/sci/ - Science & Math

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Anonymous Mon Apr 21 15:55:40 2014 No.6492711 [DELETED]

[Reply] [Original]

OK /sci/, I'm no physicist or metaphysicist or anything, but I saw pic related and it seems like a really interesting expansion on the Anthropic Principle, if only I understood what it meant. Bear in mind it could be total bullshit TM, and I get the feeling that's what you're going to say.

>What does it mean to have more than 1 time dimension?
>Why is it unstable to have 2 or 4+ spatial dimensions with one dimension of time?
>Are the spatial and temporal axes merely inversions of one another?

Thanks.

>>	Anonymous Mon Apr 21 17:07:27 2014 No.6492818 Gonna have to bump this.

>>	Anonymous Mon Apr 21 17:31:21 2014 No.6492860 What would it mean to have n = 0 or n > 1 time dimensions?

>>	Anonymous Mon Apr 21 17:31:32 2014 No.6492861 I'd like to know this as well.

Anonymous Mon Apr 21 17:31:49 2014 No.6492862

That's from an old Tegmark paper IIRC.

OK, most basic explanation: Time and the three space dimensions are first of all four variables in the differential equations we use to express the laws of physics. The symmetries of nature as we understand them demand that these equations have a certain form (and they demand different things for time and space coordinates). Adding more space- or timelike coordinates isn't terribly hard, it's even straightforward. What two time dimensions are supposed to "mean" is everyody's guess - from a physical standpoint they mean that the equations look in a certain way and not another, and that's it.

So what you get is then a differential equation in more variables. These equations, or their solutions, then have "unfavorable" mathematical properties. That's where my knowledge ends.

Anonymous Mon Apr 21 17:33:48 2014 No.6492865

>>6492711
If the nature of the universe (number of dimensions) were so fundamentally different, maybe things like the gravitational constant would also be different. We assume that things would be "unstable" but that's according to what we're used to. What's to stop a different kind of matter from coalescing under different universal conditions?

>>	Anonymous Mon Apr 21 17:36:50 2014 No.6492868 File: 160 KB, 297x228, 1391815207755.png [View same] [iqdb] [saucenao] [google] >>6492860 OP here, that's one of my questions

Anonymous Mon Apr 21 17:39:35 2014 No.6492874

>>6492862
OK I kind of follow you. Could you go further? What do these equations describe?

And what kind of unfavorable properties are those? Seems like if we had one extra or one less spatial dimension, it wouldn't be so mathematically terrible. I have no idea about the temporal dimensions though.

>>6492865
Agreed, but maybe the pic overarches any orderly system for all I know.

Anonymous Mon Apr 21 17:45:37 2014 No.6492887

>>6492865

The problems run deeper, mathematically than "How large is my gravitational" constant. But the author still assumes basic symmetries to hold. If they don't, all bets are off I guess.

To be fair however, these symmetries are the foundations of how we perceive spacetime. If they don't hold the world would be so fundamentally different you could as well say you have four mumbo and two jumbo dimensions.

>>	Anonymous Mon Apr 21 17:47:51 2014 No.6492893 >>6492860 http://en.wikipedia.org/wiki/Fractal_dimension

>>	Anonymous Mon Apr 21 17:48:32 2014 No.6492894 >>6492862 Can I get a link to where I could read this paper? I doubt I'd get much from it but I'd still be interested.

Anonymous Mon Apr 21 17:54:36 2014 No.6492900

>>6492874
> What do these equations describe?
Everything we know.

These rules are rules *all* fundamental equations we know obey. That's the point. Classical electromagnetism, gravity in general relativity, quantum electrodynamic, quantum chromodynamics.

> it wouldn't be so mathematically terrible
Apparently, one less or extra spatial dimension *is* a problem. But you should show that pic to a mathematician to get more info on that.

>>	Anonymous Mon Apr 21 17:56:55 2014 No.6492903 >>6492894 I'm searching, give me a minute ..

Anonymous Mon Apr 21 17:57:06 2014 No.6492904
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>>6492900
>Everything we know.
>These rules are rules *all* fundamental equations we know obey. That's the point. Classical electromagnetism, gravity in general relativity, quantum electrodynamic, quantum chromodynamics.
oh god

so are there a lot of them or is it one big equation? What is the official name of these/this equation?

>>	Anonymous Mon Apr 21 17:59:10 2014 No.6492908 >>6492903 >>6492894 Found it. http://arxiv.org/abs/gr-qc/9704009

>>	Anonymous Mon Apr 21 17:59:47 2014 No.6492910 >>6492908 Many thanks

Anonymous Mon Apr 21 18:03:15 2014 No.6492921

>>6492860
Having 0 time dimensions simply means nothing happens, no events, everything is static for ever.

Having more than one time dimension makes no sense because what we measure as time is simply the difference between two events, and that can only have one dimension.

Anonymous Mon Apr 21 18:04:56 2014 No.6492922

>>6492904
>so are there a lot of them or is it one big equation? What is the official name of these/this equation?
Ok, here we go.

Let's start with the Standard Model.
So the QFT (quantum field theory) framework of the Standard Model means that we have to specify something called a Lagrangian density.
This Lagrangian density tells us how the various quantum fields of the Standard Model evolve with time.
And since all particles are (conjectured to be) excitations of these quantum fields, the Lagrangian density tells us how these particles interact.
So there are terms for the Electromagnetic force, terms for the Strong nuclear force, and terms for the weak nuclear force.

Gravity is described differently right now. First of all, no one has completely figured out how to make a quantum theory of gravity, so it is still described "classically." General relativity is the most modern and accurate description of gravity.

These are the 4 fundamental forces of physics; all other forces are forms of these.

>>	Anonymous Mon Apr 21 18:05:15 2014 No.6492923 >>6492904 http://en.wikipedia.org/wiki/Lorentz_covariance

>>	Anonymous Mon Apr 21 18:20:16 2014 No.6492941 >>6492908 Started trying to read that paper... and then I broke. This is why I don't too physics.

>>	Anonymous Mon Apr 21 20:21:00 2014 No.6493138 >>6492904 >what equation There's a lot of equations of equations that depend on time/spatial dimensions. Stupid example: s = si + vit + (at^2)/2

>>	Anonymous Mon Apr 21 20:24:14 2014 No.6493145 >>6493138 Yeah but >the differential equations we use to express the laws of physics.

>>	Anonymous Tue Apr 22 16:06:39 2014 No.6494477 bnump

>>	Anonymous Tue Apr 22 16:16:21 2014 No.6494497 >>6494477 why?

>>	Anonymous Tue Apr 22 18:10:01 2014 No.6494657 Can anyone who understands this explain what is meant by "too simple"?

>>	Anonymous Tue Apr 22 18:12:44 2014 No.6494660 The universe, what a concept!

>>	Anonymous Tue Apr 22 18:38:32 2014 No.6494738 >>6494660 this may be my favorite quote/line

>>	Anonymous Tue Apr 22 23:45:51 2014 No.6495303 >>6494657 I'm still reading it, but I believe he means that it's too simple to allow self aware structures.

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