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Quote from: mad aetherist on 15/12/2018 02:35:36Anyhow i reckon that in an elevator in free fall..(1) In free-fall in deep outer space a beam of light from a distant star entering a small hole would remain straight (& hit the far wall). This is based on this being a ballistic Newtonian bending (which cancels the bending due to free-fall).Not a local test. You're looking out of the window.
Anyhow i reckon that in an elevator in free fall..(1) In free-fall in deep outer space a beam of light from a distant star entering a small hole would remain straight (& hit the far wall). This is based on this being a ballistic Newtonian bending (which cancels the bending due to free-fall).
Quote(2) In free-fall in a gravity field (near a planet) the beam would curve (& hit the far wall). This is based on an Einsteinian bending which is twice the Newtonian.So here the observer would be able to tell whether in a gravity field based on there being a curve or not. A legit test, but both should be straight. So where do you get this "Einsteinian bending which is twice the Newtonian"?
(2) In free-fall in a gravity field (near a planet) the beam would curve (& hit the far wall). This is based on an Einsteinian bending which is twice the Newtonian.So here the observer would be able to tell whether in a gravity field based on there being a curve or not.
QuoteIf the Einsteinian bending = the Newtonian bending then the beam might be straight in both (2) &(1).But in (1) the individual photons would remain pointing in line with the beam at all times, whilst in (2) the photons would gradually yaw (in the vertical plane) & would be crabbing along the line of the beam & would be pointing on a different vertical angle to the beam especially at the end (the curved beam being their traject).I'm sorry, but the English is so poor here, I cannot parse this. No idea what 'crabbing' is, or what it would mean for a photon to 'yaw' or 'point', or for that matter what you think would cause it to do so. Photons get measured when the interact with something. Yaw means that the thing twists sideways while moving, but without changing trajectory, sort of like a car sliding sideways on the ice.
If the Einsteinian bending = the Newtonian bending then the beam might be straight in both (2) &(1).But in (1) the individual photons would remain pointing in line with the beam at all times, whilst in (2) the photons would gradually yaw (in the vertical plane) & would be crabbing along the line of the beam & would be pointing on a different vertical angle to the beam especially at the end (the curved beam being their traject).
QuoteRe yawing & pointing, there is no real need to insist on having any beam curving in some sort of vertical plane (there is no vertical in free-fall anyhow), the curving yawing pointing can be allowed to happen in any plane, doesnt really matter. I just mentioned the vertical because yawing is usually associated with the horizontal plane, but if there is any curving then the yawing & pointing will occur in the plane of the curving.No matter which plane it is. I claim any beam appears to be straight for both observers.If there is a gravity field, I suppose that defines which way is vertical even in free fall, even if the observer cannot detect it. You are free to talk about it.If the observer can determine which way is vertical with a local test, that's something the guy in space cannot do, so that would be a distinction.
Re yawing & pointing, there is no real need to insist on having any beam curving in some sort of vertical plane (there is no vertical in free-fall anyhow), the curving yawing pointing can be allowed to happen in any plane, doesnt really matter. I just mentioned the vertical because yawing is usually associated with the horizontal plane, but if there is any curving then the yawing & pointing will occur in the plane of the curving.
If u like u can shine a light beam from wall to wall inside. Possibly the same thing.
I thort that Einsteinians all agreed that the bending at the Sun is 1.75 arcsec whilst the Newtonian ballistic prediction is 0.875 arcsec, which is in effect 2:1.
But i am surprised that u consider that both should be straight, i would have thort that Einsteinians would insist that both be curved.
Yes yaw is a rudder thing. If one considers that a photon is shaped like a bullet then in (1) the bullet follows a straight traject & at all times the bullet maintains its initial "aim" or "heading", ie it points in the same direction all the way, ie in this case it points exactly along its straight traject all the way, whilst in (2) the bullet follows a straight traject but the bullet as u say slides sideways (crabs), the crabbing getting worse & worse & being at a max when it hits the wall.
If the beam is straight then if the photon-bullet is at all times in line with the beam then that indicates no gravity field -- or if the photon-bullet is crabbing-skidding then that indicates the presence of a gravity field
I think that it is ok to insist on non-local inputs. However in the case of my far-away starlight i think that that should be acceptable
Ok i had a think.
I crunched some numbers in Excel. For a 10 m wide elevator & g = 9.8 m/s/s a beam travelling at 300,000 kmps will fall 5.44 pico mm (mm^-12) measured at the far wall, & the beam angle at the wall (ie the tangent to the curve) will be 0.2235 pico arcsec (arcsec^-12). This is a simple ballistic calculation (ie as per Soldner)(ie as per Newton).
Good luck. The Institute of Naked Scientists.PS -- can we keep the nude pix u sent us.
Quote from: mad aetherist on 15/12/2018 20:49:32I think that it is ok to insist on non-local inputs. However in the case of my far-away starlight i think that that should be acceptableThen the task is trivial. No need to consider photons. The star is not accelerating with you, so just watch the star and if it seems to accelerate, it is you that is actually accelerating. Measuring the bending of light is totally unnecessary.
If the star is nearby then u could cheat in that way, but i am talking about a distant star, meaning a distant galaxy of course. Here u could cheat by using that to tell u if any rotation of the elevator (at least in one or two planes)(it couldnt tell u about all 3 planes).
One problem with this star stuff, & with much of the elevator stuff that u read, is that everyone ignores the need to keep the elevator steady, if any rotation or vibration then most bending tests would be hopeless.
Quote from: mad aetherist on 16/12/2018 02:02:21If the star is nearby then u could cheat in that way, but i am talking about a distant star, meaning a distant galaxy of course. Here u could cheat by using that to tell u if any rotation of the elevator (at least in one or two planes)(it couldnt tell u about all 3 planes).Rotation is absolute, so I don't need to look out the window to detect rotation. Rotation is about one axis, not one or more planes.A super-distant star is functionally the same as a light source bolted to the box.
QuoteOne problem with this star stuff, & with much of the elevator stuff that u read, is that everyone ignores the need to keep the elevator steady, if any rotation or vibration then most bending tests would be hopeless.You quoted Einstein's description. It was a box hanging on a rope that went off into the darkness. The guy could go outside the box and see the rope.
We can assume a reasonable lack of vibration and spin. If it spins, the guy can take steps to halt that. He's got a lab after all. Yes, that's what gyros do. You can halt the spin of Earth if you are in possession of a gyro that's up to the task.
the photons coming from the distant star will be pointing exactly along that vizible line, whereas photons coming from an internal source can be crabbing-skidding as they come out (i can explain).
But it is obvious to me that if an elevator is accelerated upwards at g (in zero gravity) then the beam of light crossing the elevator must appear (for an observer in the elevator) to have a bend downwards equal to a ballistic trajectory.
Therefore the beam will appear to go straight when the elevator is in a gravity field & when not.
To the observer the photon will appear to crab, ie skid sideways. But the photon will in fact be propagating directly ahead in its own frame, ie as if following a simple curved trajectory.
So in theory it might be possible to measure the downwards angle.[/b] However the problem is that the downwards angle of such a photon is certainly much too small to measure -- & in any case i don’t even know of any kind of test that might measure such an angle.
Quote from: mad aetherist on 16/12/2018 11:39:00But it is obvious to me that if an elevator is accelerated upwards at g (in zero gravity) then the beam of light crossing the elevator must appear (for an observer in the elevator) to have a bend downwards equal to a ballistic trajectory. Careful of things you find 'obvious', but yes in this case. Ditto for the one sitting on the surface of Earth.The straight-across observation was for the freefall case, both in and not in a gravitational field.
Quote from: mad aetherist on 16/12/2018 12:11:02Therefore the beam will appear to go straight when the elevator is in a gravity field & when not.So says the 'silly' equivalence principle, yes.
QuoteTo the observer the photon will appear to crab, ie skid sideways. But the photon will in fact be propagating directly ahead in its own frame, ie as if following a simple curved trajectory. So far you have failed to say how this can be measured. If you like, make the gravity and distance large, so the 'crabbing' is significant.
QuoteSo in theory it might be possible to measure the downwards angle.[/b] However the problem is that the downwards angle of such a photon is certainly much too small to measure -- & in any case i don’t even know of any kind of test that might measure such an angle.It would I suppose help if there was such a thing.
I do believe in relativity, neo Lorentz relativity, not Einsteinian SR & GR relativity (altho in many cases they give the same answer).
But when Brown measures the angle of the two pendulums (wts on threads) then in a gravity field if he uses a measuring rod horizontally then the length of the rod will not be affected by its height from the floor because the rod is being held perpendicularly to the line of action of the field, Einsteinians & aetherists agree.
Quote from: HalcSo says the 'silly' equivalence principle, yes.I think that there are a few 'the' equivalence principles.The primary one is i think the law of the equivalence of inert mass & gravity mass (as per Einstein's chest thort-X).The next one is say the weak equivalence principle, that all things fall at the same speed.The next one is say that all experiments will give the same equivalent result in any-every reference frame.
So says the 'silly' equivalence principle, yes.
Modern science seems to have ignored photons. There is little official info re how long or wide etc a photon is or isnt. Are photons dead straight.