophe, for a sapient species to evolutionarily lose their sapience.

On the base-element part of your question, Silicon (or Silicon-Oxygen) or Phosphorus-Nitrogen bases are the most commonly proposed alternatives to carbon for life elsewhere in the universe, as far as I know. Both, however, suffer from a far lower cosmic abundance than carbon, the latter especially. Beyond that, I don't know nearly enough to say how well non-carbon bases would work, or whether there are alternatives to DNA-based life. I would guess, however, that the vast majority of extraterrestrial would be carbon-based, due in part to its sheer cosmic abundance but also because, from what I've read on the subject, it's just the element most suited by far to forming the complex molecules necessary for life to occur.

It seems more likely that now he just has a lot more time to think.

OK, so the consensus seems to be that the inside of such a sphere would be pretty much a 0g environment, since the gravitational attraction from the rest of the sphere will always be balanced... That's interesting. Thanks to all who replied.

If I built a large hollow sphere from an extremely dense material (dense enough so that the shell has noticeable gravitational effects) what would the gravity inside it be like? Would objects fall towards the inner surface, or fall towards the empty center? Or would they fall towards the inner surface, while their acceleration decreased the closer they got to it? I ask because visualizing this using the famous rubber sheet analogy (representing the sphere as a ring, since I'm removing a dimension in doing this...), it seems like the gravitational attraction should be towards the shell, regardless of whether you're inside or outside it - this makes sense intuitively, too, since the shell is what has mass... Visualizing it with gravity represented as "force lines", however, I'm not so sure.

Well, maybe it did have some truth to it. I admit I liked it, as a film, when I first watched it, anyway, but I just got the general impression that the message was "genetic engineering is bad." Some parts of it leaned more towards this sort of message than others, though. Like the bit at the beginning, where the prospective parents are talking with that 'gengineer', and the mother is looking very unsure while he's telling her all the benefits this child will have. Why would anyone have a problem with that? Admittedly, there might be some truth in the scenario the film presented, but those who do oppose progress like genetic engineering are often quick to cite Gattaca as support for their views, regardless of the intentions of the filmmakers, which I expect has influenced my feelings on it.

The thing with Tyrannosaurs only seeing movement comes from thinking dinosaurs were essentially just very large versions of modern reptiles, most of which, I think (such as crocodiles), lack colour vision. I'm pretty sure that more recently, though, evidence of some sort has surfaced that dinosaur vision was probably closer to bird vision, meaning they would have had good colour vision. So, the idea that T-rex could only see movement is quite outdated. Evidence for velociraptors as pack hunters comes from fossil arrangement (large groups around much larger prey, and such) and that the claw was probably best for clinging on rather than slashing, indicating that they overwhelmed larger prey by sheer numbers, causing them to bleed to death, rather than direct lone attacks. I think that's it, anyway. Apparently velociraptors were also probably one of the more intelligent dinosaurs, but nowhere near as intelligent as they were portrayed in the film. I remember being pretty disappointed when I found that out.

Gattaca was silly, anti-progress propaganda.

Ahh - my comment that they wouldn't interact electromagnetically was because I had assumed that they could make up a significant amount of the dark matter content of the universe, and so would be dark... Thanks for explaining.

They would? Doesn't that mean you could get supersymmetric atoms, and the like? In fact, if that's the case, what's to stop the formation of masses of supersymmetric galaxies, with a complexity rivalling their baryonic counterparts? (Except lacking interactions involving electromagnetic radiation, presumably).

I know we don't know exactly what dark matter is yet, but I assume there are some models which would describe potential interactions... Even if it doesn't interact with baryonic matter, I would think it might have some sort of interactions amongst itself.

How much does the particulate form of dark matter (WIMPs, supersymmetric particles, etc) actually interact? Could dark matter have some sort of analog to baryonic atoms and chemistry? Also, what relation is dark matter generally considered to have to dark energy? In the case that they are linked, somehow, what sort of relationship would this be? Would dark energy be a weak force like gravity, only apparent when dark matter accumulates in high enough concentrations, or could it be a more specific relationship, such as the byproduct of a "dark EM" of some kind?

Wouldn't the rays spread out more the further away the sun was? It's still pretty far from a point, anyway... Although it could also be partially an illusion because the gaps in the clouds are far away and look smaller.

You could assume a uniform density, in which case I think the formula would be [math]F = \frac{4\pi Gdrm_{2}}{3}[/math]. In this case, d = the density of the object and r = the radius of the object (d in your version of the formula). Of course, this will only work below the surface of an object, and assuming a uniform density probably won't be that useful, but I don't see any other way to do it in a simple manner.

Galaxies billions of light years away would have to have moved at over a million times the speed of light. Plus, the faster things are moving away from us, the greater the red shift. Things moving at the speed of light would be red shifted to infinity, I think. I'm not sure what this would mean in a practical sense, with these ridiculously superluminal galaxies, but we probably wouldn't even be able to observe anything more than 10000 light years away. It would definitely have very noticeable effects on what we're seeing now.

Ah, thanks. ...Is there a general consensus on the neanderthal issue, or is that still undecided for the most part?

The strong nuclear force holds quarks together, the weak nuclear force holds nucleons (protons and neutrons) together. The weak force is actually just a less direct effect of the strong force, though.

Thanks, everyone, that's pretty much answered my question. One more thing, though - if human subspecies were defined, where would it go in the name? Would "Homo sapiens caucasoid" make sense to say, for example, or would it be more like "Homo sapiens sapiens caucasoid". I assume the latter, since I'm fairly sure neaderthals are also classed as "Homo sapiens neanderthalis", but I think I've seen the former used, which seems incorrect.

Still, assuming there are no global catastrophes that plunge us back into a pre-technological age, we're probably nearing the point where our control over ourselves at the genetic level will override any potential for further evolution. Anymore significant changes to the human form, if they occur, will probably be intentional and controlled.

What, from a biological perspective, differentiates the various races of humans? I've heard it said that race doesn't exist from a scientific perspective, and that there can be more genetic difference between (for example) two white men than between a white man and a black man. While I assume the latter can be true in extreme cases, generally I can't see how this sort of viewpoint makes any sense. Human races evolved in different environments, and clearly there are differences, even if they are, potentially, only external ones. Of course, at the other end of the spectrum, there are those who claim that certain races are in some way more capable than others, and while such viewpoints are almost certainly biased, I assume there could be some differences between racial mindsets. The issue seems somewhat clouded, in any case.

Yeah, it works the same way the other way round... The water is cooled 1.5 degrees more, so more energy from the air can be transferred to the water. In this case, 4 degrees worth of energy more is transferred from the air, which only amounts to a 1.5 degree raise in the temperature of the water. That's a huge oversimplification obviously, but it's the basic idea.

Because it takes more energy to heat up water than it does to heat air, so, for example, what would amount to a 4 degree increase in the temperature of air would only amount to a 1.5 degree increase in the temperature of water. At least, I'm pretty sure that's how it works.

What version of Excel do you have? I'm sure you can adjust the ranges in it... Although I do remember using Autograph for something like that a while ago, and found it pretty useful. It's a month's free trial.