Moderator: Flannel Jesus
PhysBang wrote:You can work this out for yourself or read up on relativity theory in a good book.
MrMermaid wrote:I'd like to add that as the train wheel is rotating, the point of contact of the wheel with the track has a speed relative to the ground of 0, and the uppermost point of the wheel has a speed relative to the ground of 2v. So the length contraction of the wheel isn't into an oval compressed in the x-axis, it is much more complicated. Does this help to account for the constant 1000 spins over a contracted length of track as measured from the train? As the train approaches c, does the wheel eventually stop spinning? I lay no claim to knowledge of answers to these questions; maybe someone else would care to enlighten me?
James S Saint wrote:And yes, time dilation in the direction of motion must bring the spin to a stop as any spinning object reaches light speed. Interestingly, the transverse spin does not change. And even more interestingly, what that means is that every atom in an object moving near the speed of light, will form a magnetic dipole and become a magnet. Even a block of wood, would develop a magnetic field and crush itself. The properties of materials completely alter at extreme speeds.
In other words, you can't.
Typically just words without substance. Try explaining it in detail.
James S Saint wrote:Note that we had to recalculate our distance measured by the train because to get the same velocity v, we had to change dx’. But what if the train merely accepted that it was going at a different velocity, v’ rather than a different distance? What if;
v = dt/dt <> v’ = dx’/dt’
If the train were to accept that it was going at a different velocity, then it could accept that the track is really 1000m just as the station measures. So how do we know which to accept? Do we say the train will see the track as shorter, or do we say that the train will see its velocity as more than the station measured? How do we decide?
MrMermaid wrote:I think I've come to a conclusion about your refutation of S.R.
Essentially as the wheel is turning relative to the train, with a velocity of v at the circumference of the wheel, the entire wheel's circumference contracts by an equal amount as viewed from the train: the wheel's radius gets smaller, and is indeed proportional to the amount by which the track (as viewed from the train) gets shorter. The wheel still rotates 1000 times. Paradox resolved, case closed. Sorry.
MrMermaid wrote:James S Saint wrote:Note that we had to recalculate our distance measured by the train because to get the same velocity v, we had to change dx’. But what if the train merely accepted that it was going at a different velocity, v’ rather than a different distance? What if;
v = dt/dt <> v’ = dx’/dt’
If the train were to accept that it was going at a different velocity, then it could accept that the track is really 1000m just as the station measures. So how do we know which to accept? Do we say the train will see the track as shorter, or do we say that the train will see its velocity as more than the station measured? How do we decide?
How is this even possible? Are you saying that the rate at which an observer, motionless with respect to the track, measures the train to be travelling at, will differ from the rate at which an observer on the train will measure the ground to be speeding by? This is nonsense.
MrMermaid wrote:Think of it like this:
On the roof of the train, there is a sodium light bulb. There is an equivalent bulb hanging over the tracks at the station. Also on the train is an observer with a spectroscope, and there is a second observer with an equivalent spectroscope at the station. As the train approaches the station, the observation of the light from the train's bulb by the observer at the platform will show that the spectral lines of the sodium bulb have been blue-shifted, proportionally to the velocity of the train. The observer on the train will see an exactly equal blue-shifting of the light from the bulb at the station. This is obvious, and easily experimentally tested. There's no need to measure lengths to calculate relative velocity; one can do it purely using this method. This avoids any question of whether the observer on the train can measure a different velocity because of the length or time dilation issues - it's impossible. Plain and simple.
James S Saint wrote:Oh you brought that up too soon in the thread. I would run across the one bright guy so soon. You have a good point (I think) that if a spinning ring dilates to an observer, it will appear to have a shorter circumference. I will have to calculate to see if it matches the track properly. I am just trying to come up with situations to bring out an error that I know is there already due to other issues. Perhaps this is insufficient.
Lorentz assumes distance dilation
Saint assumes velocity dilation
The only question is which of those cannot fit the rest of reality without making even more non-intuitive assumptions, if either.
Special relativity says the speed of light IS consistent (not merely observed to be).
Saint says the speed of light is not consistent, but will merely be observed to be.
It is an issue of two wrongs may not make a right, but lefts will. The question is who is really making the 3 lefts?
It is similar to Galileo and the Church concerning the Helical universe.
PhysBang wrote:Well, it is similar up to the point that the Church had power, whereas you don't have any power to silence SR. Oh, wait, you think that you are Galileo. OK, then, the scenario is similar up to the point that Galileo had empirical evidence and you have absolutely none.
Farsight wrote:Just use an electron. We create an electron out of light via pair production, the electron has spin angular momentum, and the Einstein de-Haas effect tells us this spin is real.
So what's going round and round? Light. It's just a circular version of the back-and-forth motion in the simple inference of time dilation.
So you've got light going round and round at the speed of light in a circular path. Then when you move the train the light path is helical. If you move the train at c the light can't be going round and round any more.
James S Saint wrote:Actually you could use light wheels for the scenario if you made the track out of a series of light wheels rather than a fixed rail. Or even if the rail itself was moving at a slower rate to allow for the train to not be exceeding the speed of light.
And Phys, read a book. Lorentz doesn't deal with transverse motion.
And then yet a fourth way is to have a reflective optic ring mounted on top of the train where both station and train could count the spins of the photons around the ring.
The train, seeing no change in the ring and taking only 9 seconds to make the journey, would count a certain number of spins. But the station, seeing the ring as a dilated oval would see the distance for the photon travel to be less and thus yield more spins. And in addition, the station reads that it took the train 10 seconds to make the journey and thus not only is the path of the photons shorter, but the time allotted is longer and thus reads considerably more spin counts.
And a fifth way is to have the station with a separate photon ring of its own. The station counts a certain number of spins in 10 seconds while the train, reading its own identical spin counter counts less in the 9 seconds the journey takes (transverse or not).
Using an absolute frame of reference, the following diagram displays the effects of spectrum shifting.
As the railcar views the light coming from the station, it sees that light through 2 types of filtering, Doppler shifting (D) and Time dilation (T). The effect of the Doppler shift due to the train approaching the station is that the frequency of the light is increased to what the absolute frame would have produced. But the effect of the Time shift due to the train approaching the station would also increase the frequency because the train’s time is running slower, thus blue shifted.
How many ways do we have to prove that it isn't the Lorentz distance that is changing.
James S Saint wrote:Phys, learn SR yourself. You have displayed many times how little you know while demeaning anyone else. Do you ever say ANYthing that isn't BS?
I haven't "just quit" any thread. Since you and Carl were stuck on Lorentz in the Stopped Clock paradox, I went ahead and deposed Lorentz in this thread as a separate issue. In that thread, Lorentz isn't really the issue. The paradox is in SR without Lorentz. SR and Lorentz are different things. If you use Lorentz to defend SR, you merely use a false presumption to try to escape the paradox.
In this thread, I have used Lorentz only to display how Lorentz equations force an error and different paradox.
In this thread, I accept time dilation and show how you cannot accept length dilation.
Farsight wrote:Don't feed the troll, James. He's just trying to spoil the thread and deter readers and contributors.
Farsight wrote:The length contraction isn't as bad as you think. It's an observer effect rather than something real - we know this because a star a billion miles away doesn't flatten to a disc just because you accelerated your gedanken spaceship. As to how it works, imagine that you're a circle of light. When you move fast one point on the perimeter of that circle traces out a helical path. When you then look at all points and integrate, the circle is "smeared out" into a cylinder. You are this cylinder, but you don't see yourself as such. You still see yourself as a circle. There's a scale-change here, you see everything else as length-contracted, because you're smeared out. So if I'm another circle, I look flattened. And of course you can assert that it's me moving not you. Then it's me who's smeared out, and it's you who looks flattened to me. Symmetry.
Return to Science, Technology, and Math
Users browsing this forum: Google [Bot], MSNbot Media