mistergrumpy
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| posted on 3/3/08 at 09:21 PM |
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Curved Space?
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?
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Bob C
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| posted on 3/3/08 at 10:09 PM |
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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....
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mistergrumpy
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| posted on 3/3/08 at 10:23 PM |
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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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Mr Whippy
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| posted on 3/3/08 at 10:33 PM |
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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]
Fame is when your old car is plastered all over the internet
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iank
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| posted on 3/3/08 at 10:34 PM |
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quote:
Originally posted by mistergrumpy
...
How can I get one of these jobs making up ideas?
[Edited on 3/3/08 by mistergrumpy]
Step 1 Maths degree
Step 2 Physics degree
Step 3. Maths PhD
Step 4. The right mushrooms in industrial quantities.
You think that's mad, try and understand the more advanced quantum physics.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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Mr Whippy
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| posted on 3/3/08 at 10:38 PM |
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quote:
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]
You would find that all objects will be going in a curve through space due to gravity from everything around, galaxies, other stars, any matter at
all. To go in a true straight line you would need to apply a constant force, like a rocket.
Tell you what is funny though, I've found a flaw in Dr. Mallett’s time machine, its a classic balls up, I was discussing it with friends and
he's doomed, what a pity  I loved the idea.
[Edited on 3/3/08 by Mr Whippy]
Fame is when your old car is plastered all over the internet
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Confused but excited.
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| posted on 3/3/08 at 10:47 PM |
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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.]
Tell them about the bent treacle edges!
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Mr Whippy
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| posted on 3/3/08 at 10:52 PM |
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quote:
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.]
Sorry its cos it not in vacuum, what ever side is heated causes a very slight density change in the air on the heated side, which amounts to a
pressure on the plate
Fame is when your old car is plastered all over the internet
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Mr Whippy
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| posted on 3/3/08 at 11:02 PM |
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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
Fame is when your old car is plastered all over the internet
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Mr Whippy
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| posted on 3/3/08 at 11:20 PM |
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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]
Fame is when your old car is plastered all over the internet
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Jasper
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| posted on 4/3/08 at 08:28 AM |
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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.
If you're not living life on the edge you're taking up too much room.
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mistergrumpy
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| posted on 4/3/08 at 07:43 PM |
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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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MikeRJ
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| posted on 7/3/08 at 11:07 AM |
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quote:
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
Because the sun is very, very, very big and heavy
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DIY Si
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| posted on 7/3/08 at 12:59 PM |
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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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Confused but excited.
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| posted on 7/3/08 at 02:29 PM |
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quote:
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?!
They have wonderful names like neutrinos, oh and pies and chips.
Tell them about the bent treacle edges!
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Rob Palin
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| posted on 7/3/08 at 03:08 PM |
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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.
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