Sisyphus

What you're talking about is tensile strength, basically a material's resistance to being ripped apart. As said above, that's not the only measure of "strength." Certainly diamonds are harder. Also, that fact about spider silk needs to specify a thickness! Any material can stop a jet if it's thick enough. A quick google search turns up that fact, claiming a strand of spider silk once centimeter thick can stop a jumbo jet. (I don't know if it's true, but that's what it says). That's quite strong, certainly, but it's quite a bit thicker than any hair I've ever seen! Merged post follows: Consecutive posts merged It's called lonsdaleite.

We're not applying the moving-frame's contraction to the resting frame. We're applying the moving-frame's contraction to the moving frame. In the moving frame, earth-star has contracted to 2.23LY. Space twin thus measures his own trip as 2.23LY. Earth twin measures space twin's trip as 4.45LY. What is the problem?

It doesn't matter if the acceleration is instantaneous, actually. No, it does not follow. That's the key. The ratios between different lengths does not hold between reference frames. They are symmetrically and oppositely modifed. For example, each twin sees himself as twice the height of the other. Treat the Earth and destination star, at rest relative to one another, as a single object, with a dimension of 4.45ly. To the same degree that the space twin sees his brother contract, earth-star contracts as well. Earth twin sees the ratio between earth-star and space twin double, while space twin sees that same ratio cut in half.

The time dilation is symmetrical when there is a constant velocity between them. As they are moving apart, each does indeed see the other's time rate slow by the same degree. The reason it's different is in the shifting of frames on the part of only the space twin, by means of acceleration. And measuring in "space twin lengths" is indeed equivalent to what you're trying to do, i.e. claiming his metric in his own rest frame is somehow affected by his dilation in the Earth rest frame.

Well clearly those pictures will also be faked! As well the Lunar Reconnaissance Orbiter itself. Also, the Moon is fake.

Well, first of all, you are wrong, because the twin "paradox" has been experimentally confirmed many times over. So you shouldn't frame it in terms of "I think this is correct," but rather "why is this incorrect?" Anyway, I'm a layman myself and I've only scanned your post, but it looks like you're mixing frames incorrectly at a crucial point. You're saying the space twin actually has farther to travel because he's contracted. But again, he's only contracted in the Earth frame, which is irrelevant to his own experience of time and space. Also, you say "According to Earth-twin, space-twin's distance to the star is not 4.45 light-years, but 9.9 light years!" This is incorrect. According to Earth twin, space twin is flattened, but still traveling 4.45 light years at .866C. If the Earth twin, for some reason, was going to measure the distance in "space-twin lengths" while unaware that the space twin was contracted, only then would he consider the distance to be 9.9 light years. But if that were the case, he would also measure the space twin as traveling at 1.7C!

"God" was inserted into all sorts of things in the early Cold War as a further way to distinguish ourselves from the officially atheistic Soviet Union. Now that "terrorist" has replaced "communist" as the official bogeyman, it might be nice to see a rhetorical embrace of secular humanism in public institutions to contrast ourselves with the anti-humanist religious extremist ideology that drives our enemies. If it's just one group of religious warriors vs. another, you're not offering any real alternative, so everybody may as well just root for the home team, perpetuating conflict indefinitely. That's my problem this kind of thing (well, one of them). Whether it violates the establishment clause doesn't really interest me. There are other, better reasons for not waging jihad.

What high school did you go to that everyone learned advanced calculus very well?

No, it doesn't work. No perpetual motion machine works. EDIT: Haha, I see it's also a scam, and they want your money. Nice. Anyway, this is a common one. It's called an "overbalanced wheel," and people have been proposing it since the 12th century (says Wikipedia). What, fraudsters can't come up with anything original? EDIT AGAIN: Haha, I see they even admit it needs power to keep it moving, but "only a little." Well yeah, so does a regular wheel.

So they've decided to rename their opposition? They can do that? Why not just call them the Puppy Killing Democratic Party? Or the Big Stupid Jerk Party? Or the Armies of Sauron?

In the rest frame of the barn, the doors close at the same time, while the ladder is inside.

First of all, gross. More importantly, if you GE yourself to produce THC in such quantities, I'm thinking you're going to have all sorts of problems, medically. And if was already in your body in such quantities, what effect could breathing in some more of it have? And finally, if you think that's remotely a good idea, then you, my friend, have a drug problem.

Well, for one thing U.S. gallons are smaller than Imperial gallons - about 83% the volume. That accounts for some of the discrepancy, at least. Maybe it's also optimum efficiency vs. average efficiency? Something with "highway" and "city" mileage?

No. It generates only very small amounts of thrust. It's advantage is that it uses so little fuel (compared to chemical rockets), and so can fire continuously (again in contrast to chemical rockets, which are used up very quickly). The thrust is small enough (the ion engines that have so far employed have about as much thrust as the weight of a piece of paper) that it's really only useful in space, with almost zero friction and weeks, months, or years to accelerate. It wouldn't even move a car on the ground. And there would be no point, since cars have the advantage of not needing to be propelled by flinging mass out the back - they can push off the ground, with their wheels. It doesn't exist yet, though.

Yes, just not as toxic as the pathogenic bacteria that would be the reason your doctor is giving you those antibiotics. Nobody is claiming that all bacteria are harmful. You're the one making sweeping statements like "bacteria are good for you," and claiming you know better than medical science. It's like you're a bacterial lobbyist or something.

No offense, but this: makes me think you shouldn't be giving medical advice.

Right, right. I should say, you won't notice any difference in yourself. You will notice the rest of the universe changing quite a bit, however. Like the Andromeda Galaxy being flattened, multiplied in mass, only a few lightyears away, blueshifted into all nasty radiation, and hurtling towards you at nearly the speed of light. Which is a pretty big change.

The "constant acceleration" bit is tricky, too. It takes more and more energy to maintain constant acceleration relative to some other, inertial frame. If you are given an infinite fuel rocket and launch at a constant thrust away from the Earth, in the rest frame of the Earth your acceleration will taper off as you approach C, and you will get steadily more massive. But from your own perspective, your velocity is always zero, and you can keep adding energy indefinitely at the same rate, and you won't notice any change.

I don't know whether it's a legal issue with church and state, but that's not even really the point, as I see it. The problem is that Bush is constantly undermining our claim that we're not trying to wage a holy war, since that's apparently how he saw it. And in undermining the claim, we undermine the "war" itself. It's bad enough when soldiers on the ground try to prosletyze, worse when generals do it, and worst of all when it's the freaking President, who can't even be separated from "the United States" because he's the one giving the highest level orders. But I guess all this is old news. This is about current public relations strategy. The Obama Administration has shown signs that it just wants to sweep everything under the rug, to limit the damage as much as possible. Frank Rich thinks this is a bad strategy, because everything comes out eventually anyway, and if Obama tries to protect the image of the United States by protecting the previous administration, he associates with them and becomes tainted by them. Instead, he seems to want Obama to just completely disown Bush on behalf of America, kind of like Germany has disowned its Nazi period. Just stop trying to defend them, and say "Yes, this happened, but that's not who's running the show anymore, and we know it's wrong, too." Obviously, that approach has a lot of problems, as well. We can't just abandon the continuity of the United States for those 8 years. Are we not going to honor the commitments we made then, either? Of course we are. We're the same nation.

I would consider that one manifestation of irrational overconfidence. What could those "experts" know that I don't? My way of thinking must be right. After all, it's mine.

IMO, America's greatest strength is the same as its greatest weakness, and that's our irrational overconfidence. A runner up is an enormous sense of entitlement.

Ah, well, that's really just saying that gravity (or any force, actually), can only have one direction at a time. It's a vector, and two vectors add together to make one, third vector: the net force. So, the gravity experienced at any particular point at any particular time is the net gravity, which basically just means everything that isn't canceled out by gravity in the opposite direction. At the exact center of a solid sphere, or inside a spherical hollow at the center of a spherical shell, all of the gravitational force from the sphere/shell gets canceled out. For every point pulling you one way, there's a symmetrical point pulling you the other way with the same force, and you feel nothing.

Funny you should mention that. In fact, the highest point in Tuvalu is only about 4.5m above sea level, and I don't even speak Mandarin.

It's more than just how he looks, though, which I think is the source of most of the confusion in this thread, so it should be repeated. It affects how he is in another frame. It is more than merely an illusion. It's exactly as real as time compression - in fact, they're two sides of the same phenomenon. Just as in the twin paradox, they really are different ages at the end, in the ladder paradox, the length contracted ladder really does fit inside the barn that's otherwise too short for it. Even though the twin doesn't himself experience anything unusual, and neither does the ladder.

If you're asking if somebody who is moving at 0.99C relative to the Earth can kill you by looking at us and noticing the Earth is compressed, then the answer is no. If that's not what you're asking, then could you ask it some other way?