4-d

[why06]

<font color="yellow">What are the four dimensions?<font color="white"><br /><br />I have a little cousin and he does not believe me - that there are three spatial dimensions in our universe and another dimension of time ( the for the phrase space-time)<br /><br />Still though it would be helpful to learn other members take on this I also understand that there have been vaqgue concepts in the string theory and others concerning otherdimensions. beyond 4-d .<br /><br />last but not whatexactly is a dimension?</font></font> <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>

 

[doubletruncation]

I think the dimension of a space is basically the number of independent variables you need to be able to describe the position of an object. If you want to specify the position of something along a line you only need one independent coordinate so it's one dimensional, for a plane or even the surface of a sphere you only need two coordinates so those are two dimensional surfaces etc. I think you're right in saying that we live in 4 dimensions (or more, depending on string theory etc.) because we know that it takes at least 3 spatial numbers and 1 temporal number to specify any point in this space (there are some holographic theories in which one of the coordinates is basically a function of the others so that we only live in a 3 dimensional universe - but lets just ignore that). In relativity the space and time coordinates get mixed up in transforming from one observer to another, so it's really quite clear that it's a four dimensional space rather than a separate 3 dimensional and 1 dimensional spaces. That said, the temporal dimension is unique from the spatial dimensions in that all observers (except for massless particles) see time increasing. <div class="Discussion_UserSignature"> </div>

 

[why06]

thanks for the reply<br /> <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>

 

[vandivx]

if you will feed that still healthy mind what today's scientists believe, he won't be instrumental of advancing science when he grows up same as today's scientists aren't.<br /><br />Dimensions are not physical features of reality, they are just a way how we abstractly thinking humans parcel it out to get a handle on it. Sometimes it is convenient to work with just one or two dimensions, depends on the problem, sometimes we use all three spatial and one time dimension, other times we might use even more dimensions, like ten or whatever floats your boat. However many dimensions scientists work with, it is just abstract thing and the physical reality out there doesn't get affected by it. Personally I don't buy that view that there are somehow more dimensions to reality than what we see because that view treats dimensions as something physically real. It is one thing to make calculations with n-dimensions and quite another claiming that they physically somehow exist out there, that reality that we see is therefore only some small part of what's out there, with the rest being hidden in those additional dimensions. <br /><br /><br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[dragon04]

If you want to blow your cousin's mind, lay 11-dimensional space-time on him. 10 physical dimensions plus time.<br /><br /><br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[observer7]

For an interesting discussion on dimensions and their importance / relavence in physics read Chapter 10 of "The Constants of Nature" by John Barrow.<br /><br />He has a great graphic that shows what happens when the number of space and time dimensions is varied. Basically, if atoms are to form then the universe has to have 3 space and 1 time dimension. Other configurations are unstable or too simple to support the creation of matter. The anthropic principle strikes again.<br /><br />--- <div class="Discussion_UserSignature"> <em><font size="2">"Time exists so that everything doesn't happen at once" </font></em><font size="2">Albert Einstein</font> </div>