# Is the universe expanding...or it is circuiting?

by Neghentropia
Tags: circuiting, expandingor, universe
 P: 18 ok, here it goes: this afternoon, wandering on wikipedia I stumbled accross a 3D projection of a rotating tesseract I spent some time looking at it, then i started thinking about the universe. a bit of context: I've always been passionate for astronomy. I like to read about other planets and stars, and I find amusing to know facts about extraterrestrial worlds. I don't really have a working knowledge of physics. I'm a biotechnologist and even though I spent two years studying engineering (well, studying...) I know little about the law of physics. So forgive me if what I'm going to say is either totally insane, common knowledge that any physycist already takes for granted, or not expressed in fluent English, which is not my first language... there are 3 things I don't "like" about what our universe. - the fact it's expanding (especially I don't like that it seems to be destined to expand indefinitely...mh...) - time as we intend it (i.e. non a touchable dimension) - the fact planets, stars, galaxies and everything out there revolve. why is everything moving in circle??? now, I know time is considered as a 4th dimensions. it bends, it crunches, it dilates, and I even read somewhere it actually IS a proper dimension, only that we perceive it as time (in this context proper dimension stands for dimension of space) that's why I was fascinated by the rotating tesseract. because it looks like how I would like our universe to be! a rotating 4D tesseract. looking better at the 3D projection I thought that if this was true, for 3D observers as we are a 4D rotating tesseract would appear to be expanding on one side an cruncing on the other (or better...it would appear to expand on half of its sideS and cruch on the other half). also, any circular motion in our apparent 3D universe would be the "translation" of a straight motion in the "proper" 4D universe. what I'm trying to say is that I could envision a universe, shaped a bit like a 3D thorus with a ridiculosly small center (the Big Bang) from which the whole univere texture spun out and to which it also crunch in. everything in a straight motion "upon itself" with the time playing the role of a dimension, which starts and finishes at the center of the universe. in this model (let's call it circuiting universe ) the Big Bang is a continuous event which takes place in that region of the universe where all the matter, after one complete circle, fell down again, crunching in infinitesimally small proportion before being ejected from the other side, ready for another circle, which leght is what we would call "age". ok, this is by far the biggest amount of nonsens I ever said while sober, but I hope you could enlighten me on the flaws of this idea. again. no, or very little, scientfic knowledge stands behind this topic so forgive me if this doens't comply with the forum's policy. cheers :)
Mentor
P: 12,113
 - time as we intend it (i.e. non a touchable dimension)
Try to define "touchable" without using "time" and "space" as different things in the definition ;).
 - the fact planets, stars, galaxies and everything out there revolve. why is everything moving in circle???
In general, every object has some angular momentum, and processes to get rid of that are are. Most objects have to rotate due to angular momentum conservation.
 now, I know time is considered as a 4th dimensions. it bends, it crunches, it dilates, and I even read somewhere it actually IS a proper dimension, only that we perceive it as time (in this context proper dimension stands for dimension of space)
Well, it is different, it has an opposite sign in the metric of spacetime. Very similar in some aspects, but not the same.
 because it looks like how I would like our universe to be!
 also, any circular motion in our apparent 3D universe would be the "translation" of a straight motion in the "proper" 4D universe.
A straight motion in 4D cannot give a rotation in 3D.

Using one spatial dimension to display time is very common in physics, and you can describe the universe as a static 4-dimensional object. That is fine.

But you won't get our universe as a result of a "moving" 4-dimensional object (that would require a 5th dimension for time, by the way).
 P: 126 "Why is everything moving in a circle." All planets and stars form from the collapse of interstellar clouds of dust (nebulas) which have a certain angular momentum. Planetary systems spin due to the angular momentum of their parent-nebula. (Law of the Conservation of Angular Momentum.) There are a few theories regarding the expanding universe. One states that that the universe will accelerate indefinitely and the rate of acceleration will increase as time goes by. Dark matter is the energy that is believed to cause the accelerated expansion. Another states that gravity will eventually slow down the acceleration and the universe will then collapse in on itself. (The Big Crunch.) String theory states that there is no one universe, rather, there is a multiverse. Universes can be formed when a larger universe splits. Likewise, a larger universe can be formed when two smaller universe merge. References you might find interesting: String Theory: http://www.youtube.com/watch?v=kYAdwS5MFjQ Why planets rotate: http://curious.astro.cornell.edu/que...php?number=416
P: 18
Is the universe expanding...or it is circuiting?

 Quote by mfb The universe does not care about your will ;).
dammit...

ok, I got the reason why everything rotates. basically just because if it didn't it wouldn't be like it is (something that reminds me of the anthropological principle...)

mfb, could you clarify why it's OK to consider time as a dimension for a static snapshopt of our universe, but I would need to add a 5th dimension to consider motion?

or is it because the motion itself? I mean, is time a "different" dimension than the other three so to allow the motion of a 3D object?

thanks for the video Absolute0, I did enjoyed it.
I have heard about string theory before and I have to admit the idea of a multiverse is quite tantalizing.
Mentor
P: 12,113
 mfb, could you clarify why it's OK to consider time as a dimension for a static snapshopt of our universe, but I would need to add a 5th dimension to consider motion?
If you want motion (a time-dimension) in a 4-dimensional "space"-space, you get a 5-dimensional spacetime.

 I mean, is time a "different" dimension than the other three so to allow the motion of a 3D object?
Time is a bit different, right.
P: 18
 Quote by mfb If you want motion (a time-dimension) in a 4-dimensional "space"-space, you get a 5-dimensional spacetime. Time is a bit different, right.
do you know where I could read more about the difference between space and time?
 Mentor P: 12,113 You can search for websites/books/scrips about special relativity - there are hundreds of them, some are good some are not.
 P: 2 I believe its not expanding -but that its contracting, and ever faster - the same laws and effecvts apply to points that are moving away from each other as to points that are moving towards each other accelerating - as a Point closer towards the centre accelerates away from a point further away and the point further away actually accelerates from a point even further away so red shift also applies - also it makes sense that we are in an imploding mode unlike an ever expanding universe, with matter accelerating ever greater towards the speed of light and in the process the eis being transformed into mass increase which may give answer to the dark matter problem as matter is being created/increased the closer it is accelerated towards the point of conjunction - also it may be that from this point energy/gamma rays or other are then shot out like from a mega black hole thus creating a rotating system of energy to mass transformation and dispersal to the outer limits where it is then formed back into particles/matter and collapses inwardly through gravitational attraction -this would make sense unlike all this ever expanding accelerating universe theory
 P: 18 I think that your model clashes with the evidence that universe is expanding in every direction it it was actually crushsing down, I imagine we would see it accelerating but we would also see evidence of shrinking somewhere out there unless the site of the Big-Cruch to be is out of the observable universe but still...if the universe is "falling" down towards a signle point we should be able to detect a gradient of acceleration toward such a point
Mentor
P: 12,113
 this would make sense unlike all this ever expanding accelerating universe theory
No it would not.
You don't get the same observations in every direction with that model (in particular, you would get directions with blueshift), the redshift/distance relation would be different everywhere, you don't get the cosmic microwave background, the correct isotopic composition of the world or anything else.

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