Is the Universe two dimensional?

[woolyhead]

A female (as it happens) PhD physicist on Physics Forum told me that the universe is two dimensional. I don't know about you but I reckon that's rubbish. Her reasoning was that because parallel lines don't cross over (how does she know?) that proves her point. I must be wrong about this but for my money the universe, the earth and a marble are all three dimensional bodies. How about you?

[Jim Hardie]

She's right about parallel lines because that's how they are defined but talking ******** about everything else.

[Guest sibon]

Nice critique of string theory there Jim

 

The holographic principle suggests that the Universe could be viewed as 2 dimensional. But I'm pretty sure that I'm 3D, personally.

[Waldo]

What does the universe exist in? What context? I can look at a sheet of A4, and say there are 2 (or 3) dimensions to it; but, that sheet of A4 exists within a context, something larger than it, a reference from which we can contrast and measure a number of dimensions.

 

Not so much with the universe itself.

[Guest sibon]

What does the universe exist in? What context? I can look at a sheet of A4, and say there are 2 (or 3) dimensions to it; but, that sheet of A4 exists within a context, something larger than it, a reference from which we can contrast and measure a number of dimensions.

 

Not so much with the universe itself.

 

Try rolling the sheet of paper up and looking at the inner surface. Report back on the number of dimensions when you are ready:)

[I1L2T3]

A female (as it happens) PhD physicist on Physics Forum told me that the universe is two dimensional. I don't know about you but I reckon that's rubbish. Her reasoning was that because parallel lines don't cross over (how does she know?) that proves her point. I must be wrong about this but for my money the universe, the earth and a marble are all three dimensional bodies. How about you?

 

Just get some 3D spectacles from the cinema and wear them all the time. Problem solved.

[Waldo]

Try rolling the sheet of paper up and looking at the inner surface. Report back on the number of dimensions when you are ready:)

 

Sure; but even that still exists within a context. I can look at it from outside and compare and contrast it with it's surroundings.

 

Try doing that with the universe itself.

[melthebell]

Nice critique of string theory there Jim

 

The holographic principle suggests that the Universe could be viewed as 2 dimensional. But I'm pretty sure that I'm 3D, personally.

do people need to wear those silly glasses when talking to you then?

[TimmyR]

I'm not entirely convinced that the universe exists.

[woolyhead]

Sibon, the inner surface of the rolled up sheet of paper is two dimensional but that's only one part of the rolled up sheet of paper. It also has diameter when viewed for outside, making it 3 dimensional, doesn't it? Starting on the surface of the paper any measurement of the diameter would require a wormhole, maybe. So is a wormhole part of the universe or not? I reckon a similar thing to measuring diameter is to measure curvature. What about that? I mean that even the people living on this so called flat surface could imagine it being curved upward say, and measure the curvature. From the result they would realise that their universe was indeed 3 dimensional, wouldn't they?

 

---------- Post added 02-07-2017 at 13:26 ----------

 

I'm not entirely convinced that the universe exists.

 

For you it doesn't

 

---------- Post added 04-07-2017 at 09:46 ----------

 

Sure; but even that still exists within a context. I can look at it from outside and compare and contrast it with it's surroundings.

 

Try doing that with the universe itself.

When we imagine the universe we are looking at it from the outside, aren't we? Aren't our minds outside the universe? I can imagine a universe that's inside ours, can't you? Of course this is a conundrum. My head is obviously inside the universe but it's a model of the universe that's inside my head. I only think the universe is inside my head. It isn't really. So what is this "really"? What is reality? Everything I think of as being real is just a model inside my head. And another thing: how would you measure the curvature of the universe?

Edited July 16, 2017 by woolyhead