Cap'n Refsmmat

It would probably spin for a very long time. The trouble is that it's pretty much impossible to make a "perfect" vacuum -- one in which there are no particles at all -- so there'll be tiny bits of friction. Also, magnets gradually lose strength over long periods of time. It would be a cool toy to have sitting on your desk, though.

According to the people on Earth, yes. However, length contraction takes effect at such ludicrously high speeds, changing the distance he travels, and I don't know the math to figure out what that would do to his velocity according to his spaceship's speedometer.

Right. But who are we measuring the velocity compared to? For example, I could say that I'm stationary right now, compared to the Earth, but I'm moving at a ludicrously high speed compared to the sun, and the sun's moving at a high speed compared to the center of the galaxy, which is moving at some speed through the universe... For calculations like this you need to define your reference point, so to speak.

From what I gather, he's saying that adding CO2 will turn your sodium hydroxide into sodium bicarbonate.

No. Crazily enough, light always travels the same speed, regardless of how fast I'm moving. But if you were to fire a gun and measure the speed of its bullet, what you said may be true. Correct. But you asked a question about how different our version of a "second" is, and DrP is also correct. Let me explain. One common way of describing time is as a fourth dimension that we are constantly traveling through. Everyone moves "through" the time dimension. But whenever you begin to move through the other dimensions, you lose "speed" in the time dimension -- you essentially lose speed through time because you're speeding up in space. So you're going blazing fast through space but not quite as fast through time. Eventually, as you approach the speed of light through space, you're only inching through time. Does that make a little more sense? As Sayonara suggested, take a look at the links. Sisyphus' link covers some of this in better detail.

Or it means that time itself is passing differently for me. That's what relativity implies.

Yup. Yup. It's crazy, I know. Half of modern physics makes no sense, but somehow it's still correct. Sisyphus' link looks to be rather good, by the way, so I suggest you take some time and read through it. It'll be counterintuitive, yes, but that's modern physics for you.

That's dependent on the relative velocities of the two frames of reference. You can get the answer with the equations of special relativity.

Both his clocks and his body attest to him only spending ten years in space. Who's right? The people on Earth or the twin and his clock?

Let's suppose they're both born in 2050. He departs on his mission in 2075. When he returns, it's 2475 -- but the twin on the spaceship is 35. (Well, he has only aged 35 years, but he's clearly 425.)

Exactly. So I'm saying that you should put your shaft in a spaceship and send it off at a high linear velocity and bring it back, never changing its rotational velocity (from the perspective of someone sitting next to it in the spaceship). It'll still disagree with one sitting on the ground. Let me describe a scenario that you can visualize a little better. Suppose I take a pair of twins born eight minutes apart and put one of them on my latest new spaceship. I send him off at an incredibly high speed for five years; after five years, he'll turn around and come blazing back at the same high speed, for a total elapsed time of ten years from departure to return (according to him). So I send him off on my mission when he's aged twenty five. He comes back, aged thirty five, and sets off to find his twin to tell him how the journey was. Much to his shock, his twin died years ago -- in the time he was away, the twin had children, grandchildren, great-grandchildren, died, and so on. Four hundred years have elapsed on Earth, but the twin has only aged ten. That scenario is possible (assuming we could build such a spaceship). All of modern physics, and all of our experimental evidence, agrees that it could happen. What you are doing is denying all of that evidence and all of that physics. I suggest you take a course in special relativity to better understand it and learn why it has been demonstrated to be correct.

So don't change the rotational velocity of it then. Just change the linear velocity.

Probably around a hundred. revprez and atomikpsycho would make up most of those.

Cesium atoms don't decide to resonate at different frequencies, and quartz crystals don't start producing different frequencies at random (within a certain margin of error.) But I can absolutely guarantee that if you put your shaft on a plane and fly it at high speed, and compare it to a separate shaft on the ground, it'll show a slightly different answer. I defer the maths to someone with more experience in special relativity, as I am likely to screw it up.

I could give the exact same results with a sufficiently accurate quartz clock, an amazing pendulum clock, a calibrated hourglass, or one of your revolving cylinder doohickies. I'd hardly call that inaccuracy.

That is demonstrably wrong. Read this link: http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/airtim.html

But another guy at a different part of the universe with an entirely identical second-measuring-device would say his second was different than yours. That's just the way it works. Please go and read up on special relativity and the experiments performed to validate it.

I said it cannot be measured, because if I have a device that measures "real" seconds its results will vary depending on the reference frame.

But how do I know what that duration is if my clocks won't agree? The "reality" of the second is totally irrelevant if I cannot measure "real seconds" consistently across frames of reference. It's impossible to make a clock that counts in "real seconds". Physics is only interested in things we can actually measure or determine. A "real second" is not one of those things.

If it cannot be measured, what relevance does it have? You might say there's an absolute duration, but there's no way for us to determine what it is. We're dependent on clocks. The absolute duration is irrelevant to our physics. http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/airtim.html

And how do you define a "real second"? None of your clocks will agree.

If I get myself two atomic clocks, the accepted standard for timekeeping, and synchronize them as exactly as possible, I can then stick one of them on a spaceship and be certain that they'll continue to agree with each other. (The atomic clocks are similar to your rotating thingummy.) I can then have the spaceship fly away at 0.5c for a year or two and return. Guess what? When you compare the clocks (like your rotating doohicky), they won't agree with each other on how much time has elapsed. Which clock is the "correct" one?

There is no universal second measuring device. I could observe your "universal" device from a different reference frame and get a different answer than you get in your reference frame -- even though we're looking at the same device.

It's plenty controversial, as far as I'm concerned. I regularly meet people who don't "believe" in global warming and think it's all a fraud.

It's not boiling the water. Take a look at the Wikipedia article.