Is Relativity 100% proven to all professional scientists satisfaction?

[Nicholas Kang]

 

I'm narrowing the source of the problem when someone's GPS unit gives them a bad indication. It's not the satellite, it's not relativity. "GPS doesn't work" is an issue of some sort with the receiver you possess.

So, what`s wrong with the receiver?

[Strange]

Wildly different routes?

 

Calculating optimum routes is one of those things we can do pretty well just by glancing at a map. But is a very hard problem for computers (it might be NP-complete).

 

 

GPS is a "computer", isn't it? It has to be programmed to do the job the right way. And the programming is more than just installing a map? Yes?

 

Yep. Just a processor with a bit of specialised hardware and software (at several layers: calculate position from satellite data; transfer that to map position; work out best route; tell driver what to do; ...) The bugs can appear anywhere in those things. There are also things like radiation causing random bit changes in memory, which can make the system go wrong. But it is usually human error.

[Delta1212]

Oops! I was pronouncing it right. Guess I didn't check carefully. Haste made waste. Thanks.

 

GPS. At least it isn't as much of a mystery to me as some things. So much new has sprung up in the last forty/fifty years. Hard to keep up. Steganography.

 

What you call "meta information" would definitely be extra information that someone would need to program in, wouldn't it? That's what I was asking about earlier. Isn't some of this a matter of programming the GPS correctly. I recently read about a steep road that goes up a small mountain into a town in Wales. The road is barely wide enough for one-way traffic. The natives all know about it and take care but GPS does not give that information. There had been a few bad accidents caused by uninformed drivers relying on their GPS system. So, yes, "meta information" bears watching. Do the better systems have such information programmed in? It would take constant updating. "Road construction on route 77"?

 

Wildly different routes? Maybe some are measuring distance in time instead of miles or kilometers? I know you know the many people who now measure distance in time. Ask them how far something is and they'll say "Oh, about five minutes" or "Just two hours". Now, there's theory of relativity that I understand.

 

Anyway, on that point - get the math right? Maybe I am wrong but I'm still taking most of those errors back to a human who has to do some programming. GPS is a "computer", isn't it? It has to be programmed to do the job the right way. And the programming is more than just installing a map? Yes?

Yes. Most of the good ones have their own proprietary map that includes a lot of metadata about all of the streets. Then you need good path finding algorithms that make effective use of all that data. A few, like google maps (especially after buying up and incorporating Waze), crowd source real time data so that you can see where traffic is building up on a route, where there is an accident or construction and the probable time a given route will take in light of those things, with the option to choose among routes or even dynamically rerouting you in the middle of your trip if the path you're on has a traffic build up that makes an alternative route better.

 

How to weight information like that, make those decisions and even things like finding the shortest route vs finding a slightly longer but more easily navigable route are all down to the programming that the receiver contains. Relativity is required to obtain information about your position on Earth, everything the GPS does after that is down to human engineering and programming, and that opens a lot of doors to excel or crash and burn (hopefully not literally).

[swansont]

So, what`s wrong with the receiver?

 

Mainly an issue of quality of the maps, metadata and algorithms as we've been discussing in the thread.

[cosnut]

Here is some thoughts for contemplating. First of all, S.R. is half proven - when a particle or clock is accelerated to a new velocity and then coasts at the new velocity which is different than the velocity of clocks on earth, the clock which has been raised to a higher velocity always runs slow. But there are very few measurements made by clocks aboard hi speed muons and pions accelerated in the laboratory to verify that from the perspective of the high speed clock the clock on earth runs slow. Same sort of situation arises with regard to measuring the speed of light - the round trip speed of light is always measured to be constant, but its difficult to find good experimental evidence for the constancy of the one way velocity of light. The M & M experiments measured the over and back velocity - Einstein extended the interpreted of that result in his 1905 paper to explain why the traveling clock that leaves earth and travels for a long time and returns, will have accumulated less time. But in actuality, the clock never really needs to return. It could stop on a distant planet and when it did, its clock would have accumulated less time that any clock in the earth frame including those spaced along the way that were not moving wrt earth. In 1918 Einstein realized that SR as originally framed, could not account for the effect as originally presented - he introduced a G field and worked the problem, but upon a careful reading, it also raises problems. Max Born in his book flat out states that the twin problem cannot be solved using SR, as do a number of other authors. Any time the experiment is symmetrical with respect to the motion (i.e., two trains passing each other at hi speed in space) the clocks in the train taken to be at rest will appear to have accumulated more time than the clock aboard the other train - but since there is no way this can be real for both trains, when the clocks are brought together they must read the same. Real time dilation can only occur when one clock is raised to a different state - it is not the acceleration that brings this about, that the two frames are no longer identical. This is the situation with the pion that travels in the lab or the spaceship that goes to Altair - in both cases, the traveling clock is given an initial boost but for most of the journey the speed is constant - nonetheless the difference in the total amount of accumulated time continues to grow - all the time it is boosted clock is moving at constant velocity

[Strange]

First of all, S.R. is half proven

 

It is not even half-proven. No scientific theory is ever proved. They are just not proven wrong.

 

Same sort of situation arises with regard to measuring the speed of light - the round trip speed of light is always measured to be constant, but its difficult to find good experimental evidence for the constancy of the one way velocity of light.

 

Not just difficult, but impossible. But if it were not the case, then the theory would not work.

 

The M & M experiments measured the over and back velocity - Einstein extended the interpreted of that result in his 1905 paper to explain why the traveling clock that leaves earth and travels for a long time and returns, will have accumulated less time.

 

That is a very garbled view of history. It is not clear if Einstein had heard if the MM experiment but it certainly played no part in the development of special relativity.

 

In 1918 Einstein realized that SR as originally framed, could not account for the effect as originally presented

 

Huh? The twin paradox can be fully explained using special relativity.

 

he introduced a G field

 

Really? What is a "G field"?

 

Max Born in his book flat out states that the twin problem cannot be solved using SR, as do a number of other authors.

 

Then those authors are wrong. Perhaps you could provide some references?

 

Any time the experiment is symmetrical with respect to the motion

 

The twin paradox isn't symmetrical.

[imatfaal]

Then those authors are wrong. Perhaps you could provide some references?

 

 

The twin paradox isn't symmetrical.

 

Max Born was working on the problem / and the clock paradox whilst GR was being developed and before even SR was fully formed/accpeted.

 

If I remember my history correctly both Einstein and Pauli beleived that GR was necessary to completely deal with the twin paradox. SR can encompass the solution when additional ideas that are not essential or part of SR are invoked (to do with the absolute nature of acceleration) - but for a theory that, in and of itself, contains the solution you must look to GR. I will repeat this is history to me - not maths or science as I lack the full understanding to defend either point of view.

[xyzt]

 

Max Born was working on the problem / and the clock paradox whilst GR was being developed and before even SR was fully formed/accpeted.

 

If I remember my history correctly both Einstein and Pauli beleived that GR was necessary to completely deal with the twin paradox. SR can encompass the solution when additional ideas that are not essential or part of SR are invoked (to do with the absolute nature of acceleration) - but for a theory that, in and of itself, contains the solution you must look to GR. I will repeat this is history to me - not maths or science as I lack the full understanding to defend either point of view.

This is not correct, here is the complete mathematical solution that I wrote for wiki. It is done using SR exclusively.

[cosnut]

In response to post 81:

 

Time dilation is proven. But it is only proven for one of the relatively moving objects. The one that got accelerated. That is clock that is in a different state.

 

Proving the one way speed of light is only impossible when you are using the speed of light to make the measurements.

 

Do you really believe that Einstein was unaware of the M & M experiments - his fascination with light was an obsession since his early childhood. The M and M experiments were well publicized - even Einstein's biographers have a problem explaining his pretense of vaguely hearing something about it -

 

What is a G field -... read the 1918 paper.

 

References: Einstein's theory of Relativity, by Max Born, 1962 and 1965, Dover at page 356 - "the clock paradox is due to a false application of the Special theory of Relativity, namely to a case in which the methods of the general theory should be applied." also see page 261 and 262.

For what its worth, the introduction of a "g" field, is in my opinion, incorrect and it obscures the real reason for the time dilation.

 

The twin paradox is not symmetrical - I didn't say it was - but two space ships in free space passing each other at relative velocity v is symmetrical since each is free to consider himself as not moving (the inertial frame) and each will measure the other clock as slow according to relativity. This is an example of apparent time dilation - real time dilation can involve a one way trip or a round trip - but it always involves a change in velocity - and the experiments confirm the clock that got the boost runs slower. There may be one experimental exception to that, but I won't go into it

[Strange]

Do you really believe that Einstein was unaware of the M & M experiments

 

I didn't say he was.

 

 

What is a G field -... read the 1918 paper.

 

Oh well, if you can't be bothered to explain what you are talking about, I can't be bothered to discuss it.

[xyzt]

In response to post 81:

 

Time dilation is proven. But it is only proven for one of the relatively moving objects. The one that got accelerated. That is clock that is in a different state.

 

You seem deeply confused, the twins paradox is not about differences in time dilation (there aren't any) but about differences in total elapsed time. And the clocks, contrary to your misconceptions, are not affected by acceleration. Google "the clock hypothesis".

[md65536]

real time dilation can involve a one way trip or a round trip - but it always involves a change in velocity

http://en.wikipedia.org/wiki/Time_dilation#Muon_lifetimeis a counter example I think.

 

A particle traveling through the atmosphere at relativistic speeds will be time-dilated according to Earth observers (and vice versa). This is true for inertial particles traveling through space, passing through the Earth unaccelerated.