Sisyphus

It's possible, because since the time the oldest light we see was emitted, space has expanded to many, many times it's original size. So the objects we see with that ancient light were much closer than 13.7 lightyears at the time we're seeing them, and by now are much farther than 13.7 billion lightyears.

Yeah, defining death is surprisingly arbitrary. I've heard doctors say, "Death is a process, not an event." Certainly people who are clinically dead are revived all the time, and the legal definition of death varies from place to place.

Or any force with perpendicular relationships, for that mater. Which is to say, pretty much any. Perpendicular motion is always unaffected by the application of any force. Hence horizontal vs. vertical. pyxxo seems to deny this, insisting such things are merely artifacts of definition. Or the more fundamental fact of simple multiplication. Length, width, and depth are perpendicular dimensions, and any none-perpendicular coordinate system, though possible, will greatly complicate the math of physical description. Like with those carbon nanotubes - ok, so how long is the tube, and how thick?

I say just ignore them. It's true, they're hypocritical, and largely empty of content, and this particular meme probably won't last. The only way it could matter is if it stirred up enough vague populist anger to swing a few elections, but it will fizzle out before November 2010, when we'll be talking about some other stupid non-issue instead. Hey, did you hear that Obama asked for DIJON MUSTARD?!?!?! LOLZ!!!!!!!!!!!!!! http://www.youtube.com/watch?v=GaYLo76RrEE

Please follow the link. http://en.wikipedia.org/wiki/Ladder_paradox I'm not mixing reference frames. 1' is 1' for you, but your 1' is not my 1'. No. You seem to be confusing reference frames with actual objects. They're not. They're just metrics. You can pick any reference frame you want. It's arbitrary. Whether there is anything at rest in it doesn't matter in the slightest. So yes, there are an infinite number of reference frames in which the Earth is moving at >0.999999999999999C. They just tend not to be very convenient. But it may interest you that there are, in fact, plenty of particles moving at more than half C relative to the Earth that collide with the Earth all the time. In fact, these allowed us to have some of the first direct observations of relativistic time compression.

It's not that I completely disagree, but can't that be said about anything? Most of the time, a court of law has much, much more time to consider a defendant's conduct than the defendant himself did at the time of the actions under consideration. That doesn't get him off the hook for anything, though. Nor does ignorance of the law. Sometimes judgement is more lenient if there are convincing mitigating factors, but not necessarily, and never completely. Analyzing actions with the benefit of hindsight and distance is fundamental to the process. As is civilian oversight of the military, for that matter.

I think it's just a matter of getting used to the idea that length is not an absolute, but dependent on the system (reference frame) in which it is measured. This isn't a great analogy, but if you spin clockwise as seen from above, you're spinning counter clockwise from below. This doesn't mean there are two of you, or that you're spinning two directions at once and thus getting twisted into pieces, or that one statement has to be false or illusory. It's just different, depending on the orientation in which it is considered.

You can't be traveling at .9C. You can only be traveling at .9C relative to something else, and that something else will be traveling at .9C relative to you. Anyway, it won't kill you, because you're not experiencing it. It's someone in that other reference frame who is experiencing your odd condition, and you who is experiencing theirs. But that doesn't make it illusory - you really can fit that other person inside a smaller container, etc. They really are that small, in the appropriate reference frame. Much like their time is moving slower in your reference frame, but they don't experience anything unusual, except when they look at you and see your time moving slower.

I don't really know what you're getting at, here.

One of my best friends is currently doing autism research at Columbia. Apparently a ridiculously large part of her job is correcting misinformed (and very often belligerent) parents of autistic kids. It's bizarre. Let's hear it for celebrities advocating actual science!

But with relativistic velocities, it does shrink, in the applicable reference frames. It's not just an illusion, as with a mirror. A twenty foot pole moving fast enough will fit inside a ten foot room, in the reference frame where the room isn't moving. Of course, in the reference frame with where the pole isn't moving, the pole is still 20 feet long, and it's the room which has shrunk. Believe it or not, this actually doesn't cause a paradox: http://en.wikipedia.org/wiki/Ladder_paradox Interesting. I don't know, but I'm thinking it can't work the same way as motion, if only because at some point they'd all have infinite momentum, and then beyond... Oh, and it's not caused by motion relative to the CMB. "At rest with respect to the CMB" is convenient but not priveleged. It's caused by motion relative to whatever reference frame it's considered in.

Yeah, I'm not in the military or anything, but the oath to follow orders seems pretty clearly conditional upon the legality of those orders. The oath to support and defend the Constitution, however, is not conditional. So theoretically, there's never a Catch-22. In practice, I'm sure you could still get yourself in very serious trouble for refusing an unlawful order, but you would be unambiguously in the right, granting that the order was in fact illegal.

I'm thinking it's not inherently harder to grasp. If we all grew up on a group of independently moving asteroids instead of all together on this seemingly solid planet, I think we'd probably find the idea of "real" motion as distinct from relative motion totally bizarre.

Yes and no. Your length and mass are frame-dependent. In a frame in which you are moving, you are compressed and densified. There is no reason to choose one frame as “real” and every other frame as “just appearances,” so you are both. However, what you personally actually experience is always going to be your own rest frame, in which you have zero velocity and thus zero compression, etc. Again, though, that’s not to say that frame of reference is somehow more real than one in which you’re moving at 0.9999C, and have all sorts of wacky stuff going on.

We're also already moving at 0.9999999C in various frames.

He doesn’t experience length contraction or increased density himself. This is a matter of keeping in mind your reference frame, and remembering that there is no such thing as absolute velocity, only relative velocity. He isn’t moving relative to himself, obviously, so in his own reference frame his own velocity is zero. If he’s moving that fast relative to, say, the Earth, then he will be contracted and have increased density in the reference frame in which the Earth is motionless. In his own reference frame, though, it is the Earth which has increased density, and which is flattened.

Airbrush, I was using a simple example of space expanding at a rate of 1 inch per foot per second (which is obviously very very very much faster than the actual expansion), as a way of explaining why things farther away appear to be moving faster. I mispoke (miswrote?) in one example, and Martin corrected me.

I think the apparent pseudo-worship and the accompanying endless arguing over what the "founding fathers" would have agreed with is in great part a remnant of deliberate efforts to form the national identity and mythology of a young nation with an inferiority complex. We didn't have a long history, we didn't have a monarch, we didn't have a universal religion, we didn't even have any solid reason to believe the whole thing was even possible. So those particular men, the key figures in the founding, were the the best we could do, and so we deified them in the national consciousness. Part of it, though, is that the founding of our country was a radical experiment, and the whole thing is based around the ideas that these guys based off of Enlightenment philosophy, refined and debated amongst themselves, and audaciously put into actual practice. So we're actually living out their ideas, which makes them of great interest. The foundation of the country is our Constitution, a document detailing their intentions. So it's not so strange to debate what their intentions actually were, even if technically it doesn't really matter.

It's a shame that you're done here, since all of those objections in your last post actually have pretty easy and straightforward answers. It's a bigger shame you began the conversation by declaring that you would never change your mind - the very definition of closemindedness. Why even have a discussion? It's like saying, "Teach me about arithmetic. Keep in mind, though, that I'll never accept that 3+4=7." What is anyone supposed to say to that?

Never had one. Don't see the point. Neither, as far as I know, does anyone else I know close to my age. We call people, not locations.

I don't understand. Without further experiment, how would you know that C is constant relative to to the observer, as opposed to relative to some aether medium, the source of emission, or the nearest big mass? I understand that isn't what they were trying to do. You're saying they should have known their expectations were wrong? What's the significance of MM, then? I was under the impression that it was the first real experimental evidence that C is observer-dependent. Am I wrong? If you say so.

That's not the reason why. It would not take more and more energy to accelerate as you go along, first of all, and you would never ever get any closer to C, from your own perspective. Remember, in your own reference frame, you always have zero velocity. From someone watching on Earth, your acceleration would taper off as your velocity approached C, but that's from Earth. It would take ridiculous amounts of energy because 1 G is actually a lot of acceleration. Think about it. After 1 minute at 1G acceleration, you're going 1300 miles an hour, literally faster than a speeding bullet. And you want to maintain that amount of thrust for years?

Surely this isn't correct. The sun is accelerated by the Earth just as much as a feather would be at that distance. Sure, Earth-Sun comes together faster than Earth-feather, but that's because the Earth falls towards the Sun much faster than it falls towards a feather. Or is that what you meant?

That would also give you craaaazy relativistic time compression, exponentially more the longer the trip. Like, a few decades travel, ship time, to other galaxies. The problem is that one G of thrust is actually a whole lot to sustain for very long. You'd need ridiculous amounts of energy.

Well, this is new.