Sisyphus

I enjoyed all the analysis about the beer choices. (Bud Light for Obama, Red Stripe for Gates, Blue Moon for Crowley.) Personally, I would have served them all from a keg of Arrogant Bastard Ale, and let the pundits make of that what they want.

Not proposing anything but a thought experiment. But sure, "wall off half the universe." I'm walled off from at least half the of it right now, actually, just from sitting on a planet. Of course, there is still radiation from the "wall" itself, which could never be completely eliminated. But in any case the point stands. It's not your velocity that is the problem (inasmuch as there is no such thing as absolute velocity), but the fact that something else is approaching you at a very high relative velocity and thus radiating especially nasty photons at you. And that seems practically unavoidable in our own neighborhood once we ourselves are moving at very high velocities relative to the Earth (and, consequently, the cmbr). Or is it? You're moving at arbitrarily high velocity relative to cmbr. An arbitary number of shield walls (at arbitrary distance from one another) is moving ahead and with you, each slightly slower than the last, so each is approaching both its adjacent walls at an arbitrarily small velocity. Problem solved?

No, the wall is at rest wrt the cmbr. The probe is approaching it at nearly C.

Clearly you should measure your volume via displacement in the bathtub.

Well that's where my giant wall comes in, to block it out in the forward direction. Would that not work?

Well, look at Europa. It has an induced magnetic field, and varying tides from orbital eccentricity and the other moons' influence, despite being locked. It's not "habitable" in the sense that human beings could walk around unprotected, but its subsurface liquid oceans are quite possibly habitable to Earth-like life.

Whether the appendix will disappear depends on which effect is more important to reproductive success. The "reboot" capability insane_alien mentions, or the occasional death by appendicitis. My guess is it will evolve to take on its new role better, and decrease the instances of appendicitis.

Hydrogen would be the lightest gas. Vacuum, obviously, is lighter, but comes with lots of problems. A gas like hydrogen exerts pressure, supporting the structure of the balloon. Something "filled" with vacuum wouldn't be a "balloon," since it would have to be rigid enough to support its own structure against the outside air pressure. This would be a lot harder to build and, presumably, heavier. As for minimizing weight, that's not really the issue so much as the ratio of overall weight to overall volume, i.e. density. The same shape scaled up has a bigger ratio of volume to surface area (it goes up by the 3/2th power). Since it's the internal volume, filled with hydrogen, that's going to be the lightest, and the surface (the balloon itself) where most of the weight is, you'll decrease density by increasing overall size. I don't see any obvious limits to how big you can make it. Air resistance shouldn't matter at all.

But then you'd have to have clearly defined generations, and homogeneous generations. That's not going to work, either. You could, perhaps, have every single individual as a "stage," with many coexisting, and the "branches" constantly weaving back together most of the time...

And how is that?

Why? Because the CMBR will be so blueshifted in the "forward" direction that the photons will have enough energy to bla bla bla? That's not velocity that's doing it, then, it's the fact that it's in the path of extremely high energy radiation. You could just as easily say "as long as it doesn't hit anything," which is the same as saying "being motionless won't cause you to disintegrate, as long as nothing moving at 0.9999C crashes into you." So build a huge wall at some arbitrarily large distance away, and fling your probe in its direction at a relative velocity of 0.9999999999C.

Thus the difference between an influential scientist and a prophet. See also: the widespread belief that there's something called "Darwinism."

Might make good coffee table books. I don't think I could actually read them, though.

g(n) is standard gravity, defined as the acceleration due to Earth's mass at sea level, at 45.5 degrees latitude. g is local gravity. It changes depending on where you are. Neither is affected by the presence of atmosphere.

In addition to what iNow said, this is also wrong. 6.673*10^-11 is the gravitational constant, as measured in (m^3)(kg^-1)(s^-2), not m/s^2. It's what appears in equations as G, and is not a measure of force or acceleration. The 9.8m/s^2 is the approximate acceleration at Earth's surface. Force of gravity between two objections is determined by the equation: F = (Gm1m2)/r^2, where F is force, G is the aforementioned constant, m1 and m2 are the masses of the objections, and r is the distance between their centers of mass. See: http://en.wikipedia.org/wiki/Gravitational_constant

What's the alleged mystery about the Mariana Trench?

It was my understanding that BMI is seriously flawed, mostly because it doesn't take into account percentage body fat. A professional athlete and a big fat guy can have the same weight and height, but one gets the weight from muscle and the other fat. As for your actual questions, I'm right about in the middle of "normal" according to BMI (don't know my exact weight), and I don't have any suggestions beyond the obvious - portion control, take the stairs, etc.

Ahhhh, my conspiracy theory bingo card just exploded!

And you say that based on what? Sunlight, and sunlight unfiltered by an atmosphere reflected off the nearly white lunar surface A few things to remember. First, there is only 1/6 the gravity on the lunar surface as on Earth's surface, and it drops off much quicker, as the Earth has 80 times the mass as the Moon. The lunar module only used 3500 pounds of thrust to take off, and that was twice lunar gravity. Second, there's no atmosphere on the moon. You're never going to have clouds of dust suspended in air. If you throw up a handful of dust, each particle just follows a perfect parabola and falls right back to the ground. Finally, the ascent module took off from the descent module, not the surface. Based on? Based on? No, I haven't downloaded your video, but I've seen several making the exact same claims.

So you see things about the moon landing you don't understand, and your first response is not to ask why it's like that, but to assume an entirely different explanation, to which you apply no skepticism at all. This is a common trap people fall into. In this case, focusing on peculiarities in photographs (all of which are easily explained, as a cursory seach could tell you), while not even questioning the plausibility of a 40 year conspiracy of tens of thousands of people that to this day has fooled even those people most able and with the greatest motives to cast doubt on it.

Since we only have one example so far of a planet with life, it's hard to say what's necessary, what's an advantage, etc. In other words, if Earth were different in one of those ways, would there be no life possible, or could there just be different kinds of life? Since the only life we know evolved here, everything kind of looks like an advantage, for us. What you've got is a list of things that would make life more difficult or impossible for us, if Earth were that way instead of the way it is (the way that led to us being here to wonder about it).

The proof that they died more than they reproduced is that they're extinct now...

As Mokele said, it's something that triggers pleasure. Why it does depends on the person, how you came to it, etc. I might suggest you think of it in more general terms. For example, we're not evolved to work on cars, obviously, but we are evolved to solve problems (and to enjoy doing so), and we're evolved to appreciate the feeling of power that comes with a kickass car. As for why you specifically enjoy the specific activities that you do, nobody can possibly answer that without having witnessed and analyzed every moment of your life so far.

Actually, we know a lot about it. But you'd have to ask a paleontologist about that. If by "transit another species" you mean evolve into something different, then yes. By definition, our "ancestors" didn't go extinct, because we're still here. That isn't what happened. It was artificial selection. Only the least aggressive foxes of each generation were permitted to breed. Over many generations, they became naturally much friendlier towards humans. The changes in their appearance were unexpected, the result of genes tied to the ones that made them less aggressive. I don't see how this is related to the rest of this thread. Please explain.

Maybe you could give an example of the kind of thing you're looking for? Are you asking why a species becomes extinct? That depends on the species. Less food, more predators, conditions changing faster than the species can evolve - all result in more deaths and fewer surviving offspring, so the population shrinks. If it shrinks too much, it goes extinct. The dinosaurs, for example, probably mostly died off because a large meteor impact radically altered the global climate in a short period of time, and most couldn't survive the new conditions. Of course, the more literal answer to the question in the title, why did our ancestors go extinct, is that they didn't. They evolved into us.