Is the Special theory of Relativity wrong?

[MeerkatinBKK]

GPS is a GR correction I believe stacey, is it not correcting for time dilation induced by the weaker field experienced at orbit?

spoken like a true physicist....nice one!

It's a bit of both.

GPS sats are affected by both SR due to their speed (slowing their clocks as it seems to us), and GR because of their distance from the Earth (speeding them up). The GR effect outweighs the SR one though.

Nick

[vhbelvadi]

GPS is a GR correction I believe stacey, is it not correcting for time dilation induced by the weaker field experienced at orbit?

spoken like a true physicist....nice one!

It's a bit of both.

GPS sats are affected by both SR due to their speed (slowing their clocks as it seems to us), and GR because of their distance from the Earth (speeding them up). The GR effect outweighs the SR one though.

Nick

I'm lost!

Can ANYONE tell me what this GPS and GR stuff is, you're talking about?

[Andrew*]

I'm lost!

Can ANYONE tell me what this GPS and GR stuff is, you're talking about?

GPS (Global positioning satellite) is a device which gives your location on earth.

GR is general relativity.

SR is special relativity.

I agree - acronyms can get confusing! Oh, and then there's GR...:confused:

[MeerkatinBKK]

I'm lost!

Can ANYONE tell me what this GPS and GR stuff is, you're talking about?

GPS - Global Positioning System (ie the satellites that talk to the SatNav in your car)

GR - (Theory of) General Relativity

SR - (Theory of) Special Relativity

At the heart of each GPS satellite is a highly accurate atomic clock.

Special Relativity however tells us that due to the high speeds the satellite orbits at, the on-board clock will run slightly slower than an equivalent clock on the Earth.

General Relativity on the other hand tells us that time will run more quickly the further a body is from a large centre of mass (the Earth in this case) - a phenomenom known as gravitational time dilation.

Thus the clocks onboard a GPS satellite are being both slowed down and speeded up (in relation to us on the Earth) and need to be corrected. The GR component outweighs the SR component, so the GPS clocks are set to run slightly slower than a clock on Earth.

It's quite interesting as these time corrections are a good example of empirical evidence that Einstein's theories were correct. Check out the wiki links above for a bit (erm a lot!) more detail.

Nick

[vhbelvadi]

Thanks Andrew, Nick.

Turns out I actually knew the full-form of GPS, but I didn't recognise it. But I didn't know that General Relativity and Special Relativity were written as GR and SR for short.

The info. you provided was helpful, too, Nick. And, as for the wiki links, I actually learnt the Relativity theories from there, in my eighth grade.

Thanks again.

[SC-Pulsar]

Indeed Paul, thanks for keeping me right, yes the time dialtion taken into account is due to the spacetime having less curvature, so GR.

Thats what a whole day of studying GR does to you.

But the fact that GR is somewhat postulated on SR goes to show Einstein was clearly on the right tracks!

Stacey

[NickH]

Thanks Andrew, Nick.

The info. you provided was helpful, too, Nick. And, as for the wiki links, I actually learnt the Relativity theories from there, in my eighth grade.

Thanks again.

How old are you then?

wow...

[vhbelvadi]

How old are you then?

wow...

I turned 16 last month.

And, speaking of GR, if anyone has read Dr.Sagan's Cosmos or has come across the flatland experiment anywhere (like in Bill Bryson's A Short History of Nearly Everything) can you think of any such thought-experiment which we can relate, to make someone familiar with 4 dimensions, understand the 11 dimensions from the string theory? I have a friend who needs some help.

Or, should I have not posted this message here?

[narrowbandpaul]

the books I would recommend for string theory are both by Brian Greene.

his first one was more based on string theory.....its called The Elegant Universe.

he talks of the other 7 dimensions there, and calabi yau spaces, and a whole host of wonderful mathematical concepts.

thats what string theory is.....a whole load of really really difficult math, which hopefully represents the true nature of reality.

if you really want to learn string theory and contribute, I suggest you like math!! :-)

but brian greenes books are very good. i recommend them.

I dont think there is any way to visualise another dimension, let alone another 7.....

paul

[narrowbandpaul]

you are clearly interested in physics.astronomy/cosmology, do you plan to study such things at university? are you UK based?

[vhbelvadi]

the books I would recommend for string theory are both by Brian Greene.

his first one was more based on string theory.....its called The Elegant Universe.

he talks of the other 7 dimensions there, and calabi yau spaces, and a whole host of wonderful mathematical concepts.

thats what string theory is.....a whole load of really really difficult math, which hopefully represents the true nature of reality.

if you really want to learn string theory and contribute, I suggest you like math!! :-)

but brian greenes books are very good. i recommend them.

I dont think there is any way to visualise another dimension, let alone another 7.....

paul

Thanks a million, Paul!

[SC-Pulsar]

Paul stop trying to recruit people for Glasgow!!

[narrowbandpaul]

we should encourage people to come to glasgow, no?

we both know where we are in the league tables........

via veritas vita:icon_salut:

paul

[vhbelvadi]

we should encourage people to come to glasgow, no?

we both know where we are in the league tables........

via veritas vita:icon_salut:

paul

Heated Glasgow talk! Interesting...

[SC-Pulsar]

Ha, not heated.

We are both at Glasgow, Paul's just jealous because im way cooler than him!

Stacey

[Macavity]

I dunno. Even as an ex-particle physicist, I still share circumspection re. NEGATING such stuff. But worse still, I feel unqualified to SAY! As a fellow student (A Yorkshire Lass!) once said of PC102: I don't get all this "rod stoof, wi' clocks on"! She was NOT alone, I suspect?

[ncjunk]

Intresting thread...

For me the Theory of relativity has been proved to date (just look at gravitational lensing and the pics from hubble) but will probably have some flaws along the same lines as Newtons.

Newtons laws, for instance, are good enough when v is less than c. So for most of us common folk Newton still explains things well enough and Einstein's theory won´t even get a look in. But as the velocity gets closer to the speed of light then things start to change.

Check this link out it is quite interesting.

Theory: Special Relativity (SLAC VVC)

I am quite looking forward to seeing if they manage to find the Higgs Bosen when CERN is finally up and running or if they just manage to solve some things and a whole bucket full of new questions.

Anyhoo the bloke who wrote the initial article just doesn´t understand the theory it is as simple as that.

My answer to the question would be it is correct to current knowledge but I am sure, like newtons, some new information will come along that will require it to be tweaked a little bit.

Neil C

[vhbelvadi]

Check this link out it is quite interesting.

Theory: Special Relativity (SLAC VVC)

Neil C

Nice link.

Thanks Neil.

[part timer]

I suppose it comes down to what you call wrong.

Relativity is spectacularly successful in accounting for many observations. It is clear that nobody can disprove the theory yet!

There are however problems. The lack of 'quantum' relativity despite pretty intensive study by a lot of people is the main one. Also it's wise to remember that measurements of this nature are out of the sphere of what you might call 'human experience'. All experiments and observations of relativistic phenomena are subject to interpretation. This is why no two physicists believe exactly the same theory!

The problems of course mean that we have two bizarre sets of modern Physics theory's (quantum mechanics and relativity) which are both seemingly unreasonable (that's the only thing all students of Physics agree with!) and yet successful. The two are not good bedfellows and this is an indication, to me at least, that they are both right, but in the wrong way, somehow. I think that ultimately the next big leap in Physics will come when someone thinks of a different starting perspective (a bit like the difference between Newtons 'force' and Einstein's 'effect' views of Gravity but on a universal scale).

For what it's worth I think that, at this stage, cosmology is a rather hopeless subject. The current insistence on mysterious entity's and energy's in vacuum which require ever more complex explanations being the biggest sign, in my opinion that it would be better to start a fresh and review the basics, stopping up the gaps in our knowledge along the way.

Oh and don't get me started on string theory!

[ncjunk]

How about getting you started on unification of theories and supersymmetry?

Every trendy particle needs spin, colour and flavour!

The fact that quantum mechanics and relativity are not good bed fellows just goes to show we have a lot to learn.

Like you I feel uncomfortable at the trend to jump on the mysterious entity´s, energies and dark matter bandwagon, just because everyone else is doing it doesn´t make it big or clever.

I love it when someone comes up with something which fits very nicely indeed but can´t be measured so we end up having to look for tell tale signs that could indicate it´s presence and unluckly manage to use a completely unrelated phenomenon to justify something that does not exist.

But then we have been doing this type of thing for centuries it is just that we tend to think we are smarter than all those old buggers from 600AD.

We invented the digital watch and velcro we know everything!

Neil C

[NickH]

Spot on Part Timer...

Wrong is only relative to the sphere you are looking at...at our current bounds (and thus for all current scenarios) it pretty much works (okay, dark energy de da de da....).

GUT and the next leap will hopefully take us to another level..

[Phil Fargaze]

I couldn`t have put it better myself Part Timer. While we are at it, does The Big Bang come under Relativity or Quantum? Because I think there are cracks beginning to show in that theory.

[acey]

Evidence for special relativity is stronger than evidence that people walked on the moon. And I believe that people walked on the moon.

[part timer]

How about getting you started on unification of theories and supersymmetry?

ARRRRRRG! Hold me back!

Actually, I don't mind people having a go at these things if they want an intellectual challenge. I take issue however, with those who insist on referring to these things as 'discovery's'. This implicitly implies that what they are stating is fact when the words 'intensely theoretical' would be more accurate.

When it comes to the big bang, I am a previous believer who just can't come to terms with the theory as presented since the late seventies. I'm afraid inflation was the point at which the mainstream and I parted company. There are so many holes in the big bang that I can't even consider it as even remotely viable.

many seem to forget that there was a very good reason for the lack of belief in the Copernican universe. It was useless for predicting planetary positions, whereas the Ptolomaic system was spot on. We now realise that this is due to the fact that Copernicus didn't think of elliptical orbits. The point is though, that the ridiculously complex epicycle theory had been refined and 'improved' in ever more complex ways to 'predict' observations for hundreds of years. It gave darn near perfect predictions. The only thing wrong with it of course was that it was nonsense!

This is the big bang today. Forced into ever more extreme responses to suit observations.

None of this means there wasn't a big bang of course, just that the theory constructed to account for it is not true.

I think part of the problem is that Modern Physics is viewed by many (including at least one of my old lecturers) as explaining nature. In fact it explains no more than Classical Physics in the sense that they are both purely DESCRIPTIVE. Modern Physics describes nature down to very small scales and relativity explains one force (gravity), but the essentials are as yet completely unanswered.

For example, what is it that makes charges repel or attract? What is a force?

This means we can not expect to understand the fundamental processes of nature yet. Somebody once told me that Physics should only be concerned with what's useful. At the time I thought he was a dull old experimenter. Now I think I know what he meant. We learn a bit at a time with many false starts, but practical Physics which can be put into use and refined teaches us the most. In the end we will understand the really fundamental things but that won't be for some time.

[Phil Fargaze]

Thank you for saying what you did about inflation part timer.