michel123456 Posted April 16, 2011 Share Posted April 16, 2011 If you make a line starting at point zero and going to infinite, is it really representing something infinite? The question arises because the "infinite" line has a starting point: it has an edge. Can we say that something infinite can have an edge? I am confused. When something starts somewhere, in space or in time, it has a starting point (kind of tautology). Can we consider this starting point as an edge? Link to comment Share on other sites More sharing options...
insane_alien Posted April 16, 2011 Share Posted April 16, 2011 yes, of course you can. as long as it only has one end in your case. Link to comment Share on other sites More sharing options...
michel123456 Posted April 16, 2011 Author Share Posted April 16, 2011 yes, of course you can. as long as it only has one end in your case. Hm. Following that logic the Big Bang is the edge of spacetime. Link to comment Share on other sites More sharing options...
jackson33 Posted April 16, 2011 Share Posted April 16, 2011 If you make a line starting at point zero and going to infinite, is it really representing something infinite? The question arises because the "infinite" line has a starting point: it has an edge. Can we say that something infinite can have an edge? I am confused. When something starts somewhere, in space or in time, it has a starting point (kind of tautology). Can we consider this starting point as an edge? [/Quote] Michel; That's a play on words, since nothing can begin infinite, simply must be and finite would apply define the line, space or time, to a time line. You can't make (define) something finite, infinite "the line". For instance in Astronomy, if the Universe began, it's to a finite place, but if it had always existed in some manner, it could well be infinite. Space, however could be either... My two cents... Link to comment Share on other sites More sharing options...
Spyman Posted April 16, 2011 Share Posted April 16, 2011 If you make a line starting at point zero and going to infinite, is it really representing something infinite? The question arises because the "infinite" line has a starting point: it has an edge. Can we say that something infinite can have an edge? I am confused. When something starts somewhere, in space or in time, it has a starting point (kind of tautology). Can we consider this starting point as an edge? I used the example of pi in the other thread, it has a starting point, (the digit 3), and then continues to have infinite decimals. So it has an edge and is still infinite in length. Hm. Following that logic the Big Bang is the edge of spacetime. We don't know if the Big Bang is the edge of spacetime, it is currently our theoretically edge of observation but not necessarily a true edge. Link to comment Share on other sites More sharing options...
Shadow Posted April 16, 2011 Share Posted April 16, 2011 yes, of course you can. as long as it only has one end in your case. Actually, that's not entirely true; you can represent infinity "with two ends". Just draw any line, as short or as long as you wish, and "count" the number of points it's made of. Or, I can say this a little differently; count the real numbers between a number and that same number enlarged by any positive amount, mathematically [math]| \langle x;\hspace{1 pt} x+y \rangle |, \hspace{1 pt} x \in \mathbb{R}, \hspace{1 pt} y \in \mathbb{R}^+[/math]. Link to comment Share on other sites More sharing options...
DrRocket Posted April 16, 2011 Share Posted April 16, 2011 Hm. Following that logic the Big Bang is the edge of spacetime. No more so than the North Pole is the edge of the Eaarth. Link to comment Share on other sites More sharing options...
michel123456 Posted April 16, 2011 Author Share Posted April 16, 2011 (edited) I used the example of pi in the other thread, it has a starting point, (the digit 3), and then continues to have infinite decimals. So it has an edge and is still infinite in length. Yes, it is the source of my question. Say that we are inhabitants of the Pi world, on the tenth digit. Looking at right, we see infinite, looking at left we look at the edge only 10 digits away. That makes our pi world totally asymetric. There is a beginning, there is no end. And there is a kind of flow coming from the beginning and going to infinite, even if Pi is a static geometric number (I mean Pi is not growing). No more so than the North Pole is the edge of the Eaarth. That is bad analogy IMHO. Edited April 16, 2011 by michel123456 Link to comment Share on other sites More sharing options...
Spyman Posted April 18, 2011 Share Posted April 18, 2011 If pi would represent space in an analogy then we are from our point of view on the first digit (3) and looking outward we can currently only see ~46 billion digits in a circular sphere around us. That makes the world symmetric around us and doesn't tell whether there really is an asymetry or if there is any edge at all further out. If pi represents time then we are not able to view any further into the future and determine if there is any end of time. According to cosmological time keeping we are on the ~14 billionth digit since when looking back in time we can not see further than what we perceive to be the first digit (3), but we don't know what or if there was a before. I don't think I understand your question, clearly pi exists, has an edge and an infinite row of digits but there is no reason that the world must be like pi. The Universe could be finite without any edges or infinite in extent and if the world somehow turns out to be like pi then we would have to accept that the world is totally asymetric. Link to comment Share on other sites More sharing options...
michel123456 Posted April 18, 2011 Author Share Posted April 18, 2011 Isn't it? Link to comment Share on other sites More sharing options...
Spyman Posted April 19, 2011 Share Posted April 19, 2011 Huh, didn't you read my post? If you don't want to discuss then why opening a thread on the subject? Link to comment Share on other sites More sharing options...
DrRocket Posted April 19, 2011 Share Posted April 19, 2011 That is bad analogy IMHO. Actually, it is not. GR models spacetime as a Lorentzian manifold without boundary. Link to comment Share on other sites More sharing options...
michel123456 Posted April 19, 2011 Author Share Posted April 19, 2011 (edited) Huh, didn't you read my post? If you don't want to discuss then why opening a thread on the subject? I was answering to your post. You wrote : and if the world somehow turns out to be like pi then we would have to accept that the world is totally asymetric. and I answered: Isn't it? (asymetric). I think, following existing theories, it is fundamentaly asymetric. _time is asymetric (the arrow of time) _gravity is asymetric (gravitation is only attractive) _even space is (considering that negative distance do not exist) Edited April 19, 2011 by michel123456 Link to comment Share on other sites More sharing options...
Spyman Posted April 19, 2011 Share Posted April 19, 2011 Now I am even more confused about what you are asking... Link to comment Share on other sites More sharing options...
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