100 years on: the picture that changed our view of the universe
https://www.theguardian.com/science/201 ... utlookmail
cant say I understand any of this stuff either Einsteins or Newstons : forces = action at a distance; Einsteins = space is curved - did Einstein just revamp the idea of the Ether and give it a twist? I really dont know what we mean by "space" any way since I thought it was just nothing, the gap between things especialy in a vacuum. How can nothing be curved?
100 years on: the picture that changed our view of the universe
Re: 100 years on: the picture that changed our view of the universe
I remember trying my hardest to plough through a GR textbook in my student days (it wasn't on the undergrad curriculum, I was doing it out of idle curiosity). Having got bogged down in covariant and contravariant tensors, metrics and Christoffel symbols, etc. etc., I decided it was too tough going for me!
Though I do recall one amusing remark from the book (1950s vintage). Commenting on the Schwartzschild solution for a spherically-symmetric field, it was stated that the formula gives a nonsensical result if a mass is compressed within a certain radius. But don't worry, this never applies, because no mass can ever be compressed into so small a radius....
Since then, we've got Black Holes....
Though I do recall one amusing remark from the book (1950s vintage). Commenting on the Schwartzschild solution for a spherically-symmetric field, it was stated that the formula gives a nonsensical result if a mass is compressed within a certain radius. But don't worry, this never applies, because no mass can ever be compressed into so small a radius....
Since then, we've got Black Holes....
Suppose that this room is a lift. The support breaks and down we go with ever-increasing velocity.
Let us pass the time by performing physical experiments...
--- Arthur Eddington (creator of the Eddington Number).
Let us pass the time by performing physical experiments...
--- Arthur Eddington (creator of the Eddington Number).
Re: 100 years on: the picture that changed our view of the universe
But vacuum is not nothingness. There's a lot going on in there - mainly photons (light) racing around in all directions. Eddington demonstrated that they are following a curved path through the vacuum - though, as the article points out, he may have fiddled the results. Later experiments have been more trustworthy.mercalia wrote:How can nothing be curved?
Suppose that this room is a lift. The support breaks and down we go with ever-increasing velocity.
Let us pass the time by performing physical experiments...
--- Arthur Eddington (creator of the Eddington Number).
Let us pass the time by performing physical experiments...
--- Arthur Eddington (creator of the Eddington Number).
Re: 100 years on: the picture that changed our view of the universe
I'm reminded of the Gell-Mann evasion. When a reporter asked him to explain the work that won him a Nobel in simple terms, he replied "if I could explain it in simple terms I wouldn't have won a Nobel".
My own thought is that a pure vacuum may exist in space but space, devoid of the known fields and particles, is still more than just a vacuum.
Just don't ask me what.
My own thought is that a pure vacuum may exist in space but space, devoid of the known fields and particles, is still more than just a vacuum.
Just don't ask me what.
Have we got time for another cuppa?
Re: 100 years on: the picture that changed our view of the universe
661-Pete wrote:But vacuum is not nothingness. There's a lot going on in there - mainly photons (light) racing around in all directions. Eddington demonstrated that they are following a curved path through the vacuum - though, as the article points out, he may have fiddled the results. Later experiments have been more trustworthy.mercalia wrote:How can nothing be curved?
well as I understand it masses curve space thats E's idea? A thought edperiment: suppose we have a universe with a genuine vaccum around a single mass ( no light etc) , space around it would still be curved ( though nothing to follow the curves ). How can nothing be curved? so E's space is really the ether that was dismissed?
Re: 100 years on: the picture that changed our view of the universe
It depends how you define the 'ether' (or 'aether'). What it is not, as Einstein proved (in his Special Theory), is a fixed medium stationary in the Universe, so that every object moves at a defined speed relative to it. In fact it was Michelson and Morley, who demonstrated that, before Einstein, in 1887.mercalia wrote:well as I understand it masses curve space thats E's idea? A thought edperiment: suppose we have a universe with a genuine vaccum around a single mass ( no light etc) , space around it would still be curved ( though nothing to follow the curves ). How can nothing be curved? so E's space is really the ether that was dismissed?
That doesn't mean that the aether doesn't exist, in some form or other. These are only models, after all.
As Audax points out, the vacuum is a very complex thing. Even if there were no light, it would still be, like a 'soup', packed full of virtual particles, which jump out of nothingness in an instant and almost immediately vanish again into that nothingness. Heisenberg's Uncertainty Principle predicts that this may happen without violating the Laws of Physics. And the conjectured Hawking Radiation, emitted by Black Holes, consists of survivors from this virtual particle soup.
Don't ask me to go into more detail. I've forgotten nearly all my Physics...
Suppose that this room is a lift. The support breaks and down we go with ever-increasing velocity.
Let us pass the time by performing physical experiments...
--- Arthur Eddington (creator of the Eddington Number).
Let us pass the time by performing physical experiments...
--- Arthur Eddington (creator of the Eddington Number).
Re: 100 years on: the picture that changed our view of the universe
661-Pete wrote:It depends how you define the 'ether' (or 'aether'). What it is not, as Einstein proved (in his Special Theory), is a fixed medium stationary in the Universe, so that every object moves at a defined speed relative to it. In fact it was Michelson and Morley, who demonstrated that, before Einstein, in 1887.mercalia wrote:well as I understand it masses curve space thats E's idea? A thought edperiment: suppose we have a universe with a genuine vaccum around a single mass ( no light etc) , space around it would still be curved ( though nothing to follow the curves ). How can nothing be curved? so E's space is really the ether that was dismissed?
That doesn't mean that the aether doesn't exist, in some form or other. These are only models, after all.
As Audax points out, the vacuum is a very complex thing. Even if there were no light, it would still be, like a 'soup', packed full of virtual particles, which jump out of nothingness in an instant and almost immediately vanish again into that nothingness. Heisenberg's Uncertainty Principle predicts that this may happen without violating the Laws of Physics. And the conjectured Hawking Radiation, emitted by Black Holes, consists of survivors from this virtual particle soup.
Don't ask me to go into more detail. I've forgotten nearly all my Physics...
but these virtual particles aint space are they? just pecuilar matter. if you are saying that it is these virtual particles and other kinds of weirdos that explain why space can get curved then Newton wasnt so wrong in that masses were distorting space because they were affecting these other particles, which explain why space seems to get curved, action at a distrance?