Existence

From http://www.phys.lsu.edu/mog/mog9/node9.html:

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At the time of launch of the first NTS-2 satellite (June 1977), which contained the first Cesium clock to be placed in orbit, there were some who doubted that relativistic effects were real. A frequency synthesizer was built into the satellite clock system so that after launch, if in fact the rate of the clock in its final orbit was that predicted by GR, then the synthesizer could be turned on bringing the clock to the coordinate rate necessary for operation. The atomic clock was first operated for about 20 days to measure its clock rate before turning on the synthesizer. The frequency measured during that interval was 442.5 parts in 10^12 faster than clocks on the ground; if left uncorrected this would have resulted in timing errors of about 38,000 nanoseconds per day. The difference between predicted and measured values of the frequency shift was only 3.97 parts in 10^12, well within the accuracy capabilities of the orbiting clock. This then gave about a 1% validation of the combined motional and gravitational shifts for a clock at 4.2 earth radii.

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Actually the way I first heard it, there was a third camp of engineers who thought that the effect was in the opposite direction, so the clock module had three settings, with a +, 0 and - correction.From the same source, it seems that it is technically incorrect to say that GPS provides a continuous demonstration of gr:

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At present one cannot easily perform tests of relativity with the system because the SV clocks are actively steered to be within 1 microsecond of Universal Coordinated Time (USNO).

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Edited by fizz57102, : No reason given.

Hi F&L,
As others have pointed out, you've been a bit unfair to me Having done the maths (albeit a long time ago - I'm in a different branch of fizzix now) it's a bit difficult for me not to accept its validity - a scientific theory isn't something you "believe" in after all.And that's the problem with ICANT -hecant do the maths - through laziness, ignorance or sheer bloody-mindedness for all I know - and so doesn't see the inevitability of the conclusions. His only reply is his usual word salad which can be used to "prove" anything - after all, that's how it works in the field he considers to be his speciality!

Can everyone stop using this message subtitle please?On reflection, ICANT certainly is one of a kind. I've dealt with peddlers of crackpot ideas before, but have to admit that I've never come across anyone quite like him. He is a joy to watch in action - from a discreet distance, of course.

Hi ICANT,
Permit me to butt in again before departing for the depths once more... The answer to your conundrum should be glaringly obvious if you had ever cared to read anything about relativity. You see, time dilation (terrible word that) does not stand alone, there is also length contraction (another bad choice of word). If you're travelling at c/2, the distance you travel in your frame of reference is also reduced, coincidentally by the same amount that the time is "dilated" in that frame.So the opening statement of the quote is WRONG - and of course, the rest then just falls apart.If you execute your turn-around at a pre-determined point one light-year from the Earth (as measured FROM EARTH), then you'd arrive earlier than you expect - your odometer would read 0.87 light years and your dash clock only 1.75 years.... on your return, you'd only have been travelling for 3.5 years, although 4 years would have elapsed on Earth. And if you'd planted a flag at the turn-around point, when you return to Earth you'd see it's really 1 light year away after all!Oh, and before you get clever with me, if you'd gone on for the whole 2 years so that your odometer read 1.0 ly before turning, then 4.6 years would have elapsed on Earth and measurements would show that you've planted the flag 1.15 light years away.Hard to twist your mind around, but no contradiction, no paradox. As I've said earlier it's mathematically INEVITABLE if the speed of light is to remain constant in all inertial frames - only you won't do the maths, will you? And it's been experimentally proven - as others have already told you, you really should read up about the cosmic-ray muon problem, which you've also been avoiding.And I'll leave you with a quotation, from worthier lips than mine - there are none so blind as those who WILL NOT see.

Hi ICANT,
I note that you've responded in your (thankfully) inimitable style. Your post is so full of errors, irrelevancies and misunderstandings that one doesn't know where to start responding. So rather than a line-by-line rebuttal, which would only lead to an ever-lengthening ping-pong between us, I'm going to focus on just one point. I won't forget the others, though, but we need to get some things clear first.You tell me: but you tell crashfrog: Can you please make up your mind on this? Once you've decided which position to take, we can proceed.Edited by fizz57102, : removed parting shot in the hope ICANT will focus on the question.Edited by fizz57102, : Complete rewrite to prevent another possible weasel-out