swansont

I have a vague recollection from DS9 about gold-pressed latinum being used as an exchange medium, and that it could not be replicated for some nebulous reason.

It is a huge leap of flawed logic to go from "I can't explain this" to "that was a ghost/UFO/Elvis/whatever." If you don't have enough evidence to explain something, the only scientific conclusion is that you don't have enough evidence to explain it. "Science can't explain it, therefore it was a ghost" is based on a flawed premise.

But the effect has been seen using different values of v and h. All consistent with prediction. But the effect was not symmetric with the motion with respect to the earth. How, mechanically, do the clocks know they are going east or west? Atomic clocks are shielded to protect them against fluctuations in magnetic fields. GPS satellites confirm this continually, as do clocks on other satellites of differing orbits, which are subject to different conditions. Other (non-atomic) clocks are simply not precise enough to show any effects, but it has been demonstrated with different atomic and nuclear transitions.

But you get the same effect if you use a rubidium clock instead of cesium. Or a hydrogen clock (maser). So the response of the atoms scales with the transition — it's not e.g. a constant effect for an electron (i.e. it's not consistent with just a certain force acting on the electron, causing a constant energy change). The effect is cesium is about 1/5 as large in hydrogen and 2/3 as large in rubidium, because they oscillate at different frequencies. Not to mention that it's completely consistent with an effect that has to be there in order for electromagnetic waves to exist in the first place (wave equation solution to Maxwell's equations)

Right. If the source is passing by at some distance, rather than coming right at you, there's going to be a cosine(theta) term in there somewhere, and that angle will change in time.

But that's not what "it" says. The speed of light is constant in all inertial frames.

It is, and that causes problems if you aren't careful. You get the Sagnac effect, which makes it look like the light is travelling at c+v or c-v for motion with or against the rotation, if you are analyzing things in the accelerating frame. Which tells you you aren't in an inertial frame, where you should get c. But if you account for this, and do your analysis in an inertial frame, you should be fine.

Fredrik's response looks much like the Lorentz response to the Michelson-Morley experiment, about the ruler shrinking in the direction of motion. It was discarded not because it was wrong, but because it was ad-hoc and had no mechanism that could be tested. Einstein came along with a mechanism, and that allowed testable predicitions. That's what is needed by science.

And that's the geeky punchline of the joke. No work = no pay, and yet you have expended tremendous energy.

Or, putting the first phrase of Sisyphus' post another way, the laser is also travelling at 250,000m/s around the galaxy. What matters is motion of the laser with respect to the earth, and there is none. And there are no priveleged frames, etc. etc. Oh, and the momentum of light is E/c. A moving source or target will see an energy (or frequency or wavelength) shift, rather than a speed change.

Ideally, stationary with respect to the floor, with arms perpendicular to the body. But really, if you're going to personally hold a piano stationary for eight hours, it won't matter what position you use; from a physical statndpoint I don't think anyone can do it, and (more importantly) there's no work done, which is why others have offered a multiple of what I would pay.

What is/are the "it" to which you refer here? I haven't reread the thread, but don't think anyone is contending that the speed of light changes in a cyclic fashion.

You take into account the path delay from finite speed of light when you sychronize clocks. You adjust the reading by t=d/c. Time dilation is different — the rate of the clock is changed, not just the reading. Always lagging by a second is not running slow. Running slow means continually losing time over repeated intervals. My watch, for example, runs slow as compared to the US Master clock — it loses about 1 second per day. So if I synchronize it today (taking into account path delay), it will be behind by a second tomorrow, and two seconds the next day, and three the day after that. Of course, if you can measure the change in rate, the clock becomes useful again, which is what happens with GPS satellite clocks. They run fast (from kinematic and gravitational dilation effects), but the synthesizer frequency is adjusted to compensate.

I think you have a sign error. I believe it should be [math] c \frac {\frac {f_0^2} { f_e^2} - 1} {1 + \frac {f_0^2} { f_e^2}} = v [/math] If you want to double (or halve) the frequency, go 3/5 c

Yes, it has been observed in muon decay, which is a standard relativity example. That's mediated by the weak force. But the same effect happens in atomic clocks, which are mediated by the electromagnetic force. (And with different atoms, with different transition frequencies). The scaling is all wrong for it to be a physical effect. Bzzzzt. Sorry, that's shifting the burden of proof/appeal to ignorance.

This would apply to any transverse motion if it were correct. I mean, "vertical" really has no meaning on a spaceship. So it sounds like you have to anticipate where the target will be in order to properly align the trajectory. You've introduced a preferred frame, and an actual experiment testing this would fail. e.g. lasers traveling a significant free path (several meters) and then aligned into micron-sized optical fibers should become misaligned after 12 hours because the alignment relative to the motion of the earth around the sun has changed.

But saying that time slowed is actually simpler. If you say that all processes slowed you need to come up with a mechanism by which various processes would all be affected in the same fashion, e.g. a nuclear decay and an atomic transition, both seeing the same effect on their rate from a given force or motion, even though the characteristic interaction strength is different.

I can't recall having occasion to work out such a problem, but you can do it. http://math.ucr.edu/home/baez/physics/Relativity/SR/acceleration.html

No. The time difference will depend on the time spent traveling at v. The shift in simultaneity occurs when she changes inertial frames; that's when the symmetry of the two observers is broken.

SR assumes flat spacetime. The expansion of space isn't covered.

When they return? There are a few different scenarios depicted in this thread, so one has to be sure to not apply this solution to the other scenarios. In the one you describe, Betty accelerates and Adam does not, so Betty's clock will be slow at her return. She shifted inertial frames during the acceleration (typically one only includes the turnaround acceleration in the simplest version of this; one can assume synchronization after Betty gets up to speed at departure and the comparison made before she changes speed upon her return) and that's when the shift in simultaneity occurs. You seem to be mixing constant c sending a signal with the time interval of a set of signals. The light may get to you at c, but the interval between two signals can still change — a simple Doppler shift shows that, even in the non-relativistic limit.

For Fermions, of course. Photons, for example, are Bosons and are quite capable of doing so.

I wouldn't be surprised if you can find examples where you can do this (my very sparse recall of Lie algebra/symmetry groups isn't helping me here) but I think the salient point is that it's not generally true. (In fact, I've seen some recent discussion of GR elsewhere that have included the concept of non-orthogonal time). But being possible and being universal aren't the same thing; e.g. you can use non-orthgonal coordinates, but it's usually useful not to. Happy to be shown wrong, though, if someone can do it rigorously

Velocity includes time in it - it's a rate. You're just moving the problem elsewhere. Time is orthogonal to spatial coordinates; as such there's no amount of fiddling you can do to have the spatial coordinates describe the time coordinate.

Dumber? Possibly. But when it comes to the media and science, I don't think there's all that far to go. Most journalists — even the science ones — simply aren't trained in science very much. Things have to get simplified for them, and then they try and explain it to others. A lot gets lost in translation.