Cap'n Refsmmat

What do you mean by "assume"?

Yes, I am.

We do have a good standard of time. Light also travels at the same speed in all reference frames, so it doesn't really matter if time dilation is occurring.

What does it matter? You measure the speed of something in units which are either predefined or you define. How do I know which clock is right? You are assuming there's some absolute "second" that's the same everywhere. There isn't. Time itself passes at different speeds in different reference frames, making clocks seem to go faster or slower. The trouble isn't that we don't have a good standard of time -- it's that time doesn't play by simple rules. You don't have to break your tape measure, and the standards never change at all. They're the same. It's just that time (and space) change at high velocities.

Motor Daddy: I don't disagree with you. The trouble is that if I produce two devices that can measure time accurately according to the standard, and stick one on Jupiter (gravity affects time) or on a spaceship, it'll disagree with one that's been sitting on Earth. Time dilation is a real effect of motion, and it's not because my clocks are messed up by being flown at high velocity. I could build all sorts of high-tech clocks and they'd do exactly the same thing. Time dilation reflects reality.

Some fancy math determining the output from a given magnetron, I'm guessing. (At least that's how they'd design it.)

Yes, but it's something you're deriving. Frequency also has a time element (cycles per second).

Perhaps they recently relandscaped the courtroom.

You don't need to measure the duration of the event. The frequency of a wave equals its wavelength divided by its speed. Find the frequency (which is known for a microwave) and its wavelength (the two points on the chocolate) and you've found the speed. The point with SR is that I can make the same measurement while flying in a spaceship at Ludicrous SpeedTM and get exactly the same answer. Suppose we developed a microwave gun that could perform mooeypoo's experiment from afar -- aim the microwave gun at the chocolate from far away and you can perform her measurements. Then we go out in space and set up a space station with the microwave gun aimed and ready, then launch another spaceship at Ludicrous SpeedTM past the spaceship, the microwave gun aimed at it as it flies away. You'd assume that because the spaceship is going Ludicrously FastTM and the light is only going a little faster, the light would struggle to overtake the spaceship. But if I were sitting on the spaceship with the chocolate bar, I'd still get the same answer -- it's as if I were sitting still. Do you understand what I'm trying to explain here? (You don't have to see how that could happen. It's not supposed to make sense. I'm just asking if I was clear.)

http://www.scienceforums.net/forum/showthread.php?t=33703 You can measure it without knowing what a meter is -- you just need any system of measurement. Cubits will work, if you don't mind defining the speed of light in terms of cubits.

Taggart: I got it! I know how we can run everyone out of Rock Ridge. Hedley Lamarr: How? Taggart: We'll kill the first born male child in every household. Hedley Lamarr: [after some intrigued consideration] ... Too Jewish. - from Blazing Saddles

1. Nothing can go faster than the speed of light in a vacuum. It's the speed of light in that particular medium that can be broken, causing Cerenkov radiation. 2. From the observer's frame, the light's traveling at c and the spaceship at 0.5c. From the spaceship's frame, the light is also traveling at c and the spaceship is stationary.

You also need to remember that light isn't transmitted like sound is, by molecules and atoms bumping together and vibrating. It's transmitted by moving photons. When photons hit atoms, they're absorbed and then re-emitted a split second later, so denser materials make light slower. (Just remember that the photons themselves always move at the speed of light, c -- the light is slower because of the delay between being absorbed and re-emitted.)

I wonder if "marital unfaithfulness" encompasses more than just cheating. The Bible requires dedication and obedience to the husband, and so on, and breaking that might be considered "unfaithfulness". I don't know. I'm not a Bible scholar. Just throwing it out there.

We use radio telescopes (and all sorts of other kinds of telescopes) for "listening" to the universe. Radio would certainly work as a way to guide spacecraft. Most modern spacecraft receive guidance information by radio.

The trouble with sound in space is that there is no air for the sound to travel through. Space is silent.

According to Wikipedia, Catholicism has certain limits on prenups: http://en.wikipedia.org/wiki/Prenup#Catholicism

You seem to have a loose definition of proof. Try taking on yourdadonapogos' word challenge. We're already cluttering this thread with off-topic posts.

You don't seem to.

Seven hours. I suggest you drop this line of questioning, as it's totally irrelevant to the main point of the thread. It's a thought experiment. Try it.

No. Let's suppose the balls are approximately 10 meters away from each other. That gives a gravitational force between two of them of [math]F = \frac{G \cdot m_1 \cdot m_2}{d^2} = \frac{6.67\times 10^{-11} \cdot 1 \cdot 1}{10^2} = 6.67\times 10^{-13}N[/math] That'll accelerate the two affected balls by approximately 6.67 x 10-13 m/s2: [math]6.67\times 10^{-13} = 1 \times a = a[/math] 6.67 x 10-13 meters per second squared of acceleration is a very, very tiny amount, even with another ball also contributing the same amount. They'll take a very, very long time to the velocities of the balls. [math]v = at + v_0[/math] [math]0 = -6.67\times 10^{-13} \cdot t + 100[/math] [math]t = 1.5 \times 10^{14}s[/math] That's somewhere close to five million years to slow the balls to a stop. (We're assuming a reference frame where they're moving, of course. In the frame where the balls are stationary it would take five million years to get them moving at 100m/s towards the other balls.)

Gravity is weak, and unable to overcome the motion of the balls (well, it has a tiny effect, but we really don't care).

And I might point out that we had specified a constant velocity for the train.

From every reference frame except the train's the ball is stationary at that point, unless a squirrel comes along and thinks it's a nut. From every reference frame, only one object is moving and it is moving at a constant velocity. How am I basing the ball's velocity on the train's velocity?

Why's that? If you give me a situation with clearly defined parameters (the train's going at a constant velocity, etc.) I can predict what will happen next. Is that unreasonable?