is this endlessness?

[Eddi]

I have a question that's been bugging me for years

I don't know how to explain this, it's simple to understand but hard to put in words.....

Imagine a chess board

Imagine you move a piece all the way to the edge of the opposite side, so that it is right at the top of the board

Now imagine you move it forward one space

And it reappears on the opposite edge of the board, right on the bottom of the board, to where it begun at the end of the game, on the same line

Now, imagine you have another piece and you move it to a square that is on the right edge of the board

You then move it one space to the right and it reappears on the left edge of the board, on the same row as it was before you last moved it

As though it has gone all around to the other side and as though the board is in some bizarre way round

What do you call this?

If the chess board works like that, does that mean that it is in effect never ending, as it is circular and has no edges?

Is that a type of infinity, or is it finite? It is at least endless and circular?

Might the universe work like that?

 

[RestlessSoul]

I'm not aware that a chess board works like that, but stars, planets and galaxies apparently do; in a sense we can say that time, in the manner in which we record it's passing, is cyclical rather than linear. Which brings to mind a couple of quotes;

The sun also rises, and the sun goeth down, and hastens to the place where he arose.
- Ecclesiastes 1:5

You run and you run to catch up with the sun, but it's sinking,
Rushing around, to come up behind you again.
- Pink Floyd, Time (from Dark Side of the Moon)

 

[ChristineM]

I have a question that's been bugging me for years

I don't know how to explain this, it's simple to understand but hard to put in words.....

Imagine a chess board

Imagine you move a piece all the way to the edge of the opposite side, so that it is right at the top of the board

Now imagine you move it forward one space

And it reappears on the opposite edge of the board, right on the bottom of the board, to where it begun at the end of the game, on the same line

Now, imagine you have another piece and you move it to a square that is on the right edge of the board

You then move it one space to the right and it reappears on the left edge of the board, on the same row as it was before you last moved it

As though it has gone all around to the other side and as though the board is in some bizarre way round

What do you call this?

If the chess board works like that, does that mean that it is in effect never ending, as it is circular and has no edges?

Is that a type of infinity, or is it finite? It is at least endless and circular?

Might the universe work like that?

Not a type of infinity just a circle.

The universe has been measured to be flat to 6 decimal places. A flat universe means it is infinite to within the accuracy of measurement

 

[Eddi]

The universe has been measured to be flat to 6 decimal places. A flat universe means it is infinite to within the accuracy of measurement

I don't understand any of that and I don't understand those pictures either

Physics is not my strong suit

I have a physicist friend and when he tells me about it I don't know what he's on about

But if a chess board was like as I described it you could say it was circular?

 

[Eddi]

A flat universe means it is infinite to within the accuracy of measurement

How is the universe flat?

Wouldn't that mean it was only two-dimensional?

 

[ChristineM]

I don't understand any of that and I don't understand those pictures either

Physics is not my strong suit

I have a physicist friend and when he tells me about it I don't know what he's on about

But if a chess board was like as I described it you could say it was circular?

It's easy, draw a triangle on a ball, measure the angles, they add up to more than 180 degrees. Draw a triangle on a curve the angles will total +/- 180 degrees but not 180 degrees.
Draw a triangle on a flat surface the angles will be 180 degrees.

Now take 2 points on the cmb which surrounds us, i.e. 360 degrees so you know the angles between each point and earth. Just measure the angle between the 2 points, you get 180.000000 degrees. Indicating a flat universe and thus (at least potentially) infinite


See the ball, fit the chessboard to it...

 

[ChristineM]

How is the universe flat?

Wouldn't that mean it was only two-dimensional?

No, it means its flat in all directions.

 

[Eddi]

It's easy, draw a triangle on a ball, measure the angles, they add up to more than 180 degrees. Draw a triangle on a curve the angles will total +/- 180 degrees but not 180 degrees.
Draw a triangle on a flat surface the angles will be 180 degrees.

Now take 2 points on the cmb which surrounds us, i.e. 360 degrees so you know the angles between each point and earth. Just measure the angle between the 2 points, you get 180.000000 degrees. Indicating a flat universe and thus (at least potentially) infinite


See the ball, fit the chessboard to it...

You mean screw the chessboard up so that it becomes a sphere?

 

[Eddi]

No, it means its flat in all directions.

So if I can go up and down, backwards and forwards, and left and right when I'm in the universe how is it flat?

 

[RestlessSoul]

How is the universe flat?

Wouldn't that mean it was only two-dimensional?

It's not literally flat, as in two dimensional. It's flat in that it obeys Euclidean geometry, so that parallel lines, right angles etc operate in space as they do on paper, up to astronomical scales.

 

[Eddi]

It's not literally flat, as in two dimensional. It's flat in that it obeys Euclidean geometry, so that parallel lines, right angles etc operate in space as they do on paper, up to astronomical scales.

So it's flat because an angle that is drawn on a piece of paper as being 2D works the same in 3D reality as it does on paper?

 

[The Hammer]

So if I can go up and down, backwards and forwards, and left and right when I'm in the universe how is it flat?

Good question

 

[The Hammer]

So it's flat because an angle that is drawn on a piece of paper as being 2D works the same in 3D reality as it does on paper?

Only in space I think.

 

[Eddi]

Only in space I think.

I have no idea

 

[ChristineM]

So if I can go up and down, backwards and forwards, and left and right when I'm in the universe how is it flat?

Take an infinite number of points on the cmb, draw lines between these points and a point on earth. No matter how many pairs of lines you investigate, the angle between a line between the any 2 points and the lines to the point on earth will add up to 180 degrees, up,down left, right.

 

[Eddi]

Take an infinite number of points on the cmb, draw lines between these points and a point on earth. No matter how many pairs of lines you investigate, the angle between a line between the any 2 points and the lines to the point on earth will add up to 180 degrees, up,down left, right.

I'm sorry but I don't understand

It doesn't compute!

I always thought the universe was in three spatial dimensions, is that actually false?

I don't understand how it can be both flat and in three dimensions

 

[RestlessSoul]

So it's flat because an angle that is drawn on a piece of paper as being 2D works the same in 3D reality as it does on paper?

Yeah, sort of. As @ChristineM has shown above, a triangle described between three point in space, will have angles totalling 180 degrees, unlike a triangle drawn on the surface of a sphere.

And it's to do with the critical density of the universe; in a more dense universe, gravity would pull everything into the shape of a ball. In a lower density universe, gravity would be unable to slow the expansion, causing time and space to distort into something resembling the saddle shape in #3 above.

The important thing to bear in mind is that there is a difference between the geometry of the universe, and it's dimensions.

 

[Eddi]

Yeah, as @ChristineM has shown above, a triangle in space will have angles totalling 180 degrees, unlike a triangle drawn on the surface of a sphere.

And it's to do with the critical density of the universe; in a more dense universe, gravity would pull everything into the shape of a ball. In a lower density universe, gravity would be unable to slow the expansion, causing time and space to distort into something resembling the saddle shape in #3 above

I don't understand the difference to a triangle that exists in space and a triangle that's only drawn a piece of paper

 

[ChristineM]

I'm sorry but I don't understand

It doesn't compute!

I always thought the universe was in three spatial dimensions, is that actually false?

I don't understand how it can be both flat and in three dimensions

Take a ruler. Point it into space. Point it to another place in space. The plane between the two imaginary lines is flat.

You can.do that in any direction. The plane between any 2 lines is flat.

 

[sun rise]

It is at least endless and circular?

According to an Eastern conception, yes.