Just watching a bit of Stephen Hawking on telly and there's summat I can't get my head around. A huge mass such as a planet or moon will bend the space around it. I just can't understand that. Its as though space is a 2D thing. I could get it then.Otherwise space is,well, nothingness so how can you bend nothing? It will still be the shape of a nothing. If that makes sense. Can someone explain that?

It's a bit of a trick - instead of objects curving in orbits, they go straight in the curved space. Now gravity is made redundant, replaced with fairly horrible curved geometry. It works for physicists because it predicts correctly how massless particles (photons) react. For us it's easier just to pretend gravity DOES exist.....
You think you're just sat in that chair - no you're not, you're accelerating upwards in a curved universe....
Bob
PS that could all be horribly wrong - you shouldn't believe stuff you read on here....

Hmm. So as soon as an object stops moving in a curve style then it's put down to the fact that the space must be curved instead? Sounds a bit a weak argument that.
How can I get one of these jobs making up ideas?

[Edited on 3/3/08 by mistergrumpy]

Well I have kind off grown up with this stuff; since I was a kid I have read al the latest theories and the like. Forget about visualising curved space, even the scientists can’t do that, only understand its effects. I’m not to impressed Hawkins stuff I’ve read his books and he gives very little direct evidence for his theories and one has ever detected his exploding black holes either.

Space is not a nothing, it has been measured by satellites above the earth to slowly revolve around the planet dragged by earths own rotation. This shows something is there, black holes are suppose to do this at a much greater rate. Waves in gravity are also predicted and have been indirectly measured coming from neutron stars, another proof that there is a 'sub space' as trekies like to call it.

Why not get a book on it, I think you'll find it fascinating, just don't get hawking one as it's a bit boring and out of date.

[Edited on 3/3/08 by Mr Whippy]

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Originally posted by mistergrumpy
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How can I get one of these jobs making up ideas?

[Edited on 3/3/08 by mistergrumpy]

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Originally posted by mistergrumpy
Hmm. So as soon as an object stops moving in a curve style then it's put down to the fact that the space must be curved instead? Sounds a bit a weak argument that.
How can I get one of these jobs making up ideas?

[Edited on 3/3/08 by mistergrumpy]

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If photons have no mass, how does a Crookes Radiometer work?

Forget that, error in thinking self evident, but how does it work anyway?

[Edited on 3/3/08 by Confused but excited.]

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Originally posted by Confused but excited.
If photons have no mass, how does a Crookes Radiometer work?

Forget that, error in thinking self evident, but how does it work anyway?

[Edited on 3/3/08 by Confused but excited.]

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I think this image, used often in books gives the best representation of how curved space would look, similar to the common rubber sheet model but wrapped right round the object. It also shows a gravity wave radiating from a star or a supernova
Rescued attachment spacetimelu3.jpg

You know it's nice to see others are interested in this kind of thing, I have always been fascinated by it, even though my mum always said I was filling my head with rubbish

Now I seem to have to explain it all to her and my dad when they have watched a program on the telly

mistergrumpy will be sitting there thinking OMG what have I started

[Edited on 3/3/08 by Mr Whippy]

I watched that last night and I have to say I prefer the 'space bending' idea, I've never been able to get my head around gravity over long distances, ie how the sun can exert such a pull on say pluto when it's such a long way away ..... it's much easier to visualise it if you image the rubber sheet model instead.....

I love all this stuff, I just wish I had the brain capacity to understand it a little more.

All interesting. I'm with you Jasper and wished my head had a bit more space to absorb it all. Its kinda like maths. I really like it but can only get so involved before my head collapses
I think its that I seem to be interested a bit in everything and how it works and effects other things and the reason I haven't bought a book yet is that I have too many 'interests' going on. I just have a thirst for more. Jack of all, master of none and stuff.
I think my problem is in the definition of 'space'. To me, I was thinking of it as literally nothing. Its the electrons and protons and the light waves and magnetic/gravitational forces within it that are doing the work. I think I get it now.

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Originally posted by JasperI've never been able to get my head around gravity over long distances, ie how the sun can exert such a pull on say pluto when it's such a long way away

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The main thing to remember is that space has never been empty. It's full of stuff, just less stuff than we have inside our atmosphere. As said, a full 3D model of bent space is very hard to visualise, but the old rubber sheet model does well enough. There are many things that happen that people are still struggling to explain, so much so that they had to invent new forms of maths to try and explain them!!
Oh, and to really confuse you, are you aware that right now millions of tiny particles are thundering through your body whilst you read this?! You're not alone in being interested in such things, just that most get lost in the mind numbing vastness of it all.

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Originally posted by DIY Si

Oh, and to really confuse you, are you aware that right now millions of tiny particles are thundering through your body whilst you read this?!

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I read some books on this and got suitably fired up to go and study it at Uni. I thought i'd learn enough to be able to understand it, but actually i just leanrt enough to appreciate how little i really knew. :s

For me Einstein's greatest legacies are the philosophical leaps he made from 'established' models of space and time that had existed almost unchanged for a couple of thousand years. Linking space and time was a big conceptual jump, as was stating the constancy of the speed of light. For what my tiny little opinion's worth, i think that should be re-named the Speed of Time, as there is a maximum rate at which anything can travel and light will go at that speed if it gets the chance, but it doesn't mean that the limit is just whatever speed the light happens to be doing, as light can go much slower sometimes.

Damn, now my head hurts.