# Who said the fourth Dimension has to be time?

by Gacha
Tags: dimension, time
P: 784
 Quote by Gacha Looks like I answered it myself. In maths we could create up to 26 valid dimensions on paper
Why only 26?

 Quote by Gacha (a more specific example: in this Invariant for the heterotic superstring model - what does this vertically mirrored 'L' between L and $\mu$ mean/stand for?)
Generally it means Christoffel symbols: http://en.wikipedia.org/wiki/Christoffel_symbols
P: 8
 Quote by Vorde Sounds dubious at the very least to me, where did you hear this? The reason people throw around 10 dimension (or 10+1 dimension theories where the +1 is a time dimension) theories is, as I read from a book (albeit a popular science one), because the current research is that M-Theory might be 'workable' in 10+1 dimensions. But there are lots and lots of theories that say otherwise. Many stick with our familiar (thanks to Einstein et al) 3+1 dimensions, some have 10 dimensions, some 11 and some 28 and still others with many more. There is as of yet no evidence to suggest that the universe has any more than 3 dimensions of space and 1 dimension of time.
I just haven't heard of many other things yet so it might just be that I take things I recently caught up on for too granted. I should get rid of that gullibility as soon as possible.

 Quote by Vorde Why only 26? Generally it means Christoffel symbols: http://en.wikipedia.org/wiki/Christoffel_symbols
Just as above, the equation I saw was only valid for this many dimensions the way I understood it. Thus I have just taken it that way since I didn't know any better, so never mind :)

Thanks a lot for the hint, really helpful!
 P: 37 Okay, I did not read every posting here but there should be something clarified: There is a pretty big difference between the four dimensions of SRT (and GRT): You can call the four x_i, x_j, x_k and x_m, but I am not sure why in this thread it is not told that - let us say x_m is the time - the light sphere is (x_i)^2+(x_j)^2+(x_k)^2=(x_m)^2? You can reorder and call it whatever you want - but the "time dimension" is not the same a space dimension?! You should clearly point that out.
P: 148
 Quote by Gacha The tenth dimension is supposed to contain all possibilities for all possible timelines for all possible universes so ultimately there should be a cap as there is no more space in our imagination for another two points to create the next dimension.
Where did you hear this? This isn't even string theory. This is pseudoscience.

Whoever told you this nonsense is most likely not a physicist, is not educated, is making things up and is lying to you. It doesn't make sense for a dimension to contain anything. A dimension is a degree of freedom. Unlearn what this person had taught you.

You need to be more careful when learning physics. Don't just trust any information anyone gives you. Do your research to see if they actually are a physicist.
 P: 853 It actually doesn't matter who tells you what all it matters is are you being told the truth or lies easy as that. ofcourse it is easier to learn in sites like this one where there are people who sort out fake things but it's not like everyone needs a Phd to understand or be qualified to open his mouth. As long as the person is right it's ok.But just as every teacher also every student or self taught especially has the responsibility not only to demand and seek information but to also check the validity of it. Even professors can get things wrong or messed up we all are just humans you know. But believe me and I can assure you both Gacha and others the one who seeks always finds.It jst is like that. Now in the end of the day most of the time when one gets something wrong it's not because he would have been deliberately tough wrong rather it was his or hers choice to follow up some explanations that are not right. i know many crackpots who have actually some pretty good skills and thinking they just reject the reality because they like what they make up more than what someone else has validated and experimented. The things that we like an accept are the ones that make us who we are.
 Mentor P: 16,488 OK, I think that this thread has outlived its usefulness. The idea of time as the fourth-dimension comes from special relativity. It is incredibly well-validated experimentally: http://www.edu-observatory.org/physi...periments.html If you have follow-up questions about relativity, please post them to the relativity forum. The idea of more than 3 spatial dimensions is associated with string theory and its spinoffs. If you have follow-up questions about that, please post them to the beyond the standard model forum. Be sure and read the sticky before posting there. That forum is not for personal theories.

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