True, but it implies there is some truth to the story. I’m actually intrigued as to exactly what happened. Though that would require getting access to that obscure periodical that was listed as a cite in that article.
In 1988, I was working on the GPS system for the V22 Osprey and the subject of relativity came up once. IIRC, the clocks on our local system ran at XX.000000000000000000003 MHz (not the real numbers, I’ve forgotten the actual frequency) to compensate for the effects of relativity whereas the satellite was xmitting exactly XX MHz… I guess they figured it was a lot easier to fine tune a diode here on Earth rather than at 20,000km.
So far as I know, GPS is the only consumer product for which GR is relevant, but SR shows up all over the place-- It’s one of those things that’s so ubiquitous that most folks don’t realize they ever deal with it at all. Just for starters, magnetism is an inherently relativistic phenomenon.
And griffin1977, none of this has any connection to quantum mechanics. Quantum mechanics is a completely different field from relativity, and in fact QM and GR are fundamentally incompatible.
Which is why I claimed it was BS. Relativity and the nature of relativistic effects has been settled science since the very early 1900’s. Top echelon military typically have fairly comprehensive educations, a fair degree of technical acumen, and are generally pretty intelligent men. Painting them as doubting the “truths” of relativity is ludicrous.
You might say that, but a professor of Physics who was closely involved in the process says otherwise.
… about some unspecified person or persons with some unspecified connection to this.
One thing I’ve noticed about both History and Discovery (from seeing topics I’m familiar with) is that a single comment or observation, made by someone involved somewhere along the way, can get easily stated as though it were factual (including no attribution). It usually seems to come into play when a story needs to be made more exciting/dramatic.
True, and its not impossible that this is just some joke or urban myth that was repeated until it was treated as fact.
But on the other hand that someone involved in the project doubted it was stated as a fact in a article by a leading physicist in publication from the Max Plank Institute, this gives it quite a bit of credence in my view.
True, but to be mention at all, it must have been someone whose opinion mattered when it came to GPS signal timing.
I’m not just referring to jokes or urban myths, however. Imagine the engineers are sitting around the table with the brass and some Captain says suspiciously “are you SURE about that? That makes no sense to me!” Eventually through word of mouth that can become
I’m not saying that’s the case here at all (hard to know without seeing the article), but I’ve become suspicious of the research rigor of those two channels when it comes to dramatic moments.
Atomic bombs would work whether or not GR was true.
The OP is malarkey, but it is true that the pseudo-scientific beliefs of the military have played a role in the development of weapons. The trouble is that they believe too much, not too little. After the Manhattan Project many generals seem to have come to think that with enough money and scientists, anything could be done. They wanted to spy on the Russkies using psychic powers, and develop “truth serums” for use on POWs or captured spies. Richard Feynman once claimed that a general asked him if a tank could be designed to use dirt for fuel.
While its all very reassuring to know that all of those experts are on the job,didn’t a space probe (for Mars I think ) catastophically malfunction not that many years ago because the drawings were in metric measures on one coast, but were assembled in imperial on the other ?
(Or vice versa) .
Just recalling from memory here but could probably get a cite if demanded.
Pretty garbled about the Mars mission. Feet versus metres for the approach distance to Mars.
Something about GR that strikes me. It isn’t true to say that GR is some thing that has been a settled issue for a century. The first paper was published in 1916. These questions about the GPS system come from the mid to early 70’s - so we are really talking about 60 years. Still a long time. However if you look at the experimental verification of GR, the results only really started to accumulate in the 70’s. Before that GR was much more theory, and little validation - you had Eddington’s famous eclipse photos, the perihelion of mercury, and gravitational redshifts. The first flown clocks experiment was 1971 (Hafele–Keating experiment) with a better accuracy followup in 1976. This is in the thick of defining the parameters of GPS. It is all well and good to invoke the hallowed name of Einstein, but at the time these questions were being raised, GR wasn’t the fantastically validated theory that we see now. Gravitational lensing was first seen in the 70’s, as were gravitational waves in binary pulsars. Frame dragging is only now just validated via Gravity Probe B. Sure, most physicists expected that the theory would be so validated, but in the early 70’s it hadn’t been, especially not with flying clocks, and I suspect a few people were hoping for a trip to Stockholm if they found a hole in it.
The other issue I perceive, is that GR is a difficult subject as it requires a lot of care in framing the questions and deriving the results. Look at the current question about the neutrino flight times. The current GPS systems provide wonderful validation of GR, but it is also clear that the early satelites were built with enough flexibility in their design that if there were unexpected anomolies in the calculated effects of GR they would be able to cope.
The mars probe fiasco was a unit thing but the units were not distance. It was either the amount of thrust or the integrated amount of thrust IIRC. And the mix up was such that WAY more thrust was applied than was needed. So rather than slowing down just enough to enter orbit around mars, it was slowed down enough that it impacted the surface (not sure if it just burned up in the atmosphere though).
That event created one of my favorite smarty pants new terms. Lithobraking.
Sorry mate, I’m chinstrapped, no sleep for a fair while so not working at optimum.
OK, I’m going to have to remember to use that one.
Sorry about my previous, I was very much suffering from a lack of sleep so didn’t make my point well.
There seems to be a lot of posts here determined to try and spare the blushes of those responsible for the project, who may or may not have been guilty of the lapse that B.C. referred to.
One of their major arguments is a circular one.
In that the project was highly complex and had a high level of scientific and technological difficulty to implement.
Therefore you obviously couldn’t entrust such a project to those of average, let alone mediocre scientific ability, or for that matter intelligence.
People of that high level of knowledge and ability won’t make significant errors or omissions.
Ergo it never happened.
Thats the argument.
My point about the Mars probe was that people of that level ability DO make silly and/ or serious errors.
There also seems to be a recurring theme here based on the “Lawnmower” argument.
That is, I returned your L.M last week, and anyway you never lent me your L.M., and anyway it was broken.
ie. Yes they did take G.R. into the equation, but anyway its effect was neglible and anyway some aspects of the theory aren’t fully proven.
Plus my dog ate the drawings.
Personally, while I have no dog in this fight, I’m inclined to believe a proffessor of Oxford.
who is also a member of the Royal Society (and so according to previous posts couldn’t be mistaken about this) , and who more importantly has no axe to grind about the subject, and no career to be harmed.
If the event actually did happen then it should not be swept under the carpet, if only to prevent future recurrences in other projects.
Recurrences that have the potential to cost human lives in some circumstances or be very,very expensive .
I take it you mean the word and not the actual technique 
This is the part where your analogy breaks down. Relativistic effects were anticipated as part of a body of science that had been around for decades. The story has the military heads of project not doubting the operational impact of relativistic effects but doubting whether they exist at all. Military brass involved with or heading technical projects tend to have a fairly up to date college educations, some even have advanced degrees in relevant technical areas.
My uncle was a rear Admiral with an advanced degree in mathematics who oversaw and was involved with the specification and implementation of many communication projects for the Navy. It’s comforting to have cartoon like stories about ignorant, bombastic military brass but the reality is somewhat different at least for the US military.
I tend to consider the GPS system as a large engineering project. It had a military role, a secondary civilian one, but ultimately run as a very significant and expensive engineering project. Engineers are conservative. In the space game very very conservative. If I was heading up a large project like this, and GR was a critical aspect of the design, which it clearly is, I would want to know that I had all bases covered in my design. Like I wrote earlier - when the design was being done they had only just done the first ever flown clocks experiment. Sure it agreed with GR’s predictions, but if I were sitting on a few billions dollars of government project, and there was even a whiff of doubt from some quarters about the general applicability or correct derivation of all the implications of GR, I would want to hear a really good story about the design having enough flexibility in it to cope with unexpected differences between the expected physics and what we might see. It is easy with 40 years hindsight, and lots of new verification of GR to say that such caution was misguided. But also wrong to do so. I would suspect that you would have been hard pressed to find a physicist that was prepared to absolutely guarantee that GR was the be all and end all of expected effects before they flew the first constellation. The history of physics has shown that such hubris is often the precursor to new physics being discovered. It is also worth pointing out that it was already well understood that GR is not complete. As we still know, it is fundamentally incompatible with QM. That isn’t something that is going to bring comfort to a project manager. As an engineering manager, I would be derelict in discharging my duty if I didn’t ensure that the project had enough risk mitigation in its design to cope with unlikely, but not ruled out issues. That the design did have just such flexibility is evidence of very sound management. Indeed much sounder management that simply going with the majority expectation.