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For anyone wanting to gain a basic understanding of general relativity I can highly recommend Brian Cox's new book "Why does e=mc^2?". I went to see his talk at the edinburgh science festival that was promoting his book and I can honestly say that I have never had GR so well explained to the point where I was walking out saying "of course!".

I havn't quite finished the book but it is much like the talk it takes everything quite slowly and explains the maths one step at a time in a really clear way. Well worth the read.

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Is it a known fact that this speed is universal under any conditions?

Absolutely not, light slows down when passing through glass, that's how lenses work.

Time dilation in strong gravitational fields is resoponsible for "gravitational lensing", as predicted by General Relativity.

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Absolutely not, light slows down when passing through glass, that's how lenses work.

Time dilation in strong gravitational fields is resoponsible for "gravitational lensing", as predicted by General Relativity.

OK, I get this.

So light can be slowed down or bent.

But, is there even the tinyest possibility that light could travel faster?, if given the right conditions somewhere in the universe.

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According to Einstein no. The light speed in vacuum is the absolute maximum.

Well, I hope that at sometime in the future, he will be proven wrong on that point. History is abundant in theories that were fact in their time, only to be proven wrong at a later date.

After all, we all know that the earth is flat and is at the very centre of the universe, "Dont we".

And we all know what will happen if we ever go faster than the speed of sound "Dont we".

Get my point?.

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Maybe so, that's definitely a possibility but, to my knowledge (which isn't much !!) all experiments now seam to corroborate that idea and it's the basic pillar of the entire relativity theory. If that's proved wrong the Theory either evolves or is left behind and forgotten.

I mean, if light speed wasn't limited, and added up, then Newton would be right in the 1st time. Time only needs to be perceived differently, for observers moving at different speeds, because there is a speed limit on the universe, otherwise time could remain constant for all observers, as Newton had it and it would be the speed that would add up indefinitely.

PS-> Feel free to disagree, I'm just an interested reader, my real knowledge on physics ended at high school level with Newton and after I just learned basic, over simplified, quantum mechanics applied to semi conductors (I mean simplified as in punch the values on the calculator and let it work... ;)).

Edited by pvaz
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Maybe so, that's definitely a possibility but, to my knowledge (which isn't much !!) all experiments now seam to corroborate that idea and it's the basic pillar of the entire relativity theory. If that's proved wrong the Theory either evolves or is left behind and forgotten.

I mean, if light speed wasn't limited, and added up, then Newton would be right in the 1st time. Time only needs to be perceived differently, for observers moving at different speeds, because there is a speed limit on the universe, otherwise time could remain constant for all observers, as Newton had it and it would be the speed that would add up indefinitely.

PS-> Feel free to disagree, I'm just an interested reader, my real knowledge on physics ended at high school level with Newton and after I just learned basic, over simplified, quantum mechanics applied to semi conductors (I mean simplified as in punch the values on the calculator and let it work... ;)).

No, I'm not dissagreeing with your summing up of the known facts.

I am just asking because firstly i know absolutely nothing about this subject, and secondly that it just brought up some questions in my limited brain. Thanks for your answers, they are much appreciated.

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'Well, I hope that at sometime in the future, he will be proven wrong on that point. History is abundant in theories that were fact in their time, only to be proven wrong at a later date.'

Well Ray, i'm inclined to say, No it isn't! Bear with me. There has never ever been a scientific flat earth theory. The ancients were well aware that the earth was spherical; you could see its shadow on the moon during a lunar ecliplse, you could see southern stars rise as you sailed south... You will sometimes read that Columbus was amazed to have sailed around the world. Pure historical nonsense. He wasn't. (I'm sure one could find Flat Earthers banging on in pseudo-scientific terms but peer review is a part of science and slings 'em out!)

But of course, yes, there are theories that have lived and died. But historians of science often argue that what happens more often is that theories are 'generalized' rather than scrapped and replaced by all-new ones. Newton was right in 'local circumstances'. (No high speeds, no huge masses.) It never worked for 'the anomolous perihelion of Mercury' which was the one planet in a Newton-busting gravitational field (being so close to the Sun's extreme mass.) Einstein generalized the theory to include any mass and any speed.

Nor do real scientists claim that their theories are 'fact.' The media try to present them as if they did so but if you read the big hitters of science in their own words they do not talk in these terms at all. They talk in terms of models, of our 'best theories'. This is increasingly the case, by the way. Certainty is dead. It was probably quantum theory that killed it once and for all.

If you look at the history of Darwinism it has (interestingly!) evolved but it has certainly not been scrapped. It has been refined.

So, in a nutshell, history is not as full of scrapped theories as you might think. Yes, they are there but so are generalizations and refinements. And no, the great scientists do not claim to deal in facts. Leave that to politicains and ... no, I'd better not mention religious leaders!!

Science is so important in our lives that I for one do my best to understand it, though my background is not in science at all.

Olly

Edited by ollypenrice
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'Well, I hope that at sometime in the future, he will be proven wrong on that point. History is abundant in theories that were fact in their time, only to be proven wrong at a later date.'

Well Ray, i'm inclined to say, No it isn't! Bear with me. There has never ever been a scientific flat earth theory. The ancients were well aware that the earth was spherical; you could see its shadow on the moon during a lunar ecliplse, you could see southern stars rise as you sailed south... You will sometimes read that Columbus was amazed to have sailed around the world. Pure historical nonsense. He wasn't. (I'm sure one could find Flat Earthers banging on in pseudo-scientific terms but peer review is a part of science and slings 'em out!)

But of course, yes, there are theories that have lived and died. But historians of science often argue that what happens more often is that theories are 'generalized' rather than scrapped and replaced by all-new ones. Newton was right in 'local circumstances'. (No high speeds, no huge masses.) It never worked for 'the anomolous perihelion of Mercury' which was the one planet in a Newton-busting gravitational field (being so close to the Sun's extreme mass.) Einstein generalized the theory to include any mass and any speed.

Nor do real scientists claim that their theories are 'fact.' The media try to present them as if they did so but if you read the big hitters of science in their own words they do not talk in these terms at all. They talk in terms of models, of our 'best theories'. This is increasingly the case, by the way. Certainty is dead. It was probably quantum theory that killed it once and for all.

If you look at the history of Darwinism it has (interestingly!) evolved but it has certainly not been scrapped. It has been refined.

So, in a nutshell, history is not as full of scrapped theories as you might think. Yes, they are there but so are generalizations and refinements. And no, the great scientists do not claim to deal in facts. Leave that to politicains and ... no, I'd better not mention religious leaders!!

Science is so important in our lives that I for one do my best to understand it, though my background is not in science at all.

Olly

Thanks for the comprehensive explanation Olly, It makes sense.

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Hello Everyone :(

I haven't been on StargazersL for quite a while, so it's good to catch up on a topic like this one.

What theory do I go for? Well, I'm mostly familiar with the ones I've I've been taught so far: Newtonian & Relativity (I'm teaching myself the latter as it's not taught at college yet) which both seem to work pretty well, in many cases. But I've been dwelling into 'multiverses' and 'string' theories too (read: Brian Greene, Michio Kaku et all)

I'm learning what's around and going for it, but I'm open to new ideas and discoveries :( It's a big world out there :(

Unless you're a mathematician - in which case you understand multidimensional space-time perfectly well. Your mental health is already wrecked, so why worry.

Yep! Why worry indeed ;)

String theorists are the worst;

String theorist: If you visualise this is in 15-dimensional space it is obvious.

Normal person: How do you 'visualise 15-dimensional space'!?!

String theorist: Well I just visualise an N-dimensional space and let N tend to 15...

(true story apparently)

:):D that's funny

Edited by Rosanella
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Ok,

If Newton & einstein are allowed to have theories, then so am I.

Like the string theory, I do believe that there is the possibility that other universe's exist.

I was on a science course some 40 years ago, just around the time of the discovery of quarks. (sub atomic particals that make up the core an atom). At the time, it seemed that atoms and electrons behaved in a similar manner to solar systems.

My theory is that there may be tiny universe's on a sub atomic level, and in the same way, we ourselves may be sub atomic to a larger universe that we can't see.

Aparently, there are vast distances between the core of an atom and the orbiting electrons, (similar to our solar system perhaps?). I have no equasions to back this theory up, so maybe it's not really a theory, just a crazy idea?

History is abundant with people who have had crazy idea's.

Edited by totalamateur
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....

My theory is that there may be tiny universe's on a sub atomic level, and in the same way, we ourselves may be sub atomic to a larger universe that we can't see.

...

History is abundant with people who have had crazy idea's.

I'm often tempted to think of human beings as 'particles' comparing to the vastness of the visible universe (we're tiny even seen compared to our galaxy). But we're 'developed particles', or rather 'evolved particles' with a well defined infrastructure (DNA) that governs the behaviour of cells and tissues in different parts of our body.

A micro-universe, perhaps amidst others, that has evolved throughout millennia and is still in phase of further evolution.

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